WO2020143909A1

WO2020143909A1 - Client device and network access node for tci configuration

Info

Publication number: WO2020143909A1
Application number: PCT/EP2019/050391
Authority: WO
Inventors: Wenquan HU; Bengt Lindoff; Panayiotis Papadimitriou; Thorsten Schier; Sha HU
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-01-09
Filing date: 2019-01-09
Publication date: 2020-07-16
Anticipated expiration: 2021-07-09

Abstract

The invention relates to invention relates to a client device and a network access node for transmission configuration indication (TCI) configuration. The client device obtains a transmission configuration indicator, TCI, configuration comprising a set of TCI state sets, wherein each TCI state set comprises at least one TCI state. The client device further obtains a subset of TCI state sets among the set of TCI state sets, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a downlink control information, DCI. The TCI configuration can be transmitted by the network access node in RRC signaling. Thereby, an efficient solution for TCI configuring the client device is provided. Furthermore, the invention also relates to corresponding methods and a computer program.

Description

CLIENT DEVICE AND NETWORK ACCESS NODE FOR TCI CONFIGURATION

Technical Field

The invention relates to a client device and a network access node for TCI configuration of the client device. Furthermore, the invention also relates to corresponding methods and a computer program.

Background

In new radio (NR) a main function of Physical Downlink Control Channel (PDCCH) is to schedule downlink (DL) transmissions on Physical Downlink Shared Channel (PDSCH) and uplink (UL) transmissions on Physical Uplink Shared Channel (PUSCH). The Downlink Control Information (DCI) on the PDCCH includes: Downlink assignments containing at least modulation and coding format, resource allocation, and hybrid-ARQ information related to DL- SCH; and Uplink scheduling grants containing at least modulation and coding format, resource allocation, and hybrid-ARQ information related to UL-SCH.

A User Equipment (UE) monitors a set of PDCCH candidates in configured monitoring occasions in one or more configured COntrol REsource SETs (CORESETs) according to the corresponding search space configurations. A CORESET consists of a set of Physical Resource Blocks (PRBs) with a time duration of 1 to 3 OFDM symbols. The resource units Resource Element Groups (REGs) and Control Channel Elements (CCEs) are defined within a CORESET with each CCE consisting a set of REGs. Control channels are formed by aggregation of CCEs. Different code rates for the control channels are realized by aggregating different number of CCEs. Interleaved and non-interleaved CCE-to-REG mapping are supported in a CORESET and polar coding is used for the PDCCH. Each REG carrying PDCCH carries its own DMRS.

A UE changing its beam or beam link with the network in one cell does not require explicit Radio Resource Control (RRC) signaling to be triggered. The gNB provides via RRC signaling the UE with measurement configuration containing configurations of SSB/CSI resources and resource sets, reports and trigger states for triggering channel and interference measurements and reports. Beam Level Mobility (BLM) is dealt with at lower layers by means of physical layer and Medium Access Control (MAC) layer control signaling, and the RRC is therefore not required to know which beam or beam link is being used at a given point in time. For TCI indication of PDSCH in NR Rel-15 a single TCI state can be indicated to the UE. The UE can be configured with a list of up to M TCI state configurations with the higher layer parameter “PDSCH-Config”, where M depends on the capability of the UE. The TCI state is indicated in a DCI in the PDCCH and is used by the UE to decode the PDSCH. The UE receives an activation command used to map up to 8 TCI states to codepoints, e.g.“000” or“1 1 1 of the DCI field“Transmission Configuration Indication”.

In NR Rel-15, the following Multiple Input Multiple Output (MIMO) features are included: limited support for multi-T ransmission and Reception Point (TRP) or panel operation, flexible Channel State Information (CSI) acquisition and beam management, Type I (low-resolution) and II (high-resolution) codebooks supporting up to 32 ports, and flexible Reference Signals (RSs) for MIMO transmission, especially CSI-RS, DMRS, and SRS. One aspect that can be enhanced is to support multi-TRP or panel transmission including improved reliability and robustness with both ideal and non-ideal backhaul. A design target is to specify DL control signaling enhancement(s) for efficient support of non-coherent joint transmission in multi TRP, panel or beam scenarios.

Summary

An objective of embodiments of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

Another objective of embodiments of the invention is to provide efficient TCI configuration of client devices in a wireless communication system.

