ACTIVATION OF TWO OR MORE TCI CONDITIONS FOR ONE OR MORE CORE SETS

Description

Related Applications

[0001] This application claims the benefit of provisional patent application serial number 63 / 038,385, filed June 12, 2020.Technical Field

[0002] The present disclosure relates to Transmission Configuration Indicator (TCI) state activation in a cellular communications system.Background

[0003] The next generation mobile wireless communication system (5G), or New Radio (NR), will support a diverse set of use cases and a diverse set of deployment scenarios. The later includes deployment at both low frequencies (below 6 Gigahertz (GHz)) and very high frequencies (up to 10's of GHz).NR Frame Structure and Resource Grid

[0004] NR uses Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) in both downlink (i.e., from a network node, gNB, or base station, to a user equipment or UE) and uplink (i.e., from UE to gNB). Discrete Fourier Transform (DFT) spread Orthogonal Frequency Division Multiplexing (OFDM) is also supported in the uplink. In the time domain, NR downlink and uplink are organized into equally-sized subframes of 1 millisecond (ms) each. A subframe is further divided into multiple slots of equal duration. The slot length depends on subcarrier spacing. For subcarrier spacing of Δf = 15 kilohertz (kHz), there is only one slot per subframe, and each slot consists of 14 OFDM symbols.

[0005] Data scheduling in NR is typically on a slot basis. An example is shown in Figure 1 with a 14-symbol slot, where the first two symbols contain Physical Downlink Control Channel (PDCCH), and the rest of the symbols contain physical shared data channel, either Physical Downlink Shared Channel (PDSCH) or Physical Uplink Shared Channel (PUSCH).

[0006] Different subcarrier spacing values are supported in NR. The supported subcarrier spacing values (also referred to as different numerologies) are given by Δf = (15 × 2 µ< )kHz where µ ∈ 0,1,2,3,4. Δf = 15kHz is the basic subcarrier spacing. The slot durations at different subcarrier spacings is given by 1 2 μ ms.

[0007] In the frequency domain, a system bandwidth is divided into resource blocks (RBs), each corresponding to twelve contiguous subcarriers. The RBs are numbered starting with 0 from one end of the system bandwidth. The basic NR physical time-frequency resource grid is illustrated in Figure 2, where only one RB within a 14-symbol slot is shown. One OFDM subcarrier during one OFDM symbol interval forms one resource element (RE).

[0008] Downlink (DL) transmissions can be dynamically scheduled, i.e., in each slot the gNB transmits Downlink Control Information (DCI) over Physical Downlink Control Channel (PDCCH) about which UE data is to be transmitted to and which RBs in the current downlink slot the data is transmitted on. The UE data is carried on PDSCH.

[0009] There are three DCI formats defined for scheduling PDSCH in NR, i.e., DCI format 1_0, DCI format 1_1, and DCI format 1_2. DCI format 1_0 has a smallest size and can be used when a UE is not fully connected to the network, while DCI format 1_1 can be used for scheduling Multiple-Input-Multiple-Output (MIMO) transmissions with two transport blocks (TBs). DCI format 1_2 supports configurable sizes for some fields in the DCI so that a smaller DCI size than DCI format 1_1 can be configured.

[0010] In downlink, a UE first detects and decodes a PDCCH and, if the decoding is successful, the UE then decodes the corresponding PDSCH based on the decoded control information in the PDCCH.

[0011] Similar to downlink, uplink transmission can be dynamically scheduled in which a UE first decodes uplink grants in a PDCCH and then transmits data over PUSCH based the decoded control information in the uplink grant such as modulation order, coding rate, uplink resource allocation, etc.QCL and TCI states

[0012] Several signals can be transmitted from different antenna ports of a same base station. These signals can have the same large-scale properties such as Doppler shift / spread, average delay spread, or average delay. These antenna ports are then said to be Quasi Co-Located (QCL). Note that "QCL" is sometimes also used herein to refer to "Quasi Co-Location."

[0013] If the UE knows that two antenna ports are QCL with respect to a certain parameter (e.g., Doppler spread), the UE can estimate that parameter based on one of the antenna ports and apply that estimate for receiving signal on the other antenna port. Typically, the first antenna port is represented by a measurement reference signal such as Channel State Information Reference Signal (CSI-RS) or Synchronization Signal Block (SSB), known as a source RS, and the second antenna port is a Demodulation Reference Signal (DMRS), known as a target RS.

[0014] For instance, if antenna ports A and B are QCL with respect to average delay, the UE can estimate the average delay from the signal received from antenna port A and assume that the signal received from antenna port B has the same average delay. This is useful for demodulation since the UE can know beforehand the properties of the channel, which for instance helps the UE in selecting an appropriate channel estimation filter.

[0015] Information about what assumptions can be made regarding QCL is signaled to the UE from the network. In NR, four types of QCL relations between a transmitted source RS and transmitted target RS are defined: Type A: {Doppler shift, Doppler spread, average delay, delay spread}, Type B: {Doppler shift, Doppler spread}, Type C: {average delay, Doppler shift}, and Type D: {Spatial Rx parameter}.

[0016] QCL type D was introduced to facilitate beam management with analog beamforming and is known as spatial QCL. There is currently no strict definition of spatial QCL, but the understanding is that if two transmitted antenna ports are spatially QCL, the UE can use the same Rx beam to receive them.

[0017] For dynamic beam and Transmission / Reception Point (TRP) selection, a UE can be configured through RRC signaling with up to one-hundred and twenty-eight (128) Transmit Configuration Indicator (TCI) states for PDSCH in frequency range 2 (FR2) and up to eight (8) TCI states in FR1, depending on UE capability.

[0018] Each TCI state contains QCL information, i.e. one or two source DL RSs, each source RS associated with a QCL type. For example, a TCI state contains a pair of reference signals, each associated with a QCL type, e.g. two different CSI-RSs {CSI-RS1, CSI-RS2} are configured in the TCI state as {qcl-Type1,qcl-Type2} = {Type A, Type D}. This means the UE can derive Doppler shift, Doppler spread, average delay, delay spread from CSI-RS1 and Spatial Rx parameter (i.e., the RX beam to use) from CSI-RS2.

[0019] The list of TCI states can be interpreted as a list of possible beams transmitted from the network or a list of possible TRPs used by the network to communicate with the UE.

[0020] For PDSCH transmission, up to eight (8) TCI states or pairs of TCI states may be activated, and a UE may be dynamically indicated by a TCI codepoint in DCI one or two of the activated TCI states for PDSCH reception. The UE uses the TCI-State according to the value of the 'Transmission Configuration Indication' field in the detected PDCCH with DCI for determining PDSCH antenna port quasi co-location.Default TCI State(s) for PDSCH

[0021] If none of the TCI codepoints are mapped to more than a single TCI state and the offset between the reception of a DL DCI and the corresponding PDSCH is less than a threshold timeDurationForQCL configured by higher layers, the UE may assume that the DM-RS ports of PDSCH of a serving cell are quasi co-located with the RS(s) with respect to the QCL parameter(s) used for PDCCH quasi co-location indication of the CORESET associated with a monitored search space with the lowest CORESET-ID in the latest slot in which one or more CORESETs within the active BWP of the serving cell are monitored by the UE. Here the QCL parameter(s) used for PDCCH may refer to the source RS(s) and the corresponding QCL type(s) specified in the TCI state activated for the CORESET. The TCI state may be referred to as the default TCI state for PDSCH. In other words, the UE may apply QCL type-D property of the TCI state in a slot for receiving PDSCH before decoding the corresponding PDCCH. After a PDCCH is decoded successfully and if the offset indicated in the corresponding DCI is less than the threshold, the UE may apply also other QCL properties of the TCI state in decoding the PDSCH.

[0022] If the offset between the reception of the DL DCI and the corresponding PDSCH is less than the threshold timeDurationForQCL and at least one configured TCI states for the serving cell of scheduled PDSCH contains the 'QCL-TypeD', and at least one TCI codepoint indicates two TCI states, the UE may assume that the DM-RS ports of PDSCH of a serving cell are quasi co-located with the RS(s) with respect to the QCL parameter(s) associated with the TCI states corresponding to the lowest codepoint among the TCI codepoints containing two different TCI states. The two TCI states may then be the default TCI states for PDSCH.

