WO2018030832A1

WO2018030832A1 - Method and apparatus for user equipment independently reselecting resource based on counter in wireless communication system

Info

Publication number: WO2018030832A1
Application number: PCT/KR2017/008729
Authority: WO
Inventors: 이영대; 서한별; 이선영; 이재욱
Original assignee: 엘지전자 주식회사
Priority date: 2016-08-12
Filing date: 2017-08-11
Publication date: 2018-02-15

Abstract

In a wireless communication system, user equipment (UE) can reselect a sidelink resource used for vehicle-to-everything (V2X) communication. Reselection of a sidelink resource may be triggered by various conditions, and especially can be triggered when the value of a slidelink reselection counter is zero. In particular, the user equipment determines that data for V2X is present in a sidelink traffic channel (STCH), determines that the value of the sidelink resource relocation counter is zero, and reselects the sidelink resource.

Description

Method and apparatus for reselecting resources by terminal itself based on counter in wireless communication system

The present invention relates to wireless communication, and more particularly, to a method and apparatus for reselecting resources by a terminal itself based on a counter in a wireless communication system.

3rd generation partnership project (3GPP) long-term evolution (LTE) is a technology for enabling high-speed packet communication. Many approaches have been proposed to reduce the cost, improve service quality, expand coverage, and increase system capacity for LTE targets. 3GPP LTE is a high level requirement that requires cost per bit, improved service usability, flexible use of frequency bands, simple structure, open interface and proper power consumption of terminals.

LTE-based vehicle-to-everything (V2X) is urgently needed from the market, because the widespread LTE-based network offers the opportunity for the automotive industry to realize the concept of a "connected car." In particular, the market for vehicle-to-vehicle (V2V) communications is expected to have ongoing or initiated related activities, such as research projects, field testing and regulatory work, in some countries or regions, such as the United States, Europe, Japan, Korea, and China. do.

In response to this situation, 3GPP is actively researching and specification of LTE-based V2X. Among the LTE-based V2X, the discussion about PC5-based V2V is the top priority. It is possible to support V2V services based on LTE's PC5 interface with improvements in LTE sidelink (SL) resource allocation, physical hierarchy and synchronization.

The terminal may select itself a SL resource for V2X communication within the resource pool configured by the network. Therefore, methods of selecting or reselecting SL resources for V2X communication need to be discussed.

The present invention provides a method and apparatus for reselecting resources by a terminal itself based on a counter in a wireless communication system. The present invention provides a method and apparatus for a UE to select and / or reselect SL resources for vehicle-to-everything (V2X) communication according to a value of a sidelink resource reselection counter.

In one aspect, a method for reselecting sidelink resources by a user equipment (UE) in a wireless communication system is provided. The method determines that data for vehicle-to-everything (V2X) communication is in a sidelink traffic channel (STCH), determines that the value of the sidelink resource reselection counter is 0, and reselects the sidelink resource. It includes.

The method may further comprise randomly selecting a value between 5 and 15 with equal probability for the sidelink resource reselection counter, and setting the value of the sidelink resource reselection counter to the selected value. When the hybrid automatic repeat request (HARQ) transmission of each transport block (TB) of data for the V2X communication is completed, the value of the sidelink resource reselection counter may be decreased by one.

The method may further include determining the number of HARQ retransmissions within the range configured by the higher layer. The method may further comprise determining an amount of frequency resource within a range configured by a higher layer. Reselecting the sidelink resources may include randomly selecting time and frequency resources from a resource pool indicated by the physical layer.

In another aspect, a user equipment (UE) in a wireless communication system is provided. The terminal includes a memory, a transceiver, and a processor connected to the memory and the transceiver. The processor determines that data for vehicle-to-everything (V2X) communication is in a sidelink traffic channel (STCH), determines that the value of the sidelink resource reselection counter is 0, and reselects the sidelink resource. .

The UE may efficiently select and / or reselect SL resources for V2X communication.

1 shows a structure of a 3GPP LTE system.

2 is a block diagram of a user plane protocol stack of an LTE system.

3 is a block diagram of a control plane protocol stack of an LTE system.

4 illustrates a method for UE to reselect sidelink resources according to an embodiment of the present invention.

5 shows a method for a UE to reselect sidelink resources according to another embodiment of the present invention.

6 illustrates a wireless communication system in which an embodiment of the present invention is implemented.

1 shows a structure of a 3GPP LTE system. Referring to FIG. 1, a 3GPP long-term evolution (LTE) system structure includes one or more user equipment (UE) 10, an evolved-UMTS terrestrial radio access network (E-UTRAN), and an evolved packet core (EPC). Include. The UE 10 is a communication device moved by a user. The UE 10 may be fixed or mobile and may be referred to by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), and a wireless device.

The E-UTRAN includes one or more evolved NodeBs (eNBs) 20, and a plurality of UEs may exist in one cell. The eNB 20 provides an end point of a control plane and a user plane to the UE 10. The eNB 20 generally refers to a fixed station that communicates with the UE 10 and may be referred to in other terms, such as a base station (BS), an access point, and the like. One eNB 20 may be arranged per cell.

Hereinafter, downlink (DL) means communication from the eNB 20 to the UE 10. Uplink (UL) means communication from the UE 10 to the eNB 20. Sidelink (SL) means communication between the UE (10). In the DL, the transmitter may be part of the eNB 20 and the receiver may be part of the UE 10. In the UL, the transmitter may be part of the UE 10 and the receiver may be part of the eNB 20. In the SL, the transmitter and the receiver may be part of the UE 10.

The EPC includes a mobility management entity (MME) and a serving gateway (S-GW). The MME / S-GW 30 is located at the end of the network. The MME / S-GW 30 provides an end point of session and mobility management functionality for the UE 10. For convenience of description, the MME / S-GW 30 is simply expressed as a "gateway", which may include both the MME and the S-GW. A packet dana network (PDN) gateway (P-GW) may be connected to an external network.

