WO2021142923A1

WO2021142923A1 - An efficient scheme for fountain codes over multiple radio access technologies

Info

Publication number: WO2021142923A1
Application number: PCT/CN2020/080534
Authority: WO
Inventors: Changlong Xu; Hao Xu; Tao Luo; Jian Li; Liangming WU; Kangqi LIU
Original assignee: Qualcomm Incorporated
Priority date: 2020-01-17
Filing date: 2020-03-21
Publication date: 2021-07-22
Also published as: WO2021142773A1

Abstract

Certain aspects of the present disclosure provide techniques for efficiently transmitting data over multiple radio access technologies (RATs), for example, between a base station and a user equipment (UE).

Description

AN EFFICIENT SCHEME FOR FOUNTAIN CODES OVER MULTIPLE RADIO ACCESS TECHNOLOGIES

Cross-reference to related applications

This application claims priority to PCT Application No. PCT/CN2020/072752, filed January 17, 2020, which is assigned to the assignee hereof and hereby expressly incorporated by reference herein in its entirety as if fully set forth below and for all applicable purposes.

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for efficiently transmitting data over multiple radio access technologies (RATs) .

Description of Related Art

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These 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, etc. ) . Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, 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, to name a few.

In some examples, a wireless multiple-access communication system may include a number of base stations (BSs) , which are each capable of simultaneously supporting communication for multiple communication devices, otherwise known as user equipments (UEs) . In an LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB) . In other examples (e.g., in a next generation, a new radio (NR) , or 5G network) , a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs) , edge nodes (ENs) , radio heads (RHs) , smart radio heads (SRHs) , transmission reception points (TRPs) , etc. ) in communication with a number of central units (CUs) (e.g., central nodes (CNs) , access node controllers (ANCs) , etc. ) , where a set of one or more DUs, in communication with a CU, may define an access node (e.g., which may be referred to as a BS, 5G NB, next generation NodeB (gNB or gNodeB) , transmission reception point (TRP) , etc. ) . A BS or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a BS or DU to a UE) and uplink channels (e.g., for transmissions from a UE to BS or DU) .

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. NR (e.g., new radio or 5G) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR 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 with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) . To these ends, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in NR and LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

BRIEF SUMMARY

The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this disclosure provide advantages that include improved communications between access points and stations in a wireless network.

Certain aspects provide a method for wireless communication by a transmitter. The method generally includes dividing one or more application data units (ADUs) into a first number of source data units (SDUs) , generating a second number of packets based on the first number of SDUs using a Fountain coding scheme wherein the second number is greater than the first number, allocating the second number of packets across multiple radio access technologies (RATs) , and transmitting the second number of packets, to a receiver, via the multiple RATs according to the allocation.

Certain aspects provide a method for wireless communication by a receiver. The method generally includes receiving, via multiple radio access technologies (RATs) , a first number of packets from a transmitter, recovering a second number of source data units (SDUs) by decoding the first number of received packets using a Fountain decoding scheme, and obtaining one or more application data units (ADUs) from the recovered second number of SDUs.

Certain aspects provide means for, apparatus, and/or computer readable medium having computer executable code stored thereon, for performing the techniques described herein.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an example telecommunications system, in accordance with certain aspects of the present disclosure.

FIG. 2 is a block diagram conceptually illustrating a design of an example base station (BS) and user equipment (UE) , in accordance with certain aspects of the present disclosure.

FIG. 3 illustrates a fountain encoding example.

FIG. 4 illustrates a type of fountain encoding.

FIG. 5 illustrates example operations that may be performed by a transmitter, in accordance with certain aspects of the present disclosure.

FIG. 6 illustrates example operations that may be performed by a receiver, in accordance with certain aspects of the present disclosure.

FIG. 7 is a diagram illustrating an example algorithm, in accordance with certain aspects of the present disclosure.

FIGs. 8A &8B illustrates example protocol data unit (PDU) formats, in accordance with certain aspects of the present disclosure.

FIGs. 9A &9B illustrate examples techniques to allocate packets to radio access technologies (RATs) in licensed and unlicensed bands.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation.

DETAILED DESCRIPTION

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for efficiently transmitting data over multiple radio access technologies (RATs) between a transmitter and a receiver, for example, between a base station and a user equipment (UE) .

