CN112314006B

CN112314006B - Method, apparatus and computer readable medium for two-stage side link control information

Info

Publication number: CN112314006B
Application number: CN202080003330.XA
Authority: CN
Inventors: 陈滔; 唐治汛; 王荐一; 廖培凯; 雷敏
Original assignee: MediaTek Singapore Pte Ltd
Current assignee: MediaTek Singapore Pte Ltd
Priority date: 2019-04-03
Filing date: 2020-04-02
Publication date: 2024-03-08
Anticipated expiration: 2040-04-02
Also published as: WO2020199211A1; CN112314006A

Abstract

A method of two-level side link control information (SCI) includes the steps of: receiving a transport block, and transmitting a two-stage SCI (including a first-stage SCI and a second-stage SCI) and the transport block from a transmitting user equipment (Tx UE) to a receiving user equipment (Rx UE). The first stage SCI may be transmitted over a physical side link control channel (PSCCH). The second stage SCI and transport block may share resources of a physical side chain shared channel (PSSCH). The second stage SCI and the transport block may share demodulation reference signals (DMRS).

Description

Method, apparatus and computer readable medium for two-stage side link control information

Cross reference

The present invention claims priority from international patent application with application number PCT/CN2019/081565, name "2-Stage SCI for V2X Communication", application number 2019, 4 th, application number 201910296855.6, name "2-Stage SCI for V2X Communication". The contents of the above-mentioned patent application are incorporated herein by reference in their entirety.

Technical Field

The present invention relates to wireless communications, and in particular to side link (sidelink) communications.

Background

This background section is provided for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Cellular-based vehicle-to-evaluation V2X (e.g., long term evolution (Long Term Evolution, LTE) V2X or New Radio (NR) V2X) is a Radio access technology developed by the third generation partnership project (3rd Generation Partnership Project,3GPP) to support advanced vehicle applications. In V2X, a direct wireless link (referred to as a side link) may be established between two vehicles. The side links may operate under control of the cellular system (e.g., radio resource allocation) when the vehicle is within the coverage area of the cellular system. Alternatively, the side links may operate independently when no cellular system is present.

Disclosure of Invention

Aspects of the present invention provide a method of two-stage side link control information (sidelink control information, SCI). The method comprises the following steps: receiving the transport block and transmitting the two-stage SCI (comprising the first stage SCI and the second stage SCI) and the transport block from the transmitting user equipment (transmission user equipment, tx UE) to the receiving user equipment (reception user equipment, rx UE). The first stage SCI may be transmitted over a physical side link control channel (physical sidelink control channel, PSCCH). The second stage SCI and transport blocks may share resources of a physical sidelink shared channel (physical sidelink shared channel, PSSCH). The second stage SCI and the transport blocks may share demodulation reference signals (demodulation reference signal, DMRS).

In one example, the second stage SCI and the transport block are transmitted using the same transmission scheme with the same one or more antenna ports. In one example, polarity encoding is applied to the second stage SCI. In one example, the first stage SCI includes a field for determining the time-frequency location of the second stage SCI. In one embodiment, the method further includes performing a Resource Element (RE) mapping of the second level side link control information through resources of the PSSCH first in a frequency domain and then in a time domain.

In one embodiment, the first stage SCI indicates a modulation and coding scheme (modulation and coding scheme, MSC) for transmitting the transport block. In one embodiment, the resource size of the second level SCI may be determined based on the indicated MSC for transmitting the transport block. In one example, the first stage SCI and the second stage SCI are multiplexed in different symbols in the time domain or different physical resource blocks in the frequency domain. In one example, the first stage SCI includes information for an antenna port used to transmit the PSSCH. In one example, the first stage SCI includes a field for indicating whether a DMRS of the first stage SCI is quasi co-located (QCLed) with the second stage SCI and whether a transport block is transmitted through the PSSCH. Alternatively, the UE may assume QCL transmission between the first-level SCI and the second-level SCI (e.g., QCL transmission between the DMRS of the first-level SCI and the DMRS of the second-level SCI) so that joint channel estimation may be applied.

Aspects of the present invention provide an apparatus comprising a circuit. The circuitry is configured to receive a transport block and to transmit a two-stage SCI (including a first stage SCI and a second stage SCI) and the transport block from the Tx UE to the Rx UE. The first stage SCI may be transmitted over the PSCCH. The second stage SCI and transport block may share the resources of the PSSCH. The second stage SCI and transport block may share DMRS.

Aspects of the present invention provide a non-transitory computer readable medium storing program instructions that, when executed by a processor, cause the processor to perform a method of two-stage SCI.

The two-stage SCI method provided by the invention can improve the frequency spectrum efficiency without increasing the decoding complexity and is beneficial to subsequent evolution and expansion.

Drawings

The present invention sets forth several embodiments for illustrative purposes, and is described in detail below with reference to the drawings, wherein like numbers represent like components, and wherein:

fig. 1 illustrates a wireless communication system 100 according to an embodiment of the present invention;

fig. 2 shows an example of a resource pool 200 configured for side-link communication according to an embodiment of the present invention;

FIG. 3 illustrates an example of side link transmission 300 of a two-stage SCI in accordance with an embodiment of the present invention;

FIG. 4 illustrates another example of side link transmission 400 of a two-stage SCI in accordance with an embodiment of the present invention;

fig. 5 shows a scenario where the first stage SCI and the second stage SCI are time division multiplexed (time division multiplexed, TDM);

FIG. 6 shows a scenario where the first level SCI and the second level SCI are frequency division multiplexed (frequency division multiplexed, FDM);

FIG. 7 shows an example of localized resource allocation according to an embodiment of the present invention;

FIG. 8 shows an example of distributed resource allocation according to an embodiment of the present invention;

FIG. 9 illustrates a process 900 for side link transmission of a two-stage SCI in accordance with an embodiment of the present invention;

fig. 10 illustrates an exemplary apparatus 1000 according to an embodiment of the invention.

Detailed Description

Fig. 1 illustrates a wireless communication system 100 according to an embodiment of the present invention. The wireless communication system 100 includes a Base Station (BS) 101, a first UE 102, and a second UE 103.BS 101 may be an implementation of a gNB specified in the 3GPP NR standard or may be an implementation of an eNB specified in the 3GPP LTE standard. Accordingly, BS 101 may communicate with UE 102 or UE 103 via a radio interface (referred to as Uu interface 110) according to a corresponding wireless communication protocol. Alternatively, BS 101 may implement other types of standardized or non-standardized radio access technologies and communicate with UE 102 or UE 103 in accordance with the respective radio access technologies. UE 102 or UE 103 may be a vehicle, a computer, a mobile phone, a road side unit (roadside unit), etc.

