Efficient Low-Latency CSI Acquisition in Downlink Bursts

Abstract

A method and device are disclosed for a wireless transmit / receive unit (WTRU). The WTRU is configured with information including a DL burst format table that defines multiple downlink (DL) burst formats. The DL burst formats include one or more physical downlink shared channel (PDSCH) time domain resource allocations (TDRAs), one or more sounding reference signal (SRS) resources, and / or channel state information reference signal (CSI-RS) resources associated with the DL burst formats, and the WTRU may receive downlink control information (DCI) having a field indicating a selected DL burst format from the DL burst format table that defines the time domain location of all signals associated with the selected DL burst for the WTRU. The WTRU may then transmit SRS(s), receive CSI-RS(s), and receive one or more PDSCHs using the TDRA, if any, associated with the indicated selected DL burst formats. Additional embodiments are disclosed.

Description

[Background technology]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 409,672, filed September 23, 2022, the contents of which are incorporated herein by reference.

[0002] The performance of future wireless communication systems may rely on timely and accurate channel state information (CSI). However, in the case of downlink (DL) CSI based on sounding reference signals (SRS), the delay between an SRS transmission and a corresponding physical downlink shared channel (PDSCH) may be too long for adequate performance of such future wireless communication systems.

[0003] Dynamically scheduled physical downlink shared channel (PDSCH) transmission and reception may be based on prior SRS and / or CSI-RS, e.g., for CSI acquisition, beam management, and time-frequency (t / f) synchronization. In time-varying channels (e.g., multiple antennas, high frequency, high mobility, etc.), it is advantageous to transmit and receive SRS and / or CSI-RS with t / f as close as possible to the corresponding PDSCH (considering mobile and base station capabilities, etc.). In legacy systems, PDSCH, SRS, and / or CSI-RS can be separately scheduled / triggered by DL control information (DCI), which can be either: That is, (i) PDSCH has more t / f domain flexibility than aperiodic SRS and / or CSI-RS with less DCI overhead but suboptimal SRS and / or CSI-RS t / f allocation, and / or (ii) PDSCH, SRS and / or CSI-RS have similar t / f domain flexibility with higher DCI overhead but better SRS and / or CSI-RS t / f allocation. A solution that allows for "optimal" SRS and / or CSI-RS t / f allocation (with respect to PDSCH) with low DCI overhead is desirable. Summary of the Invention

[0004] Aspects of the present disclosure may describe embodiments for configuring and triggering / activating DL bursts, which may include SRS, CSI-RS, and PDSCH, in an order optimized for timely DL CSI acquisition and low control overhead. According to one aspect, SRS / CSI-RS resources are linked to rows in a PDSCH time-domain resource allocation (TDRA) table and triggered by a TDRA DCI field, e.g., the SRS slot / symbol offset is determined from the PDSCH start time. The frequency allocation for the triggered SRS may be based on the PDSCH frequency-domain resource allocation (FDRA) of the FDRA DCI field.

[0005] The BS may need to adjust its PDSCH transmission upon receiving the SRS triggered by the first DCI. The subsequent second DCI may adjust the information of the first DCI, for example, adjusting the PDSCH MCS, rank, and t / f resource allocation. The second DCI may be in a second PDCCH (e.g., without blind decoding) or may be multiplexed in the PDSCH. The CSI-RS for tracking (TRS) is enhanced to support P3 beam management (UE Rx beam sweeping). As described herein, a user equipment (UE) may be interchangeably referred to as a wireless transmit receive unit (WTRU).

[0006] Embodiments include an electronic device having a WTRU, the WTRU being configurable by a network with one or more SRS resources, one or more CSI-RS resources, and one or more time-domain resource allocations (TDRAs) for one or more PDSCHs.

[0007] The performance of future wireless communication systems may rely on timely and accurate Channel State Information (CSI). In the case of Downlink (DL) CSI based on Sounding Reference Signal (SRS), the delay between SRS transmission and the corresponding Physical Downlink Shared Channel (PDSCH) must be kept as low as possible. Aspects of the present disclosure propose a method to configure and trigger / activate a Downlink (DL) burst, which may include Sounding Reference Signal (SRS), Channel State Information Reference Signal (CSI-RS), and Physical Downlink Shared Channel (PDSCH) in a configured order for timely DL CSI acquisition and low control overhead.

[0008] Features of the systems described herein include 3GPP Target Feature and Release, Advanced MIMO, MIMO revolution, massively distributed MIMO (MD-MIMO), ultra-massive MIMO (UM-MIMO), cell-free MIMO (CF-MIMO), L1, and L2 / 3.

[0009] The procedures and functions described herein include scheduling, link adaptation, physical downlink shared channel (PDSCH) resource allocation, physical sidelink control channel (PDCCH), and sounding reference signal (SRS).

[0010] Embodiments described herein include a WTRU configured with multiple DL burst formats including SRS, CSI-RS, and one or more PDSCHs (physical downlink shared channels) for downlink (DL) CSI acquisition, where the DL burst formats are indicated in DCI downlink control information, e.g., via a PDSCH TDRA field or via a new field, e.g., a DL burst format indicator, where the DL burst formats include one or more PDSCHs (physical downlink shared channels) Time Domain Resource Allocations (TDRA), where the DL burst formats can include SRS / CSI-RS locations at times configured for the PDSCH TDRA, and where the DCI is split into a first DCI and a second DCI, where the first DCI triggers the DL burst format and the second DCI indicates / adjusts PDSCH parameters based on SRS measurements. The second DCI may be received on the PDCCH without blind decoding or may be multiplexed on the PDSCH. The first and second DCIs may be in different bandwidth parts (BWPs). The frequency domain resource allocation (FDRA) of the SRS for DL ​​downlink CSI may be based on the PDSCH FDRA, and the repetition-enhanced TRS may facilitate both tracking and beam management with the same RS. A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate similar elements and in which: [Brief explanation of the drawings]

[0011] [Figure 1A] FIG. 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communication system illustrated in FIG. 1A according to an embodiment. [Figure 1C] 1B is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system illustrated in FIG. 1A according to an embodiment. [Figure 1D] 1B is a system diagram illustrating another example RAN and another example CN that may be used within the communication system illustrated in FIG. 1A according to an embodiment. [Figure 2] FIG. 1 is a diagram of an aperiodic SRS triggering timeline according to an embodiment. [Figure 3] FIG. 1 is a diagram of a DL burst according to an embodiment. [Figure 4] FIG. 10 is a diagram of a DL burst according to another embodiment. [Figure 5] FIG. 10 is a diagram of a DL burst according to yet another embodiment. [Figure 6] FIG. 1 is a diagram of an UL burst according to an embodiment. [Figure 7] FIG. 1 is a flow diagram of a WTRU procedure according to an embodiment. [Figure 8] FIG. 10 is a diagram of a DL burst according to yet another embodiment. [Figure 9] FIG. 1 is a diagram of a first DCI for scheduling DL bursts on multiple carriers according to an embodiment. [Figure 10] FIG. 10 is a diagram of a second DCI triggering SRS transmission according to an embodiment. [Figure 11] 1 is a diagram of a first and second PDCCH according to an embodiment. FIG. [Figure 12] FIG. 10 is a diagram of a second CORESET separated from a first CORESET according to an embodiment. [Figure 13]FIG. 10 is a diagram of multiple rounds of SRS transmission in a DL burst according to an embodiment. [Figure 14] FIG. 10 is a diagram of an SRS sounding bandwidth according to an embodiment. [Figure 15] FIG. 10 is a diagram of partial sounding of an SRS sounding bandwidth according to an embodiment. [Figure 16] FIG. 1 is a diagram of flexible SRS transmission bandwidth according to an embodiment. [Figure 17] FIG. 10 is a diagram of flexible SS transmission bandwidth according to another embodiment. [Figure 18] FIG. 10 is a diagram of SRS starting resource bandwidth (RB) and sounding bandwidth adaptation according to an embodiment. [Figure 19] FIG. 10 is a diagram of a TRS with iterations (for beam management) according to an embodiment. [Figure 20] FIG. 10 is a diagram of a TRS with repetition (for beam management) according to another embodiment. [Figure 21] FIG. 10 is a diagram of a linking configuration between SRS resource sets and TDRA table rows according to an embodiment. [Figure 22] FIG. 10 is a flow diagram of a WTRU procedure according to another embodiment. [Figure 23] FIG. 10 is a flow diagram of a WTRU procedure according to yet another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] 1A 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, broadcasts, etc., to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content by sharing system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as coded multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailed unique word discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0013] 1A, communications 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, although it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of 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 stations (STAs), may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain situations), consumer electronic devices, devices operating in commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as UEs.

[0014] The communications 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 communications 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 NodeB, an eNodeB (eNB), a home NodeB, a home eNodeB, a next generation NodeB such as a gNode B (gNB), a new radio (NR) NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it should be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0015] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, and the like. The base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in the licensed spectrum, the unlicensed spectrum, or a combination of the licensed and unlicensed spectrum. A cell may provide coverage for wireless services for a particular geographic area, which may be relatively fixed or which may change over time. The cell may also be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the 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 transmit and / or receive signals in desired spatial directions.

[0016] 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 communications 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).

[0017] More specifically, as mentioned 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, SC-FDMA, and the like. For example, the base station 114a and the WTRUs 102a, 102b, 102c in the RAN 104 may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using Wideband CDMA (WCDMA). 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).

[0018] 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), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE Advanced (LTE-A) and / or LTE Advanced Pro (LTE-A Pro).

[0019] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using NR.

[0020] 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 jointly implement LTE and NR radio access, e.g., using a 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 sent to and from multiple types of base stations (e.g., eNBs and gNBs).

[0021] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology 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), GSM EDGE (GERAN), and the like.

[0022] 1A may be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. 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 shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106.

[0023] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying Quality of Service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 may provide call control, charging 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 shown in FIG. 1A , it should be understood that the RAN 104 and / or CN 106 may communicate directly or indirectly with other RANs employing 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, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0024] The CN 106 may also serve 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 providing 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 Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) of the TCP / IP Internet protocol suite. The networks 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include other CNs connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0025] Some or all of the WTRUs 102a, 102b, 102c, 102d of the communications 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 over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may employ a cellular-based wireless technology and with a base station 114b that may employ an IEEE 802.11 wireless technology.

[0026] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, 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 should be understood that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0027] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors in conjunction 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), a state machine, and the like. The processor 118 may perform signal coding, 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 a transceiver 120, which may be coupled to a transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it should be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0028] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It should be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0029] 1B as a single element, 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.

[0030] 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 mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate over multiple RATs, such as NR and IEEE 802.11.

[0031] The processor 118 of the WTRU 102 may be coupled to and receive user input data from the speaker / microphone 124, keypad 126, and / or 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, keypad 126, and / or display / touchpad 128. Additionally, the processor 118 may access information from and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random access memory (RAM), 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, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as a server or home computer (not shown).

[0032] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components of the WTRU 102. The power source 134 may be any suitable device for providing power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0033] The processor 118 may also be coupled to a 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 instead of information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0034] The processor 118 may also be coupled to other peripherals 138, which may include one or more software 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 videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors. The sensor may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, a direction sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, and the like.

[0035] The WTRU 102 may include a full-duplex radio, in which case transmission and reception of some or all of the signals (e.g., associated with a particular subframe on both the UL (e.g., for transmission) and DL (e.g., for reception)) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference by hardware (e.g., a choke) or by signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for either transmission and reception of some or all of the signals (e.g., associated with a particular subframe on either the UL (e.g., for transmission) or DL ​​(e.g., for reception)).

[0036] 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As mentioned above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0037] The RAN 104 may include eNode-Bs 160a, 160b, and 160c, although it should be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Thus, the eNode-B 160a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a, for example.

[0038] Each of the eNode-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, scheduling of users in the UL and / or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0039] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. While 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.

[0040] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may function as a control node. For example, the MME 162 may be responsible for authentication of users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, and the like. 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.

[0041] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0042] The SGW 164 may be connected to a PGW 166, which provides the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0043] The CN 106 may facilitate communication 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 communication between the WTRUs 102a, 102b, 102c and traditional landline communication devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may also provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0044] Although the WTRU is depicted in Figures 1A-1D as a wireless terminal, it is contemplated that in some representative embodiments such a terminal may use a wired communication interface (e.g., temporarily or permanently) with the communication network.

[0045] In a representative embodiment, the other network 112 may be a WLAN.

[0046] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic to a STA originating from outside the BSS may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP for delivery to the respective destination. Traffic between STAs within a BSS may be sent through the AP; for example, a source STA may send traffic to the AP, which then delivers the traffic to the destination STA. Traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between (e.g., directly between) a source STA and a destination STA using direct link setup (DLS). In some representative embodiments, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs within or using an IBSS (e.g., all of the STAs) may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad hoc" mode of communication.

