Efficient low latency CSI acquisition in downlink bursts

Abstract

A method and apparatus for a wireless transmit receive unit (WTRU) are disclosed. The WTRU is configured with information including a downlink (DL) burst format table defining a plurality of DL burst formats. The DL burst format includes time domain resource allocation (TDRA), one or more sounding reference signal (SRS) resources, and / or channel state information reference signal (CSI-RS) resources for one or more physical downlink shared channels (PDSCHs) associated with the DL burst format. The WTRU may receive downlink control information (DCI) having a field indicating to the WTRU a selected DL burst format from the DL burst format table, the DL burst format table defining time domain locations of all signals associated with the selected DL burst. The WTRU may then transmit SRS (if any) and receive CSI-RS (if any) and one or more PDSCHs using the TDRA associated with the indicated selected DL burst format. Additional embodiments are disclosed.

Description

[0001] Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 409,672, filed on September 23, 2022, the content of which is incorporated herein by reference. Background Art

[0003] The performance of future wireless communication systems may depend on timely and accurate CSI (Channel State Information). However, in the case of SRS (Sounding Reference Signal)-based DL (Downlink) CSI, the delay between SRS transmission and the corresponding PDSCH (Physical Downlink Shared Channel) may be too long for the proper performance of such future wireless communication systems.

[0004] Dynamically scheduled Physical Downlink Shared Channel (PDSCH) transmission and reception can be based on previous SRS and / or CSI-RS (e.g., for CSI acquisition, beam management, and time-frequency (t / f) synchronization). For time-varying channels (e.g., multi-antenna, high frequency, high mobility, etc.), it is beneficial to transmit / receive SRS and / or CSI-RS as close as possible in t / f to the corresponding PDSCH(s) (given the capabilities of the mobile station and base station, etc.). In legacy systems, PDSCH, SRS, and / or CSI-RS can be separately scheduled / triggered by DL control information (DCI), using: (i) the higher t / f domain flexibility of PDSCH compared to non-periodic SRS and / or CSI-RS, which provides less DCI overhead but sub-optimal t / f allocation of SRS and / or CSI-RS; and / or (ii) similar t / f domain flexibility of PDSCH, SRS, and / or CSI-RS, with higher DCI overhead but better t / f allocation of SRS and / or CSI-RS. A solution to achieve "optimal" SRS and / or CSI-RS t / f allocation (related to PDSCH) with low DCI overhead would be desirable. Summary of the Invention

[0005] 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 time slot / symbol offset is determined based on the PDSCH start time). The frequency domain allocation of the triggered SRS may be based on the PDSCH FDRA in the frequency domain resource allocation (FDRA) DCI field.

[0006] The BS may wish to adjust PDSCH transmission when receiving the SRS triggered by the first DCI. A subsequent second DCI may adjust the information in the first DCI, for example, adjust the PDSCH MCS, rank, t / f resource allocation. The second DCI may be in the second PDCCH (e.g., without blind decoding) or multiplexed in the PDSCH. The CSI-RS (Tracking Reference Signal) for tracking is enhanced to support P3 beam management (UE Rx beam scanning). As described herein, a user equipment (UE) may be interchangeably referred to as a wireless transmit / receive unit (WTRU).

[0007] Embodiments include an electronic device having a wireless transmit / receive unit (WTRU) configurable by a network, the network having one or more SRS resources, one or more CSI-RS resources, and one or more time domain resource allocations (TDRAs) of one or more PDSCHs.

[0008] The performance of future wireless communication systems may depend on timely and accurate CSI (Channel State Information). In the case of SRS (Sounding Reference Signal)-based DL (Downlink) CSI, the delay between SRS transmission and the corresponding PDSCH (Physical Downlink Shared Channel) should be kept as low as possible. Aspects of the present disclosure propose methods for configuring and triggering / activating DL (Downlink) bursts, which may include SRS (Sounding Reference Signal), CSI-RS (Channel State Information Reference Signal), and PDSCH (Physical Downlink Shared Channel) in an order configured for timely DL CSI (Downlink Channel State Information) acquisition and low control overhead.

[0009] Features of the systems described herein include 3GPP target features and releases, advanced MIMO, MIMO evolution, massive distributed MIMO (MD-MIMO), ultra-massive MIMO (UM-MIMO), cell-free MIMO (CF-MIMO), L1, L2 / 3.

[0010] The processes and functions described herein include scheduling, link adaptation, PDSCH (Physical Downlink Shared Channel) resource allocation, PDCCH (Physical Downlink Control Channel), and SRS (Sounding Reference Signal).

[0011] Embodiments described herein include a WTRU configured with multiple DL (downlink) burst formats, the multiple DL burst formats including SRS, CSI-RS, and one or more PDSCHs (Physical Downlink Shared Channels) for DL CSI acquisition, the DL burst formats being indicated in DCI downlink control information, e.g., via the PDSCH TDRA field or via a new field (such as, a DL burst format indicator), where the DL burst format includes the TDRA (time domain resource allocation) of one or more PDSCHs (Physical Downlink Shared Channels), the DL (downlink) burst format may include the temporal location of SRS / CSI-RS configured for the PDSCH TDRA, the DCI being split into a first DCI and a second DCI, the first DCI triggering the DL (downlink) burst format, the second DCI indicating / adjusting PDSCH parameters based on SRS measurements. The second DCI may be received in the PDCCH without blind decoding, or may be multiplexed in the PDSCH. The first DCI and the second DCI 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 enhanced TRS by repetition may facilitate both tracking and beam management through the same RS. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more detailed understanding can be obtained from the following description, which is provided by way of example in conjunction with the accompanying drawings, in which like reference numerals in the figures represent like elements, and in which:

[0013] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0014] Figure 1B is a system diagram of an example wireless transmit / receive unit (WTRU) that may be used in the Figure 1A illustrated communication system according to an embodiment;

[0015] Figure 1C is a system diagram of an example radio access network (RAN) and an example core network (CN) that may be used in the Figure 1A illustrated communication system according to an embodiment;

[0016] Figure 1D is a system diagram of another example RAN and another example CN that may be used in the Figure 1A illustrated communication system according to an embodiment;

[0017] Figure 2 is a schematic diagram of an aperiodic SRS trigger timeline according to an embodiment;

[0018] Figure 3 is a schematic diagram of a DL burst according to an embodiment;

[0019] Figure 4 is a schematic diagram of a DL burst according to another embodiment;

[0020] Figure 5 is a schematic diagram of a DL burst according to yet another embodiment;

[0021] Figure 6 is a schematic diagram of a UL burst according to an embodiment;

[0022] Figure 7 is a flowchart of a WTRU process according to an embodiment;

[0023] Figure 8 is a schematic diagram of a DL burst according to another embodiment;

[0024] Figure 9 is a schematic diagram of a first DCI scheduling DL bursts on multiple carriers according to an embodiment;

[0025] Figure 10 is a schematic diagram of a second DCI triggering SRS transmission according to an embodiment;

[0026] Figure 11 is a schematic diagram of a first PDCCH and a second PDCCH according to an embodiment;

[0027] Figure 12 is a schematic diagram of a second CORESET separated from a first CORESET according to an embodiment;

[0028] Figure 13 is a schematic diagram of multiple rounds of SRS transmission in a DL burst according to an embodiment;

[0029] Figure 14 is a schematic diagram of an SRS sounding bandwidth according to an embodiment;

[0030] Figure 15 is a schematic diagram of partial detection of an SRS sounding bandwidth according to an embodiment;

[0031] Figure 16 is a schematic diagram of a flexible SRS transmission bandwidth according to an embodiment;

[0032] Figure 17 is a schematic diagram of a flexible SRS transmission bandwidth according to another embodiment;

[0033] Figure 18 is a schematic diagram of the adaptation of an SRS start resource bandwidth (RB) and a sounding bandwidth according to an embodiment;

[0034] Figure 19 is a schematic diagram of a (for beam management) TRS with repetition according to an embodiment;

[0035] Figure 20 is a schematic diagram of a (for beam management) TRS with repetition according to another embodiment;

[0036] Figure 21 is a schematic diagram of a link configuration between an SRS resource set and a TDRA table row according to an embodiment;

[0037] Figure 22 is a flowchart of a WTRU process according to another embodiment; and

[0038] Figure 23 is a flowchart of a WTRU process according to yet another embodiment. Detailed Description

[0039] Figure 1A is a schematic diagram illustrating an example communication system 100 in which one or more of the disclosed embodiments may be implemented. The communication system 100 may be a multi-access system that provides content (such as voice, data, video, messages, broadcasts, etc.) to a plurality of wireless users. The communication system 100 may enable a plurality of 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 code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), zero-tail unique word discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0040] As Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112. However, it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a station (STA)) may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop computer, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., remote surgery), an industrial device and application (e.g., a robot and / or other wireless devices operating in the context of an industrial and / or automation processing chain), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0041] The communication system 100 may further include base stations 114a and / or base stations 114b. Each of the base stations 114a, 114b may be any type of device configured to facilitate access to one or more communication networks (such as the CN 106, the Internet 110, and / or other networks 112) by wirelessly coupling with at least one of the WTRUs 102a, 102b, 102c, 102d. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a NodeB, an eNode B (eNB), a home Node B, 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, etc. Although each of the base stations 114a, 114b is depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0042] Base station 114a may be part of 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, etc. 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 cells (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographical area, which may be relatively fixed or may change over time. A cell may also be divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0043] Base stations 114a, 114b may communicate with one or more of WTRUs 102a, 102b, 102c, 102d via air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). Air interface 116 may be established using any suitable radio access technology (RAT).

[0044] More specifically, as described above, 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, etc. For example, base station 114a in RAN 104 and WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), and UMTS UTRA may use Wideband CDMA (WCDMA) to establish air interface 116. WCDMA may include communication protocols such as High Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed Downlink (DL) Packet Access (HSDPA) and / or High Speed Uplink (UL) Packet Access (HSUPA).

[0045] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as, for example, evolved UMTS terrestrial radio access (E-UTRA) which may use long term evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-A Pro to establish an air interface 116.

[0046] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as, for example, NR radio access which may use NR to establish an air interface 116.

[0047] 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 implement LTE radio access and NR radio access together, for example, using the dual connectivity (DC) principle. Accordingly, 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 / from multiple types of base stations (e.g., eNBs and gNBs).

[0048] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as, for example, IEEE 802.11 (i.e., Wi-Fi), IEEE 802.16 (i.e., 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), etc.

[0049] Figure 1AThe base station 114b therein 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 to facilitate wireless connection in a local area (such as a business premise, a home, a vehicle, a campus, an industrial facility, (e.g., an air corridor for drones), a road, etc.). 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 (such as, WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a pico cell or a femto cell. As Figure 1A shown, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106.

[0050] The RAN 104 may communicate with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or IP-based voice transmission (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, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, location-based services, prepaid calls, Internet connection, video distribution, etc., and / or perform advanced security functions such as user authentication. Although Figure 1A not shown in the figure, it will be understood that the RAN 104 and / or the CN 106 may communicate directly or indirectly with other RANs that employ the same RAT or a different RAT as the RAN 104. For example, in addition to being connected to the RAN 104 that may utilize the NR radio technology, the CN 106 may also communicate with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0051] CN 106 can also act as a gateway for the WTRU 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols (e.g., Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) in the TCP / IP Internet protocol family). The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, and the one or more RANs may employ the same RAT or a different RAT as the RAN 104.

[0052] Some or all of the WTRU 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRU 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, Figure 1A the illustrated WTRU 102c may be configured to communicate with a base station 114a and a base station 114b, where the base station 114a may employ a cellular-based radio technology and the base station 114b may employ IEEE 802 radio technology.

[0053] Figure 1B is a system diagram illustrating an example WTRU 102. As Figure 1B shown, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keyboard 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other peripheral devices 138, etc. It will be understood that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with the embodiments.

[0054] The processor 118 can be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, etc. The processor 118 can perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to a transceiver 120, and the transceiver 120 can be coupled to a transmit / receive element 122. Although Figure 1B the processor 118 and the transceiver 120 are depicted as separate components, it will be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0055] The transmit / receive element 122 can be configured to transmit signals to, or receive signals from, a base station (e.g., base station 114a) via an air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 can be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 can be configured to transmit and / or receive both RF and optical signals. It will be understood that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0056] Although the transmit / receive element 122 is depicted as a single element in Figure 1B the WTRU 102 can include any number of transmit / receive elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via the air interface 116.

[0057] The transceiver 120 can be configured to modulate the signals to be transmitted by the transmit / receive element 122 and demodulate the signals received by the transmit / receive element 122. As described above, the WTRU 102 can have multi-mode capabilities. Thus, the transceiver 120 can include, for example, multiple transceivers to enable the WTRU 102 to communicate via multiple RATs (e.g., NR and IEEE 802.11).

[0058] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keyboard 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and may receive user input data from these devices. The processor 118 may also output user data to the speaker / microphone 124, the keyboard 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from any type of suitable memory (e.g., non-removable memory 130 and / or removable memory 132) and store data in the memory. The non-removable memory 130 may include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from a memory that is not physically located on the WTRU 102 (e.g., on a server or a home computer (not shown)) and store data on the memory.

[0059] The processor 118 may receive power from a power supply 134 and may be configured to distribute and / or control the power to other components in the WTRU 102. The power supply 134 may be any suitable device for powering the WTRU 102. For example, the power supply 134 may include one or more dry cells (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), a solar cell, a fuel cell, etc.