UEs 102 and 103 may communicate with each other based on V2X technology specified in the 3GPP standards. A direct radio link, referred to as a Sidelink (SL), may be established between UE 102 and UE 103. The UE 102 may use the same spectrum for uplink transmissions over Uu link 111 and for side link transmissions over side link 120. Similarly, the UE 103 may use the same spectrum for uplink transmissions over Uu link 112 and for side link transmissions over side link 120. Further, BS 101 may control the allocation of radio resources on side link 120.

Unlike the example of fig. 1 (in-coverage scenario), in the above scenario, the UE 102 and the UE 103 performing side link communication are in the network range (in the coverage of the cell of the BS 101), and in other examples, the UE performs side link transmission outside the network coverage. For example, a side link may be established between two UEs that are both outside of network coverage (out-of-coverage scenario) or between UEs where one of the UEs is outside of network coverage (partial coverage scenario).

In some examples, a group of UEs in a local area (e.g., UE 102 and UE 103) may communicate with each other using side chains under control of a base station or not under control of a base station. Each UE in the group may send a message to neighboring UEs periodically or aperiodically. Further, the corresponding transmission may be unicast, multicast or broadcast. For example, HARQ and link adaptation (link adaptation) mechanisms may be employed to support unicast or multicast between the Tx UE and the target UE.

Fig. 2 shows an example of a resource pool 200 configured for side-link communication according to an embodiment of the present invention. For example, the resource pool 200 may be configured from the BS 101 to the UE 102, or may be preconfigured to the UE 102 (e.g., the resource pool configuration is stored in a universal integrated circuit card (universal integrated circuit card, UICC) of the UE 102). The resource pool 200 may be defined by a time/frequency (time slot, subchannel) resource grid 210. Radio resources for transmitting physical channels (e.g., PSCCH, PSSCH, etc.) from UEs on the side link 120 may be allocated based on the resource pool 200.

As shown, the system bandwidth 201 of the UE 102 includes subchannels #0- #6. Each sub-channel includes a plurality of physical resource blocks (physical resource block, PRBs) (or RBs, e.g., 5, 10, or 20 PRBs). The resource pool 200 includes a set of contiguous (or non-contiguous) subchannels #1- #3 in the frequency domain. If UE 102 is operating in bandwidth part (BWP) 202, the subchannels of resource pool 200 may be configured to operate in BWP 203. In the time domain, the resource pool 200 includes a plurality of time slots (e.g., slots #0- #4 and #6- # 7), which may be contiguous or non-contiguous in different examples.

The resource pool may be (pre) configured to the UE 102 from a transmission perspective (Tx pool) and a reception perspective (Rx pool), respectively. Thus, UE 102 may monitor the PSCCH and thus receive corresponding PSSCH transmissions from other UEs of the Rx pool (e.g., resource pool 200) when transmitting.

In one embodiment, two resource allocation modes (mode 1 and mode 2) are used to allocate radio resources for PSCCH and PSSCH transmission over the side link. In mode 1, the BS 101 performs a function of resource scheduling. For example, BS 101 provides dynamic grants of sidelink resources or grants of semi-static configuration of periodic sidelink resources (referred to as sidelink configuration grants) to UE 102 for sidelink communication over sidelink 120.

Dynamic side link grants may be provided in the downlink control information (downlink control information, DCI) and the resources are scheduled for initial transmission of a transport block and optionally retransmission of the same transport block. The retransmission may be a blind (blindly) retransmission or may be a retransmission in response to HARQ feedback. In one example, the resources for each transmission or retransmission may span one or more word channels, but are limited to one time slot in the sidelink resource pool 200.

The corresponding side link configuration grants, and the scheduling resources may be a set of periodically repeated side link resources. The use of side-chain configuration grants may be initiated or terminated with activation or deactivation signaling via DCI.

Mode 2 may be used for resource scheduling (resource allocation) when the UE 102 is in an out-of-coverage state, or when the UE 102 is in coverage but indicated by the BS 101. In mode 2, the UE may automatically select resources for side link transmission based on the sensing procedure. For example, the UE 102 may sense in a (pre) configured resource pool which resources are not used by other UEs with higher priority traffic and select an appropriate number of resources for the side-link initial transmission and optional retransmission. In such resources selected, the UE may make a certain number of transmissions and retransmissions.

For example, the UE 102 may reserve resources for multiple blind (re) transmissions of a transport block or (re) transmissions based on HARQ feedback. UE 102 may also reserve resources for initial transmission of subsequent transport blocks. Reserved resources may be indicated in the SCI scheduling the transmission of the transport block. Alternatively, the initial transmission of the transport block may be performed after sensing and resource selection, but without reservation.

The SCI (e.g., first level SCI) that the UE transmits on the PSCCH indicates the selected time-frequency resources that each UE uses to transmit the PSCCH. (indicated time-frequency resources may be allocated with either mode 1 or mode 2.) these SCI transmissions may be used by the sensing UE 102 to maintain a record that the most recent resources have been reserved by other UEs. When triggering resource selection (e.g., by traffic arrival or resource reselection triggering), the UE 102 considers a sensing window that starts from a time of past (pre) configuration and ends shortly before the trigger time. For example, the sensing UE 102 also measures PSSCH-reference signal received power (Reference Signal Receiving Power, RSRP) on selected or reserved resources in the slots of the sensing window. The measurements may indicate the interference level that would be experienced if the sensing UE 102 were to transmit in the selected or reserved resources.

The sensing UE 102 may then select resources for transmission or retransmission from within the resource selection window. For example, the resource selection window starts after triggering the transmission and cannot be longer than the remaining waiting delay budget of the transport block to be transmitted. Based on SCI from other UEs and the measurements as described above, the sensing UE 102 excludes selected or reserved resources of other UEs having a PSSCH-RSRP greater than a threshold in the selection window from candidates. The threshold may be set according to the priority of the traffic of the sensing UE and other transmitting UEs (e.g., priorities associated with the respective transport blocks). Thus, higher priority transmissions from the sensing UE 102 may occupy resources reserved by transmitting UEs with sufficiently low PSSCH-RSRP and low priority traffic.

From the set of resources not excluded from the selection window, the sensing UE may identify a certain percentage (e.g., 20%) of the available resources within the window as candidate resources. UE 102 may select resources from among the candidate resources for a plurality of initial transmissions or retransmissions (e.g., in a random manner) of the transport block to be transmitted.

