CN112616191A

CN112616191A - Method for enhancing logical channel prioritization for sidelink transmission and transmitter user equipment

Info

Publication number: CN112616191A
Application number: CN202011055602.9A
Authority: CN
Inventors: 林冠宇
Original assignee: MediaTek Inc
Current assignee: MediaTek Inc
Priority date: 2019-10-03
Filing date: 2020-09-30
Publication date: 2021-04-06

Abstract

An enhanced method for logical channel prioritization for sidelink transmissions and a transmitter user equipment method are presented to avoid resource starvation. When allocating SL resources to a new MAC PDU for SL transmission, the TX UE prioritizes RX UEs having at least one SL LCH that does not meet the required minimum bit rate during target UE selection. The TX UE maintains a value Bj for each SL LCH j, where Bj >0 indicates that the logical channel does not meet the priority bit rate requirement. If at least one target UE owns a SL LCH with data available for transmission and with Bj >0, the selected target UE is the UE with the highest priority SL LCH with data available for transmission and with Bj > 0.

Description

Method for enhancing logical channel prioritization for sidelink transmission and transmitter user equipment

Cross Reference to Related Applications

Priority of the present application, in accordance with U.S. provisional application No. 62/909,837 entitled "enhancement of logical channel prioritization for sidelink transmission" filed 2019, 10/3/35 u.s.c § 119, the subject matter of which is herein incorporated by reference.

Technical Field

The disclosed embodiments relate generally to wireless network communications and, more particularly, to Logical Channel Prioritization (LCP) procedure enhancements for sidelink transmissions in a 5G New Radio (NR) vehicle networking (V2X) wireless communication system.

Background

Third generation partnership project (3 GPP) and Long Term Evolution (LTE) mobile telecommunication systems provide high data rates, lower latency and improved system performance. In a 3GPP LTE network, an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of base stations, e.g., evolved Node bs (enbs), which communicate with a plurality of mobile stations called User Equipments (UEs). Orthogonal Frequency Division Multiple Access (OFDMA) has been selected as the LTE Downlink (DL) radio Access scheme because of its robustness to multipath fading, higher spectral efficiency and bandwidth scalability. Multiple access in the downlink is achieved by allocating different sub-bands of the system bandwidth, i.e., groups of sub-carriers, denoted as Resource Blocks (RBs), to individual users based on their existing channel conditions.

To meet this exponentially growing demand in communications, additional spectrum (i.e., radio spectrum) is required. The number of licensed spectrum is limited. Accordingly, communication providers are looking for unlicensed spectrum to meet the exponential growth of communication demand. The first communication link may be provided using an established communication protocol (e.g., 4G LTE and 5G NR) over a licensed spectrum and the second communication link may also be provided using LTE/NR over an unlicensed spectrum. In New Radio-Unlicensed (NR-U), any downlink and uplink access must follow the listen-before-talk (LBT) channel access procedure, since other networks (e.g., WiFi) also use Unlicensed frequencies.

For UEs within coverage, the base station may schedule data traffic on the Uu link. For out-of-coverage UEs, the UE may schedule data traffic through the PC5 (or sidelink). Compared to WiFi and NR unlicensed spectrum operation, a PC5 link (or sidelink) based mobile device may have the following features: 1) both operators and users can deploy; 2) operable in both unlicensed and licensed spectrum; 3) protocol stack complexity similar to WiFi; 4) better multiplexing efficiency than WiFi; 5) better mobility support than WiFi, such as service continuity; 6) the maximum transmission power is larger than that of WiFi, and the coverage area is larger; 7) multi-hop relaying is supported.