[0023] For a UE configured by higher layer parameter PDCCH-Config that contains two different values of CORESETPoolIndex in ControlResourceSet, if the offset between the reception of the DL DCI and the corresponding PDSCH is less than the threshold timeDurationForQCL, the UE may assume that the DM-RS ports of PDSCH associated with a value of CORESETPoolIndex of a serving cell are quasi co-located with the RS(s) with respect to the QCL parameter(s) used for PDCCH quasi co-location indication of the CORESET associated with a monitored search space with the lowest CORESET-ID among CORESETs, which are configured with the same value of CORESETPoolIndex as the PDCCH scheduling that PDSCH, in the latest slot in which one or more CORESETs associated with the same value of CORESETPoolIndex as the PDCCH scheduling that PDSCH within the active BWP of the serving cell are monitored by the UE. The TCI state activated for the CORESET may then be the default TCI state for PDSCH scheduled by PDCCH in CORESET(s) with the same value of CORESETPoolIndex.CORESET and TCI States for PDCCH

[0024] In Radio Resource Control (RRC), see Third Generation Partnership Project (3GPP) Technical Specification (TS) 38.331 (e.g., V16.0.0), a list of up to sixty-four (64) TCI-States can be configured in a CORESET p. These TCI states are used to provide QCL relationships between the source DL RS(s) in one RS Set in the TCI State and the PDCCH DMRS ports (i.e., for DMRS ports for PDCCHs received in one of the search spaces defined over CORESET p). The source DL RS(s) can either be a CSI-RS or SSB.

[0025] For each CORESET, only one TCI state is activated by Medium Access Control (MAC) Control Element (CE) in NR Rel-16. The MAC CE specified for this can be found in Clause 6.1.3.15 of 3GPP TS 38.321 and is presented below:*****START EXCERPT FROM 3GPP TS 38.321*****6.1.3.15 TCI State Indication for UE-specific PDCCH MAC CE

[0026] The TCI State Indication for UE-specific PDCCH MAC CE is identified by a MAC subheader with LCID as specified in Table 6.2.1-1. It has a fixed size of 16 bits with following fields: Serving Cell ID: This field indicates the identity of the Serving Cell for which the MAC CE applies. The length of the field is 5 bits. If the indicated Serving Cell is configured as part of a simultaneousTCI-UpdateList-r16 or simultaneousTCI-UpdateListSecond-r16 as specified in TS 38.331 [5], this MAC CE applies to all the Serving Cells in the set simultaneousTCI-UpdateList-r16 or simultaneousTCI-UpdateListSecondr16, respectively; CORESET ID: This field indicates a Control Resource Set identified with ControlResourceSetId as specified in TS 38.331 [5], for which the TCI State is being indicated. In case the value of the field is 0, the field refers to the Control Resource Set configured by controlResourceSetZero as specified in TS 38.331 [5]. The length of the field is 4 bits; TCI State ID: This field indicates the TCI state identified by TCI-StateId as specified in TS 38.331 [5] applicable to the Control Resource Set identified by CORESET ID field. If the field of CORESET ID is set to 0, this field indicates a TCI-StateId for a TCI state of the first 64 TCI-states configured by tci-States-ToAddModList and tci-States-ToReleaseList in the PDSCH-Config in the active BWP. If the field of CORESET ID is set to the other value than 0, this field indicates a TCI-StateId configured by tci-StatesPDCCH-ToAddList and tci-StatePDCCH-ToReleaseList in the controlResourceSet identified by the indicated CORESET ID. The length of the field is 7 bits. [REPRODUCED HEREIN AS FIGURE 3] Figure 6.1.3.15-1: TCI State Indication for UE-specific PDCCH MAC CE *****END EXCERPT FROM 3GPP TS 38.321*****Ultra-Reliable Low Latency (URLLC) Data Transmission over Multiple Transmission Points

[0027] Reliable PDSCH transmission over multiple transmission points or panels or TRPS has been introduced in 3GPP for NR Rel-16, in which a TB may be transmitted over multiple TRPs to achieve diversity. Reliability is achieved by transmitting different layers of an encoded codeword (CW) for the TB on the same resource over two TRPs (Scheme 1a), or different parts of a CW on different frequency resources over two TRPs (Scheme 2a), or by repeating the same TB over two TRPs in time (Schemes 3 and 4) or frequency domain (Scheme 2b). For this purpose, two TCI states are indicated via the 'Transmission Configuration Indication' or TCI field in a DCI scheduling the PDSCH.

[0028] In NR Rel-17, it has been proposed to further introduce PDCCH enhancement with multiple TRPs by repeating a PDCCH from different TRPs as shown in Figure 4. One option is to associate PDCCH in a CORESET with multiple TCI states, and dividing REs of a PDCCH candidate into multiple subsets each associated with one of the TCI states. A PDCCH in each subset is then transmitted from a different TRP.

[0029] Document "Considerations on beam management for multi-TRP", ZTE, 3GPP draft R1-1906244 disclose an evaluation on how to enhance the default QCL assumption and BFR with multi-TRP / panel transmission. The following observations and proposals were made. Proposal 1: The default QCL assumption should be enhanced in the single PDCCH design considering in the case when the number of TCI states for CORESET is mismatched with the number of DMRS port groups of scheduling PDSCH or the number of TCI states for CORESET is larger than one. Proposal 2: Support configuration of two TCI states for one CORESET to support default QCL assumption for multi-TRP. Proposal 3: The QCL assumption of each PDSCH should be inferred from the lowest CORESET-ID within the CORESET group when the offset between the DL DCI and the PDSCH is less than the threshold. Proposal 4: For URLLC, allow multiple default QCL assumptions for multiple PDSCHs with repetition within one slot if the timing offset between DL DCI and those multiple PDSCHs is smaller than the threshold. Proposal 5. Whether two signals with different QCL-TypeD on one symbol can be received simultaneously is based on the CORESET groups associated with the two signals. Proposal 6: Support indication of simultaneous transmission capability from gNB for multi-TRP. Proposal 7: Two beam failure recovery procedures should be supported and each procedure is associated with one TRP. Proposal 8: Support CQI feedback based on the hypothesis of configured aggregation factor.

[0030] Document US 2019 / 0 373 450 A1 discloses methods, systems, and devices for wireless communications. A base station and a user equipment (UE) with a defined capability may communicate using beamformed wireless communications. The defined capability may be that the UE may support fewer activated physical downlink shared channel (PDSCH) transmission configuration indicator (TCI) states than activated control resource set (CORESET) TCI states. The defined capability UE and the base station may implement techniques to determine which TCI state to use when the UE supports fewer activated PDSCH TCI states than activated CORESET TCI states. The UE may use an activated PDSCH TCI state selected by a media access control (MAC) control element (CE), an activated TCI state of a specific CORESET, a TCI indicated in scheduling downlink control information, or an activated PDSCH TCI state selected by a radio resource control (RRC) message.

[0031] Document WO 2020 / 033549 A1 discloses a User equipment (UE) that includes processing circuitry coupled to memory. To configure the UE for multi-transmission reception point (TRP) reception, the processing circuitry is to decode radio resource control (RRC) signaling. The RRC signaling includes configuration information configuring a plurality of transmission configuration indication (TCI) states. A media access control (MAC) control element (CE) is decoded, where the MAC CE indicates multiple active TCI states of the configured plurality of TCI states. Multiple received beams are determined using the multiple active TCI states. Downlink information is decoded, where the downlink information originates from multiple TRPs and is received via the determined multiple receive beams associated with the multiple active TCI states.

[0032] Document WO 2019 / 244222 A1 discloses a user terminal comprising: a receiver that receives configuration information pertaining to a search space configuration; and a controller that determines, on the basis of the configuration information, the transmission configuration indicator (TCI) state for each application level or a physical downlink control channel (PDCCH) candidate included in a given control resource set (CORESET). The present disclosure thus enables a PDCCH to be appropriately monitored even when utilizing multiple transmission / reception points (TRPs).

[0033] Document CN 111 106 914 A disclose a method and device for determining quasi-co-location of a control resource set CORESET, a mobile terminal and a storage medium. The method comprises the steps: determining quasi-co-location QCL of the target control resource set CORESET according to the terminal capability and / or high-level configuration information. By utilizing the embodiment of the invention, the quasi-co-location QCL of the control resource set CORESET can be determined.

[0034] Document WO 2020 / 080916 A1 discloses a method for transmitting and receiving a plurality of PDSCHs in a wireless communication system and a device for same. In particular, the method carried out by a terminal comprises the steps of: receiving control information related to the transmission of a plurality of PDSCHs; receiving downlink control information (DCI) indicating a plurality of transmission configuration indicator (TCI) states; and receiving the plurality of PDSCHs, on the basis of the TCI states, in a plurality of time units related to the repeated reception of the plurality of PDSCHs, wherein the time units may be mapped to the TCI states cyclically or continuously.