The above and further objectives are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

According to a first aspect of the invention, the above mentioned and other objectives are achieved with a client device for a wireless communication system, the client device being configured to

obtain a transmission configuration indicator, TCI, configuration comprising a set of TCI state sets, wherein each TCI state set comprises at least one TCI state;

obtain a subset of TCI state sets among the set of TCI state sets, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a downlink control information, DCI. An advantage of the client device according to the first aspect is that an efficient solution for TCI configuring the client device is provided. Through this TCI configuration of the client device, multiple TCI states can be indicated with less control overhead in the physical layer.

In an implementation form of a client device according to the first aspect, each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of the DCI according to a predefined rule.

The predefined rule can be given in a standard such as 3GPP NR.

An advantage with this implementation form is that the client device easily can detect which TCI state that is used for data reception. Further, less overhead in control signaling is introduced to indicate a specific TCI state.

In an implementation form of a client device according to the first aspect, the client device is further configured to

obtain a default TCI state set for each TCI state mapped onto codepoints associated with a TCI state set comprising more than one TCI state.

A default TCI state set herein is a TCI state set that is pre-configured prior to any later TCI state set indications received from the network access node. Until no explicit indication of a TCI state set has been received, the default TCI state set will be applied by the client device.

An advantage with this implementation form is that the client device knows which TCI state set to use when no explicit indication has been received, thereby giving the client device the possibility of optimized data reception.

In an implementation form of a client device according to the first aspect, a default TCI state set for a TCI state is a TCI state set comprising the TCI state set if the TCI state is only mapped onto one codepoint associated with a TCI state set.

An advantage with this implementation form is that the client device can determine the default TCI state set without any signaling from the network access node, thereby saving radio resources. In an implementation form of a client device according to the first aspect, the client device is further configured to

obtain a default TCI state set for a TCI state in explicit signaling if the TCI state is mapped onto more than one codepoint associated with a TCI state set.

An advantage with this implementation form is that the client device can determine the default TCI state in a simple way and thereby does not need to perform any blind detection and hence saving processing power. Further, the performance of the data reception is guaranteed under the control of the network access node.

In an implementation form of a client device according to the first aspect, obtain the default TCI state set in explicit signaling comprises

receive the default TCI state set in radio resource control, RRC, signaling or in medium access control, MAC, signaling from a network access node.

An advantage with this implementation form is that this control signaling can be performed as higher layer signaling and it can be applied by the client device when triggered by such signaling, thereby saving radio resources compared to the case of using lower layer control signaling.

receive a DCI associated with a set of data channels or a set of layers of a data channel; decode the TCI field of the received DCI so as to obtain a codepoint;

derive TCI state set information for the set of data channels or the set of layers of the data channel based on the obtained codepoint;

receive data transmissions in the set of data channels or the set of layers of the data channel according to the obtained TCI state set information.

An advantage with this implementation form is that the client device without blind detection can determine which TCI state that is used for the data reception and thereby optimize the data reception performance without the use of excessive processing power.

In an implementation form of a client device according to the first aspect, the obtained TCI state set information is at least one of: quasi-collocation, QCL, information; spatial filter parameters; and beam link information. An advantage with this implementation form is that the client device then can adapt receiver beam settings for optimized data reception.

In an implementation form of a client device according to the first aspect, obtain the TCI configuration comprises

receive the TCI configuration in RRC signaling from a network access node.

An advantage with this implementation form is that the control signaling is made by high layer signaling thereby flexible scheduling is achieved.

In an implementation form of a client device according to the first aspect, obtain the subset of TCI state sets comprises

obtain the subset of the set of TCI state sets based on an activation status vector.

An advantage with this implementation form is that the client device knows which subset of TCI state sets than can be used for data reception, thereby reducing the processing complexity in the client device.

receive the activation status vector in MAC signaling from a network access node.

An advantage with this implementation form is that the control signaling is made by MAC signaling thereby lower latency can be achieved compared to using RRC signaling.

In an implementation form of a client device according to the first aspect, the set of TCI state sets comprises at least two groups of TCI state sets, and wherein TCI state sets in a group of TCI state sets comprises the same number of TCI states and two TCI state sets from different groups of TCI state sets comprises different number of TCI states.