The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim. 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.

The techniques described herein may be used for various wireless communication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA network may implement a radio technology such as NR (e.g. 5G RA) , Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) .

New Radio (NR) is an emerging wireless communications technology under development in conjunction with the 5G Technology Forum (5GTF) . 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP) . cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

New radio (NR) access (e.g., 5G technology) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g., 25 GHz or beyond) , massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC) . These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe.

Example Wireless Communications System

FIG. 1 illustrates an example wireless communication network 100 in which aspects of the present disclosure may be performed. For example, UEs 120 and/or BS 110 of FIG. 1 may be configured to perform operations described below with reference to FIGs. 5 and 6 to efficiently transmit data over multiple radio access technologies (RATs) .

As illustrated in FIG. 1, the wireless communication network 100 may include a number of base stations (BSs) 110 and other network entities. A BS may be a station that communicates with user equipments (UEs) . Each BS 110 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a NB subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and next generation NodeB (gNB or gNodeB) , NR BS, 5G NB, access point (AP) , or transmission reception point (TRP) may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in wireless communication network 100 through various types of backhaul interfaces, such as a direct physical connection, a wireless connection, a virtual network, or the like using any suitable transport network.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG) , UEs for users in the home, etc. ) . A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in FIG. 1, the

BSs

110a, 110b and 110c may be macro BSs for the

macro cells

102a, 102b and 102c, respectively. The BS 110x may be a pico BS for a pico cell 102x. The BSs 110y and 110z may be femto BSs for the femto cells 102y and 102z, respectively. A BS may support one or multiple (e.g., three) cells.

Wireless communication network 100 may also include relay stations. A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., a BS or a UE) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE or a BS) . A relay station may also be a UE that relays transmissions for other UEs. In the example shown in FIG. 1, a relay station 110r may communicate with the BS 110a and a UE 120r in order to facilitate communication between the BS 110a and the UE 120r. A relay station may also be referred to as a relay BS, a relay, etc.

Wireless communication network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BS, pico BS, femto BS, relays, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless communication network 100. For example, macro BS may have a high transmit power level (e.g., 20 Watts) whereas pico BS, femto BS, and relays may have a lower transmit power level (e.g., 1 Watt) .

Wireless communication network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous operation.

A network controller 130 may couple to a set of BSs and provide coordination and control for these BSs. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with one another (e.g., directly or indirectly) via wireless or wireline backhaul.

The UEs 120 (e.g., 120x, 120y, etc. ) may be dispersed throughout the wireless communication network 100, and each UE may be stationary or mobile. A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE) , a cellular phone, a smart phone, a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc. ) , an entertainment device (e.g., a music device, a video device, a satellite radio, etc. ) , a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered machine-type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

Certain wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system bandwidth. For example, the spacing of the subcarriers may be 15 kHz and the minimum resource allocation (called a “resource block” (RB) ) may be 12 subcarriers (or 180 kHz) . Consequently, the nominal Fast Fourier Transfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 for system bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz) , respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.08 MHz (i.e., 6 resource blocks) , and there may be 1, 2, 4, 8, or 16 subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communications systems, such as NR. NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using TDD. Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication among some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. Base stations are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs) , and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may communicate directly with one another in addition to communicating with a scheduling entity.

In FIG. 1, a solid line with double arrows indicates desired transmissions between a UE and a serving BS, which is a BS designated to serve the UE on the downlink and/or uplink. A finely dashed line with double arrows indicates interfering transmissions between a UE and a BS.

FIG. 2 shows a block diagram illustrating an example base station (BS) and an example user equipment (UE) in accordance with some aspects of the present disclosure.

At the BS 110, a transmit processor 220 may receive data from a data source 212 and control information from a controller/processor 240. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical hybrid ARQ indicator channel (PHICH) , physical downlink control channel (PDCCH) , group common PDCCH (GC PDCCH) , etc. The data may be for the physical downlink shared channel (PDSCH) , etc. The processor 220 may process (for example, encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, such as for the primary synchronization signal (PSS) , secondary synchronization signal (SSS) , and cell-specific reference signal (CRS) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (for example, precoding) on the data symbols, the control symbols, or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232a-232t. Each modulator 232 may process a respective output symbol stream (for example, for OFDM, etc. ) to obtain an output sample stream. Each modulator may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 232a-232t may be transmitted via the antennas 234a-234t, respectively.