[0047] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, an AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically configured width. The primary channel may be the operating channel of the BSS and may be used by STAs to establish a connection with the AP. In some representative embodiments, carrier sense multiple access with collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. In CSMA / CA, STAs (e.g., all STAs), including the AP, may sense the primary channel. If the primary channel is sensed / detected by a particular STA and / or determined to be busy, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0048] High-throughput (HT) STAs may use 40 MHz wide channels for communication, for example, by combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0049] A very high throughput (VHT) STA may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. A 40 MHz and / or 80 MHz channel may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining eight contiguous 20 MHz channels or two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. In the 80+80 configuration, after channel encoding, the data may be passed through a segment parser that may split the data into two streams. Inverse fast Fourier transform (IFFT) processing and time-domain processing are performed separately for each stream. The streams may be mapped to two 80 MHz channels, and the data may be transmitted by the transmitting STA. In the receiver of the receiving STA, the above-described operations for the 80+80 configuration may be reversed, and the combined data may be sent to the medium access control (MAC).

[0050] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah may support meter-type control / machine-type communication (MTC), such as MTC devices within macro coverage areas. MTC devices may have specific capabilities, for example, limited capabilities including support (e.g., support only) of specific and / or limited bandwidths. MTC devices may include batteries with battery life exceeding a threshold (e.g., to maintain very long battery life).

[0051] WLAN systems that may support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that may be designated as a primary channel. The primary channel may have a bandwidth equal to the largest 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 that supports the smallest bandwidth operating mode among all STAs operating in the BSS. In an 802.11ah example, the primary channel may be 1 MHz wide for a STA (e.g., an MTC-type device) that supports 1 MHz mode (e.g., only supports 1 MHz), even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) setting may depend on the condition of the primary channel. If the primary channel is busy, for example, due to a STA (that only supports 1 MHz operating mode) transmitting to the AP, all available frequency bands may be considered busy even though most of the available frequency bands are idle.

[0052] In the United States, the available frequency bands that may be used with 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total available bandwidth for 802.11ah is 6MHz to 26MHz depending on the country code.

[0053] 1D is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As mentioned 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 communicate with the CN 106.

[0054] While the RAN 104 may include gNBs 180a, 180b, and 180c, it should be understood that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNB 180a, 180b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, and 180c. Thus, the gNB 180a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a, for example. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be in the unlicensed spectrum, and the remaining component carriers may be in the licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multipoint (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0055] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the 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 different or scalable lengths (e.g., including different numbers of OFDM symbols and / or lasting for varying absolute time lengths).

[0056] 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 without also accessing other RANs (e.g., eNode-Bs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize 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 unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with a gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as an eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement a DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0057] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users during UL and / or DL, support for network slicing, DC, interworking between NR and E-UTRA, routing of user plane data towards user plane functions (UPFs) 184a, 184b, routing of control plane information towards access and mobility management functions (AMFs) 182a, 182b, and the like. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0058] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While 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.

[0059] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N2 interface and may function as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration realms, terminating non-access stratum (NAS) signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service being utilized by the WTRUs 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, services for MTC access, and the like. 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.

[0060] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 106 via an N11 interface. The SMFs 183a, 183b may also be connected to the UPFs 184a, 184b in the CN 106 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notification, and the like. PDU session types may be IP-based, non-IP-based, Ethernet-based, and the like.

[0061] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an 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 UPFs 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, providing mobility anchors, and the like.

[0062] The CN 106 may facilitate communication with other networks. For example, the CN 106 may include or 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 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 local DNs 185a, 185b via the UPFs 184a, 184b via an N3 interface with the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0063] 1A-1D and the corresponding description thereof, one or more, or all, of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functionality.

[0064] The emulation device may be designed to perform one or more tests of other devices in a lab environment and / or an operator network environment. For example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communications network to test other devices in a communications network. One or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communications network. The emulation device may be directly coupled to another device for testing and / or to perform testing using over-the-air wireless communications.

[0065] The one or more emulation devices may perform one or more functions (including all functions) while not implemented / deployed as part of a wired and / or wireless communications network. For example, the emulation devices may be utilized in test scenarios in a test lab and / or in a non-deployed (e.g., test) wired and / or wireless communications network to perform testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, e.g., one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0066] In MIMO communications, multiple transmitter and receiver antennas are used to improve communication performance, for example, by spatial multiplexing, spatial diversity, and / or beamforming. In wireless networks, multiple transmit and receive antennas may be deployed at a transmit / receive point (TRP). In traditional wireless networks, one TRP is typically used per cell. A TRP typically has multiple antennas. More recently, TRPs with many, even hundreds of, antennas have been deployed to support massive MIMO schemes.

[0067] Another trend is to deploy additional TRPs within a cell. The benefit of such deployment is a reduction in the average distance and path loss between the WTRU and the nearest TRP, which allows for lower transmit power and therefore less interference in the system. Another benefit is improved spatial diversity, which means that there may be several candidate TRPs that can serve the WTRU. If the radio link to the serving TRP is blocked, the WTRU may instead be served by another TRP that does not have a blocked radio link.

[0068] In a distributed MIMO system, antennas are not located in one or a few TRPs. Instead, the antennas are more widely distributed throughout the wireless network. In some definitions, distributed MIMO also includes a small number of TRPs. Distributed MIMO transmission / reception includes, for example, coherent joint transmission (on the DL) and reception (on the UL), non-coherent transmission, and single frequency network (SFN)-based transmission, with distributed antennas or a small number of TRPs.

[0069] A massively distributed MIMO system (also known as distributed massive MIMO) combines the many antennas of a massive MIMO system with distributed antennas in a distributed MIMO system. For example, hundreds of antennas previously co-located at a massive MIMO TRP covering a geographic area are now distributed throughout that area. A subset of antennas may be co-located at the TRP (sometimes called an access point). Massively distributed MIMO deployments promise very high theoretical performance under ideal assumptions. However, implementing these performance improvements in practice presents many challenges, including fronthaul, synchronization, etc.

[0070] A sounding reference signal (SRS) may be transmitted by the WTRU based on SRS configuration, activation, triggering, etc. by the network. The network may receive SRS measurement results and perform measurements, for example, to estimate the uplink (UL) radio channel, to estimate the downlink (DL) channel, to estimate various parameters such as UE (WTRU) Doppler shift or Doppler spread or UE (WTRU) time offset or delay spread, UE (WTRU) angular orientation, UE (WTRU) position, UL beam management, DL beam management, multi-UE (WTRU) pairing for DL ​​or UL multi-user MIMO, etc.

[0071] In some cases, for example, in systems employing time division duplexing (TDD), which use DL / UL transceiver calibration or other methods to make the effective downlink (DL) radio channel, including the DL transmitter hardware, similar or equivalent to the effective UL radio channel, including the UL receiver hardware, an estimate of the downlink (DL) radio channel may be obtained from the estimated UL radio channel. This is often referred to as DL / UL reciprocity, or simply reciprocity.

[0072] Thus, in a reciprocal system, the SRS can be used to obtain DL channel state information on the network side. This is an alternative to estimating DL CSI at the WTRU based on the DL RS, e.g., CSI-RS, SSB, or DMRS, and feeding back quantized or unquantized CSI from the WTRU to the network. The DL CSI is used on the WTRU side to receive DL transmissions, while the DL CSI is used on the network side to appropriately adapt the DL transmissions, e.g., in terms of modulation and coding scheme (MCS), multi-antenna precoding, etc.

[0073] The advantage of SRS-based DL CSI acquisition is that DL CSI is readily available on the network side and can be immediately used to adapt DL transmission, which means that the CSI feedback delay, including the time between DL RS reception and the corresponding CSI feedback transmission, as well as the CSI feedback processing delay in the network, can be avoided.

[0074] SRS-based DL CSI acquisition can also be particularly efficient in massively distributed MIMO systems. For example, consider a simple example with 100 network-side antennas and one WTRU antenna. Therefore, the DL CSI includes 100 radio channels. DL CSI acquisition based on WTRU measurements of DL RSs requires 100 DL RSs to estimate the 100 channels. Also, quantized CSI reports may have to represent the 100 channels. On the other hand, SRS-based DL CSI acquisition only requires a single SRS, which can be received by the 100 antennas and used to estimate all 100 channels by exploiting correlation. This example illustrates the potentially large overhead reduction of using SRS instead of DL RSs during DL CSI acquisition in massively distributed MIMO systems.

[0075] 5G NR SRS can provide a flexible framework for network-controlled WTRU transmission of SRS resources. Several characteristics of the SRS resources can be configured. Some of the characteristics are discussed below.

[0076] The network may provide a spatial reference RS (target RS) for the SRS resource, and the WTRU transmits the target SRS resource using the same spatial domain filter (e.g., UL Tx beam and / or UL Tx panel) as that used to receive the reference RS (e.g., DL Rx beam and / or DL ​​Rx panel).

[0077] The frequency resources spanned by the SRS resources are also configured, as is the frequency hopping pattern, if any. SRS resources may be grouped into an SRS resource set. Several characteristics may be configured for each SRS resource set. SRS resources in an SRS resource set may be periodic, semi-persistent (SP), or aperiodic (AP).

[0078] The periodic SRS resource is configured and then transmitted periodically, and a spatial reference RS may be configured for the periodic SRS resource.

[0079] After a semi-persistent (SP) SRS resource is activated, it is transmitted periodically until it is deactivated. Activation / deactivation is carried in the MAC CE and applies to the SP SRS resource set; that is, all SRS resources in the set are activated / deactivated together. A spatial reference RS may be configured for the SP SRS resource. Additionally, the activation / deactivation MAC CE may update the spatial relationship RS of the SRS resources in the SRS resource set.

[0080] Periodic (AP) SRS resources are transmitted when triggered by downlink control information (DCI) carried on the physical downlink control channel (PDCCH). An AP SRS resource set may be configured with one or more AP SRS resource trigger values. An AP SRS resource set is triggered if the DCI indicates an AP SRS resource trigger value with the field "SRS Request" equal to the configured trigger value for the AP SRS resource set. In other words, a DCI may trigger multiple SRS resource sets.

[0081] The AP SRS resources may be configured with a spatial reference RS. The spatial reference RS for the AP SRS resources in the AP SRS resource set may be updated using the MAC CE.

[0082] A joint transmission configuration indicator (TCI) framework is introduced, in which the spatial reference RS (also called quasi-co-located (QCL) source RS) for all SRS resources in one or more SRS resource sets can be updated using MAC CE or DCI. If the spatial reference RS is to be updated using the new mechanism, the spatial reference RS is configurable per SRS resource set. The joint TCI framework enables joint and simultaneous TCI state updates for various DL signals / channels, such as PDCCH, PDSCH, and CSI-RS, and various UL signals / channels, such as PUCCH, PUSCH, and SRS. In one example, the TCI state of the PDSCH (including the spatial QCL source RS) and the spatial reference RS for one or more SRS resource sets with usage "antenna switching" are jointly and simultaneously updated to the same DL RS. This enables simultaneous beam switching for both the PDSCH and the SRS used for PDSCH CSI acquisition with low overhead.

[0083] 2, an exemplary aperiodic SRS timeline 200 is shown, which can be, and typically is defined as, the minimum time between the last symbol of the PDCCH 205 that triggers the aperiodic SRS 210 and the first symbol of the triggered SRS resource. In one example of an SRS for antenna switching, the minimum time is N2+Tswitch, as shown in FIG. 2, where N2 is given by Table 1 below for two different WTRU processing capabilities, and Tswitch is the UL switching gap between 35 and 210 μs, i.e., approximately ½ to 3 symbols for a 15 kHz subcarrier spacing (numerology μ=0).

[0084] [Table 1]

[0085] CSI-RS is a multipurpose DL RS in 5G NR. CSI-RS is organized as CSI-RS resources and CSI-RS resource sets, which may include one or more CSI-RS resources. Several types of DL CSI resources are defined in NR, such as non-zero power (NZP) CSI-RS resources, zero power (ZP) CSI-RS resources, and CSI interference measurement (IM) resources.

[0086] The NZP CSI-RS resource carries a CSI-RS that includes parameters known by the WTRU, for which the WTRU can perform various signal and channel measurements. Unless otherwise specified, "CSI-RS resource" and "CSI-RS resource set" refer to the NZP CSI-RS resource and the NZP CSI-RS resource set, respectively.

[0087] The ZP CSI-RS resource includes a similar resource element (RE) configuration as the NZP CSI-RS resource, but may not include CSI-RS. The ZP CSI-RS resource may be used for rate matching of the PDSCH.

[0088] The CSI IM resource may include a set of REs on which the WTRU may perform noise and interference measurements.

[0089] The CSI-RS in NR can be used for various purposes such as beam management, mobility, CSI acquisition, and time-frequency tracking.

[0090] The CSI-RS for beam management may correspond to a CSI-RS resource set for which the parameter repetition is configured (e.g., repetition is configured to be "on" or "off").

