CN112314006A

CN112314006A - Two-stage sidelink control information for sidelink communications

Info

Publication number: CN112314006A
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: 2021-02-02
Anticipated expiration: 2040-04-02
Also published as: WO2020199211A1; CN112314006B

Abstract

A method of two-level Sidelink Control Information (SCI) comprising 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-level SCI may be transmitted through a physical side link control channel (PSCCH). The second level SCI and the transport block may share resources of a physical side link shared channel (pscch). The second-level SCI and the transport block may share a demodulation reference signal (DMRS).

Description

Two-stage sidelink control information for sidelink communications

Cross-referencing

The invention requires the priority of international patent application with the application date of 4 months and 4 days in 2019, the application number of PCT/CN2019/081565 and the name of 2-Stage SCI for V2X Communication, and the priority of Chinese patent application with the application date of 4 months and 3 days in 2019, the application number of 201910296855.6 and the name of 2-Stage SCI for V2X Communication. The contents of the above-mentioned patent applications are incorporated herein by reference in their entirety.

Technical Field

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

Background

This background is provided, in part, to present aspects of the invention in general. 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-all (V2X) (e.g., 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 (called a side-link) can be established between two vehicles. The sidelink may be operated under control of the cellular system (e.g., radio resource allocation) when the vehicle is within the coverage of the cellular system. Alternatively, the sidelink may operate independently when no cellular system is present.

Disclosure of Invention

Aspects of the present invention provide a two-stage (two-stage) Sidelink Control Information (SCI) method. The method comprises the following steps: 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 through a Physical Sidelink Control Channel (PSCCH). The second level SCI and the transport block may share the resources of a physical sidelink shared channel (pscch). The second-level SCI and the transport block may share a demodulation reference signal (DMRS).

In one example, the second-level 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 level SCI. In one example, the first level SCI includes a field for determining a time-frequency location of the second level SCI. In one embodiment, the method further comprises performing (resource element, RE) mapping of the second level sidelink control information first in a frequency domain and then in a time domain over resources of the psch.

In one embodiment, the first level SCI indicates a modulation and coding scheme (MSC) used to transmit the transport block. In one embodiment, the resource size of the second-level SCI may be determined based on the indicated MSC for transmitting transport blocks. In one example, the first-level SCI and the second-level 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 of an antenna port used for transmitting the psch. In one example, the first-level SCI includes fields to indicate whether the DMRS of the first-level SCI is quasi-co-located (QCLed) with the second-level SCI and whether the transport block is transmitted over the psch. 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 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 a Tx UE to an Rx UE. The first-level SCI may be transmitted over the PSCCH. The second level SCI and transport block may share the resources of the pscch. The second-level SCI and the transport block may share the 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-level SCI.

Drawings

The present invention is illustrated by way of example in the following detailed description and is described in reference to the accompanying drawings, in which like references indicate similar elements, and in which:

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

FIG. 2 illustrates an example of a resource pool 200 configured for sidelink communications, according to an embodiment of the present invention;

FIG. 3 shows an example of a two-stage SCI side chain transfer 300 according to an embodiment of the present invention;

FIG. 4 shows another example of a two-stage SCI sidelink transmission 400 according to an embodiment of the present invention;

FIG. 5 shows a scenario where the first-level SCI and the second-level SCI are Time Division Multiplexed (TDM);

FIG. 6 shows a scenario where the first-level SCI and the second-level SCI are Frequency Division Multiplexed (FDM);

FIG. 7 illustrates an example of localized resource allocation in accordance with an embodiment of the present invention;

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

FIG. 9 shows a process 900 for sidelink transmission of a two-stage SCI according to an embodiment of the present invention;

fig. 10 illustrates an exemplary apparatus 1000 according to an embodiment of the present 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. The BS 101 may be an implementation of the gNB specified in the 3GPP NR standard or may be an implementation of the eNB specified in the 3GPP LTE standard. Thus, the BS 101 may communicate with the UE 102 or the UE 103 via the radio interface 110 (referred to as the Uu interface 110) according to the respective wireless communication protocol. Alternatively, the BS 101 may implement other types of standardized or non-standardized radio access technologies and communicate with the UE 102 or the UE 103 according to the respective radio access technologies. UE 102 or UE 103 may be a vehicle, a computer, a mobile phone, a roadside unit (roadside unit), etc.