At the UE 120, the antennas 252a-252r may receive the downlink signals from the BS 110 and may provide received signals to the demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator 254 may condition (for example, filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (for example, for OFDM, etc. ) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all the demodulators 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (for example, demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at UE 120, a transmit processor 264 may receive and process data (for example, for the physical uplink shared channel (PUSCH) ) from a data source 262 and control information (for example, for the physical uplink control channel (PUCCH) from the controller/processor 280. The transmit processor 264 may also generate reference symbols for a reference signal (for example, for the sounding reference signal (SRS) ) . The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by the demodulators in transceivers 254a-254r (for example, for SC-FDM, etc. ) , and transmitted to the BS 110. At the BS 110, the uplink signals from the UE 120 may be received by the antennas 234, processed by the modulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 120. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller/processor 240.

The

memories

242 and 282 may store data and program codes for BS 110 and UE 120, respectively. A scheduler 244 may schedule UEs for data transmission on the downlink or uplink.

The controller/processor 280 (and/or other processors and modules) at the UE 120 and/or the controller/processor 240 (and/or other processors and modules) of the BS 110 may direct perform or direct the execution of processes for the techniques described herein (e.g., with reference to FIGs. 5 and 6) .

Example Dynamic Scheduling of UE mTRP/Panels

Certain aspects of the present disclosure provide techniques for efficiently transmitting data over multiple radio access technologies (RATs) , for example, between a base station and a user equipment (UE) .

In some cases, the techniques may be used to transfer relatively large amounts of data (e.g., large file transfers or streaming media) . There are various potential issues when attempting to transfer such large amounts of data.

One potential issue is low throughput that can result due to ARQ (Automatic Repeat-reQuest) or Hybrid ARQ (HARQ) as part of radio link control (RLC) in the radio access network (RAN) . Lower throughput may occur when residual errors happen in the HARQ process. The retransmission of packets doubles the resource, at least, and even worse when channel conditions deteriorate.

Low throughput can also occur due to ARQ in the transmission control protocol (TCP) layer in the core network. This can occur while waiting for an ACK in the transmitter. As noted above, retransmission of packets doubles the resource, at least, and even worse when channel conditions deteriorate.

Another potential issue when transmitting large amounts of data is low latency. Low latency can occur, for example, due to re-ordering of packets in the RLC layer in RAN or due to re-ordering of packets in the TCP layer in in the core network. This latency can be relatively high, for example, if the packets at the beginning are received later.

Aspects of the present disclosure provide algorithms utilizing fountain codes for transmissions over multiple RATs that may help address some of the issue described above.

Fountain codes (also known as rateless erasure codes) generally refer to a class of codes with the property that the encoder can generate any number of symbols on-the-fly from the source symbols of a source block of data. The term "Fountain" or "rateless" refers to the fact that these codes do not exhibit a fixed code rate. Luby transform (LT) and Raptor codes are types of Fountain codes. Raptor codes have very efficient linear time encoding and decoding algorithms, and require only a small constant number of XOR operations per generated symbol for both encoding and decoding.

The general principles are that fountain codes generate new packets on the fly for transmission. On the receiver end, several of these symbols combined together may reconstruct the original data (even if some of the symbols are lost/not received successfully) .

FIG. 3 graphically illustrates an example of encoding packets using fountain codes. As illustrated, an original generator matrix G _kj may be used to generate a set of K transmitted packets (p _j) from a sequence of source data (s _k) :

At the receiver end, N packets may be recovered (received) as:

if the following general conditions are met:

G _nk according to received packets is invertible; and

Or the rank of G _nk is K.

Similarly, the general design rule for original generator matrix is that:

G _nk is invertible with minimum N.

As illustrated in FIG. 4, an example raptor code may be constructed using an outer code (e.g., a low density parity check-LDPC code) plus a Luby transform (LT) code. In the illustrated example, 16 source packets are encoded (K = 16) into 20 packets by the outer code. In the illustrated example, 18 packets are received (N=18) by a weak LT code.