An advantage with this implementation form is that more TCI state sets can be candidates in the physical layer for physical layer indication as the set of TCI state sets are divided into at least two groups of TCI state sets. In an implementation form of a client device according to the first aspect, the client device is further configured to

obtain an indication for deriving one activated group of TCI state sets among the at least two groups of TCI state sets.

An advantage with this implementation form is that the client device knows in advance how many TCI states is to be indicated and therefore can tune radio parameters to the current TCI state information and thereby save processing power.

In an implementation form of a client device according to the first aspect, obtain the indication comprises

receive the indication in MAC signaling from a network access node.

An advantage with this implementation form is that lower latency can be achieved by the use of MAC signaling compared to using RRC signaling.

In an implementation form of a client device according to the first aspect, the set of TCI state sets comprises a single group of TCI state sets, and wherein at least two TCI state sets in the single group of TCI state sets comprises different number of TCI states.

An advantage with this implementation form is that less signaling is needed since beam rank indication is not needed.

According to a second aspect of the invention, the above mentioned and other objectives are achieved with a network access node for a wireless communication system, the network access node being configured to

transmit a TCI configuration comprising a set of TCI state sets to a client device, wherein each TCI state set comprises at least one TCI state, and wherein a subset of TCI state sets among the set of TCI state sets is indicated, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a DCI.

An advantage of the network access node according to the second aspect is that an efficient solution for TCI configuring the client device is provided. Through this TCI configuration of the client device, multiple TCI states can be indicated with less control overhead in the physical layer. In an implementation form of a network access node according to the second aspect, each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of the DCI according to a predefined rule.

In an implementation form of a network access node according to the second aspect, the network access node is further configured to

transmit a default TCI state set in RRC signaling or in MAC signaling to the client device.

In an alternative, the client device can be implicitly configured with the default TCI state set which means that signaling from the network access node is not needed in this respect.

An advantage with this implementation form is that the client device will know which TCI state set to use when no explicit indication has been received, thereby giving the client device the possibility of optimized data reception.

In an implementation form of a network access node according to the second aspect, transmit the TCI configuration comprises

transmit the TCI configuration in RRC signaling.

transmit an activation status vector in MAC signaling to the client device, wherein the activation status vector indicates the subset of the set of TCI state sets.

An advantage with this implementation form is that the client device will know which subset of TCI state sets than can be used for data reception, reducing the processing complexity in the client device. In an implementation form of a network access node according to the second aspect, the set of TCI state sets comprises at least two groups of TCI state sets, and wherein TCI state sets in a group of TCI state sets comprises the same number of TCI states and two TCI state sets from different groups of TCI state sets comprises different number of TCI states.

An advantage with this implementation form is that more TCI state sets can be candidates in the physical layer for physical layer indication as the set of TCI state sets are divided into at least two groups of TCI state sets.

transmit an indication of which one of the at least two groups of TCI state sets that is active to the client device.

An advantage with this implementation form is that the client device will know in advance how many TCI states is to be indicated and therefore can tune radio parameters to the current TCI state information and thereby saving processing power.

In an implementation form of a network access node according to the second aspect, transmit the indication comprises

transmit the indication in MAC signaling.

In an implementation form of a network access node according to the second aspect, the set of TCI state sets comprises a single group of TCI state sets, and wherein at least two TCI state sets in the single group of TCI state sets comprises different number of TCI states.

According to a third aspect of the invention, the above mentioned and other objectives are achieved with a method for a client device, the method comprises

obtaining a transmission configuration indicator, TCI, configuration comprising a set of TCI state sets, wherein each TCI state set comprises at least one TCI state; obtaining a subset of TCI state sets among the set of TCI state sets, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a downlink control information, DCI.

The method according to the third aspect can be extended into implementation forms corresponding to the implementation forms of the client device according to the first aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the client device.

The advantages of the methods according to the third aspect are the same as those for the corresponding implementation forms of the client device according to the first aspect.

According to a fourth aspect of the invention, the above mentioned and other objectives are achieved with a method for a network access node, the method comprises

transmitting a TCI configuration comprising a set of TCI state sets to a client device, wherein each TCI state set comprises at least one TCI state, and wherein a subset of TCI state sets among the set of TCI state sets is indicated, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a DCI.

