Method and system for DCI and TCI schemes for beam management in massively distributed MIMO

Abstract

Several methods of providing downlink control information (DCI) and transmission configuration indication (TCI) for massively distributed MIMO and massively TRP are described herein. For example, a method for a hybrid DCI mechanism for massively distributed MIMO is described herein. For example, a method of a hierarchical DCI mechanism for massively distributed MIMO is also described herein. For example, a method of an enhanced transmit configuration indication (TCI) mechanism for massively distributed MIMO is also described herein. For example, a method of single DCI and multi-DCI dynamic switching for massively distributed MIMO is also described herein. For example, a method for DCI / TCI mechanism adaptation for massively distributed MIMO is also described herein.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 388,123, filed on July 11, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] Due to WTRU mobility, the WTRU may move between multiple transmit receive points (TRPs) and may be connected to multiple TRPs simultaneously. The current DCI mechanism may have been developed without considering large-scale TRPs. In addition, the transmission configuration indication (TCI) framework may have been developed without considering large-scale TRPs. Due to mobility and large-scale TRPs, the current design of downlink control information (DCI) for 2-TRPs and unified TCI for a single TRP may not be sufficient or optimal and needs to be enhanced. In addition, it may be necessary to extend to large-scale TRPs to support large-scale distributed MIMO deployments. There is also a need to extend the unified TCI to large-scale TRP scenarios. There is also a need to provide all DCI / TCI information required for large-scale TRPs while reducing signaling overhead and enhancing control coverage. Summary of the invention

[0004] A method and WTRU for switching between multiple DCI / TCI schemes are disclosed. The WTRU will transmit capabilities including resource allocation processing capabilities to the network. The WTRU will receive first configuration information for a first DCI / TCI scheme and use the first DCI / TCI scheme to receive an allocation of resources for receiving physical downlink shared channel (PDSCH) transmissions from multiple transmit receive points (TRPs). The WTRU will then receive second configuration information for a second DCI / TCI scheme and switch from the first DCI / TCI scheme to the second DCI / TCI scheme to receive an allocation of resources for receiving PDSCH transmissions from the multiple TRPs. The first DCI / TCI scheme may be a hierarchical DCI / TCI scheme and the second DCI / TCI scheme may be a hybrid DCI / TCI scheme. The hierarchical DCI / TCI scheme may include the WTRU: decoding a primary PDCCH (pPDCCH) transmission from one of the multiple TRPs, obtaining a common resource allocation for the TRP in the multiple TRPs, decoding a secondary PDCCH (sPDCCH) transmission and obtaining different TCIs for different TRPs, and detecting PDSCH transmissions using a common resource allocation (CRA) and beams indicated by the different TCIs for different TRPs in the multiple TRPs. The hybrid DCI / TCI scheme may include the WTRU: decoding a group PDCCH (gPDCCH) transmission from one of the multiple TRPs, obtaining a common resource allocation (CRA) and different TCIs for the TRP group, decoding gPDCCH transmissions from multiple TRP groups and obtaining different TCIs for the TRPs, and detecting PDSCH transmissions using the CRA for each TRP group and different beams indicated by the different TCIs for the TRP group.

[0005] The switch from the first DCI / TCI scheme to the second DCI / TCI scheme may be based on a MAC CE. The WTRU may send a PUSCH transmission to a TRP using the combined control information and TCI information for all TRPs obtained using the second DCI / TCI. Alternatively, the first DCI / TCI scheme is a multi-DCI / TCI scheme, or the first DCI / TCI scheme is a single DCI scheme.

[0006] Several other methods for providing downlink control information (DCI) and transmission configuration indication (TCI) for massive distributed MIMO and massive TRP are described herein. For example, a method for a hybrid DCI mechanism for massive distributed MIMO is described herein. For example, a method for a hierarchical DCI mechanism for massive distributed MIMO is also described herein. For example, a method for an enhanced transmission configuration indication TCI mechanism for massive distributed MIMO is also described herein. For example, a method for dynamic switching of a single DCI and multiple DCIs for massive distributed MIMO is also described herein. For example, a method for DCI / TCI mechanism adaptation for massive distributed MIMO is also described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate like elements, and in which:

[0008] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0009] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system;

[0010] Figure 1C is an example of an embodiment in which Figure 1A A system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0011] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0012] Figure 2 This is an example of a resource allocation scheme where a single PDCCH carries the DCI for all TRPs;

[0013] Figure 3 is an example of a hybrid DCI scheme or a single / multiple DCI scheme based on TRP groups;

[0014] Figure 4 is an example of a method for performing a hybrid DCI mechanism;

[0015] Figure 5 is an example multi-DCI scheme;

[0016] Figure 6is an example of a hierarchical DCI scheme, showing pDCI and sDCI;

[0017] Figure 7 is an example method of implementing a hierarchical PDCCH scheme;

[0018] Figure 8 is an example of a hierarchical DCI scheme, showing G-pDCI+sDCI;

[0019] Fig. 9 is an example method of performing hierarchical PDCCH for supporting partially overlapping resource allocations;

[0020] Fig.10 is an example method of implementing a hierarchical PDCCH scheme;

[0021] Fig.11 is another example method of implementing a hierarchical PDCCH scheme;

[0022] Fig.12 is another example of a method for performing fast TCI indication;

[0023] Fig.13 is an example scheme of using TCI pairs for M TRPs;

[0024] Fig.14 is an example scheme of using TRP grouping to apply TCI pairs to M TRPs;

[0025] Fig.15 is an example scheme for using TCI pairs for M TRPs through TRP grouping 2;

[0026] Fig.16 is an example method for TCI for massive distributed MIMO;

[0027] Fig.17 is a method for performing DCI scheme switching;

[0028] Fig.18 is an example method of performing DCI / TCI scheme adaptation; and

[0029] Fig.19 is another example method of performing DCI / TCI scheme adaptation. DETAILED DESCRIPTION

[0030] Figure 1A1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, and filter bank multi-carrier (FBMC), etc.

[0031] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a station (STA)) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), consumer electronic devices, and devices operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0032] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a Next Generation Node B (such as a gNode B (gNB)), a New Radio (NR) Node B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0033] Base station 114a may be part of RAN 104, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSC), radio network controllers (RNC), and relay nodes. Base station 114a and / or base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of a licensed spectrum and an unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Therefore, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0034] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0035] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA, among others. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), that may use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA may include communication protocols, such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​Uplink (UL) Packet Access (HSUPA).

[0036] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0037] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology (such as NR radio access) that may establish the air interface 116 using NR.

[0038] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using the dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0039] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0040] Figure 1A The base station 114b in may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as commercial venues, homes, vehicles, campuses, industrial facilities, sky corridors (e.g., for use by drones), and roads. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.11) to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.15) to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, the base station 114 b may have a direct connection to the Internet 110. Therefore, the base station 114 b may not need to access the Internet 110 via the CN 106.

[0041] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the specification, the CN 106 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. Figure 1AAlthough not shown in the figure, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0042] The CN 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0043] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0044] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0045] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0046] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from a base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV, or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0047] Although the transmit / receive element 122 Figure 1B Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0048] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0049] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, and a secure digital (SD) memory card, among others. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0050] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0051] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0052] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, Modules, frequency modulation (FM) radio units, digital music players, media players, video game player modules, Internet browsers, virtual reality and / or augmented reality (VR / AR) devices and activity trackers, etc. The peripheral device 138 may include one or more sensors. The sensor may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geographic location sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and a humidity sensor, etc.

[0053] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous.

[0054] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0055] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0056] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, and scheduling of users in the UL and / or DL, among other things. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0057] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0058] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, and selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0059] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0060] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0061] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0062] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0063] In a representative embodiment, the other network 112 may be a WLAN.

[0064] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and destined for the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and destined for a target outside the BSS may be transmitted to the AP to be delivered to the corresponding target. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the target STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between the source STA and the target STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0065] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may send beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0066] High throughput (HT) STAs may communicate using a 40 MHz wide channel (eg, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels) to form a 40 MHz wide channel.

[0067] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and the data can be sent by sending STA. At the receiver of the receiving STA, the above-mentioned operation for 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0068] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0069] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (which only supports a 1MHz operating mode) is transmitting to the AP, all available bands may be considered busy even if most of the available bands remain idle.

[0070] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0071] Figure 1D1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0072] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0073] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0074] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeB 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0075] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, interworking between DC, NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b and routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0076] Figure 1D The illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although the aforementioned elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0077] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, and mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, and services for MTC access. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0078] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing DL data notifications. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0079] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, and providing mobility anchoring, etc.

[0080] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the local DNs 185a, 185b.