Fig. 3 shows an example of a side link transmission 300 of a two-stage SCI according to an embodiment of the present invention. In the side-link transmission 300, the UE 102 generates and transmits a PSCCH 310 and a PSCCH 320 associated with the PSCCH 310. PSCCH 310 may carry a first stage SCI 311 and pssch320 may carry a second stage SCI 321 and data 322 (e.g., transport block data). For example, a first level or second level SCI (e.g., channel coding, modulation, precoding, etc.) may be generated and processed on the physical layer before being mapped to Resource Elements (REs) in a corresponding physical channel (e.g., PSCCH 310 or PSSCH). Such as PSCCH 310 or pscsch 320). The transport blocks may be received from a higher layer (e.g., medium access control (medium access control, MAC) layer) and processed (e.g., channel coded, modulated, precoded, etc.) at the physical layer before being mapped to REs in the corresponding PSSCH 320.

In one example, UE 102 may be configured to perform each transmission or retransmission of a transport block or other type of data in one slot of the time domain. Thus, as shown in fig. 3, the resources used to transmit PSCCH 310 and pscsch 320 may be selected in a pool of Tx resources within one or more sub-channels of the time domain and the frequency domain. In one example, one slot may include 14 symbols (e.g., orthogonal frequency division multiplexing (orthogonal frequency division multiplexing, OFDM) symbols), but may have different durations depending on the respective subcarrier spacing. For example, a 1ms subframe may include 1, 2, or 4 slots, each slot including 14 symbols, corresponding to different subcarrier spacings of 15kHz, 30kHz, or 60 kHz.

In other examples, PSCCH 310 and PSSCH 320 may be transmitted in different time slots. Accordingly, resources may be selected from different time slots of the Tx resource pool to transmit PSCCH 310 and PSSCH 320.

In fig. 3, PSCCH 310 and pscsch 320 are shown as being Time Division Multiplexed (TDM). However, in other examples, PSCCH 310 and PSSCH 320 may be Frequency Division Multiplexed (FDM). For example, within the bandwidth of the allocated sub-channel in fig. 3, resources on PSCCH 310 may also be allocated for transmission of PSCCH 320.

Fig. 4 shows another example of a side link transmission 400 of a two-stage SCI according to an embodiment of the present invention. In side link transmission 400, UE 102 generates and transmits PSCCH 410 and PSSCH420 associated with PSCCH 410. PSCCH 410 may carry a first stage SCI 411 and pssch 320 may carry a second stage SCI 421 and data 422 (e.g., transport block data). Similar to the example of fig. 3, the time-frequency resources used to transmit PSCCH 410 and PSCCH 420 may be selected within one slot in the time domain of a Tx resource pool or one or more subchannels in the frequency domain, unlike fig. 3, PSCCH 420 and PSCCH 410 are TDM and FDM.

In addition, as shown in fig. 4, the PSSCH420 may be multiplexed with DMRS mapped to a plurality of symbols 423A, 423B, and 423C (referred to as DMRS symbols). In one example, each PRB in a DMRS symbol includes REs to which a DMRS is mapped. In some examples, REs carried in one DMRS symbol may form a comb-like structure (comb-like structure). REs that do not carry DMRS in one DMRS symbol may be used to carry second-stage SCI 421 or data 422.

In the examples of fig. 3 and 4, two stages of SCI are used for side link transmission. The corresponding side link transmission 300 or 400 may be of unicast, multicast or broadcast type. During transmission 300/400, first stage SCI 311/411 may be used for sensing purposes and for all UEs in the vicinity of Tx UE 102 (all UEs refer to UEs that first stage SCI 311/411 can reach). Thus, the first stage SCI 311/411 may carry information related to channel sensing and be transmitted in a broadcast manner (e.g., low coding rate) so that the first stage SCI 311/411 may be decoded by all neighboring UEs.

In contrast, the second level SCI 321/421 is directed to UEs involved in unicast or multicast communications (the target UE is a subset of all UEs). Thus, the second stage SCI 321/421 may carry the information needed to decode the data 322/422 (e.g., new data indicator and redundancy version (redundancy version, RV)) and may transmit over link adaptation based on channel conditions between the Tx UE 102 and the target UE.

For example, a high coding rate may be used to transmit the second stage SCI 321/421 to improve spectral efficiency. The high coding rate may be determined based on a signal-to-noise ratio (signal to noise ratio, SNR) level of a channel between the Tx UE 102 and the target UE. In one example, a polar code is used for channel coding of the second stage SCI 321/421.

In one embodiment, the first stage SCI 311/411 may have a fixed size (fixed number of bits) for unicast, multicast or broadcast. In addition, the first stage SCI 311/411 may have a fixed aggregation level. In other words, the first stage SCI 311 may have a fixed number of REs for transmission. Furthermore, the time/frequency location of the resources allocated to the first stage SCI 311 may be preconfigured to be fixed. With a fixed size, number of REs, and time/frequency location, the sensing UE or receiving UE may decode the first stage SCI 311 without blind detection decoding. Thus, the decoding complexity of the PSCCH 310/410 may be reduced.

In one embodiment, the second stage SCI 321/421 may similarly be of a fixed size. During unicast or multicast communications, link adaptation may be employed to transport the second level SCI 321/421, resulting in different aggregation levels (or different numbers of REs). To avoid or reduce the complexity of blind detection of the second level SCI 321/421 at the receiving UE, the first level SCI 311/411 may (explicitly or implicitly) indicate the resource size (or number of REs) of the second level SCI 321/421 and/or the time/frequency location of the second SCI 321/421. Thus, two-stage SCI transmission may utilize link adaptation to transmit the second stage SCI 321/421, thereby improving spectral efficiency without increasing decoding complexity. In contrast, single-level transmission with link-adapted SCI will result in blind decoding, thereby increasing decoding complexity.

In some embodiments, multi-antenna transmission is employed. For example, the PSSCH 320/420 in the example of FIG. 3 or FIG. 4 can be transmitted using one of various transmission schemes corresponding to various transmission modes specified in the 3GPP LTE or NR standards. Examples of transmission schemes include precoder-based multi-antenna transmission, multi-user multiple-input and multiple-output (MIMO), transmit diversity, and the like. One or more antenna ports may be used for transmission of the PSSCH 320/420 (e.g., in multiple layers) corresponding to one transmission scheme. Thus, the second stage SCI 321/421 and corresponding data 322/422 can be transmitted using the same transmission scheme and the same antenna port. For transmissions on each antenna port, the second-level SCI and corresponding data for the same layer may share the same DMRS, and no dedicated DMRS need be configured for the second-level SCI 321/421. In this way, the overhead (resource occupation) of the reference signal can be reduced.