[0060] 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) about the current location of the WTRU 102. As a supplement or replacement to the information from the GPS chipset 136, the WTRU 102 may receive location information via an air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be understood that the WTRU 102 may obtain location information by any suitable location determination method while remaining consistent with the embodiments.

[0061] 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 console module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripherals 138 may include one or more sensors. The sensors 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 tactile sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, etc.

[0062] The WTRU 102 may include a full-duplex radio, for which the transmission and reception of some or all signals (e.g., associated with a particular subframe for both UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit to reduce and / or substantially eliminate self-interference via hardware (e.g., a choke) or via signal processing by a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio, for which the transmission and reception of some or all signals (e.g., associated with a particular subframe for UL (e.g., for transmission) or DL (e.g., for reception)).

[0063] Figure 1C is a system diagram of an exemplary RAN 104 and CN 106 according to an embodiment. As described above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRU 102a, 102b, 102c via the air interface 116. The RAN 104 may also communicate with the CN 106.

[0064] The RAN 104 may include eNode-Bs 160a, 160b, 160c, although it will be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with the embodiments. Each of the eNode-Bs 160a, 160b, 160c may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c via the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to the WTRU 102a and / or receive wireless signals from the WTRU 102a.

[0065] Each of the eNode-Bs 160a, 160b, 160c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in the UL and / or DL, etc. As Figure 1C shown, the eNode-Bs 160a, 160b, 160c may communicate with each other via the X2 interface.

[0066] Figure 1C The illustrated CN 106 may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (PGW) 166. Although the above elements are depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0067] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via the S1 interface and may act as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, activation / deactivation of bearers, selection of a specific serving gateway during the initial attachment of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide control plane functions for handover between the RAN 104 and other RANs (not shown) employing other radio technologies (e.g., GSM and / or WCDMA).

[0068] The SGW 164 can be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 can generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 can perform other functions, such as anchoring the user plane during handovers between eNode Bs, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the contexts of the WTRUs 102a, 102b, 102c, etc.

[0069] The SGW 164 can be connected to the PGW 166, and the PGW 166 can provide the WTRUs 102a, 102b, 102c with access to a packet switched network (such as the Internet 110) to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0070] The CN 106 can facilitate communication with other networks. For example, the CN 106 can provide the WTRUs 102a, 102b, 102c with access to a circuit switched network (such as the PSTN 108) to facilitate communication between the WTRUs 102a, 102b, 102c and traditional landline communication devices. For example, the CN 106 can include or communicate with an IP gateway (such as an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 can provide the WTRUs 102a, 102b, 102c with access to other networks 112, which can include other wired and / or wireless networks owned and / or operated by other service providers.

[0071] Although the WTRU is described as a wireless terminal in Figures 1A - 1D , in some representative embodiments, such a terminal can (e.g., temporarily or permanently) use a wired communication interface with the communication network.

[0072] In a representative embodiment, the other network 112 can be a WLAN.

[0073] In a wireless local area network (WLAN) operating in infrastructure basic service set (BSS) mode, there can be an access point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP can have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic destined for an STA from outside the BSS can reach the STA through the AP and can be delivered to the STA. Traffic originating from an STA destined for a destination outside the BSS can be sent to the AP for delivery to the corresponding destination. Traffic between STAs within the BSS can be sent through the AP. For example, the source STA can send traffic to the AP, and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic can be sent between the source STA and the destination STA (e.g., directly between the source STA and the destination STA) using direct link setup (DLS). In some representative embodiments, DLS can use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN operating in independent BSS (IBSS) mode may not have an AP, and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. Communication in IBSS mode can sometimes be referred to as an "ad hoc" communication mode in this document.

[0074] When operating in 802.11ac infrastructure operation mode or a similar operation mode, the AP can send beacons on a fixed channel (e.g., the primary channel). The primary channel can be of a fixed width (e.g., 20 MHz bandwidth) or dynamically set width. The primary channel can be the operating channel of the BSS and can be used by STAs to establish a connection with the AP. In some representative embodiments, carrier sense multiple access with collision avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. For CSMA / CA, STAs including the AP (e.g., each STA) can listen to the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, that particular STA can back off. Only one STA (e.g., only one station) can transmit at any given time in a given BSS.

[0075] High throughput (HT) STAs can communicate using 40 MHz wide channels, for example, by combining the primary 20 MHz channel with an adjacent or non-adjacent 20 MHz channel to form a 40 MHz wide channel.

[0076] A very high throughput (VHT) STA can support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz and / or 80 MHz channels can be formed by combining contiguous 20 MHz channels. The 160 MHz channel can be formed by combining eight contiguous 20 MHz channels, or by combining two non - contiguous 80 MHz channels (which can be referred to as an 80+80 configuration). For the 80+80 configuration, the channel - encoded data can be passed through a segment parser that can divide the data into two streams. The inverse fast Fourier transform (IFFT) processing and time - domain processing can be performed on each stream separately. The streams can be mapped to two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80+80 configuration can be reversed, and the combined data can be sent to the media access control (MAC).

[0077] The sub - 1 GHz operation mode is supported by 802.11af and 802.11ah. The channel operation bandwidth and carrier 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, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non - TVWS spectrum. According to a representative embodiment, 802.11ah can support meter - type control / machine - type communication (MTC), such as MTC devices in a macro - coverage area. The MTC devices can have certain capabilities, such as including limited capabilities that support (e.g., only support) specific and / or limited bandwidths. The MTC devices can include a battery with a battery life above a threshold (e.g., to maintain an extremely long battery life).

[0078] A WLAN system (e.g., 802.11n, 802.11ac, 802.11af, and 802.11ah) that can support multiple channels and channel bandwidths includes a channel that can be designated as the primary channel. The primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or restricted by the STA that supports the minimum bandwidth operation mode among all STAs operating in the BSS. In an example of 802.11ah, for an STA (e.g., an MTC type device) that supports (e.g., only supports) the 1 MHz mode, the primary channel can be 1 MHz wide, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or network allocation vector (NAV) settings can depend on the state of the primary channel. If the primary channel (e.g., due to an STA (which only supports the 1 MHz operation mode) transmitting to the AP) is busy, then all available frequency bands can be considered busy even if most of the available frequency band remains idle.

[0079] In the United States, the available frequency band (which can be used by 802.11ah) is from 902 MHz to 928 MHz. In Korea, the available frequency band is from 917.5 MHz to 923.5 MHz. In Japan, the available frequency band is from 916.5 MHz to 927.5 MHz. Depending on the country code, the total available bandwidth for 802.11ah is 6 MHz to 26 MHz.

[0080] Figure 1D It is a system diagram of an exemplary RAN 104 and CN 106 according to an embodiment. As described above, RAN 104 can communicate with WTRUs 102a, 102b, 102c via air interface 116 using NR radio technology. RAN 104 can also communicate with CN 106.

[0081] RAN 104 may include gNBs 180a, 180b, 180c, but it will be understood that RAN 104 may include any number of gNBs while remaining consistent with the embodiments. gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with WTRUs 102a, 102b, 102c via the air interface 116. In one embodiment, gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 180b may utilize beamforming to transmit signals to and / or receive signals from gNBs 180a, 180b, 180c. Thus, for example, gNB 180a may use multiple antennas to transmit wireless signals to WTRU 102a and / or receive wireless signals from WTRU 102a. In an embodiment, gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers (not shown) to WTRU 102a. A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB180a and gNB 180b (and / or gNB 180c).

[0082] WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or the OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of various or scalable lengths (e.g., including a varying number of OFDM symbols and / or an absolute time of continuously varying length).

[0083] gNBs 180a, 180b, 180c can be configured to communicate with WTRUs 102a, 102b, 102c in stand-alone configuration and / or non-stand-alone configuration. In stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c without accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In stand-alone configuration, WTRUs 102a, 102b, 102c can utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using signals in the unlicensed band. In non-stand-alone configuration, WTRUs 102a, 102b, 102c can communicate / connect with gNBs 180a, 180b, 180c while also communicating / connecting with another RAN (e.g., eNode-Bs 160a, 160b, 160c). For example, WTRUs 102a, 102b, 102c can implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In non-stand-alone configuration, eNode-Bs 160a, 160b, 160c can act as a mobility anchor for WTRUs 102a, 102b, 102c, and gNBs 180a, 180b, 180c can provide additional coverage and / or throughput for serving WTRUs 102a, 102b, 102c.

[0084] Each of gNBs 180a, 180b, 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support for network slicing, DC, interworking between NR and E-UTRA, routing of user plane data to user plane functions (UPFs) 184a, 184b, routing of control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. As Figure 1D shown, gNBs 180a, 180b, 180c can communicate with each other via the Xn interface.

[0085] Figure 1DThe illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and may include data networks (DN) 185a, 185b. Although the foregoing elements are depicted as part of CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0086] The AMF 182a, 182b may be connected via an N2 interface to one or more of the gNBs 180a, 180b, 180c in the RAN 104 and may act 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 the registration area, terminating non-access stratum (NAS) signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b in order to customize the CN support for the WTRUs 102a, 102b, 102c based on the type of service utilized by the WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases (e.g., services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc.). The AMF 182a, 182b may provide control plane functions for handover between the RAN 104 and other RANs (not shown) employing other radio technologies (such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi).

[0087] The SMF 183a, 183b may be connected via an N11 interface to the AMF 182a, 182b in the CN 106. The SMF 183a, 183b may also be connected via an N4 interface to the UPF 184a, 184b in the CN 106. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 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 notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0088] UPF 184a and 184b can be connected to one or more of gNBs 180a, 180b, and 180c in RAN 104 via the N3 interface. The N3 interface can provide access to a packet-switched network (e.g., the Internet 110) for WTRU 102a, 102b, and 102c to facilitate communication between WTRU 102a, 102b, and 102c and IP-enabled devices. UPF 184a and 184b can perform other functions, such as routing and forwarding data packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL data packets, providing a mobility anchor, etc.

[0089] CN 106 can facilitate communication with other networks. For example, CN 106 can include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 106 and the PSTN 108. Additionally, CN 106 can provide access to other networks 112 for WTRU 102a, 102b, and 102c. Other networks 112 can include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRU 102a, 102b, and 102c can be connected to local DNs 185a and 185b via the N3 interface to UPF 184a and 184b and the N6 interface between UPF 184a and 184b and DNs 185a and 185b.

[0090] In view of Figures 1A - 1D and Figures 1A - 1D the corresponding descriptions, one or more or all of the functions described herein with respect to one or more of the following can be performed by one or more emulation devices (not shown): WTRU 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 (one or more) devices described herein. An emulation device can be one or more devices configured to emulate one or more or all of the functions described herein. For example, an emulation device can be used to test other devices and / or simulate network and / or WTRU functions.

[0091] Emulation devices can be designed to perform one or more tests on other devices in a laboratory environment and / or an operator network environment. For example, one or more emulation devices can perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more emulation devices can perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. An emulation device can be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communication.

[0092] One or more emulation devices can perform one or more (including all) functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, an emulation device can be utilized in a test laboratory and / or a test scenario in a non-deployed (e.g., test) wired and / or wireless communication network to perform tests on one or more components. One or more emulation devices can be test devices. An emulation device can send and / or receive data using direct RF coupling and / or wireless communication via an RF circuit (which can include, for example, one or more antennas).

[0093] In MIMO communication, multiple antennas at the transmitter and receiver are used to improve communication performance, e.g., through spatial multiplexing, spatial diversity, and / or beamforming. In a wireless network, multiple transmit / receive antennas can be deployed at a transmit / receive point (TRP). In a traditional wireless network, typically one TRP per cell is used. A TRP is typically equipped with multiple antennas. Recently, TRPs equipped with a large number or even hundreds of antennas have been deployed, supporting large-scale MIMO scenarios.

[0094] Another trend is to deploy additional TRPs within a cell. The benefits of such a deployment are a reduced average distance and path loss between the WTRU and the closest TRP, which allows for lower transmit power and thus less interference in the system. Another benefit is improved spatial diversity, which means that there can be several candidate TRPs that can serve the WTRU. If the radio link to the serving TRP is blocked, the WTRU can be served by another TRP that does not have a blocked radio link.

[0095] In a distributed MIMO system, the antennas are not located at one or a few TRPs. Instead, the antennas are even more distributed throughout the wireless network. In some definitions, distributed MIMO also includes cases with several TRPs. Distributed MIMO transmit / receive can include, for example, coherent joint transmission (in the DL) and reception (in the UL), non-coherent transmission, single-frequency network (SFN)-based transmission, involving distributed antennas or several TRPs.

[0096] A large-scale distributed MIMO system (also known as distributed large-scale MIMO) combines a large number of antennas in a large-scale MIMO system and distributed antennas in a distributed MIMO system. For example, hundreds of antennas that were previously co-located at a large-scale MIMO TRP covering a geographical area are distributed across the area. A subset of the antennas can be co-located at the TRP (sometimes referred to as an access point). Large-scale distributed MIMO deployment promises extremely high theoretical performance under ideal assumptions. However, there are many challenges in achieving these performances in practical applications, including fronthaul, synchronization, etc.

[0097] A sounding reference signal (SRS) can be sent by a WTRU based on network SRS configuration, activation, triggering, etc. The network can receive and measure the SRS, for example, to estimate the uplink (UL) radio channel, estimate the downlink (DL) channel, estimate various parameters such as UE (WTRU) Doppler shift or spread or UE (WTRU) time offset or delay spread, the angular direction of the UE (WTRU), the location of the UE (WTRU), UL beam management, DL beam management, multi-UE (WTRU) pairing for DL or UL multi-user MIMO, etc.

