WO2020062044A1

WO2020062044A1 - Advanced v2x communication mechanism

Info

Publication number: WO2020062044A1
Application number: PCT/CN2018/108378
Authority: WO
Inventors: Tao Chen; Feifei Zhang
Original assignee: Mediatek Singapore Pte. Ltd.
Priority date: 2018-09-28
Filing date: 2018-09-28
Publication date: 2020-04-02

Abstract

This disclosure relates generally to wireless communications, and, more particularly, to methods and apparatus for the establishment and HARQ transmission of V2X communications. To support efficient HARQ retransmission in sidelink (SL) unicast/groupcast communication, the hybrid retransmission can be supported by selecting BS or V2X Tx UE or both to perform retransmission for SL communication depending on the received A/N information and the channel condition. Moreover, for acquisition of the timing information with varying numerologies, the slot index information associated with the default numerology or indicated numerology can be provided by the signaling or the reference signal (e. g., SL PSS/SSS/PBCH-DMRS/PBCH payload). In case of FDD UL (or any paired frequencies) indicated for V2X communication, the corresponding (DL) frequency should be provided by signaling or a pre-defined table for UE searching the corresponding BS, e.g., for synchronization purpose. Further, in case of multiple sync sources, the sync source priority information can be carried in PSS/SSS/PBCH-DMRS for early determination without SL MIB decoding. Moreover, the special handling, e. g., by arranging such information bits in the special position during polar encoding can improve the reliability and speedup the early decoding without full decoding of SL MIB. The ID for identifying the SL unicast/groupcast/broadcast communication can be determined based on the scenario (e.g., in-coverage, out-of-coverage with configuration signaling, out-of-coverage with only pre-configured information).

Description

ADVANCED V2X COMMUNICATION MECHANISM

TECHNICAL FIELD

This disclosure relates generally to wireless communications, and, more particularly, to methods and apparatus for the establishment and HARQ transmission of V2X communications.

BACKGROUND

In 5G new radio, V2X sidelink (SL) communication may be supported by the unicast, groupcast and broadcast communications. However, there are several issues to be addressed such as how to perform HARQ for unicast/groupcast transmission and how to search and establish the sidelink (SL) for V2X communication.

SUMMARY

To support efficient HARQ retransmission in sidelink (SL) unicast/groupcast communication, the hybrid retransmission can be supported by selecting BS or V2X Tx UE or both to perform retransmission for SL communication depending on the received A/N information and the channel condition. Moreover, for acquisition of the timing information with varying numerologies, the slot index information associated with the default numerology or indicated numerology can be provided by the signaling or the reference signal (e.g., SL PSS/SSS/PBCH-DMRS/PBCH payload) . In case of FDD UL (or any paired frequencies) indicated for V2X communication, the corresponding (DL) frequency should be provided by signaling or a pre-defined table for UE searching the corresponding BS, e.g., for synchronization purpose. Further, in case of multiple sync sources, the sync source priority information can be carried in PSS/SSS/PBCH-DMRS for early determination without SL MIB decoding. Moreover, the special handling, e.g., by arranging such information bits in the special position during polar encoding can improve the reliability and speedup the early decoding without full decoding of SL MIB. The ID for identifying the SL unicast/groupcast/broadcast communication can be determined based on the scenario (e.g., in-coverage, out-of-coverage with configuration signaling, out-of-coverage with only pre-configured information) .

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1a shows the procedure for SL data retransmission performed by V2X Tx UE following SL grant from gNB.

FIG. 1b shows the procedure for SL data retransmission performed by gNB directly.

FIG. 2 shows an exemplary block diagram of a UE 800 according to an embodiment of the disclosure.

DETAILED DESCRIPTION OF PREFERRED IMPLEMENTATIONS

Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to ... " . Also, the term "couple" is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. The making and using of the embodiments of the disclosure are discussed in detail below. It should be appreciated, however, that the embodiments can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative, and do not limit the scope of the disclosure. Some variations of the embodiments are described. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements.