For example, when multi-antenna transmission is employed, the first stage SCI 311/411 may carry antenna port information and/or DMRS pattern information of the corresponding PSSCH 320/420. For example, the number of antenna ports (the number of antenna ports that have been used) may be indicated in the first stage SCI 311/411. And/or one or more indices of the antenna ports used may be indicated in the first stage SCI 311/411. In addition, DMRS patterns may be indicated in first stage SCI 311/411 (e.g., defining the number and location of DMRS symbols). Different DMRS patterns may be used depending on the relative speed between the Tx UE 102 and the receiving UE. Based on the antenna port information and DMRS pattern information carried in the first stage SCI 311/411, the receiving UE may determine the corresponding DMRS and perform channel estimation and thus decode the second stage SCI 321/421 and data 322/422 transmitted in the same antenna port as the corresponding DMRS.

In one embodiment, PSCCH 310/410 may also have DMRS multiplexed over one or more symbols (PSSCH DMRS described above with respect to PSCCH 320/420 is referred to as PSCCH DMRS). The first stage SCI 311/411 may be used to indicate whether PSCCH DMRS is in a QCL (e.g., type A and/or type D QCL relationship as defined in 3GPP TS 38.213) field with PSSCH DMRS (or second SCI 321/421 and/or data 322/422). When the indications PSCCH DMRS and PSSCH DMRS are in QCL, the receiving UE may accordingly combine PSCCH DMRS with PSSCH DMRS for channel estimation to improve performance. The result of the channel estimation can be used for coherent demodulation of the PSSCH 320/420. Alternatively, the UE may assume QCL transmission between the first level SCI and the second level SCI, e.g., QCL transmission between the DMRS of the first level SCI and the DMRS of the second level SCI.

In one embodiment, the first stage SCIs 311/411 may include one or more fields for indicating the time-frequency location of the corresponding second stage SCIs 321/421. For example, first stage SCI 311/411 may include a field (e.g., including a code point) indicating the number of subchannel(s) allocated for transmission of PSSCH 320/420. In addition, PSCCH 310/410 may be configured to be located at the bottom of an allocated subchannel. Thus, the receiving UE may first detect the location of PSCCH 310/410 in the frequency domain (according to configuration) and then use the information of the allocated subchannels carried in the first stage SCI to determine the frequency location of PSCCH 320/420.

In one example, the time domain location of the corresponding second stage SCI 321/421 may be determined based on DMRS pattern information carried in the first stage SCI 311/411. For example, as shown in fig. 4, the RE mapping of the second stage SCI 421 may be configured to start in the time domain from the first DMRS symbol 423A of the PSSCH 420 and to proceed to the next symbol (e.g., symbol 424) adjacent to the first DMRS symbol 423A. Thus, based on such a configuration, the receiving UE can determine the time position of the corresponding second-stage SCI 321/421 from the DMRS pattern information carried in the first-stage SCI 311/411. In some other examples, RE mapping of the second stage SCI 321/421 can be configured to begin in the time domain at the first symbol of the resource of PSSCH 320/420.

Although the first DMRS symbol 423A is shown as the first symbol of the PSSCH 420 in the example of fig. 4, in other examples, the first DMRS symbol corresponding to the DMRS pattern may be located on other symbols than the first symbol of the PSSCH. For example, DMRS symbol 423A is not transmitted in examples with different DMRS patterns. DMRS symbol 423B becomes the first DMRS symbol. Thus, RE mapping of second stage SCI 421 may begin with DMRS symbol 423B.

In one embodiment, RE mapping of second stage SCI 321/421 is performed in a frequency domain first and time domain second manner. For example, from a starting symbol (e.g., the first DMRS symbol 423A in fig. 4), the second stage SCIs 321/421 map to the available REs of the starting symbol (except for REs occupied by the DMRS) and they map to the next symbol. In one example, mapping may be performed by first mapping to all PRBs in all sub-channels of PSSCH 320/420 in a starting symbol, and then proceeding to the next symbol.

In one example, the UE 102 may perform link adaptation to transmit the data 322/422 based on the radio link quality of the target channel. The radio link quality may be indicated by a channel quality indicator (channel quality indicator, CQI) provided from the Rx UE. Depending on the radio link quality, and with a target error probability (e.g., block error rate (BLER) less than 10%), UE 102 may determine an MCS (or MCS index) for transmitting data 322/422 to the Rx UE over the target channel. The MCS index may correspond to a modulation level and a coding rate used to transmit the data 322/422.

The UE 102 may also perform a second link adaptation to the second level SCI 321/421. Since the second stage SCI 321/421 and the data 322/422 will be transmitted on the same target channel, link adaptation of the second stage SCI 321/421 can target the SNR level of the target channel as the link adaptation of the data 322/422. However, the transmissions of the second stage SCI 321/421 may have different target error probabilities (e.g., BLER less than 1%). Thus, different coding rates can be determined for the transmissions of the second stage SCI 321/421.

In addition, as described above, the size (number of bits) of the second stage SCI 321/421 can be fixed. Thus, when determining the coding rate of the second stage SCI 321/421, the number of bits to be transmitted (the number of bits carried in the RE) can be determined. In one embodiment, the modulation level of the second stage SCI 321/421 may be preconfigured as quadrature phase shift keying (quadrature phase shift keying, QPSK), and thus the RE may carry a modulation symbol corresponding to 2 bits. Thus, the number of REs used to transmit the second stage SCI 321/421 can be determined by dividing the number of bits to be transmitted by the number of bits carried in one RE (2 bits for QPSK). As a result of the link adaptation, the resource size (number of REs) for transmitting the second level SCI 321/421 may be determined at the UE 102.

As described above, the transmission of corresponding data in the second stage SCI and the same PSSCH targets the same SNR level. Thus, the link adaptations of the second stage SCI and the corresponding data are associated with each other. For example, the SNR level may be determined corresponding to the MCS of the transmitted data; the resource size (or coding rate) for transmitting the second level SCI may be determined corresponding to the SNR level. Thus, in one embodiment, the mapping relationship between the resource size for transmitting the second level SCI and the MCS for transmitting the corresponding data is defined for different link adaptation scenarios (e.g., different radio link quality). When the PSSCH is transmitted at the UE 102, the MCS for transmitting the data can be first determined, and then the resource size for transmitting the corresponding second level SCI can be correspondingly determined based on the predefined mapping relationship. In one example, the mapping relationship may be specified in the form of a mapping table.