[0098] In some cases (such as in a system that employs time-division duplexing (TDD) and uses DL / UL transceiver calibration or other methods to make the efficient downlink (DL) radio channel including DL transmitter hardware similar or equal to the efficient UL radio channel including UL receiver hardware), an estimate of the downlink (DL) radio channel can be obtained from the estimated UL radio channel. This is generally referred to as DL / UL reciprocity, or simply reciprocity.

[0099] In a system with reciprocity, the SRS can thus be used to obtain DL channel state information at the network side. This is an alternative to the method of estimating DL CSI at the WTRU based on DL RS (such as CSI-RS, SSB, or DMRS) and feeding the quantized or unquantized CSI from the WTRU back to the network. Although DL CSI is used to receive DL transmissions at the WTRU side, DL CSI is used at the network side to appropriately adapt DL transmissions, such as in terms of modulation and coding scheme (MCS), multi-antenna precoding, etc.

[0100] The advantage of SRS-based DL CSI acquisition is that DL CSI is readily available at the network side and can be immediately used to adapt DL transmissions. This means that CSI feedback latency can be avoided, which includes the time between receiving the DL RS and the corresponding CSI feedback transmission as well as the CSI feedback processing latency at the network.

[0101] SRS-based DL CSI acquisition can also be particularly efficient in large-scale distributed MIMO systems. For example, consider a simple example where there are 100 antennas on the network side and 1 WTRU antenna. Thus, the DL CSI includes 100 radio channels. Using DL CSI acquisition based on WTRU measurements of DL RS, 100 DL RSs are required to estimate 100 channels. In addition, the quantized CSI report may need to represent 100 channels. On the other hand, SRS-based DL CSI acquisition only requires a single SRS that can be received at 100 antennas and can be used (taking advantage of reciprocity) to estimate all 100 channels. This example illustrates the potentially significant overhead reduction in DL CSI acquisition in large-scale distributed MIMO systems by using SRS instead of DL RS.

[0102] SRS in 5G NR can provide a flexible framework for WTRU transmission of network-controlled SRS resources. Multiple attributes of SRS resources can be configured. Several of the attributes are discussed below.

[0103] The network can provide a spatial reference RS (target RS) for the SRS resource. The WTRU uses the same spatial domain filters (e.g., UL Tx beam and / or UL Tx panel) as those used for receiving the reference RS (e.g., DL Rx beam and / or DL Rx panel) to transmit the target SRS resource.

[0104] The frequency resources spanned by the SRS resource and the hopping pattern (if any) are also configured. SRS resources can be grouped into SRS resource sets. Some attributes can be configured per SRS resource set. The SRS resources in an SRS resource set can be periodic, semi-persistent (SP), or aperiodic (AP).

[0105] Periodic SRS resources are transmitted periodically after being configured. A spatial reference RS can be configured for the periodic SRS resources.

[0106] Semi-persistent (SP) SRS resources are transmitted periodically after being activated until being deactivated. The activation / deactivation is carried in the MAC CE and applied to the SP SRS resource set, i.e., all the SRS resources in the set are jointly activated / deactivated. A spatial reference RS can be configured for the SP SRS resources. In addition, the activation / deactivation MAC CE can update the spatial relationship RS of the SRS resources in the SRS resource set.

[0107] An aperiodic (AP) SRS resource is transmitted when triggered by downlink control information (DCI) carried in a physical downlink control channel (PDCCH). An AP SRS resource set may be configured with one or more AP SRS resource trigger values. If the DCI indicates an AP SRS resource trigger value for the associated field 'SRS request' equal to the trigger value configured for the AP SRS resource set, the AP SRS resource set is triggered. In other words, the DCI may trigger multiple SRS resource sets.

[0108] An AP SRS resource may be configured with a spatial reference RS. The spatial reference RS of the AP SRS resources in an AP SRS resource set may be updated using a MAC CE.

[0109] A unified transmission configuration indicator (TCI) framework is introduced, in which the spatial reference RS (also referred to as the quasi - co - located (QCL) source RS) of all SRS resources in one or more SRS resource sets may be updated using a MAC CE or DCI. If the spatial reference RS is to be updated using the new mechanism, the spatial reference RS may be configured per SRS resource set. The unified TCI framework allows for the joint and simultaneous update of the TCI states of various DL signals / channels (e.g., PDCCH, PDSCH, CSI - RS) and various UL signals / channels (e.g., PUCCH, PUSCH, SRS). In one example, the TCI state of the PDSCH (including the spatial QCL source RS) and the spatial reference RS of one or more SRS resource sets using "antennaSwitching" are jointly and simultaneously updated to the same DL RS. This allows for low - overhead simultaneous beam switching for both the PDSCH and the SRS used for PDSCH CSI acquisition.

[0110] Reference Figure 2 , an example aperiodic SRS timeline 200 is shown and typically defined, which may be 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 SRS for antenna switching, the minimum time is N2 + Tswitch, as Figure 2 illustrated, where N2 is given in Table 1 below for two different WTRU processing capabilities, and Tswitch is a UL switching gap between 35 - 210 µs (i.e., for a 15 kHz sub - carrier spacing (parameter set µ = 0), approximately ½ - 3 symbols).

[0111] Table 1: N2 for different WTRU processing capabilities

[0112]

[0113] CSI-RS is a multi-purpose DL RS in 5G NR. CSI-RS is organized into CSI-RS resources and CSI-RS resource sets, and a CSI-RS resource set can include one or more CSI-RS resources. Several kinds 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.

[0114] NZP CSI-RS resources carry CSI-RS with WTRU-known parameters and on which the WTRU can perform various signal and channel measurements. Unless otherwise specified, 'CSI-RS resource' and 'CSI-RS resource set' refer to NZP CSI-RS resources and NZP CSI-RS resource sets respectively.

[0115] ZP CSI-RS resources can include resource element (RE) configurations similar to NZP CSI-RS resources, but sometimes do not contain CSI-RS. ZP CSI-RS resources can be used for rate matching of PDSCH.

[0116] CSI IM resources can include a set of REs on which the WTRU can perform noise and interference measurements.

[0117] CSI-RS in NR can be used for various purposes, such as beam management, mobility, CSI acquisition, and time-frequency tracking.

[0118] CSI-RS for beam management can correspond to a CSI-RS resource set configured with the parameter repetition (e.g., with repetition set to 'enabled' or 'off').

[0119] The CSI-RS for tracking (also known as Tracking RS (TRS)) is a CSI-RS resource set with certain properties. The TRS can span one or two adjacent time slots. The WTRU can use the TRS for fine time-frequency tracking. For this purpose, the PDCCH DMRS and the PDSCH DMRS can use the TRS as a QCL source RS, e.g., using QCL type A and QCL type D. QCL type A means that the WTRU can estimate the Doppler frequency shift, Doppler spread, average delay, and delay spread based on the TRS and apply the estimates to the reception of the PDCCH / PDSCH DMRS. QCL type D means that the WTRU can estimate the spatial Rx parameters (e.g., Rx beam and / or Rx panel) based on the TRS for PDCCH / PDSCH DMRS reception. QCL type D can be used in beamforming systems, e.g., at mmWave (millimeter wave), sub-THz, or THz frequencies. The network may use different transmit beams and even transmit different TRSs from different TRPs. Since different transmit beams or TRPs may result in different propagation paths, the fine time-frequency tracking and spatial Rx parameters may be different between different TRSs received by the WTRU.

[0120] CSI-RS resources can generally be periodic, semi-persistent, or aperiodic. The TRS can be periodic or aperiodic. However, the aperiodic TRS generally uses the periodic TRS as a QCL source RS, which means that the periodic TRS is generally configured for the connected-mode WTRU. The aperiodic TRS can be used to allow timely TRS reception before PDCCH / PDSCH reception in a timely manner, rather than transmitting the periodic TRS with a low periodicity.

[0121] The periodic TRS takes the synchronization signal / PBCH block (SSB) as a QCL source of type C (for Doppler frequency shift and average delay). The periodic TRS can also be configured with a QCL source RS of type D (for spatial Rx parameters), and the QCL source RS can be the SSB or a CSI-RS resource for beam management.

[0122] The aperiodic TRS starts at the symbol after the last symbol of the PDCCH that triggers the TRS. In FR1, the minimum delay can be 0 symbols. In FR2, the minimum delay can be given by the WTRU capability (e.g., beamSwitchTiming (beam switching timing) which can be, e.g., 14, 28, or 48 symbols).

[0123] The slot offset between the triggering PDCCH and the corresponding aperiodic TRS is configurable (0, 1, 2,... slots) and can be different between aperiodic CSI-RS resource sets.

[0124] In the context of extending support up to 71 GHz, support for a single DCI that schedules multiple PDSCHs (or multiple PUSCHs) is introduced. The various relevant aspects of the enhancement are summarized here:

[0125] • A single DCI (format 1_1) can schedule up to 8 PDSCHs

[0126] • Different PDSCHs have different transport blocks (TBs)

[0127] • Each PDSCH has 1 TB or each PDSCH has 2 TBs.

[0128] • Each PDSCH is confined within a time slot

[0129] • The indicated PDSCH to HARQ timing is the time slot offset between the time slot of the last PDSCH and the time slot carrying the HARQ-ACK information.

[0130] • HARQ-ACK information is carried in the same PUCCH resource.

[0131] • The DCI includes one (first) MCS for the first TB of the first TB applied to each PDSCH

[0132] • The DCI includes a second MCS for the second TB of the second TB applied to each PDSCH (if applicable).

[0133] • The DCI includes a new data indicator (NDI) for each TB of each PDSCH.

[0134] • The DCI indicates the redundancy version (RV) of the TB of each PDSCH.

[0135] • The DCI includes a HARQ process number that is applied to the first PDSCH.

[0136] • The HARQ process number is incremented by 1 (modulo) for each subsequent PDSCH.

[0137] • The DCI indicates a row in the configured time domain resource allocation (TDRA) table. The TDRA table is extended such that each row indicates up to 8 multi-PDSCHs.

[0138] • Each PDSCH has a separate {start and length indicator value (SLIV), mapping type, scheduling offset K0}.

[0139] • The number of scheduled PDSCHs is implicitly indicated by the number of valid SLIVs in the row of the TDRA table indicated by the DCI.

[0140] • For DCI format 1_1, the WTRU does not “expect” the numberOfRepetitions to be configured for the TDRA table. However, for DCI format 1_2, the numberOfRepetitions can be configured for the TDRA table.

[0141] • The PDSCH can be in consecutive or non - consecutive time slots.

[0142] • If the PDSCH collides with a UL symbol, the PDSCH is discarded.

[0143] • The DCI includes a single TCI field, and this single TCI field can correspond to one or two TCI states (such as in the multi - TRP enhancement of the PDSCH in Rel - 16).

[0144] • One TCI state: The same TCI state is applied to each PDSCH.

[0145] • Two TCI states: The Rel - 16 rules are used for the association between the TCI state and the PDSCH.

[0146] 5G NR sidelink control information (SCI) can be split into stage 1 SCI and stage 2 SCI, where stage 1 SCI is transmitted in the physical sidelink control channel (PSCCH), and stage 2 SCI is multiplexed in the physical sidelink shared channel (PSSCH).

[0147] Stage 1 SCI includes scheduling information for the PSSCH, such as time and frequency resource allocation, DMRS pattern, and MCS. Stage 1 SCI can also include a resource reservation time period, which can also be useful for sidelink WTRUs that are not intended for the PSSCH. Stage 1 SCI can also indicate the format of stage 2 SCI, and the beta offset value of stage 2 SCI that can be used to control the number of modulation symbols (or resource elements) for stage 2 SCI.

[0148] Stage 2 SCI can include various information depending on the format, such as HARQ process number, new data indicator (NDI), redundancy version (RV), source and destination IDs, propagation type indicator, CSI request, etc.

[0149] In Phase 1, the SCI may need to be received by a larger set of WTRUs than the WTRUs targeted by the PSSCH. Thus, the PSCCH (with Phase 1 SCI) may be transmitted in broadcast fashion, e.g., using wide beams, diversity transmission, multi-TRP transmission, and / or SFN transmission, while the PSSCH (including Phase 2 SCI) may be transmitted using narrow beams targeted at the intended WTRU(s).

[0150] The first release of 5G NR is designed for high flexibility and forward compatibility. A potential drawback of the flexible design is the un-necessarily high complexity and latency in the most typical use cases. In subsequent releases of 5G NR, this is addressed by adding configurable operating modes with significantly fewer degrees of freedom but higher efficiency.

[0151] In terms of dynamically obtaining CSI using SRS based on the arrival of DL / UL data bursts, existing cellular communication systems (e.g., 4G LTE, LTE-A, and 5G NR) allow a great deal of flexibility, e.g., in terms of aperiodic SRS triggered by DCI, aperiodic TRS triggered by DCI, and PDSCH / PUSCH dynamically scheduled by DCI. SRS triggering, TRS triggering, and PDSCH / PUSCH scheduling are independent, which allows a great deal of flexibility. However, the flexibility may come at the cost of a higher DCI payload size, greater DCI overhead, and potentially greater latency.

[0152] For future communication systems and deployment scenarios (e.g., large-scale distributed MIMO), timely CSI acquisition is often critical to communication performance. Thus, in order to reduce the latency of CSI acquisition, it may be worthwhile to sacrifice some flexibility. Described below are one or more embodiments of techniques for reducing the latency between the SRS used for CSI acquisition and the corresponding first PDSCH or PUSCH to which the acquired CSI is applied.