There are potential problems in the current LTE V2X design with sidelink transmission. First, there may be resource starvation between target UEs. In LTE V2X, a Transmitter (TX) UE always selects a target UE with the highest priority sidelink logical channel (SL LCH) and the SL LCH has data that can be transmitted between multiple Receiver (RX) UEs. However, if such LTE V2X design for target UE selection is directly applied, there is a problem of resource starvation between target UEs. That is, the target UE with the highest priority SL LCH may always occupy the entire MAC PDU of the transmitter UE (SL grant) regardless of how much SL data the transmitter UE sent for the high priority SL LCH in the previous MAC PDU. This means that other target UEs without the highest priority SL LCH cannot be scheduled (i.e. resource starved) by the transmitter UE with any SL transmission until the transmitter UE sends all data of the highest priority SL LCH. Second, multiple communication ranges are not supported. In NR V2X, various V2X applications are supported. Different minimum communication ranges are supported based on the application. If a UE is configured with a large SL grant, the UE may not be able to send a large SL grant with large coverage due to power limitations in the sidelink. In other words, for some V2X applications that require a larger communication range (i.e., wider coverage), the applicable SL grant cannot be too large, i.e., a limit is required to ensure that the minimum communication range is met. Currently, this limitation has not been considered in the SL resource allocation process. Third, there is a problem of Hybrid Automatic Repeat reQuest (HARQ) collision. In mixed mode operation, both the Network (NW) and the UE may select SL resources for transmission. Each new SL grant transmission is associated with a HARQ process for the new transmission and retransmission. Since there is no coordination between the NW and the UE scheduler, the NW and the UE may perform SL transmission for the same target UE and the same HARQ process ID. It is not clear how to handle HARQ collisions.

A solution is sought.

Disclosure of Invention

In order to avoid resource shortage, an enhanced method for logical channel prioritization for sidelink transmission and a transmitter user equipment are provided. When allocating SL resources to a new MAC PDU for SL transmission, the TX UE prioritizes RX UEs having at least one SL LCH that does not meet the minimum required bit rate during target UE selection. The TX UE maintains a value Bj for each SL LCH j, where Bj >0 indicates that the logical channel does not meet the priority bit rate requirement. If at least one target UE owns a SL LCH with data available for transmission and with Bj >0, the selected target UE is the UE with the highest priority SL LCH with data available for transmission and with Bj > 0. Otherwise, the selected target UE is the UE with the highest priority SL LCH with data available for transmission (i.e., Bj < ═ 0).

In one embodiment, a transmitter UE establishes a plurality of SL LCHs for NR SL communication. The plurality of SL LCHs store SL data to be sent to a plurality of receiver UEs. The transmitter UE maintains an indicator for each SL LCH for each receiver UE. Each indicator indicates whether the corresponding SL LCH with available SL data has met the minimum required bit rate to guarantee the QoS requirements for the corresponding SL LCH. The transmitter UE selects a target UE from the plurality of receiver UEs based on both the indicator value and the SL LCH priority for each SL LCH of each receiver UE. The transmitter UE transmits the MAC PDU to the selected target UE through the SL resource. SL resources are allocated to construct MAC PDUs by multiplexing SL data from different SL LCHs for selected target UEs.

Other embodiments and advantages are described in the detailed description that follows. This summary is not intended to define the invention. The invention is defined by the claims.

Drawings

Figure 1 illustrates an enhanced wireless communication system supporting LCP for a side link, in accordance with novel aspects.

Figure 2 is a simplified block diagram of a wireless transmitting device and a receiving device in accordance with the novel aspects.

Figure 3 illustrates a sequence flow between a network and transmitter and receiver UEs for LCP process enhancement, in accordance with one novel aspect.

Figure 4 illustrates a first embodiment of target UE selection during an LCP procedure, in accordance with one novel aspect.

Figure 5 illustrates a second embodiment of target UE selection during LCP procedures in accordance with one novel aspect.

Figure 6 is a flow chart of a method of LCP for a side link in accordance with one novel aspect.

Detailed Description

Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.

Figure 1 illustrates a wireless communication system 100 in accordance with one novel aspect, the wireless communication system 100 supporting enhancements to LCP for side-links. The 5G NR mobile communication network 100 includes a 5G core (5G core, 5GC)101, a base station gsnodeb 102, and a plurality of user equipments UE 103, UE 104, and UE 105. For a plurality of UEs within the coverage, for example, UE 103, the base station may schedule a sidelink resource through the Uu link for the UE to perform sidelink communication (i.e., network scheduling); alternatively, in another resource allocation mode, the UE may select sidelink resources for its transmission (i.e., UE autonomous scheduling). For multiple out-of-coverage UEs, such as UE 104, the UE can only select resources for sidelink communications by itself since scheduling from the base station is not available.