The MME includes non-access stratum (NAS) signaling to the eNB 20, NAS signaling security, access stratum (AS) security control, inter CN (node network) signaling for mobility between 3GPP access networks, idle mode terminal reachability ( Control and execution of paging retransmission), tracking area list management (for UEs in idle mode and activation mode), P-GW and S-GW selection, MME selection for handover with MME change, 2G or 3G 3GPP access Bearer management features, including roaming, authentication, and dedicated bearer setup, selection of a serving GPRS support node (SGSN) for handover to the network, public warning system (ETWS) and earthquake and tsunami warning system (CMAS) It provides various functions such as message transmission support. S-GW hosts can be based on per-user packet filtering (eg, through deep packet inspection), legal blocking, terminal IP (Internet protocol) address assignment, transport level packing marking in DL, UL / DL service level charging, gating and It provides various functions of class enforcement, DL class enforcement based on APN-AMBR (access point name aggregate maximum bit rate).

An interface for user traffic transmission or control traffic transmission may be used. The UE 10 and the eNB 20 are connected by a Uu interface. The UEs 10 are connected by a PC5 interface. The eNBs 20 are connected by an X2 interface. The neighboring eNB 20 may have a mesh network structure by the X2 interface. The eNB 20 and the gateway 30 are connected through an S1 interface.

2 is a block diagram of a user plane protocol stack of an LTE system. 3 is a block diagram of a control plane protocol stack of an LTE system. The layer of the air interface protocol between the UE and the E-UTRAN is based on the lower three layers of the open system interconnection (OSI) model, which is well known in communication systems, and includes L1 (first layer), L2 (second layer), and L3 (third layer). Hierarchical).

The physical layer (PHY) belongs to L1. The physical layer provides an information transmission service to a higher layer through a physical channel. The physical layer is connected to a higher layer of a media access control (MAC) layer through a transport channel. Physical channels are mapped to transport channels. Data is transmitted between the MAC layer and the physical layer through a transport channel. Data is transmitted over a physical channel between different physical layers, that is, between a physical layer of a transmitter and a physical layer of a receiver.

The MAC layer, radio link control (RLC) layer, and packet data convergence protocol (PDCP) layer belong to L2. The MAC layer provides a service to an RLC layer, which is a higher layer, through a logical channel. The MAC layer provides data transfer services on logical channels. The RLC layer supports reliable data transmission. Meanwhile, the function of the RLC layer may be implemented as a functional block inside the MAC layer, in which case the RLC layer may not exist. The PDCP layer introduces an IP packet, such as IPv4 or IPv6, over a relatively low bandwidth air interface to provide header compression that reduces unnecessary control information so that the transmitted data is transmitted efficiently.

The radio resource control (RRC) layer belongs to L3. The RRC layer at the bottom of L3 is defined only in the control plane. The RRC layer is responsible for the control of logical channels, transport channels, and physical channels in connection with configuration, re-configuration, and release of radio bearers (RBs). RB means a service provided by L2 for data transmission between the UE and the E-UTRAN.

Referring to FIG. 2, the RLC and MAC layers (end at the eNB at the network side) may perform functions such as scheduling, ARQ, and hybrid automatic repeat request (HARQ). The PDCP layer (terminating at the eNB at the network side) may perform user plane functions such as header compression, integrity protection and encryption.

Referring to FIG. 3, the RLC / MAC layer (end at eNB at network side) may perform the same functions for the control plane. The RRC layer (terminated at the eNB at the network side) may perform functions such as broadcast, paging, RRC connection management, RB control, mobility functionality, and UE measurement reporting and control. The NAS control protocol (terminated at the gateway's MME at the network side) may perform functions such as SAE bearer management, authentication, LTE_IDLE mobility management, paging start in LTE_IDLE, and security control for signaling between the gateway and the UE.

The physical channel transmits signaling and data between the physical layer of the UE and the physical layer of the eNB through radio resources. The physical channel is composed of a plurality of subframes in the time domain and a plurality of subcarriers in the frequency domain. One subframe of 1ms consists of a plurality of symbols in the time domain. A specific symbol of the corresponding subframe, for example, the first symbol of the subframe may be used for the PDCCH. The PDCCH may carry dynamically allocated resources, such as a physical resource block (PRB) and modulation and coding schemes (MCS).

The DL transport channel is a broadcast channel (BCH) used for transmitting system information, a paging channel (PCH) used for paging a UE, and a downlink shared channel (DL-SCH) used for transmitting user traffic or control signals. , Multicast channel (MCH) used for multicast or broadcast service transmission. The DL-SCH supports dynamic link adaptation and dynamic / semi-static resource allocation by varying HARQ, modulation, coding and transmit power. In addition, the DL-SCH may enable the use of broadcast and beamforming throughout the cell.

The UL transport channel generally includes a random access channel (RACH) used for initial access to a cell, an uplink shared channel (UL-SCH) used for transmitting user traffic or control signals. The UL-SCH supports dynamic link adaptation with HARQ and transmit power and potential changes in modulation and coding. In addition, the UL-SCH may enable the use of beamforming.

Logical channels are classified into control channels for information transmission in the control plane and traffic channels for information transmission in the user plane according to the type of information to be transmitted. That is, a set of logical channel types is defined for different data transfer services provided by the MAC layer.

