WO2020199211A1

WO2020199211A1 - 2-stage sci for v2x communication

Info

Publication number: WO2020199211A1
Application number: PCT/CN2019/081565
Authority: WO
Inventors: Tao Chen; Zhixun Tang; Chien-Yi Wang; Pei-Kai Liao; Min LEI
Original assignee: Mediatek Singapore Pte. Ltd.
Priority date: 2019-04-03
Filing date: 2019-04-04
Publication date: 2020-10-08
Also published as: CN112314006A; CN112314006B

Abstract

For V2X sidelink communication, the sidelink physical data channel (PSSCH) can be scheduled by sidlelink control information (SCI) carried in sidelink physical control channel (PSCCH). 2-stage SCI can be used by applying the 1 ^st SCI for the purpose of sensing and broadcast communication whereas the 2 ^nd SCI carrying the remaining information for data scheduling of unicast/groupcast data transmission. The 2 ^nd SCI time/frequency location can be derived from the information fields carried in the 1 ^st SCI. Both 1 ^st and 2 ^nd SCIs can be transmitted using the centralized frequency resources or distributed frequency resources. The 1 ^st SCI and 2 ^nd SCI can be time domain multiplexed in different symbols and/or frequency domain multiplexed in different RBs (interleaved or non-interleaved). The 2 ^nd SCI can have the link adaptation associated with the data channel link adaptation. 2 ^nd SCI can have the same transmission scheme as the data channel with the same antenna port (s) or the different transmission scheme with different antenna port (s) but with the same power per resource element. Furthermore, power boosting can be applied between the sidelink control channel and data channel. The power offset can be indicated during the sidelink RRC connection setup for unicast/groupcast communication or indicated in the 1 ^st SCI. DMRS location in frequency domain for the 1 ^st SCI can be fixed. The reference signal for 2 ^nd SCI decoding can reuse/share the data channel (PSSCH) DMRS wholly or partly with no need of the dedicated DMRS to reduce the overhead. The dest (or source) UE/group ID can be used for sequence generation of the data channel (and 2 ^nd SCI) DMRS. The 2 ^nd SCI can use the polar coding but share the time/frequency resources as the data channel. The shorter CRC (e. g, 16 bits CRC) can be applied for the 2 ^nd SCI (and/or 1 ^st SCI) to reduce the CRC overhead. It can be indicated in the 1 ^st SCI whether the DMRS between 1 ^st SCI and 2 ^nd SCI/Data DMRS are QCL' ed or whether the same transmission scheme is used based on the same antenna port (s). Then the channel estimation for 2 ^nd SCI/Data can use 1 ^st SCI DMRS or not depending on the indication.

Description

2-STAGE SCI FOR V2X COMMUNICATION

FIELD OF INVENTION

This disclosure relates generally to wireless communications, and, more particularly, to methods and apparatus for the 2-stage control channel design for V2X communications.

BACKGROUND OF THE INVENTION

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 for control channels considering the complexity, channel sensing and flexibility.

SUMMARY OF THE INVENTION

For V2X sidelink communication, the sidelink physical data channel (PSSCH) can be scheduled by sidlelink control information (SCI) carried in sidelink physical control channel (PSCCH) . 2-stage SCI can be used by applying the 1st SCI for the purpose of sensing and broadcast communication whereas the 2nd SCI carrying the remaining information for data scheduling of unicast/groupcast data transmission.

The 2nd SCI time/frequency location can be derived from the information fields carried in the 1st SCI. Both 1st and 2nd SCIs can be transmitted using the centralized frequency resources or distributed frequency resources. The 1st SCI and 2nd SCI can be time domain multiplexed in different symbols and/or frequency domain multiplexed in different RBs (interleaved or non-interleaved) . The 2 ^nd SCI can share/use the time/frequency resources reserved for the data channel.

The 2nd SCI can have the link adaptation associated with the data channel link adaptation. 2nd SCI can have the same transmission scheme as the data channel with the same antenna port (s) or the different transmission scheme with different antenna port (s) but with the same power per resource element.

For power setting, power boosting can be applied between the sidelink control channel and data channel. The power offset can be indicated during the sidelink RRC connection setup for unicast/groupcast communication or indicated in the 1st SCI.