The method according to the fourth aspect can be extended into implementation forms corresponding to the implementation forms of the network access node according to the second aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the network access node.

The advantages of the methods according to the fourth aspect are the same as those for the corresponding implementation forms of the network access node according to the second aspect.

The invention also relates to a computer program, characterized in program code, which when run by at least one processor causes said at least one processor to execute any method according to embodiments of the invention. Further, the invention also relates to a computer program product comprising a computer readable medium and said mentioned computer program, wherein said computer program is included in the computer readable medium, and comprises of one or more from the group: ROM (Read-Only Memory), PROM (Programmable ROM), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically EPROM) and hard disk drive.

Further applications and advantages of the embodiments of the invention will be apparent from the following detailed description.

Brief Description of the Drawings

The appended drawings are intended to clarify and explain different embodiments of the invention, in which:

- Fig. 1 shows a client device according to an embodiment of the invention;

- Fig. 2 shows a method for a client device according to an embodiment of the invention;

- Fig. 3 shows a network access node according to an embodiment of the invention;

- Fig. 4 shows a method for a network access node according to an embodiment of the invention;

- Fig. 5 shows a wireless communication system according to an embodiment of the invention;

- Fig. 6a and 6b illustrate single DCI scheduling of multibeam transmissions in two different transmission scenarios;

- Fig. 7 illustrates an embodiment of the invention;

- Fig. 8 illustrates a further embodiment of the invention; and

- Fig. 9 illustrates a further embodiment of the invention.

Detailed Description

Ultra Reliable and Low Latency Communication (URLLC) is an important service scenario introduced in NR. In this respect multiple-TRP or multiple-beam based data transmissions will be a useful technique to support such URLLC services. Therefore, the inventors have realized the need for an efficient TCI configuration of UEs. Especially, a mechanism for efficient TCI configuration indication for multiple PDSCHs is of high importance.

Fig. 1 shows a client device 100 according to an embodiment of the invention. In the embodiment shown in Fig. 1 , the client device 100 comprises a processor 102, a transceiver 104 and a memory 106. The processor 102 is coupled to the transceiver 104 and the memory 106 by communication means 108 known in the art. The client device 100 further comprises an antenna or antenna array 1 10 coupled to the transceiver 104, which means that the client device 100 is configured for wireless communications in a wireless communication system. That the client device 100 is configured to perform certain actions can in this disclosure be understood to mean that the client device 100 comprises suitable means, such as e.g. the processor 102 and the transceiver 104, configured to perform said actions.

According to embodiments of the invention the client device 100 is configured to obtain a TCI configuration comprising a set of TCI state sets. Each TCI state set comprises at least one TCI state. The client device 100 is further configured to obtain a subset of TCI state sets among the set of TCI state sets. The subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a DCI.

Fig. 2 shows a flow chart of a corresponding method 200 which may be executed in a client device 100, such as the one shown in Fig. 1. The method 200 comprises obtaining 202 a TCI configuration comprising a set of TCI state sets, wherein each TCI state set comprises at least one TCI state. The method 200 further comprises obtaining 204 a subset of TCI state sets among the set of TCI state sets, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a DCI .

Fig. 3 shows a network access node 300 according to an embodiment of the invention. In the embodiment shown in Fig. 3, the network access node 300 comprises a processor 302, a transceiver 304 and a memory 306. The processor 302 is coupled to the transceiver 304 and the memory 306 by communication means 308 known in the art. The network access node 300 may be configured for both wireless and wired communications in wireless and wired communication systems, respectively. The wireless communication capability is provided with an antenna or antenna array 310 coupled to the transceiver 304, while the wired communication capability is provided with a wired communication interface 312 coupled to the transceiver 304. The antenna array is configured for MIMO transmission using multiple beams, multiple beams links or multiple panels known in the art. Further, the network access node 300 can comprise one or more TRPs for communication with client devices.

That the network access node 300 is configured to perform certain actions can in this disclosure be understood to mean that the network access node 300 comprises suitable means, such as e.g. the processor 302 and the transceiver 304, configured to perform said actions. According to embodiments of the invention, the network access node 300 is configured to transmit a TCI configuration comprising a set of TCI state sets to a client device 100. Each TCI state set comprises at least one TCI state, and wherein a subset of TCI state sets among the set of TCI state sets is indicated. The subset of TCI state sets comprises activated TCI state sets, and each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a DCI.

