WO2016119212A1

WO2016119212A1 - Bearer selection for group service communication and service continuity

Info

Publication number: WO2016119212A1
Application number: PCT/CN2015/071944
Authority: WO
Inventors: Xipeng Zhu; Jun Wang; Xiaoxia Zhang
Original assignee: Qualcomm Incorporated
Priority date: 2015-01-30
Filing date: 2015-01-30
Publication date: 2016-08-04
Also published as: WO2016119634A1

Abstract

A method, an apparatus, and a computer program product for group service communication are provided. The apparatus determines a transmission type for sending a group call message of a group call service to a set of UEs based on information received from the set of UEs. The transmission type may be one of a unicast (UC) transmission type, a point-to-multipoint (PTM) transmission type, and a multimedia broadcast service (MBMS) transmission type. The apparatus establishes at least one of one of a UC bearer, a group bearer or a MBMS bearer for the set of UEs based on the determination, and sends the group call message through the at least one established bearer to the set of UEs.

Description

BEARER SELECTION FOR GROUP SERVICE COMMUNICATION AND SERVICE CONTINUITY

BACKGROUND Field

The present disclosure relates generally to communication systems, and more particularly, to transmission type determination and bearer establishment for group service communication, and service continuity of group service communications.

Background

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power) . Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE) . LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP) . LTE is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA on the downlink (DL) , SC-FDMA on the uplink (UL) , and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi- access technologies and the telecommunication standards that employ these technologies.

SUMMARY

In an aspect of the disclosure, a method, a computer program product, and an apparatus for group service communication are provided. The apparatus determines a transmission type for sending a group call message of a group call service to a set of UEs based on information received from the set of UEs. The transmission type may be one of a unicast (UC) transmission type, a point-to-multipoint (PTM) transmission type, and a multimedia broadcast service (MBMS) transmission type. The apparatus establishes at least one of one of a UC bearer, a group bearer or a MBMS bearer for the set of UEs based on the determination, and sends the group call message through the at least one established bearer to the set of UEs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a network architecture.

FIG. 2 is a diagram illustrating an example of an access network.

FIG. 3 is a diagram illustrating an example of a DL frame structure in LTE.

FIG. 4 is a diagram illustrating an example of an UL frame structure in LTE.

FIG. 5 is a diagram illustrating an example of a radio protocol architecture for the user and control planes.

FIG. 6 is a diagram illustrating an example of an evolved Node B and user equipment in an access network.

FIG. 7A is a diagram illustrating an example of an evolved Multimedia Broadcast Multicast Service channel configuration in a Multicast Broadcast Single Frequency Network.

FIG. 7B is a diagram illustrating a format of a Multicast Channel Scheduling Information Media Access Control control element.

FIG. 7C is a diagram illustrating MBMS over MBSFN areas within an MBMS service area.

FIG. 8 is a diagram for illustrating an exemplary method for adaptively configuring multicast broadcast service areas /MBSFN areas.

FIG. 9 is a diagram illustrating an exemplary architecture for adaptively configuring multicast broadcast service areas /MBSFN areas.

FIG. 10 is a diagram illustrating an exemplary signaling design for an adaptive MBSFN.

FIG. 11 is a diagram illustrating group call service through unicast, group, and MBMS bearers.

FIG. 12 is a diagram illustrating a group bearer establishment procedure.

FIG. 13 is a diagram illustrating a first exemplary bearer selection and establishment procedure.

FIG. 14 is a diagram illustrating a second exemplary bearer selection and establishment procedure.

FIG. 15 is a diagram of a PDU for sending group call communication through a group bearer.

FIG. 16 is an illustration of a system information block 15 (SIB 15) information element.

FIG. 17 is a diagram illustrating service continuity for a UE in idle mode.

FIG. 18 is a flow chart of a method of group call service communications.

FIG. 19 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus configured to implement the method of FIG. 18.

FIG. 20 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system configured to implement the method of FIG. 18.

FIG. 21 is a flow chart of a method of maintaining continuity of a group call service by a UE camped on a current cell in an idle mode.

FIG. 22 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus configured to implement the method of FIG. 21.

FIG. 23 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system configured to implement the method of FIG. 21.

FIG. 24 is a flow chart of a method of maintaining continuity of a group call service by a UE camped on a current cell in an idle mode.

FIG. 25 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus configured to implement the method of FIG. 24.

FIG. 26 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system configured to implement the method of FIG. 24.

FIG. 27 is a flow chart of a method of maintaining continuity of a group call service by a UE camped on a current cell in a connected mode.

FIG. 28 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus configured to implement the method of FIG. 27.

FIG. 29 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system configured to implement the method of FIG. 27.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs) , field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM) , a read-only memory (ROM) , an electrically erasable programmable ROM (EEPROM) , compact disk ROM (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an LTE network architecture 100. The LTE network architecture 100 may be referred to as an Evolved Packet System (EPS) 100. The EPS 100 may include one or more user equipment (UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 104, an Evolved Packet Core (EPC) 110, and an Operator’s Internet Protocol (IP) Services 122. The EPS can interconnect with other access networks, but for simplicity those entities/interfaces are not shown. As shown, the EPS provides packet-switched services, however, as those skilled in the art will readily appreciate, the various concepts presented throughout this disclosure may be extended to networks providing circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108, and may include a Multicast Coordination Entity (MCE) 128. The eNB 106 provides user and control planes protocol terminations toward the UE 102. The eNB 106 may be connected to the other eNBs 108 via a backhaul (e.g., an X2 interface) . The MCE 128 allocates time/frequency radio resources for evolved Multimedia Broadcast Multicast Service (MBMS) (eMBMS) , and determines the radio configuration (e.g., a modulation and coding scheme (MCS) ) for the eMBMS. The MCE 128 may be a separate entity or part of the eNB 106. The eNB 106 may also be referred to as a base station, a Node B, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , or some other suitable terminology. The eNB 106 provides an access point to the EPC 110 for a UE 102. Examples of UEs 102 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA) , a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player) , a camera, a game console, a tablet, or any other similar functioning device. The UE 102 may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

The eNB 106 is connected to the EPC 110. The EPC 110 may include a Mobility Management Entity (MME) 112, a Home Subscriber Server (HSS) 120, other MMEs 114, a Serving Gateway 116, a Multimedia Broadcast Multicast Service (MBMS) Gateway 124, a Broadcast Multicast Service Center (BM-SC) 126, and a Packet Data Network (PDN) Gateway 118. The MME 112 is the control node that processes the signaling between the UE 102 and the EPC 110. Generally, the MME 112 provides bearer and connection management. All user IP packets are transferred through the Serving Gateway 116, which itself is connected to the PDN Gateway 118. The PDN Gateway 118 provides UE IP address allocation as well as other functions. The PDN Gateway 118 and the BM-SC 126 are connected to the IP Services 122. The IP Services 122 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a PS Streaming Service (PSS) , and/or other IP services. The BM-SC 126 may provide functions for MBMS user service provisioning and delivery. The BM-SC 126 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a PLMN, and may be used to schedule and deliver MBMS transmissions. The MBMS Gateway 124 may be used to distribute MBMS traffic to the eNBs (e.g., 106, 108) belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

FIG. 2 is a diagram illustrating an example of an access network 200 in an LTE network architecture. In this example, the access network 200 is divided into a number of cellular regions (cells) 202. One or more lower power class eNBs 208 may have cellular regions 210 that overlap with one or more of the cells 202. The lower power class eNB 208 may be a femto cell (e.g., home eNB (HeNB) ) , pico cell, micro cell, or remote radio head (RRH) . The macro eNBs 204 are each assigned to a respective cell 202 and are configured to provide an access point to the EPC 110 for all the UEs 206 in the cells 202. There is no centralized controller in this example of an access network 200, but a centralized controller may be used in alternative configurations. The eNBs 204 are responsible for all radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway 116. An eNB may support one or multiple (e.g., three) cells (also referred to as a sectors) . The term “cell” can refer to the smallest coverage area of an eNB and/or an eNB subsystem serving a particular coverage area. Further, the terms “eNB, ” “base station, ” and “cell” may be used interchangeably herein.

The modulation and multiple access scheme employed by the access network 200 may vary depending on the particular telecommunications standard being deployed. In LTE applications, OFDM is used on the DL and SC-FDMA is used on the UL to support both frequency division duplex (FDD) and time division duplex (TDD) . As those skilled in the art will readily appreciate from the detailed description to follow, the various concepts presented herein are well suited for LTE applications. However, these concepts may be readily extended to other telecommunication standards employing other modulation and multiple access techniques. By way of example, these concepts may be extended to Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB) . EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. These concepts may also be extended to Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA； Global System for Mobile Communications (GSM) employing TDMA； and Evolved UTRA (E-UTRA) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. The use of MIMO technology enables the eNBs 204 to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different streams of data simultaneously on the same frequency. The data streams may be transmitted to a single UE 206 to increase the data rate or to multiple UEs 206 to increase the overall system capacity. This is achieved by spatially precoding each data stream (i.e., applying a scaling of an amplitude and a phase) and then transmitting each spatially precoded stream through multiple transmit antennas on the DL. The spatially precoded data streams arrive at the UE (s) 206 with different spatial signatures, which enables each of the UE(s) 206 to recover the one or more data streams destined for that UE 206. On the UL, each UE 206 transmits a spatially precoded data stream, which enables the eNB 204 to identify the source of each spatially precoded data stream.

Spatial multiplexing is generally used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions. This may be achieved by spatially precoding the data for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.

In the detailed description that follows, various aspects of an access network will be described with reference to a MIMO system supporting OFDM on the DL. OFDM is a spread-spectrum technique that modulates data over a number of subcarriers within an OFDM symbol. The subcarriers are spaced apart at precise frequencies. The spacing provides “orthogonality” that enables a receiver to recover the data from the subcarriers. In the time domain, a guard interval (e.g., cyclic prefix) may be added to each OFDM symbol to combat inter-OFDM-symbol interference. The UL may use SC-FDMA in the form of a DFT-spread OFDM signal to compensate for high peak-to-average power ratio (PAPR) .

FIG. 3 is a diagram 300 illustrating an example of a DL frame structure in LTE. A frame (10 ms) may be divided into 10 equally sized subframes. Each subframe may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including a resource block. The resource grid is divided into multiple resource elements. In LTE, for a normal cyclic prefix, a resource block contains 12 consecutive subcarriers in the frequency domain and 7 consecutive OFDM symbols in the time domain, for a total of 84 resource elements. For an extended cyclic prefix, a resource block contains 12 consecutive subcarriers in the frequency domain and 6 consecutive OFDM symbols in the time domain, for a total of 72 resource elements. Some of the resource elements, indicated as

R

302, 304, include DL reference signals (DL-RS) . The DL-RS include Cell-specific RS (CRS) (also sometimes called common RS) 302 and UE-specific RS (UE-RS) 304. UE-RS 304 are transmitted on the resource blocks upon which the corresponding physical DL shared channel (PDSCH) is mapped. The number of bits carried by each resource element depends on the modulation scheme. Thus, the more resource blocks that a UE receives and the higher the modulation scheme, the higher the data rate for the UE.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structure in LTE. The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

A UE may be assigned

resource blocks

410a, 410b in the control section to transmit control information to an eNB. The UE may also be assigned

resource blocks

420a, 420b in the data section to transmit data to the eNB. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. The UE may transmit data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may span both slots of a subframe and may hop across frequency.

A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (PRACH) 430. The PRACH 430 carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (1 ms) or in a sequence of few contiguous subframes and a UE can make a single PRACH attempt per frame (10 ms).

FIG. 5 is a diagram 500 illustrating an example of a radio protocol architecture for the user and control planes in LTE. The radio protocol architecture for the UE and the eNB is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer and implements various physical layer signal processing functions. The L1 layer will be referred to herein as the physical layer 506. Layer 2 (L2 layer) 508 is above the physical layer 506 and is responsible for the link between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control (MAC) sublayer 510, a radio link control (RLC) sublayer 512, and a packet data convergence protocol (PDCP) 514 sublayer, which are terminated at the eNB on the network side. Although not shown, the UE may have several upper layers above the L2 layer 508 including a network layer (e.g., IP layer) that is terminated at the PDN gateway 118 on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc. ) .

The PDCP sublayer 514 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 514 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between eNBs. The RLC sublayer 512 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ) . The MAC sublayer 510 provides multiplexing between logical and transport channels. The MAC sublayer 510 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNB is substantially the same for the physical layer 506 and the L2 layer 508 with the exception that there is no header compression function for the control plane. The control plane also includes a radio resource control (RRC) sublayer 516 in Layer 3 (L3 layer) . The RRC sublayer 516 is responsible for obtaining radio resources (e.g., radio bearers) and for configuring the lower layers using RRC signaling between the eNB and the UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650 in an access network. In the DL, upper layer packets from the core network are provided to a controller/processor 675. The controller/processor 675 implements the functionality of the L2 layer. In the DL, the controller/processor 675 provides header compression, ciphering, packet segmentation and reordering, multiplexing between logical and transport channels, and radio resource allocations to the UE 650 based on various priority metrics. The controller/processor 675 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the UE 650.