UEs 102 and 103 may communicate with each other based on the V2X technology specified in the 3GPP standard. A direct radio link, called Sidelink (SL), may be established between UE 102 and UE 103. UE 102 may use the same spectrum for uplink transmission over Uu link 111 and for sidelink transmission over sidelink 120. Similarly, the UE 103 may use the same spectrum for uplink transmissions over the Uu link 112 and sidelink transmissions over the sidelink 120. In addition, BS 101 may control allocation of radio resources on sidelink 120.

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

In some examples, a group of UEs in the local area (e.g., UE 102 and UE 103) may communicate with each other using sidelink, either under control of the base station or without control of the base station. Each UE in the group may periodically or aperiodically send messages to neighboring UEs. 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 sidelink communications 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 (UICC) of the UE 102). Resource pool 200 may be defined by a time/frequency (slot, subchannel) resource grid 210. Radio resources for transmitting physical channels (e.g., PSCCH, pscsch, etc.) from UEs on sidelink 120 may be allocated based on resource pool 200.

As shown, the system bandwidth 201 of the UE 102 includes subchannels #0- # 6. Each subchannel includes a plurality of Physical Resource Blocks (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 the UE 102 operates in a bandwidth part (BWP) 203, the sub-channels of the 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., time slots #0- #4 and #6- #7), which may be contiguous or non-contiguous in different examples.

The UE 102 may be (pre) configured with resource pools from a transmit angle (Tx pool) and a receive angle (Rx pool), respectively. Thus, UE 102 may monitor the PSCCH and thus receive corresponding PSCCH transmissions from other UEs of the Rx pool (e.g., resource pool 200) while transmitting in the Rx pool.

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

Dynamic sidelink grants may be provided in Downlink Control Information (DCI) and resources are scheduled for initial transmission of a transport block and, optionally, for retransmission of the same transport block. The retransmission may be a blind (blindly) repeat transmission 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 be limited to one slot in sidelink resource pool 200.

The scheduling resource may be a set of periodically repeated sidelink resources corresponding to the sidelink configuration grant. The use of side-link configuration authorization 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 sidelink transmissions based on the sensing process. 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 sidelink initial transmission and optional retransmissions. 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 transport blocks or (re-) transmissions based on HARQ feedback. UE 102 may also reserve resources for initial transmission of subsequent transport blocks. The 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) transmitted by the UEs on the PSCCH indicates the selected time-frequency resources that the respective UE uses to transmit the PSCCH. (the indicated time-frequency resources may be allocated in 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., triggered by traffic arrival or resource reselection), the UE 102 considers a sensing window that starts from a past (pre-) configured time and ends shortly before the trigger time. For example, sensing UE 102 also measures the PSSCH-Reference Signal Received 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 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 the transmission is triggered and cannot be longer than the remaining latency budget of the transport block to be transmitted. Based on SCIs from other UEs and measurements as described above, sensing UE 102 excludes selected or reserved resources of other UEs having a psch-RSRP greater than a threshold in a selection window from candidates. The threshold may be set according to a priority of traffic of the sensing UE and other transmitting UEs (e.g., a priority associated with each transport block). Thus, higher priority transmissions from the sensing UE 102 may occupy resources reserved by transmitting UEs with sufficiently low psch-RSRP and sufficiently low priority traffic.

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

Fig. 3 shows an example of a two-stage SCI side link transport 300 according to an embodiment of the present invention. In the sidelink transmission 300, the UE 102 generates and transmits a PSCCH 310 and a PSCCH 320 associated with the PSCCH 310. PSCCH 310 may carry first-level SCI 311, and PSCCH 320 may carry second-level 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 at the physical layer before being mapped to Resource Elements (REs) in a corresponding physical channel (e.g., PSCCH 310 or PSCCH). Such as PSCCH 310 or PSCCH 320). Transport blocks may be received from a higher layer (e.g., a 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 pschs 320.

In one example, the UE 102 may be configured to perform each transmission or retransmission of a transport block or other type of data in one time slot of the time domain. Accordingly, as shown in fig. 3, resources for transmitting the PSCCH 310 and PSCCH 320 may be selected from a pool of Tx resources within one or more subchannels of the time domain and the frequency domain. In one example, one slot may include 14 symbols (e.g., Orthogonal Frequency Division Multiplexing (OFDM) symbols), but may have different durations according to respective subcarrier intervals. 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 PSCCH 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 PSCCH 320.