[0091] A tracking CSI-RS, also called a tracking RS (TRS), is a CSI-RS resource set with several characteristics. A TRS may span one or two adjacent time slots. A WTRU may use a TRS for fine time-frequency tracking. For this purpose, the PDCCH DMRS and PDSCH DMRS may have the TRS as a QCL source RS, e.g., QCL Type A and QCL Type D. QCL Type A means that the WTRU may estimate the Doppler shift, Doppler spread, mean delay, and delay spread from the TRS and apply the estimates to the reception of the PDCCH / PDSCH DMRS. QCL Type D means that the WTRU may estimate spatial Rx parameters, e.g., the Rx beam and / or Rx panel, to be used for PDCCH / PDSCH DMRS reception from the TRS. QCL Type D may be used, for example, in beamformed systems at mm-wave, sub-THz, or THz frequencies. Network operations may transmit different TRSs using different transmit beams, even from different TRPs. Given that different transmit beams or TRPs may result in different propagation paths, the fine time-frequency tracking and spatial Rx parameters may therefore differ between different TRSs received by a WTRU.

[0092] CSI-RS resources generally can be periodic, semi-persistent (SP), or aperiodic (AP). TRS can be periodic or aperiodic. However, aperiodic TRS typically uses a periodic TRS as the QCL source RS, which means that a periodic TRS is typically configured for connected mode WTRUs. Aperiodic TRS may be used to enable timely TRS reception before PDCCH / PDSCH reception instead of periodic TRS transmissions, which have less periodicity.

[0093] The periodic TRS has the synchronization signal / PBCH block (SSB) as the QCL source, type C (for Doppler shift and average delay). The periodic TRS may also be configured with a QCL source RS, which may be an SSB or CSI-RS resource for beam management, type D (for spatial Rx parameters).

[0094] Aperiodic TRS starts at the symbol after the last symbol of the PDCCH that triggered the TRS. In FR1, the minimum delay may be 0 symbols. In FR2, the minimum delay may be given by the WTRU capabilities (e.g., beamSwitchTiming, which may be, for example, 14, 28, or 48 symbols).

[0095] The timeslot offset between the triggering PDCCH and the corresponding aperiodic TRS is configurable (0 timeslots, 1 timeslot, 2 timeslots, ...) and may vary between aperiodic CSI-RS resource sets.

[0096] Support for a single DCI to schedule multiple PDSCHs (or multiple PUSCHs) in the context of extended support up to 71 GHz is introduced. Various relevant aspects of the enhancement are summarized here. A single DCI (format 1_1) can schedule up to 8 PDSCHs. · Different PDSCHs have separate Transport Blocks (TB). Each PDSCH has one TB, or each PDSCH has two TBs. Each PDSCH is restricted to a timeslot. The PDSCH to HARQ timing shown is the timeslot offset between the last PDSCH timeslot and the timeslot carrying the HARQ-ACK information. ·HARQ-ACK information is carried on the same PUCCH resource. The DCI includes one (first) MCS for the first TB that is applied to the first TB of each PDSCH. The DCI includes, if applicable, a second MCS for the second TB to be applied to the second TB of each PDSCH. ·DCI indicates the New Data Indicator (NDI) for each TB of each PDSCH. ·DCI indicates the redundancy version (RV) of each PDSCH TB. The DCI contains one HARQ process number that applies to the first PDSCH. · The HARQ process number is incremented by 1 (modulo) for each subsequent PDSCH. The DCI indicates the rows of the configured Time Domain Resource Allocation (TDRA) table. The TDRA table is extended so that each row indicates multiple PDSCHs, up to eight. Each PDSCH has a separate {Start and Length Indicator Value (SLIV), mapping type, scheduling offset K0}. The number of scheduled PDSCHs is implicitly indicated by the number of valid SLIVs in the TDRA table row indicated by the DCI. The WTRU does not "expect" to be configured with numberOfRepetitions for the TDRA table of DCI format 1_1. However, numberOfRepetitions can be configured for the TDRA table of DCI format 1_2. ·PDSCH can be in consecutive or non-consecutive time slots. If a PDSCH collides with a UL symbol, the PDSCH is dropped. · The DCI contains a single TCI field, which can correspond to one or two TCI states (similar to the Rel-16 multi-TRP enhancement of PDSCH). · One TCI state: The same TCI state applies to each PDSCH. · Two TCI states: Uses Rel-16 rules for association between TCI states and PDSCH.

[0097] 5G NR sidelink control information (SCI) may be divided into first-stage SCI and second-stage SCI, where the first-stage SCI is transmitted on the physical sidelink control channel (PSCCH) and the second-stage SCI is multiplexed on the physical sidelink shared channel (PSSCH).

[0098] The first stage SCI includes scheduling information for the PSSCH, such as time and frequency resource allocation, DMRS pattern, and MCS. It may also include a resource reservation period, which may be useful for sidelink WTRUs for which the PSSCH is not intended. The first stage SCI may also indicate the format of the second stage SCI, as well as a beta offset value for the second stage SCI, which may be used to control the number of modulation symbols (or resource elements) used for the second stage SCI.

[0099] Depending on the format, the second stage SCI may contain various information such as a HARQ process number, a new data indicator (NDI), a redundancy version (RV), a source and destination ID, a cast type indicator, a CSI request, etc.

[0100] The first stage SCI may need to be received by a larger set of WTRUs than the WTRUs for which the PSSCH is targeted. Hence, the PSCCH (including the first stage SCI) may be transmitted in a broadcast manner, e.g., using a wide beam, diversity transmission, multi-TRP transmission, and / or SFN transmission, while the PSSCH (including the second stage SCI) may be transmitted in a narrow beam that targets the intended WTRUs.

[0101] The first release of 5G NR was designed for high flexibility and forward compatibility. A potential drawback of the flexible design is unnecessarily high complexity and latency in the most common use cases. Subsequent 5G NR releases have addressed this by adding configurable operating modes that are significantly less flexible but more efficient.

[0102] With regard to dynamically acquiring CSI based on SRS for a just-arrived DL / UL data burst, existing cellular communication systems such as 4G LTE, LTE-A, and 5G NR allow great flexibility, e.g., with respect to DCI-triggered aperiodic SRS, DCI-triggered aperiodic TRS, and DCI-dynamically scheduled PDSCH / PUSCH. SRS triggering, TRS triggering, and PDSCH / PUSCH scheduling are independent, which allows great flexibility. However, this flexibility may come at the cost of larger DCI payload size, larger DCI overhead, and potentially greater latency.

[0103] In future communication systems and deployment scenarios (e.g., massively distributed MIMO), timely CSI acquisition will often be paramount to communication performance. Therefore, it may be worth sacrificing some flexibility to reduce CSI acquisition latency. In the following, one or more embodiments of techniques for reducing the delay between the SRS used for CSI acquisition and the corresponding first PDSCH or PUSCH to which the acquired CSI is applied are described.

[0104] Similar to the introduction of downlink (DL) or uplink (UL) bursts, state-of-the-art systems may support flexible scheduling, triggering, etc. of various individual signals and / or channels ("signals / channels"), often at the cost of increased signaling overhead and using separate processing timelines for different signals / channels. However, in many cases, the same set of signals / channels may be used repeatedly and in the same order to support DL / UL data transmission.

[0105] For simplicity of presentation, DL-based embodiments are described that may be used for efficient DL data transmission. However, the described embodiments (methods and procedures) may also be applied to UL data transmission (e.g., single-panel UL transmission, simultaneous multi-panel UL transmission, UL bursts, etc.), in which case the PDSCH may be replaced by a PUSCH, and the SRS for DL ​​CSI acquisition (e.g., involving antenna usage switching) may be replaced by an SRS for UL CSI acquisition (e.g., an SRS for codebook-based or non-codebook-based PUSCH operation) and / or an SRS for UL beam management.

[0106] The purpose of the downlink (DL) burst is to allow efficient DL data transmission and low control signaling overhead, for example by allowing a short delay between SRS transmission and PDSCH reception. One or more typical sets of signals / channels, including their relationship in time, designed for a particular WTRU may be configured and used repeatedly.

[0107] A DL burst may be a collection of signals / channels concentrated in time and used for DL ​​data communication. The signals / channels may include DL signals / channels and / or UL signals / channels. These signals / channels may be periodic, semi-persistent, and / or aperiodic (in various combinations). Concentration in time may refer to the transmission / reception of signals / channels within some time period, such as, for example, a few time slots, subframes, radio frames, milliseconds, etc. DL bursts may be periodic, semi-persistent, or aperiodic, for example, based on the characteristics of the signals / channels that comprise the DL burst.

[0108] Reception of a DL burst or a portion thereof may be scheduled by the network, for example, using a DCI in the PDCCH or by a MAC CE in the PDSCH. Reception of a semi-persistent DL burst or a portion thereof may be activated (and deactivated) by the network, for example, using a DCI in the PDCCH or by a MAC CE in the PDSCH. Reception of a periodic DL burst or a portion thereof may be configured by the network, for example, using RRC signaling.

[0109] The various structures, components, and / or timelines of a DL burst or portions thereof are configurable and may be indicated by a DCI (e.g., triggering, scheduling, or activating the DCI) or by a MAC Control Element (CE). A DL burst may include one or more of the following: A first DCI on a first PDCCH, for example for scheduling or activating a DL burst or part of a burst. In some cases, the first DCI may be considered not to be part of a DL burst. One or more SRSs, e.g., for DL ​​CSI acquisition, antenna switching, or beam management. One or more CSI-RS, e.g., for tracking and / or beam management. A second DCI, for example in a second PDCCH or multiplexed in a PDSCH. · One or more PDSCH transmissions. One or more PUCCH transmissions. In some cases, a PUCCH following a PDSCH may not be considered part of a DL burst.

[0110] A burst may have a burst format that may be at least partially configurable. Various exemplary burst formats are illustrated in Figures 3-6.

[0111] Referring to Figure 3, an example diagram of a DL burst 300 is shown including a second DCI carried on a PDCCH 310 and three PDSCH transmissions 312, 314, and 316. Figure 4 shows an example diagram of a DL burst 400 including a second DCI multiplexed on a first PDSCH 410. The advantages / disadvantages of multiplexing a second DCI on a PDSCH (as in Figure 4) compared to transmitting the second DCI on a PDCCH (as shown in Figure 3) are discussed further herein. Figure 5 shows an example diagram of a DL burst 500 including an SRS transmission 515 between the first PDSCH transmission 510 and the second PDSCH transmission 520, as well as a third DCI piggybacked on the second PDSCH 520. Figure 6 shows an example diagram of an UL burst 600 including three PUSCH transmissions 612, 614, and 616.

[0112] The multiple PDSCHs (or PUSCHs) in a DL burst (or UL burst) may carry different or identical transport blocks, depending on the configuration and / or dynamic indication. In some cases, a subset of the PDSCHs (or PUSCHs) may carry the same transport block, while other PDSCHs (or PUSCHs) may carry other transport blocks. In one example involving four PDSCHs in a DL burst, the first pair of PDSCHs carries the first transport block, and the second pair of PDSCHs carries the second transport block. The transport blocks carried by the multiple PDSCHs (or PUSCHs) may be repeated or mapped across multiple PDSCHs (or PUSCHs), similar to, for example, a conventional PUSCH TB that processes across a multi-slot PUSCH in NR.

[0113] 7, an exemplary high-level WTRU procedure 700 is shown. Further details and variations of the various steps are discussed below. One or more signals / channels of a burst may be canceled and not transmitted or received. For example, a DL signal / channel of a burst may be canceled if it collides with a higher priority DL signal / channel, such as SSB, or if it collides with a symbol configured or designated to be a UL symbol. For example, a UL signal / channel may be canceled if it collides with a higher priority UL signal / channel or if it collides with a symbol configured or designated to be a DL symbol.

[0114] Additionally, signals / channels of a non-canceled burst may be rate-matched around other signals / channels that may or may not be part of the burst.

[0115] In some systems, e.g., 5G NR, PDCCH monitoring and / or PDCCH monitoring capabilities (e.g., maximum number of PDCCH blind decodes, maximum number of non-overlapping control channel elements) are defined in a PDCCH monitoring span (or group), which may correspond to a specific time period, such as a number of symbols or slots. Referring to FIG. 8 of DL burst 800, a first DCI 805 may be received within a first PDCCH monitoring span 810, while a second DCI 815 may be received after the first span 810, e.g., in a second span or in a later timeslot. In one example, the second DCI 815 may be multiplexed on a first PDSCH 820 received after the first span 810. In another example, a second DCI (not shown) may be received on a second PDCCH 830 after the first span 810. The WTRU may also monitor other CORESETs and / or search space sets in the first PDCCH monitoring span 810, such as a broadcast PDCCH or a group-common PDCCH.

[0116] If the second DCI is received on a second PDCCH, the second PDCCH may be within the first span 810 or within a subsequent span. Note that even though various examples herein may assume OFDM as an example waveform, the examples are equally applicable to single-carrier waveforms, such as single-carrier FDMA.

[0117] A DL burst may be scheduled by a first DCI carried by a first PDCCH. A semi-persistent DL burst may be activated by the first DCI carried by the first PDCCH. Once the semi-persistent DL burst is activated by the first DCI, the semi-persistent DL burst may be deactivated by another DCI carried by another PDCCH.