The control channel is used only for conveying information in the control plane. The control channel provided by the MAC layer includes a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and a dedicated control channel (DCCH). BCCH is a DL channel for broadcasting system control information. PCCH is a DL channel for the transmission of paging information, and is used when the network does not know the location of the cell unit of the UE. CCCH is used by the UE when it does not have an RRC connection with the network. The MCCH is a one-to-many DL channel used for transmitting multimedia broadcast multicast services (MBMS) control information from the network to the UE. DCCH is a one-to-one bidirectional channel used by a UE having an RRC connection for transmission of dedicated control information between the UE and the network.

The traffic channel is used only for conveying information in the user plane. The traffic channel provided by the MAC layer includes a dedicated traffic channel (DTCH) and a multicast traffic channel (MTCH). DTCH is used for transmission of user information of one UE on a one-to-one channel and may exist in both UL and DL. MTCH is a one-to-many DL channel for transmitting traffic data from the network to the UE.

The UL connection between the logical channel and the transport channel includes a DCCH that can be mapped to the UL-SCH, a DTCH that can be mapped to the UL-SCH, and a CCCH that can be mapped to the UL-SCH. The DL connection between logical channel and transport channel is BCCH which can be mapped to BCH or DL-SCH, PCCH which can be mapped to PCH, DCCH which can be mapped to DL-SCH, DTCH which can be mapped to DL-SCH, MCH MCCH that can be mapped to and MTCH that can be mapped to MCH.

The RRC state indicates whether the RRC layer of the UE is logically connected with the RRC layer of the E-UTRAN. The RRC state may be divided into two types, such as an RRC connected state (RRC_CONNECTED) and an RRC idle state (RRC_IDLE). In RRC_IDLE, while the UE designates a discontinuous reception (DRX) set by the NAS, the UE may receive a broadcast of system information and paging information. In addition, the UE may be assigned an ID for uniquely designating the UE in the tracking area, and perform public land mobile network (PLMN) selection and cell reselection. Also in RRC_IDLE, no RRC context is stored at the eNB.

In RRC_CONNECTED, it is possible for the UE to have an E-UTRAN RRC connection and context in the E-UTRAN to send data to the eNB and / or receive data from the eNB. In addition, the UE may report channel quality information and feedback information to the eNB. In RRC_CONNECTED, the E-UTRAN may know the cell to which the UE belongs. Therefore, the network may transmit data to and / or receive data from the UE, and the network may inter-RAT with a GSM EDGE radio access network (GERAN) through the UE's mobility (handover and network assisted cell change (NACC). radio access technology (cell change indication), and the network may perform cell measurement for a neighboring cell.

In RRC_IDLE, the UE specifies a paging DRX cycle. Specifically, the UE monitors a paging signal at a specific paging occasion for each UE specific paging DRX cycle. Paging opportunity is the time period during which the paging signal is transmitted. The UE has its own paging opportunity. The paging message is transmitted on all cells belonging to the same tracking area (TA). When a UE moves from one TA to another TA, the UE may send a tracking area update (TAU) message to the network to update its location.

Sidelinks are described. Sidelink is an interface between UEs for sidelink communication and sidelink discovery. Sidelinks correspond to PC5 interfaces. Sidelink communication is an AS feature that enables two or more neighboring UEs to directly communicate Proximity-based services (ProSe) using E-UTRA technology without going through any network node. Sidelink discovery is an AS feature that allows two or more neighboring UEs to directly discover ProSe using E-UTRA technology without going through any network node.

The sidelink physical channel includes a physical sidelink broadcast channel (PSBCH) for transmitting system and synchronization related information transmitted from the UE, a physical sidelink discovery channel (PSCH) for transmitting a sidelink discovery message transmitted from the UE, and a side transmitted from the UE. A physical sidelink control channel (PSCCH) for transmitting a control signal for link communication and a physical sidelink shared channel (PSSCH) for transmitting data for sidelink communication transmitted from a UE. Sidelink physical channels are mapped to sidelink transport channels. PSBCH is mapped to a sidelink broadcast channel (SL-BCH). The PSDCH is mapped to a sidelink discovery channel (SL-DCH). PSSCH is mapped to a sidelink shared channel (SL-SCH).

In sidelinks, logical channels are classified into control channels for information transmission in the control plane and traffic channels for information transmission in the user plane. The sidelink control channel includes a sidelink broadcast control channel (SBCCH), which is a sidelink channel for broadcasting sidelink system information from one UE to another UE. SBCCH is mapped to SL-BCH. The sidelink traffic channel includes a sidelink traffic channel (STCH), which is a point-to-multipoint channel for the transmission of user information from one UE to another. STCH is mapped to SL-SCH. This channel can only be used by UEs capable of sidelink communication.

Sidelink communication is a communication mode in which a UE can communicate directly via a PC5 interface. This communication mode is supported when the UE is served by the E-UTRAN and when the UE is outside of E-UTRA coverage. Only UEs authorized to be used for public safety tasks can perform sidelink communication.

The UE supporting sidelink communication may operate in the following two modes for resource allocation. The first mode is scheduled resource allocation. Scheduled resource allocation may be called mode 1. In mode 1, the UE needs to be in RRC_CONNECTED to send data. The UE requests a transmission resource from the eNB. The eNB schedules transmission resources for transmission of sidelink control information and data. The UE transmits a scheduling request (dedicated scheduling request (D-SR) or random access) to the eNB and then sends a sidelink buffer status report (BSR). Based on the sidelink BSR, the eNB can determine that the UE has data for sidelink communication transmission and can estimate the resources required for transmission. The eNB may schedule transmission resources for sidelink communication using the configured sidelink radio network temporary identity (SL-RNTI).