[0081] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU102a to 102d, base station 114a to 114b, evolved Node B 160a to 160c, MME 162, SGW 164, PGW 166, gNB180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0082] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. A simulation device may be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communications.

[0083] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0084] “Massive TRP” refers to a large number of TRPs. “Massive MIMO” refers to a large number of antennas per TRP. “Distributed massive MIMO” refers to multiple TRPs, each with a large number of antennas. “Massive distributed MIMO” refers to a large number of TRPs (i.e., “massive TRPs”).

[0085] The following abbreviations and acronyms may be referenced herein.

[0086] BFD-RS Beam Fault Detection Reference Signal

[0087] BFR Beam Failure Recovery

[0088] BFRQ Beam Failure Recovery Request

[0089] BLER Block Error Rate

[0090] BFI beam failure example

[0091] CORESET Control Resource Set

[0092] CRI CSI-RS Resource Index

[0093] CSI-RS Channel State Information Reference Signal

[0094] DCI Downlink Control Information

[0095] JT Joint Send

[0096] L1-RSRP Layer 1 reference signal received power

[0097] L1-SINR Layer 1 signal to interference plus noise ratio

[0098] NBI-RS New Beam Identification Reference Signal

[0099] NW Network

[0100] PDCCH Physical Downlink Control Channel

[0101] RS reference signal

[0102] SSBRI SSB Resource Index

[0103] TCI Send Configuration Indication

[0104] TDD Time Division Duplex

[0105] TRP Send and Receive Points

[0106] In 5G NR, the TCI framework is introduced. Unified TCI for a single TRP can be supported. For non-unified TCI, operation of only two TRPs is supported, and coherent joint transmission between TRPs is not supported. In addition, the TCI framework can only support the use of one TCI code point to indicate a maximum of 2 TCI states. The TCI framework also supports the frequency ranges of FR1 and FR2.

[0107] For multi-TRP operation, dynamic TRP selection can be supported. Mobility measurements for multi-beam / multi-TRP deployments can also be supported, with up to 64 SSBs per cell. Multi-TRP transmission of PDSCH for eMBB can also be supported. In addition, multi-TRP diversity for URLLC is supported. Multi-TRP operation based on 2 TRPs can also be supported. In addition, inter-cell multi-TRP operation can be supported. In addition, inter-cell multi-TPR operation without handover can be supported. Multi-TRP repetition for PDCCH, PUCCH and PUSCH can also be supported.

[0108] The CSI-RS framework may support CSI interference measurements based on ZP-CSI-RS (e.g., CSI-IM resources) and / or NZP-CSI-RS resources. Type II codebooks for high-resolution CSI feedback may also be supported. Enhancements to Type II codebooks may also be supported. CSI enhancements for multi-TRP non-coherent joint transmission (NCJT) may also be supported.

[0109] In a highly dense network, the WTRU may be connected to a massive TRP in a massive distributed MIMO scenario. The WTRU may receive data from a massive TRP via a DL data channel (e.g., PDSCH) or may send data to a massive TRP via an UL data channel (e.g., PUSCH). Such transmission or reception may be coherent or non-coherent. The WTRU may first receive downlink control information (DCI) from one or more TRPs via a DL control channel transmission (e.g., PDCCH).

[0110] When DCI is sent from a single TRP to enable data to be received from or sent to a large-scale TRP, the DCI payload size may be larger if additional bits are required in the DCI to support the large number of TRPs, such as repeated fields (e.g., TCI fields) or field extensions (e.g., to support a large number of TCI code points). As the number of TRPs increases, the DCI payload size also increases. The increased DCI payload size may degrade the performance of the PDCCH and reduce the coverage of the DCI. In large-scale distributed MIMO deployments, a single DCI scheme may require additional bits to support a large number of TRPs. A multiple DCI scheme may require additional PDCCHs to support a large number of TRPs. A compromise between a single DCI scheme and a multiple DCI scheme may be considered.

[0111] It is also proposed herein that the proposed WTRU may be configured to perform adaptation mechanisms for the operations and processes of multiple DCI / TCI schemes for massive distributed MIMO. The DCI / TCI scheme may be adapted to optimize spectral efficiency, minimize signaling overhead, and achieve system scheduling and operational flexibility. The DCI / TCI scheme may be adapted between multiple DCI / TCI schemes such as a single DCI scheme, a multiple DCI scheme, a hybrid DCI scheme, and a hierarchical DCI scheme. DCI / TCI adaptation may be determined based on specific criteria, including but not limited to transmission type, resource allocation type, and resource overlap type. The transmission type may be coherent or non-coherent joint transmission. The resource allocation type may be overlapping or non-overlapping resources. The resource overlap type may be fully overlapping or partially overlapping. According to the implementation scheme proposed herein, the WTRU may be configured with multiple DCI schemes. Resources may be allocated for PDSCH transmission of TRP.

[0112] The WTRU may report capabilities including resource allocation capabilities. If the transmission type is determined to be a non-coherent joint transmission, the resource allocation type is further determined. If the resource allocation type is determined to be an overlapping type, the resource overlap type is further determined. If the determined resource overlap type is a partial overlap, the hybrid DCI scheme is activated and enabled (for example, in the MAC CE). The WTRU will decode the gPDCCH of one TRP from each TRP group. The WTRU will then obtain common resource allocations for the TRP group but different TCIs (obtained via gDCI), decode the gPDCCHs from multiple TRP groups and obtain different TCIs.

[0113] Figure 2 A single DCI resource allocation scheme 200 for a scenario with multiple TRPs 210 is depicted in FIG.

[0114] exist Figure 2 In the embodiment, a single PDCCH carrying DCI 220 for all TRPs 210, 240 is sent from one of the TRPs 240 to the WTRU 230. The single DCI 220 contains control information for a large number of TRPs for detecting PDSCH or transmitting PUSCH.

[0115] Some common control fields can be shared between large-scale TRPs to reduce the DCI payload size. For example, the common control field can be a resource allocation field. In one example, for a single DCI 230, the same frequency-time resources can be allocated, and different layers can be sent from different TRPs. In addition, some control fields can be made common in specific cases. For example, modulation and coding (MCS) can be made common at the expense of reduced link adaptation flexibility. Doing so can reduce the DCI payload size, but system flexibility may be reduced.

[0116] For coherent operation, resource allocation may be common, so in this scenario, the control field for resource allocation may be common to all TRPs. On the other hand, for incoherent operation, resource allocation may not necessarily be common, so in this scenario, the control field for resource allocation may not be common to all TRPs. Therefore, the DCI operation related to the usage scenario can be considered based on whether the operation is coherent or incoherent. The DCI operation mode can be configured by RRC. Alternatively, multiple DCI operation modes can be configured by RRC, and the exact DCI operation mode to be used can be activated or indicated by MAC CE or DCI.

[0117] Two types of DCI for massive distributed MIMO may be utilized, one type of DCI (such as type ADCI) may be used for low payload DCI, and another type of DCI (such as type B DCI) may be used for high payload DCI. For coherent operation, type B DCI may be used, while for non-coherent operation, both type A and type B DCI may be used, depending on the scenario and tradeoff. Two DCI formats may be developed for type A DCI and type B DCI for massive distributed MIMO.

[0118] In addition, scalable DCI can be used. Depending on the number of TRPs to which the WTRU is connected, the DCI can be large or small. However, if the DCI is very large, the performance of the PDCCH may be impaired. Therefore, the maximum number of TRPs to which the WTRU can be connected may be limited. This number M may be configurable. The maximum number of TCI states for each TCI code point or the number of CORESET pools may be determined based on the maximum number of TRPs. For example, when extracting a subset of TCI states defined in the PDSCH-Config and activating / deactivating a specific TCI state, a list (subset) of TCI states to be activated / deactivated is configured through a bitmap. If the bit at a specific position is set to "1", the TCI state mapped to the bit position is activated. If the bit is set to "0", the TCI state mapped to the bit position is deactivated. A list of bit positions set to "1" is assigned to a table or code point.

[0119] TRP grouping may be used. Within the same TRP group, a single DCI may be used. A CORESET or CORESET pool may be associated with each TRP group. Between TRP groups, multiple DCIs may be used. Up to M TRPs may be used in a TRP group to support a reasonable DCI payload size. There may be N TRP groups to which the WTRU may be connected. Therefore, for WTRU connections in massively distributed MIMO, MxN TRPs may be supported. There may also be a maximum number of single DCIs allowed. This number may correspond to N and may also be configurable. TRP grouping may be based on TRP type, DCI mechanism, control transmission scheme (e.g., single DCI scheme, multiple DCI scheme, hybrid DCI scheme, hierarchical DCI scheme, and variants of the foregoing, etc.), DCI payload size, data transmission scheme (e.g., coherent or incoherent joint transmission, diversity transmission), WTRU measurements (including RSRP), WTRU capabilities, QoS requirements (such as reliability), WTRU mobility, etc. The WTRU may report some or all of the above information to the gNB to assist in TRP grouping. The WTRU may also perform automatic TRP grouping based on the available information described above.