[0118] In various embodiments, the first DCI may convey one or more of the following information, for example, by including a corresponding field or by implicit indication in another field or combination of fields: DL burst format indicator DL Burst Indicator ·SRS request CSI-RS indicator Activation / deactivation of semi-persistent SRS Semi-persistent CSI-RS activation / deactivation HARQ-related information for one or more PDSCHs Indication of one or more PUCCH resources. · Resource Allocation (RA) for one or more PDSCHs. Modulation and Coding Scheme (MCS) Antenna port QCL Information Second DCI Information BWP and cell / carrier information and are described in more detail below.

[0119] The DL burst format indicator may indicate one of multiple DL burst formats. The burst format may correspond to the structure of the burst (e.g., which components are included, their relationship in time, etc.). As described further below in connection with configuring, activating, and triggering DL bursts, multiple DL burst formats may be configured.

[0120] The DL burst indicator (or trigger) may indicate that a DL burst is scheduled or activated. Otherwise, the DCI may be used for other purposes, e.g., for legacy operations such as scheduling a single PDSCH, requesting AP SRS, etc.

[0121] The DL burst format indicator and / or DL ​​burst indicator may indicate one or more of the other parameters / fields discussed herein. For example, the DL burst format indicator may convey a TDRA, an SRS request, a CSI-RS indicator, etc.

[0122] The SRS request (or trigger, or indicator) may request the WTRU to transmit SRS resources in a DL burst. This request may also convey various SRS parameters. SRS may be triggered without an explicit SRS request; for example, the SRS request may be part of a DL burst format indicator or a PDSCH time domain resource allocation.

[0123] The CSI-RS indicator (or trigger) may indicate that one or more CSI-RS resources and / or CSI-RS resource sets (e.g., TRS, CSI-RS for beam management, or CSI-RS for CSI acquisition) are included in the DL burst. CSI-RS may be triggered without an explicit CSI-RS trigger, for example, the CSI-RS indicator may be part of the DL burst format indicator or PDSCH time domain resource allocation.

[0124] Furthermore, the first DCI may activate / deactivate an SP SRS or SP CSI-RS that may be part of a DL burst. For example, the first DCI may activate the SP SRS or SP CSI-RS by deactivation after the DL burst, e.g., automatic deactivation after a time instance after the DL burst, or by explicit deactivation in a DCI after the first DCI.

[0125] Furthermore, HARQ-related information corresponding to one or more PDSCH transmissions may be indicated. This may include an indication of the HARQ process number for one or more PDSCH transmissions, for example, by incrementing the HARQ process number for each subsequent PDSCH transmission of the burst. Alternatively, the DCI may include as many HARQ process number fields as there are transport blocks transmitted in the DL burst, which may be less than the number of PDSCH transmissions (e.g., if a transport block is repeated in multiple PDSCH transmissions or if a rule for deriving HARQ process numbers for multiple transport blocks of a DL burst from one HARQ process number in the DCI applies), more than the number of PDSCH transmissions (e.g., if a PDSCH transmission carries multiple transport blocks), or equal to the number of PDSCH transmissions. Alternatively, the HARQ-related information may include a bitmap having a length equal to the number of transport blocks carried in the DL burst, where a first bit value (e.g., "1" or "0") indicates that the DL burst contains a TB for the corresponding HARQ process. In another case, both a number and a bitmap are included. The bitmap may indicate the HARQ process for the PDSCH transmission in the burst, and the number may indicate the HARQ process number for the first PDSCH transmission. Subsequent PDSCH transmissions may use the next (higher or lower) HARQ process number configured in the bitmap, etc. This number may be the HARQ process number or may be an index into the HARQ process numbers configured by the bitmap, e.g., represented by log2[number of PDSCH transmissions] bits.

[0126] The HARQ related information may include, for example, a new data indicator (NDI) and redundancy version (RV) of the TB of the scheduled PDSCH transmission, as in NR Rel-17 discussed above.

[0127] The first DCI may indicate one or more PUCCH resources that may be used for HARQ-ACK feedback from a PDSCH transmission, for example, by one or more PUCCH resource indicators and / or one or more inter-PDSCH HARQ feedback timing indicators.

[0128] Time / Frequency (t / f) Domain Resource Allocation. One or more PDSCH transmissions may be scheduled by the first DCI. The first DCI may indicate, at least in part, a Time Domain Resource Allocation (TDRA) and / or a Frequency Domain Resource Allocation (FDRA). In 5G NR, the TDRA field selects a row (entry) of a configured TDRA table (list). A table row may include one or more PDSCH TDRAs. The PDSCH TDRA may include the time slot offset (k0) between the DCI and the PDSCH, the PDSCH mapping type, the SLIV, and the number of repetitions.

[0129] The TDRA of the DCI of a DL burst may correspond to one or more Start and Length Indicators (SLIVs) for the time domain allocation of the PDSCH (e.g., symbol allocation within a timeslot) and / or the timeslot offset between the DCI and the timeslot containing the PDSCH, similar to 5G NR. The TDRA of the first DCI may be the TDRA of the first PDSCH. The TDRA of the subsequent PDSCH may be in the second DCI (or subsequent DCI).

[0130] When a PDSCH is scheduled / activated by a first DCI, it may be beneficial to be able to adjust the number of PDSCH REs of the second DCI, for example, based on the MCS adjustment of the second DCI or based on the most recent DL buffer condition. Thus, the TDRA of the first DCI may include the starting time slot and symbol of the first PDSCH. The length (e.g., number of symbols and / or number of slots) of the first PDSCH may be included in the second DCI. Alternatively, the second DCI may adjust the reserved length, which is indicated in the first DCI, for example, by the SLIV or by a length offset that may be added to the reserved length.

[0131] Furthermore, the TDRA of the second DCI may include the starting time slot and symbol of the second PDSCH, if any, along with the subsequent DCI and PDSCH. In various examples, the TDRA table is extended to include or be linked to more signals / channels of a DL burst, e.g., for more efficient control signaling. A row of the TDRA table may include or be linked to information about one or more SRSs and / or CSI-RSs in addition to one or more PDSCHs. The TDRA and TDRA fields may be part of the DL burst format indicator, or vice versa. The configuration of the TDRA table (or DL ​​burst format table), etc., is discussed herein.

[0132] Modulation and coding scheme (MCS). The first DCI may convey one or more MCSs for the PDSCH. The one or more MCSs may apply to one, a subset, or all of the PDSCHs of the burst. For example, the DCI indicates one to two MCSs to apply to one to two TBs of each PDSCH of the burst. In another example, the DCI conveys an MCS for each TB of the burst. In some cases, one or more MCSs are partial or spare MCSs, and the second (or subsequent) DCI conveys the remaining partial or adjusted MCS. In some cases, the first DCI also conveys an MCS applicable to the second DCI, which may be the same as or different from the MCS of the corresponding PDSCH.

[0133] Antenna ports. The first DCI may convey PDSCH and PDSCH DMRS antenna ports, including the number of antenna ports. In some cases, the first DCI may indicate PDSCH DMRS antenna ports, and the second DCI may indicate PDSCH antenna ports, which may be, for example, a subset of the PDSCH DMRS antenna ports.

[0134] QCL Information. The first DCI may convey QCL information (including QCL for various time, frequency, and spatial parameters) for various signals / channels of the burst, for example, in the form of one or more TCI fields. The TCI fields correspond to one or more TCI states, which may provide information of the QCL source RS for one or more DL signals / channels and / or one or more UL signals / channels of the burst.

[0135] The QCL information may include one or more spatial source RSs for the SRS of the burst. For example, the spatial source RSs may be applicable to an SRS resource or an SRS resource set. The QCL information may include one or more QCL source RSs for the CSI-RS of the burst. The QCL information may also include QCL information, e.g., QCL source RSs, for one or more PDSCHs. In some cases, one or more CSI-RS resources of a burst may serve as a QCL source for one or more PDSCHs. For example, the TRS of a burst may serve as a QCL source for each PDSCH of the burst. In another example, a CSI-RS for beam management of a burst may serve as a spatial QCL source for one or more PDSCHs of the burst.

[0136] Second DCI Information. In addition to what is discussed above, the first DCI may include information about the second DCI, such as the DCI format, which may include the CRC size, the exact time-frequency location of the second PDCCH, the beta offset (if the DCI is multiplexed with the PDSCH), the presence of the second DCI, etc. The second DCI information may include an indication of a CORESET (e.g., a CORESET ID) and / or a search space set (e.g., a search space set ID) in which the WTRU may expect the second DCI. In some cases, the first DCI may include information about the second DCI, such that a small number of blind decodes may still be required for the second DCI. For example, a small set of time-frequency locations, PDCCH candidate indices, aggregation levels, etc. may be indicated.

[0137] BWP and Cell / Carrier Information. The first DCI may schedule / activate a DL burst for another BWP and / or another serving cell (or carrier). For example, the DCI may include a BWP indicator, and a BWP other than the active BWP (on which the first DCI is received) may indicate switching to the indicated BWP for reception of the burst. The DCI may also include a carrier indicator (or serving cell indicator), which may indicate that the burst is scheduled / activated for another carrier / cell. Referring to Figure 9, an example of a multi-carrier DL burst 900 is shown. In some cases, the first DCI may schedule a DL burst for multiple BWPs and / or serving cells (or carriers).

[0138] 5G NR supports the use of a single DCI to schedule one or more PDSCHs. The single DCI conveys the information necessary to receive one or more PDSCHs. However, in a DL burst, some DCI information may depend on the SRS measurement of the DL burst, e.g., the MCS of the PDSCH. Therefore, control information may be split between the first DCI and subsequent DCIs of a DL burst. While the second DCI is used as an example, similar information may be conveyed by subsequent DCIs, such as the third, fourth, and so on. However, in some cases, a single DCI (the first DCI) schedules / activates a DL burst, and subsequent DCIs are not part of the burst.

[0139] In some embodiments, the second DCI includes the following information: ·MCS information Antenna port ·FDRA QCL Information SRS information Exclusion and Cancellation Indications Subsequent DCI information may include one or more of:

[0140] Conveying MCS information in the second DCI may be appropriate because it may take SRS measurements into account. The MCS may be applicable to one or more PDSCHs. Full MCS information may be carried in the second DCI. Alternatively, a partial or adjusted MCS may be carried in the second DCI.

[0141] For example, the first DCI may convey a range of MCSs, and the second DCI may convey an MCS within that range. For example, the first DCI may convey a modulation scheme (e.g., QPSK, 16-QAM, etc.), and the second DCI may convey a coding rate to use with that modulation scheme. In another example, the first DCI may convey an MCS table, and the second DCI may convey the exact MCS to use within the MCS table. Such division may be beneficial to the WTRU receiver timeline because PDSCH demodulation may be completed before the second DCI is decoded, assuming that the PDSCH demodulation operation can be performed knowing only the modulation scheme obtained after decoding the first DCI. After decoding the second DCI and obtaining the coding rate, the PDSCH may be decoded, for example, based on the demodulated soft bits.

[0142] In another example, the second DCI conveys an MCS offset that can be used to adjust the MCS indicated by the first DCI. For example, a 3-bit MCS offset may adjust the MCS level of the first DCI by −4, −3, −2, −1, 0, +1, +2, or +3. The MCS offset may adjust the MCS level so that it does not fall below the minimum MCS level and does not exceed the maximum level.

[0143] In another example, the second DCI conveys rate-matching parameters to be applied to one or more PDSCHs (e.g., the PDSCH on which the DCI is multiplexed, the next PDSCH, or one or more subsequent PDSCHs). The rate-matching parameters may indicate one or more rate-matching patterns from a configured set of rate-matching patterns. The DCI may also convey to which one or more PDSCH transmissions the rate-matching parameters apply.

[0144] In another example, the second DCI conveys puncturing parameters to be applied to one or more PDSCHs (e.g., the PDSCH on which the DCI is multiplexed, the next PDSCH, or one or more subsequent PDSCHs). The puncturing parameters may indicate one or more puncturing patterns from a configured set of puncturing patterns. The DCI may also convey to which one or more PDSCH transmissions the puncturing parameters apply.

[0145] In some cases, the second DCI may convey a PDSCH DMRS and / or a PDSCH antenna port. If the second DCI is carried on a PDCCH, the second DCI may indicate both a PDSCH DMRS and a PDSCH antenna port, for example, as an indication in 5G NR.

[0146] In another example, the first DCI may indicate the PDSCH DMRS antenna ports, e.g., if the second DCI is multiplexed with a PDSCH or if it is received on another PDCCH. The second DCI may indicate whether the set of PDSCH antenna ports is the same as the PDSCH DMRS antenna ports or whether it is a subset of the PDSCH DMRS antenna ports. For example, the second DCI may result in the network potentially reducing the PDSCH transmission rank later, e.g., due to recent SRS measurements that may indicate channel changes (e.g., significant path disruption) or due to multi-user scheduling.

[0147] A field of one or more bits may indicate to the WTRU whether the transmission rank is reduced. If not, the PDSCH uses the same antenna port as the PDSCH DMRS. In a 1-bit field, rank reduction may mean a rank reduction of only one, or a rank reduction to rank 1. In some cases, the lowest-numbered PDSCH DMRS antenna port may be used for PDSCH reception. Alternatively, the second DCI may indicate a subset of antenna ports for the PDSCH DMRS to be used for the PDSCH. If multiple PDSCH DMRS antenna ports are indicated by the first DCI, the second DCI itself may be received on a specific antenna port, for example, on the PDSCH DMRS antenna port with the lowest index, or on a PDSCH DMRS antenna port also used for the phase tracking RS. Alternatively, the DCI may be duplicated / repeated across multiple PDSCH DMRS antenna ports.