The second mode is UE autonomous resource selection. UE autonomous resource selection may be referred to as mode 2. In mode 2, the UE itself selects a resource from a resource pool, and selects a transmission format for transmitting sidelink control information and data. There may be up to eight resource pools preconfigured for out of coverage operations or provided by RRC signaling for in-coverage operations. Each resource pool may be associated with one or more ProSe per-packet-priority (PPPP). For transmission of a MAC protocol data unit (PDU), the UE selects a resource pool that has one of the same PPPPs as that of the logical channel having the highest PPPP among the logical channels identified in the MAC PDU. Sidelink control pools and sidelink data pools are associated one-to-one. If a resource pool is selected, the selection is valid for the entire sidelink control period. After the sidelink control period ends, the UE may select the resource pool again.

The UE is considered to be in coverage for sidelink communication whenever it detects a cell on a public safety ProSe carrier. If the UE is out of coverage for sidelink communication, the UE may only use mode 2. If the UE is in coverage for sidelink communication, mode 1 or mode 2 may be used depending on the eNB configuration. If the UE is in coverage for sidelink communication, the UE should only use mode 1 indicated by the eNB configuration, unless one of the exceptional cases occurs. If an exception occurs, the UE may temporarily use mode 2, even if it is configured to use mode 1. The resource pool to be used in exceptional cases may be provided by the eNB.

The cell of the public safety ProSe carrier may select one of the following two options. First, a cell of a public safety ProSe carrier may provide a transmission resource pool for mode 2 in SIB18. A UE that is allowed side link communication may use this resource for side link communication in RRC_IDLE in a cell of the same carrier (ie, public safety ProSe carrier). A UE authorized for sidelink communication may use this resource for sidelink communication in RRC_IDLE or RRC_CONNECTED in a cell of another carrier.

Alternatively, the cell of the public safety ProSe carrier may indicate that the SIB18 supports sidelink communication but does not provide a transmission resource. The UE needs to enter RRC_CONNECTED to perform sidelink communication transmission. In this case, the cell of the public safety ProSe carrier may provide an exceptional transmission resource pool for mode 2 to be used by the UE as a broadcast signal in exceptional cases. The UE of RRC_CONNECTED authorized to perform sidelink communication transmission instructs the serving eNB that it wants to perform sidelink communication transmission. The eNB uses the UE context received from the MME to verify whether the UE is authorized for side link communication transmission. The eNB may configure the UE by dedicated signaling with a transmission resource pool for mode two. This resource can be used without limitation while the UE is in RRC_CONNECTED. Alternatively, the eNB may configure the UE to use the exceptional transmission resource pool for mode 2 which the UE is allowed to use only in exceptional cases, otherwise it depends on mode 1.

When the UE is out of coverage for sidelink communication, the set of transmit and receive resource pools for sidelink control information is preconfigured in the UE. When the UE is in coverage for sidelink communication, the resource pool for sidelink control information is configured as follows. The resource pool used for reception is configured by the eNB via RRC in broadcast signaling. The resource pool used for transmission is configured by the eNB via RRC in dedicated or broadcast signaling when mode 2 is used and by the eNB via RRC in dedicated signaling when mode 1 is used. The eNB schedules a specific resource for sidelink control information transmission in the configured reception pool.

When the UE is out of coverage for sidelink communication, the set of transmit and receive resource pools for sidelink data is preconfigured in the UE. When the UE is in coverage for sidelink communication, the resource pool for sidelink data is configured as follows. When mode 2 is used, the resource pool used for transmission and reception is configured by the eNB via RRC in dedicated or broadcast signaling. If mode 1 is configured, there is no resource pool for transmission and reception.

Sidelink discovery is defined as the procedure used by a UE that supports sidelink discovery to discover other UEs in proximity using E-UTRA direct radio signals over PC5. Sidelink discovery is supported both when the UE is served by the E-UTRAN and when the UE is out of E-UTRA coverage. Outside the E-UTRA range, only ProSe-enabled public safety UEs can perform sidelink discovery. For public safety sidelink discovery, the allowed frequencies are preconfigured at the UE and are used even if the UE is out of range of E-UTRA at that frequency. The preconfigured frequency is the same frequency as the public safety ProSe carrier.

There are two types of resource allocation in discovery message notifications. The first is UE autonomous resource selection, which is a resource allocation procedure in which resources for advertising discovery messages are allocated on a non-UE specific basis. UE autonomous resource selection may be referred to as type 1. In type 1, the eNB provides the UE with a resource pool configuration used for the announcement of the discovery message. The configuration may be signaled by broadcast or dedicated signaling. The UE autonomously selects a radio resource from the indicated resource pool and announces a discovery message. The UE may announce a discovery message on a randomly selected discovery resource during each discovery period.

The second is scheduled resource allocation, which is a resource allocation procedure in which resources for advertising discovery messages are allocated on a UE specific basis. Scheduled resource allocation may be referred to as type 2. In type 2, a UE of RRC_CONNECTED may require a resource to announce a discovery message from an eNB via RRC. The eNB allocates resources via RRC. Resources are allocated within resource pools configured in the UE for notification.

For the UE in RRC_IDLE, the eNB may select one of the following options. The eNB may provide a resource pool for type 1 based discovery message notification in SIB19. UE authorized for sidelink discovery uses this resource to announce a discovery message in RRC_IDLE. Or, the eNB may indicate that it supports sidelink discovery in SIB19 but does not provide resources for discovery message notification. The UE needs to enter RRC_CONNECTED to request resources for discovery message notification.

For a UE in RRC_CONNECTED, the UE authorized to perform sidelink discovery announcement instructs the eNB that it wants to perform sidelink discovery announcement. The UE may also inform the eNB of the desired frequency for sidelink discovery announcement. The eNB uses the UE context received from the MME to verify whether the UE is authorized for sidelink discovery announcement. The eNB may configure a type 1 resource pool for discovery message notification in the UE through dedicated signaling. The eNB may configure a resource pool in the form of time and frequency index with dedicated resources through dedicated RRC signaling for discovery message notification. Resources allocated by the eNB via dedicated signaling are valid until the eNB reconfigures the resources by RRC signaling or the UE enters RRC_IDLE.