[0120] A hybrid DCI scheme may be developed and utilized. The hybrid DCI scheme may support a single DCI scheduling multiple TRPs and multiple DCI scheduling multiple TRPs (or TRP groups). The hybrid DCI scheme may achieve a trade-off between DCI payload size and performance.

[0121] For massively distributed MIMO, two operating modes may be supported. Mode 1 may support a fixed or configurable number of TRPs for each WTRU connection. Mode 2 may support a variable or dynamic number of TRPs for each WTRU connection. The maximum number of TRPs for a WTRU connection may be (pre)configured based on the DCI operating mode. In addition, the maximum number of TRPs for a WTRU connection may be determined by or based on the DCI mechanism, control transmission scheme, DCI payload size, data transmission scheme (e.g., coherent or incoherent joint transmission, diversity transmission), WTRU measurements (including RSRP), WTRU capabilities, QoS requirements (such as reliability), WTRU mobility, and the like.

[0122] In Mode 1 operation, if the control field or code point indicates a TRP index, a CORESET index, a CORESET pool index, etc. and a corresponding TCI state, the WTRU may receive PDSCH in massively distributed MIMO from beams of the indicated TRP and TCI state. For those TRPs that are not indicated, the WTRU may maintain the same TRP and the same beam for PDSCH reception. TCI updates may only occur when TCI is indicated. If TCI is not indicated, the same TCI state may be reused. In Mode 2 operation, if the control field or code point indicates a TRP index and a corresponding TCI state, the WTRU may receive PDSCH transmissions in massively distributed MIMO from beams of the indicated TRP and / or TCI state. However, for those TRPs that are not indicated, the WTRU may remove those TRPs and beams used for PDSCH reception. If TCI is not indicated, the corresponding TCI state may not be used. A set of TRPs and TCI states may be indicated in the DCI and used at the WTRU. Similarly, these operating modes may also be applied to the uplink. In addition, the operation mode can be applied to DL and UL simultaneously, separately or jointly (this is also configurable). The activated TCI state can be associated with the TRP. The TRP can also be implicitly identified by the activated TCI state.

[0123] Figure 3An example approach for a hybrid DCI mechanism is depicted in . Even for completely overlapping resources, if the number of TRPs is large, the DCI size needs to be significantly increased, otherwise scheduling flexibility may be limited, resulting in reduced coverage and performance. In addition, the number of TRPs performing joint transmission (coherent or incoherent joint transmission) or diversity transmission (for example, by TDM, FDM, SDM, or point selection of TRPs) may be different. This may result in variable DCI sizes. Therefore, when using a single DCI, there may be restrictions or constraints on the number of TRPs. However, when the number of TRPs is limited, many TRPs may not be supported. Therefore, a hybrid DCI scheme that utilizes a joint design of a single DCI scheme and a multiple DCI scheme may be introduced.

[0124] like Figure 3 As shown, a TRP group is formed by three TRPs in each arc. Each TRP group can jointly send PDCCH using a single DCI scheme. This PDCCH is called a group PDCCH or gPDCCH. There are four TRP groups, so three gPDCCHs are sent. Between multiple TRP groups, a multi-gPDCCH scheme is used.

[0125] One solution may be to use common TRP group information to achieve lower overhead. For each TRP group, the frequency and / or time resources may be common, and a group PDCCH or gPDCCH may be used to carry control information for each TRP group. Multiple gPDCCHs may be used to carry control information for multiple TRP groups.

[0126] At least two types of DCI formats may be used, with one DCI format being optimized for larger DCI payloads to support a large number of TRPs and the other DCI format being used for normal DCI payloads. Which DCI format to use may depend on the number of TRPs to be connected and the WTRU capabilities.

[0127] TRP discarding rules may be used. In the event that the number of TRPs to be connected exceeds a (pre)configured threshold, some TRPs may be discarded. The discarding of TRPs may be determined by the WTRU. The discarding of TRPs may be based on measurements, priorities, and the like. For example, the measurements may be based on RSRP. Other formats and parameters may also be used to measure signal power or make a decision to discard a TRP. Priorities may be assigned to TRPs. Different types of TRPs may be deployed and assigned different priorities. For example, some TRPs may employ traditional MIMO technology (e.g., linear, planar, circular, etc. antenna arrays), while other TRPs may employ holographic MIMO technology. In one example, holographic MIMO is facilitated with an ultra-thin, extremely large, and nearly continuous surface that combines reconfigurable and sub-wavelength spaced antennas and / or metamaterials. A higher priority may be assigned to a holographic TRP and a lower priority may be assigned to a traditional TRP, and vice versa. When a TRP is discarded, the WTRU may not monitor the PDCCH for the CORESET associated with the discarded TRP, and may not expect to receive PDSCH or send PUSCH for the discarded TRP. Discarding a TRP may mean deactivating the TCI state in one or more CORESETs or TCI codepoints (corresponding to the TRP), or deactivating the CORESET and / or search space set associated with the discarded TRP.

[0128] Figure 4 An example process 400 for receiving resource allocations using a hybrid DCI mechanism is depicted in . At 410, the WTRU may be configured for the hybrid DCI mechanism. At 420, the WTRU may be configured with a CORESET and / or a pool of CORESETs for hybrid DCI. Such configuration may be for TRP groups. The WTRU may monitor the PDCCH in the search space of the CORESET associated with each TRP group to obtain DCI at 430, and decode the PDCCH of each TRP group and all TRP groups accordingly at 440. At 450, the WTRU may combine all or some of the DCI decoded in the PDCCH to obtain control information for all TRPs. Then, at 460, the WTRU may detect and demodulate the PDSCH using the combined obtained control information for all TRPs.

[0129] Alternatively, at 450, the DCI combination may be based on an indicator, the same HARQ process, the same resource allocation (eg, time domain resource allocation (TDRA)), or based on a PDCCH association configured via RRC.

[0130] This article discusses methods for a hierarchical DCI mechanism for massive distributed MIMO or massive TRPs. In the case of a multi-DCI mechanism, a PDCCH carrying DCI is transmitted from each TRP. In this case, there are multiple PDCCHs carrying multiple DCIs transmitted from multiple TRPs. Each DCI carries control information for each TRP, including resource allocation information. The resource allocation information can be common to all TRPs. If the resource allocation information is common to all TRPs, the same resource allocation information is repeated in each DCI, which is not efficient for resource utilization. In massive distributed MIMO deployments, a large number of TRPs are used. For a large number of TRPs, the same resource allocation information is repeated in each DCI, which significantly reduces resource utilization efficiency.

[0131] In a highly dense network, the WTRU may be connected to a massive TRP in a massive distributed MIMO scenario. The WTRU may receive data from a massive TRP via a DL data channel (e.g., PDSCH), or may send data to a massive TRP via a UL data channel (e.g., PUSCH). Such transmission or reception may be coherent or incoherent. The WTRU may first receive downlink control information (DCI) from one or more TRPs via a DL control channel (e.g., PDCCH). When DCI is sent from multiple TRPs to enable data to be received from or sent to a massive TRP, the number of DCIs may be larger. As the number of TRPs increases, the number of PDCCHs also increases. An increase in the number of PDCCHs may increase blind decoding attempts and decoding complexity as well as PDCCH blocking.

[0132] For non-coherent joint transmission using multiple DCIs, the frequency-time resources may completely overlap, and in such a scheme, the primary DCI or pDCI may carry overlapping information. In this case, it may not be efficient to repeat the resource allocation information in each DCI of the multiple DCIs. This may result in a waste of resources and increase overhead. For multiple DCIs, a solution is needed to enhance PDCCH performance and reduce DCI payload.

[0133] Figure 5 An example multi-DCI mechanism 500 is shown. A PDCCH carrying a DCI is sent from each TRP 510. There are multiple PDCCHs carrying multiple DCIs 520 sent from multiple TRPs. Each DCI carries control information for each TRP, including resource allocation information. The resource allocation information can be common to all TRPs. If the resource allocation information is common to all TRPs, the same resource allocation information is repeated in each DCI, which is not efficient for resource utilization.