[0035] Document "Consideration on TCI state MAC CE for mTRP mPDCCH transmissions", ZTE et al., 3GPP draft, R2-2001465, discloses an evaluation of MAC CE design for mPDCCH mTRP case. The following observation and proposals were made. Observation 1: Assuming that the current enhanced MAC CE is reused for the mPDCCH case, no matter the DCI for scheduling DL transmission or update of new TCI state for any TRP, the additional corporation between two nodes are needed. Proposal 1: In the case that mPDCCH mTRP transmission, the current R-15 TCI state activation / deactivation MAC CE can be reused for activating / deactivating TCI states for each TRP. Proposal 2: For the case the mPDCCH mTRP transmission, the reserved bit in R-15 TCI state activation / deactivation for UE specific PDSCH MAC CE shall be utilized to indicate the TRP transmission which shall apply this MAC CE.Summary

[0036] Systems and methods are disclosed herein for activation of two or more Transmission Configuration Indication (TCI) states for a Physical Downlink Control Channel (PDCCH) in one or more Control Resource Sets (CORESETs) in a cellular communications system.

[0037] According to the present disclosure, methods, a wireless communication device and a network node according to the independent claims are provided. Developments are set forth in the dependent claims.

[0038] According to a first aspect of the present disclosure, there is provided a method performed by a wireless communication device for activation of multiple Transmission Configuration Indication, TCI, states for a Physical Downlink Control Channel, PDCCH, in one or more Control Resource Sets, CORESETs, in a cellular communications system. The method comprises receiving, from a network node, a medium access control, MAC, control element, CE, signaling that activates two TCI states for one CORESET wherein the MAC CE signaling comprises: a first octet that comprises a serving cell identity, ID, of a serving cell of the wireless communication device (512) and a first part of a CORESET ID of the one CORESET; a second octet that comprises a second part of the CORESET ID of the one CORESET and a first TCI state ID of a first TCI state of the two TCI states that are activated for the one CORESET; and a third octet that comprises a second TCI state ID of a second TCI state of the two TCI states that are activated for the one CORESET.

[0039] According to a second aspect of the present disclosure, there is provided method performed by a network node for activation of multiple Transmission Configuration Indication, TCI, states for a Physical Downlink Control Channel, PDCCH, in one or more Control Resource Sets, CORESETs, in a cellular communications system. The method comprises sending, to a wireless communication device, a medium access control, MAC, control element, CE, signaling that activates two TCI states for one CORESET, wherein the MAC CE signaling comprises: a first octet that comprises a serving cell identity, ID, of a serving cell of the wireless communication device (512) and a first part of a CORESET ID of the one CORESET; a second octet that comprises a second part of the CORESET ID of the one CORESET and a first TCI state ID of a first TCI state of the two TCI states that are activated for the one CORESET; and a third octet that comprises a second TCI state ID of a second TCI state of the two TCI states that are activated for the one CORESET.

[0040] According to a third aspect of the present disclosure, there is provided a wireless communication device for activation of multiple Transmission Configuration Indication, TCI, states for a Physical Downlink Control Channel, PDCCH, in one or more Control Resource Sets, CORESETs, in a cellular communications system. The wireless communication device is adapted to perform the method of the first aspect.

[0041] According to a fourth aspect of the present disclosure, there is provided a network node for activation of multiple Transmission Configuration Indication, TCI, states for a Physical Downlink Control Channel, PDCCH, in one or more Control Resource Sets, CORESETs, in a cellular communications system. The network node is adapted to perform the method of the second aspect.

[0042] Whenever in the following disclosure any of the above-stated aspects (independent claims) is disclosed as "optional" (e.g. due to usage of conjunctive terms, such as "can", "may", "should" etc.), it is nevertheless to be read as "mandatory".Brief Description of the Drawings

[0043] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure. Hereinabove and in the following, "examples" pertain to principles underlying the claimed subject-matter and / or being useful for understanding the claimed subject-matter, while "embodiments" pertain to the claimed subject-matter within the claim scope. Figure 1 illustrates a typical slot in Third Generation Partnership Project (3GPP) New Radio (NR) according to an example; Figure 2 illustrates the basic NR time-frequency resource grid according to an example; Figure 3 is a reproduction of Figure 6.1.3.15-1 of 3GPP Technical Specification (TS) 38.321 according to an example; Figure 4 illustrates a Physical Downlink Control Channel (PDCCH) enhancement proposed in NR Release 17 with multiple Transmission / Reception Points (TRPs) where a PDCCH is repeated from different TRPs according to an example; Figure 5 illustrates a cellular communications system according to an example, in which embodiments of the present disclosure may be implemented; Figure 6 illustrates the operation of a base station and a User Equipment (UE) for activation of N TCI >1 TCI states for a Control Resource Set(s) (CORESET(s)) according to embodiments of the present disclosure; Figure 7 illustrates step 600 of Figure 6 in more detail for an embodiment according to the present disclosure; Figures 8 through 12 illustrate examples of a Medium Access Control (MAC) Control Element (CE) for activation of multiple TCI states for one or more CORESETs according to an embodiment of the present disclosure; Figure 13 illustrates step 600 of Figure 6 in more detail according to an embodiment of the present disclosure; Figure 14 is a schematic block diagram of a radio access node, or more generally a network node, according to an embodiment of the present disclosure, while Figures 15 and 16 are schematic block diagrams of a radio access node, or more generally a network node, according to an example; Figure 17 is a schematic block diagram of a wireless communication device (e.g., a UE) according to an embodiment of the present disclosure, while Figure 18 is a schematic block diagram of a wireless communication device (e.g., a UE) according to an example; Figure 19 illustrates a communication system according to an example, in which embodiments of the present disclosure may be implemented; Figure 20 illustrates the host computer, base station, and UE of Figure 19 according to an example; and Figures 21, 22, 23, and 24 are flow charts that illustrate methods implemented in a communication system such as that of Figure 19 according to an example.

[0044] Whenever in the following disclosure the term "embodiment" occurs, reference is to be made to the figure description above to clarify whether an embodiment or an example is meant.Detailed Description

[0045] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features, and advantages of the enclosed embodiments will be apparent from the following description.

[0046] Radio Node: As used herein, a "radio node" is either a radio access node or a wireless communication device.

[0047] Radio Access Node: As used herein, a "radio access node" or "radio network node" or "radio access network node" is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and / or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station (e.g., a network node that implements a gNB Central Unit (gNB-CU) or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node.

[0048] Core Network Node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

[0049] Communication Device: As used herein, a "communication device" is any type of device that has access to an access network. Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC). The communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and / or data via a wireless or wireline connection.

[0050] Wireless Communication Device: One type of communication device is a wireless communication device, which may be any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of a wireless communication device include, but are not limited to: a User Equipment device (UE) in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (IoT) device. Such wireless communication devices may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC. The wireless communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and / or data via a wireless connection.

[0051] Network Node: As used herein, a "network node" is any node that is either part of the RAN or the core network of a cellular communications network / system.

[0052] Transmission / Reception Point (TRP): In some embodiments, a TRP may be either a network node, a radio head, a spatial relation, or a Transmission Configuration Indicator (TCI) state. A TRP may be represented by a spatial relation or a TCI state in some embodiments. In some embodiments, a TRP may be using multiple TCI states. In some embodiments, a TRP may be a part of the gNB transmitting and receiving radio signals to / from UE according to physical layer properties and parameters inherent to that element. In some embodiments, in Multiple TRP (multi-TRP) operation, a serving cell can schedule UE from two TRPs, providing better coverage, reliability and / or data rates for PDSCH and / or PDCCH. There are two different operation modes for scheduling PDSCH over multi-TRP: single Downlink Control Information (DCI) and multi-DCI. For both modes, control of uplink and downlink operation is done by both physical layer and Medium Access Control (MAC). In single-DCI mode, UE is scheduled by the same DCI for both TRPs and in multi-DCI mode, UE is scheduled by independent DCIs from each TRP.

[0053] In some embodiments, a set Transmission Points (TPs) is a set of geographically co-located transmit antennas (e.g., an antenna array (with one or more antenna elements)) for one cell, part of one cell or one Positioning Reference Signal (PRS) -only TP. TPs can include base station (eNB) antennas, Remote Radio Heads (RRHs), a remote antenna of a base station, an antenna of a PRS-only TP, etc. One cell can be formed by one or multiple TPs. For a homogeneous deployment, each TP may correspond to one cell.

[0054] In some embodiments, a set of TRPs is a set of geographically co-located antennas (e.g., an antenna array (with one or more antenna elements)) supporting TP and / or Reception Point (RP) functionality.