In LTE and NR networks, a Physical Downlink Control Channel (PDCCH) is used for Downlink (DL) scheduling or Uplink (UL) scheduling transmission of a Physical Downlink Shared Channel (PDSCH) or a Physical Uplink Shared Channel (PUSCH). DL/UL scheduling information carried by the PDCCH is referred to as Downlink Control Information (DCI). The DCI format is a predefined format in which downlink control information is formed and transmitted in a PDCCH. Similarly, a Physical Sidelink Control Channel (PSCCH) is used for SL scheduling of Physical Sidelink Shared Channel (PSCCH) transmissions. The sidelink scheduling information carried by the PSCCH is called Sidelink Control Information (SCI). The SCI is sent from the TX UE to the RX UE over the sidelink. The SCI format is a predefined format in which sidelink control information is formed and transmitted in the PSCCH. Both the DCI format and the SCI format provide UE scheduling details such as the number of resource blocks, resource allocation type, modulation scheme, transport block, redundancy version, coding rate, etc.

When the TX UE creates a MAC PDU to transmit using the allocated radio resource, the TX UE satisfies QoS of each configured radio bearer. The TX UE must decide the amount of data for each LCH to be included in the MAC PDU. In constructing a MAC PDU with data from multiple LCHs, data from the highest priority LCH is first provided in the MAC PDU, then data from the next highest priority LCH until the MAC PDU space is exhausted. In LTE, a Prioritized Bit Rate (PBR) is defined for each LCH to transmit data in order of importance, and low priority data starvation is also avoided. PBR is the minimum data rate guaranteed by LCH. Even if a logical channel has a lower priority, it is allocated at least a small amount of MAC PDU space to guarantee PBR of the low priority logical channel. In the conventional LCP procedure in NR Uu, each LCH j has a value Bj that is incremented by the time PBR since the last Bj update. The conventional LCP procedure for resource allocation of SL LCH includes two rounds: first round-allocating resources to satisfy Bj (from high priority SL LCH to low priority SL LCH) according to decreasing order of priority; second round-allocating resources according to decreasing order of priority to clear all remaining data from it until the SL resource granted by the SL is exhausted or no SL LCH owns the remaining data. SL LCHs configured with the same priority should serve equally.

In LTE V2X, the UE is configured with one of two resource allocation modes, i.e. transmission resources are scheduled by the NW or selected by the UE itself. In NR V2X, the UE is able to handle two resource allocation patterns simultaneously. That is, the UE may use the NW scheduled resources for (re) transmission and at the same time perform other transmissions based on the resources selected by the UE itself (e.g., randomly selecting resources from a resource pool configured by the NW). In LTE V2X, the transmitter UE needs to send SL data to multiple receiver UEs, and therefore needs to select a target UE when constructing a new MAC PDU. Typically, the target UE is selected in LTE V2X by comparing the highest priority of the SL LCH with the data available for transmission. However, if such a conventional LTE V2X design for target UE selection is directly applied in the NR V2X design, there is a problem of resource starvation between target UEs. That is, a target UE with a high priority SL LCH can always occupy the entire new MAC PDU, regardless of how much SL data has been sent for the high priority SL LCH in the previous MAC PDU.

According to one novel aspect, a method of prioritizing SL LCHs for LCP procedures in NR V2X during target UE selection is proposed to avoid resource starvation. In the example of fig. 1, UE 103 is a TX UE for transmitting MAC PDUs over SL resources, and UE 104 and UE105 are RX UEs. When constructing the MAC PDU, TX UE 103 prioritizes SL LCHs according to Bj values during target UE selection. In a first example, SL LCHs with Bj > Bth take precedence over SL LCHs with Bj < ═ Bth. In a second example, SL LCHs with Bj > ═ Bth take precedence over SL LCHs with Bj < Bth. Bth is any value or positive or non-negative value that can be configured for each UE or each SL LCH. In general, indicator Bj >0 indicates that the LCH has not yet met the minimum required bit rate, so UEs having at least one SL LCH with Bj >0 have precedence over UEs not having a SL LCH with Bj > 0. For example, if at least one UE possesses a SL LCH with data available for transmission and with Bj >0, the target UE is the UE possessing the highest priority SL LCH with data available for transmission and with Bj > 0. Otherwise, the target UE is the UE with the highest priority SL LCH with data available for transmission.