The transmit (TX) processor 616 implements various signal processing functions for the L1 layer (i.e., physical layer) . The signal processing functions include coding and interleaving to facilitate forward error correction (FEC) at the UE 650 and mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK) , quadrature phase-shift keying (QPSK) , M-phase-shift keying (M-PSK) , M-quadrature amplitude modulation (M-QAM) ) . The coded and modulated symbols are then split into parallel streams. Each stream is then mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 674 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 650. Each spatial stream may then be provided to a different antenna 620 via a separate transmitter 618TX. Each transmitter 618TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through its respective antenna 652. Each receiver 654RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 656. The RX processor 656 implements various signal processing functions of the L1 layer. The RX processor 656 may perform spatial processing on the information to recover any spatial streams destined for the UE 650. If multiple spatial streams are destined for the UE 650, they may be combined by the RX processor 656 into a single OFDM symbol stream. The RX processor 656 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT) . The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the eNB 610. These soft decisions may be based on channel estimates computed by the channel estimator 658. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the eNB 610 on the physical channel. The data and control signals are then provided to the controller/processor 659.

The controller/processor 659 implements the L2 layer. The controller/processor can be associated with a memory 660 that stores program codes and data. The memory 660 may be referred to as a computer-readable medium. In the UL, the controller/processor 659 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the core network. The upper layer packets are then provided to a data sink 662, which represents all the protocol layers above the L2 layer. Various control signals may also be provided to the data sink 662 for L3 processing. The controller/processor 659 is also responsible for error detection using an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets to the controller/processor 659. The data source 667 represents all protocol layers above the L2 layer. Similar to the functionality described in connection with the DL transmission by the eNB 610, the controller/processor 659 implements the L2 layer for the user plane and the control plane by providing header compression, ciphering, packet segmentation and reordering, and multiplexing between logical and transport channels based on radio resource allocations by the eNB 610. The controller/processor 659 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the eNB 610.

Channel estimates derived by a channel estimator 658 from a reference signal or feedback transmitted by the eNB 610 may be used by the TX processor 668 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 668 may be provided to different antenna 652 via separate transmitters 654TX. Each transmitter 654TX may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar to that described in connection with the receiver function at the UE 650. Each receiver 618RX receives a signal through its respective antenna 620. Each receiver 618RX recovers information modulated onto an RF carrier and provides the information to a RX processor 670. The RX processor 670 may implement the L1 layer.

The controller/processor 675 implements the L2 layer. The controller/processor 675 can be associated with a memory 676 that stores program codes and data. The memory 676 may be referred to as a computer-readable medium. In the UL, the controller/processor 675 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the UE 650. Upper layer packets from the controller/processor 675 may be provided to the core network. The controller/processor 675 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

FIG. 7C is a diagram 780 illustrating MBMS over MBSFN areas within an MBMS service area. FIG. 7C illustrates a system including an MBMS service area 732 encompassing

multiple MBSFN areas

734, 736, 738, which themselves include multiple cells or base stations 740. As used herein, an “MBMS service area” refers to a group of wireless transmission cells where a certain MBMS service is available. For example, a particular sports or other program may be broadcast by base stations within the MBMS service area at a particular time. The area where the particular program is broadcast defines the MBMS service area. The MBMS service area may be made up of one or more “MBSFN areas” as shown at 734, 736 and 738. As used herein, an MBSFN area refers to a group of cells (e.g., cells 740) currently broadcasting a particular program in a synchronized manner using an MBSFN protocol. An “MBSFN synchronization area” refers to a group of cells that are interconnected and configured in a way such that they are capable of operating in a synchronized fashion to broadcast a particular program using an MBSFN protocol, regardless of whether or not they are currently doing so. Each eNB can belong to only one MBSFN synchronization area, on a given frequency layer. It is worth noting that an MBMS service area 732 may include one or more MBSFN synchronization areas (not shown) . Conversely, an MBSFN synchronization area may include one or more MBSFN areas or MBMS service areas. Generally, an MBSFN area is made up of all, or a portion of, a single MBSFN synchronization area and is located within a single MBMS service area. Overlap between various MBSFN areas is supported, and a single eNB may belong to several different MBSFN areas. For example, up to 8 independent MCCHs may be configured in System Information Block (SIB) 13 to support membership in different MBSFN areas. An MBSFN Area Reserved Cell or Base Station is a cell/base station within a MBSFN Area that does not contribute to the MBSFN transmission, for example a cell near a MBSFN Synchronization Area boundary, or a cell that that is not needed for MBSFN transmission because of its location.

With an increase in eMBMS popularity, adaptively configuring multicast broadcast service areas (e.g., MBSFN service areas, MBMS service areas) or MBSFN areas based on available resources and user distribution could be beneficial. Through the adaptive configuration of multicast broadcast service areas /MBSFN areas, cells may be added or removed according to actual needs. By allowing the adaptive configuration of multicast broadcast service areas /MBSFN areas, system resource utilization may be increased, easy of operations/configurations may be improved, interference may be reduced through the use of tiers, and eMBMS may be provided on demand when a sufficient number of users desire the same service.

FIG. 8 is a diagram 800 for illustrating an exemplary method for adaptively configuring multicast broadcast service areas /MBSFN areas. As shown in FIG. 8, a multicast broadcast service area 812 may include cells 802-810 corresponding to the

eNBs

802a, 802b, 802c, 802d, 804a, 804b, 804c, 806a, 808a, and 810a. One or more of the eNBs within the multicast broadcast service area 812 may determine UE count information indicating a number of UEs served by the eNBs. Each of the one or more of the eNBs then sends the UE count information to a network entity, such as a Multicast Coordination Entity (MCE) or a BM-SC. Each of the one or more of the eNBs may also receive signal quality information from each of the UEs served by the corresponding eNB. The signal quality information is with respect to the serving base station and neighboring base stations. For example, the eNB 802b may receive signal quality information from each of the

UEs

820, 822, 824. The signal quality information may be with respect to unicast transmissions and/or multicast/broadcast transmissions and may include at least one of reference signal received power (RSRP) information, reference signal received quality (RSRQ) information, a receive strength signal indicator (RSSI) , or a signal to interference plus noise ratio (SINR) . Accordingly, the eNB 802b may receive signal quality information from the UE 820 based on unicast and/or multicast/broadcast transmissions from the

eNBs

802b, 804b, 804c； from the UE 822 based on unicast and/or multicast/broadcast transmissions from the

eNBs

802b, 804c, 806a； and from the UE 824 based on unicast and/or multicast/broadcast transmissions from the

eNBs

802b, 802c, 802d. Each of the one or more of the eNBs then sends the signal quality information to the network entity, such as the MCE or the BM-SC.

Based on the UE count information, the MCE or BM-SC determines whether a base station should be part of the multicast broadcast service area 812 and/or an MBSFN area within the multicast broadcast service area 812. The MCE or BM-SC may make the determination further based on the received signal quality information. For example, upon receiving the UE count information and signal quality information, the MCE or BM-SC may determine that the eNB 804c should be part of the multicast broadcast service area 812 and/or be a part of an MBSFN area within the multicast broadcast service area 812. The MCE or BM-SC may make such a determination based on providing MBSFN (MBMS) services for any UEs served by the eNB 804c, such as the UE 826, or based on providing improved (e.g., improved RSRP, RSRQ, RSSI, SINR) MBSFN services for any UEs on the cell edge of the eNB 804c, such as for the

UEs

820, 822. Specifically, the MCE or BM-SC may determine based on the UE count information that a sufficient number of UEs within the coverage of the eNB 804c, such as the UE 826, would like to receive MBSFN services from the eNB 804c. Furthermore, the MCE or BM-SC may determine based on the UE count information that a sufficient number of UEs, such as the

UEs

820, 822, reported a signal quality from the eNB 802b less than a first quality threshold and a signal quality from the eNB 804c greater than a second quality threshold. The MCE or BM-SC may then determine that the

UEs

820, 822 are on the edge of the cells between the eNBs 802b, 804c, and may therefore benefit from receiving MBSFN services from the eNB 804c.

As shown in FIG. 8, the cells 802 (i.e., the set of cells 814) within the multicast broadcast service area 812 are statically configured and therefore the multicast broadcast service area configuration and the MBSFN area of each of the cells 802 may not be adapted or changed dynamically. However, the

cells

804, 806, 808, 810 (i.e., the set of cells 816) within the multicast broadcast service area 812 are adaptively configured and therefore the multicast broadcast service area configuration and/or the MBSFN area of each of the

cells

804, 806, 808, 810 may be adapted or changed dynamically. Upon receiving the UE count information and the signal quality information, the MCE or BM-SC may rank the adaptively configured eNBs 816 based on the UE count information and the signal quality information. For example, the MCE or BM-SC may rank an adaptively configured eNB higher if the adaptively configured eNB serves a sufficient number of UEs that would like to receive MBSFN services and/or would improve the signal quality of a sufficient number of UEs on a cell edge of the adaptively configured eNB. In one configuration, the eNBs within the multicast broadcast service area 812 perform the ranking and send ranked list information to the MCE or BM-SC. Based on the ranked adaptively configured eNBs 816, the MCE or BM-SC determines which eNBs should be part of the multicast broadcast service area 812 and/or part of particular MBSFN areas. The MCE or BM-SC then sends information to the eNBs indicating whether the eNBs should be part of the multicast broadcast service area 812 and/or particular MBSFN areas.

The MCE or BM-SC may also determine a broadcasting tier for the eNB upon determining the eNB should be part of the multicast broadcast service area 812 and/or particular MBSFN areas. The broadcasting tier may be a first tier (tier 1) 840 for broadcasting a system information block (SIB) indicating an MCCH configuration for the MCCH； a second tier (tier 2) 842 for broadcasting the SIB indicating the MCCH configuration for the MCCH and broadcasting the MCCH indicating an MTCH configuration； or a third tier (tier 3) 844 for broadcasting the SIB indicating the MCCH configuration for the MCCH, broadcasting the MCCH indicating the MTCH configuration, and broadcasting the MTCH. The tiers allow for particular adaptive eNBs to be configured to provide different levels of MBSFN services. For example, if an adaptive eNB serves many UEs interested in receiving MBSFN services or the broadcasting of the MTCH would improve cell edge UEs served by other eNBs, the adaptive eNB may be configured in tier 3. However, if the adaptive eNB serves few or no UEs and the broadcasting of the MTCH would provide no to little improvement to cell edge UEs served by other eNBs, the adaptive eNB may be configured in tier 2 or tier 1. As shown in FIG. 8, based on the UE count information and the signal quality information, the MCE or BM-SC determined that the

eNBs

804a, 804b, 804c should provide tier 3 844 MBSFN services, the eNB 806a should provide tier 2 842 MBSFN services, the eNB 808a should provide tier 1 840 MBSFN services, and the eNB 810a should not be a part of the multicast broadcast service area 812 and/or provide MBSFN services (846) . Upon determining the broadcasting tier for the eNBs, the MCE or BM-SC sends information to the eNBs indicating their MBSFN broadcasting tier.

When the MCE /BM-SC determines that an adaptive eNB should not be a part of the multicast broadcast service area 812, the multicast broadcast service area decreases in size. When the MCE /BM-SC determines that an adaptive eNB should be a part of the multicast broadcast service area 812, the multicast broadcast service area increases in size. As such, the determination of whether adaptive eNBs should be part of the multicast broadcast service area 812 ultimately changes the size of the multicast broadcast service area 812, usually on the edges of the multicast broadcast service area 812. As discussed supra, each multicast broadcast service area 812 may support up to eight MBSFN areas. When the MCE /BM-SC determines that an adaptive eNB should not be a part of an MBSFN area of the multicast broadcast service area 812, the multicast broadcast service area 812 may not change in size. Instead, the services provided by one of the cells in the multicast broadcast service area 812 changes. The adaptive multicast broadcast service area and adaptive MBSFN areas allow for areas associated with MBSFN /MBMS services to change based on UE mobility, UE multicast broadcast service interest, multicast broadcast reception quality improvement, etc.

FIG. 9 is a diagram 900 illustrating an exemplary architecture for adaptively configuring multicast broadcast service areas /MBSFN areas. UEs are instructed by serving eNBs to measure and to report measurement report messages (MRMs) about the serving eNB and surrounding/neighboring eNBs. The UEs may also report on whether they would like to receive MBSFN services or particular MBSFN services. The UEs send the information within the input I1 to the eNBs. The input I1 includes MRMs and information for obtaining a count of UEs (i.e., UE count information) interested in MBSFN services or particular MBSFN services. The MRMs may include radio frequency (RF) results, such as RSRP, RSRQ, RSSI, or SINR measurements. The MRMs may further include a list of cells (e.g., physical cell identities (PCIs) ) . The eNBs receive the input I1 from the UEs.

In logical function LF1, the eNBs may extract RF measurements, obtain the list of cells, and determine a count of UEs (i.e., UE count information) that would like to receive MBSFN services or particular MBSFN services. The eNBs may then rank the list of cells. In the logical function LF2, the eNBs may transmit elaborated information to the MCE and receive an updated configuration for the multicast broadcast service area and/or MBSFN areas. The elaborated information may include the RF measurements, list of cells, and the UE count information. Alternatively or additionally, the elaborated information may include the ranked list of cells. The eNBs send input I2 to the MCE. The input I2 includes candidate neighbors, including RF statistics and observed sets. In logical function LF3, the MCE receives the list information, executes MBSFN area optimization algorithms to maximize a goal function for adjusting to the network load and MBMS user distribution, and transmits updated cluster sets (i.e., multicast broadcast service area and/or MBSFN area configurations) back to the eNBs indicating whether the eNBs should be part of the multicast broadcast service area and/or part of particular MBSFN areas.