[0148] According to various embodiments, the second DCI may convey FDRA information for one or more PDSCHs. The second DCI may adjust the FDRA indicated in the first DCI or provide a new FDRA that may be independent of the FDRA indicated in the first DCI. For example, the second DCI FDRA may adjust the edge RB (e.g., the starting RB or ending RB) of the first DCI FDRA. The second DCI FDRA may include a positive or negative RB offset that may be added to the edge RB number, thereby increasing or decreasing the PDSCH bandwidth. When the second DCI is multiplexed to a PDSCH and is located at (or near) an edge RB, the second DCI FDRA may adjust the other edge. This may be useful when the FDRA of the PDSCH into which the second DCI is multiplexed is adjusted. When the second DCI FDRA provides a new FDRA, it may be restricted to include the RB carrying the second DCI.

[0149] The WTRU may know in advance, e.g., by configuration, by indication, or by specification rules, the maximum set of RBs that the second DCI (and corresponding PDSCH) can indicate, e.g., the maximum bandwidth or maximum RB offset magnitude, before receiving the second DCI. This may help the WTRU avoid receiving DL signals / channels with an unnecessarily large receiver bandwidth.

[0150] The second DCI may indicate QCL information, e.g., one or more QCL source RSs (and corresponding QCL types) for the DMRS of one or more PDSCHs, or may indicate one or more TCI states for the DMRS of one or more PDSCHs. The QCL information may be in the form of a TCI field. The indicated QCL source RSs may be signals of DL bursts, e.g., SRS resources or CSI-RSs (e.g., TRSs or CSI-RSs for beam management).

[0151] 10, the second DCI 1012 may trigger or cancel a subsequent SRS transmission 1020 of the burst 1000. The second DCI 1012 may activate or deactivate a semi-persistent (SP) SRS. Additionally, the second DCI 1012 may indicate or update the spatial QCL reference RS for the subsequent SRS transmission (e.g., the preceding CSI-RS of the burst), for example, by including a corresponding TCI field in the second DCI 1012.

[0152] The second DCI (or a subsequent DCI) may include a preemption indication for a past or future transmission (e.g., PDSCH, PDCCH, PUSCH, PUCCH, CSI-RS, or TRS), indicating that some resources are being preempted. For past transmissions, the WTRU may assume that the intended signal / channel is not transmitted on the preempted resources, resulting in, for example, PDSCH puncturing. For future transmissions, the WTRU may "assume" that the intended signal / channel is not transmitted on the preempted resources, resulting in, for example, PDSCH puncturing. Furthermore, future DL or UL transmissions may be canceled, e.g., future PDSCH transmissions or future SRS transmissions may be canceled. One difference between preemption and cancellation may be that preemption refers to a set of resources (e.g., RBs and / or symbols), i.e., resources not used for the original transmission, whereas cancellation may refer to the cancellation of a channel or signal transmission.

[0153] The second DCI may include information about subsequent DCIs of the burst, which may be identical or otherwise similar to the information in the first DCI regarding the second DCI, as described above. In some cases, the second DCI is transmitted on a second PDCCH.

[0154] For timely CSI applications, it may be beneficial to reduce the delay between the transmission of the second DCI and the subsequent PDSCH. A large portion of the DCI decoding delay in state-of-the-art systems may be due to the significant blind decoding effort of several different PDCCH candidates with different aggregation levels, DCI formats, etc. To reduce the DCI decoding delay (and simultaneously the WTRU effort, power consumption, etc.), it may be beneficial to reduce the amount of blind decoding required for the second DCI. In some cases, the time-frequency location, aggregation level, DCI format, etc. are known by the WTRU after decoding the first DCI, so that no blind decoding is performed. A drawback may be reduced flexibility in PDCCH transmission. However, this drawback may be minor because the flexibility of the first PDCCH may be maintained.

[0155] In various examples, the second PDCCH is received in the same CORESET as the first PDCCH. This can have various implications, such as the QCL source, CORESET frequency resource, CORESET duration, CORESET pool index, etc. being the same for the second and first PDCCHs. The first PDCCH can be received in a first search space set associated with the CORESET. The second PDCCH can be received in a second search space set associated with the same CORESET or linked to the first search space set. In some cases, some time-domain characteristics of the second search space set, such as periodicity, time slot offset, or symbols within a time slot, can be configured as part of the DL burst configuration. The second search space set can be aperiodic and can be triggered upon detection of the first DCI. The second search space set can be semi-persistent and can be activated upon detection of the first DCI.

[0156] In some cases, the first PDCCH carrying the detected first DCI and various parameters of the first DCI, such as A set of resource elements (e.g., control channel element (CCE) indexes, or resource element groups (REGs)), for example, in relation to the first CORESET symbol or in relation to the first symbol of a timeslot. PDCCH candidate index Aggregation Level DCI payload size DCI format DCI CRC size Precoder granularity TCI status PDCCH DMRS scrambling parameters CORESET Pool Index One or more of the following are also used for the second PDCCH and the second DCI.

[0157] In various cases, the DCI format of the second DCI may be different from the DCI format of the first DCI. In some cases, they may be the same. The slot and starting symbol of the second PDCCH may be known to the WTRU after decoding the first DCI. For example, the slot and starting symbol of the second PDCCH may be configured as part of a DL burst format configuration, and the first DCI may indicate the start of the DL burst relative to the time of the first PDCCH. The time offset between the first and second PDCCHs may be a combination or sum of the time offset between the first PDCCH and the DL burst and the time offset of the second PDCCH within the DL burst. The first DCI may also convey scheduling information for the second PDCCH (or an associated CORESET and / or search space set), which may include a time offset value and / or a frequency offset value.

[0158] It should be noted that if the PDCCH candidate indices of the first and second PDCCHs are the same, the sets of resource elements (or CCE indices or REGs) may be different, for example, if the two PDCCHs are in different time slots or in different monitoring time spans. An exemplary diagram is shown in Figure 11, where a first DCI is received on a first PDCCH 1110 of a CORESET on the m-th PDCCH candidate of aggregation level L, and a second DCI is received on a second PDCCH 1120 of the same CORESET, also on the m-th PDCCH candidate of aggregation level L, which corresponds to a different set of REs. The first PDCCH / DCI 1110 may require blind decoding within the corresponding CORESET and search space set, as in legacy systems. However, the second PDCCH / DCI 1120 may be directly decoded without the need for blind decoding, since its parameters (e.g., candidate index, aggregation level, etc.) will be given once the first DCI is correctly decoded. Note that Figure 11 does not show any DL burst signals / channels other than the first and second PDCCHs.

[0159] In some cases, a first PDCCH may be received in a first CORESET and a first search space set, and a second PDCCH may be received in a second CORESET.

[0160] The second CORESET may be in the same BWP as the first CORESET, in a different BWP but in the same serving cell as the first CORESET, or in a different serving cell (and therefore also a different BWP) than the first CORESET.

[0161] In some cases, the second PDCCH is received in a second search space set. In some cases, the search space set of the second PDCCH is not configured or defined. The first and second search space sets may be linked through configuration. After decoding the first DCI, the WTRU may determine parameters of the second PDCCH / DCI from the search space set (second search space set) linked to the search space set in which the first DCI was received and the corresponding CORESET (second CORESET).

[0162] In some cases, the second CORESET (eg, its ID) and / or the second search space set (eg, its ID) is configured in a DL burst format that may be included in, for example, a particular BWP or cell configuration.

[0163] If the first and second CORESETs are separate (e.g., configured separately, or one or more of the parameters of the second CORESET may be derived from those of the first CORESET, while other parameters may be fixed), the PDCCH candidate index and aggregation level of the second PDCCH may remain the same as those of the first PDCCH. This may be achieved by having the two CORESETs have at least some identical configurations so that the same PDCCH candidate index and aggregation level are also present in the second CORESET. This is similar to the solution adopted for multi-TRP PDCCH repetition in 5G NR Rel-17, where DCI is repeated in PDCCH candidates across two linked search space sets and CORESETs, except that the second DCI is not a repetition of the first DCI. Furthermore, the location in time of the second PDCCH, e.g., time slot and / or symbol, may not be fixed in time but may depend on information in the first DCI. PDCCH repetitions may occur within time slots within the same BWP.

[0164] An enhancement to the case of the first and second CORESETs is to allow a different number of PDCCH candidates for a particular aggregation level, in particular for fewer candidates in the second CORESET than in the first CORESET. For example, if a first DCI is decoded in PDCCH candidate m1 at aggregation level L in the first CORESET, then a second PDCCH may be received in PDCCH candidate m2 at aggregation level L, where m2 = mod(m1,M2), and M2 is the number of PDCCH candidates at aggregation level L in the second CORESET.

[0165] The frequency domain resource allocation (FDRA) of the second CORESET may be explicitly configured in the CORESET configuration, as in legacy 5G NR. In one example, the FDRA of the second CORESET is indicated at least in part by the first DCI. For example, the CORESET FDRA may be based on the PDSCH FDRA, such that overlap between the CORESET FDRA and the PDSCH FDRA may be achieved. This may be beneficial for various reasons, such as improved channel estimation or reduced receiver bandwidth. For example, if the CORESET bandwidth is less than or equal to the PDSCH bandwidth, the CORESET FDRA may be adjusted to overlap with the PDSCH bandwidth, for example, by setting the lowest CORESET resource block to align with the lowest PDSCH resource block, or by setting the highest CORESET resource block to align with the highest PDSCH resource block, or by setting the center frequency of the CORESET to align with the center frequency of the PDSCH. If the CORESET bandwidth is wider than the PDSCH bandwidth, the configured CORESET FDRA may be used. Alternatively, the configured CORESET starting RB is adjusted to the minimum number that achieves perfect frequency overlap with the scheduled PDSCH.

[0166] FIG. 12 shows an example 1200 in which the second CORESET 1220 is separate from the first CORESET 1210. The WTRU decodes the PDCCH candidate m2 of the second CORESET 1220 (of aggregation level L) because it decoded the first DCI of the PDCCH candidate m1 of the first CORESET 1210 (of aggregation level L) based on the rule / relationship between m1 and m2, e.g., m2 = m1 or m2 = mod(m1, M2). The exemplary diagram also shows the second CORESET 1220 overlapping in frequency with the scheduled PDSCH 1230, which may be achieved by the method described above. The exemplary diagram also shows cross-BWP scheduling of DL bursts. Note that for clarity, FIG. 12 may not show all signals / channels of the DL burst.

[0167] In some cases, the second DCI is multiplexed with the PDSCH (e.g., the first PDSCH) or in one or more subsequent PDSCHs. The various methods described for when the second DCI is transmitted in the second PDCCH may also apply when the second DCI is multiplexed in the PDSCH. The second DCI may be separately encoded, modulated, and multiplexed in the PDSCH, similar to how second-stage sidelink control information (SCI) is multiplexed in the physical sidelink shared channel (PSSCH), as described above. However, the functionality of the second DCI may differ from that of the second-stage SCI. In various embodiments, the second DCI is intended to provide the subsequent PDSCH with the latest control information, such as the latest MCS and antenna port based on the just-measured SRS, and other adjustments to the PDSCH, such as cancellation. The purpose of the first and second stage SCIs includes providing information (such as resource reservation) that is primarily relevant to a number of WTRUs in the first stage SCI, while the second SCI provides information relevant to WTRUs that are intended to receive the PSSCH.

[0168] Furthermore, the encoding, modulation, multiplexing, etc. of the second DCI onto the PDSCH may follow the principles of multiplexing uplink control information (UCI) in the PUSCH of 5G NR, which may be useful, for example, to avoid simultaneous transmission of the PUCCH and the PUSCH.

[0169] In the case of a multi-layer PDSCH, a single-layer DCI may be transmitted on one or more layers, for example, on the lowest-numbered antenna port or on the PDSCH DMRS antenna port also used for the phase tracking RS. Alternatively, the DCI symbol may be duplicated and transmitted on each of the antenna ports. The latter approach is used in 5G NR for control information multiplexing on the shared channel.

[0170] In certain embodiments, it may be advantageous to multiplex the DCI early in the PDSCH, for example, in the first symbol or the first few symbols, to enable DCI decoding completion before PDSCH decoding. Multiplexing the DCI in REs close to the DMRS may also be beneficial for better channel estimation. An advantage of multiplexing the second DCI in the PDSCH rather than a separate PDCCH may be that resource allocation is simpler and more efficient, since separate resources for the PDCCH are not used. Furthermore, multiplexing in the PDSCH may compress the timeline, since the DCI information may be encoded and modulated at the end of the transmit processing pipeline.