Similarly, the mapping relationship defined above may be used at the receiving UE. For example, first stage SCI 311/411 may include a field indicating the MCS used to transmit data 322/422. At the receiving UE, based on the mapping relationship defined above, the receiving UE may determine the resource size of the second level SCI 321/421 based on the MCS indicated in the first level SCI 311/411. In addition, the first stage SCI 311/411 may further include a field indicating a time-frequency start position (e.g., bandwidth of the PSSCH 320/420 and DMRS pattern) of the second stage SCI. Based on the RE mapping rules (first frequency domain, then time domain), resource size, starting position, the Rx UE can efficiently determine the REs carrying the second level SCI 321/421 in the radio resource grid. Thus, blind detection of the second stage SCI 321/421 can be avoided.

Other embodiments related to two-stage SCI are described below.

In one embodiment, for V2X side-chain communications, the PSSCH may be scheduled by SCI carried in the PSCCH. In one embodiment, the second level SCI may be used for sensing and broadcast communication purposes by applying the first level SCI (or referred to as the first SCI), while the second level SCI (or referred to as the second SCI) carries the remaining information of the data schedule for unicast/multicast data transmission.

In one embodiment, the second level SCI time/frequency location may be derived from an information field carried in the first level SCI. In one embodiment, both the first stage SCI and the second stage SCI may use either centralized or distributed frequency resources for transmission. In one embodiment, the first stage SCI and the second stage SCI may be time domain multiplexed in different symbols and/or frequency domain multiplexed in different PRBs (interleaved or non-interleaved). In some embodiments, the second stage SCI may share/use time/frequency resources reserved for a data channel (e.g., PSSCH).

The second stage SCI may have a link adaptation associated with a data channel link adaptation. The second stage SCI may have the same transmission scheme as a data channel with the same antenna port or a different transmission scheme with different antenna ports but with the same power per resource element.

In one embodiment, power boosting (power boosting) may be applied between the sidelink control channel and the data channel. The power offset may be indicated during side chain radio resource control (radio resource control, RRC) connection setup for unicast/multicast communications, as well as in the first stage SCI.

In one example, DMRS locations in the frequency domain for the first stage SCI may be fixed. The reference signals of the first and/or second stage SCIs may reuse/share data channel (PSSCH) DMRS in whole or in part without requiring dedicated DMRS for the second stage SCIs to reduce overhead. The target (dest) (or source) UE/group ID may be used for sequence generation of the data channel DMRS (also shared by the second level SCI). Alternatively, the reference signals for the first and/or second stage SCIs may have their own dedicated DMRS instead of the data channel DMRS. If the antenna ports and/or transmission schemes of the data and control channels are the same, channel estimation may be performed on the first and/or second stage SCI based on the dedicated DMRS, either independently or together with the data DMRS.

The channel coding of the second stage SCI may use polar codes. A shorter cyclic redundancy check (cyclic redundancy check, CRC) (e.g., 16-bit CRC) may be applied to the second stage SCI (and/or the first stage SCI) to reduce CRC overhead.

In some examples, it may be indicated in the first stage SCI whether the DMRS of the first stage SCI and the DMRS of the second stage SCI/data are QCL or whether the same transmission scheme is used based on the same antenna port. Then, channel estimation for the second level SCI/data may or may not use the first level SCI DMRS, depending on the indication at the receiving UE. Alternatively, the UE may assume QCL transmission between the first level SCI and the second level SCI (e.g., QCL transmission between DMRS of the first level SCI and DMRS of the second level SCI) in order to apply joint channel estimation.

As an example, table 1 shows a comparison between fields of a two-stage SCI (including a first-stage SCI and a second-stage SCI) and a single SCI, according to some embodiments.

TABLE 1

In table 1, the "format indicator" may be 1 bit or more of information to indicate whether it is a first level SCI for scheduling broadcast messages and/or at least a first level SCI for sensing purposes. If used to schedule broadcast transmissions, the second level SCI need not be followed. If it is used for sensing purposes (e.g., for unicast/multicast), the second level SCI will be followed to carry the remaining information (e.g., scheduling information for unicast/multicast message reception). Furthermore, the first level SCI may also be used to carry sensing information of unlicensed transmissions (RRC-based unlicensed transmissions similar to type 1 unlicensed transmissions in Uu interface or SCI-based unlicensed transmission semi-persistent scheduling (semi-persistent scheduling, SPS) transmissions similar to Uu interface or type 2 unlicensed transmissions in Uu interference). In this case, a second level SCI may not be needed, as detailed scheduling information is already carried in the configuration message by the setup or (pre) configuration. For example, such a first stage SCI for the purpose of sensing grant-less transmissions may be sent periodically based on a (pre) configuration, or may be sent together with each data transmission based on the sensing result. It may be transmitted with the data or may be transmitted earlier than the data for sensing purposes.

In addition, the format indicator may further indicate whether there is only a first level SCI transmission for sensing purposes, without any second level SCI for scheduling information and scheduling information for data. For example, for unlicensed transmission, the target UE already knows the data scheduling information based on (pre) configuration or UE-UE signaling. The first stage SCI is then used only for sensing purposes to be decoded by other UEs than the intended UE. In this case, the second level SCI is not required, nor is at least the MCS information in the first level SCI.

The "source/target UE/group ID" may be an 8/16/24 bit field. For broadcast messages or communications, source/target UE/group IDs may not be required. Meanwhile, synchronous HARQ is applied to broadcast transmission by indicating retransmission time through a "time interval between initial transmission and retransmission" field. For unicast/multicast, due to asynchronous HARQ, a "time interval between initial transmission and retransmission" may not be needed.

The target UE/group ID may be included in the first level SCI to indicate the intended UE for the second level SCI and data reception so that unintended UEs do not need to receive the second level SCI and related data. Meanwhile, the target UE/group ID may be used for DMRS sequence generation, for example, an initial value for sequence generation may be a function of the target UE/group ID. In the case of unlicensed transmission, the source/target UE/group ID may not be included in the first level SCI (in which case the second level SCI may not be needed) as it is decoded by other UEs for sensing purposes only. The scheduling information for the unlicensed transmission (at least the first transmission) is already (pre) configured and SCI transmission is not required. Alternatively, the target ID may be included in the first stage SCI for unlicensed transmission sensing, which provides the potential to exploit the spatial multiplexing gain through the IC by multiplexing the same time/frequency resources as the target UE to achieve active interference cancellation.

The "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 the time resources to be used for the upcoming transmission.

The "frequency resource location" may be used to indicate the frequency domain resource allocation for the transmission of data (including the second level SCI), or the frequency offset of the lowest index of the physical resource block (or subchannel) for the last data transmission.

The "time interval between initial transmission and retransmission" may be used to derive the timing of the retransmission or the corresponding initial transmission. In the case of asynchronous HARQ for unicast/multicast, a "time interval between initial transmission and retransmission" may not be required.