FIG. 10 is a diagram 1000 illustrating an exemplary signaling design for an adaptive MBSFN. As shown in FIG. 10, in step 1002, the MME sends a session start request to the MCE. In step 1004, the MCE responds by sending a session start response to the MME. In step 1006, the MCE sends an M2 interface setup request to the eNB1. In step 1008, the eNB1 responds by sending an M2 interface setup response to the MCE. In step 1010, in response to receiving the M2 setup request, the eNB1 obtains UE measurement reports and UE count information indicating a number of UEs served by the eNB1 that are interested in receiving MBSFN services and/or particular MBSFN services, and sends the UE measurement reports and UE count information to the MCE. Based on the received information, the MCE then determines whether particular eNBs should be part of the multicast broadcast service area and/or part of particular MBSFN areas. In step 1012, the MCE sends an MCE configuration update to the eNB1 and receives an MCE configuration update response from the eNB1. In step 1014, the MCE sends MBMS scheduling information to the eNB1. The MBMS scheduling information may include an MBSFN area identifier (ID) , PMCH configuration information, and a reserved cell indication. The MCE may send information, explicitly or implicitly, to the eNB1 indicating an adapted MBSFN configuration in relation to the multicast broadcast service area and/or MBSFN areas within the MCE configuration update in step 1012 or the MBMS scheduling information in step 1014. In one configuration, the adaptive MBSFN configuration information may be sent, explicitly or implicitly, within the M2 setup request in step 1006, assuming the measurement report and counting procedures of step 1010 is performed before step 1006. In another configuration, the adaptive MBSFN configuration information may be sent, explicitly or implicitly, within an eNB configuration update acknowledgment. In step 1016, the eNB1 sends an MBMS scheduling information response to the MCE. In step 1018, the MCE sends a session start request to the eNB1. In step 1020, the MCE receives a session start response from the eNB1. In step 1022, the MCE repeats steps 1006 through 1016 with the eNB2. In step 1024, the MCE may receive UE count information from the MME in a backend counting procedure in which UE count information is received from the MME. The MCE may use the UE count information from the eNBs and/or the MME when determining the adaptive MBSFN configuration for each of the adaptive eNBs.

FIG. 11 is a diagram 1100 illustrating group call service through unicast, group, and MBMS bearers. As shown in FIG. 11, a PoC server 1102 receives an IP packet from a UE 1110 from a unicast channel through an eNB, P-GW/SGW. The PoC server 1102 sends a unicast IP packet to a BM-SC 1104 over an IMS. The BM-SC 1104 sends the IP packet (referred to now a multicast/broadcast IP packet) through an SG-imb interface to an MBMS-GW 1106. The MBMS-GW 1106 forwards the multicast/broadcast IP packet through an M1 interface to an eNB 1108. The signaling is between the BM-SC 1104 and the MBMS-GW 1106 through an SGmb interface, between the MBMS-GW 1106 and an MME through an Sm interface, between the MME and the MCE 1108 through an M3 interface, and between the MCE 1108 and the eNB 1108 through an M2 interface. The eNB 1108 broadcasts the multicast/broadcast IP packet to the UEs 1112 as an eMBMS service carried on a corresponding MTCH.

Furthermore, as shown in FIG. 11, the PoC server 1102 sends a unicast IP packet to a P-GW 1120 over an IMS. The P-GW 1120 sends the unicast IP packet to an SGW 1122. The SGW 1122 sends the unicast IP packet to an eNB/MME 1124, which sends the unicast IP packet through a group bearer to the UEs 1126. In addition, the SGW 1122 sends the unicast IP packet to the eNB/MME 1128, which sends the unicast IP packet through a unicast bearer to the UE 1130. In an exemplary configuration, a UE may be able to receive a group call service communication through a group bearer. A UE may indicate to the network whether the UE is capable of receiving group call service communication through one or more of a unicast bearer, a group bearer, and an MBMS bearer. When the network receives a group call service communication, the network may determine whether to utilize unicast, group, and/or MBMS bearers to deliver the group call service communication. The network may make such a determination based on the bearer capabilities of the target UEs (i.e., intended recipients of the group call service communication) , a number of the target UEs (i.e., a UE group size) , whether file repair is needed, the type of the group call service communication, the importance of the group call service communication, etc. For example, if the group size is small, the group call service communication is important, or the group call service communication may require file repair (e.g., software upgrade) , the network may determine to send the group call service communication through a unicast bearer. For another example, if the group size is large, the group call service communication is less important, no retransmissions of the group call service communication are desired, or the group call service communication is voice or live video, the network may determine to send the group call service communication through an MBMS bearer. For another example, if the group size is between small and large, the network may determine to send the group call service communication through a group bearer (or multiple group bearers) .

FIG. 12 is a diagram 1200 illustrating a group bearer establishment procedure. In step 0, the PoC /machine type communication (MTC) server receives a group call setup request for a multicast/broadcast data transmission. In one example, the multicast/broadcast data transmission is a group call service communication. In step 1, the PoC /MTC server sends a group bearer request to a group gateway (Group- GW). The Group-GW queries a home subscriber server (HSS) for serving MMEs of the target UEs and assigns a multicast IP and general packet radio service (GPRS) tunneling protocol user plane (GTP-U) tunnel. In step 2, the Group-GW sends requests to the MMEs to create a group bearer. The requests may include the multicast IP, the GTP-U tunnel information, a group identifier (ID) identifying the group bearer, quality of service (QoS) information, and target UEs.

In step 3, each of the MMEs establish group bearers locally, and send a group bearer assignment request to the associated eNBs in order to establish group bearers in the eNBs serving the target UEs. The eNBs establish the group bearer context for the group bearer. The group bearer parameters (also referred to as group bearer context information) include one or more of a bearer ID, the group ID, a group RNTI (G-RNTI) , a list of target UEs, an RLC /PDCP configuration, QoS profile, an IP address, and a receiving type. The group bearer parameters may additionally include a discontinuous reception (DRX) configuration. The receiving type, which is discussed further infra, may be one of connected, hybrid, or idle.

In step 4, each eNB responds to their associated MME with a group bearer assignment response. In step 5, each eNB sends paging to the group. The paging message includes the G-RNTI, the group ID, and the receiving type. In step 6, if a UE belongs to the group corresponding to the group ID, the UE receives the group bearer parameters in a message on a common control channel (CCCH) or a physical downlink shared channel (PDSCH) from a serving eNB. The message including the group bearer parameters is scrambled based on the G-RNTI. The message further includes information for obtaining the multicast/broadcast data transmission on the PDSCH.

In step 7, depending on the receiving type, the target UEs that receive the paging and descramble the message including the group bearer parameters, may enter a connected mode (i.e., an RRC connected state) by a service request procedure, remain in a connected mode, change to an idle mode, or remain in an idle mode. Thereafter, UE group bearer context is established. In step 8, each MME sends a create group bearer response to the Group-GW. In step 9, the Group-GW sends a group bearer response to the PoC/MTC server. Thereafter, the UE may receive the multicast/broadcast data transmission through the established group bearer on the PDSCH from the eNB.

As discussed supra, the receiving type may be connected, hybrid, or idle. If the receiving type is connected, target UEs should be in an RRC connected state to receive the multicast/broadcast data transmission. UEs in an RRC connected state may report CQI to the serving eNB. The serving eNB receives the CQI from the target UEs, determines an MCS based on the received CQI, and sends the multicast/broadcast data transmission at the determined MCS. In a first configuration, the serving eNB determines a worst CQI (i.e., a CQI corresponding to a lowest MCS) and sends the multicast/broadcast data transmission at an MCS corresponding to the worst CQI. Accordingly, all of the target UEs may receive the multicast/broadcast data transmission, as the multicast/broadcast data transmission is sent with an MCS that allows the target UEs with the worst received signal quality to be able to decode successfully the multicast/broadcast data transmission. In a second configuration, the serving eNB determines an MCS that would allow a particular percentage of the target UEs to receive the multicast/broadcast data transmission, and sends the multicast/broadcast data transmission at that MCS. In the second configuration, the serving eNB may send the multicast/broadcast data transmission with a higher MCS than in the first configuration.

If the receiving type is idle, target UEs do not send CQI feedback in relation to the multicast/broadcast data transmission. The target UEs may send CQI feedback for other purposes, such as for example, because the target UEs are in an RRC connected state. That is, if the receiving type is idle, target UEs in an RRC idle state need not change to an RRC connected state to receive the multicast/broadcast data transmission. In addition, target UEs in an RRC connected state need not maintain the RRC connected state to receive the multicast/broadcast data transmission. Furthermore, serving eNBs do not take into account received CQI (e.g., from target UEs in an RRC connected state) when sending the multicast/broadcast data transmission to the target UEs. Serving eNBs may send the multicast/broadcast data transmission at a low MCS or a lowest possible MCS so that a sufficient number of target UEs receive the multicast/broadcast data transmission.

If the receiving type is hybrid (i.e., a hybrid of the idle and connected receiving types) , target UEs need not enter an RRC connected state to receive multicast/broadcast data transmission. However, if a target UE has a receiving signal quality less than a signal quality threshold (e.g., RSRP, RSRQ, RSSI, or SINR is less than a threshold) , the target UE may enter an RRC connected state in order to provide CQI feedback to the serving eNB. The serving eNB takes into account CQI received from target UEs when determining an MCS for sending the multicast/broadcast data transmission. The serving eNB may indicate the signal quality threshold at which a target UE should enter an RRC connected state within the group bearer parameters (provided in step 6) . Accordingly, target UEs with a received signal quality less than the signal quality threshold may enter an RRC connected state, and target UEs with a received signal quality greater than the signal quality threshold need not enter into an RRC connected state. A target UE may use a cell reselection parameter (e.g., Sintersearch) as the signal quality threshold. Even if the receiving signal quality is greater than the signal quality threshold, target UEs may change to an RRC connected state when a cell change is needed (for example, a handover to another cell) .

When the receiving type is connected or hybrid and a target UE is in an RRC connected state, the target UE reports CQI, and additionally may report an ACK and/or NACK so that the serving eNB can schedule the group bearer to ensure reception quality. When the serving eNB receives a NACK, the serving eNB re-transmits the multicast/broadcast data transmission packet that was not properly received. Using a packet switched handover (PSHO) procedure, the serving eNB can hand over a UE to a target cell when necessary. As part of the handover, the serving eNB may send the group bearer context information to the target cell. When the receiving type is idle and a UE enters a cell without a current interest in receiving multicast/broadcast data transmission, the UE may initiate a service request procedure to request a group bearer establishment.

With respect to sending ACK/NACKs by the UE, in an implicit ACK/NACK resource mapping rule, all UEs send ACK/NACK on the same resource in UL, which may result in an ACK/NACK collision. A semi-static configuration may be used to specify ACK/NACK resources for each UE. However, when multiple UEs are in the same group, multiple ACK/NACK resources need to be allocated. In one configuration, if one UE within a group fails to receive a multicast/broadcast data transmission packet, the serving eNB will retransmit the multicast/broadcast data transmission packet to all the UEs in the group. The serving eNB may configure UEs to use PUCCH format 1 for sending ACK/NACK. Accordingly, UEs that successfully decode the multicast/broadcast data transmission packet will not ACK, and UEs that fail to decode the multicast/broadcast data transmission packet will send a NACK on the same ACK/NACK resource according to an implicit mapping rule on the first control channel element (CCE) index in the PDCCH associated with the G-RNTI. The ACK/NACK resource may be associated with a PDCCH used for scheduling the multicast/broadcast data transmission. As the NACKs are sent on the same resource, the serving eNB will receive the NACK with an SFN gain when more than one UE transmits the ACK. When the serving eNB receives a NACK, the serving eNB retransmits the multicast/broadcast data transmission packet. If there is DTX on the ACK/NACK resource (i.e., no NACK is received) , the serving eNB assumes that all the UEs successfully decoded the multicast/broadcast data transmission packet. The ACK/NACK procedure reduces UL ACK/NACK overhead, as only a single ACK/NACK resource is used per group. Further, NACKs have a SFN gain from multiple users, leading into enhanced ACK/NACK detection.

The ACK/NACK procedure provided supra provides for a more efficient ACK/NACK resource utilization, but with a less efficient retransmission, as a NACK from any UEs in a group with respect to a particular packet results in a retransmission of that particular packet to all the UEs in the group. Alternatively, the serving eNB may utilize network coding ARQ (NC-ARQ) during retransmissions. Accordingly, the retransmission packet may be a function of multiple packets. For example, assume the serving eNB transmits first and second multicast/broadcast data transmission packets, and a first UE is unable to decode successfully the first multicast/broadcast data transmission packet, and the second UE is unable to decode successfully the second multicast/broadcast data transmission packet. The first UE will send a NACK to indicate that the UE was unable to decode the first multicast/broadcast data transmission packet, and the second UE will send a NACK to indicate that the UE was unable to decode the second multicast/broadcast data transmission packet. The serving eNB may combine the first and second multicast/broadcast data transmission packets (e. g., through XOR) , and send the combined multicast/broadcast data transmission packet to the first and second UEs. Assume each of the first and second UEs are able to decode the combined multicast/broadcast data transmission packet. The first UE may obtain the first multicast/broadcast data transmission packet based on the second multicast/broadcast data transmission packet and the combined multicast/broadcast data transmission packet, and the second UE may obtain the second multicast/broadcast data transmission packet based on the first multicast/broadcast data transmission packet and the combined multicast/broadcast data transmission packet. As demonstrated in the example, NC-ARQ provides for a more efficient eNB retransmission, but with a less efficient ACK/NACK resource utilization. Utilizing NC-ARQ allows the UE to be aware of ACK/NACK status from each individual UE on an RLC level.