DMRS location in frequency domain for the 1st SCI can be fixed. The reference signal for 1 ^st and/or 2nd SCI can reuse/share the data channel (PSSCH) DMRS wholly or partly with no need of the dedicated DMRS for 2 ^nd SCI to reduce the overhead. The dest (or source) UE/group ID can be used for sequence generation of the data channel (and 2nd SCI) DMRS. Alternatively, the reference signal for 1 ^st and/or 2nd SCI can have the own dedicated DMRS than data DMRS. It is possible to do the channel estimation for 1 ^st and/or 2 ^nd SCI based on the dedicated DMRS independently or jointly with data DMRS if the antenna port and/or transmission scheme is same for data and control channel.

The 2nd SCI can use the polar coding. The shorter CRC (e.g, 16 bits CRC) can be applied for the 2nd SCI (and/or 1st SCI) to reduce the CRC overhead.

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. 1 shows TD multiplexing between 1 ^st SCI and 2 ^nd SCI.

FIG. 2 shows FDM multiplexing between 1 ^st SCI and 2 ^nd SCI.

FIG. 3 shows an exemplary design for localized resource allocation.

FIG. 4 shows an exemplary design for distributed resource allocation.

FIG. 5 shows an exemplary block diagram of a UE (a. k. adevice) according to an embodiment of the disclosure.

DETAILED DESCRIPTION

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 one embodiment, the 1 ^st SCI and 2 ^nd SCI (vs. single SCI) are comprising one or multiple fields as listed in the table 1 as below.

- “Format indicator” can be 1 or more bits information to indicate whether it is 1 ^st SCI for scheduling broadcast message and/or 1 ^st SCI used at least for sensing purpose. If it is used to schedule broadcast transmission, then there is no need of 2 ^nd SCI to be followed. If it is used for sensing purpose (e.g., for unicast/groupcast) , the 2 ^nd SCI will be followed to carry the remaining information such as scheduling information for unicast/groupcast message reception. Moreover, 1 ^st SCI can also be used to carry the sensing information for the grant-free transmission (RRC-based grant-free transmission similar to type 1 grant-free transmission in uu interface or SCI-based grant-free transmission similar to SPS transmission or type 2 grant-free transmission in uu interference) . In this case, the 2 ^nd SCI may not be needed since the detailed scheduling information has been carried in the configuration message by the setup or (pre-) configuration. In particular, such 1 ^st SCI for sensing purpose of the grant-free transmission can be transmitted periodically based on (pre-)configuration or transmitted based on sensing results along with each data transmission. It can be transmitted together with data or earlier than the data transmission for the sensing purpose. Moreover, the format indicator can further indicate whether there is only 1 ^st SCI transmission for sensing purpose without any 2 ^nd SCI for scheduling information and scheduling information for Data. For example, for grant-free transmission, the target UE has already known the scheduling information for data based on (pre-)configuration or UE-UE signaling. Then the 1 ^st SCI is just for sensing purpose to be decoded by the other UEs but not by the intended UE. In this case, there is no need of 2 ^nd SCI and also at least no need of MCS information in the 1 ^st SCI.

- “Source/Dest UE/group ID (s) ” can be 8/16/24bits. For broadcast message or communication, there may be no need of source/Dest UE/group ID. Meanwhile, the synchronous HARQ is applied for broadcast transmission by indicating the retransmission time via the field “Time gap between initial transmission and retransmission” . For unicast/groupcast, “Time gap between initial transmission and retransmission” may not be needed because of asynchronous HARQ. Dest UE/group ID can be included in the first SCI to indicate the intended UE (s) for 2 ^nd SCI and data reception so that the unintended UE (s) do not need to receive the 2 ^nd SCI and the associated data. Meanwhile, the Dest UE/group ID can be used for the DMRS sequence generation, e.g., the initial value for sequence generation can be a function of the Dest UE/group ID. In case of grant-free transmission, the source/dest group/UE ID may not be included in 1 ^st SCI (maybe no need of 2 ^nd SCI in this case) because it is just for sensing purpose to be decoded by the other UEs. The scheduling information for grant-free transmission (at least the first transmission) has been (pre-) configured with no need of SCI transmission. Alternatively, the dest ID can be included in 1 ^st SCI for sensing of the grant-free transmission, which provides the potential for proactive interference cancellation by reusing the same time/frequency resources for the other UEs as the dest UE to exploit the spatial reuse gain via IC.

- “Priority” is used to indicate the priority of the transmission to be used for sensing and resource selection, similar to the usage in LTE V2X.

- “Resource reservation” is used to indicate/derive time resources to be used for the upcoming transmission (s) .

- “Frequency resource location” can be used to indicate the frequency domain resource allocation for the data (including 2 ^nd SCI) transmission or the frequency shift to the lowest index of the physical resource blocks (or subchannel) for the last data transmission.