The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. Note that the 3GPP specifications described herein are used to teach the spirit of the invention, and the invention is not limited thereto.

As shown in Figure 1a, it illustrates the procedure for SL data retransmission performed by Tx UE with control from gNB with the following steps:

Step 1: Tx (and Rx) UE (s) receives the DL grant from base station with scheduling information for the first SL data transmission (and the corresponding A/N resources for HARQ feedback) .

Step 2: Tx UE performs the 1st data transmission to Rx UE. Due to the broadcast property and known information at BS for decoding so that BS can also receive the SL data correctly with proper channel condition and power control in SL (potentially controlled by BS) .

Step 3. Rx UE may provide NACK to Tx UE in case of failure of data reception. Similarly, BS may receive such feedback information as well due to know information for detection at BS.

Step 4. BS may send SL grant for SL data retransmission, . e.g, if it is NACK and BS also fails for SL data reception.

Step 5. Tx UE perform the SL data retransmission following the SL grant from BS. BS can still receive the data similar to reception at BS in step 2.

Step 6. Rx UE may send ACK if received correctly. It can also be received by BS similar to reception at BS in step 3.

Alternatively, as shown in Figure 1b, it illustrates the procedure for SL data retransmission performed by BS directly as the following steps (with main difference starting from step 4) :

Step 4. BS may perform SL data retransmission in uu link to Rx UE (s) directly, . e.g, if it is NACK and BS has received the SL data correctly.

Step 5. Rx UE may send ACK in uu link rather than sidelink corresponding to the retransmission from BS.

As shown in Figure 1a and 1b, the retransmission for SL unicast/groupcast data transmission can be done either by V2X Tx UE or gNB (or even both) . To support efficient HARQ retransmission in sidelink (SL) unicast/groupcast communication, the hybrid retransmission can be supported by selecting BS or V2X Tx UE (or both) to perform HARQ retransmission for SL communication depending on the received A/N information and the channel condition.

To enable the adaptive retransmission, the power control for A/N should be done based on the pathloss of the worst one between uu link and SL link, so that both base station and Tx UE can receive the A/N correctly. However, considering the potential interference to the base station in the uu link in case of licensed shared band, the power control can be based on the pathloss capped by the uu link. Therefore, the independent PC for SL and uu link will be needed and controlled by DCI with separated RNTI for differentiation. However, as the restriction, the SL Power can not be higher than the cellular link if needed. Such restriction can be either indicated to UE by signaling or just controlled by gNB.

Besides, BS may need to buffer the received side link data and perform retransmission correctly, i.e., a set of soft buffer for sidelink data reception/combining at BS may be needed in addition to the soft buffer for the cellular link.

Whether to perform the adaptive HARQ retransmission can further depend on the channel condition, e.g., CSI and/or pathloss in SL and uu links. Then gNB can make the decision according to the CSI/Pathloss and ACK information to determine whether to perform retransmission in SL or uu link. If SL retransmission is selected, the SL grant will be sent to schedule the retransmission resources and the time/frequency resources for the corresponding A/N. If uu link is selected for retransmission, the DCI in DL grant will be sent to schedule the retransmission resources and the time/frequency resources for the corresponding A/N.

For SL grant from gNB, it can be received by both Tx and Rx UEs simultaneously based on a common ID (RNTI or L1-ID) scrambled in CRC. The number of time/frequency resources for SL grant is selected based on the worst one between the Tx UE uu link (s) and Rx UE uulink (s) . Accordingly, there may not be the PSCCH associated to SL data transmission, if all scheduling information have been provided in the SL grant by gNB to both Tx and Rx UEs.

Further, Rx UE may also transmit the data back with PSSCH. In this case, A/N can be piggyback to Tx UE in PSSCH of Rx UE with data for transmission.

The SL scheduling request can also be carried in PSSCH by Rx UE to indicate the data in the buffer. Further, the buffer status information can be carried in PSSCH or MAC-CE later.