[0171] Sounding Reference Signal (SRS) of a DL burst. A DL burst may include a WTRU transmission of one or more SRS resources for CSI acquisition. Depending on various factors such as WTRU mobility, carrier frequency, deployment scenario, etc., the CSI obtained from SRS measurements may be valid for a specific time period (e.g., channel coherence time). If the duration of CSI validity is longer than the DL burst duration, it may be sufficient to transmit one round of SRS in the DL burst, e.g., at the beginning of the DL burst or even before the DL burst. However, if the duration of CSI validity is shorter than the duration of the DL burst, multiple rounds of SRS transmission throughout the DL burst may be required. Furthermore, the CSI obtained from SRS measurements may be valid within a specific bandwidth, e.g., the bandwidth spanned by the SRS, or the coherence bandwidth around the subcarriers carrying the SRS, or the bandwidth spanned by the SRS plus the coherence bandwidth around the edges of the SRS.

[0172] Referring to FIG. 13, a diagram of multiple rounds of SRS transmissions in a DL burst 1300 is shown. A round of SRS transmission may generally correspond to the transmission of one or more SRS resources for CSI acquisition, concentrated in time, e.g., over several symbols or one timeslot. The SRS resources may correspond to one or more SRS resource sets, e.g., SRS resource sets for antenna switching. FIG. 13 shows a DL burst 1300 including two rounds of SRS transmissions 1310, 1320, such that the network can acquire valid CSI for both the first PDSCH 1315 and the second PDSCH 1325. The network-acquired CSI may be reflected in information carried as second and third DCI, e.g., with the MCS indicated for PDSCH 1 1315 and PDSCH 2 1325.

[0173] The location and / or presence of SRS resources in a DL burst may be configured (see below) or indicated, for example, by a MAC CE or a DCI, or a combination. In the case of DCI-triggered SRS, one or more rounds or SRS may be triggered by a first DCI. In some cases, the first round of SRS may be triggered by a first DCI, and further, subsequent rounds of SRS, if any, may be triggered by subsequent DCIs, as illustrated in FIG. 13.

[0174] In some cases, the presence of subsequent rounds of SRS may affect the bundling of PDSCH ACK / NACKs if ACK / NACK bundling is configured. For example, ACK / NACKs corresponding to PDSCH transmissions between two subsequent rounds of SRS may be bundled. If there is only the first round of SRS during a DL burst, all ACK / NACKs in the burst may be bundled. In some cases, ACK / NACKs are bundled based on the set of PDSCHs affected by the second DCI, third DCI, etc. For example, ACK / NACKs from a PDSCH multiplexed with the second DCI may be bundled with ACK / NACKs from a subsequent PDSCH, and then ACK / NACKs from a PDSCH multiplexed with the third DCI may be bundled with ACK / NACKs from the subsequent PDSCH, and so on. Such a scheme may be beneficial because link quality (e.g., error rate, SINR, or SNR) may change between subsequent SRS rounds or subsequent DCIs.

[0175] In some cases, one or more SP SRS resources may be activated by a DCI of a DL burst, for example, the first DCI, or by an Activate MAC CE, or by an RRC message. In some cases, the SP SRS resources may be explicitly deactivated, as in legacy systems. However, this may result in unnecessary overhead because the SP SRS for CSI acquisition may be useful during the DL burst but less useful after the DL burst. Therefore, the SP SRS resources may be automatically deactivated for the duration after the DL burst. For example, the SP SRS resources are deactivated after the last PDSCH transmission of the burst. That is, the first SP SRS resource transmission opportunity after the last PDSCH transmission of the burst is not transmitted. Alternatively, the number of SP SRS resource transmissions (or number of slots) before deactivation may be configured, for example, as part of the DL burst format indicator or as part of the SP SRS resource configuration.

[0176] Flexible SRS Transmission Timing. DCI-based triggering of AP SRS is supported, for example, in 5G NR (as described above in connection with SRS in 5G NR) by an SRS request DCI field having two bits. Since one value ("00") corresponds to no SRS request, up to three different sets of AP SRS resources can be triggered by the DCI in the example. In the example, the time slot offset between the DCI and the time slot of the triggered SRS resource is configurable and not flexible. In addition, in the example, the symbol of the time slot used to transmit the SRS resource is configurable and not flexible. Therefore, primarily due to the limited flexibility of AP SRS, it may be difficult in 5G NR to combine dynamic PDSCH scheduling including variable time slot and symbol offsets with simultaneous triggering of appropriate SRS resources that keeps the latency between SRS and PDSCH low.

[0177] To address this, the SRS offset from the triggering DCI (e.g., the first DCI) or from the second or subsequent DCI may track the offset of the DL burst. If the delay between the DCI and the first PDSCH is short, e.g., two time slots, the first round of SRS may be transmitted with a similarly short delay, e.g., about a time slot after the DCI. On the other hand, if the delay between the first DCI and the first PDSCH is longer, e.g., six time slots, the first round of SRS may be transmitted after a similarly long delay, e.g., about five time slots later.

[0178] A similar problem exists for the SP SRS in 5G NR, which also has a configured timeslot offset. A solution may be to make the timeslot offset of the SP SRS dependent on the timeslot offset of the SP PDSCH, for example, to precede the SP SRS transmission by N timeslots or symbols, where N may be fixed (e.g., equal to 1 timeslot or 21 symbols) or configurable.

[0179] Flexible SRS Transmission Bandwidth. The purpose of an SRS transmission within a DL burst is to adjust or improve the DL transmission scheme, e.g., MCS or multi-antenna selection, precoding, or beamforming, of one or more PDSCHs scheduled for some frequency resources. However, in 5G NR, the frequency-domain characteristics of 5G NR SRS resources are often configured and inflexible. This means that it may not be possible to dynamically trigger SRS transmission only for frequency resources that should be used for subsequent PDSCH transmissions except in special cases. Therefore, a wideband SRS may be configured.

[0180] In one embodiment, the SRS transmission in a DL burst may be augmented such that the frequency resources for the SRS may be adjusted or determined based on the FDRA of a subsequent PDSCH, e.g., of an immediately following PDSCH or of a first PDSCH following a time instance, which may occur at a time delay after the start or end of the SRS transmission, where the time delay may be configurable and fixed by the network.

[0181] An SRS resource may span one or more symbols. An SRS resource may be configured to sound a specific sounding bandwidth. There are several ways in which an SRS resource may sound (e.g., transmit) a specific sounding bandwidth. Some examples are as follows: each RB of the sounding bandwidth may be sounded with a single-symbol SRS resource, e.g., as shown in FIG. 14(a); each RB of the sounding bandwidth may be repeatedly sounded with multiple symbols of a multi-symbol SRS resource (with repetition), e.g., as shown in FIG. 14(b); each RB of the sounding bandwidth may be sounded across multiple symbols of a multi-symbol SRS resource, where different symbols sound different sets of RBs (frequency hopping), e.g., as shown in FIG. 14(c); a subset of RBs of the sounding bandwidth may be sounded across multiple symbols of a multi-symbol SRS resource, where different symbols sound different sets of RBs (frequency hopping), e.g., as shown in FIG. 14(c). A subset of the RBs of the sounding bandwidth may be sounded repeatedly over multiple symbols of a multi-symbol SRS resource (partial sounding), e.g., as shown in FIG. 15(a) ; a subset of the RBs of the sounding bandwidth may be sounded repeatedly over multiple symbols of a multi-symbol SRS resource (partial sounding with repetition), e.g., as shown in FIG. 15(b) ; and a subset of the RBs of the sounding bandwidth may be sounded across multiple symbols of a multi-symbol SRS resource, with different symbols sounding different sets of RBs (partial sounding with frequency hopping), e.g., as shown in FIG. 15(c) .

[0182] In some embodiments, transmission of SRS RBs may be omitted. First, consider a scenario in which the scheduled PDSCH FDRA is within the configured SRS sounding bandwidth. In legacy 5G NR operation, SRS resources are transmitted according to their configured sounding bandwidth. This may result in an unnecessarily large SRS transmission bandwidth, especially if the configured SRS bandwidth is significantly larger than the PDSCH bandwidth. SRS transmission in RBs not used for PDSCH may not be conducive to fast adaptation within DL bursts. In one example, the WTRU may omit SRS transmission outside the PDSCH bandwidth, as illustrated in FIG. 16, where (a)-(c) may correspond to the cases illustrated in FIG. 14(a)-(c). The dashed boxes may represent configured but untransmitted SRS symbols / RBs, and the solid boxes represent transmitted SRS symbols / RBs that are within the configured symbols / RBs.

[0183] In a further example, SRS transmission may also be omitted in RBs within the PDSCH bandwidth. The RBs that can be omitted may depend on the channel coherence bandwidth characteristics. For example, SRS transmission may be omitted in one or more RBs at the edge of the PDSCH bandwidth. In another example, SRS transmission may be omitted in one or more RBs within the PDSCH bandwidth, i.e., not at the edge. The number of omitted RBs may be based on the coherence bandwidth. The RB omission pattern (e.g., the number and / or location of omitted RBs, e.g., at each edge) may be configured by the network, configuring the WTRU to do so. In some cases, multiple patterns may be configured by the network, and one of the patterns may be dynamically indicated, e.g., by the DL MAC CE or in a DCI, e.g., in the first DCI or a second or subsequent DCI. SRS RB omission may also be configured and / or indicated as part of the DL burst format configuration and indication.

[0184] Omission of the SRS transmission bandwidth can help save WTRU power, reduce interference, and increase SRS multiplexing capacity. A potential drawback is that the PDSCH (and SRS) FDRA is determined before SRS-based CSI acquisition. This may result in a reduction in the gain from frequency-selective and channel-dependent scheduling. However, preliminary CSI acquisition before the first DCI is not precluded. Furthermore, the gain from frequency-selective scheduling may be smaller in future systems due to, for example, a large number of antennas, wideband resource allocation, or line-of-sight scenarios. Systems with a large number of antennas (e.g., very massive MIMO, holographic MIMO, or massively distributed MIMO) may experience channel hardening, which, given appropriate multi-antenna processing, reduces the fluctuations due to channel fading, as is known. However, the wideband allocation of the PDSCH may reduce the possibility of scheduling the PDSCH only at channel peaks and avoiding deep fades (in frequency).

[0185] Referring to FIG. 17, in partial sounding, the transmitted SRS bandwidth may also be reduced, as illustrated in FIG. 17(a)-(c), which may correspond to the examples of FIG. 15(a)-(c). In partial sounding, the network may use interpolation to estimate the channel for non-sounded RBs. However, if SRS RB omission based on PDSCH FDRA is directly applied to the SRS resources including partial sounding, the transmitted SRS resources may not provide the transmitted RBs for interpolation at the edge RBs of the PDSCH. Thus, in the case of partial sounding SRS, if SRS is not configured for the edge RBs of the PDSCH, the WTRU may transmit several SRS RBs (e.g., one RB) or the entire block in the block next to the configured SRS RB closest in frequency to the edge RB, as illustrated by the gray squares (e.g., one or more RBs) in FIG. 17. In this manner, the SRS transmission bandwidth may be larger than the PDSCH bandwidth but remain smaller than the configured SRS sounding bandwidth.

[0186] The DCI that triggers an SRS resource transmission, e.g., the first DCI, the second DCI, or a subsequent DCI, may indicate whether the transmission should be according to the configured bandwidth or whether the WTRU should adapt the SRS bandwidth to the scheduled PDSCH FDRA (e.g., with a one-bit or multi-bit field, or implicitly via another field such as the PDSCH TDRA field or the DL burst indicator field). The WTRU may be configured per SRS resource or SRS resource set whether the WTRU should apply the frequency adaptation described herein or whether the WTRU should apply the configured sounding bandwidth as in legacy systems.

[0187] In another approach, the WTRU may adjust the starting RB and / or sounding bandwidth of the SRS resource based on the PDSCH FDRA. Upon receiving the SRS trigger and the PDSCH FDRA in a DCI, e.g., in the first DCI, the second DCI, or a subsequent DCI, the WTRU may set the SRS start RB to be the lowest RB of the PDSCH FDRA. However, the valid starting RB of the SRS may have a different granularity than the lowest RB of the PDSCH FDRA. For example, the SRS start RB may be adjusted in steps of four RBs, while the PDSCH FDRA may use a granularity of one RB. In that case, the WTRU may set the SRS start RB to be the highest valid starting RB, e.g., such that the lowest RB of the PDSCH FDRA is within the SRS sounding bandwidth. Alternatively, the SRS start RB may be set to the lowest valid starting RB that is within the PDSCH bandwidth.

[0188] The WTRU may also set the sounding bandwidth of the triggered SRS resource to be equal to the bandwidth of the PDSCH. The sounding bandwidth granularity may differ from the PDSCH bandwidth granularity. Referring to Figure 18, to address such cases, for example, the sounding bandwidth may be set to the smallest effective sounding bandwidth equal to or greater than the PDSCH bandwidth as shown. Alternatively, the sounding bandwidth may be set to the largest effective sounding bandwidth equal to or less than the PDSCH bandwidth. As yet another alternative, the sounding bandwidth may be set to the smallest effective sounding bandwidth that provides the greatest overlap between the SRS bandwidth and the PDSCH bandwidth.