In this example, the average degree is 3 (which may be considered relatively low complexity) , meaning three received packets may be used to recover an original source packet. In the illustrated example, the LT code fails to connect with 3 grey packets, but the LT code recovers the other 17 pre-coded packets. The outer code is used to deduce the original packets (an irregular LDPC may be a good option for the outer code) .

The example of FIG. 4 may result in relatively good performance due to the small average degree (of 3) and relatively small number of packets (N = 18) for decoding at the receiver.

Aspects of the present disclosure provide algorithms that may utilizing fountain codes in such a manner for transmissions over multiple RATs that may help address some of the issue described above.

FIG. 5 illustrates example operations 500 that may be performed by a transmitter, in accordance with certain aspects of the present disclosure. For example, operations 500 may be performed by one of the UEs or base stations of FIG. 1 or FIG. 2 to efficiently transmit data to a receiver.

Operations 500 begin, at 502, by dividing one or more application data units (ADUs) into a first number of source data units (SDUs) . At 504, the transmitter generates a second number of packets based on the first number of SDUs using a Fountain coding scheme wherein the second number is greater than the first number. At 506, the transmitter allocating the second number of packets across multiple radio access technologies (RATs) . At 508, the transmitter transmits the second number of packets, to a receiver, via the multiple RATs according to the allocation.

FIG. 6 illustrates example operations 600 that may be performed by a receiver, in accordance with certain aspects of the present disclosure, and may be considered complementary to operations 500 of FIG. 5. For example, operations 600 may be performed by one of the UEs or base stations of FIG. 1 or FIG. 2 to process data transmissions from a transmitter performing operations 500 of FIG. 5.

Operations 600 begin, at 602, by receiving, via multiple radio access technologies (RATs) , a first number of packets from a transmitter. At 604, the receiver recovering a second number of source data units (SDUs) by decoding the first number of received packets using a Fountain decoding scheme. At 606, the receiver obtaining one or more application data units (ADUs) from the recovered second number of SDUs.

FIG. 7 graphically illustrates an encoding algorithm in line with operations 500 described above. As illustrated, one or more application data units (ADUs) may be concatenated (although this step may not be necessary when PDCP PDU size is large) . The ADU may be divided into K source data units (SDUs) , for example, equally or close to equally. The size of SDUs may be predefined and, in some cases, the value of K may be optimized using the SDU size and generator matrix.

Next, encoding using fountain codes may be performed to generate N packets, which may be mapped to N PDUs. The value of N may be determined, for example, by channel conditions.

The transmitter may then allocate N PDUs to multiple RATs. In the illustrated example, four RATs (RAT0-RAT3) are assumed, with M1, M2, M3, and M4 PDUs allocated to RAT0, RAT1, RAT2, and RAT 3, respectively. The actual values of M1, M2, M3, and M4 may be determined by channel condition of each RAT, for example, such that more packets are allocated to a RAT with better channel conditions. Packets may be allocated into the four branches in sequence. The number of packets allocated can be dynamically adjusted, for example, according to channel condition of each RAT.

Parameters of K and size of the SDUs may be predefined and known by both transmitter and receiver (to enable decoding) . There are options for signaling the mother generator matrix. According to a first option, the mother generator matrix itself may be defined and used for/by both the UE and BS. According to a second option, the mother generator matrix may be constructed on the flow (e.g., based on parameters configured by radio resource control –RRC signaling) .

In some cases, the header of generated PDUs may be designed to facilitate ordering at the receiver. FIG. 8A shows one option in which a new header includes an ADU SN (the sequence number-SN of the ADU) and a PDU SN (the sequence number of PDU which is encoded block for fountain codes) .

As illustrated in FIG. 8B, according to a second option, the header of a generated PDU may include a joint encoding of a header including ADU SN and PDU SN, which may help reduce overhead.

There are various potential advantages to the techniques presented herein. One potential advantage is high efficiency. The total size of the receive PDUs may be slightly larger than that of original PDUs. The number of transmit PDUs may also be slightly larger than requirement for decoding. In addition, with the allocation options described above, the better RAT, the better channel conditions are for one RAT, the more data is allocated for transmission on that RAT.