[0134] A solution of hierarchical DCI mechanism is proposed. In this solution, primary DCI and secondary DCI are introduced. Primary DCI or pDCI is used to carry TRP common information. Secondary DCI or sDCI is used to carry TRP specific information. pDCI is carried by primary PDCCH or pPDCCH. sDCI is carried in secondary PDCCH or sPDCCH. pDCI can be designed to have a small payload, and its performance can be very robust by design.

[0135] Figure 6 An example method of a hierarchical DCI mechanism 600 for pDCI and sDCI is depicted. In a multi-DCI scheme, the frequency-time resources from the TRPs may completely overlap. It may also depend on the WTRU capabilities. In this case, different PDSCH / PUSCH are sent from different TRPs. pDCI 620 may be used to carry overlapping resource information.

[0136] exist Figure 6 In the hierarchical DCI mechanism of FIG. 6 , a primary DCI 620 or pDCI is sent from one of the TRPs 605. The pDCI 620 may carry key control information of the TRPs 605, 610 and / or TRP common control information. In addition, the secondary DCI 630 or sDCI may carry TRP specific control information. The pDCI 620 may carry information such as resource allocation or other information common to all TRPs 610.

[0137] In the extended hierarchical DCI mechanism, TRPs can be grouped into several groups. The main DCI or pDCI is sent from one TRP in each TRP group. The pDCI may carry key control information of the connected TRP and / or TRP group common control information. In addition, the secondary DCI or sDCI may carry TRP-specific control information. The pDCI may carry information such as resource allocation or other information common to all TRPs in each TRP group.

[0138] In the case of multiple DCI, pDCI may carry resource allocation information for completely overlapping resources between TRPs. pDCI may carry overlapping information for coherent joint transmission where frequency-time resources may overlap, or in non-coherent joint transmission where frequency-time resources may be forced to completely overlap. sDCI may carry any other remaining control information.

[0139] For partially overlapping resources between TRPs, pDCI can carry partially overlapping resource allocation information. In non-coherent joint transmission where frequency and time resources can partially overlap, pDCI can carry partially overlapping information. In this case, sDCI can carry non-overlapping information between TRPs.

[0140] Figure 7An example method 700 of a hierarchical PDCCH mechanism is depicted. At 710, the WTRU may be configured for a hierarchical DCI mode of operation. At 720, the WTRU may decode a primary PDCCH or a pPDCCH. At 730, after successfully decoding the primary PDCCH or the pPDCCH, the WTRU may obtain the primary DCI or the pDCI. The WTRU may obtain TRP common control information in the primary DCI or the pDCI. At 740, the WTRU may also decode a secondary PDCCH or an sPDCCH. After successfully decoding the secondary PDCCH or the sPDCCH, the WTRU may obtain the secondary DCI or the sDCI. The WTRU may obtain TRP specific control information in the secondary DCI or the sDCI. At 750, the WTRU may combine the TRP common control information and the TRP specific control information for all TRPs. At 760, the WTRU may detect PDSCH transmissions using the combined primary control information and the secondary control information of all TRPs or the TRP common control information and the TRP specific control information.

[0141] Figure 8 An example method 800 for a hierarchical DCI mechanism for G-pDCI+sDCI is shown. The method may also be referred to as a hierarchical hybrid DCI (HH-DCI) scheme. The frequency time resources may be fully overlapping, partially overlapping, or non-overlapping. Different PDSCH / PUSCH may be sent from a TRP. Non-overlapping may be mandatory. Depending on the WTRU capabilities, full or partial overlap may also be supported. The WTRU may report its capabilities.

[0142] In a hierarchical DCI mechanism for multiple DCIs, a primary group DCI or G-pDCI is sent from one of the TRPs in a TRP group. The G-pDCI may carry key control information and / or group common control information for the TRP group. In addition, the secondary DCI or sDCI may carry TRP-specific control information for each TRP of the TRP group. The G-pDCI may carry information such as resource allocation or other information.

[0143] For non-coherent joint transmission, for overlapping resources between TRPs, G-pDCI can carry overlapping resource allocation information of TRP groups. The number of PDCCHs may not be reduced, but the payload size can be reduced. Since in multi-DCI of M TRPs, M PDCCHs are required. In hierarchical DCI, M+1 PDCCHs are required. But in hierarchical DCI, sPDCCH has a reduced payload size to carry TRP-specific information. Therefore, the total overhead is reduced.

[0144] Both single DCI and multiple DCI can support coherent joint transmission. For coherent joint transmission using single DCI, the frequency and time resources are completely overlapped, and in such schemes, single DCI can carry overlapping information. For non-coherent joint transmission using multiple DCI, the frequency and time resources can be completely overlapped. In such schemes, pDCI can carry overlapping information. In this case, it may not be efficient to repeat resource allocation information in each DCI of multiple DCI. This will result in waste of resources and increase overhead. For non-overlapping cases, multiple DCIs may be sufficient. For partial overlap, hybrid hierarchical DCI can be used. In this case, in multiple DCIs, some partial common information is carried in pPDCCH, and some non-overlapping information is carried in each sPDCCH in sPDCCH.

[0145] For non-coherent or coherent joint transmission using multiple DCIs, the frequency-time resources may be completely overlapping. In such a scheme, the pPDCCH with pDCI in multiple DCIs may carry overlapping information that is completely overlapping or partially overlapping. The sPDCCH with sDCI may carry any other non-overlapping information between TRPs.

[0146] For non-coherent joint transmission, partial overlap may occur. In partial overlap, sometimes some TRPs may have overlapping information, but other TRPs may not have overlapping information. In this case, it may be beneficial to group the TRPs based on the overlapping condition. For non-overlapping cases, it is possible to fall back to a multi-DCI scheme in which each DCI carries its own resource information. For full overlap, it is possible to fall back to a single DCI scheme. In order to form a TRP group, the WTRU may report measurements, such as performing measurements on the CSI-RS and reporting the measurements to the network, and the network may decide on the grouping of the TRPs based on the measurements. Alternatively, the WTRU may also recommend the grouping of the TRPs and transmit the recommendation to the network. Another solution is that the WTRU may initiate grouping and / or decide on the grouping of the TRPs, and then notify the network of the decision. The measurements may include L1-RSRP, L1-RSRQ, CSI-RS Resource Index (CRI), L1-SINR, etc. or a combination thereof.

[0147] As previously mentioned, group pDCI or G-pDCI can be used. TRPs can be in a group. A pDCI representing the TRP group can be sent. Such pDCI is called G-pDCI. In the example, four TRP groups are shown. Each TRP group sends a G-pDCI. In each TRP group, a separate sDCI is sent for each TRP. TRPs can be grouped based on specific criteria. For example, TRP grouping can be based on maximization of overlapping resources. If the resources are not completely overlapping, these resources can belong to separate TRP groups. Other criteria can also be applied to TRP grouping.

[0148] Several methods for downlink control information (DCI) and transmission configuration indication (TCI) for massive distributed MIMO and massive TRP are proposed.

[0149] A hybrid DCI scheme is proposed, in which a TRP group PDCCH or gPDCCH is used to carry group DCI or gDCI for control information of a TRP group. Multiple gDCI or multiple gDCIs may be sent for multiple TRP groups. Each gDCI may contain control information for a TRP for PDSCH reception or PUSCH transmission. Each gDCI may contain control information including resource allocation, TCI information, and the like. Resource allocation information may include frequency domain resource allocation (FDRA), time domain resource allocation (TDRA), and the like. In order to maintain signaling overhead and scheduling flexibility, a gPDCCH may be sent from a TRP group, the size of which may be maintained at a reasonable and optimized size so that the signaling overhead may be low and the scheduling flexibility may be high.

[0150] A hierarchical DCI scheme is proposed in which a primary PDCCH or pPDCCH and a secondary PDCCH or sPDCCH are sent. The primary PDCCH or pPDCCH may carry primary DCI or pDCI, and the secondary PDCCH may carry secondary DCI or sDCI. The primary DCI or pDCI may carry control information that is common or critical to the TRP, and the secondary DCI or sDCI may carry control information specific to the TRP. This may minimize signaling overhead. The primary DCI or pDCI may carry common resource allocation information or overlapping resource allocation information, and the secondary DCI or sDCI may carry other control information including TCI information. An alternative may be that the primary DCI or pDCI may carry control information that may be specific to the TRP, and the secondary DCI or sDCI may carry another set of control information, which may also be specific to the TRP. Another alternative may be that the primary DCI or pDCI may carry TRP-specific resource allocation information or non-overlapping resource allocation information (e.g., TDRA, FDRA), and the secondary DCI or sDCI may carry other control information including TCI information. Yet another alternative may be that the primary DCI or pDCI may carry TRP-specific resource allocation information or non-overlapping resource allocation information (e.g., TDRA, FDRA) and TCI information, and the secondary DCI or sDCI may carry the remaining control information or other control information.