Authorized receiving UEs in RRC_IDLE and RRC_CONNECTED monitor the type 1 resource pool and the type 2 resource pool. The eNB provides a resource pool configuration used for monitoring in-band, inter-frequency discovery message of the same or another PLMN cell in RRC signaling (SIB19). RRC signaling (SIB19 or dedicated) may include a detailed sidelink discovery configuration used for the announcement of sidelink discovery in a cell within frequency, between frequencies of the same or different PLMNs.

Describes vehicle-to-everything (V2X) communication. There are three types of V2X communication: vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, and vehicle-to-pedestrian (V2P) communication. These three types of V2X can use "collaboration consciousness" to provide more intelligent services for end users. This allows vehicle, road side unit (RSU) and transportation entities such as pedestrians to collect knowledge about their local environment (for example, information received from other vehicles or sensor equipment in close proximity), and can be used for collaborative collision alerts or autonomous driving. This means that knowledge can be processed and shared to provide intelligent services.

V2X service is a type of communication service that includes a transmitting or receiving UE using a V2V application over 3GPP transmission. The V2X service may be divided into a V2V service, a V2I service, a V2P service, and a vehicle-to-network (V2N) service according to a counterpart who participated in the communication. V2V service is a type of V2X service that is a UE that uses V2V applications on both sides of the communication. A V2I service is a type of V2X service that uses a V2I application, with one side of communication being a UE and the other side being an RSU. The RSU is an entity supporting a V2I service that can transmit / receive with a UE using a V2I application. RSU is implemented in an eNB or a fixed UE. V2P service is a type of V2X service that is a UE that uses V2P applications on both sides of the communication. A V2N service is a type of V2X service in which one side of communication is a UE and the other is a serving entity, all using V2N applications and communicating with each other via an LTE network entity.

In V2V, the E-UTRAN allows UEs in close proximity to each other to exchange V2V related information using E-UTRA (N) when permit, authorization and proximity criteria are met. Proximity criteria may be configured by a mobile network operator (MNO). However, the UE supporting the V2V service may exchange such information when it is provided or not provided by the E-UTRAN supporting the V2X service. The UE supporting the V2V application sends application layer information (eg, about its location, dynamics and attributes as part of the V2V service). The V2V payload must be flexible to accommodate different content, and information can be sent periodically depending on the configuration provided by the MNO. V2V is mainly broadcast based. V2V includes the direct exchange of V2V related application information between different UEs, and / or due to the limited direct communication range of V2V, V2V is an infrastructure supporting V2X service for V2V related application information between different UEs (eg For example, the exchange through the RSU, application server, etc.).

In V2I, the UE supporting the V2I application transmits application layer information to the RSU. The RSU transmits application layer information to the UE supporting the UE group or the V2I application.

In V2P, the E-UTRAN allows UEs in close proximity to each other to exchange V2P related information using the E-UTRAN when permit, authorization and proximity criteria are met. Proximity criteria may be constructed by the MNO. However, the UE supporting the V2P service may exchange this information even when not serviced by the E-UTRAN supporting the V2X service. The UE supporting the V2P application transmits application layer information. Such information may be broadcast by vehicle UEs (eg, alerting pedestrians) that support V2X services and / or pedestrian UEs (eg, alerting vehicles) that support V2X services. V2P involves exchanging V2V related application information directly between different UEs (one vehicle, another pedestrian), and / or due to the limited direct communication range of V2P, V2P is a V2P related application between different UEs. This involves exchanging information through infrastructures that support V2X services (eg, RSUs, application servers, etc.).

In V2X communication, messages such as common awareness messages (CAM), decentralized environmental notification messages (DENM), or basic safety messages (BSM) may be transmitted. The CAM includes information such as the type, location, speed, and direction of the vehicle, and can be broadcast periodically by all vehicles. The DENM includes information on a type of a specific event, a region in which a specific event occurs, and may be broadcast by an RSU or a vehicle. The BSM is included in the US J2735 safety message and has similar characteristics to CAM. BSM can provide emergency brake warnings, forward collision warnings, intersection safety assistance, blind spot and lane change warnings, overtaking warnings, and out of control warnings.

The UE may select the SL resource for V2X communication by itself in the resource pool configured by the network. That is, the UE may select the SL resource for V2X communication by itself in mode 2 and perform V2X communication through the corresponding SL resource. However, SL resources for V2X communication may be selected based on sensing. More specifically, the UE may perform sensing for (re) selection of SL resources. Based on the sensing result, the UE specific SL resource may be (re) selected and a plurality of SL resources may be reserved. UE autonomous resource selection based on sensing for V2X communication may be referred to as V2V mode 2.

Many discussions are underway for the selection and / or reselection of SL resources. Hereinafter, various aspects of SL resources for V2X communication according to various embodiments of the present invention will be described.

1. SL resource reselect trigger condition

For V2V mode 2, the following may be proposed for the condition that triggers the resource reselection. Reselection can be triggered if any of the following conditions are met: When resource reselection is triggered can be specified at the MAC layer.

(1) If the counter satisfies the expiration condition, the MAC layer may trigger SL resource reselection. A new counter, SL resource reselection counter SL_RESOURCE_RESELECTION_COUNTER, may be introduced for resource reselection. If the value of the SL resource reselection counter is 0, the MAC layer may trigger resource reselection. If resource reselection is triggered, the UE may arbitrarily select a value between 5-15 with equal probability for the SL resource reselection counter. That is, the SL resource reselection counter may be reset when reselection is triggered for all semi-permanently selected resources. The value of the SL resource reselection counter may decrease by one when HARQ (re) transmission of each TB is completed. More specifically, when the value of RETX_NUMBER_SLSCH indicating the number of retransmissions of the SL-SCH is equal to the number of HARQ retransmissions, the value of the SL resource reselection counter may be decreased by one.