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

Fig. 4 shows another example of a two-stage SCI side link transport 400 according to an embodiment of the present invention. In the sidelink transmission 400, the UE 102 generates and transmits a PSCCH 410 and a PSCCH 420 associated with the PSCCH 410. PSCCH 410 may carry first-level SCI 411 and PSCCH 320 may carry second-level 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 time slot in the time domain or one or more subchannels in the frequency domain of the Tx resource pool, unlike fig. 3, PSCCH 420 and PSCCH 410 are TDM and FDM.

Further, as shown in fig. 4, the psch 420 may be multiplexed with DMRSs mapped at 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 the 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 level SCI 421 or data 422.

In the examples of fig. 3 and 4, two levels of SCI are used for sidelink transmission. The

corresponding sidelink transmission

300 or 400 may be of the unicast, multicast or broadcast type. During transmission 300/400, first level 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 reachable by first level SCI 311/411). Thus, first level SCI 311/411 may carry information related to channel sensing and be transmitted in a broadcast manner (e.g., low coding rate) so that first level SCI 311/411 may be decoded by all neighboring UEs.

In contrast, second level SCI 321/421 is for UEs involved in unicast or multicast communication (the target UE is a subset of all UEs). Accordingly, the second-level SCI 321/421 may carry information (e.g., a new data indicator and Redundancy Version (RV)) required for decoding the data 322/422 and may be transmitted through 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 level SCI 321/421 to improve spectral efficiency. The high coding rate may be determined based on a 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 level SCI 321/421.

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

In one embodiment, second stage SCI 321/421 may similarly have a fixed size. Link adaptation may be employed to transport second level SCI 321/421 during unicast or multicast communications, 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-level SCI transmission may utilize link adaptation to transmit second-level SCI 321/421, thereby improving spectral efficiency without increasing decoding complexity. In contrast, a single level transmission of SCI with link adaptation will result in blind decoding, increasing decoding complexity.

In some embodiments, multi-antenna transmission is employed. For example, the psch 320/420 in the example of fig. 3 or 4 may 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 so forth. Corresponding to one transmission scheme, one or more antenna ports may be used for transmission of the psch 320/420 (e.g., in multiple layers). Thus, the same transmission scheme and the same antenna port may be used to transmit second level SCI 321/421 and corresponding data 322/422. For transmission on each antenna port, the second-level SCI and corresponding data of the same layer may share the same DMRS, and there is no need to configure a dedicated DMRS 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 psch 320/420. For example, the number of antenna ports (the number of used antenna ports) may be indicated in first stage SCI 311/411. And/or one or more indices of the antenna ports used may be indicated in first stage SCI 311/411. In addition, DMRS patterns (e.g., defining the number and location of DMRS symbols) may be indicated in the first-level SCI 311/411. Different DMRS patterns may be used according to 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-level SCI 311/411, the receiving UE may determine the corresponding DMRS and perform channel estimation, and thus decode the second-level SCI 321/421 and data 322/422 transmitted in the same antenna port as the corresponding DMRS.

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

In one embodiment, first-level SCI 311/411 may include one or more fields to indicate the time-frequency location of corresponding second-level SCI 321/421. For example, first level SCI 311/411 may include a field (e.g., including a code point) that indicates the number of subchannel(s) allocated for transmission of psch 320/420. Additionally, the PSCCH 310/410 may be configured to be located at the bottom of the allocated sub-channel. Thus, the receiving UE may first (depending on the configuration) detect the location of the PSCCH 310/410 in the frequency domain, and then use the information of the allocated sub-channels carried in the first-level SCI to determine the frequency location of the psch 320/420.

In one example, the time-domain location of the respective second-level SCI 321/421 may be determined based on DMRS pattern information carried in the first-level SCI 311/411. For example, as shown in fig. 4, the RE mapping of the second-level SCI 421 may be configured to start from the first DMRS symbol 423A of the psch 420 in the time domain and continue to the next symbol (e.g., symbol 424) adjacent to the first DMRS symbol 423A. Thus, based on such a configuration, a receiving UE may determine the time position of the corresponding second-level SCI 321/421 according to DMRS pattern information carried in the first-level SCI 311/411. In some other examples, the RE mapping of second-level SCI 321/421 may be configured to start 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 psch 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 psch. For example, DMRS symbol 423A is not transmitted in examples with different DMRS patterns. The DMRS symbol 423B becomes the first DMRS symbol. Thus, RE mapping for second-level SCI 421 may start from DMRS symbol 423B.