Figure 2 is a simplified block diagram of a wireless device 201 and a wireless device 211 in accordance with the novel aspects. For a wireless device 201 (e.g., a base station or relay UE),

antennas

207 and 208 transmit and receive radio signals. An RF transceiver 206, coupled to the antenna, receives RF signals from the antenna, converts them to baseband signals, and sends the baseband signals to the processor 203. The RF transceiver 206 also converts a baseband signal received from the processor, converts it into an RF signal, and transmits it to the antenna 207 and the antenna 208. The processor 203 processes the received baseband signals and invokes different functional blocks and circuits to perform functions in the wireless device 201. The memory 202 includes volatile and non-volatile computer-readable storage media and stores program instructions and data 210 to control the operation of the wireless device 201.

Similarly, for wireless device 211 (e.g., a remote user device), antenna 217 and antenna 218 transmit and receive RF signals. The RF transceiver 216 is coupled to the antenna, receives an RF signal from the antenna, converts it into a baseband signal, and sends the baseband signal to the processor 213. The RF transceiver 216 also converts a baseband signal received from the processor into an RF signal, and transmits the RF signal to the antenna 217 and the antenna 218. The processor 213 processes the received baseband signals and invokes different functional blocks and circuits to perform functions in the wireless device 211. Memory 212 includes volatile and non-volatile computer-readable storage media and stores program instructions and data 220 to control the operation of wireless device 211.

The wireless device 201 and the wireless device 211 also include several functional modules and circuits that may be implemented and configured to perform embodiments of the present invention. In the example of fig. 2, the wireless device 201 is a repeater or TX UE that includes a protocol stack 222, resource management circuitry 205 for allocating and scheduling sidelink resources, LCP processing circuitry 204 for performing SL LCP with target UE selection, connection processing circuitry 209 for establishing sidelink connections and logical channels with remote UEs, and control and configuration circuitry 221 for providing control and configuration information. The wireless device 211 is a remote or RX UE that includes a protocol stack 232, synchronization processing circuitry 215, relay discovery circuitry 214 for discovering relay UEs, connection processing circuitry 219 for establishing sidelink connections, and configuration and control circuitry 231. The various functional blocks and circuits may be implemented and configured by software, firmware, hardware or any combination thereof. When the functional modules and circuits are executed by the processor 203 and the processor 213 (e.g., by executing the program code 210 and the program code 220), the relay UE 201 and the remote UE 211 are allowed to perform embodiments of the present invention accordingly. In one example, UE 201 is a TX UE that performs a sidelink LCP procedure for sidelink transmission via LCP processing circuitry 204. The transmitter UE selects the target UE with the highest priority SL LCH with indicator Bj >0 (i.e. the minimum required bit rate is not met) among all receiver UEs.

Figure 3 illustrates the sequence flow between the network 301 and the transmitting TX UE302 and the receiving RX UE 303 305 for LCP procedure enhancements in accordance with one novel aspect. In step 311, the network 301 establishes a connection with the TX UE302 over the Uu link. At step 312, the TX UE302 receives various broadcast and unicast information from the network, including scheduling information and resource allocation. Note that the base station may schedule sidelink resources over the Uu link to enable the UE to perform sidelink communications (i.e., network scheduling). Alternatively, the UE may select sidelink resources for its own transmissions for V2X (i.e., UE autonomous scheduling). In step 313, the TX UE302 establishes a PC5-RRC connection with the other RX UEs 303-305. Note that if the TX UE is performing a broadcast of V2X, the TX UE does not have to establish any SL connection with the RX UE before sending data. For V2X communication and QoS management, multiple sidelink radio bearers (SL RBs) may be established and each SL RB mapped to a different SL LCH. Further, each SL RB maps to one or more QoS flows that define the QoS requirements of the SL LCH. One of the QoS requirements includes a minimum required bit rate or PBR per SL LCH.

The sidelink LCP procedure will be applied whenever a new transfer is performed. RRC layer signaling controls the scheduling of sidelink data by sending the following signaling for each logical channel: sl-Priority, where an increase in Priority value indicates a lower Priority; sl-Prioritized Bit Rate for setting a sidelink Prioritized Bit Rate (sPBR); and sl-bucketSizeDuration for setting a sidelink Bucket Size Duration (sBSD). The RRC layer additionally sends the following signaling to control the LCP procedure by configuring mapping restrictions for each logical channel: sl-configurable slgranttype1Allowed, setting whether the configured one or more grant types 1 can be used for sidelink transmission; sl-allowedCG-List, setting one or more grants of allowed configurations for sidelink transmissions. A UE variable Bj maintained at the TX UE side of each logical channel j and used for the logical channel prioritization procedure.