[0153] As introduced in the context 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”), typically at the cost of increased signaling overhead and with different processing timelines for different signals / channels. However, in many cases, the same set of signals / channels may be repeated and used in the same order to support DL / UL data transmission.

[0154] For simplicity of presentation, DL-based embodiments are described that can be used for efficient DL data transmission. However, the described embodiments (methods and processes) can also be applied to UL data transmission (e.g., single-panel UL transmission, simultaneous multi-panel UL transmission, UL bursts, etc.), where the PDSCH can be replaced by the PUSCH, and the SRS used for DL CSI acquisition (e.g., using antenna switching) can be replaced by the SRS for UL CSI acquisition (e.g., SRS for codebook-based or non-codebook-based PUSCH operation) and / or the SRS for UL beam management.

[0155] The purpose of DL bursts is to achieve efficient DL data transmission, e.g., by achieving a short delay between SRS transmission and PDSCH reception and low control signaling overhead. One or more typical sets of signals / channels having time relationships designed for a particular WTRU can be repeatedly configured and used.

[0156] A DL burst can be a set of signals / channels that are time-concentrated and used for DL data communication. The signals / channels can include DL and / or UL signals / channels. The signals / channels can be periodic, semi-persistent, and / or aperiodic (and can also be various combinations). Time concentration can refer to the transmission / reception of signals / channels within a certain time duration (e.g., several time slots, subframes, radio frames, milliseconds, etc.). A DL burst can be periodic, semi-persistent, or aperiodic, e.g., based on the attributes of the signals / channels including the DL burst.

[0157] The reception of a DL burst or a part thereof can be scheduled by the network, e.g., using DCI in the PDCCH or via a MAC CE in the PDSCH. The reception of a semi-persistent DL burst or a part thereof can be activated (and deactivated) by the network, e.g., using DCI in the PDCCH or via a MAC CE in the PDSCH. The reception of a periodic DL burst or a part thereof can be configured by the network, e.g., using RRC signaling.

[0158] The various structures, components, and / or timelines of a DL burst or a part thereof can be configurable, indicated by DCI (e.g., trigger, schedule, or activate DCI), or indicated by a MAC control element (CE). A DL burst can include one or more of the following:

[0159] • The first DCI in the first PDCCH, e.g., for scheduling or activating a DL burst or a part of the burst. In some cases, the first DCI can be considered not to be part of the DL burst.

[0160] • One or more SRSs, e.g., for DL CSI acquisition, antenna switching, or beam management.

[0161] • One or more CSI-RSs, e.g., for tracking and / or beam management.

[0162] • A second DCI, e.g., in a second PDCCH or multiplexed in a PDSCH.

[0163] • One or more PDSCH transmissions

[0164] • One or more PUCCH transmissions. In some cases, the PUCCH following a PDSCH may be considered not to be part of a DL burst.

[0165] A burst may have at least partially configurable burst formats. Various exemplary burst formats are illustrated in Figures 3 - 6 .

[0166] Refer to Figure 3 , which shows an exemplary schematic diagram of a DL burst 300 having a second DCI carried in a PDCCH 310 and three PDSCH transmissions 312, 314, 316. Figure 4 An exemplary illustration of a DL burst 400 having a second DCI multiplexed in a first PDSCH 410 is shown. The advantages / disadvantages of multiplexing the second DCI in a PDSCH (as Figure 4 shown) compared to transmitting the second DCI in a PDCCH (as Figure 3 shown) will be further discussed herein. Figure 5 An exemplary illustration of a DL burst 500 having an SRS transmission 515 between a first PDSCH transmission 510 and a second PDSCH transmission 520 and a third DCI piggybacked in the second PDSCH 520 is shown. Figure 6 An exemplary illustration of a UL burst 600 having three PUSCH transmissions 612, 614, and 616 is shown.

[0167] Multiple PDSCHs (or PUSCHs) in a DL burst (or UL burst) may carry different transport blocks or the same transport block, depending on the configuration and / or dynamic indication. In some cases, a subset of PDSCHs (or PUSCHs) may carry the same transport block while other PDSCHs (or PUSCHs) may carry one or more other transport blocks. In an example where there are 4 PDSCHs in a DL burst, the first pair of PDSCHs carry a first transport block and the second pair of PDSCHs carry a second transport block. The transport blocks carried by multiple PDSCHs (or PUSCHs) may be repeated across multiple PDSCHs (or PUSCHs) or mapped to multiple PDSCHs (or PUSCHs), e.g., similar to the conventional PUSCH TB handling on multi-slot PUSCHs in NR.

[0168] Reference Figure 7 illustrates an exemplary high-level WTRU procedure 700. Further details and variations of each step are discussed below. One or more signals / channels in a burst may be cancelled and not transmitted or received. For example, if a DL signal / channel in a burst conflicts with a higher-priority DL signal / channel (e.g., an SSB), or with a symbol that has been configured or indicated as a UL symbol, then that DL signal / channel may be cancelled. For example, if a UL signal / channel conflicts with a higher-priority UL signal / channel, or with a symbol that has been configured or indicated as a DL symbol, then that UL signal / channel may be cancelled.

[0169] In addition, the signals / channels in a burst that are not cancelled may be rate-matched around other signals / channels that may or may not be part of the burst.

[0170] In some systems (e.g., 5G NR), PDCCH monitoring and / or PDCCH monitoring capabilities (e.g., the maximum number of PDCCH blind decodings, the maximum number of non-overlapping control channel elements) are defined within a PDCCH monitoring span (or set), which may correspond to a certain duration (e.g., a certain number of symbols or a certain number of time slots). Turning to the Figure 8 schematic of DL burst 800, the first DCI 805 may be received within the first PDCCH monitoring span 810, while the second 2DCI 815 may be received after the first span 810 (e.g., in a second span or in a later time slot). In one example, the second DCI 815 may be multiplexed in the first PDSCH 820 received after the first span 810. In another example, the second DCI (not shown) may be received in a second PDCCH 830 after the first span 810. The WTRU may also monitor one or more other CORESETs and / or search space sets within the first PDCCH monitoring span 810, e.g., for broadcast PDCCH or group-common PDCCH.

[0171] If the second DCI is received in the second PDCCH, then the second PDCCH may be in the first span 810 or in a subsequent span. Note that although various examples herein may assume OFDM as an exemplary waveform, these examples are equally applicable to single-carrier waveforms, such as single-carrier FDMA.

[0172] A DL burst can be scheduled by a first DCI carried by a first PDCCH. A semi-persistent DL burst can be activated by a first DCI carried by a first PDCCH. Once the semi-persistent DL burst is activated by the first DCI, the semi-persistent DL burst can be deactivated by another DCI carried by another PDCCH.

[0173] In various embodiments, the first DCI can convey one or more of the following information pieces, e.g., by including a corresponding field or by implicit indication via another field or combination of fields. An information piece (in a separate field, e.g.) can include any of the following and will be described in more detail below:

[0174] • DL burst format indicator

[0175] • DL burst indicator

[0176] • SRS request

[0177] • CSI-RS indicator

[0178] • Activation / deactivation of semi-persistent SRS

[0179] • Activation / deactivation of semi-persistent CSI-RS

[0180] • HARQ-related information for one or more PDSCHs

[0181] • Indication of one or more PUCCH resources

[0182] • Resource allocation (RA) for one or more PDSCHs

[0183] • Modulation and coding scheme (MCS)

[0184] • (One or more) antenna ports

[0185] • QCL information

[0186] • Second DCI information

[0187] • BWP and cell / carrier information

[0188] The DL burst format indicator can indicate one of multiple DL burst formats. The burst format can correspond to the structure of the burst (e.g., which components are included, their temporal relationships, etc.). Multiple DL burst formats can be configured, as further described below in connection with the configuration, activation, and triggering of DL bursts.

[0189] The DL burst indicator (or trigger) can indicate that a DL burst is scheduled or activated. If not, the DCI can be used for other purposes, e.g., legacy operations such as scheduling a single PDSCH, requesting AP SRS, etc.

[0190] The DL burst format indicator and / or the DL burst indicator may indicate one or more of the other parameters / fields discussed herein. For example, the DL burst format indicator may convey TDRA, SRS request, CSI-RS indicator, etc.

[0191] The SRS request (or trigger, or indicator) may request the WTRU to transmit SRS resources in a DL burst. The request may also convey various SRS parameters. The SRS may be triggered without an explicit SRS request (e.g., the SRS request may be part of the DL burst format indicator or the PDSCH time domain resource allocation).

[0192] 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. The CSI-RS may be triggered without an explicit CSI-RS trigger (e.g., the CSI-RS indicator may be part of the DL burst format indicator or the PDSCH time domain resource allocation).

[0193] The first DCI may also activate / deactivate SP SRS or SP CSI-RS, which may be part of a DL burst. For example, the first DCI may activate SP SRS or SP CSI-RS and deactivate it after the DL burst, e.g., automatically deactivate after a certain time in or after the DL burst or by explicit deactivation in a DCI after the first DCI.

[0194] In addition, HARQ-related information for one or more PDSCH transmissions can be indicated. This can include an indication of the (one or more) HARQ process numbers for one or more PDSCH transmissions, e.g., by incrementing the HARQ process number for each subsequent PDSCH transmission in a burst. Alternatively, the DCI can include as many HARQ process number fields as there are transport blocks transmitted in the DL burst, which can be less than the number of PDSCH transmissions (e.g., if the transport block is repeated in multiple PDSCH transmissions, or if rules are applied to derive the HARQ process numbers for multiple transport blocks in the DL burst from one HARQ process number in the DCI), or greater than the number of PDSCH transmissions (e.g., if the PDSCH transmission carries multiple transport blocks), or equal to the number of PDSCH transmissions. Alternatively, the HARQ-related information can include a bitmap having a length equal to the number of transport blocks carried in the DL burst, where the first bit value (e.g., "1" or "0") indicates that the TB corresponding to the HARQ process is included in the DL burst. In another case, both the numbering and the bitmap are included. The bitmap can indicate the HARQ processes of the PDSCH transmissions in the burst, while the numbering can indicate the HARQ process number of the first PDSCH transmission. Subsequent PDSCH transmissions can use the next (larger or smaller) HARQ process number set in the bitmap, etc. The numbering can be the HARQ process number or an index into the HARQ process numbers set by the bitmap (e.g., represented by bits).

[0195] The HARQ-related information can include a new data indicator (NDI) and the redundancy version (RV) of the TB of the scheduled PDSCH transmission, e.g., as discussed above in NR Rel-17.

[0196] The first DCI can indicate one or more PUCCH resources that can be used for HARQ-ACK feedback from the PDSCH transmission (e.g., via one or more PUCCH resource indicators and / or one or more PDSCH-to-HARQ feedback timing indicators).

[0197] Time / frequency (t / f) domain resource allocation. One or more PDSCH transmissions can be scheduled by the first DCI. The first DCI can at least partially indicate the time domain resource allocation (TDRA) and / or the frequency domain resource allocation (FDRA). In 5G NR, the TDRA field selects a row (entry) in a configured TDRA table (list). The rows in the table can include the TDRA for one or more PDSCHs. The TDRA for a PDSCH can include the slot offset (k0) between the DCI and the PDSCH, the PDSCH mapping type, the SLIV, and the number of repetitions.

[0198] The TDRA in the DCI of a DL burst can correspond to one or more start and length indicators (SLIVs) for time-domain allocation of the PDSCH (e.g., symbol allocation in a time slot) and / or the time slot offset between the DCI and the time slot including the PDSCH (similar to 5G NR). The TDRA in the first DCI can be the TDRA for the first PDSCH. The TDRA for subsequent PDSCHs can be in the second DCI (or subsequent DCIs).

[0199] If the PDSCH is scheduled / activated by the first DCI, it may be beneficial to be able to adjust the number of PDSCH resource elements (REs) in the second DCI (e.g., adjusted based on the MCS in the second DCI or based on the most recent DL buffer status). Thus, the TDRA in the first DCI can include the start time slot and symbol of the first PDSCH. The length of the first PDSCH (e.g., the number of symbols and / or time slots) can be included in the second DCI. Alternatively, the second DCI can adjust the preliminary length indicated in the first DCI, e.g., via an SLIV or via a length offset that can be added to the preliminary length.

[0200] In addition, the TDRA in the second DCI can include the start time slot and symbol of the second PDSCH, and so on for any subsequent DCIs and PDSCHs. In various examples, the TDRA table is extended to include more signal / channel links in the DL burst or with more signal / channel links in the DL burst, e.g., for more efficient control signaling. In addition to one or more PDSCHs, a TDRA table row can include information about one or more SRSs and / or CSI-RSs or links with one or more SRSs and / or CSI-RSs. The TDRA and TDRA fields can be part of the DL burst format indicator, or vice versa. Configurations of the TDRA table (or DL burst format table) etc. are discussed herein.

[0201] Modulation and coding scheme (MCS). The first DCI can convey one or more MCSs for the (one or more) PDSCHs. One or more MCSs can be applied to one PDSCH, a subset of PDSCHs, or all PDSCHs in the burst. For example, the DCI indicates 1-2 MCSs for 1-2 transport blocks (TBs) applied to each PDSCH in the burst. In another example, the DCI conveys the MCS for each TB in the burst. In some cases, one or more MCSs are partial MCSs or preliminary MCSs, where the second (or subsequent) DCI conveys the remaining partial MCS or adjusted MCS. In some cases, the first DCI also conveys the MCS applicable to the second DCI, which can be the same as or different from the MCS for the corresponding PDSCH.