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

In one example, the UE 102 may perform link adaptation based on the radio link quality of the target channel to send the data 322/422. The radio link quality may be indicated by a Channel Quality Indicator (CQI) provided from the Rx UE. Depending on the radio link quality and with a target error probability (e.g., a block error rate (BLER) of less than 10%), the UE 102 may determine an MCS (or MCS index) for sending the 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.

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

In addition, as described above, the size (number of bits) of the second-level SCI 321/421 may be fixed. Therefore, when determining the coding rate of second level SCI 321/421, the number of bits to send (the number of bits carried in the RE) may be determined. In one embodiment, the modulation level of second stage SCI 321/421 may be pre-configured as Quadrature Phase Shift Keying (QPSK), and thus the REs may carry modulation symbols corresponding to 2 bits. Therefore, the number of REs for transmitting the second-level 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-level SCI and the same psch targets the same SNR level. Thus, the second-level SCI and the link adaptation of 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 qualities). When the psch is transmitted at the UE 102, the MCS used to transmit the data may be first determined, and then the resource size used to transmit the corresponding second-level SCI may be accordingly determined based on a 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, the first level SCI 311/411 may include a field indicating an MCS for transmitting data 322/422. At the receiving UE, based on the mapping relationship as 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-level SCI 311/411 may further include a field indicating a time-frequency start position (e.g., bandwidth and DMRS pattern of the psch 320/420) of the second-level SCI. According to RE mapping rules (frequency domain first, then time domain), resource size, starting location, Rx UE can efficiently determine the REs carrying second level SCI 321/421 in the radio resource grid. Therefore, blind detection of second-level SCI 321/421 can be avoided.

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

In one embodiment, for V2X sidelink communications, the psch may be scheduled by the SCI of the bearer carried in the PSCCH. In one embodiment, the second-level SCI may be used for sensing and broadcasting communication purposes by applying the first-level SCI (or referred to as a first SCI), while the second-level SCI (or referred to as a 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-level SCI and the second-level SCI may be transmitted using either centralized frequency resources or distributed frequency resources. In one embodiment, the first-level SCI and the second-level 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-level SCI may share/use the time/frequency resources reserved for the data channel (e.g., the psch).

The second level SCI may have link adaptation associated with data channel link adaptation. The second-level SCI may have the same transmission scheme as a data channel having the same antenna port or a different transmission scheme having different antenna ports but each resource element has the same power.

In one embodiment, a power boosting may be applied between the sidelink control channel and the data channel. The power offset may be indicated during sidelink Radio Resource Control (RRC) connection setup for unicast/multicast communication, as well as in the first-level SCI.

In one example, the DMRS position in the frequency domain for the first-level SCI may be fixed. The reference signals of the first-level and/or second-level SCIs may reuse/share the data channel (psch) DMRS in whole or in part without a dedicated DMRS for the second-level SCI 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 level SCIs may have their own dedicated DMRSs instead of the data channel DMRSs. The first-level and/or second-level SCI may be channel estimated based on the dedicated DMRS, independently or together with the data DMRS, if the antenna ports and/or transmission schemes of the data and control channels are the same.

The channel coding of the second level SCI may use a polar code. A shorter Cyclic Redundancy Check (CRC) (e.g., a 16-bit CRC) may be applied to the second-level SCI (and/or the first-level SCI) to reduce CRC overhead.

In some examples, whether the DMRS of the first-level SCI and the DMRS of the second-level SCI/data are QCL or whether the same transmission scheme is used based on the same antenna port may be indicated in the first-level SCI. The channel estimation for the second-level SCI/data may then use or 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 the DMRS of the first-level SCI and the DMRS of the second-level SCI) in order to apply the joint channel estimation.

By way of example, table 1 illustrates a comparison between fields of a two-level SCI (including a first-level SCI and a second-level SCI) and a single SCI, in accordance with some embodiments.