In step 321, the TX UE302 performs a sidelink LCP procedure for the new transmission. In NR V2X, when a TX UE performs a new transmission to multiple RX UEs through a sidelink, the TX UE302 needs to construct a new MAC PDU from the different logical channels of each RX UE. Therefore, prior to the LCP procedure of allocating resources based on LCH priority to meet QoS requirements, the TX UE also needs to select a target UE from the multiple RX UEs for side link resource allocation. Typically, the target UE is selected in LTE V2X by comparing the highest priority of the SL LCH with data available for transmission between multiple receiver UEs. However, there is a problem of resource scarcity among a plurality of target UEs. That is, the target UE with the highest priority SL LCH can always occupy the entire new MAC PDU (SL grant) of the transmitter UE, regardless of how much SL data the transmitter UE has sent for the highest priority SL LCH in the previous MAC PDU.

According to one novel aspect, in step 322, an enhanced sidelink LCP procedure is performed by the UE302 with target UE selection to avoid resource starvation among multiple RX UEs. Specifically, the enhanced side-chain LCP process includes the following steps. First, TX UE302 maintains a variable Bj value for each logical channel j for each RX UE. Second, TX UE302 selects a target UE among the plurality of RX UEs based on the maintained Bj. Third, TX UE302 selects a sidelink LCH from the selected target UEs for resource allocation. Finally, TX UE302 constructs a MAC PDU based on the target UE selection and sidelink LCH resource allocation. In step 331, the TX UE302 sends the constructed MAC PDU to the RX UE 303 via sidelink transmission 305.

The variable Bj is maintained by the TX UE for each logical channel j of each RX UE as follows:

bj min (Bj + sPBR T, storage size)

Bj-scheduling data

Specifically, when a logical channel is established, the MAC entity in the TX UE initializes Bj of the logical channel to zero. For each logical channel j, the MAC entity multiplies Bj by the sPBR × T product before each instance of the LCP procedure, where sPBR is the side link priority bit rate and T is the elapsed time since the last increment of Bj. If the value of Bj is greater than the side link memory region size (i.e., sPBR), then Bj is set to the side link memory region size. Note that the exact moment the UE updates Bj between LCP procedures depends on the UE implementation, as long as Bj is up-to-date when LCP handles authorization. After scheduling the data, then Bj ═ Bj — scheduled data. In general, the value of Bj indicates whether LCH j meets the minimum bit rate required to guarantee QoS requirements. If Bj >0, this indicates that SL LCH j has not yet met the minimum required bit rate; if Bj < ═ 0, it indicates that SL LCH j has reached the minimum required bit rate.

Based on the maintained Bj values, TX UE302 may perform selection for the target UE accordingly. When constructing the MAC PDU, TX UE302 prioritizes SL LCHs according to Bj values during target UE selection. Generally, SL LCHs with Bj > Bth take precedence over SL LCHs with Bj < ═ Bth. Optionally, SL LCHs with Bj > ═ Bth take precedence over SL LCHs with Bj < Bth. Note that Bth is any value or positive or non-negative value that can be configured for each UE or for each SL LCH. Selecting the target UE if the target UE has a logical channel with the highest priority among logical channels satisfying all of the following conditions: 1) SL data may be available for transmission; 2) if any logical channel has Bj >0, then Bj > 0; and 3) if the SL grant is a configured grant type1, then set SL-configurable SLGrantType1Allowed to true (e.g., if configured). For example, if at least one target UE possesses a SL LCH with data available for transmission and Bj >0, then the target UE is the UE possessing the highest priority SL LCH with data available for transmission and Bj > 0; otherwise, the target UE is the UE with the highest priority SL LCH with data available for transmission (i.e., Bj < ═ 0).