[0055] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

[0056] Note that, in the description herein, reference may be made to the term "cell"; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

[0057] There currently exist certain challenge(s). There is no mechanism in NR to activate multiple Transmission Configuration Indicator (TCI) states for Physical Downlink Control Channel (PDCCH) in a Control Resource Set (CORESET). Currently, for each CORESET in NR, only one TCI state can be activated. The activation is typically done with a Medium Access Control (MAC) Control Element (CE). Thus, there is a need for systems and methods for activating multiple TCI states for a CORESET and the associated signaling details.

[0058] Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. In this disclosure, different ways of signaling the activation of N TCI >1 TCI states for a CORESET(s) are disclosed. In one embodiment, the activation of N TCI >1 TCI states for a CORESET(s) is signaled in a way that reuses the existing MAC CE. Embodiments are also disclosed herein for signaling the activation of N TCI >1 TCI states for a CORESET(s) in a new way, e.g., using a new MAC CE.

[0059] Certain embodiments may provide one or more of the following technical advantage(s). Advantages of the solution depend on the particular embodiment. One advantage of the first embodiment, which proposes a way to reuse the existing MAC CE, is that no new MAC CE needs to be specified. In NR, many new MAC CEs have been defined to the extent that the Logical Channel Identity (LCID) space is running out. Even with a solution to the issue of the limited LCID space, adding more MAC CEs especially for similar functionality complicates the NR specification and interoperability between releases. In this embodiment, a number of lists may be needed. For example, assuming that a total of 64 TCI states are possible and that 2 TCI states are selected per the new list being introduced, then there are 2016 different ways of choosing 2 TCI states out of 64 possible TCI states. But since the TCI state identity (ID) field in the MAC CE only has 7 bits, there is a maximum of 128 lists.

[0060] One advantage of the second embodiment is that it enables more flexible activated TCI state selection than the first embodiment. In the first embodiment, the pair of TCI states is preconfigured (e.g., by Radio Resource Control (RRC) signaling), and enabling the same flexibility as in the second embodiment may not be possible due to the amount of permutations. Another advantage of the second embodiment as it relates to TCI state activation for two or more CORESETs using a single MAC CE is that it saves overhead compared to existing MAC CE signaling for CORESET TCI state activation. In the existing MAC CE for TCI state activation for a CORESET, one MAC CE needs to be sent for each CORESET. The solution proposed in the second embodiment enables a flexible number of TCI states (i.e., two or more TCI states) to be activated for multiple CORESETs, which saves signaling overhead.

[0061] Figure 5 illustrates one example of a cellular communications system 500 in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system 500 is a 5G system (5GS) including a Next Generation RAN (NG-RAN) and a 5G Core (5GC). In this example, the RAN includes radio access nodes 502-1 and 502-2, which in the 5GS include NR base stations (gNBs) and optionally next generation eNBs (ng-eNBs) (e.g., LTE RAN nodes connected to the 5GC), controlling corresponding (macro) cells 504-1 and 504-2. The base stations 502-1 and 502-2 are generally referred to herein collectively as base stations 502 and individually as base station 502. Likewise, the (macro) cells 504-1 and 504-2 are generally referred to herein collectively as (macro) cells 504 and individually as (macro) cell 504. Each base station 502 includes one or more Transmission Points (TRPs) (not shown). Also, in case of multi-TRP transmission, one of the TRPs may be another base station, e.g., data are transmitted from two base stations to a wireless communication device 512 (under control of one of the base stations through base station coordination).

[0062] The RAN may also include a number of low power nodes 506-1 through 506-4 controlling corresponding small cells 508-1 through 508-4. The low power nodes 506-1 through 506-4 can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells 508-1 through 508-4 may alternatively be provided by the base stations 502. The low power nodes 506-1 through 506-4 are generally referred to herein collectively as low power nodes 506 and individually as low power node 506. Likewise, the small cells 508-1 through 508-4 are generally referred to herein collectively as small cells 508 and individually as small cell 508. Each of the low power nodes 506 is or includes one (or more) TRP. Also, in case of multi-TRP transmission, one of the TRPs may be another low power node 506 (or a base station 502).

[0063] The cellular communications system 500 also includes a core network 510, which in the 5GS is the 5GC. The base stations 502 (and optionally the low power nodes 506) are connected to the core network 510.

[0064] The base stations 502 and the low power nodes 506 provide service to wireless communication devices 512-1 through 512-5 in the corresponding cells 504 and 508. The wireless communication devices 512-1 through 512-5 are generally referred to herein collectively as wireless communication devices 512 and individually as wireless communication device 512. In the following description, the wireless communication devices 512 are oftentimes UEs and as such sometimes referred to herein as UEs 512, but the present disclosure is not limited thereto.

[0065] Figure 6 illustrates the operation of a base station 502 and a UE 512 for activation of N TCI >1 TCI states for a CORESET(s) in accordance with embodiments of the present disclosure. Optional steps are represented by dashed lines / boxes. As illustrated, the base station 502 signals activation of N TCI >1 TCI states for a CORESET(s) to the UE 512 (step 600). As discussed below, in some embodiments, the base station 502 signals activation of N TCI >1 TCI states for a single CORESET. In some other embodiments, the base station 502 signals activation of N TCI >1 TCI states for each of two (or more) CORESETs, where N TCI may be the same for all of these CORESETs or may be different for at least two of these CORESETs. As described below, some embodiments, the signaling of the activation of the N TCI >1 TCI states for the CORESET(s) uses an existing MAC CE (e.g., an existing PDCCH MAC CE). However, in some other embodiments, the signaling of the activation of the N TCI >1 TCI states for the CORESET(s) uses a new signaling structure such as, e.g., a new MAC CE (e.g., a new PDCCH MAC CE).

[0066] The UE 512 then receives PDCCHs (e.g., from two or more TRPs) in the CORESET(s) in accordance with the activated TCI states (step 602). For example, a particular PDCCH may be repeated from two or more TRPs (e.g., as shown in Figure 4 described above). In one particular example, PDCCH in a CORESET is associated with multiple activated TCI states, and Resource Elements (REs) of a PDCCH candidate are divided into multiple subsets each associated with one of the activated TCI states. A PDCCH in each subset is then transmitted from a different TRP and received by the UE 512 in accordance with the respective (activated) TCI states.

[0067] The UE may then perform one or more actions based on the received PDCCHs (step 604). For example, if the received PDCCHs are repetitions of a same PDCCH, then that same PDCCH is decoded to obtain the respective DCI, and the UE 512 then operates in accordance with the DCI (e.g., receives a downlink transmission in accordance with a downlink assignment in the DCI or transmits an uplink transmission in accordance with an uplink grant in the DCI).

[0068] Now, details of embodiments of the signaling of the activation of the N TCI >1 TCI states for the CORESET(s), e.g., in step 600 of Figure 6 are provided.First Embodiment - Reuse of Existing MAC CE

[0069] In this embodiment, for each CORESET (i.e., ControlResourceSet), the UE 512 is configured (e.g., via RRC signaling) with multiple TCI state lists, each having up to a maximum number (e.g., predefined or preconfigured maximum number) of TCI states in each list. In some embodiments, the maximum number of TCI states in each list is given by a parameter (e.g., an RRC parameter referred to herein as maxNrofTCI-StatesPerPDCCH, which is set to an integer value (e.g., two). The TCI states in each of the multiple TCI state lists are the activated TCI states for the CORESET if the list is selected. The existing MAC CE (see Figure 3) is reused to activate one of the lists by interpreting the "TCI state ID" field as an ID (e.g., tciListID in the example below) of the list of TCI states to be activated.

[0070] Figure 7 illustrates step 600 of Figure 6 in more detail for the first embodiment. As illustrated, in regarding to the signaling of step 600, the base station 502 configures (e.g., via RRC signaling) the UE 512 with two or more TCI state lists, each having up to the maximum number of TCI states (step 700). The base station 502 transmits a MAC CE (e.g., a PDCCH MAC CE) to the UE 512, where the MAC CE includes an ID of one of the two or more TCI state lists to be activated (step 702). In the first embodiment, the MAC CE uses the existing MAC CE format (see Fig. 3), where the "TCI state ID" field is interpreted as the ID (e.g., tciListID in the example below) of the list of TCI states to be activated.