Another potential advantage to the algorithm proposed herein is low latency. There may be no requirement on the ordering of the received subblocks. All the receive subblocks can be used for decoding. Further, the decoding complexity may be relatively low, for example, because of small average row degrees.

The techniques presented herein may be used to allocate packets to different RATs, including one or more RATs operating in a licensed band and one or more RATs operating in an unlicensed band.

Transmissions on unlicensed bands typically utilize a LBT (Listen-Before-Talk) , where the medium is checked and confirmed clear before any transmission. If the LBT mechanism fails, meaning a device wishing to transmit finds the medium busy (e.g., due to a collision with transmission from another device) , that device will wait a random back off duration before attempting to access the medium again. Thus, for unlicensed band, latency and throughput is not typically guaranteed.

Various RATs may be deployed on unlicensed bands. Such RATs include wide area network (3GPP/cellular) RATs, such as Rel-13 License Assisted Access (LAA) , Rel-14 enhanced LAA (eLAA) , Rel-15 further enhanced (feLAA) , and Rel-16 NR-Unlicensed (NR-U) , as well as WLAN/WiFi RATs, such as 802.11 series including WiFi 6.

The techniques described above for transmitting fountain codes can applied to RATs over both licensed band and unlicensed band, for example, in an effort help achieve better performance.

The coded packets of fountain codes can be allocated to different RAT (radio access technologies) in various ways. As noted above, one consider for allocation is based on throughput, such that packets are allocated into the different RATs purely depending on the throughput (more packets may be allocated for a RAT with high throughput) .

As illustrated in FIG. 9A, another option is to consider whether a RAT is in a licensed or unlicensed band. For example, higher priority packets may be allocated to a licensed band to achieve a desired latency or throughput to meet a quality of service (QoS) level. Packets considered as high priority for this purpose may be, for example, packets with degree one (number of one in columns of the generator matrix) , which may be important for a BP (Belief Propagation) decoder to continue. As an alternative, or in addition, packets considered as high priority for this purpose may be packets after K packets, as there may be a high chance that the received packets can be decoded correctly after these packets.

In some cases, as illustrated in FIG. 9B, the coded packets of fountain codes that are allocated to unlicensed band, but are not able to transmit because of an LBT failure, may be forwarded to the licensed band. This may help reduce the latency caused by LBT failure (e.g., avoiding the additional latency incurred due to performing the random back off procedure) .

The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of:a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information) , accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

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 of the 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. ” Unless specifically stated otherwise, the term “some” refers to one or more. 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 under the provisions of 35 U.S.C. §112 (f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for. ”

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components. For example, various operations shown in FIGs. 5 and 6 may be performed by various processors shown in FIG. 2 of the BS 110 and/or UE 120.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device (PLD) , discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user terminal 120 (see FIG. 1) , a user interface (e.g., keypad, display, mouse, joystick, etc. ) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory) , flash memory, ROM (Read Only Memory) , PROM (Programmable Read-Only Memory) , EPROM (Erasable Programmable Read-Only Memory) , EEPROM (Electrically Erasable Programmable Read-Only Memory) , registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared (IR) , radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk, and

disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media) . In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal) . Combinations of the above should also be included within the scope of computer-readable media.

Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For example, instructions for performing the operations described herein and illustrated in FIGs. 5 and 6.

Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc. ) , such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

A method of wireless communication by a transmitter, comprising:

dividing one or more application data units (ADUs) into a first number of source data units (SDUs) ;

generating a second number of packets based on the first number of SDUs using a Fountain coding scheme wherein the second number is greater than the first number;

allocating the second number of packets across multiple radio access technologies (RATs) ; and