- “Time gap between initial transmission and retransmission” is mainly used to derive the occasions of the retransmission or the corresponding initial transmission. In case of asynchronous HARQ for unicast/groupcast, it may not be needed.

- “Retransmission index” is used to indicate the first transmission or retransmission.

- “Modulation and coding scheme” may be used to indicate the MCS level of the broadcast communication. In case of unicast/groupcast with 2-stage SCI transmission, the exact MCS information can be carried in the 2 ^nd SCI. alternatively or additionally, only one or a few modulation levels (such as QPSK, 16QAM, 64QAM, 256QAM) can be indicated in the 1 ^st SCI for deriving the target SINR level for data transmission and the potential resource size of the 2 ^nd SCI.

- “Transmission format” can be used to indicate whether TB scaling is applied or which MCS table is used (Table with up to 64QAM or Table with up to 256QAM) associated with the interpretation of the MCS field.

- “New data indicator” indicates whether it is a new transmission or retransmission.

- “Redundancy version” indicates the RV version of the transmission.

- “HARQ process number” indicates the number of HARQ process to be used for HARQ combining.

- “A-CSI request” requests the UE to measure and report aperiodical CSI. The CSI to be measured can be the DMRS of the first SCI, 2 ^nd SCI and/or Data DMRS which are occurred at the same slot of the corresponding SCI transmission.

- “DMRS TDM Pattern” indicates the number and the locations of the Data DMRS in time domain. The starting symbol for data DMRS can be indicated by another filed or (pre-) configured by the network, SL connection setup message, or UE. For example, the starting symbol for data DMRS is always in the first symbol of the slot or the first symbol for SL transmission in a slot, or the first symbol for SL Data transmission or the first symbol just after the 1 ^st SCI transmission.

- “2nd SCI T/F location” indicates the time/frequency locations of the 2 ^nd SCI. more details can refer to the sections below.

- “Reserved Bits” may be for the future usage or to be decided later.

- “CRC” field is used to carry CRC bits. It can be further scrambled by UE/group ID (dest and/or source UE/group ID) . CRC bits can be 8, 16, or 24 bits. In case of 24 bits of CRC and 24 bits ID, all 24 bits can be scrambled in the CRC of the 2 ^nd SCI. alternatively, only (the most or the least) 16 bits of ID can be scrambled in the end of 16bits CRC of the 24bits CRC. The remaining 8 bits of ID can be explicitly carried in the payload of 2 ^nd SCI. the similar approach can be applied for the case with 16 bits CRC and 16 bits of UE ID.

- Additionally, the following information can be carried:

- The port number information and the ports.

- The field for the different size of the 2 ^nd SCI. For example, 2 bits can be used to indicate one of four different sizes which are pre-defined in a table. According to the different SCI size, the time/frequency location for 2 ^nd SCI as indicated by “2nd SCI T/F location” can be interpreted differently.

- The field to indicate the starting symbol of the 1 ^st SCI, 2 ^nd SCI and/or data transmission.

- The field to indicate the lowest PRB index of the 1 ^st SCI, 2 ^nd SCI and/or data transmission.

Table 1. Potential fields to be included in 1 ^st SCI, 2 ^nd SCI and Single SCI.

As one embodiment, the 2nd SCI time/frequency location can be derived from the information fields carried in the 1st SCI. Both 1st and 2nd SCIs can be transmitted using the centralized frequency resources or distributed frequency resources. The 1st SCI and 2nd SCI can be time domain multiplexed in different symbols and/or frequency domain multiplexed in different RBs (interleaved or non-interleaved) . The 2 ^nd SCI can share/use the time/frequency resources reserved for the data channel.

As shown in Figure 1, the 1 ^st SCI and 2 ^nd SCI are TDM multiplexed. Alternatively or additionally, multiple symbols can be applied to 1 ^st SCI and 2 ^nd SCI separately.

As shown in Figure 2, the 1 ^st SCI and 2 ^nd SCI are FDM multiplexed. Alternatively or additionally, multiple symbols can be applied to 1 ^st SCI and 2 ^nd SCI separately.

As one embodiment, the 2 ^nd SCI location can be indicated in the 1 ^st SCI explicitly using 2～4 bits. Each codepoint (or entry) can indicate one of the time/frequency locations of 2 ^nd SCI predefined as a table.