[0071] In one example implementation, the first embodiment may be implemented by the following additions to 3GPP TS 38.311 and 3GPP TS 38 321. The parts emphasized with bolded and underlined text are new additions. ControlResourceSet field descriptions cce-REG-MappingType Mapping of Control Channel Elements (CCE) to Resource Element Groups (REG) (see TS 38.211

[16] , clauses 7.3.2.2 and 7.4.1.3.2).controlResourceSetId Identifies the instance of the ControlResourceSetIE. Value 0 identifies the common CORESET configured in MIB and in ServingCellConfigCommon (controlResourceSetZero) and is hence not used here in the ControlResourceSet IE. Other values identify CORESETs configured by dedicated signalling or in SIB1.The controlResourceSetId is unique among the BWPs of a serving cell.If the field controlResourceSetId-r16 is present, the UE shall ignore the controlResourceSetId field (without suffix).coresetPoolIndex The index of the CORESET pool for this CORESET as specified in TS 38.213

[13] (clauses 9 and 10) and TS 38.214

[19] (clauses 5.1 and 6.1). If the field is absent, the UE applies the value 0.duration Contiguous time duration of the CORESET in number of symbols (see TS 38.211

[16] , clause 7.3.2.2).frequencyDomainResources Frequency domain resources for the CORESET. Each bit corresponds a group of 6 RBs, with grouping starting from the first RB group (see TS 38.213

[13] , clause 10.1) in the BWP. The first (left-most / most significant) bit corresponds to the first RB group in the BWP, and so on. A bit that is set to 1 indicates that this RB group belongs to the frequency domain resource of this CORESET. Bits corresponding to a group of RBs not fully contained in the bandwidth part within which the CORESET is configured are set to zero (see TS 38.211

[16] , clause 7.3.2.2).interleaverSize Interleaver-size (see TS 38.211

[16] , clause 7.3.2.2).pdcch-DMRS-ScramblingID PDCCH DMRS scrambling initialization (see TS 38.211

[16] , clause 7.4.1.3.1).When the field is absent the UE applies the value of the physCellId configured for this serving cell.precoderGranularity Precoder granularity in frequency domain (see TS 38.211

[16] , clauses 7.3.2.2 and 7.4.1.3.2).rb-Offset Indicates the RB level offset in units of RB from the first RB of the first 6RB group to the first RB of BWP (see 38.213

[13] , clause 10.1). When the field is absent, the UE applies the value 0.reg-BundleSize Resource Element Groups (REGs) can be bundled to create REG bundles. This parameter defines the size of such bundles (see TS 38.211

[16] , clause 7.3.2.2).shiftIndex When the field is absent the UE applies the value of the physCellId configured for this serving cell (see TS 38.211

[16] , clause 7.3.2.2).tci-PresentInDCI This field indicates if TCI field is present or absent in DCI format 1_1. When the field is absent the UE considers the TCI to be absent / disabled. In case of cross carrier scheduling, the network sets this field to enabled for the ControlResourceSet used for cross carrier scheduling in the scheduling cell (see TS 38.214

[19] , clause 5.1.5).tci-PresentInDCI-ForDCI-Format1-2 Configures the number of bits for "Transmission configuration indicator" in DCI format 1_2. When the field is absent the UE applies the value of 0 bit for the "Transmission configuration indicator" in DCI format 1_2 (see TS 38.212, clause 7.3.1 and TS 38.214, clause 5.1.5).tci-StatesPDCCH-ToAddList A subset of the TCI states defined in pdsch-Config included in the BWP-DownlinkDedicated corresponding to the serving cell and to the DL BWP to which the ControlResourceSet belong to. They are used for providing QCL relationships between the DL RS(s) in one RS Set (TCI-State) and the PDCCH DMRS ports (see TS 38.213

[13] , clause 6.). The network configures at most maxNrofTCI-StatesPDCCH entries.tci-StatesListPDCCH A list of TCI states that are a subset of the TCI states defined in pdsch-Config included in the BWP-DownlinkDedicated corresponding to the serving cell and to the DL BWP to which the ControlResourceSet belong to. They are used for providing QCL relationships between the DL RS(s) in one RS Set (TCI-State) and the PDCCH DMRS ports (see TS 38.213

[13] , clause 6.). The network configures at most maxNrofTCI-StatesPDCCH entries. UE ignores tci-StatesPDCCH-ToAddList if tci-StatesListPDCCH is configured

[0072] The TCI State Indication for UE-specific PDCCH MAC CE is identified by a MAC subheader with LCID as specified in Table 6.2.1-1. It has a fixed size of 16 bits with following fields: Serving Cell ID: This field indicates the identity of the Serving Cell for which the MAC CE applies. The length of the field is 5 bits. If the indicated Serving Cell is configured as part of a simultaneousTCI-UpdateList-r16 or simultaneousTCI-UpdateListSecond-r16 as specified in TS 38.331 [5], this MAC CE applies to all the Serving Cells in the set simultaneousTCI-UpdateList-r16 or simultaneousTCI-UpdateListSecond-r16, respectively; CORESET ID: This field indicates a Control Resource Set identified with ControlResourceSetId as specified in TS 38.331 [5], for which the TCI State is being indicated. In case the value of the field is 0, the field refers to the Control Resource Set configured by controlResourceSetZero as specified in TS 38.331 [5]. The length of the field is 4 bits; TCI State ID: This field indicates the TCI state identified by TCI-StateId or tciListID as specified in TS 38.331 [5] applicable to the Control Resource Set identified by CORESET ID field. If the field of CORESET ID is set to 0, this field indicates a TCI-StateId for a TCI state of the first 64 TCI-states configured by tci-States-ToAddModList and tci-States-ToReleaseList in the PDSCH-Config in the active BWP. If the field of CORESET ID is set to the other value than 0 and UE is not configured with tci-StatesListPDCCH, this field indicates a TCI-StateId configured by tci-StatePDCCH-ToAddList and tci-StatesPDCCH-ToReleaseList in the controlResourceSet identified by the indicated CORESET ID. If the field of CORESET ID is set to the other value than 0 and UE is configured with tci-StatesListPDCCH, this field indicates a tciListID configured by tci-StatesListPDCCH in the controlResourceSet identified by the indicated CORESET ID. The length of the field is 7 bits. [REPRODUCED HEREIN AS FIGURE 3] Figure 6.1.3.15-1: TCI State Indication for UE-specific PDCCH MAC CE *****END CHANGES TO 3GPP TS 38.311 AND TS 38.321*****Second Embodiment - New MAC CE Options

[0073] In one embodiment, a new MAC CE is introduced to activate up to two TCI states to one CORESET ID as shown in Figure 8. A "C" field is used to indicate which TCI state should be assumed by the UE 512 as default TCI state for PDSCH. If C=1 (or C=0), the default TCI state is the one in Octet 2; and, if C=0 (or C=1), the default TCI state is the one in Octet 3 which is the same octet where the C field is.

[0074] What is meant by default TCI state for PDSCH to be assumed by the UE 512 in this embodiment (and also in following embodiments) is the following. When the UE 512 assumes that the Demodulation Reference Signal (DMRS) ports of PDSCH of a serving cell are quasi co-located with the reference signal(s) (RS(s)) with respect to the QCL parameter(s) used for PDCCH quasi co-location indication in a CORESET, the default TCI state for PDSCH is the TCI state activated for PDCCH in the CORESET. For example, in NR Release 16 if none of the TCI codepoints in DCI for PDSCH scheduling are mapped to more than a single TCI state activated for PDSCH and the offset between the reception of a DL DCI and the corresponding PDSCH is less than a threshold timeDurationForQCL configured by higher layers, the UE may assume the default TCI state for receiving the PDSCH. The default TCI state in this case is the activated TCI state of the CORESET with the lowest CORESET-ID in the latest slot in which one or more CORESETs are monitored by the UE. In other word, the DMRS ports of the PDSCH are quasi co-located with RS(s) with respect to the QCL parameter(s) of the default TCI state in this case.

[0075] If the new MAC CE of the second embodiment is defined as fixed size MAC CE, by default the header does not include a length field. In this case, the MAC CE always activates two TCI states per CORESET. If this MAC CE is defined as flexible size MAC CE, the header will include a length field, and UE can interpret whether the MAC CE has one or two TCI states (two or three octets in the main body of the MAC CE) based on the length field.

[0076] In another embodiment, more than two TCI states can be mapped to one CORESET ID as shown in Figure 9. In the example of Figure 9, three TCI states are activated for one CORESET (i.e., the CORESET that corresponds to the given CORESET ID). One difference between this embodiment and that of Figure 8 is that two or more bits are needed for the C field. The C field with 2 or more bits in this embodiment chooses which TCI states among the TCI states activated within the MAC CE should be used by the UE 512 as default TCI state for PDSCH.

[0077] In a further embodiment, the new MAC CE is as shown in Figure 10, where up to N TCI states may be activated. If C k =1, then TCI state ID k is the default TCI state for PDSCH. Only one C k can be set to 1. If C k =0 for k=1,..., N-1, then TCI state ID 0 is the default TCI state for PDSCH.

[0078] If this MAC CE is defined as fixed size MAC CE, by default the header does not include a length field. In this case, the MAC CE always activates two TCI states per CORESET. If this MAC CE is defined as flexible size MAC CE, the header will include a length field and UE can interpret whether the MAC CE has two TCI states or N TCI states (two or N octets in the main body of the MAC CE) based on the length field.