[0202] One or more antenna ports. The first DCI may convey the PDSCH and PDSCH DMRS antenna ports, including the number of antenna ports. In some cases, the first DCI may indicate one or more PDSCH DMRS line ports, while the second DCI may convey the PDSCH antenna ports, which may be a subset of the PDSCH DMRS antenna ports, for example.

[0203] QCL information. The first DCI may convey QCL information for various signals / channels in a burst (including QCL regarding various time, frequency, and spatial parameters), for example, in the form of one or more TCI fields. The TCI field may correspond to one or more TCI states, which may provide information on the QCL source RS for one or more DL signals / signals and / or one or more UL signals / channels in the burst.

[0204] The QCL information may include one or more spatial source RSs for SRS in the burst. For example, the spatial source RS may be applicable to an SRS resource or an SRS resource set. The QCL information may include one or more QCL source RSs for CSI-RS in the burst. The QCL information may also include QCL information for one or more PDSCHs, such as one or more QCL source RSs. In some cases, one or more CSI-RS resources in the burst may act as the QCL source for one or more PDSCHs. For example, the TRS in the burst may act as the QCL source for each PDSCH in the burst. In another example, the CSI-RS for beam management in the burst may act as the spatial QCL source for one or more PDSCHs in the burst.

[0205] Second DCI information. In addition to what has been 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 the CORESET (e.g., CORESET ID) and / or the search space set (e.g., search space set ID) in which the WTRU may expect the second DCI. In some cases, the first DCI includes information about the second DCI such that only a small amount of blind decoding is still required for the second DCI. For example, a small set of time-frequency locations, PDCCH candidate indices, aggregation level, etc. may be indicated.

[0206] BWP and cell / carrier information. The first DCI may schedule / activate a DL burst on 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 be indicated for a handover 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 on another carrier / cell. Go to Figure 9 , an example of multiple carrier DL bursts 900 is shown. In some cases, the first DCI may schedule DL bursts on multiple BWPs and / or serving cells (or carriers).

[0207] 5G NR supports the use of a single DCI for scheduling one or more PDSCHs. The single DCI conveys the information required to receive one or more PDSCHs. However, in a DL burst, some DCI information may depend on measurements of the SRS in the DL burst (e.g., the MCS of the PDSCH). Therefore, the control information may be split between the first DCI and subsequent DCIs in the DL burst. The second DCI is used as an example, but similar information may be conveyed by subsequent DCIs (e.g., the third DCI, the fourth DCI, etc.). However, in some cases, a single DCI (the first DCI) schedules / activates the DL burst, and no subsequent DCI is part of that burst.

[0208] In some embodiments, the second DCI may include one or more of the following information:

[0209] • MCS information

[0210] • (One or more) antenna ports

[0211] • FDRA

[0212] • QCL information

[0213] • SRS information

[0214] • Pre-emption and cancellation indication

[0215] • Subsequent DCI information

[0216] It may be appropriate to convey MCS information in the second DCI because it can take into account SRS measurements. The MCS may apply to one or more PDSCHs. The complete MCS information may be carried in the second DCI. Alternatively, partial or adjusted MCS may be carried in the second DCI.

[0217] For example, the first DCI can convey the range of MCS, while the second DCI can convey the MCS within that range. For example, the first DCI can convey the modulation scheme (e.g., QPSK, 16-QAM, etc.), while the second DCI can convey the coding rate used with the modulation scheme. For another example, the first DCI can convey the MCS table, while the second DCI can convey the exact MCS used within the MCS table. This division may be beneficial for the timeline of the WTRU receiver because assuming that the PDSCH demodulation operation can be performed knowing only the modulation format (obtained after decoding the first DCI), the PDSCH demodulation can be completed before the second DCI is decoded. After decoding the second DCI and obtaining the coding rate, the PDSCH can be decoded (e.g., based on the demodulated soft bits).

[0218] 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 can adjust the MCS level in the first DCI by -4, -3, -2, -1, 0, +1, +2, or +3. The MCS offset can adjust the MCS level not lower than the minimum MCS level and not higher than the maximum MCS level.

[0219] In another example, the second DCI conveys rate matching parameters applied to one or more PDSCHs (e.g., the PDSCH where the DCI is multiplexed, the next PDSCH, or one or more subsequent PDSCHs). The rate matching parameters can indicate one or more rate matching patterns from a set of rate matching pattern configurations. The DCI can also convey to which one or more PDSCH transmissions the rate matching parameters are applied.

[0220] In another example, the second DCI conveys puncturing parameters applied to one or more PDSCHs (e.g., the PDSCH where the DCI is multiplexed, the next PDSCH, or one or more subsequent PDSCHs). The puncturing parameters can indicate one or more puncturing patterns from a set of puncturing pattern configurations. The DCI can also convey to which one or more PDSCH transmissions the puncturing parameters are applied.

[0221] In some cases, the second DCI can convey the PDSCH DMRS and / or PDSCH antenna ports. In the case where the second DCI is carried in the PDCCH, the second DCI can indicate the PDSCH DMRS and PDSCH antenna ports (e.g., as indicated in 5G NR).

[0222] In another example, for instance, if the second DCI is multiplexed with the PDSCH, or if the second DCI is received in a different PDCCH, the first DCI may indicate the PDSCH DMRS antenna port. The second DCI may indicate whether the PDSCH antenna port set is the same as the PDSCH DMRS antenna port, or whether it is a subset of the PDSCH DMRS antenna port. For example, the second DCI may provide the network with an opportunity to reduce the PDSCH transmission rank at a later stage, e.g., due to the latest SRS measurement (which may indicate a channel change (e.g., an interruption of the dominant path)) or due to multi-user scheduling.

[0223] A field of 1 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. For a 1-bit field, rank reduction may mean a rank reduction by 1 or a 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 the antenna ports of the PDSCH DMRS that will be used for the PDSCH. If multiple PDSCH DMRS antenna ports have been specified by the first DCI, the second DCI itself may be received on a particular antenna port (e.g., the PDSCH DMRS antenna port with the lowest index, or the PDSCH DMRS antenna port that is also used for phase-tracking RS). Alternatively, the DCI may be replicated / duplicated on multiple PDSCH DMRS antenna ports.

[0224] 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 RBs of the first DCI FDRA, e.g., the starting RB or the ending RB. 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. If the second DCI is multiplexed in the PDSCH and is located (or close to) an edge RB, the second DCI FDRA may adjust the other edge. This may be useful when the FDRA of the PDSCH in which the second DCI is multiplexed is adjusted. If the second DCI FDRA provides a new FDRA, the second DCI FDRA may be restricted to include the RBs carrying the second DCI.

[0225] Before receiving the second DCI (and the corresponding PDSCH), the WTRU may know in advance (e.g., through configuration, indication, or rules in the specification) the maximum RB set that the second DCI may indicate, such as the maximum bandwidth or the maximum RB offset magnitude. This can help the WTRU avoid receiving DL signals / channels with an unnecessarily large reception bandwidth.

[0226] The second DCI may indicate QCL information, e.g., one or more QCL source RSs (and the corresponding QCL types) for the DMRS of one or more PDSCHs, or 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 RS may be a signal in the DL burst, e.g., an SRS resource or a CSI-RS (e.g., a TRS or CSI-RS for beam management).

[0227] Go to Figure 10 , the second DCI 1012 may trigger or cancel a subsequent SRS transmission 1020 in the burst 1000. The second DCI 1012 may activate or deactivate semi-persistent (SP) SRS. In addition, the second DCI 1012 may indicate or update the spatial QCL reference RS (e.g., a previous CSI-RS in the burst) for a subsequent SRS transmission, e.g., by including the corresponding TCI field in the second DCI 1012).

[0228] The second DCI (or a subsequent DCI) may include a preemption indication for past or upcoming transmissions (e.g., PDSCH, PDCCH, PUSCH, PUCCH, CSI-RS, or TRS), where some resources are indicated as being preempted. For past transmissions, the WTRU may assume that the expected signal / channel was not transmitted on the preempted resources, e.g., resulting in PDSCH puncturing. For upcoming transmissions, the WTRU may "assume" that the expected signal / channel will not be transmitted on the preempted resources, e.g., resulting in PDSCH puncturing. In addition, an upcoming DL or UL transmission may be cancelled, e.g., an upcoming PDSCH transmission or an upcoming SRS transmission may be cancelled. One difference between preemption and cancellation may be that preemption refers to a set of resources (e.g., RBs and / or symbols), i.e., the resources are not used for the original transmission, while cancellation may refer to the cancellation of the transmission of a channel or signal.

[0229] The second DCI may include information about the (one or more) subsequent DCIs in the burst. As described above, the information may be the same or similar to the information about the second DCI in the first DCI. In some cases, the second DCI is transmitted in the second PDCCH.

[0230] For timely CSI applications, it may be beneficial to reduce the latency between the transmission of the second DCI and the subsequent PDSCH. In state-of-the-art systems, a major part of the DCI decoding latency may be due to significant blind decoding efforts for multiple different PDCCH candidates with different aggregation levels, DCI formats, etc. To reduce the DCI decoding latency (and simultaneously reduce WTRU operations, power consumption, etc.), it may be beneficial to reduce the amount of blind decoding required for the second DCI. In some cases, when the time-frequency location, aggregation level, DCI format, etc. are known to the WTRU after decoding the first DCI, blind decoding is not performed. A drawback may be reduced PDCCH transmission flexibility. However, this drawback may be minor as the flexibility of the first PDCCH can be maintained.

[0231] In various examples, the second PDCCH is received in the same CORESET as the first PDCCH. This may have various implications such that the QCL source, CORESET frequency resources, CORESET duration, CORESET pool index, etc. are the same for the second PDCCH and the first PDCCH. The first PDCCH may be received in the first search space set associated with the CORESET. The second PDCCH may be received in the second search space set associated with the same CORESET or linked to the first search space set. In some cases, some time-domain attributes of the second search space set (e.g., periodicity, slot offset, or symbols within a slot) may be configured as part of the DL burst configuration. The second search space set may be aperiodic and triggered upon detection of the first DCI. The second search space set may be semi-persistent and activated upon detection of the first DCI.

[0232] In some cases, various parameters of the first PDCCH carrying the detected first DCI as well as the first DCI are also used for the second PDCCH and the second DCI, such as one or more of the following:

[0233] • A set of resource elements (e.g., control channel element (CCE) index or resource element group (REG)) (e.g., with respect to the first CORESET symbol or the first symbol in a slot).

[0234] • PDCCH candidate index

[0235] • Aggregation level

[0236] • DCI payload size

[0237] • DCI format

[0238] • DCI CRC size

[0239] • Precoder granularity

[0240] • (One or more) TCI states

[0241] • (One or more) PDCCH DMRS scrambling parameters

[0242] • CORESET pool index

[0243] 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. After decoding the first DCI, the WTRU may know the time slot and starting symbol of the second PDCCH. For example, the time slot and starting symbol of the second PDCCH may be configured as part of the 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 PDCCH and the second PDCCH 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 associated CORESET and / or search space set), and the scheduling information may include time and / or frequency offset values.

[0244] Note that if the PDCCH candidate indices of the first PDCCH and the second PDCCH are the same, the resource element set (or CCE index or REG) may be different, for example, if the two PDCCHs are in different time slots or different monitoring time spans. Figure 11 An exemplary illustration is shown, where the first DCI is received in the first PDCCH 1110 on the m-th PDCCH candidate at aggregation level L in the CORESET, and the second DCI is also received in the second PDCCH 1120 on the m-th PDCCH candidate at aggregation level L in the same CORESET, and the m-th PDCCH candidate at aggregation level L corresponds to different RE sets. The first PDCCH / DCI 1110 may be blindly decoded in the corresponding CORESET and search space set, similar to legacy systems. However, the second PDCCH / DCI 1120 may be directly decoded without the need for blind decoding because its parameters (such as candidate index, aggregation level, etc.) can be given once the first DCI is correctly decoded. Note, Figure 11 Any signals / channels other than the first PDCCH and the second PDCCH in the DL burst are not shown.

[0245] In some cases, the first PDCCH is received in the first CORESET and the first search space set, and the second PDCCH may be received in the second CORESET.

[0246] The second CORESET may be located 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 than the first CORESET (and thus also in a different BWP).

[0247] In some cases, the second PDCCH is received in the second search space set. In some cases, the search space set for the second PDCCH is not configured or defined. The first and second search space sets may be linked by configuration. After decoding the first DCI, the WTRU may determine the parameters of the second PDCCH / DCI based on the search space set (the second search space set) linked to the search space set on which the first DCI was received and the corresponding CORESET (the second CORESET).

[0248] In some cases, the second CORESET (e.g., its ID) and / or the second search space set (e.g., its ID) are configured in a DL burst format, e.g., the DL burst format may be included in the configuration of a certain BWP or cell.

[0249] In the case where the first CORESET and the second CORESET are different (e.g., are configured differently, or when one or more of the parameters of the second CORESET can be derived from the parameters of the first CORESET while other parameters may be fixed), the PDCCH candidate index and aggregation level of the second PDCCH may still be the same as those of the first PDCCH. This can be achieved by making the two CORESETs have the same configuration in at least some aspects such that the same PDCCH candidate index and aggregation level also exist in the second CORESET. This is similar to the solution adopted for multi-TRP PDCCH repetition in 5G NR Rel-17, in which the DCI is repeated among the PDCCH candidates across two linked search space sets and CORESETs. Here, the second DCI is not a repetition of the first DCI. Additionally, the position of the second PDCCH in time (e.g., time slot and / or symbol) may not be fixed in time, but may depend on the information in the first DCI. PDCCH repetition may occur within a time slot in the same BWP.