Table 400 of figure 4 illustrates a first embodiment of target UE selection during an LCP procedure, in accordance with one novel aspect. In the example of fig. 4, the transmitter UE has two target UEs: UE1 and UE 2. Towards UE1, the transmitter UE has three sidelink logical channels LCH1, LCH2, and LCH3 with SL LCH priorities of 1, 2, and 3, respectively. For UE2, the transmitter UE has two logical channels LCH1 and LCH2 with SL LCH priorities of 1 and 2, respectively. During target UE selection, the SL LCH will be classified as Bj >0 and Bj < 0. SL LCHs with Bj >0 take precedence over SL LCHs with Bj < 0. Thus, the first category priority group (Bj >0) includes LCH3 of UE1 having SL LCH priority of 3, and LCH2 of UE2 having SL LCH priority of 2. The second category priority group (Bj <0) includes LCHs 1 of UEs 1 having SL LCH priority of 1. The TX UE compares the class priority first and then compares the SL LCH priority for the same class. Since the UE2 has the highest priority SL LCH2 with SL LCH priority 2 in the first priority class (Bj >0), the UE2 is selected as the target UE and SL licenses are assigned to the multiple SL LCHs of the UE2, namely SL LCH1 and SL LCH2 of the UE 2. Note that a lower LCH priority value corresponds to a higher priority.

Figure 5 illustrates a second embodiment of target UE selection during LCP procedures in accordance with one novel aspect. In the example of fig. 5, the TX UEs are three RX UEs: UE1, UE2, and UE3 maintain separate TX buffers. Each RX UE has two side link logical channels: SL LCH1 and SL LCH 2. In the enhanced sidelink logical channel prioritization procedure, the TX UE should select one UE as the target UE to allocate SL resources for SL transmission. Thus, TX UEs prioritize RX UEs whose associated SL LCHs have Bj >0, i.e., prioritize those SL LCHs that do not meet their minimum required bit rate, regardless of the priority of the SL LCHs having available data for the SL. As shown in fig. 5, LCH1 and LCH2 of RX UE1 both have Bj >0, e.g., the minimum bit rate has not been met; LCH1 and LCH2 of RX UE2 both have Bj <0, e.g., amounts of bits other than those minimum required bit rates; and LCH1 and LCH2 of RX UE3 both have Bj >0, e.g., the minimum bit rate has not been met. As a result, RX UE2 is excluded from being selected as the target UE because RX UE2 does not have SL LCHs with Bj > 0. RX UE1 and RX UE3 both possess SL LCHs with Bj >0 and are therefore considered target UE selections. The TX UE selects the UE having the highest priority SL LCH with Bj >0 among UE1 and UE3 as the target UE. If UE1 and UE3 have the same highest priority SL LCH with Bj >0, then depending on the UE implementation, which UE is selected from UE1 and UE3 as the target UE.

For example, if SL LCH1 and SL LCH2 towards RX UE1 have SL LCH priorities of 1 and 2, respectively, and if SL LCH1 and SL LCH2 towards RX UE2 have SL LCH priorities of 2 and 3, respectively, then the transmitter UE will select RX UE1 as the target UE, since RX UE1 has the highest priority SL LCH, and has data available for transmission and Bj > 0. After determining the target UE, the transmitter UE then performs a SL data multiplexing procedure to stuff data of the SL LCH of the target UE into the SL MAC PDU. In the first round of resource allocation, the transmitter UEs allocate resources to satisfy Bj of SL LCH1 and SL LCH2 (in descending order of SL LCH priority). Note that SL LCH1 should be scheduled earlier than SL LCH2 because SL LCH1 has a higher SL LCH priority than SL LCH 2.

The resources that meet the prioritized bit rate requirements of SL LCH1 and SL LCH2 are shown in fig. 5 as

blocks

1 and 2, respectively. After the first round of resource allocation, if there are still remaining SL grant sizes to accommodate more SL data, the transmitter UE performs a second round of resource allocation: starting from the highest priority SL LCH of the selected target UE (RX UE1), the transmitter UE allocates resources to each SL LCH in descending order of SL LCH priority (regardless of Bj value) until each SL LCH has no data remaining or until the remaining SL grant sizes are exhausted. Blocks 3 and 4 are the resources of SL LCH1 and SL LCH2 of the selected RX UE1 allocated in the second round of resource allocation. As a result, the SL MAC PDU is sent to RX UE1, and the MAC PDU includes data from SL LCH1 (i.e., allocated resources (in bytes) block 1 plus block 3) and data from SL LCH2 (i.e., allocated resources (in bytes) block 2 plus block 4).