TABLE 1

In table 1, the "format indicator" may be 1-bit or more information to indicate whether it is a first-level SCI for scheduling a broadcast message 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 remaining information (e.g., scheduling information for unicast/multicast message reception) will be carried following the second level SCI. 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 the Uu interface or SCI-based unlicensed transmission semi-persistent scheduling (SPS) transmissions similar to the Uu interface or type 2 unlicensed transmissions in Uu interference). In this case, the second-level SCI may not be needed because the detailed scheduling information is already carried in the configuration message by setup or (pre-) configuration. Such a first level SCI for the purpose of sensing a non-granted transmission may be sent periodically based on (pre-) configuration, or may be sent with each data transmission based on the sensing result, for example. It may be transmitted with the data or 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 transmissions, the target UE already knows the data scheduling information based on (pre-) configuration or UE-UE signaling. The first level SCI is then used for sensing purposes only to be decoded by other UEs, not the intended UE. In this case, the second-level SCI is not required, and MCS information in at least the first-level SCI is not required.

The "source/target UE/group ID" may be an 8/16/24-bit field. For broadcast messages or communications, the source/target UE/group ID may not be needed. Meanwhile, the synchronous HARQ is applied to the broadcast transmission by indicating a retransmission time through a "time interval between initial transmission and retransmission" field. For unicast/multicast, due to asynchronous HARQ, the "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, e.g., the initial values for sequence generation may be a function of the target UE/group ID. In the case of unlicensed transmission, the source/target group/UE ID may not be included in the first-level SCI (in which case the second-level SCI may not be needed) because 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 does not require SCI transmission. Alternatively, the target ID may be included in the first-level SCI for unlicensed transmission sensing, which provides the potential to exploit the spatial multiplexing gain through IC for active interference cancellation by multiplexing the same time/frequency resources as the target UE.

"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.

The "resource reservation" is used to indicate/derive time resources to be used for the upcoming transmission.

The "frequency resource location" may be used to indicate the frequency domain resource allocation for data (including second level SCI) transmission, or the frequency offset of the lowest index of the physical resource block (or subchannel) used 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 case of asynchronous HARQ for unicast/multicast, the "time interval between initial transmission and retransmission" may not be needed.

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

The "modulation and coding scheme" may be used to indicate the MCS level of 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, 256QAM) may be indicated in the first-level SCI to derive the target SIN or retransmission.

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

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

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 an aperiodic channel state indicator (a-CSI). The CSI to be measured may be the DMRSs of the first-level SCI, the second-level SCI and/or the data DMRSs occurring at the same time slot of the respective SCI transmission.

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

The "second-level SCI T/F location" indicates the time/frequency location of the second-level SCI.

The "reserved bits" may be used in the future or determined later (TBD).

The "CRC" field is used to carry CRC bits. The scrambling may be further 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 a 24-bit ID, all 24 bits may be scrambled in the CRC of the second-level SCI. Alternatively, at the end of a 16-bit CRC of a 24-bit CRC, only the 16 bits of the (most or least) ID may be scrambled. The remaining 8 bits of the ID may be carried explicitly in the payload of the second level 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) Different sized fields of the second level 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-level SCI indicated by the "second-level SCI T/F location" may be interpreted differently according to different SCI sizes. (3) A field indicating the first-level SCI, the second-level SCI, and/or a starting symbol of data transmission. (4) A field indicating the lowest PRB index of 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-level SCI and the second-level SCI may use either centralized frequency resources or distributed frequency resources for transmission. The first-level SCI and the second-level SCI may be time-domain multiplexed in different symbols and/or frequency-domain multiplexed in different PRBs (interleaved or non-interleaved). The second-level SCI may share/use the time/frequency resources reserved for the corresponding data channel.

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

FIG. 6 shows another scenario where the first-level SCI and the second-level SCI are FDMs. 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 level SCI to explicitly indicate the second level SCI location. Each code point (or entry) may indicate one of the predefined time/frequency positions of the second-level SCI in the mapping table.

In one embodiment, the second level SCI position 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 for data transmission. For example, the modulation to be used for the data may determine a target SINR level. Assuming that the payload size of the second-level SCI is fixed, the resource size (e.g., the 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 a target SINR/SNR level may be used to determine the 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-level SCIs are mapped with different modulation levels indicated in the first-level SCIs.