(2) If the current SL grant cannot accommodate the TB using the maximum allowed MCS within the range configured by the higher layer, the MAC layer may trigger the SL resource reselection. That is, the UE may use the maximum allowed MCS to identify that the TB does not fit within the current resource allocation, and trigger the SL resource reselection.

(3) If one or more resource pools are (re) configured by RRC, the MAC layer may trigger SL resource reselection. The eNB may implicitly trigger reselection whenever the resource pool configuration changes. Dedicated signaling may be used for the UE of RRC_CONNECTED and broadcast signaling may be used for the UE of RRC_IDLE.

One embodiment of the operation of the UE for SL resource selection and reselection, combining the above-described SL resource reselection trigger conditions, is shown in Table 1.

For V2X communication, if data is available on the STCH for transmission over the SL-SCH, the MAC entity does the following: 1> SL_RESOURCE_RESELECTION_COUNTER = 0; Or 1> the current SL grant cannot accommodate the TB using the maximum allowed MCS within the range configured by the higher layer; Or 1> one or more resource pools are (re) configured by a higher layer; 2> randomly select a value between 5 and 15 with equal probability and set SL_RESOURCE_RESELECTION_COUNTER to the selected value.

2. Reselect resources to account for delay requirements

The generation time of the periodic message can be adjusted over time. This coordination affects the delay, so that the UE can transmit assistance information including the period and time offset for SL semi-persistent scheduling (SPS) operation. This help information can trigger reactivation of the SL SPS to meet delay requirements.

On the other hand, in V2V mode 2, the UE selects time and frequency resources from the resource pool selected for periodic transmission of V2X messages, which occur every 100ms, for example. The UE then determines the set of subframes in which the TB is sent for each TB that is likely to correspond to one V2X message. Thus, similar to SL SPS, a change in message generation time may need to trigger resource reselection to meet delay requirements. That is, the change of the message generation time may be regarded as a trigger condition of additional resource reselection. Thus, reselection may be triggered if the SL grant does not meet the delay requirement for TB.

For example, when the CAM message generation time is adjusted to a time of +30 ms with the same period (eg 100 ms), the UE may reselect the time and frequency resources from the selected resource pool. In addition, when the period of the CAM message changes from 100ms to 500ms, the UE may reselect time and frequency resources from the selected resource pool according to the new period.

In consideration of the above-described delay requirements, an embodiment of the operation of the UE for SL resource selection and reselection is shown in Table 2.

For V2X communication, if data is available on the STCH for transmission over the SL-SCH, the MAC entity does the following: 1> SL_RESOURCE_RESELECTION_COUNTER = 0; Or 1> the current SL grant cannot accommodate the TB using the maximum allowed MCS within the range configured by the higher layer; Or 1> one or more resource pools are (re) configured by a higher layer; Or 1> if the SL grant cannot satisfy the delay requirement for TB; 2> randomly select a value between 5 and 15 with the same probability and set SL_RESOURCE_RESELECTION_COUNTER to the selected value.

Meanwhile, the UE performs sensing for a certain period between the subframe 'n-a' and the subframe 'n-b', performs resource selection in the subframe 'n', and is connected in the subframe 'n + d'. In order to indicate data transmission, a scheduling assignment (SA) may be transmitted in a subframe 'n + c'. More specifically, when resource selection / reselection is triggered at TTI 'n' in V2V mode 2, the UE may perform sensing at least TTI 'n-a' and TTI 'n-b'. In this case, a and b are integers, a> b> 0, and a and b may be common to all V2V UEs. The UE may select a time-frequency resource for the PSSCH. In addition, in V2V mode 2, the UE may transmit an SA indicating related data to be transmitted in TTI 'n + d' in TTI 'n + c'. c and d are integers and c≤≤d. In addition, the UE may indicate whether to reuse the signaled frequency resource for transmission in TTI 'n + d' for potential transmission of another TB in TTI 'n + e'. e is an integer and d <e.

That is, the V2V delay in the SL is determined as 'n + d'. Therefore, when the UE performs resource selection / reselection, the UE needs to check whether the selected SL grant satisfies the V2V delay requirement (ie, 100 ms) in consideration of the time that the message reaches the AS layer. That is, the UE should select time and frequency resources for SL-SCH and SL control information (SCI) of the SL grant that satisfy the delay requirement in consideration of the time when the message reaches the AS layer.

The physical layer may determine candidate resources (by excluding unavailable resources) based on sensing from a pool of resources selected by the MAC layer. The MAC layer then randomly selects time and frequency resources for SL-SCH and SCI of the SL grant. Since the delay requirement must be satisfied for each TB (ie, one message), the physical layer must be able to provide only candidate resources that can satisfy the delay requirement. Otherwise, the physical layer may provide only candidate resources that cannot meet the delay requirements. Thus, the MAC layer can determine the maximum allowed PSSCH transmission time that satisfies the delay requirement (ie, d_max) for each TB. Then, the physical layer may provide only the candidate resources to the MAC layer that can satisfy the delay requirement based on the maximum allowed PSSCH transmission time.

In consideration of the maximum allowable PSSCH transmission time described above, one embodiment of the operation of the UE for SL grant reception and SCI transmission is shown in Table 3.

If the MAC entity is configured by a higher layer to transmit using one or several resource pools, then the MAC entity performs the following for each TB transmission: ...- MCS within the range configured by the higher layer. Determine the maximum allowed PSSCH transmission time that satisfies the delay requirements; if triggered, performs SL resource selection and resource reselection.

One embodiment of the operation of the UE for SL resource selection and reselection considering the maximum allowable PSSCH transmission time described above is shown in Table 4.