Fig. 4 shows a flow chart of a corresponding method 400 which may be executed in a network access node 300, such as the one shown in Fig. 3. The method 400 comprises transmitting 402 a TCI configuration comprising a set of TCI state sets to a client device 100. Each TCI state set comprises at least one TCI state, and wherein a subset of TCI state sets among the set of TCI state sets is indicated. The subset of TCI state sets comprises activated TCI state sets, and each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a DCI.

Fig. 5 shows a wireless communication system 500 according to an embodiment of the invention. The wireless communication system 500 comprises a client device 100 and a network access node 300 configured to operate in the wireless communication system 500. For simplicity, the wireless communication system 500 shown in Fig. 5 only comprises one client device 100 and one network access node 300. However, the wireless communication system 500 may comprise any number of client devices 100 and any number of network access nodes 300 without deviating from the scope of the invention.

In the wireless communication system 500, the client device 100 is configured to obtain TCI configuration for UL or DL data transmission in data channels, such as PDSCH and PUSCH. According to an embodiment of the invention, the TCI configuration is obtained by the client device 100 through RRC signaling from the network access node 300 as illustrated in Fig. 5. Hence, the subset of TCI state sets is selected by the network access node 300 when TCI configuration is signaled to the client device 100.

Generally, the client device 100 receives a DCI associated with a set of data channels or alternatively a set of layers of a data channel (e.g. PDSCH and PUSCH) and addressed to the client device 100. The TCI field of the received DCI is decoded so that the client device 100 obtains a codepoint which is used for deriving TCI state set information for the set of data channels or the set of layers of the data channel. Finally, the client device 100 receives DL data transmission(s) in the set of data channels according to the obtained TCI state set information. The obtained TCI state set information can be at least one of: quasi-collocation (QCL) information; spatial filter parameters; and beam link information for the data transmissions in the set of data channels. Hence, the client device 100 tunes its receiver block to the mentioned TCI state set information for receiving the DL data transmission.

Regarding the subset of TCI state sets, the client device 100 can obtain the subset of the set of TCI state sets based on an activation status vector in bitmap form. According to an embodiment of the invention, the client device 100 is configured to receive the activation status vector in MAC signaling, e.g. in a MAC CE, from the network access node 300 as shown in Fig. 5.

Fig. 6a and 6b illustrate two non-limiting exemplary network deployments in which embodiments of the invention can be applied. In Fig. 6a and 6b two PDSCHs are transmitted to the client device 100 through two different beams associated with two different PDSCH, i.e. PDSCH1 and PDSCH2. The client device 100 is however scheduled by a single PDCCH transmitted from one TRP, i.e. TRP1 , in the example in Fig. 6a. In an alternative as shown in Fig. 6b PDSCH 1 and PDSCH2 are transmitted from two respective TRPs, i.e. TRP1 and TRP2, however scheduled by a single PDCCH transmitted from TRP1.

In an embodiment of the invention, the client device 100 is configured with one or more TCI state set groups or sequences, where each TCI state set comprises one or more TCI states. A beam rank is the number of TCI states in one TCI state set. The TCI state set groups can be generated by the network access node 300, e.g. based on CSI feedback from the client device 100.

Fig. 7 illustrates an embodiment of the invention. According to this embodiment, the client device 100 is configured with one TCI state set for each beam rank. Hence, the set of TCI state sets comprises at least two groups of TCI state sets, and TCI state sets in a group of TCI state sets comprises the same number of TCI states and two TCI state sets from different groups of TCI state sets comprises different number of TCI states.

For a specific beam rank, a MAC activation command (e.g. MAC CE) is used to map a number of TCI state sets to codepoints of the DCI field’’Transmission Configuration Indication”. The beam rank can be indicated to the client device 100 by another MAC CE command about how many TCI states will be scheduled in a single DCI. In RRC signaling, for beam rank 1 , i.e. the single beam case, existing method can be adopted to configure the TCI state information for PDSCH. For beam rank 2 the following RRC configuration can be used to configure possible TCI state set sequence/candidate:

tci-StatesToAddModl_istBeamrank2 SEQUENCE (SIZE(1..maxNrofTCI-State-Sets)) OF TCI-State set

where tci-StatesToAddModl_istBeamrank2 is a sequence type signaling and elements of the SEQUENCE are the TCI state sets, maxNrofTCI-State-Sets defines the largest size of signaling, and OF TCI-State set defines the property of the signaling.

