WO2022077443A1

WO2022077443A1 - Methods and apparatuses for multi-trp transmission

Info

Publication number: WO2022077443A1
Application number: PCT/CN2020/121530
Authority: WO
Inventors: Lingling Xiao; Bingchao LIU; Chenxi Zhu; Wei Ling; Yi Zhang
Original assignee: Lenovo (Beijing) Limited
Priority date: 2020-10-16
Filing date: 2020-10-16
Publication date: 2022-04-21

Abstract

Embodiments of the present disclosure relate to a method and apparatus for multiple transmit-receive points (multi-TRP) transmission. According to an embodiment of the present disclosure, a method can include: receiving downlink control information (DCI) for activating a semi-persistent scheduling (SPS) configuration for a physical downlink shared channel (PDSCH) transmission, wherein the DCI indicates at least one antenna port, and wherein the DCI include a transmission configuration indicator (TCI) codepoint indicating a first set of TCI states; receiving an activation command, wherein the activation command indicates that the TCI codepoint corresponds to a second set of TCI states; and determining a third set of TCI states for receiving the PDSCH transmission based on the activation command. Embodiments of the present disclosure can solve the technical problem caused by parameter changes in SPS transmission.

Description

METHODS AND APPARATUSES FOR MULTI-TRP TRANSMISSION

TECHNICAL FIELD

Embodiments of the present application generally relate to wireless communication technology, and in particular to a method and an apparatus for multiple transmit-receive points (multi-TRP) transmission.

BACKGROUND

Multi-TRP transmission has been introduced into New Radio (NR) . During multi-TRPs transmission, two TRPs (or panels) may be used to transmit data to a user equipment (UE) to improve reliability and robustness. For example, physical downlink shared channel (PDSCH) transmission with multi-TRP (or panel) to improve reliability and robustness including ultra reliable and low latency communication (URLLC) requirements are specified in Rel-16. In Rel-16, the PDSCH transmission may be dynamically scheduled by downlink control information (DCI) or may be transmitted based on a semi-persistent scheduling (SPS) configuration.

For the SPS configuration, after DCI activates the SPS configuration for the PDSCH transmission, the PDSCH transmission will be transmitted according to radio resource control (RRC) parameters and parameters indicated by the DCI until the SPS configuration is deactivated by another DCI. During the transmission of the PDSCH, some parameters may be changed by the network, and thus the changed parameters may mismatch with the information indicated in the DCI.

Given the above, it is desirable to provide improved technology for multi-TRP transmission, so as to solve the technical problem caused by parameter changes in SPS transmission.

SUMMARY OF THE APPLICATION

Some embodiments of the present application provide a technical solution for multi-TRP transmission.

According to some embodiments of the present application, a method may include: receiving DCI for activating a SPS configuration for a PDSCH transmission, wherein the DCI indicates at least one antenna port, and wherein the DCI include a transmission configuration indicator (TCI) codepoint indicating a first set of TCI states; receiving an activation command, wherein the activation command indicates that the TCI codepoint corresponds to a second set of TCI states; and determining a third set of TCI states for receiving the PDSCH transmission based on the activation command.

In an embodiment of the present application, the at least one antenna port is antenna ports 0, 2, and 3, and the first set of TCI states includes two TCI states.

In another embodiment of the present application, the second set of TCI states includes one TCI state.

In another embodiment of the present application, determining the third set of TCI states may further include: determining the third set of TCI states to include two TCI states corresponding to a lowest TCI codepoint of all TCI codepoints corresponding to two TCI states indicated by the activation command.

In another embodiment of the present application, determining the third set of TCI states may further include: determining the third set of TCI states to include the one TCI state corresponding to the TCI codepoint indicated by the activation command.

In another embodiment of the present application, the second set of TCI states includes two TCI states. The method may further include: determining the third set of TCI states to include two TCI states corresponding to the TCI codepoint indicated by the activation command.

In another embodiment of the present application, the at least one antenna port is included in one code division multiplexing (CDM) group, the first set of TCI states includes one TCI state, a time domain resource assignment (TDRA) field in the DCI indicates an entry in PDSCH time domain allocation list not containing an ultra-reliable and low latency communication (URLLC) repetition number, and a higher layer parameter does not indicate a URLLC repetition scheme.

In another embodiment of the present application, the second set of TCI states includes two TCI states.

In another embodiment of the present application, determining the third set of TCI states may further include: determining the third set of TCI states to include a first TCI state corresponding to a lowest TCI codepoint of all TCI codepoints indicated by the activation indication.

In another embodiment of the present application, determining the third set of TCI states may further include: determining the third set of TCI states to include one TCI state corresponding to a lowest TCI codepoint of all TCI codepoints corresponding to one TCI state indicated by the activation command.

In another embodiment of the present application, determining the third set of TCI states may further include: determining the third set of TCI states to include a first TCI state of the two TCI states corresponding to the TCI codepoint indicated by the activation command.

In another embodiment of the present application, the second set of TCI states includes one TCI state. The method may further include: determining the third set of TCI states to include one TCI state corresponding to the TCI codepoint indicated by the activation command.

In another embodiment of the present application, the at least one antenna port is included in one CDM group, the first set of TCI states includes two TCI states, and a higher layer parameter indicates a frequency division multiplexing (FDM) repetition scheme.