For V2X communication, if data is available on the STCH for transmission on the SL-SCH, the MAC entity does the following: 1> SL_RESOURCE_RESELECTION_COUNTER 0; Or 1> the current SL grant cannot accommodate the TB using the maximum allowed MCS within the range configured by the higher layer; Or 1> one or more resource pools are (re) configured by higher layers; 2> randomly select values between 5 and 15 with equal probability, and set SL_RESOURCE_RESELECTION_COUNTER to the selected values; 2> within the range configured by higher layers Determines the number of HARQ retransmissions and the amount of frequency resources within the range configured by the higher layer; 2> of the SL grant from the selected resource pool, except for the resources excluded by the physical layer according to the determined maximum allowed PSSCH transmission time; Randomly selects time and frequency resources for SL-SCH and SCI. The random function must be able to select each of the allowed choices with equal probability.

3. Resource selection and reselection for each logical channel

The SCI may explicitly include priority information. This priority information may be used for sensing based resource selection. On the other hand, one logical channel can be used to carry a CAM message at a relatively low priority, while the other logical channel can be used to carry a DENM message at a relatively high priority. Thus, one SCI and associated data transmission can be used for either a CAM message or a DENM message.

This resource (re) selection and transport mechanism can work well when the SL grant is selected per logical channel. That is, one resource (re) selection and transmission procedure for the CAM and another resource (re) selection and transmission procedure for the DEN may be performed in parallel. Accordingly, in the V2V mode 2, an SL grant reception and SCI transmission procedure and an SL resource selection and reselection procedure may occur for each logical channel.

An embodiment of the operation of the UE considering each logical channel described above is shown in Table 5.

For V2X communication, the SL grant is selected for each SL logical channel as follows: If the MAC entity is configured by the upper layer to transmit using one or several resource pools, then the MAC entity is assigned to the transmission of each TB. Do the following: ...

4. Select resource pool

In the existing MAC procedure, when the MAC entity is configured to transmit using one or more resource pools by the higher layer, the MAC layer may select a resource pool to use from the resource pool configured by the RRC layer. This cross-layer operation may be performed for V2X communication.

In addition, region-based resource pool selection for V2X communication may be introduced. Thus, if the UE determines the area where the UE is located, the UE can select a resource pool corresponding to that area. The area may be determined in the upper layer rather than the MAC layer. The MAC layer may be informed about the area determined in the upper layer.

An embodiment of the operation of the UE for resource pool selection described above is shown in Table 6.

For V2X communication, the SL grant is selected as follows: 1> If the MAC entity is configured by a higher layer to transmit using one or several resource pools, the MAC entity performs the following for each TB transmission: 2> If the upper tier is configured to use a single resource pool: 3> Select the resource pool to use; 2> Otherwise, if the upper tier is configured to use multiple resource pools with realms: 3> The parent From the resource pool configured by the hierarchy, select the resource pool to use that corresponds to the area indicated by the higher layer. 2> Select the MCS within the range configured by the higher layer; 2> Select the SL resource, if triggered and Perform resource reselection; 2> use the selected SL grant to determine the set of subframes in which SCI and TB transmissions occur; 2> SL configured the selected SL grant 2) The SL grant and associated HARQ information configured in this TTI are forwarded to the SL HARQ entity.

5. Resource Reselection Triggered by UL Transmission or ProSe Discovery

V2V transmission may not occur when overlapping with UL transmission or discovery transmission. Accordingly, resource reselection may be triggered by UL transmission or ProSe discovery. One embodiment of the operation of the UE for SL resource selection and reselection considering the UL transmission or ProSe discovery described above is shown in Table 7.

For V2X communication, if data is available on the STCH for transmission on the SL-SCH, the MAC entity does the following: 1> UL transmission is present at the time of transmission, and the MAC entity is on UL transmission and SL-SCH. When the transmission cannot be performed simultaneously at the time of transmission; Or 1> when there is transmission or reception on the PSDCH at the time of transmission; Or 1> if there is an SL discovery gap for transmission at the time of transmission: 2> the UE shall trigger resource selection or reselection for transmission of each TTI, each subframe or each TB as follows: Randomly select a value between 5 and 15 and set SL_RESOURCE_RESELECTION_COUNTER to the selected value; 2> determine the number of HARQ retransmissions within the range configured by the higher layer and the amount of frequency resources within the range configured by the higher layer. ; 2> randomly selects time and frequency resources for SL-SCH and SCI of the SL grant from the selected resource pool, except for the resources excluded by the physical layer according to the determined maximum allowed PSSCH transmission time. The random function must be able to select each of the allowed selections with equal probability. 2> Use the selected SL grant to determine the set of subframes in which the transmission of the SCI and the transmission of the TB occur; 2) The SL grant and associated HARQ information configured in this TTI are forwarded to the SL HARQ entity.

6. Resource reselection except for resources that overlap UL transmission or SL discovery

V2V transmission may not occur when overlapping with UL transmission or discovery transmission. Thus, the UE can perform resource reselection except for resources that overlap with UL transmission or SL discovery. One embodiment of the operation of the UE for SL resource selection and reselection considering the UL transmission or SL discovery described above is shown in Table 8.

When resource selection or reselection is triggered, the UE (preferably for the physical layer) does the following (preferably for a logical channel): 1> Selects a resource pool (if several pools are configured by the eNB); > Excludes resources with UL transmission, resources with transmission or reception on PSDCH, and resources with SL discovery gap for transmission; 1> SL-SCH of the SL grant from the selected resource pool, excluding the excluded resources And arbitrarily select time and frequency resources for the SCI; 1> determine the set of subframes in which the transmission of the SCI and the transmission of the TB occur using the selected SL grant; 1> consider the selected SL grant as the configured SL grant. ; 1> delivers the SL grant and associated HARQ information configured in this TTI to the SL HARQ entity.