The "retransmission index" is used to indicate the first transmission or retransmission.

The "modulation and coding scheme" may be used to indicate an MCS level for the broadcast communication. In case of unicast/multicast with secondary SCI transmission, exact MCS information can be carried in the secondary SCI. Alternatively or additionally, one or several modulation levels (e.g., QPSK, 16QAM, 64QAM, 256 QAM) may be indicated in the first stage SCI to derive the target SIN or retransmission.

The "transport format" may be used to indicate whether Transport Block (TB) scaling is applied or which MCS table (with up to 64QAM tables or with up to 256QAM tables) associated with the interpretation of the MCS field is used.

The "new data indicator" indicates whether a new transmission or retransmission is performed.

The "redundancy version" indicates the RV version of the transmission.

The "number of HARQ processes" indicates the number of HARQ processes to be used for HARQ combining.

The "a-CSI request" requests the UE to measure and report aperiodic channel state indicators (aperiodical channel state indicator, a-CSI). The CSI to be measured may be DMRS of the first level SCI, the second level SCI and/or data DMRS occurring at the same time slot of the corresponding SCI transmission.

The "DMRS TDM pattern" indicates the number and location of data DMRS in the time domain. The start symbol of the data DMRS may be indicated by another field or configured by the network, SL connection setup message or UE (pre). For example, the start symbol of the data DMRS is always located in the first symbol of the slot or in the first symbol of the slot for SL transmission, or in the first symbol for SL transmission or immediately after the first stage SCI transmission.

"second stage SCI T/F location" indicates the time/frequency location of the second stage SCI.

The "reserved bits" may be available for future use or later determination (TBD).

The "CRC" field is used to carry CRC bits. Further scrambling may be by UE/group ID (target and/or source UE/group ID). The CRC bits may be 8 bits, 16 bits, or 24 bits. In the case of a 24 bit CRC and 24 bit ID, all 24 bits may be scrambled in the CRC of the second stage SCI. Alternatively, at the end of the 16-bit CRC of the 24-bit CRC, only the 16 bits of the ID (most or least) may be scrambled. The remaining 8 bits of the ID may be explicitly carried in the payload of the second stage SCI. A similar approach may be applied to the case with a 16-bit CRC and a 16-bit UE ID.

In addition, the following information may be carried: (1) port number information and ports. (2) fields of different sizes of the second stage SCI. For example, 2 bits may be used to indicate one of four different sizes predefined in the table. The time/frequency location of the second stage SCI indicated by the "second stage SCI T/F location" may be interpreted differently depending on the size of the SCI. (3) A field representing the first level SCI, the second level SCI and/or the start symbol of the data transmission. (4) A field indicating the lowest PRB index for the first level SCI, the second level SCI, and/or the data transmission.

In one embodiment, the second level SCI time/frequency location may be derived from an information field carried in the first level SCI. Both the first stage SCI and the second stage SCI may use either centralized or distributed frequency resources for transmission. The first stage SCI and the second stage SCI may be time domain multiplexed in different symbols and/or frequency domain multiplexed in different PRBs (interleaved or non-interleaved). The second stage SCI may share/use time/frequency resources reserved for the corresponding data channel.

Fig. 5 shows a scenario where the first stage SCI and the second stage SCI are TDM. Unlike that shown in fig. 5, in other examples, the first stage SCI and the second stage SCI may be mapped to a plurality of symbols, respectively.

Fig. 6 shows another scenario where the first level SCI and the second level SCI are FDM. Similarly, in different examples, the first level SCI and the second level SCI may be mapped to multiple symbols, respectively.

In one embodiment, 2-4 bits may be used in the first stage SCI to explicitly indicate the second stage SCI location. Each code point (or entry) may indicate one of the time/frequency locations of the predefined second level SCI in the mapping table.

In one embodiment, the second level SCI location may be derived based on one or more fields in the first level SCI indicating the modulation level, modulation subset, or MSB/LSB bits of the MCS index in the MCS table used for data transmission. For example, the modulation to be used for the data may determine the target SINR level. Assuming that the payload size of the second-level SCI is fixed, the resource size (e.g., total number of PRBs) of the second-level SCI is a function of the modulation level used for data transmission due to link adaptation and data transmission. For example, the resource size may be derived from the data modulation level linked to the target SINR/SNR level. Such target SINR/SNR levels may be used to determine a coding rate. The resource size may then be determined based on the coding rate and the payload size. Table 2 shows an example of a mapping table in which different resource sizes of the second stage SCI are mapped with different modulation levels indicated in the first stage SCI.

TABLE 2

In addition, the respective time/frequency position or resource size (e.g., number of symbols in time domain and number of PRBs in frequency domain) of each resource or resource size may be derived based on a predefined rule or (pre) configuration (e.g., a (pre) configuration of starting symbols and/or lowest index of PRBs of the second stage SCI, or a (pre) configuration of relative/fixed offset in time/frequency domain with respect to data resource allocation).

In the case of multiple combinations of time and frequency resources, the determination may be made based on the data resource configuration. For example, the bandwidth of the second stage SCI is selected from a set of values that are close to the data or subchannel bandwidth. For example, for the second level SCI bandwidth, using a set of values {12, 24, 48, 96} RBs, and representing the data transmission bandwidth as 50 RBs, the second level SCI bandwidth is selected to be 48 RBs, i.e., close to but less than the data bandwidth. Furthermore, prb_offset may be used as a constraint, e.g., close to but smaller than Data bw_prb-prb_offset. Such prb_offset may be used to leave prb_offset/2 PRBs at each edge of the bandwidth and protect the second stage SCI from in-band transmission interference. Such prb_offset may be (pre) configured by the base station or UE. Based further on the total number of selected bandwidths and resource sizes, the number of symbols in the time domain may be determined accordingly as:

Symbol number = round down (floor) (total number of RBs/number of RBs per symbol) or round up (lifting) (total number of RBs/number of RBs per symbol)

Tables 3 and 4 together show examples of determining the MCS for data transmission based on field combinations in the first level SCI and the corresponding second level SCI.

TABLE 3 Table 3

Table 4 shows an example of a modulation scheme, a transport block size (transport block size, TBS) index, and a redundancy version table of the SL data channel.

TABLE 4 Table 4

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In one embodiment, the final data MCS may be derived by constructing a new MCS table using a combination of fields in the first level SCI and the second level SCI. Such a solution may reduce signaling overhead by indicating a portion of the MCS information for data transmission and resources (size) for the second level SCI at the same time. Table 5 shows an example of modulation, TBS index and redundancy version table for SL data channels based on a combination of fields in the first level SCI and the second level SCI.