In another embodiment of the present application, determining the third set of TCI states may include: determining the third set of TCI states to include two TCI states corresponding to a lowest TCI codepoint of all TCI codepoints corresponding to two TCI states indicated by the activation command.

According to some other embodiments of the present application, a method may include: transmitting DCI for activating a SPS configuration for a PDSCH transmission, wherein the DCI indicates at least one antenna port, and wherein the DCI include a TCI codepoint indicating a first set of TCI states; transmitting an activation command, wherein the activation command indicates that the TCI codepoint corresponds to a second set of TCI states; and determining a third set of TCI states for transmitting the PDSCH transmission based on the activation command.

Some embodiments of the present application also provide an apparatus, include: at least one non-transitory computer-readable medium having computer executable instructions stored therein; at least one receiving circuitry; at least one transmitting circuitry; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuitry and the at least one transmitting circuitry. The computer executable instructions are programmed to implement any method as stated above with the at least one receiving circuitry, the at least one transmitting circuitry and the at least one processor.

Embodiments of the present application provide a technical solution for multi-TRP transmission, so as to solve the technical problem caused by parameter changes in SPS transmission, thereby realizing reliability and robustness in the multi-TRP transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of the application can be obtained, a description of the application is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only example embodiments of the application and are not therefore to be considered limiting of its scope.

FIG. 1 is a schematic diagram illustrating an exemplary wireless communication system according to some embodiments of the present application;

FIG. 2 illustrates a method for multi-TRP transmission according to some embodiments of the present application;

FIG. 3 illustrates an example of TCI state updating by an activation command according to some embodiments of the present application;

FIG. 4 illustrates another example of TCI state updating by an activation command according to some other embodiments of the present application;

FIG. 5 illustrates another example of TCI state updating by an activation command according to some other embodiments of the present application; and

FIG. 6 illustrates a simplified block diagram of an apparatus for multi-TRP transmission according to some embodiments of the present application.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of the preferred embodiments of the present application and is not intended to represent the only form in which the present application may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present application.

Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architecture and new service scenarios, such as the 3rd generation partnership project (3GPP) 5G (NR) , 3GPP long-term evolution (LTE) Release 8, and so on. It is contemplated that along with the developments of network architectures and new service scenarios, all embodiments in the present application are also applicable to similar technical problems; and moreover, the terminologies recited in the present application may change, which should not affect the principle of the present application.

A wireless communication system generally includes one or more base stations (BSs) and one or more UEs. Furthermore, a BS may be configured with one TRP (or panel) or more TRPs (or panels) . A TRP can act like a small BS. The TRPs can communicate with each other by a backhaul link. Such backhaul link may be an ideal backhaul link or a non-ideal backhaul link. Latency of the ideal backhaul link may be deemed as zero, and latency of the non-ideal backhaul link may be tens of milliseconds and much larger, e.g. on the order of tens of milliseconds, than that of the ideal backhaul link.

In a wireless communication system, one single TRP can be used to serve one or more UEs under control of a BS. In different scenario, TRP may be called in different terms. Persons skilled in the art should understand that as the 3rd Generation Partnership Project (3GPP) and the communication technology develop, the terminologies recited in the specification may change, which should not affect the scope of the present application. It should be understood that the TRP (s) (or panel (s) ) configured for the BS may be transparent to a UE.

FIG. 1 is a schematic diagram illustrating an exemplary wireless communication system 100 according to some embodiments of the present application.

Referring to FIG. 1, a wireless communication system 100 can include a base station (BS) 101, TRPs 103 (e.g., TRP 103a and TRP 103b) , and UEs 105 (e.g., UE 105a, UE 105b, and UE 105c) . Although only one base station 101, two TRPs 103 and three UEs 105 are shown for simplicity, it should be noted that the wireless communication system 100 may include more or less communication device (s) or apparatus in accordance with some other embodiments of the present application.

In some embodiments of the present application, a BS 101 may be referred to as an access point, an access terminal, a base, a base unit, a macro cell, a Node-B, an evolved Node B (eNB) , a gNB, an ng-eNB, a Home Node-B, a relay node, or a device, or described using other terminology used in the art. The UEs 105 (for example, the UE 105a, the UE 105b, and the UE 105c) may include, for example, but is not limited to, a computing device, a wearable device, a mobile device, an IoT device, a vehicle, etc.

The TRPs 103, for example, the TRP 103a and the TRP 103b can communicate with the base station 101 via, for example, a backhaul link. Each of TRPs 103 can serve some or all of UEs 105. As shown in FIG. 1, the TRP 103a can serve some mobile stations (which include the UE 105a, the UE 105b, and the UE 105c) within a serving area or region (e.g., a cell or a cell sector) . The TRP 103b can serve some mobile stations (which include the UE 105a, the UE 105b, and the UE 105c) within a serving area or region (e.g., a cell or a cell sector) . The TRP 103a and the TRP 103b can communicate to each other via, for example, a backhaul link.

The multi-TRP transmission may refer to at least two TRPs (or panels) to transmit data to a UE. As shown in FIG. 1, for the UE 105 (e.g., UE 105a, UE 105b, or UE 105c) , two TRPs (e.g., TRP 103a and TRP 103b) may be used to transmit data to it, which is an example of the multi-TRP transmission. In Rel-16, PDSCH transmission with multi-TRP is specified to improve reliability and robustness. According to some embodiments of the present application, the PDSCH transmission with multi-TRP may be dynamically scheduled by DCI. According to some other embodiments of the present application, the PDSCH transmission with multi-TRP may be transmitted based on a SPS configuration.