[0189] The WTRU may be configured with a specific maximum SRS transmission bandwidth per SRS symbol. To increase the sounding bandwidth beyond that maximum bandwidth, the WTRU may add frequency hops in other symbols. The WTRU may be configured with the maximum number of SRS symbols of SRS resources that the WTRU may use for additional frequency hops. For example, if the sounding bandwidth cannot be extended to cover the PDSCH bandwidth even with additional hops due to a limited number of symbols or limited WTRU SRS transmission bandwidth, which may be due to limited UL transmission bandwidth or limited UL transmit power, the WTRU may separate the hops in frequency so that the sounding bandwidth covers the PDSCH bandwidth with partial sounding.

[0190] In some cases, the WTRU may not adapt the SRS sounding bandwidth based on the PDSCH FDRA and may instead use the configured SRS sounding bandwidth. This means that the PDSCH bandwidth may be larger than the SRS sounding bandwidth. In such cases, it may be beneficial for CSI accuracy to have the WTRU transmit an SRS sounding bandwidth near the center of the PDSCH bandwidth. In other words, the WTRU may select the lowest valid SRS start RB such that the difference between the number of PDSCH RBs below the SRS sounding bandwidth and the number of PDSCH RBs above the SRS sounding bandwidth is reduced.

[0191] In the case of SRS resource sets with more Rx antennas than Tx antennas, the WTRU may transmit multiple SRS resources from different sets of antennas in different symbols, and the above method may be applied to each of these SRS resources, as it may be beneficial to sound the bandwidth to be used for the PDSCH of all Rx antennas.

[0192] A DL burst may include various types of CSI-RS resources and CSI-RS resource sets. For example, a DL burst may include one or more TRSs to assist the receiver and demodulation operations of the PDCCH and / or PDSCH of the burst.

[0193] In some cases, a DL burst may include CSI-RS for beam management, e.g., a CSI-RS resource set configured with repetition "on" or a CSI-RS resource set configured with the parameter "repetition." Such a CSI-RS resource set may be used by the WTRU to adjust its DL Rx beam, which may be useful, for example, if the network is adjusting its DL Tx beam / precoder based on SRS-based measurements.

[0194] The TRS and CSI-RS for beam management may be very similar. Both signal structures are based on repetition, with the TRS allowing the WTRU to estimate Doppler-related parameters and the CSI-RS for beam management allowing the WTRU to try different DL Rx beams. A TRS, such as an aperiodic (AP) TRS, may be unsuitable for DL ​​Rx beam sweeping because the WTRU may need to keep its Rx beam fixed during the TRS symbol to properly estimate tracking parameters. Furthermore, L1 measurement reports, such as L1 reference signal received power (RSRP), may not be supported for the TRS. If a TRS is immediately followed by a single-port CSI-RS for beam management, the WTRU may not be able to assume that the same antenna port is used for the TRS and CSI-RS, even if they are QCL.

[0195] Referring to the resource diagram 1900 of FIG. 19, for more efficient resource utilization, the TRS for beam management and the CSI-RS may be combined into one structure (e.g., referred to as TRS with beam management). This combination may be based on a one- to two-timeslot TRS structure 1910, but adding a level of repetition (e.g., two extra repetitions 1912) following the legacy TRS 1910. The same RS value as the legacy TRS 1910 may be repeated for subsequent symbols. The TRS repetitions 1912 may be added over the entire (legacy) TRS bandwidth or only a portion of the TRS bandwidth, for example, within the PDSCH bandwidth of the subsequent PDSCH, or within the bandwidth spanned by all PDSCH transmissions of a DL burst, or within a configurable bandwidth. The portion of the bandwidth of the TRS 1910 may be centered or edge-aligned with the subsequent PDSCH of a DL burst. The repetitions 1920 may share antenna ports with the legacy CSI-RS resources of the TRS.

[0196] In a particular embodiment, the presence of TRS repetition may be indicated to the WTRU in a DCI (e.g., in the first DCI, the second DCI, or a subsequent DCI). If repetition is not indicated, the WTRU may expect a legacy TRS without repetition.

[0197] In one example, a TRS with repetition may be configured by including additional CSI-RS resources of the legacy TRS (e.g., a CSI-RS resource set with the optional parameter trs-Info configured, or a CSI-RS resource set with trs-Info and the additional parameter trsRepetition). The additional CSI-RS resources in the set may have the same configuration as the legacy TRS resources (e.g., single-port and within the same subcarrier), except for the symbol index, which may be different. In some cases, a CSI-RS resource set including a TRS with repetition may be configured with the optional parameter repetition set to "on."

[0198] In another example, the additional CSI-RS resources may not be explicitly configured. Instead, a new optional parameter, e.g., repetitionNumber, may be set for the CSI-RS resource set configured in trs-Info. This parameter may, for example, take the values ​​1, 2, or 3 to indicate the number of repetitions in subsequent symbols after the explicitly configured CSI-RS resource, or 2, 3, or 4 to indicate the total number of repetitions. The example of Figure 19 can be realized, for example, with repetitionNumber=2 in the former example and repetitionNumber=3 in the latter example.

[0199] Referring to FIG. 20 , in another variation, only one or a subset of the legacy TRS CSI-RS resources 2010 may be followed by repetition 2012. As in the previous example, repetition 2012 may be achieved by configuring additional CSI-RS resources for the CSI-RS resource set. Alternatively, and also as in the previous example, the resource set may be configured with the optional repetitionNumber parameter. In this case, a larger repetition number may be set if, for example, the repetition occurs after the second CSI-RS resource in a timeslot or in other previously unused TRS symbols in a timeslot. Furthermore, which of the two or four CSI-RS resources of the legacy TRS the repetition occurs after may be configurable, for example, by the optional parameter repetitionResource, which may be 0, 1, 2, or 3, for example, indicating the first, second, third, or fourth resource of the TRS. Alternatively, the repetition resource is fixed, for example, to the last one. The pattern of Figure 20 may be achieved, for example, by setting repetitionNumber=4 (if additional transmissions are counted) or repetitionNumber=5 (if the total number of subsequent transmissions is counted). The exemplary parameter repetitionResource may be set to 3 in the example illustrated in Figure 20, since the repetition occurs after the last symbol. Note that the DL burst (format) may not include CSI-RS.

[0200] Different WTRUs may have different capabilities, for example, with respect to processing timelines. Prior to configuring and using a DL burst, the WTRU may report its relevant capabilities to the network. These capabilities may include one or more of the following: ·Minimum time between PDCCH and SRS triggered by PDCCH. ·Minimum time between PDCCH and AP CSI-RS triggered by PDCCH. ·Minimum time between CSI-RS and PDSCH, for example when CSI-RS is QCL source RS for PDSCH DMRS. CSI-RS can be TRS, CSI-RS for beam management, TRS with beam management, etc. The minimum time may be different for different QCL types and may be different for different frequency ranges, e.g. the minimum time may be 0 for FR1. · The minimum time between a PDCCH (without blind decoding) and the corresponding PDSCH, for example the second or subsequent PDCCH. The minimum time between the DCI multiplexed in the PDSCH and the RS triggered by the DCI. This time may be different for different RSs, e.g., SRS or CSI-RS. PDSCH processing timeline when DCI is multiplexed in the PDSCH, for example when the DCI contains various information relevant to PDSCH reception and / or decoding, such as MCS.

[0201] DL bursts can be configured, activated, and / or triggered. The network may configure a WTRU with a DL burst configuration, which may include one or more DL burst formats. The DL burst configuration may also include various other configuration parameters, some of which are mentioned above. The DL burst format may be based on WTRU capabilities, e.g., it may not violate a minimum timeline reported by the WTRU. The network may also take WTRU traffic (which may include QoS requirements) and mobility into account when configuring DL bursts, as well as considerations such as scheduling and system efficiency. Thus, the network may configure different WTRUs with different DL burst formats due to, e.g., different WTRU processing capabilities, traffic, and mobility.

[0202] The DL burst configuration may be configured per DL BWP or per serving cell.

[0203] Configuration of the TDRA table for scheduling multiple PDSCHs containing a single DCI may be supported. This feature may be a building block for DL ​​burst format configuration.

[0204] Separate configurations of aperiodic and semi-persistent SRS resources and SRS resource sets, which may be identified by IDs, may also be supported. Aperiodic SRS resources have configurable slot offsets and symbol allocations.

[0205] Similarly, different types of CSI-RS resources and CSI-RS resource sets may also be configured and identified through IDs.

[0206] One way to configure a DL burst format is to associate zero, one, or more SRS resources or SRS resource sets with rows of a configured PDSCH TDRA table (e.g., as described above). Because one row of the PDSCH TDRA table corresponds to one or more PDSCHs, each including an individual timeslot offset associated with a scheduling DCI (e.g., a first DCI, or a second DCI, or a subsequent DCI) and a symbol allocation within that timeslot, the network may also configure a set of SRS resources and their time offsets for the row that includes timing appropriate for the number of PDSCHs.

[0207] This may be achieved, for example, by configuring a list of PDSCH TDRA table row indexes for SRS resources or SRS resource sets (e.g., AP or SP SRS). When a particular PDSCH TDRA table row index (e.g., index i) is indicated in a DCI (e.g., the first DCI, the second DCI, or a subsequent DCI), each SRS resource set having that particular TDRA table row index (e.g., i) configured in that list is triggered / activated by the DCI. An SRS resource for which the list is not configured or for which the list is empty will not be triggered / activated by any TDRA index in the DCI (although it may be triggered by legacy methods, such as a specific SRS request value, if available).

[0208] An alternative approach to linking a PDSCH TDRA table row with one or more SRS resource sets (or resources) is to configure a list of SRS resource set IDs (or resource IDs) in the configuration of the TDRA table row.

[0209] FIG. 21 shows an example diagram of linking 2100 between aperiodic SRS resource sets 2110, 2112, 2114, 2116 and rows of an eight-row TDRA table 2125. Rows 2-7 may correspond to DL bursts because a TDRA table row index between 2 and 7 schedules / activates both PDSCHs according to the TDRA and the corresponding SRS resource sets 2112, 2114, 2116 based on the link between the AP's SRS resource set and the TDRA row index. In this example, since rows 0 and 1 are not linked with SRS resources, an indication in row 0 or 1 may correspond only to a PDSCH TDRA. However, the AP SRS may be triggered by the legacy SRS request field (if present) in TDRA row 0 or 1. This example also shows that AP SRS resource set 0 2110 does not have a TDRA row parameter configured, meaning it is not linked to (and therefore not triggered by) some TDRA table row index.

[0210] In an alternative or complementary approach, the MAC CE may be used to associate one or more SRS resources or SRS resource sets with a TDRA row index. Associating a new set of SRSs with a TDRA row index may clear one or more SRSs previously associated with the index. Note that the above method may eliminate the need for an SRS request field in the DCI and may not increase the number of bits for indicating the TDRA table row, which may simultaneously significantly increase the possibility of improving / adapting SRS transmissions for dynamically scheduled TDRAs of one or more PDSCHs.

[0211] Referring to FIG. 22, an example method 2200 for a WTRU is shown. In a first step, the WTRU may be configured with an SRS resource set (e.g., AP or SP SRS) and a PDSCH TDRA table (2205). One or more SRS resource sets may be configured to be linked with one or more TDRA table rows according to the previous example of FIG. 21. In a second step, the WTRU may decode a first DCI (2210), which schedules a PDSCH (e.g., DCI format 1_0, 1_1, 1_2, or a new DCI format) and includes a TDRA field indicating the TDRA table row. In a third step, the WTRU may determine (2215) whether any SRS resource set is linked with the indicated TDRA table row. If so, in a fourth step, the linked SRS resource set is triggered / activated (2220) and may therefore be transmitted by the WTRU. In addition to transmitting one or more linked SRSs, the WTRU may follow legacy procedures. The WTRU may receive a scheduled PDSCH. If an SRS resource set was not linked with the indicated TDRA table row (2215), in a fifth step the WTRU may follow legacy procedures (2225) and receive a scheduled PDSCH accordingly.

[0212] Referring to FIG. 23 , in the example method 2300, an SP SRS resource set may be linked to a TDRA table row 2305. If a first DCI activates one or more SP PDSCHs by indicating a row in the TDRA table, the linked SP SRS resource set may be activated as well. A TDRA table row may be linked to both an AP SRS resource set and an SP SRS resource set. To address such cases, in a first step, the WTRU may be configured with linkages between one or more AP SRS resource sets and one or more rows in the PDSCH table, and linkages between one or more SP SRS resource sets and one or more rows in the PDSCH table 2305. In a second step, the WTRU may decode 2310 the first DCI, which schedules a PDSCH (e.g., DCI format 1_0, 1_1, 1_2, or a new DCI format) and includes a TDRA field indicating a TDRA table row. In a third step, the WTRU may determine 2315 whether the DCI activates an SP PDSCH. If so, in step 4, the WTRU may determine 2320 whether there are any SP resource sets linked to the indicated TDRA row. If so, in step 6, the WTRU may transmit 2325 the linked SP SRS resource set, for example, after activating the SP SRS resource set or after interpreting the indicated TDRA row as an SP SRS resource set activation command. If the SP resource set is not linked to the indicated TDRA row 2320, the WTRU may follow legacy procedures in step 5 2330. If the DCI does not activate an SP PDSCH in step 3 2315 but instead dynamically schedules one or more PDSCHs, in step 5 the WTRU may determine 2322 whether there are any AP resource sets linked to the indicated TDRA row. If so, in step 8, the WTRU may transmit 2326 the linked AP SRS resource set.If the AP resource set is not linked to the indicated TDRA row, then in step 5, the WTRU may follow legacy procedures (2330).