ACK and CQI may be transmitted simultaneously. When a UE in the group needs to transmit ACK and CQI simultaneously, modulated RS may be used for normal CP and joint coding may be used for extended CP. UEs that transmit ACK/NACK and CQI simultaneously do not use a PUCCH format 1 message. With group NACK, UEs within the group send NACK on the same resource if they are not scheduled to send CQI. Otherwise if UEs are scheduled to send CQI, the UEs send individual regular ACK/NACK together with CQI on a corresponding CQI resource. The serving eNB detects ACK/NACK from those UEs that are scheduled to send CQI at the same time. Retransmission depends on group NACK detection in addition to individual ACK/NACK on CQI.

As discussed supra, when UEs are in an RRC connected state, the UEs feedback CQI, and when the receiving type is connected or hybrid, the serving eNB may take into account the received CQI when scheduling the group transmission. For example, the serving eNB may send the multicast/broadcast data transmission based on the worst CQI. In one configuration, UEs need not provide CQI feedback if the CQI is greater than a CQI threshold. In such a configuration, if the serving eNB does not receive CQI feedback, the serving eNB may send the multicast/broadcast data transmission based on an MCS corresponding to the CQI threshold, and if the serving eNB receives CQI feedback, the serving eNB may send the multicast/broadcast data transmission based on the worst CQI feedback. Based on previous CQI feedback and/or a measurement report, a serving eNB may reconfigure UEs with different CQI feedback configurations (e.g., CQI feedback periods) . A serving eNB may configure high geometry UEs (i.e., UEs with high signal quality, smaller path loss) to provide CQI feedback less often compared to low geometry UEs (i.e., UEs with a low signal quality, higher path loss) . With individual ACK/NACK feedback, the serving eNB can schedule UEs with NACK feedback to transmit CQI and UEs without NACK feedback not to transmit CQI. Multiple UEs may be scheduled for CQI transmissions on the same resource. UEs that fail to decode may transmit CQI and/or UEs that have a CQI lower than the CQI threshold may transmit CQI. UEs may receive the CQI threshold from an eNB in the PDCCH or in an L3 message, such as through RRC signaling.

All UEs within a group bearer can be configured with rank 1 transmissions in which the UEs do not need to send rank information (RI) . When multiple UEs are configured in the group bearer, the serving eNB may configure the UEs with a transmit diversity (TxD) mode. In the TxD mode, UEs may use a space-frequency block code (SFBC) with two eNB transmit antennas or SFBC + frequency switched transmit diversity (FSTD) with four eNB transmit antennas to compute CQI feedback. In TxD mode, UEs need not send precoding matrix indicator (PMI) feedback. A serving eNB may schedule (transmit to) UEs using MU-MIMO mode. For MU-MIMO, a UE may compute CQI and PMI and send the CQI/PMI to the serving eNB. ACK/NACK feedback may be according to regular unicast procedure. A UE can further report CQI based on TxD in case the serving eNB cannot pair the UEs in MU-MIMO mode.

With respect to DRX, UEs follow a group DRX configuration when the group bearer is activated. A serving eNB may schedule regular unicast traffic as well as group traffic in the On Duration of the group DRX configuration. PDCCH load may be increased, as the serving eNB may serve more UEs in the On Duration given that all UEs within the same group follow the group DRX configuration. When a group bearer is deactivated, UEs may follow a non-group DRX configuration if configured.

Disclosed further herein are concepts and features of group call services (GCS) relating to transmission types, e.g., unicast (UC) , point-to-multipoint (PTM) or a multimedia broadcast service (MBMS) transmission type and the associated unicast (UC) bearer, group bearer, and/or MBMS bearer for sending group call messages. Group call messages may also be referred to herein as GCS messages, group call communication, or GCS communications. Concepts further relate to decisions regarding which bearer to establish based on information received from UEs that are interested in a group call service. Features related to implementing a group call service, including PTM configuration content and delivery for PTM transmissions, and synchronization protocols for sending GCS messages are described.

As described above, PTM transmission through a group bearer may be used in cases where a group size of UEs is between small and large, the GCS communication is less important, no retransmissions of the GCS communication are desired, or the communication is voice or live video. An example of a group bearer is SC-PTM. It is complementary to MBMS MRB and may be useful, e.g., when: inter-eNB synchronization is not available, or interested UEs are in disjoint cells of a MBSFN area, CQI reporting can be enabled for better adaption to radio conditions, and retransmission can be supported for better reliability compared with single cell MBSFN. Disclosed herein are SC-PTM content and delivery methods.

Transmission Type and Bearer Decisions

A network may decide to use UC, PTM, or MBMS transmissions and corresponding bearers based on the distribution of a set of UEs relative to a cell that is available to provide a group call service, e.g., send group call messages or communications. The distribution of UEs may be determined based on information obtained from the UEs. For example, a UE may send one or more of a counting report, or a location and interest report, or a capability report to the network, or a consumption report. One or more of these reports may include information indicating the serving cell identity of the UE, the RAN capability of the UE, transmission type capability of the UE, e.g., does the UE support MBMS, PTM or both MBMS and PTM. In the case of PTM support, the reports sent by the UE may further indicate the transmission mode capability of the UE.

Decision to use Unicast

In one aspect, a decision to use UC may be determined by a group communication system enablers application server (GCSE-AS) that provides a group call service. For example, the GCSE-AS may determine based on location information included in reports sent from a set of UEs and received by the GCSE-AS that only one UE in the set of UEs is being served by a particular cell. Accordingly, the GCSE-AS may determine to provide the group call service to that particular UE using unicast transmission through a unicast bearer.

In a second aspect, a decision to use UC may be determined by the RAN. For example, the MME may determine based on location information included in reports sent from a set of UEs and received by the MME that only one UE in the set of UEs is being served by a particular cell. Accordingly, the MME may determine to provide the group call service to that particular UE using unicast transmission through a unicast bearer.

Decision to use PTM or MBMS

In a first aspect of deciding between PTM and MBMS, a GCSE-AS or a broadcast network entity, e.g., BM-SC, may decide between the use of one or both of a PTM transmission type with corresponding group bearer, and a MBMS transmission type and corresponding MBMS bearer (or single cell SFN) based on information of UEs in a set of UEs interested in the group call service. A PTM transmission type may be a single cell point-to-multipoint (SC-PTM) transmission or a multicell point-to-multipoint (MC-PTM) transmission. A MBMS transmission type may be a single site MBMS transmission or a multisite MBMS transmission.

A UE in the set of UEs interested in the group call service may be referred to as a target UE. The information of the target UEs may be the type of information included in one or more of the various UE reports described above, and may include UE location information. The GCSE-AS may receive the UE reports through application layer signaling, while the BM-SC may receive the UE reports through service layer signaling. RAN capability may also be reported to the GCSE-AS or BM-SC, or known by the GCSE-AS/BM-SC through pre-configuration via OAM.

When the network receives a group call communication, the GCSE-AS or BM-SC may determine whether to utilize group, and/or MBMS bearers to deliver the communication. The GCSE-AS/BM-SC may make such a determination based on the bearer capabilities of the target UEs, a number of the target UEs, whether file repair is needed, the type of the group call service associated with the communication, the importance of the communication, etc. For example, if the group size is large, the communication is less important, no retransmissions of the communication are desired, or the communication is voice or live video, the GCSE-AS or BM-SC may determine to send the communication through an MBMS bearer. If the group size is between small and large, the GCSE-AS or BM-SC may determine to send the group call communication through a group bearer.

With respect to service continuity, when a UE that is receiving group call communication through a MBMS bearer or group bearer is moved in or out of coverage of the corresponding MBMS bearer are or group bearer area, the UE notifies the GCSE-AS or BM-SC. For example, when UE is moved out of a MBMS bearer coverage area or a group bearer coverage area, the UE may establish a UC bearer with a cell that provides the group call service. When the UE is moved into a MBMS bearer coverage area or a group bearer coverage area that provides the group call service, the UE may continue to receive group call communications through the UC bearer until an MBMS bearer or PTM bearer is established.

FIG. 13 is a diagram 1300 illustrating a first exemplary bearer selection and establishment procedure. At 1, a TMGI is allocated for a group call by one of a BM-SC or a GCSE-AS. At 2, one or both of the BM-SC and the GCSE-AS receive information from one or more UEs. The information may be in the form of one or more of a counting report, or a location and interest report, or a capability report to the network, or a consumption report. A UE may be triggered to send a report when the UE is interested in a group call service, the UE is already in a group call, or the UE moves to a different location, e.g., the UE is moved from one cell to another cell. The UE may report based on configuration received from the GCSE-AS or BM-SC.

At 3, either of the BM-SC or a GCSE-AS decides to use a PTM transmission or an MBMS transmission. An MBMS transmission may be made over a multi cell MBSFN. The decision of which type or mode of transmission to use may be made as described above. At 4, the BM-SC or a GCSE-AS activates or establishes an MBMS bearer for sending group communication to target UEs for which an MBMS transmission type was determined.

At 5, the BM-SC initiates a session start procedure. The session start or session establishment procedure may be based on 3GPP TS 23.246, with some distinctions. For example, the network may send a session start only to selected eNBs. The selected eNBs may be those that are available to provide the group communication and are able to serve, e.g., within communication range, of a set of target UEs. The network may indicate the determined transmission type, e.g., either PTM or MBMS, to the selected eNBs. During session establishment, the RAN may provide a RAN capability report to the BM-SC to assist the BM-SC to determine PTM transmission mode or MBMS transmission mode in addition to take account for the UE capability. If so, session establishment may involve a three way message exchange between the BM-SC and RAN instead of a two way message exchange.

At 6, the selected eNBs join an IP multicast group. At 7, the selected eNBs provide PTM configuration information to the target UEs when the eNB decides to enable SC-PTM transmission. The content and delivery methods of the PTM configuration are described further below. At 8, the BM-SC provides one or both of GERAN radio network temporary identifier (G-RNTI) and TMGI information to the target UEs to thereby identify the UE as a member of the group call. At step 9, the UE receives the group call service by monitoring for messages that are associated with either the G-RNTI or TMGI. Further on this point, the UE uses either the G-RNTI or the TMGI depending on the bearer with which the UE is associated. The UE does not monitor for group call messages using both the G-RNTI and the TMGI.

In a second aspect of deciding between a PTM transmission type and a MBMS transmission type for group call message, the BM-SC automatically activates or establishes an MBMS bearer, while a decision of whether to use the MBMS bearer for a set of UEs is determined by one or more RAN entities, e.g., eNB, MCE or MME. In this case, the actual use of a PTM bearer or a MBMS bearer for a set of UEs is transparent to the BM-SC and GCS-AS. Depending on counting results determined by the RAN, the MCE/MME of the RAN can determine a bearer type or mixture of bearer types for different sets of UEs. For example, the RAN may determine that a first set of UEs use MBMS bearers, a second set of UEs use group bearers, and a third set of UEs use unicast bearers. MBMS transmission and associated MBMS bearers may be associated with a multi cell SFN (MC-SFN) or single cell SFN (SC-SFN) . PTM transmissions and associated group bearers may be associated with a single cell PTM (SC-PTM) or a multi cell PTM (MC-PTM) .

A UE may move between cells that support UC and may optionally support PTM and/or MBMS. In these instances, a current bearer may be disabled/deactivated, and the other bearer enabled/activated/established. In general, the decision point for MBSFN transmission is MCE and the decision point for SC-PTM is eNB. To this end, a MBMS bearer may be disabled/deactivated as follows: a MCE determines that the MBMS should be suspended and notifies relevant eNBs using existing mechanisms； the MCE indicates a suspend time to the UE to allow make-before-break switching by the UE. Relevant eNBs decide whether to setup group radio bearers. If group radio bearers are to be set up, the relevant eNBs send a PTM configuration to relevant target UEs. Alternatively, when a MBMS bearer is to be established and a group bearer is to be disabled/deactivated the MBMS bearer may be enabled/activated/established as follows: the MCE determines that a MBMS session should be started or resumed and notifies relevant eNBs using existing mechanisms. Relevant eNBs decide whether to disable/deactivate/tear down the group radio bearers being switched to MBMS bearers. When a group bearer is deactivated, the corresponding TMGI from the related PTM configuration is removed by the eNB. In this case, the eNB indicates the tear down of the group bearer to the UE to allow make-before-break switching by the UE before the group bearer is deactivated by the corresponding eNB.

A group bearer may be disabled/deactivated as follows: an eNB determines whether MBMS is activated since the eNB knows if it is within MBSFN area to transmit MBSFN. If MBMS is not activated, the eNB disables/deactivates the group bearer and removes the corresponding TMGI from the related PTM configuration. The eNB then sets up a UC bearer. If the eNB determines that an MBMS bearer is activated, the UE may switch from PTM to MBMS. A group bearer may be enabled/activated/established as follows: an eNB decides to enable PTM. The eNB activates/establishes a group bearer and adds the corresponding TMGI in the relevant PTM configuration.

FIG. 14 is a diagram 1400 illustrating another aspect forbearer selection and establishment. At 1, a TMGI is allocated for a group call by one of a BM-SC or a GCSE-AS. At 2, the BM-SC or a GCSE-AS activates/establishes an MBMS bearer for sending group communication to target UEs for which an MBMS transmission type is determined. At 3, the BM-SC initiates a session start procedure. The start procedure may be based on 3GPP TS 23.246. At 4, the BM-SC provides one or more TMGI information in USD to the target UEs over unicast channel or MBMS channel. The information is provided over unicast or broadcast to the relevant eNBs. At 5, the eNBs join an IP multicast group.