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 the starting symbol and/or lowest index of the PRBs of the second level SCI, or a (pre-) configuration of a relative/fixed offset in time/frequency domain with respect to the 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 level SCI is selected from a set of values that approximate the data or sub-channel bandwidth. For example, for a second level SCI bandwidth, using a set of values {12, 24, 48, 96} RB, and representing the data transfer 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. Also, PRB _ Offset can be used as a limit, e.g., close to but less than Data BW _ PRB-PRB _ Offset. Such PRB _ Offset can be used to leave PRB _ Offset/2 PRBs at each edge of the bandwidth and protect the second level SCI from in-band emission interference. Such PRB _ Offset may be (pre-) configured by the base station or UE. Further based on the total number of selected bandwidth and resource sizes, the number of symbols in the time domain can be determined accordingly as:

number of symbols round down (floor) (total number of RBs/number of RBs per symbol) or round up (ceiling) (total number of RBs/number of RBs per symbol)

Table 3 and table 4 together show an example of determining an MCS for data transmission based on field combinations in the first-level SCI and the corresponding second-level SCI.

TABLE 3

Table 4 shows an example of a modulation scheme, Transport Block Size (TBS) index and redundancy version table for the SL data channel.

TABLE 4

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 both the resources (size) for the second level SCI and a portion of the MCS information for data transmission. Table 5 shows an example of a modulation, TBS index, and redundancy version table for the SL data channel based on a combination of fields in the first-level SCI and the second-level SCI.

TABLE 5

Similarly, if MCS index ranges are used instead of modulation levels, resources (sizes) for the second level SCI may be derived. Table 6 shows an example table indicating a mapping between MCS index ranges and resources (sizes) of the second-level SCIs.

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) that can be carried in the first-level SCI. In case of different layers (or different numbers of antenna ports) for (second level SCI) transmission, the corresponding resources (size) 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. Due to the multi-layer transmission, the more layers of the second layer SCI, the smaller the size of each layer.

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

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) for the side link control channel can be calculated by:

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

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

In one embodiment, the resource elements are first mapped in the frequency domain and then mapped in the time domain based on the principle that the same number of PRBs are in each symbol. Further, the number of RBs in each symbol is equal to or less than the data/subchannel/BWP bandwidth. There may be PRB _ offset at the edge of the data or subchannel to derive the starting PRB of the control channel.

FIG. 7 illustrates an example of localized resource allocation in accordance with an embodiment of the present invention. As shown, the number of symbols X may be determined by satisfying the condition with the 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 subchannel or BWP and PRB _ Offset is the spacing or margin relative to the (two) edges of the data or subchannel. The starting PRB index of the control channel within the data or sub-channel region may be PRB Offset relative to the lowest index of the data or sub-channel RB.

Alternatively, the control channel may be located at the center of the data or sub-channel region, e.g., the RBs for the control channel are determined to be 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 control channel previously derived and referrepoint may be zero or (pre) configured, e.g. the edges of (allocated/scheduled) data, sub-channels or bandwidth parts, for deriving the absolute RB index.

Fig. 8 shows an example of a 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, the 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 portion of the region in fig. 4) { LowestRBIndex, HighestRBIndex } - { referencePoint + PRB _ Offset, referencePoint + PRB _ Offset + ceiling (L _ RBs/2) }, and

region 1 (i.e., the lower portion of the region in fig. 4) { lowerstrbindex, HighestRBIndex } - { referrenepoint + M _ RBs-PRB _ Offset-ceiling (L _ RBs/2), referrenepoint + M _ RBs-PRB _ Offset }.

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

In one embodiment, the DMRS position in the frequency domain for the first-level SCI may be fixed. The reference signals of the first-level and/or second-level SCIs may reuse/share the data channel (psch) DMRS in whole or in part without a dedicated DMRS for the second-level SCI 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 level SCIs may have their own dedicated DMRSs instead of the data channel DMRSs. The first-level and/or second-level SCI may be channel estimated based on the dedicated DMRS, independently or together with the data DMRS, if the antenna ports and/or transmission schemes of the data and control channels are the same.

In one embodiment, a field in the first and/or second level SCI may indicate that SCI 311/411 may be used to indicate that the first level SCI DMRS and the second level 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 may 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 the DMRS of the first-level SCI and the DMRS of the second-level SCI) in order to apply the joint channel estimation.