[0151] A combination of a hybrid DCI scheme and a hierarchical DCI scheme (hierarchical hybrid or HH-DCI) is also possible. For example, each TRP group can send a TRP group pDCI or a G-pDCI. Multiple G-pDCIs can be sent for multiple TRP groups. Each TRP group can send multiple sDCIs.

[0152] A solution for fast TCI indication and support for a large number of TRPs is proposed. The solution may be to use one or more secondary TCI fields for TCI indication of PDCCH to achieve fast TCI indication. In addition, one or more secondary TCI fields may also be used to support more TCI states for large-scale distributed MIMO. When a second TCI field is present, very fast indication and switching may be achieved. DCI may be used to indicate TCI states for control and data, respectively. The WTRU may be configured for TCI states. The WTRU may monitor the PDCCH based on the configuration. The WTRU may detect PDCCH transmission and decode the DCI. If the second TCI field is configured, the WTRU may obtain TCI information from the second TCI field in the DCI. The WTRU may decode the next PDCCH using the beam indicated in the TCI of the second TCI field. If the second TCI field is not configured, the WTRU may obtain TCI from the MAC CE. The WTRU may decode the next PDCCH using the beam indicated in the MAC CE. The WTRU may obtain TCI from the first TCI field in the DCI. The WTRU may detect the current PDSCH using the beam indicated in the TCI of the first TCI field in the DCI. In order to support a large number of TRPs, the WTRU may be configured for TCI states. The WTRU may report TCI changes for a TRP. The WTRU may receive a reactivated TCI state via a MAC CE based on the reported TCI state changes. The WTRU may receive, for example, TCI information in a DCI, where the TCI indication may point to a reactivated code point in a MAC CE. The WTRU may receive other control information for all TRPs. The WTRU may detect and decode PDSCH transmissions using the beam indicated in the TCI state of all TRPs.

[0153] An adaptation mechanism for multiple DCI schemes is proposed, in which a DCI scheme is selected based on specific criteria and conditions (e.g., transmission type, resource allocation type, resource overlap type, etc.). The DCI / TCI scheme can be adapted to optimize spectral efficiency, minimize signaling overhead, and achieve scheduling and operational flexibility of the system. The DCI / TCI scheme can be adapted between multiple DCI / TCI schemes such as a single DCI scheme, a multiple DCI scheme, a hybrid DCI scheme, and a hierarchical DCI scheme. DCI / TCI adaptation can be determined based on specific criteria, including but not limited to transmission type, resource allocation type, and resource overlap type. The transmission type can be coherent or non-coherent joint transmission. The resource allocation type can be overlapping or non-overlapping resources. The resource overlap type can be fully overlapping or partially overlapping.

[0154] The DCI / TCI scheme may be adapted based on the number of DCIs (or PDCCHs) sent, the number of TRPs, and so on. The WTRU may be configured with multiple DCI schemes. Completely overlapping resources may be allocated for PDSCH transmission (or PUSCH) of TRPs. If it is determined that several DCIs are to be sent, the number of TRPs is further determined. If the number of TRPs is greater than a (pre) configured threshold, the hierarchical DCI scheme may be activated and enabled (e.g., in a MAC CE). The WTRU may decode pPDCCH from one TRP. The WTRU may obtain a common resource allocation for the TRP. The WTRU may decode sPDCCHs from multiple TRPs and obtain different TCIs for the TRPs via sDCI. The WTRU may detect PDSCH transmissions using the common resource allocation obtained via pDCI and the different beams indicated by the TCI of the TRP obtained via sDCI. If the number of TRPs is not greater than or less than a (pre) configured threshold, the multi-DCI scheme may be activated and enabled (e.g., in a MAC CE). The WTRU may decode multiple PDCCHs from multiple TRPs. The WTRU may obtain different resource allocations and TCIs for the TRPs. The WTRU may detect PDSCH transmissions using separate resource allocations and different beams indicated by the TCI of the TRPs. If it is determined that several DCIs are not to be sent, and it is determined that only a single DCI is to be sent, the single DCI scheme may be activated and enabled (e.g., in a MAC CE). The WTRU may decode a single PDCCH transmission from a single TRP.

[0155] Fig. 9 An example method 900 for a hierarchical PDCCH mechanism to support partially overlapping resource allocations is shown. At 910, a WTRU may be configured to operate in a hierarchical DCI mode. At 915, a WTRU may decode a primary PDCCH or a pPDCCH. At 920, a WTRU may obtain common control information or a portion of common control information via a pPDCCH.

[0156] The WTRU may be scheduled for data reception or transmission via resource allocations in a DCI in, for example, a pPDCCH transmission. At 930, different DCI types may be used depending on the resource allocation conditions (whether it is fully overlapping or partially overlapping). If the resource allocations are fully overlapping, at 935, hierarchical DCI type 1 may be activated and enabled. For example, the hierarchical DCI type may be activated and enabled via a MAC CE. At 940, the WTRU may decode a secondary PDCCH transmission or an sPDCCH transmission that may not include resource allocation information for a TRP. At 945, the WTRU may obtain TCI information in the secondary PDCCH or sPDCCH and other control information other than the resource allocation information. At 950, the WTRU may use the resource allocation information in the pPDCCH and the TCI and other control information in the sPDCCH, and detect the PDSCH transmission using the indicated resource allocations and different beams indicated by the TCI of the TRP.

[0157] If the resource allocations partially overlap, then at 955, a hierarchical DCI type 2 may be activated and enabled. For example, the hierarchical DCI type may be activated and enabled via a MAC CE. At 960, the WTRU may decode the sPDCCH including resource information from each TRP. At 965, the WTRU may obtain different partially non-overlapping resource allocation information and TCI for the TRP in the sPDCCH. At 970, the WTRU may combine the resource allocation information in both the pPDCCH and the sPDCCH and detect the PDSCH transmission using the combined resource allocation and different beams indicated by the TCI of the TRP.

[0158] Fig.10 An example method 1000 for resource allocation using a hierarchical PDCCH mechanism (TCI information in pDCI) is shown. At 1010, the WTRU may be configured for a hierarchical DCI scheme. At 1015, the WTRU may decode the pPDCCH to obtain the pDCI. At 1020, the WTRU may obtain TRP-specific part 1 information for resource allocation and TCI information for all TRPs in the pDCI via the pPDCCH. At 1025, the WTRU may decode the sPDCCH to obtain the sDCI. At 1030, the WTRU may obtain TRP-specific part 2 information for the remaining control information for all TRPs in the sDCI via the sPDCCH. At 1035, the WTRU may combine the TRP-specific part 1 control information and the TRP-specific part 2 control information. At 1040, the WTRU may detect the PDSCH transmission using the combined TRP-specific part 1 (pDCI) and TRP-specific part 2 (sDCI) control information for all TRPs.

[0159] Fig.11An example method 1100 for resource allocation using a hierarchical PDCCH mechanism (TCI information in sDCI) is shown. At 1110, the WTRU may be configured for a hierarchical DCI scheme. At 1120, the WTRU may decode the pPDCCH to obtain the pDCI. At 1130, the WTRU may obtain TRP-specific part 1 control information for resource allocation for all TRPs in the pDCI via the pPDCCH. At 1140, the WTRU may decode the sPDCCH to obtain the sDCI. At 1150, the WTRU may obtain TRP-specific part 2 control information for the remaining control information (including TCI information) for all TRPs in the sDCI via the sPDCCH. At 1160, the WTRU may combine the TRP-specific part 1 control information and the TRP-specific part 2 control information. At 1170, the WTRU may detect the PDSCH transmission using the combined TRP part 1 (pDCI) control information and the TRP-specific part 2 (sDCI) control information for all TRPs.

[0160] This article discusses methods for an enhanced transmission configuration indication TCI mechanism for massive distributed MIMO. For massive MIMO, the number of TCIs may be very large (e.g., greater than 128). In addition, for massive distributed MIMO, the number of TRPs may also be very large (e.g., greater than 4). The combination of the two can significantly increase the number of TCI states and code points. These scenarios may increase the overhead in the DCI and / or MAC CE.

[0161] In addition, whether to use DCI or MAC CE may depend on whether it is control or data. For fast indication, MAC CE should be used. For very fast indication, DCI should be used. A unified TCI or a non-uniform TCI can be used. Unified TCI means that a single TCI is applied to both control and data or to DL and UL. Non-uniform TCI uses separate TCIs for control and data, as well as for DL ​​and UL. In non-uniform TCI, there is no mechanism for switching between DCI-based or MAC CE-based. In unified TCI, there is a mechanism for switching between DCI-based or MAC CE-based. This can be done through MAC CE. If MAC CE activates only one TCI state, MAC CE is used to indicate the TCI state for control and data. If MAC CE activates more than one TCI state, DCI is used to indicate the TCI state for control and data.