At 6, the RAN obtains information from UE reports and uses the UE information to determine between a PTM transmission or a MBMS transmission for sets of UEs. As described above, the UE information may include serving cell identifications of the UE, capabilities of the UE, and a number of UEs. The RAN may receive the information from the UEs by autonomous reporting by the UE in accordance with a SIB setting, or based on UE reporting capability. At 7, the RAN decides to use a PTM transmission, e.g., a single cell PTM, or an MBMS transmission, e.g., over a SC-SFN or MC-SFN. The decision may be made based on UE report information as described above.

At 8, the RAN may indicate to the BM-SC if PTM is enabled. At 9, the eNBs provide PTM configuration information to the target UEs. The content and delivery methods of the PTM configuration are described further below. At step 11, the UE receives the group call service by monitoring associated bearer with either the G-RNTI for PTM or TMGI for MBMS.

PTM Configuration Content and Delivery

Included in the processes described above is the provision of a PTM configuration, e.g., a SC-PTM. The SC-PTM configuration includes information that enables a target UE to receive group call communications. The content of the PTM configuration includes:

TMGI and G-RNTI mapping for each group service. The TMGI identifies the group call service, while the G-RNTI identifies the PTM bearer and is used by the UE to decode the corresponding group data over shared PDSCH.

Service availability information for neighbor cells, such as available TMGI/SAI lists, for both inter-frequency and intra-frequency cells. This information may be included in a message separate from the PTM configuration message.

TM modes (TM2 is default if not indicated) .

DRX and/or SPS configuration.

Header compression (ROHC-U) configuration if header compression is enabled.

Number of retransmissions of group call messages and the time between retransmissions.

Retransmission configuration.

Whether an idle UE will send Group NACK.

Whether a connected UE will send Group NACK.

Available PTM reception modes (e.g., idle mode, connected mode, and hybrid mode) and thresholds, including for example, a threshold to enter connected mode.

Service continuity parameters (neighbor cell’s TMGI list) .

Cross carrier scheduling configuration.

If cross carrier scheduling is enabled, an eNB can define PTM specific secondary cell (Scell) Index for Scell and configurable Scell, and async Cell in PTM configuration. Such Scell index is only applicable to PTM transmissions and PTM reception. A group call sent over unicast bearer can have a different Scell index corresponding to a unicast configuration. In this case, the PTM configuration may further include CP type and PDSCH start for Scell and configurable Scell.

If a PTM transmission can be scheduled in the same subframe with a channel state information reference signal (CSI-RS) : The eNB signals a CSI-RS configuration for each service. The service specific CSI-RS configuration may be done for the purpose of rate matching. The CSI-RS configuration may include all UEs CSI-RS configuration and zero power (ZP) CSI-RS (ZP-CSI-RS) configuration, as the eNB is not aware of which UE is interested in which group service. If the UE reports interest in a service by specifying the associated TMGI in a MBMS Interest Indication (MII) , the eNB can include the CSI-RS and ZP-CSI-RS configurations for all UEs interested in the same service. For CSI reporting, unicast CSI-RS/ZP-CSI-RS configuration applies

Additional PTM configuration information may include: DRX configuration for G-RNTI, and a semi persistent scheduling (SPS) G-RNTI configuration for each group if SPS is enabled.

For better UE battery consumption, the subframes which can be potentially scheduled for G-RNTI can be signaled to a UE. In this instance, the UE only monitors for the G-RNTI on those subframes, and monitors C-RNTI on all subframes.

The PTM configuration may be delivered in any of the following various methods including GCCH, SIB/BCCH, DCCH and MCCH. In a first method, the PTM configuration may be sent on a shared downlink control channel, e.g., PDSCH. In this case, each group call service group has its own G-RNTI. The PTM configuration is sent using TM2 on a GCCH (Group Control Channel) . The GCCH has repetition and modification period. In one aspect of sending PTM configuration over PDSCH, the PTM configuration is using the same G-RNTI as each group and G-RNTI to TMGI mapping is included in the USD. In this case, the MAC header may indicate whether a payload is for PTM configuration or for PTM user data. Alternatively, a control channel, e.g., PDCCH, may indicate whether a payload is for PTM configuration or PTM user data. In another aspect of sending PTM configuration over PDSCH, the PTM configuration may be sent on a global common G-RNTI (GS-RNTI) that is independent with each service group. In this case, the GS RNTI is common for all groups. Sub-option a: A TMGI independent G-RNTI is reserved for GCCH transmission. Sub-option b: GCCH is transmitted using TMGI specific G-RNTI. Both signalling and user data are transmitted using the G-RNTI. The UE can differentiate GCCH and TCH through LCID in MAC header. In this sub-option, the UE knows TMGI to G-RNTI mapping from USD (User service description, 3GPP TS26.346) .

In a second method of delivering a PTM configuration, the configuration is sent via common signaling through SIB. The SIB may be a new SIB or a modified existing SIB. In this case, a target UE can acquire the PTM configuration while in either of a RRC_IDLE or a RRC connected state. For carrier aggregation, the SIB can be sent on each individual carrier, or the SIB for a SCC can be sent via common signaling on PCC. In this method, the SIB cycle may be reduced, e.g., from typical 100 ms cycles down to 40ms cycles, to meet latency requirements.

In a third method of delivering PTM configuration information, the PTM configuration may be sent via dedicated RRC signaling. In this case, when the UE first communicates with GCSE-AS, e.g., when subscribing to the GCS group, the UE receives the initial PTM configuration from the eNB through RRC signaling. However, each time the PTM configuration is updated, the eNB pages the UE in order to send the updated PTM configuration to the UE. The eNB may page the UE based on the G-RNTI corresponding to the GCS group.

In a fourth method of delivering PTM configuration, the configuration is sent on the MCCH. PTM configuration signaling should be sent with high reliability. MCCH on (multi-cell) MBSFN has good channel quality, hence good reliability, due to MBSFN gain. Even if (multi-cell) MBSFN is not available e.g. due to no synchronization of MBMS signals between eNBs, MCCH can still be used for single site MBSFN, but with a lower MCS to improve reliability of receiving the transmission. Configuring SC-PTM using MCCH may reuse existing MBMS signaling mechanisms such as: MCCH configuration by SIB 13, MCCH modification period, MCCH repetition, and MCCH change notification.

To reduce the SC-PTM bearer establishment delay, the MCCH modification period and MCCH repetition period can be reduced. The SC-PTM configuration can be same (or almost same) in MBSFN area or adjacent cells. This also enables the possibility of having MBSFN like MC-PTM transmission in a subset of cells of an MBSFN area.

Below is an example of parameters of a SC-PTM configuration:

The above SC-PTM configuration may be configured by adding new parameters into existing MCCH message. For example, SC-PTM can be configured by adding new parameters into the MBSFNAreaConfiguration message.

In a first option, the SC-PTM configuration may be added to PMCH configuration message as shown below:

When sc-ptm-Config-r13 is present, the PMCH is carried over SC-PTM through the G-RNTI indicated in sc-ptm-Config-r13. The MSP (mch-SchedulingPeriod-r9) acts DRX cycle length if DRX parameters in sc-ptm-Config-r13 is not included. UE differentiates SDUs of multiple MTCH/session per the MAC PDU header.

In a second option, the SC-PTM configuration may be added to MBMS session information:

When sc-ptm-Config-r13 is present, the corresponding TMGI is carried over SC-PTM through the G-RNTI indicated in sc-ptm-Config-r13. The MSP (mch-SchedulingPeriod-r9) acts DRX cycle length if DRX parameters in sc-ptm-Config-r13 is not included. UE differentiates SDUs of multiple MTCH/session per the MAC PDU header.

Compared to eMBMS, SC-PTM enables eNB to dynamically decide MCS and PRBs based on the CQI information from interested UEs. HARQ NACK feedback may be enabled for eNB to retransmit the packet or adjust MCS of future scheduling. The dataMCS and sf-AllocationEnd are used to indicate the default MCS and PRBs allocation when a SPS like transmission is used.

In another option, a new MCCH message can be defined for SC-PTM configuration. An example message follows:

The new message may be transmitted using the MCCH modification mechanism and MCCH configuration as specified in SIB 13.

It is also possible to define a separate configuration and modification mechanism. In such case, the SC-PTM configuration channel is not the traditional MCCH, but may make use of the MBSFN to transmit the SC-PTM configuration channel. The configuration may also be delivered to UE by the combination of

option

1, 2, 4, e.g. TMGI to G-RNTI mapping in SIB and other configuration parameters in GCCH.

Synchronization

In the processes described above, GCS communications are sent to a group of UEs. In the case where group call services are provided to a first set of UEs in the group by a MBMS transmission through an MBMS bearer, and a second set of UEs in the group by a PTM transmission through a group bearer, such communications may involve synchronization. Synchronization may be done in accordance with a synchronization protocol as described in 3GPP, TS 25.446, section 12.1.0.

A synchronized (SYNC) packet data unit (PDU) may carry a group service call message in its payload. A SYNC PDU header includes a time stamp. The time stamp indicates the timing based on which the all eNBs associated with the MBMS service send MBMS data over the air at same time (in a time synchronized manner) to make a MBSFN work. The timestamp setting in a SYNC PDU adds additional delay to account for the followings: Data arrival time, Maximum Transmission Delay from the BM-SC to the farthermost eNB, Processing delay in the eNB etc.

As noted above, a SYNC protocol may be needed in cases of mixed MBMS and PTM bearers. In cases where only group bearers are present, however, a SYNC protocol can be disabled.

To this end, in a first option, in a mixed MBMS bearer and group bearer scenario, the network, e.g., BM-SC, may set the SYNC PDU header based on the following rule. eNBs providing group communication through a group bearer, referred to as PTM activated eNBs, ignore SYNC PDU headers and send SYNC PDU payload as soon as possible based on available radio resource on a downlink channel. In a second option, in a group bearer only scenario, the network, e.g., BM-SC, creates a dummy SYNC PDU header by omitting all the delays and PTM activated eNBs ignore the SYNC PDU headers and send SYNC PDU payload as soon as possible based on available radio resource.

In a third option, a PDU type is created for the group bearer only scenario. FIG. 15 is a diagram 1500 of a PDU for sending group call communication through a group bearer. The PDU includes only payload data and related fields. There are no headers with synchronization information.

Service Continuity

Disclosed below are concepts related to maintaining service continuity at a UE among unicast reception, MBMS reception, and SC-PTM reception. When UE is moving, the UE may make a decision to continue the service with MBMS, SC-PTM, or UC. Furthermore, a UE may make a decision to continue service while moving across different cells that support SC-PTM.

Such continuity decisions may be made when the UE is in idle mode or connected mode. Cell selection/reselection mechanisms enable the UE to receive the desired group service (s) in RRC idle mode, while handover procedures enable the UE to receive the desired group service (s) in RRC connected state. Signalling mechanisms allow the network to provide group service information and single cell PTM configuration in addition to MBMS information (SIB 15) . Signalling mechanisms also allow the UE to report the desired group service (s) reception in RRC Connected mode.

Idle Mode

The UE discovers the group services and associated bearer (s) when the UE perform cell selection to receive the service. The UE may receive group services through PTM or MBMS in idle mode.

Similar to eMBMS, a group service via SC-PTM may be provided via more than one frequency layer in the same geographic area. The frequencies used to provide SC-PTM service (s) may change from one cell to another within a PLMN. A UE which is receiving group service via SC-PTM can autonomously make the frequency that is providing group services the highest priority when performing cell reselection. When the group service (s) the UE is interested in are not available or the UE is no longer interested in receiving the service (s) then normal cell reselection rules can be applied. On the same frequency layer (intra-frequency) , neighboring cells may or may not support SC-PTM or MBMS transmissions. The UE should be allowed to select a desired cell for the service reception and service continuity in addition to current cell selection/reselection criteria. For example, if the UE discovers that multiple neighbor cells have sufficient signal strength (where the UE can decode unicast signal) , the UE may select a cell with SC-PTM support.

In a first option, the UE reads a neighbor cell’s SC-PTM service availability information from the neighbor cell and/or SIB 15 (for MBMS) in the serving cell before selecting a new serving cell on which to camp. This option involves increased UE complexity because the UE needs to read one or more neighbor cell’s SC-PTM service availability information before performing cell selection.

In a second option, the current serving cell sends neighbor cell’s SC-PTM service availability information (similar to how SIB 15 for MBMS is handled) and the UE switches serving cells based on neighbor cell’s SC-PTM service availability information and/or SIB 15 (for MBMS) . In a first aspect of the second option, existing USD TMGI and SAI mapping information and SIB 15 information is used by the UE to distinguish if a service of interest is available via MBMS or SC-PTM. In this aspect, there is no change to SIB 15. In a second aspect of the second option, a group service indication for each TMGI is added to the USD, and is used by the UE, along with the TMGI and SAI mapping information, to distinguish if service is available on MBMS or SC-PTM. The UE can determine if service is available on MBMS or SC-PTM on neighbor cells/frequencies. No changes are needed to SIB 15. In a third aspect of the third option, an available TMGI list is added to SIB 15 or is provided in a new SIB. The available TMGI list may indicate which SAI is available over SC-PTM and/or eMBMS. Alternatively, the available TMGI list may only include SC-PTM TMGI list. FIG. 16 is an illustration 1600 of a system, information block 15 (SIB 15) information element that includes a TMGI list element. In a fourth aspect of the second option, SAI sent from USD may only include a single cell identified by ECGI or alternatively the USD can include TMGI and ECGI mapping. The serving cell either broadcasts an available TMGI on neighbor cells or broadcasts neighbor cell ECGI (s) in SIB 15 or in a new SIB to assist the UE in selecting a proper cell for receiving the group service.