[0079] In some embodiments, only the first TCI state ID provided in the MAC CE is used as default TCI state for PDSCH. This means TCI state ID 0 (7 bits) in Figure 8, Figure 9, and Figure 10 is used as default TCI state of PDSCH. The additional TCI states activated for a CORESET in the examples of Figure 8, Figure 9, and Figure 10 are only used for the purpose of subsets of REs of a PDCCH candidate. In this embodiment, the 'C' field(s) are no longer needed as the default TCI state for PDSCH is already predefined by the first activated TCI state with TCI state ID 0 . Hence, in this embodiment, the 'C' field(s) are replaced by reserved 'R' fields in Figure 8, Figure 9, and Figure 10.

[0080] In some embodiments, the new MAC CE that provides more than one active TCI state per CORESET is only applicable to CORESETs other than CORESET 0 (i.e., a CORESET whose CORESET ID is set to a value other than 0).

[0081] In another embodiment, the number of CORESETs per serving cell is increased to larger than 16 (e.g., 20) which requires an additional bit to be included in the CORESET ID field. As shown in Figure 11, CORESET ID is given by a 5-bit field where 3 bits are given in octet OCT1 and the remaining 2 bits are given in OCT2. For indicating the first activated TCI state for the CORESET, 6 out of 7 bits of TCI state ID 0 are provided in octet OCT2 and the remaining 1 bit of TCI state ID 0 is provided in octet OCT3. For indicating the second activated TCI state for the CORESET, the 7-bit TCI state ID 1 is provided in octet OCT3.

[0082] The above embodiments can be extended to the case where TCI state activation for more than one CORESET may be included in one MAC CE where one or two TCI states can be activated for each MAC CE. In this regard, Figure 12 shows an example where TCI state activation for two CORESETs within the same serving cell are provided in the same MAC CE. Further details of this MAC CE design are given below: The field CORESET ID r represents the CORESET ID of the r th< CORESET for which TCI state(s) activation is provided in the MAC CE. The field TCI state ID r,i represents the i th< activated TCI state for the CORESET associated with CORESET ID r . The field G r is an indicator that indicates if TCI state activation for an additional CORESET (i.e., CORESET corresponding to CORESET ID r+1 ) will be provided in the new MAC CE.

[0083] Note that, in one embodiment, in the above embodiments involving the introduction of a new MAC CE, each of the fields TCI state ID 0 , TCI state ID 1 , ... indicate a TCI-StateId configured by tci-StatesPDCCH-ToAddList and tci-StatesPDCCH- ToReleaseList in the controlResourceSet identified by the indicated CORESET ID.

[0084] Figure 13 illustrates step 600 of Figure 6 in more detail for the second embodiment. As illustrated, in regard to the signaling of step 600, the base station 502 may also configure (e.g., via RRC signaling) the UE 512 with a TCI state list having up to the maximum number of TCI states for each CORESET (step 1300). The base station 502 transmits a MAC CE (e.g., a PDCCH MAC CE) to the UE 512, where the MAC CE includes information that indicates the activated TCI states and, in some embodiments, the CORESET(s) for which the indicated TCI states are activated (step 1302). For example, the MAC CE may be the MAC CE of any one of Figures 8 to 12 described above. Note that the TCI state IDs included in the MAC CE may be indices of the TCI states in the TCI state list of the respective CORESET configured in step 1300.Additional Details

[0085] Figure 14 is a schematic block diagram of a radio access node 1400 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The radio access node 1400 may be, for example, a base station 502, a low power node 506, a TRP (e.g., a TRP of a base station 502), or the like. As illustrated, the radio access node 1400 includes a control system 1402 that includes one or more processors 1404 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and / or the like), memory 1406, and a network interface 1408. The one or more processors 1404 are also referred to herein as processing circuitry. In addition, the radio access node 1400 may include one or more radio units 1410 that each includes one or more transmitters 1412 and one or more receivers 1414 coupled to one or more antennas 1416. The radio units 1410 may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) 1410 is external to the control system 1402 and connected to the control system 1402 via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s) 1410 and potentially the antenna(s) 1416 are integrated together with the control system 1402. The one or more processors 1404 operate to provide one or more functions of the radio access node 1400 as described herein (e.g., one or more functions of a base station 502, gNB, or TRP as described herein). In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory 1406 and executed by the one or more processors 1404.

[0086] Figure 15 is a schematic block diagram that illustrates a virtualized embodiment of the radio access node 1400 according to some embodiments of the present disclosure. This discussion is equally applicable to other types of network nodes. Further, other types of network nodes may have similar virtualized architectures. Again, optional features are represented by dashed boxes.

[0087] As used herein, a "virtualized" radio access node is an implementation of the radio access node 1400 in which at least a portion of the functionality of the radio access node 1400 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the radio access node 1400 may include the control system 1402 and / or the one or more radio units 1410, as described above. The control system 1402 may be connected to the radio unit(s) 1410 via, for example, an optical cable or the like. The radio access node 1400 includes one or more processing nodes 1500 coupled to or included as part of a network(s) 1502. If present, the control system 1402 or the radio unit(s) are connected to the processing node(s) 1500 via the network 1502. Each processing node 1500 includes one or more processors 1504 (e.g., CPUs, ASICs, FPGAs, and / or the like), memory 1506, and a network interface 1508.

[0088] In this example, functions 1510 of the radio access node 1400 described herein (e.g., one or more functions of a base station 502, gNB, or TRP as described herein) are implemented at the one or more processing nodes 1500 or distributed across the one or more processing nodes 1500 and the control system 1402 and / or the radio unit(s) 1410 in any desired manner. In some particular embodiments, some or all of the functions 1510 of the radio access node 1400 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 1500. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 1500 and the control system 1402 is used in order to carry out at least some of the desired functions 1510. Notably, in some embodiments, the control system 1402 may not be included, in which case the radio unit(s) 1410 communicate directly with the processing node(s) 1500 via an appropriate network interface(s).

[0089] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the radio access node 1400 or a node (e.g., a processing node 1500) implementing one or more of the functions 1510 of the radio access node 1400 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0090] Figure 16 is a schematic block diagram of the radio access node 1400 according to some other embodiments of the present disclosure. The radio access node 1400 includes one or more modules 1600, each of which is implemented in software. The module(s) 1600 provide the functionality of the radio access node 1400 described herein (e.g., one or more functions of a base station 502, gNB, or TRP as described herein). This discussion is equally applicable to the processing node 1500 of Figure 15 where the modules 1600 may be implemented at one of the processing nodes 1500 or distributed across multiple processing nodes 1500 and / or distributed across the processing node(s) 1500 and the control system 1402.

[0091] Figure 17 is a schematic block diagram of a wireless communication device 1700 according to some embodiments of the present disclosure. The wireless communication device 1700 may be, for example, the wireless communication device or UE 512 as described herein. As illustrated, the wireless communication device 1700 includes one or more processors 1702 (e.g., CPUs, ASICs, FPGAs, and / or the like), memory 1704, and one or more transceivers 1706 each including one or more transmitters 1708 and one or more receivers 1710 coupled to one or more antennas 1712. The transceiver(s) 1706 includes radio-front end circuitry connected to the antenna(s) 1712 that is configured to condition signals communicated between the antenna(s) 1712 and the processor(s) 1702, as will be appreciated by on of ordinary skill in the art. The processors 1702 are also referred to herein as processing circuitry. The transceivers 1706 are also referred to herein as radio circuitry. In some embodiments, the functionality of the wireless communication device 1700 described above (e.g., one or more functions of the wireless communication device 512 or UE 512 described above) may be fully or partially implemented in software that is, e.g., stored in the memory 1704 and executed by the processor(s) 1702. Note that the wireless communication device 1700 may include additional components not illustrated in Figure 17 such as, e.g., one or more user interface components (e.g., an input / output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and / or the like and / or any other components for allowing input of information into the wireless communication device 1700 and / or allowing output of information from the wireless communication device 1700), a power supply (e.g., a battery and associated power circuitry), etc.

[0092] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the wireless communication device 1700 according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0093] Figure 18 is a schematic block diagram of the wireless communication device 1700 according to some other embodiments of the present disclosure. The wireless communication device 1700 includes one or more modules 1800, each of which is implemented in software. The module(s) 1800 provide the functionality of the wireless communication device 1700 described herein (e.g., one or more functions of the wireless communication device 512 or UE 512 described above).