For the SPS configuration, after DCI activating the SPS configuration for the PDSCH transmission, the PDSCH transmission will be transmitted according to higher layer parameters (e.g., RRC parameters) configured by the BS and parameters indicated by the DCI until the SPS configuration is deactivated by another DCI. During the transmission of the SPS PDSCH, the higher layer parameters configured by the BS and the parameters indicated by the DCI are deemed to be unchanged by the UE.

However, in some cases, the BS may update some parameters (e.g., TCI state) in a bandwidth part (BWP) during the transmission of SPS PDSCH, these updated parameters may mismatch with the RRC parameters configured by the BS or parameters indicated by the DCI (for example, antenna ports indicated by the DCI) , and thus the PDSCH transmission cannot be transmitted or received normally. For example, antenna port entry {0, 2, 3} is added in Rel-16 to support multi-TRP transmission and the entry can only be used when a TCI codepoint included in the DCI indicates two TCI states. In some cases, the BS may update the TCI state such that the TCI codepoint may only indicate one TCI state. In these cases, PDSCH transmission based on multi-TRP cannot be performed, which is a technical problem to be solved by some embodiments of the present application. This technical problem is just an example, other technical problems may also be caused by TCI state changes during SPS transmission.

Given the above, embodiments of the present application aim to provide solutions for multi-TRP transmission. Accordingly, embodiments of the present application at least can solve the technical problems caused by TCI state changes during SPS transmission. More details on embodiments of the present application will be illustrated in the following text in combination with the appended drawings.

FIG. 2 illustrates a method for multi-TRP transmission according to some embodiments of the present application. Although the method is illustrated in a system level by a UE and a BS (e.g., UE 105 and BS 101 as illustrated and shown in FIG. 1) , persons skilled in the art can understand that the method implemented in the UE and that implemented in the BS can be separately implemented and incorporated by other apparatus with the like functions.

In the exemplary method in FIG. 2, before performing operation 201 in FIG. 2, the BS 101 may transmit (i.e., configure) higher layer (i.e., a layer higher than the physical layer) parameters (e.g., RRC parameters) to the UE 105. The higher layer parameters may be associated with a SPS configuration for a PDSCH transmission. For example, the higher layer parameters may include at least one TCI state configuration. Each TCI state configuration may include a quasi co-location (QCL) configuration and a reference signal (RS) configuration. For example, the higher layer parameters may also indicate a URLLC repetition scheme, e.g. by a higher layer parameter RepSchemeEnabler as specified in 3GPP standard documents.

The configured at least one TCI state is in the deactivated state and needs to be activated through an activation command. That is, after transmitting the higher layer parameters, the BS 101 may transmit a first activation command to the UE 105. The first activation command may be a higher layer command (e.g., a medium access control (MAC) control element (CE) command for TCI states activation/deactivation for UE-specific PDSCH as specified in 3GPP standard documents) . The first activation command may at most activate eight sets of TCI states. Each set of TCI states may correspond to a TCI codepoint in a DCI and each set may include one or two TCI states.

After that, in operation 201, the BS 101 as shown in FIG. 1 may transmit DCI for activating the SPS configuration for a PDSCH transmission. The SPS configuration for the PDSCH transmission may include the higher layer parameters configured by the BS 101 before transmitting the DCI and parameters indicated by the DCI. For example, the DCI may indicate at least one antenna port and include a TCI codepoint indicating a first set of TCI states which is one of the at most eight sets of TCI states activated by the activation command. The TCI codepoint may be included in a TCI field of the DCI. The TCI field may include three bits. That is, the TCI codepoint may have one of the values "000, " "001, " "010, " "011, " "100, " "101, " "110, "and "111. " The set of TCI states corresponding to a TCI codepoint may be determined based on an order of the eight sets of TCI states activated by the first activation command transmitted before the DCI. For example, the TCI codepoint value "000" may indicate a first set of TCI states activated by the first activation command, the TCI codepoint value "001" may indicate a second set of TCI states activated by the first activation command, ……, and so on.

In an embodiment of the present application, each TCI of the first set of TCI state may be associated a TRP in the multi-TRP transmission. Each TCI state may include a QCL configuration and a RS configuration.

Consequently, in operation 202, the UE 105 (e.g., the UE 105a, the UE 105b, or the UE 105c) may receive the DCI for activating the SPS configuration from the BS 101.

After activating the SPS configuration for the PDSCH transmission by the DCI, in some cases, the BS 101 may transmit the PDSCH transmission with at least one TRP (e.g., TRP 103a and/or TRP 103b) according to the SPS configuration, and thus the UE 105 may receive the PDSCH transmission according to the SPS configuration from at least one TRP (e.g., TRP 103a and/or TRP 103b) . During the PDSCH transmission, the parameters included in the SPS configuration may be deemed to be unchanged by the BS 101 and UE 105.