As one embodiment, the 2 ^nd SCI location can be derived based on the field in the first SCI which is used to indicate the modulation level, a subset of modulations, or the MSB/LSB bits of the MCS index in a MCS table for data transmission as shown in Table 2. In this case, the modulation to be used for the data can determine the target SINR level. Supposing the payload size are fixed for the 2 ^nd SCI, the resource size for 2 ^nd SCI (e.g., total number of PRBs) can be a function of the modulation level for data transmission due to the link adaption together with data transmission. That is, the resource size is derived from the data modulation level which is linked to a target SINR/SNR level. Such target SINR/SNR level can be used to determine the coding rate. Then the resource size can be determined according to the coding rate and the payload size. Further, the corresponding time/frequency locations of each resource or resource size (e.g., the number of symbols in time domain and the number of PRBs in frequency domain) can be derived based on the pre-defined rules and the (pre-) configurations, e.g., the (pre-) configuration of the starting symbol and/or the lowest index of the PRBs for 2 ^nd SCI or the (pre-) configuration relative/fixed offset in time/frequency domain to the data resource allocation. In case of multiple combinations of time and frequency resources, it can be determined based on the data resource configuration. For example, the bandwidth for 2 ^nd SCI is selected from a set of values with the one close to the data or subchannel bandwidth. For example, with a set of values {12, 24, 48, 96} RBs for 2 ^nd SCI bandwidth and the data transmission bandwidth is indicated as 50 RBs, the 2 ^nd SCI bandwidth will be selected as 48 RBs, i.e., close but smaller than data bandwidth. Furthermore, a PRB_Offset can be applied as the restriction, e.g., close but smaller than Data BW_PRB –PRB_Offset. Such PRB_Offset can be used to leave PRB_Offset/2 PRBs in each edge of the bandwidth and protect 2 ^nd SCI from in-band emission interference. Such PRB_Offset can be (pre-) configured by base station or UEs. Further based on the selected bandwidth and the total number of resource size, the number of symbols in time domain can be determined accordingly as such:

Number of symbols = floor (the total number of RBs/Number of RBs per symbol) or ceiling (the total number of RBs/Number of RBs per symbol)

Table 2. Mapping between data modulation level and resource (size) or 2 ^nd SCI

Table 3. Determination of Data MCS base on combination of the fields in the 1 ^st SCI and 2 ^nd SCI.

Table 4: Modulation, TBS index and redundancy version table for SL data channel

Alternatively, a new MCS table can be constructed as Table 5 by using the combination of the fields in 1 ^st SCI and 2 ^nd SCI to derive the final data MCS. Such solution can reduce the signaling overhead by indicating the resource (size) for 2 ^nd SCI and part of MCS information for data transmission simultaneously.

Table 5: Modulation, TBS index and redundancy version table for SL data channel based on combination of fields in 1 ^st SCI and 2 ^nd SCi.

Similarly, if the MCS index range is used instead of modulation level, the resource (size) for 2 ^nd SCi can be derived in the similar rule as shown in table 6.

Table 6. Mapping between MCS index range and resource (size) or 2 ^nd SCI

In case of MIMO transmission, the port information (the number of ports and/or the ports) can be carried in the 1 ^st SCI. in case of the different layers (or different number of ports) for (2 ^nd SCI) transmission, the corresponding resource (size) can be different. So the number of ports can be further used to determine the 2 ^nd SCI resources. For example, the 2 ^nd SCI resource (size) is a function of number of ports or ports. More layers, the smaller size per layer for 2 ^nd SCI due to multiple layer transmissions.

The 2nd SCI can have the link adaptation associated with the data channel link adaptation. 2nd SCI can have the same transmission scheme as the data channel with the same antenna port (s) or the different transmission scheme with different antenna port (s) but with the same power per resource element. If the 1 ^st SCI can have the link adaption with several resource (sizes) or aggregation levels as NR/LTE control channels, the 2 ^nd SCI resource (size) can also be implicitly indicated or derived based on the detection of the 1 ^st SCI resources. For example, the 2 ^nd SCI resource (size) is a function of the detected 1 ^st SCI resource size or based on a pre-defined table with a mapping between 2 ^nd SCI resource (size) and the detect 1 ^st SCI resource (size) .

For 1 ^st /2 ^nd SCI or single SCI resource allocation, both localized and distributed resource allocation can be supported. The total number of RBs required for sidelink control channel can be calculated as below:

Total_SCI_RBs = Total_Control_REs/available_CtrlREinOneRB = (Payload+CRCbits) /targetCodingRate/ (REs_inOneRB –DMRSorOtherREs_inOneRB)

Wherein,

targetCodingRate can be determined by the target SNR level which can be derived from the field in 1 ^st SCI (e.g., data modulation level or MCS range) for control channel with link adaption. For the control channel without link adaption, the coding rate can be fixed or (pre-) configured.