[0250] An improvement for the case with the first CORESET and the second CORESET is to allow a different number of PDCCH candidates for a certain aggregation level, in particular fewer candidates in the second CORESET than in the first CORESET. For example, if the first DCI is decoded in the PDCCH candidate m1 at the aggregation level L in the first CORESET, then the second PDCCH can be received in the PDCCH candidate m2 at the aggregation level L, where m2 = mod(m1, M2), where M2 is the number of PDCCH candidates at the aggregation level L in the second CORESET.

[0251] The frequency domain resource allocation (FDRA) of the second CORESET can be explicitly configured in the CORESET configuration, as in legacy 5G NR. In one example, the FDRA of the second CORESET is at least partially indicated in the first DCI. For example, the CORESET FDRA can be based on the PDSCH FDRA, such that an overlap between the CORESET and the PDSCH FDRA can be achieved, which may be beneficial for various reasons (such as improved channel estimation, reduced receiver bandwidth, etc.). For example, if the CORESET bandwidth is less than or equal to the PDSCH bandwidth, then the CORESET FDRA can be adjusted such that it overlaps with the PDSCH bandwidth, for example, by setting the lowest CORESET PDSCH resource block to be aligned with the lowest PDSCH resource block, or by setting the highest CORESET resource block to be aligned with the highest PDSCH resource block, or by setting the center frequency of the CORESET to be aligned with the center frequency of the PDSCH. If the CORESET bandwidth is greater than the PDSCH bandwidth, then the configured CORESET FDRA can be used. Alternatively, the configured CORESET starting RB is adjusted using the minimum number that achieves full overlap in frequency with the scheduled PDSCH.

[0252] Figure 12Example 1200 is shown in which the second CORESET 1220 is separated from the first CORESET 1210. The WTRU decodes the PDCCH candidate m2 in the second CORESET 1220 (for aggregation level L) because it decodes the first DCI in the PDCCH candidate m1 in the first CORESET 1210 (for aggregation level L) based on a rule / relationship between m1 and m2 (e.g., m2 = m1, or m2 = mod(m1, M2)). The exemplary illustration also shows the second CORESET 1220 that is frequency-overlapped with the scheduled PDSCH 1230, and the overlap can be achieved by the method described above. The exemplary illustration also shows cross-BWP scheduling of DL bursts. Note that, for clarity, Figure 12 not all signals / channels of the DL burst may be shown.

[0253] 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 can also be applied to the case where the second DCI is multiplexed in the PDSCH. The second DCI can be separately encoded, modulated, and multiplexed in the PDSCH in a manner similar to how the second-stage sidelink control information (SCI) is multiplexed in the physical sidelink shared channel (PSSCH). However, the function of the second DCI can be different from the function of the second-stage SCI. In various embodiments, the second DCI is intended to provide the most up-to-date control information (e.g., the most recent MCS and antenna ports based on the just-measured SRS) for (one or more) subsequent PDSCHs, as well as other adjustments (e.g., cancellation) to (one or more) PDSCHs. The purposes of the first-stage and second-stage SCI include providing the information most relevant to many WTRUs in the first-stage SCI (e.g., resource reservation), while the second-stage SCI provides the information relevant to the (one or more) WTRUs expected to receive the PSSCH.

[0254] The encoding, modulation, multiplexing, etc. of the second DCI into the PDSCH can also follow the principles of multiplexing uplink control information (UCI) in the PUSCH in 5G NR. This may be useful, for example, in avoiding the simultaneous transmission of PUCCH and PUSCH.

[0255] In the case of a multi-layer PDSCH, a single-layer DCI can be transmitted on one of the layers, e.g., on the lowest-numbered antenna port, or on the PDSCH DMRS antenna port that is also used for phase-tracking RS. Alternatively, the DCI symbol can be replicated and transmitted on each antenna port. The latter method is used in 5G NR for the multiplexing of control information in shared channels.

[0256] In some embodiments, to allow DCI decoding to complete before PDSCH decoding, it may be advantageous to multiplex DCI early in the PDSCH (e.g., in the first symbol or first few symbols). To better channel estimate, it may also be beneficial to multiplex DCI in the REs close to the DMRS. The advantage of multiplexing the second DCI in the PDSCH instead of in a separate PDCCH may be simpler and more efficient resource allocation, since no separate PDCCH resources are used. In addition, multiplexing in the PDSCH can compress the timeline, since the information in the DCI can be encoded and modulated later in the transmission processing pipeline.

[0257] Sounding reference signal (SRS) in a DL burst. The DL burst can include WTRU transmissions of one or more SRS resources for CSI acquisition purposes. Depending on various factors (such as WTRU mobility, carrier frequency, deployment scenario, etc.), the CSI obtained from SRS measurements can be valid for a certain duration (e.g., the channel coherence time). If the duration of CSI validity is longer than the DL burst duration, one round of SRS transmissions in the DL burst (e.g., at the start of the DL burst or even before the DL burst) may be sufficient. However, if the duration of CSI validity is shorter than the DL burst duration, multiple rounds of SRS transmissions throughout the DL burst may be required. In addition, the CSI obtained from SRS measurements can be valid within a certain 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).

[0258] Reference Figure 13 , an illustration of multiple rounds of SRS transmissions is shown in DL burst 1300. One round of SRS transmissions can correspond to the transmission of one or more SRS resources for CSI acquisition that are typically time - concentrated (e.g., several symbols or one time slot). The SRS resources can correspond to one or more sets of SRS resources, such as sets of SRS resources using antenna switching. Figure 13 A DL burst 1300 with two rounds of SRS transmissions 1310, 1320 is shown, such that the network can obtain valid CSI for both the first PDSCH 1315 and the second PDSCH 1325. The CSI obtained at the network can be reflected in the information carried in the second DCI and the third DCI, e.g., in the (one or more) indicated MCSs for PDSCH 1 1315 and PDSCH 2 1325.

[0259] The position and / or presence of SRS resources in a DL burst can be configured (see below) or indicated (e.g., via MAC CE or DCI, or a combination). In cases where SRS is triggered by DCI, one or more rounds of SRS can be triggered by the first DCI. In some cases, the first round of SRS can be triggered by the first DCI, while subsequent round(s) of SRS (if any) can be triggered by subsequent DCIs, as Figure 13 shown.

[0260] In some cases, if ACK / NACK bundling is configured, the presence of subsequent rounds of SRS can affect the bundling of PDSCH ACK / NACK. For example, the ACK / NACK corresponding to PDSCH transmissions between subsequent two rounds of SRS can be bundled. If there is only the first round of SRS in a DL burst, then all ACK / NACKs in the burst can be bundled. In some cases, ACK / NACK is bundled based on the set of PDSCHs affected by the second DCI, the third DCI, etc. For example, the ACK / NACK from the PDSCH with the second DCI having multiplexing and the ACK / NACK from subsequent PDSCHs are bundled, and the ACK / NACK from the PDSCH with the third DCI having multiplexing and the ACK / NACK from subsequent PDSCHs are bundled, and so on. Such a scheme may be beneficial because the link quality (e.g., error rate, SINR, or SNR) can vary between subsequent rounds of SRS or subsequent DCIs.

[0261] In some cases, one or more SP SRS resources can be activated by DCI (e.g., the first DCI) in a DL burst, or by an activated MAC CE, or by an RRC message. In some cases, SP SRS resources can 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 a DL burst but less useful after the DL burst. Therefore, SP SRS resources can be automatically deactivated during or after the DL burst. For example, after the last PDSCH transmission in the burst, the SP SRS resource is deactivated, i.e., the first SP SRS resource transmission opportunity after the last PDSCH transmission in the burst is not sent. Alternatively, the number (or number of time slots) of SP SRS resource transmissions before deactivation can be configured, e.g., as part of the DL burst format indicator or as part of the SP SRS resource configuration.

[0262] Flexible SRS transmission timing. For example, in 5G NR (as described above in connection with SRS in 5G NR) having an SRS request DCI (which has 2 bits), DCI-based triggering of AP SRS is supported. Since one value ("00") corresponds to no SRS request, in the example, thus only up to three different sets of AP SRS resources can be triggered by DCI. In the example, the slot offset between the DCI and the slot of the triggered SRS resource is configured and not flexible. In the example, the symbols in the slot for transmitting the SRS resource are also configured and not flexible. Therefore, mainly due to the limited flexibility of AP SRS, it may be difficult in 5G NR to combine dynamic PDSCH scheduling with variable slot and symbol offsets with the simultaneous triggering of a suitable SRS resource that keeps the latency between SRS and PDSCH low.

[0263] To address this issue, the SRS offset relative to the triggering DCI (e.g., the 1st DCI, or the 2nd or subsequent DCIs) can follow the offset of the DL burst. If the latency between the DCI and the first PDSCH is short (e.g., two slots), then the first round of SRS can also be transmitted with a short latency (e.g., about one slot after the DCI). On the other hand, if the latency between the 1st DCI and the first PDSCH is longer (e.g., 6 slots), then the first round of SRS can also be transmitted after a longer latency (e.g., after about 5 slots).

[0264] A similar issue also exists for SP SRS in 5G NR which also has a configured slot offset. The solution can be to make the SP SRS slot offset dependent on the SP PDSCH slot offset, e.g., have the SP SRS transmission be N slots or symbols before the SP PDSCH, where N can be fixed (e.g., equal to 1 slot or 21 symbols) or configurable.

[0265] Flexible SRS transmission bandwidth. The purpose of SRS transmission within the DL burst is to adjust or improve the DL transmission scheme of one or more PDSCHs that have been scheduled on certain frequency resources, such as MCS or multi-antenna selection, precoding, or beamforming. However, in 5G NR, the frequency domain attributes of the SRS resources in 5G NR are typically configured and not flexible. This means that sometimes it is not possible to dynamically trigger SRS transmission only on the frequency resources that will be used for (one or more) subsequent PDSCH transmissions, except in special cases. Therefore, broadband SRS can be configured.

[0266] In one embodiment, SRS transmission in a DL burst can be enhanced such that the frequency resources for SRS can be adjusted or determined based on the FDRA of a subsequent PDSCH (e.g., the subsequent PDSCH immediately following, or the first PDSCH after a certain moment, where the moment can occur at a time delay after the start or end of the SRS transmission, and where the time delay can be fixed or network-configurable).

[0267] The SRS resources can span one or more symbols. The SRS resources can be configured to probe a certain probing bandwidth. There are several ways in which SRS resources can probe a certain probing bandwidth (e.g., transmit on a certain probing bandwidth). Several examples are as follows: Each RB of the probing bandwidth can be probed in a single-symbol SRS resource, e.g., as Figure 14 shown in (a); each RB of the probing bandwidth can be repeatedly probed in multiple symbols of a multi-symbol SRS resource (with repetition), e.g., as Figure 14 shown in (b); each RB of the probing bandwidth can be probed on multiple symbols of a multi-symbol SRS resource (with frequency hopping), where different symbols probe different sets of RBs, e.g., as Figure 14 shown in (c); a subset of the RBs of the probing bandwidth can be probed in a single-symbol SRS resource (partial probing), e.g., as Figure 15 shown in (a); a subset of the RBs of the probing bandwidth can be repeatedly probed in multiple symbols of a multi-symbol SRS resource (partial probing with repetition), e.g., as Figure 15 shown in (b); and a subset of the RBs of the probing bandwidth can be probed on multiple symbols of a multi-symbol SRS resource, where different symbols probe different sets of RBs (partial probing with frequency hopping), e.g., as Figure 15 shown in (c).

[0268] In some embodiments, the transmission of SRS RBs can be omitted. First, consider the scenario where the scheduled PDSCH FDRA is equal to or within the configured SRS probing bandwidth. In legacy 5G NR operation, the SRS resources would be transmitted according to their configured probing bandwidth. This could result in an unnecessarily large SRS transmission bandwidth, especially if the configured SRS bandwidth is significantly larger than the PDSCH bandwidth. SRS transmission in the RBs not used for the PDSCH may not be helpful for fast adaptation within the DL burst. In one example, the WTRU can omit SRS transmission outside of the PDSCH bandwidth, as Figure 16 shown, where (a)-(c) can correspond to Figure 14The cases shown in (a)-(c). The dashed boxes may represent SRS symbols / RBs that are configured but not transmitted, while the solid boxes represent transmitted SRS symbols / RBs, which are within the configured symbols / RBs.

[0269] In another example, SRS transmission may also be omitted in the 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 in one or more RBs within the PDSCH bandwidth (i.e., not at the edge) may be omitted. The number of omitted RBs may be based on the coherence bandwidth. For example, the RB omission pattern at each edge (e.g., the number and / or location of the omitted RBs) may be configured by the network for configuration in the WTRU. In some cases, multiple patterns may be configured by the network, and one of the patterns may be dynamically indicated, e.g., by a DL MAC CE indication or indicated in a DCI (e.g., the first DCI, or the second or subsequent DCI). SRS RB omission may also be configured and / or indicated as part of the DL burst format configuration and indication.

[0270] The omitted 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 fewer gains for frequency-selective and channel-dependent scheduling. However, preliminary CSI acquisition before the first DCI is not excluded. Additionally, in future systems, the gains from frequency-selective scheduling may be smaller, e.g., due to a large number of antennas, wideband resource allocation, or line-of-sight scenarios. Systems with a large number of antennas (e.g., massive MIMO, holographic MIMO, or large-scale distributed MIMO) may experience channel hardening, which results in smaller variations than known channel fading given appropriate multi-antenna processing. However, the wideband allocation of the PDSCH can reduce the possibility of scheduling the PDSCH only at the channel peaks and avoiding deep fades (in frequency).