TABLE 5

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Similarly, if the MCS index range is used instead of the modulation level, the resources (size) for the second level SCI can be derived. Table 6 shows an example table indicating the mapping between the MCS index range of the second level SCI and the resource (size).

TABLE 6

In some embodiments, multi-antenna transmission is employed. Thus, the antenna port information (number of antenna ports and/or index of antenna ports) may be carried in the first stage SCI. In case of different layers (or different numbers of antenna ports) for (second level SCI) transmission, the corresponding resources (sizes) may be different. Thus, the number of antenna ports may be further used to determine second level SCI resources. For example, the second level SCI resource (size) is a function of the number of antenna ports. The more layers of the second layer SCI, the smaller the size of each layer due to the multi-layer transmission.

In one embodiment, the second stage SCI may have a link adaptation associated with a data channel link adaptation. The second stage SCI may have the same transmission scheme as a data channel with the same antenna port or a different transmission scheme with different antenna ports but with the same power per resource element. If the first level SCI can have multiple resources (sizes) or aggregate levels as link adaptation for the NR/LTE control channel, the second level SCI resources (sizes) can also be implicitly indicated or derived based on the detection of the first level SCI. For example, the second level SCI resource (size) is a function of the detected first level SCI resource size, or a predefined table based on a mapping relationship between the second level SCI resource (size) and the detected first level.

In one embodiment, localized and distributed resource allocation may be supported for first/second level SCI or single SCI resource allocation. The total number of PRBs (or RBs) of the side link control channel may be calculated by:

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

where targetCodingRate may be determined by a target SNR level that may be derived from a field (e.g., a data modulation level or MCS range) in the first stage SCI with a link adapted control channel. The coding rate may be fixed or (pre) configured for control channels without link adaptation.

In one embodiment, the resource elements are mapped first in the frequency domain and then in the time domain based on the principle of the same number of PRBs in each symbol. In addition, the number of RBs in each symbol is equal to or less than the data/subchannel/BWP bandwidth. Prb_offset may be present at the edges of the data or sub-channel to derive the starting PRB of the control channel.

Fig. 7 shows an example of localized resource allocation according to an embodiment of the present invention. As shown, the number of symbols X may be determined by satisfying the condition with a minimum X value:

ceiling (total_SCI_RBs/X_symbols) < = N_RBs-PRB_Offset, or

Ceiling(total_SCI_RBs/X_symbols)<＝N_RBs-2xPRB_Offset

Where n_rbs is the total bandwidth of the data or sub-channel or BWP, and prb_offset is the spacing or margin relative to the (two) edges of the data or sub-channel. The starting PRB index of the control channel within the data or subchannel region may be prb_offset with respect to the lowest index of the data or subchannel RB.

Alternatively, the control channel may be located at the center of the data or sub-channel region, e.g., the RB for the control channel is determined as a range:

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

where l_rbs is the number of RBs in one symbol of the previously derived control channel, and the reference point may be zero or (pre) configured, e.g. the edge of the (allocated/scheduled) data, sub-channel or bandwidth part, for deriving an absolute RB index.

Fig. 8 shows an example of distributed resource allocation according to an embodiment of the present invention. The symbols of the control channel may be determined in a manner similar to the local resource allocation in fig. 7. Unlike the example of fig. 7, RE mapping may start from both edges of the data/subchannel/BWP region, and the RB index range is determined as:

region 1 (i.e., the lower part of the region in fig. 4) { LowestRBIndex, highestRBIndex } = { reference point+prb_offset, reference point+prb_offset+training (l_rbs/2) }, and

region 1 (i.e., the lower portion of the region in fig. 4) { LowestRBIndex, highestRBIndex } = { reference point+m_rbs-prb_offset-blocking (l_rbs/2), reference point+m_rbs-prb_offset }.

In one embodiment, power boosting may be applied between the side link control channel and the data channel. The power offset may be indicated during side link RRC connection setup for unicast/multicast communications or in the first level SCI.

In one embodiment, the DMRS locations in the frequency domain for the first stage SCI may be fixed. The reference signals of the first and/or second stage SCIs may reuse/share data channel (PSSCH) DMRS in whole or in part without requiring dedicated DMRS for the second stage SCIs to reduce overhead. The target (or source) UE/group ID may be used for sequence generation of the data channel DMRS (also shared by the second level SCI). Alternatively, the reference signals for the first and/or second stage SCIs may have their own dedicated DMRS instead of the data channel DMRS. If the antenna ports and/or transmission schemes of the data and control channels are the same, channel estimation may be performed on the first and/or second stage SCI based on the dedicated DMRS, either independently or together with the data DMRS.

In one embodiment, a field in the first and/or second stage SCI may indicate that SCI 311/411 may be used to indicate that the first stage SCI DMRS and the second stage SCI/data are in QCL (e.g., type a and/or type D QCL relationships as defined in 3gpp ts 38.213). If in QCL, two DMRSs can be used together for channel estimation to improve performance. Alternatively, the UE may assume QCL transmission between the first level SCI and the second level SCI (e.g., QCL transmission between DMRS of the first level SCI and DMRS of the second level SCI) in order to apply joint channel estimation.

In one embodiment, the channel coding of the second stage SCI may use a polar code. A shorter CRC (e.g., 16 bit CRC) may be applied to the second stage SCI (and/or the first stage SCI) to reduce CRC overhead.

Fig. 9 illustrates an example process 900 for side link transmission of a two-stage SCI in accordance with an embodiment of the present invention. The process 900 may start from step S901 and proceed to step S910.

At step S910, a transport block is received on a physical layer of a Tx UE. For example, transport blocks are generated at a transport layer in a protocol stack and carried in a transport channel, referred to as a side link shared channel (sidelink shared channel, SL-SCH).

At step S920, the transport block may be processed at the physical layer and transmitted from the Tx UE to the Rx UE. A two-stage SCI comprising a first stage SCI and a second stage SCI may be used for said transmission. The first stage SCI may be transmitted over the PSCCH. The second stage SCI and transport block may share radio resources allocated to the PSSCH. The second stage SCI and transport block may share DMRS. No dedicated DMRS is sent for the second level SCI. The process 900 proceeds to step S999 and ends at step S999.

Fig. 10 illustrates an exemplary apparatus 1000 according to an embodiment of the invention. The apparatus 1000 may be configured to perform various functions described in accordance with one or more embodiments or examples herein. Thus, the apparatus 1000 may provide a means for implementing the techniques, processes, functions, components, systems described herein. For example, the apparatus 1000 may be used to implement the functionality in the various embodiments and examples described herein. The apparatus 1000 includes a general purpose processor or specially designed circuits for carrying out the functions, components or processes described in the various embodiments. The apparatus 1000 may include a processing circuit 1010, a memory 1020, and a Radio Frequency (RF) module 1030.