[0094] With reference to Figure 19, in accordance with an embodiment, a communication system includes a telecommunication network 1900, such as a 3GPP-type cellular network, which comprises an access network 1902, such as a RAN, and a core network 1904. The access network 1902 comprises a plurality of base stations 1906A, 1906B, 1906C, such as Node Bs, eNBs, gNBs, or other types of wireless Access Points (APs), each defining a corresponding coverage area 1908A, 1908B, 1908C. Each base station 1906A, 1906B, 1906C is connectable to the core network 1904 over a wired or wireless connection 1910. A first UE 1912 located in coverage area 1908C is configured to wirelessly connect to, or be paged by, the corresponding base station 1906C. A second UE 1914 in coverage area 1908A is wirelessly connectable to the corresponding base station 1906A. While a plurality of UEs 1912, 1914 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 1906.

[0095] The telecommunication network 1900 is itself connected to a host computer 1916, which may be embodied in the hardware and / or software of a standalone server, a cloud-implemented server, a distributed server, or as processing resources in a server farm. The host computer 1916 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. Connections 1918 and 1920 between the telecommunication network 1900 and the host computer 1916 may extend directly from the core network 1904 to the host computer 1916 or may go via an optional intermediate network 1922. The intermediate network 1922 may be one of, or a combination of more than one of, a public, private, or hosted network; the intermediate network 1922, if any, may be a backbone network or the Internet; in particular, the intermediate network 1922 may comprise two or more sub-networks (not shown).

[0096] The communication system of Figure 19 as a whole enables connectivity between the connected UEs 1912, 1914 and the host computer 1916. The connectivity may be described as an Over-the-Top (OTT) connection 1924. The host computer 1916 and the connected UEs 1912, 1914 are configured to communicate data and / or signaling via the OTT connection 1924, using the access network 1902, the core network 1904, any intermediate network 1922, and possible further infrastructure (not shown) as intermediaries. The OTT connection 1924 may be transparent in the sense that the participating communication devices through which the OTT connection 1924 passes are unaware of routing of uplink and downlink communications. For example, the base station 1906 may not or need not be informed about the past routing of an incoming downlink communication with data originating from the host computer 1916 to be forwarded (e.g., handed over) to a connected UE 1912. Similarly, the base station 1906 need not be aware of the future routing of an outgoing uplink communication originating from the UE 1912 towards the host computer 1916.

[0097] Example implementations, in accordance with an embodiment, of the UE, base station, and host computer discussed in the preceding paragraphs will now be described with reference to Figure 20. In a communication system 2000, a host computer 2002 comprises hardware 2004 including a communication interface 2006 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 2000. The host computer 2002 further comprises processing circuitry 2008, which may have storage and / or processing capabilities. In particular, the processing circuitry 2008 may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The host computer 2002 further comprises software 2010, which is stored in or accessible by the host computer 2002 and executable by the processing circuitry 2008. The software 2010 includes a host application 2012. The host application 2012 may be operable to provide a service to a remote user, such as a UE 2014 connecting via an OTT connection 2016 terminating at the UE 2014 and the host computer 2002. In providing the service to the remote user, the host application 2012 may provide user data which is transmitted using the OTT connection 2016.

[0098] The communication system 2000 further includes a base station 2018 provided in a telecommunication system and comprising hardware 2020 enabling it to communicate with the host computer 2002 and with the UE 2014. The hardware 2020 may include a communication interface 2022 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 2000, as well as a radio interface 2024 for setting up and maintaining at least a wireless connection 2026 with the UE 2014 located in a coverage area (not shown in Figure 20) served by the base station 2018. The communication interface 2022 may be configured to facilitate a connection 2028 to the host computer 2002. The connection 2028 may be direct or it may pass through a core network (not shown in Figure 20) of the telecommunication system and / or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, the hardware 2020 of the base station 2018 further includes processing circuitry 2030, which may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The base station 2018 further has software 2032 stored internally or accessible via an external connection.

[0099] The communication system 2000 further includes the UE 2014 already referred to. The UE's 2014 hardware 2034 may include a radio interface 2036 configured to set up and maintain a wireless connection 2026 with a base station serving a coverage area in which the UE 2014 is currently located. The hardware 2034 of the UE 2014 further includes processing circuitry 2038, which may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The UE 2014 further comprises software 2040, which is stored in or accessible by the UE 2014 and executable by the processing circuitry 2038. The software 2040 includes a client application 2042. The client application 2042 may be operable to provide a service to a human or non-human user via the UE 2014, with the support of the host computer 2002. In the host computer 2002, the executing host application 2012 may communicate with the executing client application 2042 via the OTT connection 2016 terminating at the UE 2014 and the host computer 2002. In providing the service to the user, the client application 2042 may receive request data from the host application 2012 and provide user data in response to the request data. The OTT connection 2016 may transfer both the request data and the user data. The client application 2042 may interact with the user to generate the user data that it provides.

[0100] It is noted that the host computer 2002, the base station 2018, and the UE 2014 illustrated in Figure 20 may be similar or identical to the host computer 1916, one of the base stations 1906A, 1906B, 1906C, and one of the UEs 1912, 1914 of Figure 19, respectively. This is to say, the inner workings of these entities may be as shown in Figure 20 and independently, the surrounding network topology may be that of Figure 19.

[0101] In Figure 20, the OTT connection 2016 has been drawn abstractly to illustrate the communication between the host computer 2002 and the UE 2014 via the base station 2018 without explicit reference to any intermediary devices and the precise routing of messages via these devices. The network infrastructure may determine the routing, which may be configured to hide from the UE 2014 or from the service provider operating the host computer 2002, or both. While the OTT connection 2016 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

[0102] The wireless connection 2026 between the UE 2014 and the base station 2018 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE 2014 using the OTT connection 2016, in which the wireless connection 2026 forms the last segment. More precisely, the teachings of these embodiments may improve, e.g., reliability and thereby provide benefits such as, e.g., improved performance.

[0103] A measurement procedure may be provided for the purpose of monitoring data rate, latency, and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 2016 between the host computer 2002 and the UE 2014, in response to variations in the measurement results. The measurement procedure and / or the network functionality for reconfiguring the OTT connection 2016 may be implemented in the software 2010 and the hardware 2004 of the host computer 2002 or in the software 2040 and the hardware 2034 of the UE 2014, or both. In some embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 2016 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which the software 2010, 2040 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 2016 may include message format, retransmission settings, preferred routing, etc.; the reconfiguring need not affect the base station 2018, and it may be unknown or imperceptible to the base station 2018. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating the host computer 2002's measurements of throughput, propagation times, latency, and the like. The measurements may be implemented in that the software 2010 and 2040 causes messages to be transmitted, in particular empty or 'dummy' messages, using the OTT connection 2016 while it monitors propagation times, errors, etc.

[0104] Figure 21 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 19 and 20. For simplicity of the present disclosure, only drawing references to Figure 21 will be included in this section. In step 2100, the host computer provides user data. In sub-step 2102 (which may be optional) of step 2100, the host computer provides the user data by executing a host application. In step 2104, the host computer initiates a transmission carrying the user data to the UE. In step 2106 (which may be optional), the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 2108 (which may also be optional), the UE executes a client application associated with the host application executed by the host computer.

[0105] Figure 22 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 19 and 20. For simplicity of the present disclosure, only drawing references to Figure 22 will be included in this section. In step 2200 of the method, the host computer provides user data. In an optional sub-step (not shown) the host computer provides the user data by executing a host application. In step 2202, the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In step 2204 (which may be optional), the UE receives the user data carried in the transmission.

[0106] Figure 23 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 19 and 20. For simplicity of the present disclosure, only drawing references to Figure 23 will be included in this section. In step 2300 (which may be optional), the UE receives input data provided by the host computer. Additionally or alternatively, in step 2302, the UE provides user data. In sub-step 2304 (which may be optional) of step 2300, the UE provides the user data by executing a client application. In sub-step 2306 (which may be optional) of step 2302, the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer. In providing the user data, the executed client application may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the UE initiates, in sub-step 2308 (which may be optional), transmission of the user data to the host computer. In step 2310 of the method, the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.

[0107] Figure 24 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 19 and 20. For simplicity of the present disclosure, only drawing references to Figure 24 will be included in this section. In step 2400 (which may be optional), in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In step 2402 (which may be optional), the base station initiates transmission of the received user data to the host computer. In step 2404 (which may be optional), the host computer receives the user data carried in the transmission initiated by the base station.

[0108] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.