[0271] Reference Figure 17 , for partial sounding, the transmitted SRS bandwidth may also be reduced, as shown in Figure 17 (a)-(c), Figure 17 (a)-(c) may correspond to Figure 15Examples in (a)-(c). For partial probing, the network may use interpolation to estimate the channels on the unprobed RBs. However, if the SRS RB omission based on PDSCH FDRA is directly applied to the SRS resources with partial probing, the transmitted SRS resources may not provide the transmitted RBs for interpolation on the edge RBs of the PDSCH. Therefore, in the case of partial-probed SRS, if no SRS is configured for the edge RBs of the PDSCH, the WTRU may send a certain number of SRS RBs (e.g., one RB, or the whole block) in the next block of the SRS RB configured to be closest in frequency to the edge RB, as Figure 17 shown by the grey squares (e.g., one or more RBs) in. This scheme may result in an SRS transmission bandwidth that is larger than the PDSCH bandwidth, but still smaller than the configured SRS probing bandwidth.

[0272] The DCI triggering the SRS resource transmission (e.g., the first DCI, the second DCI, or subsequent DCIs) may indicate whether the transmission should follow the configured bandwidth, or whether the WTRU should adapt the SRS bandwidth in accordance with the scheduled PDSCH FDRA, e.g., via a 1-bit field or a multi-bit field, or implicitly via another field (e.g., the PDSCH TDRA field or the DL burst indicator field). The WTRU may configure whether it is more optimal for the WTRU to apply the frequency adaptation described herein for each SRS resource or SRS resource set, or whether it is more optimal for the WTRU to apply the configured probing bandwidth as in legacy systems.

[0273] In another method, the WTRU may adjust the starting RB and / or the probing bandwidth of the SRS resources 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 subsequent DCIs), the WTRU may set the SRS starting RB to the lowest RB of the PDSCH FDRA. However, the effective starting RB of the SRS may have a different granularity from the lowest RB of the PDSCH FDRA. For example, the SRS starting RB may be adjusted in steps of 4 RBs, while the PDSCH FDRA may use a granularity of 1 RB. If so, the WTRU may, for example, set the SRS starting RB to the highest effective starting RB such that the lowest starting RB of the PDSCH FDRA is within the SRS probing bandwidth. Alternatively, the SRS starting RB may be set to the lowest effective starting RB within the PDSCH bandwidth.

[0274] The WTRU may also set the probing bandwidth of the triggered SRS resources to be equal to the bandwidth of the PDSCH. The probing bandwidth granularity may be different from the PDSCH bandwidth granularity. Refer to Figure 18, To handle this situation, for example, the sounding bandwidth can be set to be greater than or equal to the minimum effective sounding bandwidth of the illustrated PDSCH bandwidth. Alternatively, the sounding bandwidth can be set to be less than or equal to the maximum effective sounding bandwidth of the PDSCH bandwidth. In another alternative, the sounding bandwidth can be set to the minimum effective sounding bandwidth that results in the highest overlap between the SRS bandwidth and the PDSCH bandwidth.

[0275] The WTRU can be configured with a certain maximum SRS transmission bandwidth per SRS symbol. To increase the sounding bandwidth beyond the maximum bandwidth, the WTRU can add frequency hopping in other symbols. The WTRU can be configured with the maximum number of SRS symbols in the SRS resource, and the WTRU can use said symbols for additional frequency hopping. If the sounding bandwidth cannot be extended to cover the PDSCH bandwidth even with additional hopping (e.g., due to a limited number of symbols, or a limited WTRU SRS transmission bandwidth, which can be due to a limited UL transmission bandwidth or a limited UL transmission power), the WTRU can separate the hopping in frequency so that the sounding bandwidth covers the PDSCH bandwidth through partial sounding.

[0276] In some cases, the WTRU may not be able to match the PDSCH FDRA to the SRS sounding bandwidth and may instead use the configured SRS sounding bandwidth. This means that the PDSCH bandwidth can be greater than the SRS sounding bandwidth. In such a case, it may be beneficial for the WTRU to send the SRS sounding bandwidth near the center of the PDSCH bandwidth. In other words, the WTRU can select the lowest effective SRS starting 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.

[0277] In the case of using an antenna-switched SRS resource set where there are more Rx antennas than Tx antennas, the WTRU can send multiple SRS resources from different antenna sets in different symbols. The above methods can be applied to each of these SRS resources since it may be beneficial to sound the bandwidth that will be used for the PDSCH for all Rx antennas.

[0278] The DL burst can include various types of CSI-RS resources and CSI-RS resource sets. For example, the DL burst can include one or more TRSs to assist the receiver and demodulation performance of the (one or more) PDCCHs and / or (one or more) PDSCHs in the burst.

[0279] In some cases, a DL burst may include CSI-RS for beam management (e.g., a CSI-RS resource set configured with repeated "on", or a CSI-RS resource set configured with the parameter "repetition"). Such a CSI-RS resource set can be used by a WTRU to adjust its DL Rx beam, which may be useful when the network has adjusted its (one or more) DL Tx beam / (one or more) precoder based on SRS measurements.

[0280] The TRS and CSI-RS for beam management can be very similar. Both signal structures are based on repetition, a TRS that allows the WTRU to estimate Doppler-related parameters, and a CSI-RS for beam management that allows the WTRU to attempt different DL Rx beams. Since the WTRU may need to keep its Rx beam fixed during the TRS symbol to properly estimate the tracking parameters, the TRS (e.g., an aperiodic (AP) TRS) may not be suitable for DL Rx beam scanning. Additionally, for the TRS, L1 measurement reporting (e.g., L1 reference signal received power (RSRP)) may not be supported. If the TRS is immediately followed by a single-port CSI-RS for beam management, the WTRU may not be able to assume the same antenna port is being used, even if the TRS and CSI-RS are QCL.

[0281] Reference Figure 19 Referring to resource schematic diagram 1900, for more efficient resource utilization, the TRS and CSI-RS for beam management can be combined into one structure (e.g., referred to as a TRS with beam management), which can be based on the TRS structure 1910 in 1-2 time slots, but with a certain degree of repetition added after the legacy TRS 1910, such as two additional repetitions 1912. The same RS values as in the legacy TRS 1910 can be repeated on subsequent symbols. For example, in the PDSCH bandwidth of a subsequent PDSCH, or in the bandwidth spanned by all PDSCH transmissions in a DL burst, or in a configurable bandwidth, the TRS repetition 1912 can be added over the entire (legacy) TRS bandwidth, or only over a portion of the TRS bandwidth. A portion of the TRS 1910 bandwidth can be centered or aligned along the edge with the subsequent PDSCH in the DL burst. The repetition 1920 can share the antenna port with the legacy CSI-RS resources in the TRS.

[0282] In some embodiments, the presence of the TRS repetition can be indicated to the WTRU in the DCI (e.g., in the first DCI, the second DCI, or a subsequent DCI). If the repetition is not indicated, the WTRU may expect the legacy TRS without repetition.

[0283] In one example, a TRS with repetition can be configured by including additional CSI-RS resources in the legacy TRS (e.g., a set of CSI-RS resources configured with the optional parameter trs-info, or a set of CSI-RS resources with trs-info and an additional parameter trsRepetition). Except for possibly different symbol indices, the additional CSI-RS resources in the set can have the same configuration as the legacy TRS resources, e.g., single-port and in the same subcarriers. In some cases, a set of CSI-RS resources containing a TRS with repetition can be configured with an optional parameter repetition set set to "enabled".

[0284] In another example, the additional CSI-RS resources may not be explicitly configured. Instead, a new optional parameter (e.g., repetitionNumber) can be configured into the set of CSI-RS resources configured with trs-Info. This parameter can take values such as 1, 2, or 3 to indicate the number of repetitions in subsequent symbols after the explicitly configured CSI-RS resources, or 2, 3, or 4 to indicate the total number of repetitions. Figure 19 The examples in can be achieved, for example, by repetitionNumber = 2 in the previous example and repetitionNumber = 3 in the following example.

[0285] Reference Figure 20 , in another variant, only one resource or a subset of the legacy TRS CSI-RS resources 2010 can be followed by (one or more) repetitions 2012. Similar to the previous examples, the repetitions 2012 can be achieved by configuring additional CSI-RS resources into the set of CSI-RS resources. Instead, also similar to the previous examples, the set can be configured with an optional repetitionNumber parameter. In this case, for example, if the repetition occurs after the 2nd CSI-RS resource in a time slot or in symbols not used by other previous TRSs in the time slot, a higher repetition number can be configured. Additionally, which of the 2 or 4 CSI-RS resources in the legacy TRS the repetition occurs after is configurable, e.g., by an optional parameter repetitionResource, which can be, for example, 0, 1, 2, or 3, indicating the 1st, 2nd, 3rd, or 4th resource in the TRS). Instead, the repetition resource can be fixed to, for example, the last one. Figure 20 The styles in can be achieved, for example, by setting repetitionNumber = 4 (if calculating additional transmissions) or repetitionNumber = 5 (if calculating the total number of subsequent transmissions). For Figure 20In an exemplary example, the example parameter repetitionResource can be configured to 3 because the repetition occurs after the last symbol. Note that the DL burst (format) may not include CSI-RS.

[0286] Different WTRUs may have different capabilities, e.g., in terms of processing timelines. Before 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:

[0287] • The minimum time between the PDCCH and the SRS triggered by the PDCCH

[0288] • The minimum time between the PDCCH and the AP CSI-RS triggered by the PDCCH

[0289] • The minimum time between the CSI-RS and the PDSCH, e.g., when the CSI-RS is the QCL source RS of the PDSCH DMRS.

[0290] • The CSI-RS can be a TRS, a CSI-RS for beam management, a TRS with beam management, etc.

[0291] • The minimum time can be different for different QCL types and can be different in different frequency ranges. For example, the minimum time in FR1 can be 0.

[0292] • The minimum time between the PDCCH (e.g., the second PDCCH or subsequent PDCCHs) without blind decoding and the corresponding PDSCH.

[0293] • The minimum time between the DCI multiplexed in the PDSCH and the RS triggered by the DCI. The time can be different for different RSs (e.g., SRS or CSI-RS).

[0294] • The PDSCH processing timeline if the DCI is multiplexed in the PDSCH (e.g., when the DCI includes various information related to PDSCH reception and / or decoding such as MCS).

[0295] DL bursts can be configured, activated, and / or triggered. The network can configure the WTRU with a DL burst configuration, which can include one or more DL burst formats. The DL burst configuration can also include various other configuration parameters, several of which have been mentioned above. The DL burst format can be based on the WTRU capabilities, e.g., it can not disrupt the minimum timeline reported by the WTRU. The network can also consider the WTRU traffic (including QoS requirements) and mobility when configuring the DL burst, as well as considerations regarding scheduling and system efficiency, etc. Thus, for example, due to different WTRU processing capabilities, traffic, and mobility, the network can configure different WTRUs with different DL burst formats.

[0296] The DL burst configuration can be configured per DL BWP or per serving cell.

[0297] Configuration of a TDRA table for scheduling multiple PDSCHs using a single DCI can be supported. This feature can be a building block in the DL burst format configuration.

[0298] Separate configuration of aperiodic and semi-persistent SRS resources and SRS resource sets can also be supported, and the SRS resources and SRS resource sets can be identified by their IDs. The aperiodic SRS resources have configurable slot offsets and symbol allocations.

[0299] Similarly, various types of CSI-RS resources and CSI-RS resource sets can also be configured and identified by their IDs.

[0300] One way to configure the DL burst format is to associate zero, one, or more SRS resources or SRS resource sets to the rows in the configured PDSCH TDRA table (e.g., as described above). Since a row in the PDSCH TDRA table corresponds to one or more PDSCHs, and each PDSCH has a separate slot offset relative to the scheduling DCI (e.g., the 1st DCI, or the 2nd DCI, or subsequent DCIs) and its symbol allocation within a slot, the network can also configure the SRS resource set for that row at an appropriate timing for the number of PDSCHs and their time offsets.

[0301] This can be achieved, for example, by configuring a list of PDSCH TDRA table row indices in an SRS resource or SRS resource set (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 subsequent DCIs), each SRS resource set having that particular TDRA table row index (e.g., i) configured in its list is triggered / activated by the DCI. SRS resources without a configured list or with an empty list will not be triggered / activated by any TDRA index in the DCI (however, it can be triggered by legacy methods, e.g., a particular SRS request value, if available).

[0302] An alternative way to link a PDSCH TDRA table row to 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.

[0303] Figure 21 An exemplary illustration of the link 2100 between the non-periodic SRS resource sets 2110, 2112, 2114, 2116 and the rows in the 8-row TDRA table 2125 is shown. Rows 2 - 7 can correspond to DL bursts, since the TDRA table row indices between 2 and 7 will schedule / activate the PDSCH according to the TDRA and the corresponding SRS resource sets 2112, 2114, and 2116 based on the link between the AP SRS resource set and the TDRA row index. In this example, rows 0 and 1 are not linked to SRS resources, so an indication of row 0 or row 1 can only correspond to the PDSCH TDRA. However, the AP SRS can use the legacy SRS request field (if present) of TDRA row 0 or row 1 to trigger. This example also shows that the AP SRS resource set 0 2110 does not have configured TDRA row parameters. This means it is not linked to certain TDRA table row indices (and thus not triggered by certain TDRA table row indices).