However, during the PDSCH transmission, the BS may change the TCI states in some cases. For example, after transmitting the DCI activating the SPS configuration, the BS 101 may transmit another activation command (i.e., a second activation command) to the UE 105 in operation 203. The second activation command may also be a higher layer command (e.g., a MAC CE command) . In some embodiments of the present application, the second activation command may also be referred to as a MAC CE command for TCI state activation/deactivation of PDSCH transmission. The second activation command may be used for updating the TCI state (s) of PDSCH transmission in the BWP.

The second activation command may indicate that the TCI codepoint corresponds to a second set of TCI states (in other words, the second activation command may indicate the TCI codepoint is associated with a second set of TCI states or the second activation command may map the TCI codepoint to a second set of TCI states) . The second set of TCI states may include at least one TCI state. The second set of TCI states may be different from the first set of TCI states. In some embodiments, in addition to the TCI codepoint, the second activation command may also indicate that at least one other TCI codepoint corresponds to at least one other set of TCI states.

Consequently, in operation 204, the UE 105 may receive the second activation command from the BS 101.

Then, in operation 205, the BS 101 may determine a third set of TCI states for transmitting the PDSCH transmission based on the second activation command. In operation 206, the UE 105 may determine a third set of TCI states for receiving the PDSCH transmission based on the second activation command. The BS 101 and the UE 105 may use the same rule to determine the third set of TCI states for the PDSCH transmission, which will be illustrated as follows.

According to some embodiments of the present application, the at least one antenna port indicated in the DCI may be antenna ports 0, 2, and 3 and the first set of TCI states indicated by the TCI codepoint may include two TCI states. In some embodiments of the present application, the antenna ports may also be referred to as demodulation reference signal (DMRS) ports. Antenna ports 0, 2, and 3 are added in Rel-16 to support multi-TRP transmission and the entry could only be used when the TCI codepoint included in a DCI indicates two TCI states.

In these embodiments, FIG. 3 illustrates an example of TCI state updating by an activation command (for example, the second activation command) .

As shown in FIG. 3, the DCI for activating the SPS configuration may indicate antenna ports 0, 2, and 3, and the TCI codepoint included in the DCI may indicate two TCI states.

After transmitting the DCI, the BS 101 may use non-coherent joint transmission (NCJT) scheme to transmit the SPS transmission (e.g., PDSCH transmission) , and thus the UE 105 may assume that antenna port 0 of the SPS PDSCH transmission is QCLed with RS (s) included in the first TCI state of the two TCI states and assume that antenna port 2 and antenna port 3 of the SPS PDSCH transmission is QCLed with RS (s) included in the second TCI state of the two TCI states.

Referring to FIG. 3, during the PDSCH transmission, the BS 101 may transmit an activation command (e.g., the second activation command) to the UE 105. The second activation command may indicate that the TCI codepoint corresponds to a second set of TCI states. In the example of FIG. 3, the second set of TCI states may only include one TCI state (i.e., the TCI codepoint indicating one TCI state) . Then, how to determine the third set of TCI states for the following PDSCH transmission needs to be specified.

In an embodiment of the present application, the UE 105 may assume the PDSCH transmission will continue to be transmitted by antenna ports {0, 2, 3} using two TCI states. In this embodiment, the BS 101 and the UE 105 may determine the third set of TCI states to include two TCI states corresponding to a lowest TCI codepoint of all TCI codepoints corresponding to two TCI states indicated by the second activation command.

For example, assuming that the antenna ports indicted by the DCI are {0, 2, 3} and the TCI codepoint included in the DCI is "011. " And assuming that the forth set of TCI state among the at most eight sets of TCI states activated by the first activation command indicated are TCI state #0 and TCI state #1. Based on the first activation command transmitted before the DCI, the BS 101 and the UE 105 may determine that the TCI codepoint "011" may indicate TCI state #0 and TCI state #1.

The second activation command may update TCI states for at least one TCI codepoint including the TCI codepoint. That is, the second activation command may indicate that at least one TCI codepoint corresponds to at least one set of TCI states. For example, table 1 shown below illustrates an exemplary correspondence between TCI codepoints and TCI states indicated by the second activation command.

Referring to table 1, the activation command indicates the correspondence between eight TCI codepoints and eight sets of TCI states. In table 1, the activation command indicates that the TCI codepoint "011" corresponds to TCI state #38.

In table 1, all the TCI codepoints corresponding to two TCI states may include TCI codepoints "001, " "010, " and "101, " and thus the lowest TCI codepoint corresponding to two TCI states is TCI codepoint "001. " Therefore, the BS 101 and the UE 105 may determine the third set of TCI states to include two TCI states (i.e., TCI state #12 and TCI state #20) corresponding to TCI codepoint "001. "

Table 1

TCI codepoint	TCI state (s)
000	TCI state #10

001	TCI state#12 and TCI state#20
010	TCI state #20 and TCI state #38
011	TCI state #38
100	TCI state #52
101	TCI state #52 and TCI state #55
110	TCI state #78
111	TCI state #80

After determining the third set of TCI states, the BS 101 and the UE 105 may assume that antenna port 0 of the SPS PDSCH transmission is QCLed with RS (s) with respect to QCL parameter (s) associated with TCI state #12 and assume that antenna port 2 an antenna port 3 of the SPS PDSCH transmission are QCLed with RS (s) with respect to QCL parameter (s) associated with TCI state #20. The BS 101 may transmit (the UE 105 may receive) the PDSCH transmission of antenna port 0 from a TRP (e.g., TRP 103a) according to the parameters (e.g., QCL parameters and RS parameters) included in the TCI state #12 and transmit the PDSCH transmission of antenna port 2 and antenna port 3 from another TRP (e.g., TRP 103b) according to the parameters included in the TCI state #20.