In various examples, processing circuitry 1010 may comprise circuitry configured to perform the functions and processes described herein, which may be implemented in connection with software or without. In various examples, the processing circuitry may be a digital signal processor (Digital Signal Processor, DSP), an application specific integrated circuit (Application Specific Integrated Circuit, ASIC), a programmable logic device (Programmable Logic Device, PLD), a field programmable logic gate array (Field Programmable Gate Array, FPGA), a digital enhancement circuit (digitally enhanced circuit), or comparable device or combination thereof.

In some other examples, the processing circuit 1010 may be a central processing unit (Central Processing Unit, CPU) configured to execute program instructions to perform the various functions and processes described herein. Accordingly, memory 1020 may be configured to store program instructions. When executing program instructions, the processing circuitry 1010 may perform functions and processes. Memory 1020 may also store other programs or data, such as an operating system, application programs, and the like. The Memory 1020 may include Read Only Memory (ROM), random access Memory (Random Access Memory, RAM), flash Memory, solid state Memory, hard disk, optical disk, and the like.

The RF module 1030 receives the processed data signals from the processing circuit 1010 and converts the data signals into beamformed wireless signals that are then transmitted via the antenna array 1040 and vice versa. The RF module 1030 may include digital-to-analog converters (Digital to Analog Convertor, DACs), analog-to-digital converters (Analog to Digital Converter, ADCs), up-converters (frequency up convertor), down-converters (frequency down converter), filters, and amplifiers for receive and transmit operations. The RF module 1030 may include multiple antenna circuits for beamforming operations. For example, the multi-antenna circuit may include an uplink spatial filter and a downlink spatial filter for shifting the phase of the analog signal or scaling the amplitude of the analog signal. Antenna array 1040 may include one or more antenna arrays.

The apparatus 1000 may optionally include other components such as input and output devices, additional or signal processing circuitry, and the like. Thus, the apparatus 1000 may perform other additional functions, such as executing applications and processing alternative communication protocols.

The processes and functions described herein may be implemented as a computer program that, when executed by one or more processors, causes the one or more processors to perform the corresponding processes and functions. A 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, a computer program may be obtained and loaded into an apparatus, including obtaining the computer program through a physical medium or a distributed system (e.g., a server connected to the internet).

The computer program can be accessible from a computer-readable medium providing program instructions for use by or in connection with a computer or any instruction execution system. The computer-readable medium can comprise any means 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 a 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, removable computer diskette, RAM, ROM, magnetic disk, optical disk and the like. The computer-readable non-transitory storage medium may include all kinds of computer-readable media including magnetic storage media, optical storage media, flash memory media, and solid-state storage media.

While aspects of the invention have been described in conjunction with specific exemplary embodiments, various alternatives, modifications, and variations may be made to these examples. Accordingly, the described embodiments of the present invention are intended to be illustrative only and not limiting. Changes may be made without departing from the scope as set forth in the following claims.

Claims

1. A method of two-stage side link control information, the method comprising:

receiving a transmission block; and

transmitting two-stage side link control information and the transmission block from a transmitting user equipment to a receiving user equipment, wherein the two-stage side link control information comprises first-stage side link control information and second-stage side link control information, and the second-stage side link control information starts from a first physical side link shared channel symbol carrying demodulation reference signals, wherein the first physical side link shared channel symbol carries demodulation reference signals;

the first primary side link control information is transmitted over a physical side link control channel,

the second-stage side link control information and the transport block share resources of a physical side link shared channel, and

and the second-stage side link control information and the transmission block share the demodulation reference signal.

2. The method of two-stage side link control information of claim 1, wherein the step of transmitting the two-stage side link control information and the transport block from the transmitting user equipment to the receiving user equipment comprises:

the second-stage side link control information and the transport block are transmitted using the same transmission scheme with the same one or more antenna ports.

3. The method of two-stage side link control information of claim 1, wherein the step of transmitting the two-stage side link control information and the transport block from the transmitting user equipment to the receiving user equipment comprises:

polarity encoding is applied to the second level side chain control information.

4. The method of two-stage side link control information of claim 1, wherein the first-stage side link control information includes a field for determining a time-frequency location of the second-stage side link control information.

5. The method of two-stage side link control information of claim 1, the method further comprising:

the resource element mapping of the second level side chain control information is performed first in the frequency domain and then in the time domain through the resources of the physical side chain shared channel.

6. The method of two-stage side link control information of claim 1, wherein the first-stage side link control information indicates a modulation and coding scheme used to transmit the transport block.

7. The method of two-stage side link control information of claim 6, the method further comprising:

the resource size of the second-level side link control information is determined based on the indicated modulation and coding scheme used to transmit the transport block.

8. The method of two-stage side link control information of claim 1, wherein the first stage side link control information and the second stage side link control information are multiplexed in different symbols of a time domain or multiplexed in different physical resource blocks of a frequency domain.

9. The method of two-stage side link control information of claim 1, wherein the first-stage side link control information includes information for transmitting an antenna port of the physical side link control channel.

10. The method of two-stage side link control information of claim 1, wherein the first-stage side link control information includes a field indicating whether a demodulation reference signal of the first-stage side link control information is co-located with the second-stage side link control information and the transport block level transmitted through the physical side link control channel.

11. An apparatus for two-stage side-link control information, the apparatus comprising circuitry configured to perform:

receiving a transmission block; and

12. The apparatus of claim 11, wherein the circuit is further configured to perform:

13. The apparatus of claim 11, the circuitry further configured to perform:

14. The apparatus of claim 11, wherein the first stage side link control information comprises a field for determining a time frequency location of the second stage side link control information.

15. The apparatus of claim 11, the circuitry further configured to perform:

16. The apparatus of claim 11, wherein the first primary side link control information indicates information for transmitting a modulation of the transport block and for transmitting an antenna port of the physical side link control channel.

17. The apparatus of claim 16, the circuitry further configured to perform:

18. The apparatus of claim 11, wherein the first level side link control information and the second level side link control information are multiplexed in different symbols of a time domain or multiplexed in different physical resource blocks of a frequency domain.

19. The apparatus of claim 11, wherein the first stage side link control information comprises a field for indicating whether a demodulation reference signal of the first stage side link control information is co-located with the second stage side link control information and the transport block level transmitted over the physical side link control channel.

20. A non-transitory computer readable storage medium storing instructions which, when executed by a processor, perform the steps of the method of two-level side link control information of any one of claims 1-10.