[0304] In an alternative or complementary method, MAC CE can be used to associate one or more SRS resources or SRS resource sets with TDRA row indices. Associating a new SRS set to a TDRA row index can clear one or more SRSs previously associated with that index. Note that the methods described above can eliminate the need for an SRS request field in the DCI and can not increase the number of bits indicating the TDRA table row, while at the same time the method can significantly increase the potential for improving / adapting (one or more) TDRA for SRS transmissions according to the dynamic scheduling of one or more PDSCHs.

[0305] Go to Figure 22, an exemplary method 2200 for a WTRU is shown. In a first step, the WTRU may be configured 2205 with an SRS resource set (e.g., an AP or SP SRS) and a PDSCH TDRA table. One or more SRS resource sets may be configured to be linked to one or more TDRA table rows, according to the Figure 21 previous example in. In a second step, the WTRU may decode 2210 the first DCI scheduling the PDSCH (e.g., DCI format 1_0, 1_1, 1_2, or a new DCI format), and include a TDRA field indicating the TDRA table row. In a third step, the WTRU may determine 2215 whether any SRS resource sets are linked to the indicated TDRA table row. If so, in a fourth step, the linked SRS resource sets may be triggered / activated 2220 and thus transmitted by the WTRU. In addition to the transmission of one or more linked SRSs, the WTRU may follow the legacy process. The WTRU may receive the scheduled (one or more) PDSCHs. If no SRS resource sets are linked to the indicated TDRA table row 2215, then in a fifth step, the WTRU may follow 2225 the legacy process and receive the scheduled (one or more) PDSCHs accordingly.

[0306] Reference Figure 23, in exemplary method 2300, an SP SRS resource set can be linked 2305 to a TDRA table row. If the first DCI activates one or more SP PDSCHs by indicating a row in the TDRA table, the linked SP SRS resource set can also be activated. A TDRA table row can be linked to both (one or more) AP SRS resource sets and (one or more) SP SRS resource sets. To handle this situation, in step 1, the WTRU can be configured 2305 with links between one or more AP SRS resource sets and one or more rows in the PDSCH table and links between one or more SP SRS resource sets and one or more rows in the PDSCH table. In step 2, the WTRU can decode 2310 the first DCI that schedules the PDSCH (e.g., DCI format 1_0, 1_1, 1_2, or a new DCI format), and includes a TDRA field that represents the TDRA table row. In step 3, the WTRU can determine 2315 whether the DCI activates the SP PDSCH. If so, in step 4, the WTRU can determine 2320 whether any SP resource sets are linked to the indicated TDRA row. If so, in step 6, the WTRU can transmit 2325 the linked (one or more) SP SRS resource sets, e.g., after activating the (one or more) SP SRS resource sets or after interpreting the indicated TDRA row as an SP SRS resource set activation command. If no SP resource sets are linked 2320 to the indicated TDRA row, in step 5, the WTRU can follow 2330 the legacy process. If the DCI does not activate 2315 the SP PDSCH in step 3, but instead dynamically schedules one or more PDSCHs, then in step 5, the WTRU can determine 2322 whether any AP resource sets are linked to the indicated TDRA row. If so, in step 8, the WTRU can transmit 2326 the linked (one or more) AP SRS resource sets. If no AP resource sets are linked to the indicated TDRA row, then in step 5, the WTRU can follow 2330 the legacy process.

[0307] For simplicity, the various examples in this document describe the linking of PDSCH TDRA table rows to one or more SRS resource sets. CSI-RS can be linked in a similar manner to provide unified and efficient triggering / activation and TDRA for PDSCH, SRS, and CSI-RS in a DL burst. 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) can be configured with a list of PDSCH TDRA table row indices, and the CSI-RS resource set can be triggered (for AP CSI-RS) or activated (for SP CSI-RS). Alternatively, the configuration of a PDSCH TDRA table row can include a list of CSI-RS resource set IDs.

[0308] Similarly, one or more PUCCH resource allocations can be linked to the PDSCH TDRA table.

[0309] In another exemplary method, a DL burst format table or a DL burst format list is configured. The rows (entries) of the DL burst format table (list) can include references to rows in the PDSCH TDRA table to provide TDRA for the PDSCH in the burst. The DL burst format table rows can also include one or more references to SRS resource sets (e.g., AP or SP SRS resource sets) and / or CSI-RS resource sets, e.g., by providing a list of SRS / CSI-RS resource set IDs in the configuration of the row, and (one or more) PUCCH resources. If the WTRU is configured with an enabled DL burst, the DCI can include a DL burst format indicator field that can indicate a row in the DL burst format table, which in turn provides TDRA for various signals / channels (e.g., SRS, CSI-RS, PUCCH) in the DL burst.

[0310] In some cases, if the SP transmission of the PDSCH is activated and a TDRA table row linked to one or more AP SRS resource sets is specified, the (one or more) AP SRS resource sets can be repeated (until deactivated) in subsequent SP DL bursts, using the same relative resource allocation between the SRS and the PDSCH as in the first DL burst.

[0311] In another exemplary method of configuring SRS and / or CSI-RS in a burst, a time offset with respect to the PDSCH is configured instead of a time offset with respect to the DCI. For simplicity, an example using SRS is used below, but it can also be applied to CSI-RS. The time offset can be in units of time slots as in the examples discussed below, but it can also be in another unit such as symbols.

[0312] The SRS resource (or SRS resource set) can appear or start in M time slots before the time slot in which the PDSCH transmission occurs. Alternatively, the SRS resource (or SRS resource set) can appear or start in M symbols before the start of the PDSCH transmission. For example, an SRS resource can appear in M time slots (or symbols) before each PDSCH transmission of a DL burst. The value of M can be, for example, 1, 2, or 3, etc. For example, for a BWP, DL burst format, PDSCH transmission in a DL burst format, SRS resource, or SRS resource set, M can be fixed or configurable. The SRS resource (set) can be, for example, an AP or an SP.

[0313] In some cases, the symbols designated for SRS transmission can be allocated for DL transmission, for example, according to a configured or indicated time slot format. In other cases, the symbols designated for SRS transmission can be allocated as flexible symbols or UL symbols, but they may have been allocated to another signal / channel that may have a higher priority, such as a synchronization signal, SSB, PUCCH transmission, PUSCH transmission, etc. If so, the SRS may have to be discarded, or adjusted in frequency or time.

[0314] If discarded, the corresponding conflicting SRS resource or even the entire SRS resource set can be discarded.

[0315] If adjusted in frequency (e.g., if the designated SRS transmission conflicts with another UL transmission of higher priority), the SRS transmission is adjusted so that it does not transmit on the conflicting RBs, for example, by not transmitting the SRS resource on the conflicting RBs, or by adequately adjusting the starting RB of the SRS resource to avoid the conflict.

[0316] If adjusted in time (e.g., if the specified SRS resource collides with a higher priority transmission in one or more DL symbols or one or more flexible or UL symbols (one or more original symbols)), the corresponding SRS resource can be moved to one or more earlier or later symbols that are valid for SRS transmission (e.g., the latest one or more symbols before the one or more original symbols in which the SRS resource can be transmitted, or the earliest one or more symbols after the one or more original symbols in which the SRS resource can be transmitted). A multi-symbol SRS resource on consecutive symbols can be moved (earlier or later) such that the adjusted SRS resource also falls on consecutive symbols. Alternatively, a multi-symbol SRS resource on consecutive symbols can be adjusted such that the adjusted SRS no longer falls on consecutive symbols. For example, only the colliding SRS symbols in the SRS resource and the SRS symbols in the SRS resource that are before the colliding SRS symbols can be moved to be earlier than one or more valid symbols. Alternatively, only the colliding SRS symbols in the SRS resource and the SRS symbols in the SRS resource that are after the colliding SRS symbols can be moved to be after one or more valid symbols.

[0317] In one example, if no slot offset is configured for the SRS resource, a time offset M can be applied to the SRS resource (or SRS resource transmission). In another example, a time offset M can be applied to the SRS resource (or SRS resource transmission) even if an (legacy) slot offset has been configured (e.g., if the SRS resource transmission has been triggered / activated as part of a DL burst, e.g., based on a link between the SRS resource and a PDSCH TDRA table row). In this case, the configured (legacy) slot offset can be ignored. In another example, the WTRU can be configured to interpret the (legacy) slot offset parameter in the SRS resource configuration as M (or M plus a known integer).

[0318] In some cases, the SRS resource (set) can be transmitted before every Nth PDSCH transmission in a DL burst. For example, if N = 2, the SRS is transmitted before the 1st PDSCH and the 3rd PDSCH in the DL burst, and so on. Alternatively, the first SRS resource (set) can be transmitted before the 1st PDSCH, and then the SRS (the first SRS resource (set) or the second SRS resource (set)) can be transmitted in a slot that is N slots (or at least N slots) after the first transmission of the first SRS resource (set).

[0319] The SRS resource (set) transmission in M time slots before (one or more) PDSCH transmissions can be combined with the SRS before every Nth PDSCH / slot. For example, in the cases of M = 1 and M = 4, the SRS is transmitted in the time slot before every 4th PDSCH. Alternatively, the first SRS transmission is in the time slot before the 1st PDSCH and in the time slots before subsequent PDSCHs (not necessarily the 2nd PDSCH), such that the time slots of subsequent SRSs are at least 4 time slots after the time slot of the first SRS transmission, and so on. In yet another alternative, the first SRS transmission is in the time slot before the 1st PDSCH and in the time slots before subsequent PDSCHs, such that the time slots of subsequent PDSCHs are at least 4 time slots after the time slot of the first SRS transmission. Methods such as this may be useful for keeping the CSI applied to the PDSCH in a DL burst no later than a certain age and as up-to-date as possible, and the state of the CSI can be determined according to the values of M and / or N.

[0320] In some cases, a subset of the configured burst formats can be selected by the MAC CE and mapped to the code points of a DCI field (e.g., the burst format indicator field, the TDRA field, etc.). This will allow the configuration of a large set of burst formats, while the usual small subset can be indicated by the DCI. The subset can be changed (by the MAC CE) in accordance with the WTRU traffic, service type, signal quality, channel conditions, network load, etc.

[0321] The WTRU can 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) of the PDSCH. The WTRU can be configured by the network with a link between the TDRA and one or more SRS resources. The WTRU can also be configured with a link between the TDRA and one or more CSI-RS resources.

[0322] The WTRU can receive a first DCI that includes a field having an indication of one of the one or more TDRAs for one or more PDSCHs and an indication of the PDSCH frequency domain resource allocation (FDRA). The first DCI can indicate a first parameter set for one or more PDSCHs. If the indicated TDRA is linked to one or more SRS resources, the WTRU transmits the one or more SRS resources. The transmission timing of the one or more SRS resources can depend on the transmission timing of the one or more PDSCHs. The frequency resource allocation of the one or more SRS resources can depend on the indicated PDSCH FDRA.

[0323] If the indicated TDRA is linked to one or more CSI-RS resources, the WTRU receives the one or more CSI-RS resources. The WTRU receives the second DCI in a second PDCCH or multiplexed with one of the one or more PDSCHs, and the second DCI indicates a second parameter set for the one or more PDSCHs. The WTRU receives the one or more PDSCHs based on the indicated first parameter set (including TDRA and FDRA) and the second parameter set.

[0324] Although the features and elements have been described above in particular combinations, one of ordinary skill in the art will understand that each feature or element can be used separately or in any combination with other features and elements. Additionally, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via 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 storage devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor associated with the software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host.

Claims

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

2. The method according to claim 1, wherein the configuration information includes an SRS resource, the SRS resource includes SRS frequency domain resource allocation (FDRA), and wherein the received DCI indicates a frequency resource for identification of the scheduled PDSCH, the method further comprising: Determining an SRS frequency domain resource set for transmitting the SRS based on the configured SRS FDRA and the identified frequency resource of the scheduled PDSCH.

3. The method according to claim 1, further comprising: Receiving a second DCI having a field indicating one or more transmit or receive parameters of one or more signals in a DL burst.

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

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

6. The WTRU according to claim 5, wherein the configuration information includes SRS resources, the SRS resources comprising SRS frequency domain resource allocation (FDRA), wherein the received DCI indicates the frequency resources for the scheduled PDSCH, and wherein the processor is configured to determine an SRS frequency domain resource set for transmitting the SRS based on the configured SRS FDRA and the identified frequency resources of the scheduled PDSCH.

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

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

9. A method for a radio base station, the method comprising: sending configuration information to a wireless transmit receive unit (WTRU), the configuration information including a DL burst format table defining a plurality of downlink (DL) burst formats, wherein the DL burst format includes time domain resource allocation (TDRA) of one or more physical downlink shared channels (PDSCHs) associated with the DL burst format, one or more sounding reference signal (SRS) resources, and / or one or more channel state information reference signal (CSI-RS) resources; 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; if any, sending CSI-RS to the WTRU using the one or more CSI-RS resources associated with the indicated selected DL burst format; and transmitting the one or more PDSCHs using the TDRA associated with the indicated selected DL burst format.

10. The method according to claim 9, wherein the configuration information includes SRS resources, the SRS resources comprising SRS frequency domain resource allocation (FDRA), wherein the DCI indicates the identified frequency resources for the scheduled PDSCH, and wherein the received SRS uses frequency resources based on the SRS FDRA and the identified frequency resources of the scheduled PDSCH.

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

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

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