In another embodiment of the present application, the BS 101 and the UE 105 may determine the third set of TCI states to include the one TCI state corresponding to the TCI codepoint indicated by the activation command. In this embodiment, antenna ports {0, 2, 3} is extended to be used for single TCI transmission (i.e. single TRP transmission) , and the UE will switch from multi-TRP transmission to single TRP transmission.

For example, still referring to table 1, the activation command indicates that the TCI codepoint "011" corresponds to TCI state #38. Therefore, the BS 101 and the UE 105 may determine the third set of TCI states to include TCI state #38 corresponding to TCI codepoint "011. "

After determining the third set of TCI states, the BS 101 and the UE 105 may assume that antenna ports 0, 2, 3 of the SPS PDSCH transmission are QCLed with RS (s) with respect to QCL parameter (s) associated with TCI state #38. The BS 101 may transmit (the UE 105 may receive) the PDSCH transmission from one TRP (e.g., TRP 103a or TRP 103b) according to the parameters (e.g., QCL parameters and RS parameters) included in the TCI state #38.

In yet another embodiment of the present application, since the antenna ports {0, 2, 3} can only be used with two TCI states, updating the two TCI states to one TCI state may make the updated TCI unusable, which is not expected by the UE 105. Accordingly, in this embodiment, the TCI codepoint always correspond to two TCI states by the second activation command. That is, the second activation command may indicate the TCI codepoint corresponds to two TCI states (i.e., the second set of TCI states includes two TCI states) . Then, the BS 101 and the UE 105 may determine the third set of TCI states for the PDSCH transmission to be the same as the second set of TCI states. That is, the BS 101 and the UE 105 may determine the third set of TCI states to include the two TCI states corresponding to the TCI codepoint indicated by the second activation command.

For example, assuming that the second activation command indicates that the TCI codepoints "011" corresponds to TCI state #10 and TCI state #100, then the BS 101 and the UE 105 may determine the third set of TCI states to be TCI state #10 and TCI state #100. After determining the third set of TCI states, the BS 101 and the UE 105 may assume that antenna port 0 of the SPS PDSCH transmission is QCLed with RS (s) with respect to QCL parameter (s) associated with TCI state #10 and assume that antenna port 2 an antenna port 3 of the SPS PDSCH transmission are QCLed with RS (s) with respect to QCL parameter (s) associated with TCI state #100.

According to some other embodiments of the present application, in the case that the at least one antenna port is included in one CDM group, the first set of TCI states includes one TCI state, a TDRA field in the DCI indicates an entry in PDSCH time domain allocation list (e.g., pdsch-TimeDomainAllocationList as specified in 3GPP standard documents) not containing an URLLC repetition number (e.g., RepNumR16 as specified in 3GPP stardard documents) , and a higher layer parameter (e.g., RepSchemeEnabler as specified in 3GPP standard documents) transmitted from the BS does not indicate (or configure) a URLLC repetition scheme (FDMSchemeA, FDMSchemeB or TDMSchemeA as specified in 3GPP standard documents) , the BS 101 may use Rel-15 scheme to transmit the SPS PDSCH transmission from a single TRP.

In these embodiments, FIG. 4 illustrates another example of TCI state updating by an activation command (for example, the second activation command) .

As shown in FIG. 4, the at least one antenna ports indicated by the DCI is included in one CDM group, the TCI codepoint included in the DCI may indicate one TCI state, the TDRA field in the DCI indicating an entry in pdsch-TimeDomainAllocationList not containing RepNumR16 and a UE is not configured as 'TDMSchemeA' by a higher layer parameter RepSchemeEnabler, the BS 101 may use Rel-15 scheme to transmit the SPS transmission (e.g., PDSCH transmission) from a single TRP. The BS 101 and the UE 105 may assume antenna ports of the SPS PDSCH transmission are QCLed with RS (s) with respect to QCL parameter (s) associated with the TCI state indicated by the TCI codepoint.

Referring to FIG. 4, during the PDSCH transmission, the BS 101 may transmit an activation command (e.g., the second activation command) to the UE 105. The second activation command may indicate that the TCI codepoint corresponds to a second set of TCI states. In the example of FIG. 4, the second set of TCI states may include two TCI state (i.e., the TCI codepoint indicating two TCI states) . Since PDSCH transmission by Rel-15 scheme (i.e. from single TRP) require only one TCI state then how to determine the third set of TCI states for the following PDSCH transmission needs to be specified.

In an embodiment of the present application, the UE 105 may assume the PDSCH transmission will continue to be transmitted using one TCI state. In this embodiment, the BS 101 and UE 105 may determine the third set of TCI states to include a first TCI state corresponding to a lowest TCI codepoint of all TCI codepoints indicated by the activation indication.

For example, assuming that the antenna ports are {0, 1} included in CDM group #0 and the TCI codepoint included in the DCI is "001. " And assuming that the second set of TCI state among the at most eight sets of TCI states activated by the first activation command indicated are TCI state #100. Based on the first activation command transmitted before the DCI, the UE 105 may determine that the TCI codepoint "001" may indicate TCI state #100.