Further, a MAC CE command can be used to activate a subset of the set of TCI state sets and map the activated subset of TCI state sets to the codepoints of the DCI field“Transmission Configuration Indication” for one beam rank. Once the client device 100 knows the beam rank and the indicated value in the DCI field “Transmission Configuration Indication”, the client device 100 knows the indicated TCI information for the scheduled PDSCH(s).

In step I) of Fig. 7, the client device 100 becomes RCI configured with a set of TCI state sets by RRC signaling, one per beam rank, from a network access node 300. The TCI state sets are grouped according to the number of TCI states in a TCI set. Fig. 7 shows two TCI state set groups, i.e. TCI state set group 1 and TCI state set group 2. The client device 100 can obtain an indication for deriving one activated group of TCI state sets among the at least two groups of TCI state sets, e.g. in MAC CE signaling from a network access node 300.

In step II) of Fig. 7, the client device 100 therefore receives a MAC CE used to activate a specific beam rank and a subset of the set of TCI state sets, i.e. TO, T1. T(N-1 ). The activated subset of TCI state sets is mapped to codepoints of the DCI field“Transmission Configuration Indication”, starting from the first activated TCI state set, i.e. T1 in this example. The client device 100 detects a“Transmission Configuration Indication” in a DCI with bitmap Ό00’, given that beam rank 2 is activated.

In step III) of Fig. 7, the client device 100 derives TCI information for the set of data channels based on the codepoint, in this example the client device 100 knows there are two QCL information which are Beam #3 and Beam #5 for the associated set of data channels.

Fig. 8 illustrates a further embodiment of the invention. According to this embodiment, a client device 100 is configured with one TCI state set group, where some TCI state sets in the group have a first beam rank and other TCI state sets in the group have a second beam rank. In other words, the set of TCI state sets comprises a single group of TCI state sets, and at least two TCI state sets in the single group of TCI state sets comprises different number of TCI states.

In RRC signaling, the following RRC configuration can be updated to configure a TCI state set group to the client device 100:

tci-StatesToAddModList SEQUENCE (SIZE(1..maxNrofTCI-State-sets)) OF TCI- State set OPTIONAL

where tci-StatesToAddModList is an updated signaling extending the current TCI signaling in NR Rel 15.

As previously mentioned, a MAC CE command can be used to activate a subset of TCI state sets among the set of TCI state sets and map the activated subset of TCI state sets to the codepoints of the DCI field“Transmission Configuration Indication”. Once the client device 100 knows the indicated value in DCI field“Transmission Configuration Indication”, the client device 100 knows the indicated TCI information for the scheduled PDSCHs.

In step I) of Fig. 8, in the RRC layer a group of TCI state sets are configured for the client device 100 by RRC signaling from the network access node 300.

In step II) of Fig. 8, in the MAC layer a MAC CE command can be used to activate a subset of TCI state sets and map these TCI state sets to codepoints of the DCI field“Transmission Configuration Indication” starting from the first activated TCI state set.

In step III) of Fig. 8, the client device 100 detects a“Transmission Configuration Indication” with bitmap Ό00T in a DCI, and therefore knows that there are two QCL information corresponding to Beam #2 and Beam #3 for the associated two PDSCHs or two layers of a single PDSCH.

Fig. 9 illustrates a further embodiment of the invention. According to this embodiment, for each beam rank larger than 1 , and for each TCI state there is a default TCI state set. This means that one TCI state in a TCI state set will be associated with other TCI states in a beam set through this default TCI state set. In other words, a default TCI state set for a TCI state is a TCI state set comprising the TCI state set if the TCI state is only mapped onto one codepoint associated with a TCI state set. According to an embodiment of the invention, the client device 100 obtains a default TCI state set for a TCI state in explicit signaling if the TCI state is mapped onto more than one codepoint associated with a TCI state set. The default TCI state set can be received in RRC signaling or MAC signaling from a network access node 300.