Claims

1. A method performed by a wireless communication device (512) for activation of multiple Transmission Configuration Indication, TCI, states for a Physical Downlink Control Channel, PDCCH, in one or more Control Resource Sets, CORESETs, in a cellular communications system (500), the method comprising: receiving (600), from a network node (502; 506; 1700), a medium access control, MAC, control element, CE, signaling that activates two TCI states for one CORESET wherein the MAC CE signaling comprises: a first octet that comprises a serving cell identity, ID, of a serving cell of the wireless communication device (512) and a first part of a CORESET ID of the one CORESET; a second octet that comprises a second part of the CORESET ID of the one CORESET and a first TCI state ID of a first TCI state of the two TCI states that are activated for the one CORESET; and a third octet that comprises a second TCI state ID of a second TCI state of the two TCI states that are activated for the one CORESET.

2. The method of claim 1, wherein: - the method further comprises determining one of the first and the second TCI states as a default TCI state for physical downlink shared channel, PDSCH, scheduled by a physical control channel, PDCCH, received in the one CORESET; and / or - the one or more CORESETs consist of a single CORESET, and the two TCI states are activated for the single CORESET.

3. The method of claim 1 or 2 further comprising receiving (602) PDCCHs in the one or more CORESETs in accordance with the two TCI states that are activated for one or more CORESETs, optionally further comprising performing (604) one or more actions in accordance with downlink control information carried by the received PDCCHs.

4. The method of claim 3 wherein the received PDCCHs comprise two copies of a same DCI received from two or more respective transmission points, and the two or more respective transmission points correspond to two or more respective TCI states from among the two TCI states that are activated for one or more CORESETs, wherein, optionally, the two copies of the same DCI are received from the two or more respective transmission points in a same CORESET.

5. The method of any one of claims 1 to 4 wherein receiving (600) the MAC CE signaling that activates two TCI states for one CORESET comprises: receiving (700) a configuration of M TCI state lists for the one CORESET, wherein each TCI state list of the M TCI state lists comprises up to a predefined or preconfigured maximum number of TCI states and M > 1; and receiving (702), from the network node, an indication of one of the M TCI state lists for the one CORESET, wherein TCI states in the one of the M TCI state lists are the two TCI states that are activated for the one CORESET, wherein, optionally, the predefined or preconfigured maximum number of TCI states is greater than or equal to 2.

6. The method of claim 5 wherein: (a) (i) receiving (702) the indication of the one of the M TCI state lists for the CORESET comprises receiving (702) a Medium Access Control, MAC, Control Element, CE, that comprises the indication of the one of the M TCI state lists for the CORESET, or (ii) wherein the wireless communication device (512) interprets the TCI state ID as the indication of the one of the M TCI state lists for the CORESET; and / or (b) receiving (600) the MAC CE signaling that activates two TCI states for one CORESET comprises: receiving (1302), from the network node, a Medium Access Control, MAC, Control Element, CE, that comprises, for each CORESET of the one CORESET, information that indicates the two TCI states that are activated for the one CORESET.

7. The method of claim 6, feature group (b), wherein the MAC CE further comprises, for each TCI state of the two TCI states that are activated for the single CORESET, an indication of the TCI state.

8. A method performed by a network node (502) for activation of multiple Transmission Configuration Indication, TCI, states for a Physical Downlink Control Channel, PDCCH, in one or more Control Resource Sets, CORESETs, in a cellular communications system (500), the method comprising: sending (600), to a wireless communication device (512), a medium access control, MAC, control element, CE, signaling that activates two TCI states for one CORESET, wherein the MAC CE signaling comprises: a first octet that comprises a serving cell identity, ID, of a serving cell of the wireless communication device (512) and a first part of a CORESET ID of the one CORESET; a second octet that comprises a second part of the CORESET ID of the one CORESET and a first TCI state ID of a first TCI state of the two TCI states that are activated for the one CORESET; and a third octet that comprises a second TCI state ID of a second TCI state of the two TCI states that are activated for the one CORESET.

9. The method of claim 8 wherein: (a) the two TCI states are activated for the one CORESET; or (b) the MAC CE signaling comprises, for the one CORESET, information that indicates two TCI states activated for the one CORESET; or (c) sending (600) the MAC CE signaling that activates two TCI states for one CORESET comprises: sending (702), to the wireless communication device (512), the MAC CE that indicates of the two TCI states that are activated for the CORESET.

10. The method of claim 9, feature group (b), wherein: - the two TCI states are different for at least two of the two or more CORESETs; or - the two TCI states are the same for at least two of the two or more CORESETs11. The method of claim 8 wherein sending (600) the MAC CE signaling that activates two TCI states for one CORESET comprises: sending (700), to the wireless communication device (512), a configuration of M TCI state lists for the one CORESET, wherein each TCI state list of the M TCI state lists comprises up to a predefined or preconfigured maximum number of TCI states and M > 1; and sending (702), to the wireless communication device (512), an indication of one of the M TCI state lists for the one CORESET, wherein TCI states in the one of the M TCI state lists are the two TCI states that are activated for the one CORESET, wherein, optionally, the predefined or preconfigured maximum number of TCI states is greater than or equal to 2.

12. The method of claim 11 wherein: - sending (702) the indication of the one of the M TCI state lists for the one CORESET comprises sending a MAC CE that comprises the indication of the one of the M TCI state lists for the one CORESET; or - the TCI state ID is interpreted as the indication of the one of the M TCI state lists for the CORESET.

13. The method of claim 9, feature group (c), wherein the MAC CE comprises, for each TCI state of the two TCI states that are activated for the one CORESET, an indication of the TCI state.

14. The method of claim 13 wherein the MAC CE further comprises an indication of which of the two TCI states that are activated for the single CORESET is a default TCI state for physical downlink shared channel, PDSCH.

15. The method of any of claims 1 to 7 or 13 wherein the first TCI state indicated by the first TCI state ID in the second octet of the MAC CE is a default TCI state for physical downlink shared channel, PDSCH.

16. The method of any of claims 1 to 7 or any of claims 13 to 15 wherein: - the MAC CE is a fixed size MAC CE; or - the MAC CE is a flexible size MAC CE, wherein a size of the MAC CE is indicated by a length field of an associated header and the wireless communication device (512) interprets a value of two TCI states based on a value of the length field.

17. The method of claim 7 or 13 wherein the third octet of the MAC CE comprises a second part of the TCI state ID of the first TCI state of the two TCI states that are activated for the single CORESET.

18. The method of claim 7 or 8 wherein the MAC CE comprises: the third octet that further comprises a first part of a third TCI state ID of a third TCI state of the of the two TCI states that are activated for the single CORESET; and a fourth octet that comprises a second part of the third TCI state ID of the third TCI state of the of the two TCI states that are activated for the single CORESET.

19. The method of claim 18 wherein the MAC CE further comprises an indication of which of the two TCI states that are activated for the single CORESET is a default TCI state for physical downlink shared channel, PDSCH, wherein, optionally, the first TCI state indicated by the first TCI state ID in the second octet of the MAC CE is a default TCI state for physical downlink shared channel, PDSCH.

20. The method of claim 7 or 8 wherein the MAC CE comprises the third octet that further comprises an indication of whether a second TCI state of the two TCI states that are activated for the single CORESET is a default TCI state for physical downlink shared channel, PDSCH, wherein, optionally, the MAC CE further comprises a fourth octet that comprises: an indication of whether a third TCI state of the two TCI states that are activated for the single CORESET is a default TCI state for physical downlink shared channel, PDSCH; and a third TCI state ID of the third TCI state of the of the two TCI states that are activated for the single CORESET, wherein, further optionally, the one or more CORESETs comprise two or more CORESETs, and the MAC CE comprises, for each CORESET of the two or more CORESETs, for each TCI state of the two TCI states that are activated for the CORESET, an indication of the TCI state, wherein, further optionally, the MAC CE comprises the third octet that comprises an indication of whether additional octets are present, wherein, further optionally, the MAC CE further comprises: a first additional octet that comprises a second CORESET ID of a second CORESET of the two or more CORESETs; a second additional octet that comprises a first TCI state ID of a first TCI state of the two TCI states that are activated for the second CORESET; and a third octet that comprises: an indication of whether additional octets are present; and a second TCI state ID of a second TCI state of the two TCI states that are activated for the second CORESET.

21. A wireless communication device (512) for activation of multiple Transmission Configuration Indication, TCI, states for a Physical Downlink Control Channel, PDCCH, in one or more Control Resource Sets, CORESETs, in a cellular communications system (500), the wireless communication device (512) adapted to perform the method of: - any of claims 1 to 7; or - any of claims 15 to 20 when dependent on claim 1.

22. A network node (502) for activation of multiple Transmission Configuration Indication, TCI, states for a Physical Downlink Control Channel, PDCCH, in one or more Control Resource Sets, CORESETs, in a cellular communications system (500), the network node (502) adapted to perform the method of: - any of claims 8 to 14; or - any of claims 15 to 20 when dependent on claim 8.