transmitting the second number of packets, to a receiver, via the multiple RATs according to the allocation.
The method of claim 1, further comprising concatenating multiple ADUs to obtain the one or more ADUs.
The method of claim 1, wherein the second number is determined, at least in part, based on channel conditions of the multiple RATs.
The method of claim 1, wherein the allocation is based, at least in part, on channel conditions of the multiple RATs.
The method of claim 1, wherein a size of the SDUs is predefined.
The method of claim 5, wherein the first number is optimized based on the size of the SDUs and a matrix used to generate the second number of packets.
The method of claim 6, wherein the matrix is known at both the transmitter and the receiver.
The method of claim 6, wherein the matrix is generated by at least one of the transmitter or the receiver based on one or more parameters configured via radio resource control (RRC) signaling.
The method of claim 1, wherein each packet has a header that includes an ADU sequence number and a sequence number of a protocol data unit (PDU) that is encoded block for Fountain codes.
The method of claim 1, wherein each packet has a header that includes a field with a jointly coded ADU and PDU sequence number.
The method of claim 1, wherein the multiple RATs comprise:

at least one RAT operating in an unlicensed band; and

at least one RAT operating in a licensed band.
The method of claim 11, wherein allocating the second number of packets across the multiple RATs comprises allocating packets considered high priority to at least one RAT operating in the licensed band.
The method of claim 11, further comprising:

performing a listen before talk (LBT) before transmitting at least one packet allocated for transmission on a RAT operating in the unlicensed band; and

if the LBT fails, forwarding that packet for transmission on a RAT operating in the licensed band.
A method of wireless communication by a receiver, comprising:

receiving, via multiple radio access technologies (RATs) , a first number of packets from a transmitter;

recovering a second number of source data units (SDUs) by decoding the first number of received packets using a Fountain decoding scheme; and

obtaining one or more application data units (ADUs) from the recovered second number of SDUs.
The method of claim 14, further comprising extracting multiple ADUs from the one or more ADUs.
The method of claim 14, wherein a number of packets received on each RAT is based, at least in part, on channel conditions of the multiple RATs.
The method of claim 14, wherein a size of the SDUs is predefined.
The method of claim 17, wherein the second number is optimized based on the size of the SDUs and a matrix used to generate the second number of packets.
The method of claim 18, wherein the matrix is known at both the transmitter and the receiver.
The method of claim 19, wherein the matrix is generated by at least one of the transmitter or a targeted receiver of the packets based on one or more parameters configured via radio resource control (RRC) signaling.
The method of claim 14, wherein:

each packet has a header that includes an ADU sequence number and a sequence number of a protocol data unit (PDU) that is encoded block for Fountain codes; and

the receiver orders the PDUs and ADUs based on the ADU and PDU sequence numbers.
The method of claim 14, wherein:

each packet has a header that includes a field with a jointly coded ADU and PDU sequence number; and

the receiver orders the PDUs and ADUs based on the jointly coded ADU and PDU sequence numbers.
The method of claim 14, wherein the multiple RATs comprise:

at least one RAT operating in an unlicensed band; and

at least one RAT operating in a licensed band.
An application for wireless communication by a transmitter, comprising:

means for dividing one or more application data units (ADUs) into a first number of source data units (SDUs) ;

means for generating a second number of packets based on the first number of SDUs using a Fountain coding scheme wherein the second number is greater than the first number;

means for allocating the second number of packets across multiple radio access technologies (RATs) ; and

means for transmitting the second number of packets, to a receiver, via the multiple RATs according to the allocation.
An apparatus for wireless communication by a receiver, comprising:

means for receiving, via multiple radio access technologies (RATs) , a first number of packets from a transmitter;

means for recovering a second number of source data units (SDUs) by decoding the first number of received packets using a Fountain decoding scheme; and

means for obtaining one or more application data units (ADUs) from the recovered second number of SDUs.
An application for wireless communication by a transmitter, comprising:

at least one processor configured to

divide one or more application data units (ADUs) into a first number of source data units (SDUs) ,

generate a second number of packets based on the first number of SDUs using a Fountain coding scheme wherein the second number is greater than the first number, and

allocate the second number of packets across multiple radio access technologies (RATs) ; and

a transmitter configured to transmit the second number of packets, to a receiver, via the multiple RATs according to the allocation.
An apparatus for wireless communication by a receiver, comprising:

a receiver configured to receive, via multiple radio access technologies (RATs) , a first number of packets from a transmitter; and

at least one processor configured to

recover a second number of source data units (SDUs) by decoding the first number of received packets using a Fountain decoding scheme, and

obtain one or more application data units (ADUs) from the recovered second number of SDUs.