In a third option, a UE determines if it is located in the cell edge region of the current cell. Such determination can be based on RSRP/RSRQ/PTM service quality/BLER. IF the UE us at the cell edge, the UE switches to RRC_CONNECTED state and applies an existing handover mechanism in RRC_CONNTECTED state to avoid service interruption.

In a fourth option, a UE determines that it is in cell edge of current cell. Such determination can be based on RSRP/RSRQ/PTM service quality/BLER. If the UE is at the cell edge, the UE initiates a connectionless access procedure, e.g., PRACH. To this end, the UE sends Cell Change Request (which may include TMGI of interest, and signal strength measurements) to eNB, and the eNB decides target cells per UE interested TMGI and measurement results. The eNB sends Cell Change Response (which may include target cell, SIBs, MCCH/GCCH container) to UE. The UE reselects to the eNB indicated target cell and quick resume service on MBMS bearer or PTM bearer.

FIG. 17 is a diagram 1700 illustrating service continuity for a UE in idle mode. At 1, the UE reads system information for cell reselection parameters and neighbor list from the current serving cell/eNB. At 2, the UE initiates a random access procedure with the eNB based on measurement results. At 3, the eNB responds to the random access procedure and assigns UL resource to the UE. At 4, the UE sends a Cell Change Request including TMGI associated with a service of interest and optional measurement results. At 5, the eNB determines target cells based on TMGI and measurement results. If measurement results are not available, the eNB will specify a list of target cells based on configuration information of neighboring cells. The eNB sends a Cell Change Response (target cells, SIBs, MCCH/GCCH container) to the UE. If no suitable cell supports PTM or MBMS, the eNB also indicates that there is no suitable cell to the UE so that the UE can establish a UC connection based on current procedures. At 6, the UE reselects to one of the indicated target cells if none correspond to the serving cell and quickly resumes service based on SIBs and the PTM configuration or MBSFN area configuration received in the MCCH/GCCH container.

Connected Mode

The UE may receive group services via PTM or MBMS bearer when the UE is in RRC connected state. The UE sends assistant information to an eNB for eNB to try to ensure group service continuity. The UE may report assistance information to the eNB in the form of an MBMS interest indication (MII) message. This MII message may include TMGI associated with a service of interest (or G-RNTI associated with the service) . If the UE reports multiple frequencies or multiple TMGIs associated with different frequencies, it is implied that the UE can receive them simultaneously. The UE may also report assistance information to the eNB in the form of a group service priority in addition to current priority for MBMS and unicast service. This assistance information is used by eNB in overload situation to determine which service (group service, regular MBMS service, or unicast) to drop.

Based on the assistance information, the eNB may handover the UE to the frequency or cell with PTM support or MBMS support. The eNB may obtain each neighbor cell PTM configuration via X2. In the handover command, the eNB may send the neighbor cell PMT configuration to the UE. If neither PTM nor MBMS is supported by target eNBs, the eNB handovers the UE to UC or indicates to the UE to setup a unicast channel on the current cell and follow UC handover procedures. To make make-before-break work, the UE should notify the application server that a unicast connection has been established before SC-PTM is dropped by the application server.

For carrier aggregation/dual connectivity, the UE may receive the group service on SCell/SeNB, configurable SCell, or even asynced SCell. The UE should be able to get neighbor cell SC-PTM service availability information in the PCell and then tunes to the corresponding cell without changing PCell.

FIG. 18 is a flow chart of a method 1800 of group call service communication. The method may be performed by an eNB and/or a network entity. At 1802, the eNB and/or a network entity determines a transmission type or mode for sending a group call message of a group call service to a set of UEs based on information received from the set of UEs. The transmission type may be one of UC transmission type, a PTM transmission type, e.g., a single cell point-to-multipoint (SC-PTM) or a multicell point-to-multipoint (MC-PTM) , and a MBMS transmission type, e.g., a single site MBMS transmission or a multisite MBMS transmission. The eNB and/or a network entity may determine a transmission type by determining at least one of serving cell identifications of UEs in the set of UEs, capabilities of UEs in the set of UEs, and a number of UEs in the set of UEs, based on the information received from the set of UEs. In one configuration, at 1808 a network entity or GCS-AS receives the information from the set of UEs. The network entity may be a broadcast network entity, e.g., BS-MC, or a RAN entity, e.g. eNB, MME, MCE.

At 1804, the eNB and/or a network entity establishes at least one of a UC bearer, a group bearer or a MBMS bearer for the set of UEs based on the determination using known techniques. At 1806, the eNB and/or a network entity sends the group call message through the at least one established bearer to the set of UEs. As part of sending the group call message in the case of a PTM transmission type, the eNB and/or network entity provides a PTM configuration to the set of UEs. Furthermore, as part of sending the group call message, and in the case of a broadcast network entity determining the transmission type, the broadcast network entity may start a call session with one or more selected eNBs and indicate the transmission type to the one or more selected eNBs.

At 1810, the eNB and/or network entity maintains group call service continuity with a UE in the set of UEs based on movement information received from the UE. To this end, the eNB and/or network entity may receive an indication from the UE that the UE is moved out of an area covered by a PTM transmission and into an area covered by a UC transmission； and in response thereto deactivate the group bearer for the UE； establish a UC bearer for the UE； and send the group call message through the UC bearer. The eNB and/or network entity may thereafter receive an indication from the UE that the UE is moved into an area covered by one of a PTM transmission or an MBMS transmission； and in response thereto establish a corresponding one of a group bearer or a MBMS bearer； deactivate the UC bearer； and send the group call message through the corresponding one of a group bearer or a MBMS bearer.

FIG. 19 is a conceptual data flow diagram 1900 illustrating the data flow between different modules/means/components in an exemplary apparatus 1902 configured to implement the method of FIG. 18. The apparatus 1902 may be an eNB and/or a network entity. The apparatus 1902 includes a receiving module 1910, a transmission type module 1912, a bearer establishment module 1914, a transmission module 1916, and a service continuity module 1918.

The transmission type module 1912 is configured to determine a transmission type for sending a group call message of a group call service to a set of

UEs

1940, 1942 based on information received from the set of UEs. The information is received from the

UEs

1940, 1942 through the receiving module 1910. The bearer establishment module 1914 is configured to establish at least one of a UC bearer, a group bearer or a MBMS bearer for the set of UEs based on the determination outcome of the transmission type module 1912. The transmission module 1916 is configured to send the group call message through the at least one established bearer to the set of

UEs

1940, 1942. The service continuity module 1918 is configured to maintain group call service continuity with a UE in the set of UEs based on movement information received from the UE.

The apparatus 1902 may include additional modules that perform each of the blocks of the algorithm in the aforementioned flow chart of FIG. 18. As such, each block in the aforementioned flow charts of FIG. 18 may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 20 is a diagram 2000 illustrating an example of a hardware implementation for an apparatus 1902' employing a processing system 2014 configured to implement the method of FIG. 18. The processing system 2014 may be implemented with a bus architecture, represented generally by the bus 2024. The bus 2024 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 2014 and the overall design constraints. The bus 2024 links together various circuits including one or more processors and/or hardware modules, represented by the processor 2004, the

modules

1910, 1912, 1914, 1916, 1918, and the computer-readable medium /memory 2006. The bus 2024 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 2014 may be coupled to a transceiver 2010. The transceiver 2010 is coupled to one or more antennas 2020. The transceiver 2010 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 2010 receives a signal from the one or more antennas 2020, extracts information from the received signal, and provides the extracted information to the processing system 2014, specifically the receiving module 1910. In addition, the transceiver 2010 receives information from the processing system 2014, specifically the transmission module 1916, and based on the received information, generates a signal to be applied to the one or more antennas 2020. The processing system 2014 includes a processor 2004 coupled to a computer-readable medium /memory 2006. The processor 2004 is responsible for general processing, including the execution of software stored on the computer-readable medium /memory 2006. The software, when executed by the processor 2004, causes the processing system 2014 to perform the various functions described supra for any particular apparatus. The computer-readable medium /memory 2006 may also be used for storing data that is manipulated by the processor 2004 when executing software. The processing system further includes at least one of the

modules

1910, 1912, 1914, 1916, 1918. The modules may be software modules running in the processor 2004, resident/stored in the computer readable medium / memory 2006, one or more hardware modules coupled to the processor 2004, or some combination thereof.

In one configuration, the apparatus 1902/1902' for wireless communication includes means for determining a transmission type for sending a group call message of a group call service to a set of UEs based on information received from the set of UEs, the transmission type being one of a unicast (UC) transmission type, a point-to-multipoint (PTM) transmission type, and a multimedia broadcast service (MBMS) transmission type； means for establishing at least one of one of a UC bearer, a group bearer or a MBMS bearer for the set of UEs based on the determination； means for sending the group call message through the at least one established bearer to the set of UEs； and means for maintains group call service continuity with a UE in the set of UEs based on movement information received from the UE. The aforementioned means may be one or more of the aforementioned modules of the apparatus 1902 and/or the processing system 2014 of the apparatus 1902' configured to perform the functions recited by the aforementioned means.

FIG. 21 is a flow chart 2100 of a method of maintaining continuity of a group call service by a UE camped on a current cell in an idle mode, wherein the current cell provides the group call service by PTM broadcast. The method may be performed by a UE. At 2102, the UE obtains service availability information for a neighboring cell. The service availability information for the neighboring cell may be obtained from the neighbor cell, or from the current cell. The service availability information may include a TMGI and SAI mapping, and may further include a group service indication for each TMGI. The service availability information may include transmission type availabilities for each TMGI.

At 2104, the UE determines whether the service availability information indicates that the neighbor cell provides the group call service by PTM broadcast. At 2106, the UE switches to the neighbor cell when the neighbor cell provides the group call service by PTM broadcast.

FIG. 22 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus 2202 configured to implement the method of FIG. 21. The apparatus 2202 may be a UE. The apparatus 2202 includes a receiving module 2210, an obtaining module 2212, a determining module 2214 and a switching module.

The obtaining module 2212 is configured to obtain service availability information for a neighboring cell 2242. The service availability information may be obtained from the receiving module 2210 that is configured to receive signals with the information that are transmitted by the neighboring cell 2242. The determining module 2214 is configured to determine whether the service availability information indicates that the neighbor cell 2242 provides the group call service by PTM broadcast. The switching module 2216 is configured to switch to the neighbor cell 2242 when the neighbor cell provides the group call service by PTM broadcast.

The apparatus 2202 may include additional modules that perform each of the blocks of the algorithm in the aforementioned flow chart of FIG. 21. As such, each block in the aforementioned flow charts of FIG. 21 may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 23 is a diagram illustrating an example of a hardware implementation for an apparatus 2202' employing a processing system 2314 configured to implement the method of FIG. 21. The processing system 2314 may be implemented with a bus architecture, represented generally by the bus 2324. The bus 2324 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 2314 and the overall design constraints. The bus 2324 links together various circuits including one or more processors and/or hardware modules, represented by the processor 2304, the

modules

2210, 2212, 2214, 2216, and the computer-readable medium /memory 2306. The bus 2324 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 2314 may be coupled to a transceiver 2310. The transceiver 2310 is coupled to one or more antennas 2320. The transceiver 2310 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 2310 receives a signal from the one or more antennas 2320, extracts information from the received signal, and provides the extracted information to the processing system 2314, specifically the receiving module 2210. In addition, the transceiver 2310 receives information from the processing system 2314, and based on the received information, generates a signal to be applied to the one or more antennas 2320. The processing system 2314 includes a processor 2304 coupled to a computer-readable medium /memory 2306. The processor 2304 is responsible for general processing, including the execution of software stored on the computer-readable medium /memory 2306. The software, when executed by the processor 2304, causes the processing system 2314 to perform the various functions described supra for any particular apparatus. The computer-readable medium /memory 2306 may also be used for storing data that is manipulated by the processor 2304 when executing software. The processing system further includes at least one of the

modules

2210, 2212, 2214, 2216. The modules may be software modules running in the processor 2304, resident/stored in the computer readable medium /memory 2306, one or more hardware modules coupled to the processor 2304, or some combination thereof.

In one configuration, the apparatus 2202/2202' for wireless communication includes means for obtaining service availability information for a neighboring cell ； means for determining whether the service availability information indicates that the neighbor cell provides the group call service by PTM broadcast； and means for switching to the neighbor cell when the neighbor cell provides the group call service by PTM broadcast. The aforementioned means may be one or more of the aforementioned modules of the apparatus 2202 and/or the processing system 2314 of the apparatus 2202' configured to perform the functions recited by the aforementioned means.

FIG. 24 is a flow chart 2400 of a method of maintaining continuity of a group call service by a UE camped on a current cell in an idle mode, the current cell providing the group call service by PTM broadcast. At 2402, the UE determines a need for a cell change based on a metric of service quality of the UE relative to the current cell. The metric of service is based on one or more of RSRP, RSRQ, PTM service quality, and BLER. At 2404, the UE initiates a random access procedure with the current cell. At 2406, the UE sends a group call service identifier corresponding to the group call service, and neighbor cell measurement results to the current cell. At 2408, the UE receives a target cell indication from the current cell, the target cell providing the group call service by PTM broadcast. At 2410, the UE reselects to the target cell.