[0162] Unified TCI can be reused to implement fast indication and very fast indication and switch between the two indications. However, since unified TCI is designed to simplify the TCI method and reduce overhead at the expense of flexibility, flexibility may be lost. In the case of using different beams for control and data, control and data cannot be indicated separately. In order to implement fast indication and very fast indication and switch non-uniform TCI, a solution is needed.

[0163] A solution may be to use the secondary TCI field for TCI indication of PDCCH to achieve fast TCI indication. In addition, the secondary TCI field may also be used to support more TCI states for massive distributed MIMO.

[0164] One solution may be to use DCI to indicate the TCI state for control. For a mini-slot, a first DCI may schedule a first PDSCH and indicate the TCI state for a second DCI or subsequent DCI in the same slot. Similarly, a second DCI may schedule a second PDSCH and indicate the TCI state for a third DCI or subsequent DCI in the same slot.

[0165] For a regular time slot, the first DCI may schedule the first PDSCH transmission and indicate the TCI state for the second DCI or subsequent DCI in the next symbol, time slot, or subsequent symbol or time slot. Similarly, the second DCI may schedule the second PDSCH and indicate the TCI state for the third DCI or subsequent DCI in the next symbol, time slot, or subsequent symbol and time slot.

[0166] In order to indicate the TCI status for control and data respectively, two TCI fields in DCI can be introduced. The first TCI field is mandatory. The second TCI field is optional. The second TCI field can be configured by RRC. If configured, the second TCI field exists, otherwise the second TCI field does not exist.

[0167] When the second TCI field is present, very fast indication and switching can be achieved.DCI can be used to indicate TCI status for control and data respectively.

[0168] Fig.12An example method 1200 for resource allocation utilizing fast TCI indication is shown. At 1210, the WTRU may be configured for a TCI state. At 1220, the WTRU may monitor the PDCCH transmission based on the configuration. At 1230, the WTRU may detect the PDCCH transmission and decode the DCI. If the second TCI field is configured, at 1240, the WTRU may obtain TCI information from the second TCI field in the DCI. At 1245, the WTRU may decode the next PDCCH using the beam indicated in the TCI of the second TCI field. If the second TCI field is not configured, at 1250, the WTRU may obtain TCI from the MAC CE. At 1255, the WTRU may decode the next PDCCH transmission using the beam indicated in the MAC CE. At 1260, the WTRU may obtain TCI from the first TCI field in the DCI. At 1265, the WTRU may detect the current PDSCH transmission using the beam indicated in the TCI of the first TCI field in the DCI.

[0169] Each TCI code point may indicate multiple TCI states. The first TCI field and the second TCI field may indicate a code point containing multiple TCI states. For large-scale distributed MIMO, the first TCI field may indicate a code point containing 16, 32, 64 or more TCI states. Similarly, the second TCI field may indicate a code point containing 16, 32, 64 or more TCI states. The TCI field may be a control field in the control field in the DCI. The TCI field may include a bit that may indicate a TCI code point in the TCI code point. Each TCI code point may contain or point to one or more TCI states.

[0170] Depending on different scenarios and use cases, the first TCI field and the second TCI field may be configured with different bit widths. For example, if a wider beam is used for control and a narrower beam is used for data, the second TCI field may be configured with a smaller bit width than the first TCI field.

[0171] One solution (Solution 1) may be to use another DCI field. Another solution (Solution 2) may be to activate a set of TCI pairs in the MAC CE. Yet another solution (Solution 3) may be to activate a subset of TCI pairs in the MAC CE. In order to adapt TCI based on WTRU mobility and to support high WTRU mobility, fast activation / deactivation of TCI is required. The WTRU may report its mobility (e.g., speed, direction, positioning information, etc.). The TCI scheme may be switched between Scheme 1 and Scheme 3. If the mobility is above the threshold, fast TCI adaptation is required, and Scheme 1 (or Scheme 2) and DCI are used. If the mobility is not above the threshold, slow TCI adaptation is required, and Scheme 3 and DCI are used. The slow TCI adaptation scheme requires 2-stage processing, involving MAC CE working with DCI. The fast TCI adaptation scheme does not require 2-stage processing, and does not involve MAC CE working with DCI. It only requires DCI to change the TCI state, which is much faster than the combined method of MAC CE and DCI. It should be noted that the mobility threshold may be a (pre-)configured speed threshold, a (pre-)configured direction range or a (pre-)configured distance from a reference point.

[0172] Fig.13 An example of beam status before TCI pairing is applied is shown.

[0173] Fig.14 Another solution shown may be to group TRPs in nearby, adjacent or similar directions so that TCI may vary less drastically. For a case where there are 12 TRPs and M1=4 groups (each with M2=3 TRPs), M=M1×M2. 8^M1=8^4 combinations (associations) may be required. This may reduce the overhead by a factor of 3.

[0174] exist Fig.15 In another solution shown, the TRPs may be grouped based on WTRU mobility so that one group contains TCI changes that may not be significant and the other group contains TCI changes that may be significant. Significant TCI changes include situations where a large number of beams need to be changed or updated. Minor TCI changes include situations where only a small number of beams need to be changed or updated. Fig.15In the WTRU, the TCI change rate, beam switching rate, CSI-RS measurement, etc. may be reported for each TRP or TRP group. Based on the report, the TRPs may be regrouped to form new groups, so that in the new TRP group, TRPs with significant TCI changes may belong to the same group, while TRPs with slight or no TCI changes may belong to different groups. For the case where there are 12 TRPs and M1=2 groups (each with M2=6 TRPs), M=M1×M2. 8^M1=8^2 combinations (associations) may be required. This reduces the overhead by a factor of six.

[0175] Fig.16 An example method 1600 for TCI for massive distributed MIMO is shown. At 1610, the WTRU may be configured for a TCI state. At 1620, the WTRU may report a TCI change for a TRP. At 1630, the WTRU may receive a reactivated TCI state via a MAC CE based on the reported TCI state change. At 16340, the WTRU may receive a TCI indication for the reactivated codepoint in the MAC CE. At 1650, the WTRU may receive other control information for all TRPs. At 1660, the WTRU may detect and decode the PDSCH transmission using the beams indicated in the TCI state for all TRPs.

[0176] For the case where the number of TRPs is >> 4, additional multiple TCI fields may be required. In order to allow a unified DCI design to use DCI for fast TCI indication or to support more TCI states using DCI, two TCI fields in the DCI can be used and the other TCI fields can be converted to TCI states in the code points in the MAC CE. In this way, any mode can be configured. For example, a fast TCI indication mode or a secondary TCI state mode for massive distributed MIMO can be configured. If two modes are configured, a one-bit flag can be used to indicate which mode the WTRU should use to operate.

[0177] This article describes a method for dynamic switching between single DCI and multiple DCI for massive distributed MIMO. For multiple TRP scenarios, single DCI and multiple DCI are supported. Whether to use single DCI or multiple DCI can be configured through RRC signaling. Due to the rapid change of channels and the enhanced flexibility of system operation, fast switching between DCI mechanisms is required.

[0178] Fig.17An example method 1700 of DCI mechanism switching is shown. At 1710, the WTRU may report capabilities including resource allocation handling capabilities. At 1720, the WTRU may be configured with more than one DCI mechanism, including a single DCI mechanism and multiple DCI mechanisms. At 1730, resources may be allocated for PDSCH and / or PUSCH to communicate with the TRP.

[0179] If the resource allocations of the TRPs overlap in frequency and time, then at 1740, a single DCI may be activated and enabled (e.g., in a MAC CE). At 1745, the WTRU may decode a single PDCCH from a single TRP. At 1750, the WTRU may obtain a common resource allocation using different TCIs of the TRPs. At 1755, the WTRU may detect a PDSCH transmission using the common resource allocation and different beams indicated by the TCIs of the TRPs.

[0180] If the resource allocations of the TRPs do not overlap, then at 1760, multiple DCI may be activated and enabled (e.g., in a MAC CE). At 1765, the WTRU may decode multiple PDCCHs from multiple TRPs. At 1770, the WTRU may obtain different resource allocations and TCIs for the TRPs. At 1775, the WTRU may detect PDSCH transmissions using separate resource allocations and different beams indicated by the TCIs of the TRPs.