The second activation command may update TCI states for at least one TCI codepoint including the TCI codepoint. That is, the second activation command may indicate that at least one TCI codepoint corresponds to at least one set of TCI states. For example, table 2 shown below illustrates another exemplary correspondence between TCI codepoints and TCI states indicated by the second activation command.

Referring to table 2, the activation command indicates the correspondence between eight TCI codepoints and eight sets of TCI states. In table 2, the activation command indicates that the TCI codepoint "001" corresponds to TCI state #20 and TCI state #30.

In table 2, the lowest TCI codepoint of all the TCI codepoints indicated by the activation command is TCI codepoint "000. " A first TCI state corresponding to the TCI code point "000" is TCI state #10. Therefore, the BS 101 and the UE 105 may determine the third set of TCI states to include TCI state #10 corresponding to the TCI codepoint "000. "

Table 2

TCI codepoint	TCI state (s)
000	TCI state #10 and TCI state #15
001	TCI state #20 and TCI state #30
010	TCI state #38
011	TCI state #55
100	TCI state #59 and TCI state #60
101	TCI state #60
110	TCI state #78
111	TCI state #80

After determining the third set of TCI states, the BS 101 and the UE 105 may assume that antenna ports 0 and 1 of the SPS PDSCH transmission is QCLed with RS (s) with respect to QCL parameter (s) associated with TCI state #10. The BS 101 may transmit (the UE 105 may receive) the PDSCH transmission of antenna ports 0 and 1 from a TRP (e.g., TRP 103a) according to the parameters (e.g., QCL-parameters and RS parameters) included in the TCI state #10.

In another embodiment of the present application, the UE 105 may determine the third set of TCI states to include one TCI state corresponding to a lowest TCI codepoint of all TCI codepoints corresponding to one TCI state indicated by the activation command.

For example, still referring to table 2, all the TCI codepoints corresponding to one TCI state in table 2 may include TCI codepoints "010, " "011, " "101, " "110, " and "111, " and thus the lowest TCI codepoint corresponding to one TCI state is TCI codepoint "010. " Therefore, the BS 101 and the UE 105 may determine the third set of TCI states to include one TCI state (i.e., TCI state #38) corresponding to TCI codepoint "010. "

After determining the third set of TCI states, the BS 101 and the UE 105 may assume that antenna ports 0 and 1 of the SPS PDSCH transmission is QCLed with RS (s) with respect to QCL parameter (s) associated with TCI state #38. The BS 101 may transmit (the UE 105 may receive) the PDSCH transmission of antenna ports 0 and 1 from a TRP (e.g., TRP 103a) according to the parameters (e.g., QCL-parameters and RS parameters) included in the TCI state #38.

In yet another embodiment of the present application, the UE 105 may determine the third set of TCI states to include a first TCI state of the two TCI states corresponding to the TCI codepoint indicated by the activation command.

For example, still referring to table 2, the activation command indicates that the TCI codepoint "001" corresponds to TCI state #20 and TCI state #30. That is, the first TCI state corresponding to the TCI codepoint "001" is TCI state #20. Therefore, the BS 101 and the UE 105 may determine the third set of TCI states to include a first TCI state (i.e., TCI state #20) corresponding to TCI codepoint "001. "

After determining the third set of TCI states, the BS 101 and the UE 105 may assume that antenna ports 0 and 1 of the SPS PDSCH transmission is QCLed with RS (s) with respect to QCL parameter (s) associated with TCI state #20. The BS 101 may transmit (the UE 105 may receive) the PDSCH transmission of antenna ports 0 and 1 from a TRP (e.g., TRP 103a) according to the parameters (e.g., QCL-parameters and RS parameters) included in the TCI state #20.

In yet another embodiment of the present application, since the Rel-15 SPS PDSCH transmission scheme can only be performed with one TCI state, updating the one TCI state to two TCI states may make the updated TCI unusable, which is not expected by the UE 105. In this embodiment, the second activation command may indicate the TCI codepoint corresponds to one TCI state (i.e., the second set of TCI states includes one TCI state) . Then, the BS 101 and the UE 105 may determine the third set of TCI states for the PDSCH transmission to be the same as the second set of TCI states. That is, the BS 101 and the UE 105 may determine the third set of TCI states to include the one TCI state corresponding to the TCI codepoint indicated by the second activation command.

For example, assuming that the second activation command indicates that the TCI codepoints "001" corresponds to TCI state #30, then the BS 101 and the UE 105 may determine the third set of TCI states to include TCI state #30. After determining the third set of TCI states, the BS 101 and the UE 105 may assume that antenna ports 0 and 1 of the SPS PDSCH transmission is QCLed with RS (s) with respect to QCL parameter (s) associated with TCI state #30. The BS 101 may transmit (the UE 105 may receive) the PDSCH transmission of antenna ports 0 and 1 from a TRP (e.g., TRP 103a) according to the parameters (e.g., QCL-parameters and RS parameters) included in the TCI state #30.