Figure 6 is a flow chart of a method of LCP for a side link in accordance with one novel aspect. In step 601, the transmitter UE establishes a plurality of SL LCHs for NR SL communication. The plurality of SL LCHs store SL data to be sent to a plurality of receiver UEs. At step 602, the transmitter UE maintains an indicator for each SL LCH for each receiver UE. Each indicator indicates whether the corresponding SL LCH with available SL data has met the minimum required bit rate to guarantee the QoS requirements for the corresponding SL LCH. In step 603, the transmitter UE selects a target UE from the plurality of receiver UEs based on both the indicator value and the SL LCH priority for each SL LCH of each receiver UE. In step 604, the transmitter UE transmits the MAC PDU to the selected target UE through the SL resource. SL resources are allocated to construct a MAC PDU by multiplexing SL data from multiple different SL LCHs for the selected target UE.

In one embodiment, the TX UE performs SL LCP for sidelink transmission as follows. SL LCHs with Bj above the threshold (e.g., positive Bj) are prioritized over SL LCHs with Bj below the threshold (e.g., not positive Bj). In one example, the TX UE selects the destination UE with the highest priority SL LCH with Bj >0 among all the destination UEs. If no target UE has a SL LCH with data available for transmission and has Bj >0, then the TX UE selects a target UE among all target UEs that has multiple high priority SL LCHs with data available for transmission. In another example, the TX UE selects the destination UE with the highest priority SL LCH among all the destination UEs. If more than one target UE has the highest priority SL LCH with data available for transmission, the TX UE selects the target UE from those target UEs that have the highest priority SL LCH and the Bj >0 of the highest priority SL LCH. If more than one target UE has the highest priority SL LCH with data available for transmission and with Bj >0, the UE may further compare these other metrics (e.g., delay requirements or values of Bj) with the highest priority SL LCH with data available for transmission and with Bj >0 to determine the winner of the SL LCH and then determine the selected target UE (i.e., the selected target UE is associated with the winner SL LCH). If more than one target UE has multiple highest priority SL LCHs with data available for transmission, but these highest priority SL LCHs all have Bj <0, the UE may further compare these other indicators (e.g., delay requirements or values of Bj) of the highest priority SL LCHs with data for transmission and having Bj >0 to determine the winner of the SL LCH and the selected target UE.

Although the present invention has been described in connection with certain specific embodiments for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of the various features of the described embodiments can be made without departing from the scope of the invention as set forth in the claims.

Claims

1. A method for enhancing the priority ordering of logical channels for sidelink transmission comprises the following steps:

establishing, by a transmitter user equipment, a plurality of sidelink logical channels for new radio sidelink communications, wherein the plurality of sidelink logical channels store sidelink data to be transmitted to a plurality of receiver user equipments;

maintaining an indicator value for each sidelink logical channel for each receiver user equipment, wherein each indicator indicates whether a corresponding sidelink logical channel with available sidelink data has met a minimum required bit rate to guarantee quality of service requirements for the corresponding sidelink logical channel;

selecting a target user equipment from the plurality of receiver user equipments based on both the indicator value and a sidelink logical channel priority for each sidelink logical channel for each receiver user equipment; and

and sending a medium access control protocol data unit to the selected target user equipment through a sidelink resource, wherein the sidelink resource is distributed to construct the medium access control protocol data unit by multiplexing sidelink data of a plurality of different side link logical channels from the selected target user equipment.

2. The method of claim 1, wherein during the target user equipment selection, a receiver user equipment with a sidelink logical channel that does not meet the minimum required bit rate has a higher priority than another plurality of receiver user equipments without sidelink logical channels that do not meet the minimum required bit rate, regardless of the corresponding sidelink logical channel priority.

3. The method of claim 1, wherein maintaining the indicator value for the sidelink logical channel comprises:

increasing the indicator value by the priority bit rate of the sidelink logical channel multiplied by the time elapsed since the previous increment; and

reducing the indicator value by an amount of data used for scheduling of the sidelink logical channel.

4. The method of claim 3, wherein the indicator value for the sidelink logical channel is initialized to zero when the sidelink logical channel is established, and wherein the indicator value has a maximum value equal to a memory size of the sidelink logical channel.

5. The method of claim 1, wherein a positive indicator value for a sidelink logical channel indicates that the sidelink logical channel has not met the minimum required bit rate, and wherein a negative indicator value for the sidelink logical channel indicates that the sidelink logical channel has met the minimum required bit rate.