In PSSCH, the Tx UE or a mater UE selected by gNB can further assign the SL time resource for Tx/Rx between UEs according to the SI request and buffer status information and traffic type (e.g., unicast, groupcast or broadcast) received from Rx UE (s) . So the SL PSSCH (from the master UE) may carry Tx/Rx configuration information within a period or just Tx/Rx indication for the next time unit (e.g., slot) for the Rx UEs (within a cluster) .

Moreover, for acquisition of the timing information with varying numerologies, the slot index information associated with the default numerology or indicated numerology can be provided by the signaling or the reference signal (e.g., SL PSS/SSS/PBCH-DMRS/PBCH payload) . For example, slot index within a subframe (e.g., 1ms) can be indicated in addition to the SFN and subframe index. The number of bits for slot index indication may depend on the detected SL PBCH numerology or a default numerology (e.g., band specific and pre-defined in a table) or the numerology indicated by BS associated to the frequency layer (s) , e.g., 1 bit for 15khz and 2 bits for 30khz and 4 bits for 60khz. Moreover, in case of SSS or PBCH DMRS for carrying such information, the different sequences can be selected or initialized to indicate the slot index number. In addition, the slot index and subframe information can be indicated together as one field rather than two fields.

In case of FDD UL frequency (or any paired frequencies) configured for V2X communication, the corresponding (DL) frequency (e.g., ARFCN) and/or band information (band indicator) may need to be provided by signaling or pre-defined in a table for UE searching the corresponding BS, e.g., for synchronization purpose.

In case of multiple sync sources and sync types, the sync source priority information (e.g., Priority group 1 is for UEs with direct sync to GNSS/BS and Priority group 2 is for UEs with indirect sync to GNSS/BS) can be carried in PSS/SSS/PBCH-DMRS for early determination of the priority for reception without SL PBCH decoding. Moreover, the special handling, e.g., by arranging such information bits in the special position (some more reliable and early detected positions) during polar encoding can improve the reliability and speed up the early decoding without full decoding of SL MIB.

The ID for identifying the SL unicast/groupcast/broadcast communication can be determined based on the scenario (e.g., in-coverage, out-of-coverage with configuration signaling, out-of-coverage with only pre-configured information) . Such ID may be scrambled together w/wo Cell ID depending on the scenario. For example, in case of out-of-coverage without serving cell, the ID is enough. In case of in-coverage or out-of-coverage with serving cells, the ID together with cell ID can be used for scrambling and identification. Alternatively, the ID can be configured by the BS as scrambling ID. Such scrambling ID will be given by gNB during SL connection setup so that it can be known by the involved Tx/Rx UEs for unicast/groupcast communication.

Fig. 2 shows an exemplary block diagram of a UE 800 according to an embodiment of the disclosure. The UE 800 can be configured to implement various embodiments of the disclosure described herein. The UE 800 can include a processor 810, a memory 820, and a radio frequency (RF) module 830 that are coupled together as shown in Fig. 2. In different examples, the UE 800 can be a mobile phone, a tablet computer, a desktop computer, a vehicle carried device, and the like.

The processor 810 can be configured to perform various functions of the UE 120 described above with reference to Figs. 1a-1b. The processor 810 can include signal processing circuitry to process received or to be transmitted data according to communication protocols specified in, for example, LTE and NR standards. Additionally, the processor 810 may execute program instructions, for example, stored in the memory 820, to perform functions related with different communication protocols. The processor 810 can be implemented with suitable hardware, software, or a combination thereof. For example, the processor 810 can be implemented with application specific integrated circuits (ASIC) , field programmable gate arrays (FPGA) , and the like, that includes circuitry. The circuitry can be configured to perform various functions of the processor 810.

In one example, the memory 820 can store program instructions that, when executed by the processor 810, cause the processor 810 to perform various functions as described herein. The memory 820 can include a read only memory (ROM) , a random access memory (RAM) , a flash memory, a solid state memory, a hard disk drive, and the like.