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

Fig. 9 illustrates an example process 900 for sidelink transmission of a two-stage SCI according to an embodiment of the invention. Process 900 may begin at S901 and proceed to S910.

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

At S920, the transport block may be processed at the physical layer and transmitted from the Tx UE to the Rx UE. Two-level SCIs including a first-level SCI and a second-level SCI may be used for the transmission. The first-level SCI may be transmitted over the PSCCH. The second level SCI and transport block may share the radio resources allocated to the psch. The second-level SCI and the transport block may share the DMRS. No dedicated DMRS is transmitted for the second level SCI. The process 900 proceeds to S999 and ends at 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 implementations or examples herein. Thus, the device 1000 may provide a means to implement 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 circuitry for performing 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, the processing circuitry 1010 may include circuitry configured to perform the functions and processes described herein, which may or may not be implemented in combination with software. In various examples, the processing Circuit may be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Programmable Logic Device (PLD), a Field Programmable Gate Array (FPGA), a Digital enhanced Circuit (Digital enhanced Circuit), or a comparable Device or combination thereof.

In some other examples, the Processing circuitry 1010 may be a Central Processing Unit (CPU) configured to execute program instructions to perform various functions and processes described herein. Accordingly, the memory 1020 may be configured to store program instructions. When executing program instructions, 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 (RAM), flash Memory, solid state Memory, a hard disk, an optical disk, and the like.

The RF module 1030 receives processed data signals from the processing circuitry 1010, converts the data signals into beamformed wireless signals, and then transmits via the antenna array 1040, and vice versa. The RF module 1030 may include a Digital-to-Analog Converter (DAC), an Analog-to-Digital Converter (ADC), an up-Converter (frequency up Converter), a down-Converter (frequency down Converter), a filter, and an amplifier for receiving and transmitting operations. The RF module 1030 may include a multi-antenna circuit for beamforming operation. 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. The 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. Accordingly, device 1000 may perform other additional functions, such as executing applications and handling alternative communication protocols.

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

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

Although aspects of the present invention have been described in conjunction with specific exemplary embodiments, various alternatives, modifications, and variations may be possible with respect to these examples. Accordingly, the described embodiments of the invention are intended to be illustrative rather than restrictive. Changes may be made without departing from the scope as set forth in the claims.

Claims

1. A method, the method comprising:

receiving a transmission block; and

transmitting two-stage side link control information and the transport 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;

transmitting the first level sidelink control information over a physical sidelink control channel,

the second level sidelink control information and the transport block share resources of a physical sidelink shared channel, and

the second level sidelink control information and the transmission block share a demodulation reference signal.

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

transmitting the second level sidelink control information and the transport block using a same transmission scheme having a same one or more antenna ports.

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

applying a polarity encoding to the second level sidelink control information.

4. The method of claim 1, wherein the first level sidelink control information comprises a field for determining a time frequency location of the second level sidelink control information.

5. The method of claim 1, the method further comprising:

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

6. The method of claim 1, wherein the first level sidelink control information indicates a modulation and coding scheme used for transmitting the transport block.

7. The method of claim 6, the method further comprising:

determining a resource size of the second level sidelink control information based on the indicated modulation and coding scheme for transmitting the transport block.

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

9. The method of claim 1, wherein the first level sidelink control information comprises information for an antenna port used to transmit the physical sidelink control channel.

10. The method of claim 1, wherein the first level sidelink control information comprises a field for indicating whether a demodulation reference signal of the first level sidelink control information is quasi co-located with the second level sidelink control information and the transport block sent over the physical sidelink control channel.

11. An apparatus, wherein the apparatus comprises 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:

applying a polarity encoding to the second level sidelink control information.

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

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

16. The apparatus of claim 11, wherein the first level sidelink control information indicates a modulation used to send the transport block and information for an antenna port used to send the physical sidelink 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 in a time domain or are multiplexed in different physical resource blocks in a frequency domain.

19. The apparatus of claim 11, wherein the first level sidelink control information comprises a field to indicate whether a demodulation reference signal of the first level sidelink control information is quasi co-located with the second level sidelink control information and the transport block sent over the physical sidelink control channel.

20. A non-transitory computer readable storage medium storing instructions that, when executed by a processor, perform a method comprising:

receiving a transmission block; and