6. The method of claim 5, wherein a user equipment having at least one sidelink logical channel with a positive indicator value has priority over a plurality of other user equipments not having a sidelink logical channel with a positive indicator value.

7. The method according to claim 5, wherein if a plurality of user equipments have at least one sidelink logical channel with a positive indicator value, the user equipment having the sidelink logical channel with the positive indicator value and having the highest logical channel priority is selected as the target user equipment.

8. The method according to claim 5, wherein if there is no user equipment having at least one sidelink logical channel with a positive indicator value, selecting the user equipment having the sidelink logical channel with the highest logical channel priority as the target user equipment.

9. The method of claim 1, wherein the sidelink resources are allocated to the plurality of different sidelink logical channels of the selected target user equipment in descending order of corresponding sidelink logical channel priorities.

10. The method of claim 1, wherein a sidelink logical channel is associated with a sidelink radio bearer mapped to one or more quality of service flows defining the quality of service requirements of the sidelink logical channel.

11. A logical channel prioritized enhanced transmitter user equipment for sidelink transmissions, comprising:

a processor configured to establish a plurality of sidelink logical channels for new radio sidelink communications, wherein the plurality of sidelink logical channels store sidelink data to be transmitted to a plurality of receiver user equipments;

control and configuration circuitry to maintain an indicator for each sidelink logical channel for each receiver user equipment, wherein each indicator indicates whether a corresponding sidelink logical channel with available sidelink data has met a minimum required bit rate to guarantee quality of service requirements for the corresponding sidelink logical channel;

a logical channel prioritization processing circuit to select a target user equipment from the plurality of receiver user equipments based on both the indicator value and a sidelink logical channel priority for each sidelink logical channel for each receiver user equipment; and

a transceiver, configured to send a medium access control protocol data unit to the selected target ue through a sidelink resource, wherein the sidelink resource is allocated to construct the medium access control protocol data unit by multiplexing sidelink data of a plurality of different sidelink logical channels from the selected target ue.

12. The UE of claim 11, wherein during the target UE selection, a receiver UE with a sidelink logical channel that does not meet the minimum required bit rate has a higher priority than a plurality of other receiver UEs without sidelink logical channels that do not meet the minimum required bit rate, regardless of the corresponding sidelink logical channel priority.

13. The UE of claim 11, wherein the UE maintains the indicator value for the sidelink logical channel by increasing the indicator value by a priority bit rate of the sidelink logical channel multiplied by an elapsed time since a previous increment and by decreasing the indicator value by a scheduled data amount for the sidelink logical channel.

14. The UE of claim 13, wherein the indicator value of the sidelink logical channel is initialized to zero when the sidelink logical channel is established, and wherein the indicator value has a maximum value equal to a memory size of the sidelink logical channel.

15. The user equipment of claim 11, wherein a positive indicator value for a sidelink logical channel indicates that the sidelink logical channel does not meet the minimum required bit rate, and wherein a negative indicator value for the sidelink logical channel indicates that the sidelink logical channel has met the minimum required bit rate.

16. The UE of claim 15, wherein a UE having at least one sidelink logical channel with a positive indicator value has priority over a plurality of other UEs not having a sidelink logical channel with a positive indicator value.

17. The UE of claim 15, wherein if a plurality of UEs have at least one sidelink logical channel with a positive indicator value, the UE having the sidelink logical channel with the positive indicator value and having the highest logical channel priority is selected as the target UE.

18. The UE of claim 15, wherein if there is no UE having at least one sidelink logical channel with a positive indicator value, the UE having the sidelink logical channel with the highest logical channel priority is selected as the target UE.

19. The UE of claim 11, wherein the sidelink resources are allocated to the plurality of different sidelink logical channels of the selected target UE in descending order of corresponding sidelink logical channel priorities.

20. The user equipment of claim 11, wherein a sidelink logical channel is associated with a sidelink radio bearer mapped to one or more quality of service flows defining the quality of service requirements of the sidelink logical channel.

21. A non-transitory computer readable storage medium comprising instructions and data which, when executed by a processor of an enhanced user equipment for logical channel prioritization for sidelink transmissions, cause the user equipment to:

establishing a plurality of sidelink logical channels for new radio sidelink communications, wherein the plurality of sidelink logical channels store sidelink data to be transmitted to a plurality of receiver user equipments;