The resource elements are mapping firstly in the frequency domain and then time domain based on the principle that the same number of RBs are in each symbol. Further, the number of RBs in each symbol is same or smaller than the data/subchannel/BWP bandwidth. There can be a PRB_offset in the edge of data or subchannel for derive the starting PRB of the control channel.

For localized resource allocation as shown in Figure 3, the number of symbols X can be determined by satisfying the condition with the minimum X value:

Ceiling (total_SCI_RBs/X_symbols) <= M_RBs-PRB_Offset.

Or

Ceiling (total_SCI_RBs/X_symbols) <= M_RBs-2xPRB_Offset.

Wherein,

M_RBs is the total bandwidth of data or subchannel or BWP.

PRB_Offset is the gap or margin relative to the (both) edge of the data or subchannel.

The starting PRB index for control channel within the data or subchannel region can be PRB_Offset relative to the lowest index of the data or subchannel RBs.

Alternatively, the control channel can be located in the center of data or subchannel region, e.g., the RBs for control channel is determined as a range:

{LowestRBIndex, HighestRBIndex} = {referencePoint+ ceiling (M_RBs/2–L_RBs/2) , referencePoint+ ceiling (M_RBs/2 + L_RBs/2) } .

Wherein,

L_RBs is the number of RBs in one symbol for the control channel as derived previously.

referencePoint can be zero or (pre-) configured, e.g., the edge of (allocated/scheduled) data, subchannel or bandwidth part, which is used to derive the absolute RB index.

For distributed resource allocation as shown in Figure 4, it is similar as the localized resource allocation. The symbols for control channel can be determined same as the localized resource allocation. The only difference is the RE mapping starting from the both edge of the data/subchannel/BWP region with the RB index range as below:

- {LowestRBIndex, HighestRBIndex} for region 1 (i.e., lower part of the region in Figure 4) = {referencePoint+PRB_Offset, referencePoint+PRB_Offset + ceiling (L_RBs/2) } .

- {LowestRBIndex, HighestRBIndex} for region 2 (i.e., upper part of the region in Figure 4) = {referencePoint+M_RBs-PRB_Offset-ceiling (L_RBs/2) , referencePoint+M_RBs-PRB_Offset} .

DMRS location in frequency domain for the 1st SCI can be fixed. The reference signal for 1 ^st and/or 2nd SCI can reuse/share the data channel (PSSCH) DMRS wholly or partly with no need of the dedicated DMRS for 2 ^nd SCI to reduce the overhead. The dest (or source) UE/group ID can be used for sequence generation of the data channel (and 2nd SCI) DMRS, e.g., the initial value for sequence generation can be a function of the Dest UE/group ID. Alternatively, the reference signal for 1 ^st and/or 2nd SCI can have the own dedicated DMRS other than sharing data DMRS. It is possible to do the channel estimation for 1 ^st and/or 2 ^nd SCI based on the dedicated DMRS independently or jointly with data DMRS if the antenna port and/or transmission scheme is same for data and control channel. A field in the 1 ^st and/or 2 ^nd SCI can indicate whether the 1 ^st SCI DMRS and the 2 ^nd SCI/Data are QCL’ed (e.g., Type-A and/or Type-D QCl’ed relation as defined in 3GPP TS38.213) . If they are QCL’ed, both DMRSs can be used jointly for channel estimation to improve the performance.

Fig. 3 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. 8. 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 or pre-configuration for 2-stage SCI;

obtaining 1 ^st SCI;

receiving 2 ^nd SCI if presented based on information carried in 1 ^st SCI; and

receiving data based on 1 ^st SCI and 2 ^nd SCI if presented.
The method of claim 1, wherein a configuration or pre-configuration for 2-stage SCI is based on configuration from the network or group head device or groupcasting Tx device or stored information at device.
The method of claim 1, wherein 1 ^st SCI decoding is to obtain the data channel time-frequency location for data reception by the target receiving UE and sensing by the other UEs to perform resource selection.
The method of claim 1, wherein 2 ^nd SCI decoding is to obtain the remaining information about data reception for the target receiving UEs.
The method of claim 1, wherein 1 ^st SCI, 2 ^nd SCI and/or the single SCI sharing the same SCI size can be differentiated by the format indicator.
The method of claim 1, wherein the SRC ID and/or Dest ID can be either CRC scrambled in the 1 ^st SCI and/or 2 ^nd SCI.