The RF module 830 can be configured to receive a digital signal from the processor 810 and accordingly transmit a signal to a base station in a wireless communication network via an antenna 840. In addition, the RF module 830 can be configured to receive a wireless signal from a base station and accordingly generate a digital signal which is provided to the processor 810. The RF module 830 can include digital to analog/analog to digital converters (DAC/ADC) , frequency down/up converters, filters, and amplifiers for reception and transmission operations. For example, the RF module 830 can include converter circuits, filter circuits, amplification circuits, and the like, for processing signals on different carriers or bandwidth parts.

The UE 800 can optionally include other components, such as input and output devices, additional CPU or signal processing circuitry, and the like. Accordingly, the UE 800 may be capable of performing other additional functions, such as executing application programs, and processing alternative communication protocols.

The processes and functions described herein can be implemented as a computer program which, when executed by one or more processors, can cause the one or more processors to perform the respective processes and functions. The computer program may be stored or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with, or as part of, other hardware. The computer program may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. For example, the computer program can be obtained and loaded into an apparatus, including obtaining the computer program through physical medium or distributed system, including, for example, from a server connected to the Internet.

The computer program may be accessible from a computer-readable medium providing program instructions for use by or in connection with a computer or any instruction execution system. A computer readable medium may include any apparatus that stores, communicates, propagates, or transports the computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable medium can be magnetic, optical, electronic, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. The computer-readable medium may include a computer-readable non-transitory storage medium such as a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM) , a read-only memory (ROM) , a magnetic disk and an optical disk, and the like. The computer-readable non-transitory storage medium can include all types of computer readable medium, including magnetic storage medium, optical storage medium, flash medium and solid state storage medium.

While aspects of the present disclosure have been described in conjunction with the specific embodiments thereof that are proposed as examples, alternatives, modifications, and variations to the examples may be made. Accordingly, embodiments as set forth herein are intended to be illustrative and not limiting. There are changes that may be made without departing from the scope of the claims set forth below.

Claims

A method, comprising:

receiving a configuration for SL setup and data retransmission;

performing SL setup and data transmission; and

performing data retransmission adaptively from gNB and/or UE according to the received HARQ feedback and channel conditions for SL (re-) transmission.
The method of claim 1, wherein a configuration for SL setup is defined by SL PBCH carrying SFN/subframe/slot information based on a detected or default or configured numerology.
The method of claim 1, wherein a configuration for SL setup is defined by a DL frequency information case of FDD UL frequency (or any paired frequencies) configured for V2X communication.
The method of claim 1, wherein a configuration for SL setup is defined by sync source priority information provided by PSS/SSS/PBCH-DMRS and/or special location in polar coding bits.
The method of claim 1, wherein a configuration for SL setup is defined by ID for differentiation between unicast/groupcast/broadcast between UEs in scrambling.
The method of claim 1, wherein data retransmission adaptively from gNB and/or UE according to the received HARQ feedback for SL (re-) transmission can be done by adaptively selecting BS or UE to perform HARQ retransmission depending on the channel condition, e.g., CSI and/or pathloss in SL and uu links.
The method of claim 1, wherein data retransmission adaptively from gNB and/or UE according to the received HARQ feedback for SL (re-) transmission can be done by carrying all scheduling information for SL in DCI for Tx/Rx UEs to skip SL PSCCH transmission.
The method of claim 1, wherein data retransmission adaptively from gNB and/or UE according to the received HARQ feedback for SL (re-) transmission can be done by sending SI, buffer status information, traffic type in SL to a master UE to control and schedule the resource in SL.
The method of claim 1, wherein data retransmission adaptively from gNB and/or UE according to the received HARQ feedback for SL (re-) transmission can be done by indicating Tx/Rx resources in SL PSSCH by a master/Tx UE to coordinate the resources between UEs.