[0213] For brevity, various examples herein describe linking a PDSCH TDRA table row with one or more SRS resource sets. CSI-RS may be linked in a similar manner, thereby providing integrated and efficient triggering / activation and TDRA of PDSCH, SRS, and CSI-RS for DL ​​bursts. In other words, a CSI-RS resource set (e.g., an NZP CSI-RS resource set, or a ZP CSI-RS resource set, or a CSI interference measurement (IM) resource set) may be configured with a list of PDSCH TDRA table row indexes for which a CSI-RS resource set may be triggered (for AP CSI-RS) or activated (for SP CSI-RS). Alternatively, the configuration of a PDSCH TDRA table row may include a list of CSI-RS resource set IDs.

[0214] Similarly, one or more PUCCH resource allocations may be linked with a PDSCH TDRA table.

[0215] In another exemplary method, a DL burst format table or DL ​​burst format list is configured. A row (entry) of the DL burst format table (list) includes a reference to a row of the PDSCH TDRA table, thereby providing a TDRA for the PDSCH of a burst. The DL burst format table row may also include one or more references to an SRS resource set (e.g., an AP or SP SRS resource set) and / or a CSI-RS resource set, for example, by providing a list of SRS / CSI-RS resource set IDs and PUCCH resources in the row configuration. If the WTRU is configured with DL bursts enabled, the DCI may include a DL burst format indicator field, which may indicate a row of the DL burst format table, which in turn provides the TDRA for the various signals / channels of the DL burst, such as SRS, CSI-RS, PUCCH, etc.

[0216] In some cases, if SP transmission of PDSCH is activated and indicates a TDRA table row to which one or more AP SRS resource sets are linked, the AP SRS resource set may be repeated in subsequent SP DL bursts (until deactivation) using the same relative resource allocation between SRS and PDSCH as in the first DL burst.

[0217] Another example approach to configuring the SRS and / or CSI-RS of a burst is to set a time offset for the PDSCH instead of a time offset for the DCI. For simplicity, the example of SRS is used below, but it can also apply to CSI-RS. The time offset may be in units of timeslots, as in the example discussed below, but may be in other units, such as symbols.

[0218] The SRS resource (or SRS resource set) may occur or start M timeslots before the timeslot of the PDSCH transmission. Alternatively, the SRS resource (or SRS resource set) may occur or start M symbols before the start of the PDSCH transmission. For example, the SRS resource may occur M timeslots (or symbols) before each PDSCH transmission of a DL burst. The value of M may be, for example, 1, 2, or 3. M may be fixed or configurable, for example, for the BWP, DL burst format, PDSCH transmission within the DL burst format, SRS resource, or SRS resource set. The SRS resource (set) may be, for example, an AP or SP.

[0219] In some cases, symbols designated for SRS transmission may be assigned to DL transmission, for example, depending on the configuration or indicated timeslot format. In other cases, symbols designated for SRS transmission may be assigned as flexible or UL symbols, but they may be assigned to another signal / channel that may have higher priority (e.g., synchronization signal), and SSB, PUCCH transmission, PUSCH transmission, etc. If so, the SRS may have to be dropped or adjusted in frequency or in time.

[0220] If dropped, the corresponding conflicting SRS resource or even the entire SRS resource set may be dropped.

[0221] If coordinated in frequency, for example, if a designated SRS transmission collides with another UL transmission of higher priority, the SRS transmission is adjusted so that it is not transmitted in the conflicting RB, for example, by not transmitting the SRS resource in the conflicting RB or by adjusting the starting RB of the SRS resource sufficiently to avoid the collision.

[0222] If adjusted in time, for example, if a designated SRS resource collides with a DL symbol or a higher priority transmission in a flexible symbol or UL symbol (original symbol), the corresponding SRS resource may be moved to one or more earlier or later symbols valid for SRS transmission (e.g., the latest symbol before the original symbol at which the SRS resource may be transmitted or the earliest symbol after the original symbol at which the SRS resource may be transmitted). Multi-symbol SRS resources on consecutive symbols may be shifted (earlier or later) so that the adjusted SRS resource also falls into consecutive symbols. Alternatively, multi-symbol SRS resources on consecutive symbols may be adjusted so that the adjusted SRS no longer falls into consecutive symbols. For example, only the colliding SRS symbol of the SRS resource and the SRS symbol of the SRS resource before the colliding SRS symbol are moved earlier to a valid symbol. Alternatively, only the colliding SRS symbol of the SRS resource and the SRS symbol of the SRS resource after the colliding SRS symbol may be moved later to a valid symbol.

[0223] In one example, the time offset M may be applied to an SRS resource (or SRS resource transmission) when a timeslot offset is not configured for the SRS resource. In another example, the time offset M may be applied to an SRS resource (or SRS resource transmission) even when a (legacy) timeslot offset is configured, e.g., based on the linkage between the SRS resource and a PDSCH TDRA table row, e.g., when the SRS resource transmission is triggered / activated to be part of a DL burst. In such a case, the configured (legacy) timeslot offset may be ignored. In another example, the WTRU may be configured to interpret the (legacy) timeslot offset parameter in the SRS resource configuration as M (or M plus a known integer).

[0224] In some cases, an SRS resource (set) may be transmitted before every Nth PDSCH transmission of a DL burst. For example, if N=2, SRS is transmitted before the first PDSCH and before the third PDSCH of a DL burst, etc. Alternatively, the first SRS resource (set) may be transmitted before the first PDSCH, and then the SRS (first SRS resource (set) or second SRS resource (set)) may be transmitted in a timeslot that is N timeslots (or at least N timeslots) after the initial transmission of the first SRS resource (set) transmission.

[0225] An SRS resource (set) transmission M timeslots before a PDSCH transmission may be combined with the SRS every Nth PDSCH / slot. For example, for M=1 and M=4, the SRS is transmitted every fourth PDSCH slot. Alternatively, the first SRS transmission is in a timeslot before the first PDSCH and a timeslot before a subsequent PDSCH (not necessarily a second PDSCH) such that the timeslot of the subsequent SRS is at least four timeslots after the timeslot of the first SRS transmission, etc. In yet another alternative, the first SRS transmission is in a timeslot before the first PDSCH and a timeslot before a subsequent PDSCH such that the timeslot of the subsequent PDSCH is at least four timeslots after the timeslot of the first SRS transmission. Methods such as these may be useful for rendering CSI to be applied to the PDSCH in the most recent DL burst no older than a certain age, where the state may be determined from the value(s) of M and / or N.

[0226] In some cases, a subset of the configured burst formats may be selected by the MAC CE and mapped to code points in a DCI field (e.g., a burst format indicator field, a TDRA field, etc.). This allows for the configuration of a large set of burst formats, with a typically small subset being indicated by the DCI. The subset may be dynamically adapted (by the MAC CE) to the WTRU traffic, service type, signal quality, channel conditions, network load, etc.

[0227] The WTRU may be configured by the network with one or more SRS resources, one or more CSI-RS resources, and one or more time domain resource allocations (TDRAs) for the PDSCH. The WTRU may be configured by the network with a linkage between the TDRAs and one or more SRS resources. The WTRU may also be configured with a linkage between the TDRAs and one or more CSI-RS resources.

[0228] The WTRU may receive a first DCI including a field with an indication of one of one or more TDRAs for one or more PDSCHs and an indication of a PDSCH frequency domain resource allocation (FDRA). The first DCI may indicate a first set of parameters for the one or more PDSCHs. If the indicated TDRA is linked with one or more SRS resources, the WTRU transmits the one or more SRS resources. The transmission timing of the one or more SRS resources may depend on the transmission timing of one or more PDSCHs. The frequency resource allocation of the one or more SRS resources may depend on the indicated PDSCH FDRA.

[0229] If the indicated TDRA is linked with one or more CSI-RS resources, the WTRU receives the one or more CSI-RS resources. The WTRU receives a second DCI in a second PDCCH or multiplexed with one of the one or more PDSCHs, where the second DCI indicates a second set of parameters for the one or more PDSCHs. The WTRU receives the one or more PDSCHs based on the indicated first set of parameters, including the TDRA and FDRA, and the second set of parameters.

[0230] Although features and elements are described above in particular combinations, those skilled in the art will understand that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) 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 internal hard disks and removable disks, and optical media such as magneto-optical media, CD-ROM disks, and digital versatile disks (DVDs). A processor associated with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. 1. A method for a wireless transmit receive unit (WTRU), comprising: receiving configuration information including a downlink (DL) burst format table defining a plurality of DL burst formats, the DL burst formats including one or more physical downlink shared channel (PDSCH) time domain resource allocations (TDRAs), one or more sounding reference signal (SRS) resources, and / or channel state information reference signal (CSI-RS) resources associated with the DL burst formats; receiving downlink control information (DCI) from the DL burst format table, the DCI having a field indicating a selected DL burst format; transmitting an SRS using the one or more SRS resources associated with the indicated selected DL burst format; receiving CSI-RS using the one or more CSI-RS resources associated with the indicated selected DL burst format, if any; receiving the one or more PDSCHs using the TDRA associated with the indicated selected DL burst format; A method comprising:

2. The configuration information includes SRS resources including an SRS Frequency Domain Resource Allocation (FDRA), and the received DCI indicates frequency resources identified for a scheduled PDSCH, and the method further comprises: determining a set of SRS frequency domain resources for transmitting the SRS based on the configured SRS FDRA and the identified frequency resources of the scheduled PDSCH; The method of claim 1 further comprising:

3. receiving a second DCI having the field indicating one or more transmission or reception parameters for one or more signals in the DL burst; The method of claim 1 further comprising:

4. 4. The method of claim 3, wherein the DCI and the second DCI are received in different bandwidth portions (BWPs).

5. 1. A wireless transmit receive unit (WTRU), comprising: Walkie-talkies, and a processor in communication with the transceiver wherein the processor and transceiver receiving configuration information including a DL burst format table defining a plurality of downlink (DL) burst formats, the DL burst formats including one or more physical downlink shared channel (PDSCH) time domain resource allocations (TDRAs), one or more sounding reference signal (SRS) resources, and / or channel state information reference signal (CSI-RS) resources associated with the DL burst formats; receiving downlink control information (DCI) from the DL burst format table, the DCI having a field indicating a selected DL burst format; Transmitting an SRS using the one or more SRS resources associated with the indicated selected DL burst format; receiving CSI-RS using the one or more CSI-RS resources associated with the indicated selected DL burst format, if any; receiving the one or more PDSCHs using the TDRA associated with the indicated selected DL burst format; The WTRU is adapted to:

6. 6. The WTRU of claim 5, wherein the configuration information includes SRS resources including an SRS Frequency Domain Resource Allocation (FDRA), the received DCI indicates frequency resources for a scheduled PDSCH, and the processor is configured to determine a set of SRS frequency domain resources for transmitting the SRS based on the configured SRS FDRA and the frequency resources identified for the scheduled PDSCH.

7. The processor and transceiver receiving a second DCI having the field indicating one or more transmission or reception parameters for one or more signals in the DL burst; 6. The WTRU of claim 5, further adapted to:

8. 8. The WTRU of claim 7, wherein the DCI and the second DCI are received in different bandwidth portions (BWPs).

9. 1. A method for a wireless base station, comprising: sending configuration information to a wireless transmit / receive unit (WTRU), the configuration information including a downlink (DL) burst format table defining a plurality of DL burst formats, the DL burst formats including one or more physical downlink shared channel (PDSCH) time domain resource allocations (TDRAs), one or more sounding reference signal (SRS) resources, and / or one or more channel state information reference signal (CSI-RS) resources associated with the DL burst formats; sending downlink control information (DCI) to the WTRU, the DCI including a field indicating a selected DL burst format from the DL burst format table; receiving an SRS transmitted by the WTRU using the one or more SRS resources associated with the indicated selected DL burst format; transmitting a CSI-RS to the WTRU using the one or more CSI-RS resources associated with the indicated selected DL burst format, if any; transmitting the one or more PDSCHs using the TDRA associated with the indicated selected DL burst format; A method comprising:

10. 10. The method of claim 9, wherein the configuration information includes SRS resources including an SRS Frequency Domain Resource Allocation (FDRA), the DCI indicates frequency resources identified for a scheduled PDSCH, and the received SRS uses frequency resources based on the SRS FDRA and the identified frequency resources of the scheduled PDSCH.

11. measuring one or more characteristics of the received SRS; sending a second DCI to the WTRU, the second DCI having the field indicating an updated DL burst format from the DL burst format table based on the measured one or more characteristics of the received SRS; 10. The method of claim 9, further comprising:

12. 12. The method of claim 11, wherein the DCI and the second DCI are sent in different bandwidth portions (BWPs).

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