According to some other embodiments of the present application, in the case that the at least one antenna port is included in one CDM group, the first set of TCI states includes two TCI states, and a higher layer parameter (e.g., RepSchemeEnabler as specified in 3GPP standard documents) transmitted from the BS indicates (or configure) a frequency division multiplexing (FDM) repetition scheme (FDMSchemeA or FDMSchemeB as specified in 3GPP stardard documents) , the BS 101 may use scheme 2a or scheme 2b as specified in 3GPP standard documents to transmit the SPS PDSCH transmission from two TRPs.

For example, in the case that FDMSchemeA is configured for the UE, BS 101 may transmit the SPS PDSCH transmission using the scheme 2a, wherein the UE may receive a single PDSCH transmission occasion with each TCI state associated to a non-overlapping frequency domain resource allocation. In the case that FDMSchemeB is configured for the UE, BS 101 may transmit the SPS PDSCH transmission using the scheme 2b, wherein the UE may receive two PDSCH transmission occasions with each TCI state associated to a PDSCH transmission occasion which has non-overlapping frequency domain resource allocation with respect to the other PDSCH transmission occasion.

In these embodiments, FIG. 5 illustrates yet another example of TCI state updating by an activation command (for example, the second activation command) .

As shown in FIG. 5, the at least one antenna ports indicated by the DCI is included in one CDM group, the TCI codepoint included in the DCI may indicate two TCI states, and a UE is configured as 'FDMSchemeA' or 'FDMSchemeB' by higher layer parameter RepSchemeEnabler, the BS 101 may use scheme 2a or 2b to transmit the SPS transmission (e.g., PDSCH transmission) from two TRPs.

Referring to FIG. 5, during the PDSCH transmission, the BS 101 may transmit an activation command (e.g., the second activation command) to the UE 105. The second activation command may indicate that the TCI codepoint corresponds to a second set of TCI states. In the example of FIG. 5, the second set of TCI states may only include one TCI state (i.e., the TCI codepoint indicating one TCI state) . Since scheme 2a/2b requires two TCI states for the PDSCH transmissionthen, how to determine the third set of TCI states for the following PDSCH transmission needs to be specified.

In an embodiment of the present application, the UE 105 may assume the PDSCH transmission will continue to be transmitted by using two TCI states. In this embodiment, the BS 101 and the UE 105 may determine the third set of TCI states to include two TCI states corresponding to a lowest TCI codepoint of all TCI codepoints corresponding to two TCI states indicated by the second activation command.

For example, assuming that the higher layer parameter RepSchemeEnabler is set to be 'FDMSchemeA' , the antenna ports indicted by the DCI are {2, 3} included in one CDM group and the TCI codepoint included in the DCI is "111. " And assuming that the eighth set of TCI state among the at most eight sets of TCI states activated by the first activation command indicated are TCI state #10 and TCI state #100 Based on the first activation command transmitted before the DCI, the BS 101 and the UE 105 may determine that the TCI codepoint "111" may indicate TCI state #10 and TCI state #100.

The second activation command may update TCI states for at least one TCI codepoint including the TCI codepoint. That is, the second activation command may indicate that at least one TCI codepoint corresponds to at least one set of TCI states. For example, Referring to table 1 shown above, the activation command indicates the correspondence between eight TCI codepoints and eight sets of TCI states. In table 1, the activation command indicates that the TCI codepoint "111" corresponds to TCI state #80.

After determining the third set of TCI states, if the precoding granularity is two, the BS 101 and the UE 105 may assume even physical resource bock groups (PRGs) within the allocated frequency domain resources for the PDSCH transmission are assigned to TCI state #12 and odd PRGs within the allocated frequency domain resources for the PDSCH transmission are assigned to TCI state #20. The BS 101 may transmit (the UE 105 may receive) the PDSCH transmission on even PRGs of antenna port 2 and antenna port 3 from a TRP (e.g., TRP 103a) according to the parameters (e.g., QCL parameters and RS parameters) included in the TCI state #12 and transmit the PDSCH transmission on odd PRGs of antenna port 2 and antenna port 3 from another TRP (e.g., TRP 103b) according to the parameters included in the TCI state #20.

In another embodiment of the present application, the scheme 2a or 2b may only be performed with two TCI states, updating the two TCI states to one TCI state may make the updated TCI unusable, which is not expected by the UE 105. Accordingly, in this embodiment, the TCI codepoint always correspond to two TCI states. That is, the second activation command may indicate the TCI codepoint corresponds to two TCI states (i.e., the second set of TCI states includes two TCI states) . Then, the BS 101 and the UE 105 may determine the third set of TCI states for transmitting and receiving the PDSCH transmission to be the same as the second set of TCI states. That is, the BS 101 and the UE 105 may determine the third set of TCI states to include the two TCI states corresponding to the TCI codepoint indicated by the second activation command.

After determining the third set of TCI states, the UE may apply the two TCI states for receiving the SPS PDSCH transmission with the same mapping rule of TCI states and the non-overlapping frequency domain resources as specified in Rel-16.

FIG. 6 illustrates a simplified block diagram of an apparatus for multi-TRP transmission according to some embodiments of the present application. The apparatus 700 may be a BS 101 or a UE 105 (for example, UE 105a, UE 105b, or UE 105c) as shown in FIG. 1.