FIG. 25 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus 2502 configured to implement the method of FIG. 24. The apparatus 2502 may be a UE. The apparatus 2502 includes a receiving module 2510, a cell change determining module 2512, a RACH module 2514, a transmission module 2516, and a cell reselection module 2518.

The cell change determining module 2512 is configured to determine a need for a cell change based on a metric of service quality of the UE relative to a current cell 2542. The RACH module 2514 is configured to initiate a random access procedure with the current cell 2542. The transmission module 2516 is configured to sends a group call service identifier corresponding to the group call service, and neighbor cell measurement results to the current cell 2542. The receiving module 2510 is configured to receive a target cell 2540 indication from the current cell 2542. The target cell 2540 provides the group call service by PTM broadcast. The cell reselection module 2518 is configured to reselect to the target cell 2540.

The apparatus 2502 may include additional modules that perform each of the blocks of the algorithm in the aforementioned flow chart of FIG. 24. As such, each block in the aforementioned flow charts of FIG. 24 may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 26 is a diagram illustrating an example of a hardware implementation for an apparatus 2502' employing a processing system 2614 configured to implement the method of FIG. 21. The processing system 2614 may be implemented with a bus architecture, represented generally by the bus 2624. The bus 2624 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 2614 and the overall design constraints. The bus 2624 links together various circuits including one or more processors and/or hardware modules, represented by the processor 2604, the

modules

2510, 2512, 2514, 2516, 2518 and the computer-readable medium /memory 2606. The bus 2624 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 2614 may be coupled to a transceiver 2610. The transceiver 2610 is coupled to one or more antennas 2620. The transceiver 2610 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 2610 receives a signal from the one or more antennas 2620, extracts information from the received signal, and provides the extracted information to the processing system 2614, specifically the receiving module 2510. In addition, the transceiver 2610 receives information from the processing system 2614, and based on the received information, generates a signal to be applied to the one or more antennas 2620. The processing system 2614 includes a processor 2604 coupled to a computer-readable medium /memory 2606. The processor 2604 is responsible for general processing, including the execution of software stored on the computer-readable medium /memory 2606. The software, when executed by the processor 2604, causes the processing system 2614 to perform the various functions described supra for any particular apparatus. The computer-readable medium /memory 2606 may also be used for storing data that is manipulated by the processor 2604 when executing software. The processing system further includes at least one of the

modules

2510, 2512, 2514, 2516, 2518. The modules may be software modules running in the processor 2604, resident/stored in the computer readable medium /memory 2606, one or more hardware modules coupled to the processor 2604, or some combination thereof.

In one configuration, the apparatus 2502/2502' for wireless communication includes means for determining a need for a cell change based on a metric of service quality of the UE relative to a current cell； means initiating a random access procedure with the current cell； means for sending a group call service identifier corresponding to the group call service, and neighbor cell measurement results to the current cell； means for receiving a target cell indication from the current cell 2542, wherein the target cell provides the group call service by PTM broadcast； and means for reselecting to the target cell. The aforementioned means may be one or more of the aforementioned modules of the apparatus 2502 and/or the processing system 2614 of the apparatus 2502' configured to perform the functions recited by the aforementioned means.

FIG. 27 is a flow chart 2700 of a method of maintaining continuity of a group call service by a UE camped on a current cell in a connected mode, the current cell providing the group call service to the UE by one of PTM broadcast or MBMS broadcast. The method may be performed by a network entity. At 2702 the network entity receives information indicating the group call service. At 2704, the network entity determines whether any one of a plurality of neighbor cells supports either of PTM broadcast or MBMS broadcast of the group call service. At 2706, the network entity sends a handover command to the UE when one of the plurality of neighbor cells support PTM broadcast, the handover command indicating the supporting neighbor cell and including PTM configuration information.

FIG. 28 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus 2802 configured to implement the method of FIG. 27. The apparatus 2802 may be an eNB and/or a network entity. The apparatus 2802 includes a receiving module 2810, a neighbor cell determining module 2812, a handover module 2814, and a transmission module 2816.

The receiving module 2810 is configured to receive information indicating the group call service. The neighbor cell determining module 2812 is configured to determine whether any one of a plurality of neighbor cells supports either of PTM broadcast or MBMS broadcast of the group call service. The handover module 2814 is configured to provide a handover command to the UE 2840 when one of the plurality of neighbor cells support PTM broadcast. The handover command indicates the supporting neighbor cell and including PTM configuration information. The transmission module 2816 is configured to send the handover command to the UE 2840.

The apparatus 2802 may include additional modules that perform each of the blocks of the algorithm in the aforementioned flow chart of FIG. 27. As such, each block in the aforementioned flow chart of FIG. 27 may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 29 is a diagram illustrating an example of a hardware implementation for an apparatus 2802' employing a processing system 2914 configured to implement the method of FIG. 27. The processing system 2914 may be implemented with a bus architecture, represented generally by the bus 2924. The bus 2924 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 2914 and the overall design constraints. The bus 2924 links together various circuits including one or more processors and/or hardware modules, represented by the processor 2904, the

modules

2810, 2812, 2814, 2816, and the computer-readable medium /memory 2906. The bus 2924 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 2914 may be coupled to a transceiver 2910. The transceiver 2910 is coupled to one or more antennas 2920. The transceiver 2910 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 2910 receives a signal from the one or more antennas 2920, extracts information from the received signal, and provides the extracted information to the processing system 2914, specifically the receiving module 2810. In addition, the transceiver 2910 receives information from the processing system 2914, specifically the transmission module 2816, and based on the received information, generates a signal to be applied to the one or more antennas 2920. The processing system 2914 includes a processor 2904 coupled to a computer-readable medium /memory 2906. The processor 2904 is responsible for general processing, including the execution of software stored on the computer-readable medium /memory 2906. The software, when executed by the processor 2904, causes the processing system 2914 to perform the various functions described supra for any particular apparatus. The computer-readable medium /memory 2906 may also be used for storing data that is manipulated by the processor 2904 when executing software. The processing system further includes at least one of the

modules

2810, 2812, 2814, 2816. The modules may be software modules running in the processor 2904, resident/stored in the computer readable medium /memory 2906, one or more hardware modules coupled to the processor 2904, or some combination thereof.

In one configuration, the apparatus 2802/2802' for wireless communication includes means for receiving information indicating the group call service； means for determining whether any one of a plurality of neighbor cells supports either of PTM broadcast or MBMS broadcast of the group call service； means for providing a handover command to the UE when one of the plurality of neighbor cells support PTM broadcast, wherein the handover command indicates the supporting neighbor cell and including PTM configuration information； and means for sending the handover command to the UE 2840. The aforementioned means may be one or more of the aforementioned modules of the apparatus 2802 and/or the processing system 2914 of the apparatus 2802' configured to perform the functions recited by the aforementioned means.

Bearer Type Selection from Network

The network may decide to enable (or to disable) SC-PTM transmission, eMBMS transmission, or both on the same or different geographic areas for a group service. The decision entity can be App server, the BM-SC, or RAN (MCE/MME) or combination of them. For example, App server may decide to send group user data to P-GW (for unicast delivery) , and/or BM-SC (for eMBMS or SC-PTM delivery) . The BM-SC then decides if to use eMBMS or SC-PTM transmission. When network decides to enable (or to disable) SC-PTM and/or eMBMS transmission, the network may need to take into account the following: (1) The UE capability to support eMBMS, SC-PTM, or both. The UE capability can be known through pre-configuration or reporting from the UE； (2) The RAN capability to support eMBMS, SC-PTM, or both. The RAN capability can be known through pre-configuration or reporting from RAN before SC-PTM/MBMS session establishment； (3) The number of the UEs that are interested in the service and their location distribution within the geographic area. The counting can be performed in App Server, BM-SC, or RAN, or the combination of them； (4) Whether eNBs within the geographic area can be time synchronized or not； and (5) The network loading and congestion status.

Service Continuity

If SC-PTM is supported in E-TUTRAN, the UE may receive a group service via unicast, eMBMS, and/or SC-PTM. The UE may receive SC-PTM or eMBMS in both RRC Idle state and RRC Connected state.

UE in RRC Idle State:

The UE may need to discover the group services and associated bearer (s) (eMBMS, or SC-PTM bearer) when the UE performs cell selection or cell reselection to receive the service. It also includes service continuity when the UE is receiving the group service in RRC Idle State. Similar as eMBMS, a group service via SC-PTM reception can be provided via more than one frequency layer in the same geographic area. The frequencies used to provide SC-PTM service (s) may change from one cell to another within a PLMN. The UE which is receiving group service via SC-PTM can autonomously make the frequency providing group services the highest priority when performing cell reselection. When the group service (s) the UE is interested in are not available or the UE is no longer interested in receiving the service (s) then normal cell reselection rules apply. On the same frequency layer, neighbouring cells may or may not support SC-PTM or eMBMS transmissions. Accordingly, the UE may be able to select a desired cell for the service reception and service continuity in addition to current cell selection/reselection criterions. There could be a few options to ensure the service continuity once the UE is receiving the group service in RRC Idle state:

Option 1: The serving cell and service layer information may send neighbour cell’s SC-PTM service availability information to avoid UE to read neighbour cell’s SC-PTM service availability information before switching over. If both eMBMS and SC-PTM for the corresponding group service is available on the neighbour cells, it can be up to UE implementation to select one or the other. If there is no neighbour cell supports SC-PTM and/or eMBMS, the UE may choose to enter RRC_CONNECTED state to follow service continuity described in UE in RRC Connected State to avoid service interruption.

Option 2: The UE determines that the UE is at the edge of SC-PTM coverage by monitoring RSRP/RSRQ or monitoring group service quality, for example, if RSRP/RSRQ is lower than a preconfigured or eNB indicated threshold, or if BLER is higher than a target value. If so, the UE then switches to the RRC Connected state to apply mechanism in RRC_CONNECTED state service continuity described in UE in RRC Connected State to avoid service interruption. This option can be further optimized without UE entering the full RRC Connected state. For example, the UE can use RACH procedures to send a Cell Change Request to eNB. The eNB decides the target cell per UE interested TMGI and measurement results. The eNB then sends Cell Change Response including the target cell and necessary configuration information to the UE. The UE can enter RRC Idle state and reselect the target cell indicated by eNB and quickly resume service on an MBMS bearer or an SC-PTM bearer.

UE in RRC Connected State:

When the UE receives the group service in RRC Connected State, the UE should be able to send assistant information to the eNB for the eNB to try to ensure group service continuity. The eNB may have the best knowledge on whether neighbour cells support SC-PTM or eMBMS through a pre-configuration or through an X2 interface. The following can be considered for SC-PTM service continuity in addition to current MBMS service continuity: (1) The UE indicates its interested group service (for example, TMGI, or group ID/G-RNTI) to the eNB in an MBMS Interested Indication message (or a new message) ； (2) The UE indicates the SC-PTM priority in addition to current priority for MBMS and unicast service. This parameter can be used by eNB in overload situation to decide which service (Group service, MBMS service, or uncast) to drop； (3) The eNB hands over the UE to the frequency or cell with PTM support or MBMS support. It is up to eNB implementation to decide which cell to handover. The eNB may obtain neighbor cell PTM configuration via an X2 interface and send the neighbor cell PTM configuration to the UE via a handover command； (4) If none of PTM or MBMS are supported from target eNBs, the eNB may indicate the UE to setup a unicast channel on the current cell and then follow UC handover procedures. To ensure make-before-break, the UE needs to notify the App server to deliver the group user data to P-GW before the eNB tears down the SC-PTM bearer； and (5) For carrier aggregation/dual connectivity, the UE may receive the group service on SCell/SeNB, Configurable SCell, or even asynced SCell. The UE should be able to get neighbour cell SC-PTM service availability information in the PCell and then tunes to the corresponding cell without changing PCell.