For example, by considering the following codepoint/beam(s) in Table 1 it is concluded that codepoints 101 , 110 and 1 11 comprises two beams each. It is further noted that beam Beam #3 is both in 101 and 110 which means that explicit signaling is needed so that the client device 100 can determine which one of 101 or 1 10 is the default TCI state set for Beam #3, i.e. set Beam #3 and Beam #4 or Beam #3 and Beam #5.

Table 1

When high layer signaling parameter“tci-PresentlnDCI” is not configured for the CORESET scheduling the PDSCH, or the PDSCH is scheduled by a DCI format 1_0. For determining multiple PDSCHs’ antenna port quasi co-location (QCL), the client device 100 assumes that the TCI state for the PDSCH is dependent on the TCI state applied for the CORESET used for the PDCCH transmission and a default TCI state set. When the scheduling offset between the PDSCH and the DCI is less than a certain threshold, the default QCL assumption follows the TCI state of the CORESET with the lowest identity (ID) in the latest slot in which one or more CORESETs are configured and a corresponding default TCI state set of that default QCL assumption. For transmission of a set of layers of a single PDSCH from multiple TRPs, the above embodiment can be applied.

In step I) of Fig. 9, in the RRC layer two groups of TCI state sets. i.e. TCI state set group 1 and TCI state set group 2, are configured for the client device 100 by RRC signaling from the network access node 300. In step II) of Fig. 9, among all the activated TCI state sets which are mapped to the DCI field and with beam rank larger than 1 , each TCI state corresponds to a default TCI state set. In this example, for Beam #3, there are two TCI state sets, i.e. Set2 and Set4, comprising Beam #3, wherein Set2 is configured as a default TCI state set for Beam #3. The same logic applies to the other beams and can be configured with its own default TCI state set.

In step III) of Fig. 9, when the client device 100 detects a PDCCH, the client device 100 in step Ilia) derives a default QCL assumption for a first data channel from the PDCCH. Based on the derived default QCL assumption for the first data channel and the default TCI state set corresponding to the derived default QCL assumption, the client device 100 in step Nib) can derive the QCL assumption for a second data channel (or further data channels) in the set of data channels associated with the PDCCH. In the example in Fig. 9, if a PDCCH is detected on Beam #3, the client device 100 will derive the TCI state with Beam #3 for a PDSCH transmitted from a TRP, the another PDSCH transmitted from another TRP will be from Beam #5.

The client device 100 herein, may be denoted as a user device, a User Equipment (UE), a mobile station, an internet of things (loT) device, a sensor device, a wireless terminal and/or a mobile terminal, is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The UEs may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The UEs in this context may be, for example, portable, pocket-storable, hand-held, computer- comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another receiver or a server. The UE can be a Station (STA), which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM). The UE may also be configured for communication in 3GPP related LTE and LTE-Advanced, in WiMAX and its evolution, and in fifth generation wireless technologies, such as New Radio.

The network access node 300 herein may also be denoted as a radio network access node, an access network access node, an access point, or a base station, e.g. a Radio Base Station (RBS), which in some networks may be referred to as transmitter,“gNB”,“gNodeB”,“eNB”, “eNodeB”,“NodeB” or“B node”, depending on the technology and terminology used. The radio network access nodes may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. The radio network access node can be a Station (STA), which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM). The radio network access node may also be a base station corresponding to the fifth generation (5G) wireless systems.

Furthermore, any method according to embodiments of the invention may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprise essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.

Moreover, it is realized by the skilled person that embodiments of the client device 100 and the network access node 300 comprises the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the solution. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, MSDs, TCM encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged togetherfor performing the solution.

Especially, the processor(s) of the client device 100 and the network access node 300 may comprise, e.g., one or more instances of a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The expression “processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

Finally, it should be understood that the invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

1 . A client device (100) for a wireless communication system (500), the client device (100) being configured to

obtain a subset of TCI state sets among the set of TCI state sets, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a downlink control information, DCI.

2. The client device (100) according to claim 1 , wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of the DCI according to a predefined rule.

3. The client device (100) according to claim 2, configured to

4. The client device (100) according to claim 3, wherein a default TCI state set for a TCI state is a TCI state set comprising the TCI state set if the TCI state is only mapped onto one codepoint associated with a TCI state set.