4 illustrates a method for UE to reselect sidelink resources according to an embodiment of the present invention. The above description of the present invention can be applied to this embodiment.

In step S100, the UE determines that data for V2X communication is in the STCH. In step S110, the UE determines that the value of the sidelink resource reselection counter is zero. In step S120, the UE reselects the sidelink resource.

When the UE reselects a sidelink resource, the UE randomly selects a value between 5 and 15 with the same probability for the sidelink resource reselection counter, and sets the value of the sidelink resource reselection counter to the selected value. Can be. When HARQ transmission of each TB of data for the V2X communication is completed, the value of the sidelink resource reselection counter may be decreased by one.

In addition, if the UE reselects the sidelink resources, the UE may determine the number of HARQ retransmissions within the range configured by the higher layer. The UE may determine the amount of frequency resource within the range configured by the higher layer. Reselecting the sidelink resources may include randomly selecting time and frequency resources from a resource pool indicated by the physical layer.

The resource pool indicated by the physical layer may not include resources excluded by the physical layer according to the delay requirement of the V2X communication. Resources excluded by the physical layer may be determined according to the maximum allowed PSSCH transmission time. The sidelink resource reselection may be performed for each sidelink logical channel.

5 shows a method for a UE to reselect sidelink resources according to another embodiment of the present invention. The above description of the present invention can be applied to this embodiment.

In step S200, the UE determines that data for V2X communication is in the STCH. In step S210, the UE determines that one or more resource pools are configured from higher layers. In step S220, the UE reselects the sidelink resource.

If the UE reselects the sidelink resource, the UE may randomly select a value between 5 and 15 with equal probability for the sidelink resource reselection counter, and set the value of the sidelink resource reselection counter to the selected value. have. When HARQ transmission of each TB of data for the V2X communication is completed, the value of the sidelink resource reselection counter may be decreased by one.

The eNB 800 includes a processor 810, a memory 820, and a transceiver 830. Processor 810 may be configured to implement the functions, processes, and / or methods described herein. Layers of the air interface protocol may be implemented by the processor 810. The memory 820 is connected to the processor 810 and stores various information for driving the processor 810. The transceiver 830 is connected to the processor 810 to transmit and / or receive a radio signal.

The UE 900 includes a processor 910, a memory 920, and a transceiver 930. Processor 910 may be configured to implement the functions, processes, and / or methods described herein. Layers of the air interface protocol may be implemented by the processor 910. The memory 920 is connected to the processor 910 and stores various information for driving the processor 910. The transceiver 930 is connected to the processor 910 to transmit and / or receive a radio signal.

Processors

810 and 910 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The

memories

820 and 920 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media and / or other storage devices. The

transceivers

830 and 930 may include a baseband circuit for processing radio frequency signals. When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in the

memory

820, 920 and executed by the

processor

810, 910. The

memories

820 and 920 may be inside or outside the

processors

810 and 910, and may be connected to the

processors

810 and 910 by various well-known means.

In the exemplary system described above, methods that may be implemented in accordance with the above-described features of the present invention have been described based on a flowchart. For convenience, the methods have been described as a series of steps or blocks, but the claimed features of the present invention are not limited to the order of steps or blocks, and certain steps may occur in the same order as other steps and in a different order than described above. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

Claims

A method for reselecting a sidelink resource by a user equipment (UE) in a wireless communication system,

Determine that data for vehicle-to-everything (V2X) communication is in a sidelink traffic channel (STCH);

Determine that the value of the sidelink resource reselection counter is zero; And

Reselecting the sidelink resources.
The method of claim 1,

Randomly select a value between 5 and 15 with equal probability for the sidelink resource reselection counter; And

Setting the value of the sidelink resource reselection counter to the selected value.
The method of claim 1,

And when the hybrid automatic repeat request (HARQ) transmission of each transport block (TB) of data for the V2X communication is completed, a value of the sidelink resource reselection counter is decreased by one.
The method of claim 1,

Determining the number of HARQ retransmissions within the range configured by the higher layer.
The method of claim 1,

Determining the amount of frequency resource within a range configured by a higher layer.
The method of claim 1,

Reselecting the sidelink resources includes randomly selecting time and frequency resources from a resource pool indicated from a physical layer.
The method of claim 1,

The resource pool indicated by the physical layer does not include resources excluded by the physical layer according to the delay requirement of the V2X communication.
The method of claim 1,

The resource excluded by the physical layer is determined according to the maximum allowable physical sidelink shared channel (PSSCH) transmission time.
The method of claim 1,

The sidelink resource reselection is performed for each sidelink logical channel.
In a user equipment (UE) in a wireless communication system,

Memory;

A transceiver; And

A processor connected to the memory and the transceiver;

The processor,

Determine that data for vehicle-to-everything (V2X) communication is in a sidelink traffic channel (STCH);

Determine that the value of the sidelink resource reselection counter is zero; And

Terminal for reselecting the sidelink resources.
The method of claim 10,

The processor,

Randomly select a value between 5 and 15 with equal probability for the sidelink resource reselection counter; And

And setting a value of the sidelink resource reselection counter to the selected value.
The method of claim 10,

And when the hybrid automatic repeat request (HARQ) transmission of each transport block (TB) of data for the V2X communication is completed, a value of the sidelink resource reselection counter is decreased by one.
The method of claim 10,

And the processor determines the number of HARQ retransmissions within a range configured by a higher layer.
The method of claim 10,

And the processor determines an amount of frequency resource within a range configured by a higher layer.
The method of claim 10,

And reselecting the sidelink resources includes randomly selecting time and frequency resources from a resource pool indicated by a physical layer.