[0181] Both single and multiple DCI schemes may be configured simultaneously, and overlapping resource allocations may be determined and assigned dynamically. Depending on whether the resource allocations overlap, one of the DCI schemes may be activated or enabled. Alternatively, the gNB may determine that overlapping resource allocations will be used and then configure overlapping resource allocations, activating or enabling one of the DCI schemes, such as a single DCI scheme or a multiple DCI scheme.

[0182] This article describes a method for DCI / TCI mechanism adaptation for massive distributed MIMO. The DCI / TCI scheme can be adapted to optimize spectral efficiency, minimize signaling overhead, and achieve system scheduling and operational flexibility. The DCI / TCI scheme can be adapted between multiple DCI / TCI schemes such as a single DCI scheme, a multiple DCI scheme, a hybrid DCI scheme, and a hierarchical DCI scheme. DCI / TCI adaptation can be determined based on specific criteria, including but not limited to transmission type, resource allocation type, and resource overlap type. The transmission type can be coherent or non-coherent joint transmission. The resource allocation type can be overlapping or non-overlapping resources. The resource overlap type can be completely overlapping or partially overlapping.

[0183] Fig.18An example method 1800 of a DCI / TCI scheme adaptation mechanism is shown. At 1805, the WTRU may report capabilities including resource allocation capabilities. At 1810, the WTRU may be configured with multiple DCI schemes. At 1815, resources are allocated for PDSCH transmission of a TRP.

[0184] If it is determined at 1817 that the transmission type is non-coherent joint transmission, then the resource allocation type is further determined at 1819. If it is determined that the resource allocation type is an overlapping type, then the resource overlapping type is further determined at 1821.

[0185] If the resource overlap type is partial overlap, then at 1825 the hybrid DCI scheme is activated and enabled (e.g., in a MAC CE). At 1827, the WTRU may decode the gPDCCH transmission of one TRP from each TRP group. At 1829, the WTRU may obtain a common resource allocation for the TRP group but different TCIs (obtained via gDCI). At 1831, the WTRU may decode gPDCCHs from multiple TRP groups and obtain different TCIs for the TRPs (via gDCI). At 1833, the WTRU may detect PDSCH transmissions using a common resource allocation (CRA) and different beams indicated by the TCI of the TRP (obtained via gDCI).

[0186] If at 1821 the resource overlap type is determined to be a full overlap, then at 1840 the hierarchical DCI scheme is activated and enabled (e.g., in a MAC CE). At 1842, the WTRU may decode the pPDCCH transmission from one TRP. At 1844, the WTRU may obtain the common resource allocation (CRA) but different TCI for the TRP. At 1846, the WTRU may decode the sPDCCH and obtain different TCI for the TRP (via sDCI). At 1848, the WTRU may detect the PDSCH transmission using the CRA (obtained via pDCI) and the beam indicated by the TCI of the TRP (obtained via sDCI).

[0187] If the transmission type is determined to be non-coherent joint transmission (NCJT) at 1817 and the resource allocation type is determined to be non-overlapping type at 1819, then the multi-DCI scheme is activated and enabled at 1851 (e.g., in a MAC CE). At 1853, the WTRU may decode multiple PDCCH transmissions from multiple TRPs. At 1855, the WTRU may obtain different resource allocations and TCIs for the TRPs. At 1857, the WTRU may detect the PDSCH transmission using separate resource allocations and different beams indicated by the TCIs of the TRPs.

[0188] If the transmission type is determined to be coherent joint transmission (CJT) at 1817, then the single DCI scheme is activated and enabled at 1861 (e.g., in a MAC CE). At 1863, the WTRU may decode a single PDCCH from a single TRP. At 1865, the WTRU may obtain a common resource allocation for the TRP but different TCIs (obtained via a single DCI). At 1867, the WTRU may detect a PDSCH transmission using the common resource allocation and different beams indicated by the TCI of the TRP (obtained via a single DCI).

[0189] Fig.19 An example method 1900 for a DCI / TCI adaptation mechanism is shown. The DCI / TCI scheme may be adapted based on the number of DCIs (or PDCCHs) sent, the number of TRPs, and the like. At 1905, the WTRU may be configured with multiple DCI schemes. At 1910, fully overlapping resources may be allocated for PDSCH transmissions (or PUSCHs) of the TRPs. If it is determined at 1915 that several DCIs are to be sent, the number of TRPs is further determined at 1920 and compared to a threshold. If the number of TRPs is greater than a (pre) configured threshold, at 1930, a hierarchical DCI scheme may be activated and enabled (e.g., in a MAC CE). At 1932, the WTRU may decode a pPDCCH from one TRP. At 1934, the WTRU may obtain a common resource allocation for the TRPs. At 1936, the WTRU may decode sPDCCH transmissions from multiple TRPs and obtain different TCIs for the TRPs via sDCI. At 1938, the WTRU may detect the PDSCH transmission using the common resource allocation obtained via pDCI and the different beams indicated by the TCI of the TRP obtained via sDCI.

[0190] If it is determined at 1920 that the number of TRPs is not greater than or less than a (pre-)configured threshold, then the multi-DCI scheme may be activated and enabled (e.g., in a MAC CE) at 1940. At 1942, the WTRU may decode multiple PDCCHs from multiple TRPs. At 1944, the WTRU may obtain different resource allocations and TCIs for the TRPs. At 1946, the WTRU may detect PDSCH transmissions using separate resource allocations and different beams indicated by the TCIs of the TRPs.

[0191] If it is determined at 1915 that several DCIs are not to be sent, and it is determined that only a single DCI is to be sent, then at 1950 a single DCI scheme may be activated and enabled (e.g., in a MAC CE). At 1952, the WTRU may decode a single PDCCH from a single TRP. At 1954, the WTRU may obtain a common resource allocation for the TRP but different TCIs (obtained via a single DCI). At 1956, the WTRU may detect a PDSCH transmission using the common resource allocation and different beams indicated by the TCI of the TRP (obtained via a single DCI).

[0192] In one embodiment, the WTRU may perform hybrid DCI (Hb-DCI) operations and procedures for massive distributed MIMO. In this case, the WTRU may be configured for a hybrid DCI mechanism. The WTRU may be configured with a CORESET and / or CORESET pool for hybrid DCI. Such configuration may be for a TRP group.

[0193] The WTRU may be configured to perform at least one of the following: monitor the group PDCCH or gPDCCH in the search space of the CORESET associated with each TRP group to obtain the group DCI or gDCI; decode the group PDCCH or gPDCCH for each TRP group and all TRP groups accordingly; obtain the TRP group common resource allocation for the TRP group but different TCI (obtained via gDCI); decode the gPDCCH from multiple TRP groups and obtain the TCI information of the TRP (via gDCI); combine all gDCI decoded in the gPDCCH to obtain control information for all TRPs; detect PDSCH transmissions using the group common resource allocation (GCRA) and different beams indicated by the TCI status of the TRP (obtained via gDCI); use the combined obtained control information and TCI information of all TRPs to decode and demodulate the PDSCH transmission from the TRP, or use the combined obtained control information and TCI information of all TRPs to send a PUSCH transmission to the TRP.

[0194] In another embodiment, the WTRU may be configured to perform Hierarchical DCI (Hi-DCI) operations and procedures for massive distributed MIMO.

[0195] The WTRU may be configured to perform at least one of the following: decoding a primary PDCCH or pPDCCH transmission from one of a plurality of TRPs; obtaining control information for common resource allocation (CRA) information for the TRP; obtaining control information for group common resource allocation (GCRA) information for the TRP if the hierarchical hybrid DCI (HH-DCI) scheme is enabled; obtaining different TCI states of the TRP in gDCI / g-gDCI or sDCI information; decoding a secondary PDCCH or sPDCCH; obtaining different TCI state information of the TRP (via sDCI) if TCI information is not carried in the pDCI or G-pDCI; detecting a PDSCH transmission or sending a PUSCH transmission using the CRA indicated in the primary downlink control information (pDCI) or the GCRA indicated in the group pDCI (G-pDCI) and the beam indicated by the TCI state information of the TRP in the pDCI, G-pDCI or sDCI.

[0196] In another exemplary embodiment, the WTRU may perform an adaptation mechanism for the operation and process of multiple DCI / TCI schemes for massive distributed MIMO. The DCI / TCI schemes may be adapted to optimize spectral efficiency, minimize signaling overhead, and achieve scheduling and operational flexibility of the system. The DCI / TCI schemes may be adapted between multiple DCI / TCI schemes such as a single DCI scheme, a multiple DCI scheme, a hybrid DCI scheme, and a hierarchical DCI scheme. DCI / TCI adaptation may be determined based on specific criteria, including but not limited to transmission type, resource allocation type, and resource overlap type. The transmission type may be coherent or non-coherent joint transmission. The resource allocation type may be overlapping or non-overlapping resources. The resource overlap type may be fully overlapping or partially overlapping.