It is understood that the specific order or hierarchy of blocks in the processes /flow charts disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes /flow charts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C, ” “at least one of A, B, and C, ” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C, ” “at least one of A, B, and C, ” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ”

WHAT IS CLAIMED IS:

Claims

A method of group call service communication, comprising:

determining a transmission type for sending a group call message of a group call service to a set of UEs based on information received from the set of UEs, the transmission type being one of a unicast (UC) transmission type, a point-to-multipoint (PTM) transmission type, and a multimedia broadcast service (MBMS) transmission type；

establishing at least one of one of a UC bearer, a group bearer or a MBMS bearer for the set of UEs based on the determination； and

sending the group call message through the at least one established bearer to the set of UEs.
The method of claim 1, wherein determining a transmission type comprises determining at least one of serving cell identifications of UEs in the set of UEs, capabilities of UEs in the set of UEs, and a number of UEs in the set of UEs, based on the information received from the set of UEs.
The method of claim 1, wherein the PTM transmission type comprises one of a single cell point-to-multipoint (SC-PTM) or a multicell point-to-multipoint (MC-PTM) .
The method of claim 1, wherein the MBMS transmission type comprises one of a single site MBMS transmission or a multisite MBMS transmission.
The method of claim 1, further comprising:

receiving the information from the set of UEs at one of a network entity or a group call service application server (GCS-AS) ； and

sending the group call message comprises, when a PTM transmission type is determined, providing a PTM configuration to the set of UEs.
The method of claim 5, wherein the network entity comprises a broadcast network entity.
The method of claim 6, sending the group call message comprises starting a call session with one or more selected eNBs and indicating the transmission type to the one or more selected eNBs.
The method of claim 5, wherein the network entity comprises a radio access network entity.
The method of claim 1, further comprising maintaining continuity of the group call service with a UE in the set of UEs based on movement information received from the UE.
The method of claim 9, wherein maintaining continuity of group call service comprises:

receiving an indication from a UE that the UE is moved out of an area covered by the PTM transmission and into an area covered by a UC transmission；

deactivating the group bearer for the UE；

establishing a UC bearer for the UE； and

sending the group call message through the UC bearer.
The method of claim 9, wherein maintaining continuity of group call service further comprises:

receiving an indication from a UE that the UE is moved into an area covered by one of a PTM transmission or an MBMS transmission；

establishing a corresponding one of a group bearer or a MBMS bearer；

deactivating the UC bearer； and

sending the group call message through the corresponding one of a group bearer or a MBMS bearer.
The method of claim 5, wherein the PTM configuration comprises one or more of:mapping information that maps the group call service to a group identifier, group call service availability information for neighbor cells, a transmission mode, secondary cell information, retransmission and acknowledgement information, CSI-RS configuration, DRX configuration, and SPS G-RNTI configuration.
The method of claim 12, wherein the group call service is identified by a temporary mobile group identity (TMGI) and the group identifier comprises a group-radio network temporary identifier (G-RNTI) .
The method of claim 12, wherein providing a PTM configuration to the set of UEs comprises one of: sending the PTM configuration on a physical downlink shared channel, sending the PTM configuration by a common signal, sending the PTM configuration by a dedicated signal, and sending the PTM configuration on a multicast control channel (MCCH) .
The method of claim 1, wherein sending the group call message through the established bearer comprises:

when both a PTM transmission type and a MBMS transmission type are determined, sending the group call message from a first network entity to a second network entity in a packet data unit (PDU) with synchronization information； and

when only a PTM transmission type is determined, sending the group call message from the first network entity to the second network entity in a PDU without synchronization information.
The method of claim 15, wherein the PDU is structured in accordance with a synchronization protocol modified to include a dummy header.
The method of claim 15, wherein the PDU is structured to only include payload data.
The method of claim 15, wherein the second network entity comprises an eNB configured for PTM transmission of the group call message to the set of UEs, and further comprising:

in the case of a PDU with synchronization information, ignoring the synchronization information when sending the group call message to the UEs.
An apparatus for group call service communication, comprising:

means for determining a transmission type for sending a group call message of a group call service to a set of UEs based on information received from the set of UEs, the transmission type being one of a unicast (UC) transmission type, a point-to-multipoint (PTM) transmission type, and a multimedia broadcast service (MBMS) transmission type；

means for establishing at least one of one of a UC bearer, a group bearer or a MBMS bearer for the set of UEs based on the determination； and

means for sending the group call message through the at least one established bearer to the set of UEs.
The apparatus of claim 19, wherein the means for determining a transmission type is configured to determine at least one of serving cell identifications of UEs in the set of UEs, capabilities of UEs in the set of UEs, and a number of UEs in the set of UEs, based on the information received from the set of UEs.
The apparatus of claim 19, wherein the PTM transmission type comprises one of a single cell point-to-multipoint (SC-PTM) or a multi cell point-to-multipoint (MC-PTM) .
The apparatus of claim 19, wherein the MBMS transmission type comprises one of a single site MBMS transmission or a multisite MBMS transmission.
The apparatus of claim 19, further comprising:

means for means for receiving the information from the set of UEs at one of a network entity or a group call service application server (GCS-AS) ； and

wherein the means for sending the group call message is configured to provide a PTM configuration to the set of UEs when a PTM transmission type is determined.
The apparatus of claim 23, wherein the network entity comprises a broadcast network entity.
The apparatus of claim 24, the means for sending a group call message is configured to start a call session with one or more selected eNBs and indicate the transmission type to the one or more selected eNBs.
The apparatus of claim 23, wherein the network entity comprises a radio access network entity.
The apparatus of claim 19, further comprising means for maintaining continuity of the group call service with a UE in the set of UEs based on movement information received from the UE.
The apparatus of claim 27, wherein the means for maintaining continuity of group call service is configured to:

receive an indication from a UE that the UE is moved out of an area covered by the PTM transmission and into an area covered by a UC transmission；

deactivate the group bearer for the UE；

establish a UC bearer for the UE； and

send the group call message through the UC bearer.
The apparatus of claim 27, wherein the means for maintaining continuity of group call service is further configured to:

receive an indication from a UE that the UE is moved into an area covered by one of a PTM transmission or an MBMS transmission；

establish a corresponding one of a group bearer or a MBMS bearer；

deactivate the UC bearer； and

send the group call message through the corresponding one of a group bearer or a MBMS bearer.
The apparatus of claim 23, wherein the PTM configuration comprises one or more of: mapping information that maps the group call service to a group identifier, group call service availability information for neighbor cells, a transmission mode, secondary cell information, retransmission and acknowledgement information, CSI-RS configuration, DRX configuration, and SPS G-RNTI configuration.
The apparatus of claim 30, wherein the group call service is identified by a temporary mobile group identity (TMGI) and the group identifier comprises a group-radio network temporary identifier (G-RNTI) .
The apparatus of claim 30, wherein the means for sending is configured to provide a PTM configuration to the set of UEs by being further configured to: send the PTM configuration on a physical downlink shared channel, send the PTM configuration by a common signal, send the PTM configuration by a dedicated signal, or send the PTM configuration on a multicast control channel (MCCH) .
The apparatus of claim 19, wherein the means for sending the group call message through the established bearer is configured to:

send the group call message from a first network entity to a second network entity in a packet data unit (PDU) with synchronization information when both a PTM transmission type and a MBMS transmission type are determined； and

send the group call message from the first network entity to the second network entity in a PDU without synchronization information when only a PTM transmission type is determined.
The apparatus of claim 33, wherein the PDU is structured in accordance with a synchronization protocol modified to include a dummy header.
The apparatus of claim 33, wherein the PDU is structured to only include payload data.
The apparatus of claim 33, wherein the second network entity comprises an eNB configured for PTM transmission of the group call message to the set of UEs, and the means for sending is configured to:

ignore the synchronization information when sending the group call message to the UEs in the case of a PDU with synchronization information.
An apparatus for group call service communication, comprising:

a memory； and

at least one processor coupled to the memory and configured to:

determine a transmission type for sending a group call message of a group call service to a set of UEs based on information received from the set of UEs, the transmission type being one of a unicast (UC) transmission type, a point-to-multipoint (PTM) transmission type, and a multimedia broadcast service (MBMS) transmission type；

establish at least one of one of a UC bearer, a group bearer or a MBMS bearer for the set of UEs based on the determination； and

send the group call message through the at least one established bearer to the set of UEs.
A computer-readable medium storing computer executable code for group call service communication, comprising code for:

determining a transmission type for sending a group call message of a group call service to a set of UEs based on information received from the set of UEs, the transmission type being one of a unicast (UC) transmission type, a point-to-multipoint (PTM) transmission type, and a multimedia broadcast service (MBMS) transmission type；

establishing at least one of one of a UC bearer, a group bearer or a MBMS bearer for the set of UEs based on the determination； and

sending the group call message through the at least one established bearer to the set of UEs.
A method of maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in an idle mode, the current cell providing the group call service by point-to-multipoint (PTM) broadcast, said method comprising:

obtaining service availability information for a neighboring cell；

determining whether the service availability information indicates that the neighbor cell provides the group call service by PTM broadcast； and

switching to the neighbor cell when the neighbor cell provides the group call service by PTM broadcast.
The method of claim 39, wherein the service availability information for the neighboring cell is obtained from the neighbor cell.
The method of claim 39, wherein the service availability information for the neighbor cell is obtained from the current cell.
The method of claim 41, wherein the service availability information comprises a TMGI and SAI mapping.
The method of claim 42, wherein the service availability information further comprises a group service indication for each TMGI.
The method of claim 41, wherein the service availability information comprises transmission type availabilities for each TMGI.
An apparatus for maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in an idle mode, the current cell providing the group call service by point-to-multipoint (PTM) broadcast, said apparatus comprising:

means for obtaining service availability information for a neighboring cell；

means for determining whether the service availability information indicates that the neighbor cell provides the group call service by PTM broadcast； and

means for switching to the neighbor cell when the neighbor cell provides the group call service by PTM broadcast.
An apparatus for maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in an idle mode, the current cell providing the group call service by point-to-multipoint (PTM) broadcast, said apparatus comprising:

a memory； and

at least one processor coupled to the memory and configured to:

obtain service availability information for a neighboring cell；

determine whether the service availability information indicates that the neighbor cell provides the group call service by PTM broadcast； and

switch to the neighbor cell when the neighbor cell provides the group call service by PTM broadcast.
A computer-readable medium storing computer executable code for maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in an idle mode, the current cell providing the group call service by point-to-multipoint (PTM) broadcast, comprising code for:

obtaining service availability information for a neighboring cell；

determining whether the service availability information indicates that the neighbor cell provides the group call service by PTM broadcast； and

switching to the neighbor cell when the neighbor cell provides the group call service by PTM broadcast.
A method of maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in an idle mode, the current cell providing the group call service by point-to-multipoint (PTM) broadcast, said method comprising:

determining a need for a cell change based on a metric of service quality of the UE relative to the current cell；

initiating a random access procedure with the current cell；

sending a group call service identifier corresponding to the group call service, and neighbor cell measurement results to the current cell；

receiving a target cell indication from the current cell, the target cell providing the group call service by PTM broadcast； and

reselecting to the target cell.
The method of claim 48, wherein the metric of service is based on one or more of RSRP, RSRQ, PTM service quality, and BLER.
An apparatus for maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in an idle mode, the current cell providing the group call service by point-to-multipoint (PTM) broadcast, said apparatus comprising:

means for determining a need for a cell change based on a metric of service quality of the UE relative to the current cell；

means for initiating a random access procedure with the current cell；

means for sending a group call service identifier corresponding to the group call service, and neighbor cell measurement results to the current cell；

means for receiving a target cell indication from the current cell, the target cell providing the group call service by PTM broadcast； and

means for reselecting to the target cell.
An apparatus for maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in an idle mode, the current cell providing the group call service by point-to-multipoint (PTM) broadcast, said apparatus comprising:

a memory； and

at least one processor coupled to the memory and configured to:

determine a need for a cell change based on a metric of service quality of the UE relative to the current cell；

initiate a random access procedure with the current cell；

send a group call service identifier corresponding to the group call service, and neighbor cell measurement results to the current cell；

receive a target cell indication from the current cell, the target cell providing the group call service by PTM broadcast； and

reselect to the target cell.
A computer-readable medium storing computer executable code for maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in an idle mode, the current cell providing the group call service by point-to-multipoint (PTM) broadcast, comprising code for:

determining a need for a cell change based on a metric of service quality of the UE relative to the current cell；

initiating a random access procedure with the current cell；

sending a group call service identifier corresponding to the group call service, and neighbor cell measurement results to the current cell；

receiving a target cell indication from the current cell, the target cell providing the group call service by PTM broadcast； and

reselecting to the target cell.
A method of maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in a connected mode, the current cell providing the group call service to the UE by one of point-to-multipoint (PTM) broadcast or MBMS broadcast, said method comprising:

receiving information indicating the group call service；

determining whether any one of a plurality of neighbor cells supports either of PTM broadcast or MBMS broadcast of the group call service； and

sending a handover command to the UE when one of the plurality of neighbor cells support PTM broadcast, the handover command indicating the supporting neighbor cell and including PTM configuration information.
The method of claim 53, further comprising, when none of the plurality of neighbor cells support PTM broadcast or MBMS broadcast of the group call service, determining whether any one of the plurality of neighbor cells support unicast of the group call service.
The method of claim 54, further comprising, when one of the plurality of neighboring cells supports unicast of the group call service, sending a handover command to the UE to initiate a handover to the supporting neighbor cell.
An apparatus for maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in a connected mode, the current cell providing the group call service to the UE by one of point-to-multipoint (PTM) broadcast or MBMS broadcast, said apparatus comprising:

means for receiving information indicating the group call service；

means for determining whether any one of a plurality of neighbor cells supports either of PTM broadcast or MBMS broadcast of the group call service； and

means for sending a handover command to the UE when one of the plurality of neighbor cells support PTM broadcast, the handover command indicating the supporting neighbor cell and including PTM configuration information.
An apparatus for maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in a connected mode, the current cell providing the group call service to the UE by one of point-to-multipoint (PTM) broadcast or MBMS broadcast, said apparatus comprising:

a memory； and

at least one processor coupled to the memory and configured to:

receive information indicating the group call service；

determine whether any one of a plurality of neighbor cells supports either of PTM broadcast or MBMS broadcast of the group call service； and

send a handover command to the UE when one of the plurality of neighbor cells support PTM broadcast, the handover command indicating the supporting neighbor cell and including PTM configuration information.
A computer-readable medium storing computer executable code for maintaining continuity of a group call service by a user equipment (UE) camped on a current cell in a connected mode, the current cell providing the group call service to the UE by one of point-to-multipoint (PTM) broadcast or MBMS broadcast, comprising code for:

receiving information indicating the group call service；

determining whether any one of a plurality of neighbor cells supports either of PTM broadcast or MBMS broadcast of the group call service； and

sending a handover command to the UE when one of the plurality of neighbor cells support PTM broadcast, the handover command indicating the supporting neighbor cell and including PTM configuration information.