Referring to FIG. 6, the apparatus 600 may include at least one non-transitory computer-readable medium 62, at least one receiver 64, at least one transmitter 66, and at least one processor 68. In some embodiment of the present application, at least one receiver 64 and at least one transmitter 66 and be integrated into at least one transceiver. The at least one non-transitory computer-readable medium 62 may have computer executable instructions stored therein. The at least one processor 68 may be coupled to the at least one non-transitory computer-readable medium 62, the at least one receiver 64 and the at least one transmitter 66. The computer executable instructions can be programmed to implement a method with the at least one receiver 64, the at least one transmitter 66 and the at least one processor 68. The method can be a method according to an embodiment of the present application, for example, the method shown in FIG. 2.

The method according to embodiments of the present application can also be implemented on a programmed processor. However, the controllers, flowcharts, and modules may also be implemented on a general purpose or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an integrated circuit, a hardware electronic or logic circuit such as a discrete element circuit, a programmable logic device, or the like. In general, any device on which resides a finite state machine capable of implementing the flowcharts shown in the figures may be used to implement the processor functions of this application. For example, an embodiment of the present application provides an apparatus for multi-TRP transmission, including a processor and a memory. Computer programmable instructions for implementing a method for multi-TRP transmission are stored in the memory, and the processor is configured to perform the computer programmable instructions to implement the method for multi-TRP transmission. The method may be a method as stated above or other method according to an embodiment of the present application.

An alternative embodiment preferably implements the methods according to embodiments of the present application in a non-transitory, computer-readable storage medium storing computer programmable instructions. The instructions are preferably executed by computer-executable components preferably integrated with a network security system. The non-transitory, computer-readable storage medium may be stored on any suitable computer readable media such as RAMs, ROMs, flash memory, EEPROMs, optical storage devices (CD or DVD) , hard drives, floppy drives, or any suitable device. The computer-executable component is preferably a processor but the instructions may alternatively or additionally be executed by any suitable dedicated hardware device. For example, an embodiment of the present application provides a non-transitory, computer-readable storage medium having computer programmable instructions stored therein. The computer programmable instructions are configured to implement a method for multi-TRP transmission as stated above or other method according to an embodiment of the present application.

While this application has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Also, all of the elements of each figure are not necessary for operation of the disclosed embodiments. For example, one of ordinary skill in the art of the disclosed embodiments would be enabled to make and use the teachings of the application by simply employing the elements of the independent claims. Accordingly, embodiments of the application as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the application.

Claims

A method, comprising:

receiving downlink control information (DCI) for activating a semi-persistent scheduling (SPS) configuration for a physical downlink shared channel (PDSCH) transmission, wherein the DCI indicates at least one antenna port, and wherein the DCI include a transmission configuration indicator (TCI) codepoint indicating a first set of TCI states;

receiving an activation command, wherein the activation command indicates that the TCI codepoint corresponds to a second set of TCI states; and

determining a third set of TCI states for receiving the PDSCH transmission based on the activation command.
The method of claim 1, wherein the at least one antenna port is antenna ports 0, 2, and 3, and wherein the first set of TCI states includes two TCI states.
The method of claim 2, wherein the second set of TCI states includes one TCI state.
The method of claim 3, wherein determining the third set of TCI states comprises:

determining the third set of TCI states to include two TCI states corresponding to a lowest TCI codepoint of all TCI codepoints corresponding to two TCI states indicated by the activation command.
The method of claim 3, wherein determining the third set of TCI states comprises:

determining the third set of TCI states to include the one TCI state corresponding to the TCI codepoint indicated by the activation command.
The method of claim 2, wherein the second set of TCI states includes two TCI states, and wherein the method further comprises:

determining the third set of TCI states to include two TCI states corresponding to the TCI codepoint indicated by the activation command.
The method of claim 1, wherein the at least one antenna port is included in one code division multiplexing (CDM) group, wherein the first set of TCI states includes one TCI state, wherein a time domain resource assignment (TDRA) field in the DCI indicates an entry in PDSCH time domain allocation list not containing an ultra-reliable and low latency communication (URLLC) repetition number, and wherein a higher layer parameter does not indicate a URLLC repetition scheme.
The method of claim 7, wherein the second set of TCI states includes two TCI states.
The method of claim 8, wherein determining the third set of TCI states comprises:

determining the third set of TCI states to include one TCI state corresponding to a lowest TCI codepoint of all TCI codepoints corresponding to one TCI state indicated by the activation command.
The method of claim 8, wherein determining the third set of TCI states comprises:

determining the third set of TCI states to include a first TCI state of the two TCI states corresponding to the TCI codepoint indicated by the activation command.
The method of claim 7, wherein the second set of TCI states includes one TCI state, and wherein the method further comprises:

determining the third set of TCI states to include one TCI state corresponding to the TCI codepoint indicated by the activation command.
The method of claim 1, wherein the at least one antenna port is included in one CDM group, wherein the first set of TCI states includes two TCI states, and wherein a higher layer parameter indicates a frequency division multiplexing (FDM) repetition scheme.
The method of claim 12, wherein the second set of TCI states includes one TCI state.
The method of claim 13, wherein determining the third set of TCI states comprises:

determining the third set of TCI states to include two TCI states corresponding to a lowest TCI codepoint of all TCI codepoints corresponding to two TCI states indicated by the activation command.
The method of claim 12, wherein the second set of TCI states includes two TCI states, and wherein the method further comprises:

determining the third set of TCI states to include two TCI states corresponding to the TCI codepoint indicated by the activation command.