[0197] The WTRU may be configured with multiple DCI schemes. Allocate resources for PDSCH transmission of a TRP. More specifically, the WTRU may be configured to perform at least one of the following: report capability information including resource allocation capability information; if the transmission type is determined to be a non-coherent joint transmission, further determine the resource allocation type; if the resource allocation type is determined to be an overlapping type, further determine the resource overlap type; if the determined resource overlap type is a partial overlap, then (for example, in a MAC CE) activate and enable the hybrid DCI scheme; decode the gPDCCH of one TRP from each TRP group; obtain a common resource allocation for the TRP group but different TCIs (obtained via gDCI); decode gPDCCHs from multiple TRP groups and obtain different TCIs for the TRPs (in gDCI); detect PDSCH using a common resource allocation (CRA) and different beams indicated by the TCI of the TRP (obtained via gDCI); if the resource overlap type is determined to be a full overlap, then (for example, in a MAC CE) activates and enables a hierarchical DCI scheme; decodes a pPDCCH from one TRP; obtains a common resource allocation (CRA) but a different TCI for the TRP; decodes an sPDCCH and obtains a different TCI for the TRP (via sDCI); uses the CRA (obtained via pDCI) and the beam indicated by the TCI of the TRP (obtained via sDCI) to detect a PDSCH or transmit a PUSCH; if the transmission type is determined to be a non-coherent joint transmission (NCJT) and the resource allocation type is determined to be a non-overlapping type, then (for example, in a MAC CE) activates and enables a multi-DCI scheme; decodes multiple PDCCH transmissions from multiple TRPs; obtains different resource allocations and TCIs for the TRPs; detects a PDSCH transmission or transmits a PUSCH using separate resource allocations and different beams indicated by the TCI of the TRP; if the transmission type is determined to be a coherent joint transmission (CJT), then (for example, in a MAC CE) activates and enables a single DCI scheme; decodes a single PDCCH transmission from a single TRP; obtains common resource allocation for the TRP but different TCI (obtained via a single DCI); and / or detects PDSCH using common resource allocation and different beams indicated by the TCI of the TRP (obtained via a single DCI).

[0198] In another exemplary embodiment, the WTRU may perform an adaptation mechanism for the operation and procedures of multiple DCI schemes for massive distributed MIMO. The DCI / TCI scheme may be adapted based on the DCI (or PDCCH) to be transmitted, the number of TRPs, etc. The WTRU may be configured with multiple DCI schemes. Fully overlapping resources may be allocated for PDSCH transmissions (or PUSCH) of TRPs. The WTRU may also be configured to perform at least any one of the following: if it is determined that several DCIs are to be sent, further determine the number of TRPs; if the determined number of TRPs is greater than a (pre-)configured threshold, activate and enable the hierarchical DCI scheme (e.g., in a MAC CE); decode a pPDCCH transmission from one TRP; obtain a common resource allocation for the TRP in the pDCI; decode sPDCCH transmissions from multiple TRPs and obtain different TCIs for the TRPs in the sDCI; detect PDSCH or transmit PUSCH using the common resource allocation obtained via the pDCI and different beams indicated by the TCIs for the TRPs in the sDCI; if the determined number of TRPs is not greater than or less than a (pre-)configured threshold, activate and enable the hierarchical DCI scheme (e.g., in a MAC CE); CE) activates and enables a multi-DCI scheme; decodes multiple PDCCHs from multiple TRPs; obtains different resource allocations and TCIs of TRPs in multiple DCIs carried in multiple PDCCHs; uses separate resource allocations and different beams indicated by the TCIs of TRPs in multiple DCIs to detect PDSCH transmissions or send PUSCH transmissions; if it is determined that several DCIs are not to be sent, and it is determined that only a single DCI is to be sent, then (for example, in a MAC CE) activates and enables a single-DCI scheme; decodes a single PDCCH transmission from a single TRP; obtains different resource allocations and TCIs of TRPs in a single DCI carried in a single PDCCH transmission; and / or uses separate resource allocations and different beams indicated by the TCIs of TRPs in a single DCI to detect PDSCH transmissions or send PUSCH transmissions.

[0199] Although features and elements are described above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method, performed by a WTRU, of switching between operations of a plurality of DCI / TCI schemes, the method comprising: communicating WTRU capabilities including resource allocation handling capabilities; Receiving first configuration information for a first DCI / TCI scheme; receiving an allocation of resources for receiving a physical downlink shared channel (PDSCH) transmission from a plurality of transmit reception points (TRPs) using the first DCI / TCI scheme; receiving configuration information for a second DCI / TCI scheme; as well as Switch from the first DCI / TCI scheme to the second DCI / TCI scheme to receive an allocation of resources for receiving PDSCH transmissions from the multiple TRPs. 2 . The method of claim 1 , wherein the first DCI / TCI scheme is a hierarchical DCI / TCI scheme and the second DCI / TCI scheme is a hybrid DCI / TCI scheme.

3. A method according to claim 2, wherein the hierarchical DCI / TCI scheme includes the WTRU: decoding a primary PDCCH (pPDCCH) transmission from one TRP among the multiple TRPs, obtaining a common resource allocation for the TRP among the multiple TRPs, decoding a secondary PDCCH (sPDCCH) transmission and obtaining different TCIs for different TRPs, and detecting PDSCH transmissions using a common resource allocation (CRA) and the beams indicated by the different TCIs for different TRPs among the multiple TRPs.

4. The method of claim 2, wherein the hybrid DCI / TCI scheme comprises the WTRU: decoding a group PDCCH (gPDCCH) transmission from one of the multiple TRPs, obtaining a common resource allocation (CRA) and different TCIs for the TRP group, decoding gPDCCH transmissions from multiple TRP groups and obtaining different TCIs for the TRPs, and detecting PDSCH transmissions using the CRA of each TRP group and different beams indicated by the different TCIs for the TRP group. 5 . The method of claim 1 , wherein the switching from the first DCI / TCI scheme to the second DCI / TCI scheme is based on a MAC CE.

6. The method according to claim 1, further comprising: PUSCH transmission is sent to the TRP using the combined control information and TCI information of all TRPs obtained using the second DCI / TCI. The method of claim 1 , wherein the first DCI / TCI scheme is a multi-DCI / TCI scheme.

8. The method of claim 1, wherein the first DCI / TCI scheme is a single DCI scheme.

9. A wireless transmit / receive unit (WTRU) for operating using multiple DCI / TCI schemes, the WTRU comprising: a transmitter configured to transmit WTRU capabilities including resource allocation handling capabilities; a receiver configured to receive first configuration information for a first DCI / TCI scheme; a processor coupled to the receiver, the processor configured to receive an allocation of resources for receiving physical downlink shared channel (PDSCH) transmissions from a plurality of transmit reception points (TRPs) using the first DCI / TCI scheme; The receiver is further configured to receive configuration information for a second DCI / TCI scheme; and The processor and receiver are further configured to switch from the first DCI / TCI scheme to the second DCI / TCI scheme to receive an allocation of resources for receiving PDSCH transmissions from the multiple TRPs.

10. The WTRU of claim 9, wherein the first DCI / TCI scheme is a hierarchical DCI / TCI scheme and the second DCI / TCI scheme is a hybrid DCI / TCI scheme.

11. A WTRU according to claim 10, wherein the hierarchical DCI / TCI scheme includes the WTRU: decoding a primary PDCCH (pPDCCH) transmission from one TRP among the multiple TRPs, obtaining a common resource allocation for the TRP among the multiple TRPs, decoding a secondary PDCCH (sPDCCH) transmission and obtaining different TCIs for different TRPs, and detecting PDSCH transmissions using a common resource allocation (CRA) and beams indicated by the different TCIs for different TRPs among the multiple TRPs.

12. A WTRU according to claim 10, wherein the hybrid DCI / TCI scheme includes the WTRU: decoding a group PDCCH (gPDCCH) transmission from one TRP among the multiple TRPs, obtaining a common resource allocation (CRA) and different TCIs for the TRP group, decoding gPDCCH transmissions from multiple TRP groups and obtaining different TCIs for the TRPs, and detecting PDSCH transmissions using the CRA of each TRP group and different beams indicated by the different TCIs for the TRP group.

13. The WTRU of claim 9, wherein the processor and receiver are configured to switch from the first DCI / TCI scheme to the second DCI / TCI scheme based on a MAC CE.

14. The WTRU of claim 10, wherein the first DCI / TCI scheme is a multiple DCI / TCI scheme.

15. The WTRU of claim 10, wherein the first DCI / TCI scheme is a single DCI scheme.

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