5. The client device (100) according to claim 3 or 4, configured to

6. The client device (100) according to claim 5, wherein obtain the default TCI state set in explicit signaling comprises

receive the default TCI state set in radio resource control, RRC, signaling or in medium access control, MAC, signaling from a network access node (300).

7. The client device (100) according to any of the preceding claims, configured to

derive TCI state set information for the set of data channels or the set of layers of the data channel based on the obtained codepoint; receive data transmissions in the set of data channels or the set of layers of the data channel according to the obtained TCI state set information.

8. The client device (100) according to claim 7, wherein the obtained TCI state set information is at least one of: quasi-collocation, QCL, information; spatial filter parameters; and beam link information.

9. The client device (100) according to any of the preceding claims, wherein obtain the TCI configuration comprises

receive the TCI configuration in RRC signaling from a network access node (300).

10. The client device (100) according to any of the preceding claims, wherein obtain the subset of TCI state sets comprises

1 1. The client device (100) according to claim 10, configured to

receive the activation status vector in MAC signaling from a network access node (300).

12. The client device (100) according to any of claims 1 to 1 1 , wherein the set of TCI state sets comprises at least two groups of TCI state sets, and wherein TCI state sets in a group of TCI state sets comprises the same number of TCI states and two TCI state sets from different groups of TCI state sets comprises different number of TCI states.

13. The client device (100) according to claim 12, configured to

14. The client device (100) according to claim 13, wherein obtain the indication comprises receive the indication in MAC signaling from a network access node (300).

15. The client device (100) according to any of claims 1 to 1 1 , wherein the set of TCI state sets comprises a single group of TCI state sets, and wherein at least two TCI state sets in the single group of TCI state sets comprises different number of TCI states.

16. A network access node (300) for a wireless communication system (500), the network access node (300) being configured to transmit a TCI configuration comprising a set of TCI state sets to a client device (100), wherein each TCI state set comprises at least one TCI state, and wherein a subset of TCI state sets among the set of TCI state sets is indicated, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a DCI.

17. The network access node (300) according to claim 16, wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of the DCI according to a predefined rule.

18. The network access node (300) according to claim 17, configured to

transmit a default TCI state set in RRC signaling or in MAC signaling to the client device

(100).

19. The network access node (300) according to any of claims 16 to 18, wherein transmit the TCI configuration comprises

transmit the TCI configuration in RRC signaling.

20. The network access node (300) according to any of claims 16 to 18, configured to

transmit an activation status vector in MAC signaling to the client device (100), wherein the activation status vector indicates the subset of the set of TCI state sets.

21 . The network access node (300) according to any of claims 16 to 20, wherein the set of TCI state sets comprises at least two groups of TCI state sets, and wherein TCI state sets in a group of TCI state sets comprises the same number of TCI states and two TCI state sets from different groups of TCI state sets comprises different number of TCI states.

22. The network access node (300) according to claim 21 , configured to

transmit an indication of which one of the at least two groups of TCI state sets that is active to the client device (100).

23. The network access node (300) according to claim 22, wherein transmit the indication comprises

transmit the indication in MAC signaling.

24. The network access node (300) according to any of claims 16 to 20, wherein the set of TCI state sets comprises a single group of TCI state sets, and wherein at least two TCI state sets in the single group of TCI state sets comprises different number of TCI states. 25. A method (200) for a client device (100), the method (200) comprises

obtaining (202) a transmission configuration indicator, TCI, configuration comprising a set of TCI state sets, wherein each TCI state set comprises at least one TCI state;

obtaining (204) a subset of TCI state sets among the set of TCI state sets, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a downlink control information, DCI.

26. A method (400) for a network access node (300), the method (400) comprising

transmitting (402) a TCI configuration comprising a set of TCI state sets to a client device (100), wherein each TCI state set comprises at least one TCI state, and wherein a subset of

TCI state sets among the set of TCI state sets is indicated, wherein the subset of TCI state sets comprises activated TCI state sets, and wherein each TCI state set in the subset of TCI state sets is mapped onto a codepoint of a TCI field of a DCI. 27. A computer program with a program code for performing a method according to claim 25 or 26 when the computer program runs on a computer.