Methods and apparatuses for dmrs-free space cca transmission and reception

Abstract

A method performed by a wireless transmit / receive unit (WTRU) may comprise: receiving a PDSCH associated with a space CCA transmission, wherein the space CCA transmission includes a group of REs, including: a first group of REs; a second group of REs; a third group of REs; and a fourth group of REs; constructing a first space CCA view and a second space CCA view in a receive antenna domain in a space CCA region; and decoding the first group of REs, the second group of REs, and the fourth group of REs in the space CCA transmission.

Description

METHODS AND APPARATUSES FOR DMRS-FREE SPACE CCA TRANSMISSION AND RECEPTIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 525,209, filed July 6, 2023, the contents of which are incorporated herein by reference.BACKGROUND

[0002] Machine learning may refer to a type of algorithms that solve a problem based on learning through experience (“data”), without explicitly being programmed (“configuring set of rules”). Machine learning can be considered as a subset of Al. Different machine learning paradigms may be envisioned based on the nature of data or feedback available to the learning algorithm For example, a supervised learning approach may involve learning a function that maps an input to an output based on a labeled training example, wherein each training example may be a pair consisting of the input and the corresponding output. For example, an unsupervised learning approach may involve detecting patterns in the data with no pre-existing labels. For example, a reinforcement learning approach may involve performing a sequence of actions in an environment to maximize the cumulative reward. In some embodiments, it is possible to apply machine learning algorithms using a combination or interpolation of the above-mentioned approaches. For example, a semi-supervised learning approach may use a combination of a small amount of labeled data with a large amount of unlabeled data during training. In this regard semi-supervised learning may be considered as falling between unsupervised learning (with no labeled training data) and supervised learning (with only labeled training data).SUMMARY

[0003] A method performed by a wireless transmit / receive unit (WTRU) may comprise: receiving a physical downlink shared channel (PDSCH) associated with a space canonical correlation analysis (CCA) transmission, wherein the space CCA transmission includes a group of resource elements (REs), including: a first group of REs for carrying data associated with a first layer; a second group of REs for carrying data from the first layer and a second layer, wherein a transmit power difference between the first layer and the second layer is greater than a threshold; a third group of REs for carrying a CCA phase correction reference symbol; and a fourth group of REs for carrying data from the first layer and data from the second layer, wherein the transmit power of the first layer is equal to the transmit power of the second layer; constructing a first space CCA view and a second space CCA view in a receive antenna domain in a space CCA region; and decoding the first group of REs, the second group of REs, and the fourth group of REs in the space CCA transmission. The method may further comprise receiving configuration information associated with a space CCA transmission. The method may further comprise utilizing the third group of REs for a phase correction.

[0004] The configuration information may include a layer specific space CCA region configuration. The configuration information may include the configuration information includes a percentage of overlap between the first layer and the second layer. The space CCA regions may include the first group of REs, the second group of REs, and the third group of REs. The first space CCA view may be constructed from a first set of receive antenna elements and the second space CCA view is constructed from a second set of receive antenna elements. The first set of receive antenna elements may not not overlap with second set of receive antenna elements.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, wherein like reference numerals in the figures indicate like elements, and wherein:

[0006] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented;

[0007] FIG. 1 B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment;

[0008] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A according to an embodiment;

[0009] FIG. 1D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1A according to an embodiment;

[0010] FIG. 2A-D are diagrams illustrating NR DMRS symbol configuration Type 1 for 4x4 MIMI;

[0011] FIG. 3 is a diagram illustrating DMRS based channel estimation and equalization;

[0012] FIGs. 4A-4C are diagrams illustrating various PDSCH transmission;

[0013] FIG. 5 is a diagram illustrating a PDSCH with space CCA transmission;

[0014] FIG. 6 is a diagram illustrating a PDSCH with space CCA transmission;

[0015] FIG. 7 is a flowchart illustrating a procedure performed by a WTRU;

[0016] FIG. 8 is a graph illustrating Layer 1 BER performance;

[0017] Fig. 9 is a diagram illustrating a PDSCH with space CCA transmission; and

[0018] FIG. 10 is a graph illustrating a throughput vs SNR.DETAILED DESCRIPTION

[0019] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple accesssystem that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), singlecarrier FDMA (SC-FDMA), zero-tail unique-word discrete Fourier transform Spread OFDM (ZT-UW-DFT-S- OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0020] As shown in FIG. 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (ON) 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though itwill be appreciated 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 telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0021] The communications systems 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or the other networks 112. 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 eNode B, a next generation NodeB, such as a gNode B (gNB), a new radio (NR) NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0022] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, and the like. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (notshown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0023] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0024] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed Uplink (UL) Packet Access (HSUPA).

[0025] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0026] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using NR.

[0027] 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 instance using dual connectivity (DC) principles. Thus, the air interface utilized by 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 , an eNB and a gNB).

[0028] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e , Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, InterimStandard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0029] The base station 114b in FIG 1A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106.

[0030] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1 A, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may be utilizing a NR radio technology, the CN 106 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0031] The CN 106 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or the other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0032] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102cshown in FIG. 1 A may be configured to communicate with the base station 114a, which may employ a cellularbased radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0033] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0034] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0035] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0036] Although the transmit / receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0037] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0038] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit) The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0039] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li- ion), etc.), solar cells, fuel cells, and the like.

[0040] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment

[0041] The processor 118 may further 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 e-compass, a satellite transceiver, a digital camera (for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and / or Augmented Reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors. The sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor and the like.

[0042] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e g., associated with particular subframes for both the 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 either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e g., for transmission) or the DL (e g., for reception)).

[0043] FIG. 1C is a system diagram illustrating the RAN 104 and the ON 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0044] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0045] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0046] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. While the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0047] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA

[0048] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0049] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0050] The CN 106 may facilitate communications with other networks For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0051] Although the WTRU is described in FIGS. 1A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0052] In representative embodiments, the other network 112 may be a WLAN.

[0053] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA The traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. The peer-to- peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad-hoc” mode of communication.

[0054] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by aparticular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0055] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0056] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two noncontiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0057] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11af and 802.11ah relative to those used in 802.11n, and 802.11ac. 802.11 af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control / Machine- Type Communications (MTC), such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g , only support for) certain and / or limited bandwidths The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0058] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802 11 n, 802.11ac, 802.11af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode) transmitting to the AP, all available frequency bands may be considered busy even though a majority of the available frequency bands remains idle.

[0059] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0060] FIG. 1 D is a system diagram illustrating the RAN 104 and the GN 106 according to an embodiment. As noted above, the RAN 104 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0061] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0062] The 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 OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing a varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0063] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non- standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b,102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0064] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, DC, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0065] The CN 106 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0066] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of non-access stratum (NAS) signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, and the like The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0067] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 106 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 106 via an N4 interface. 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 address, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0068] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets,enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, and the like.

[0069] The ON 106 may facilitate communications with other networks For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local DN 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0070] In view of FIGs. 1A-1 D, and the corresponding description of FIGs. 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0071] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, 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. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network The emulation device may be directly coupled to another device for purposes of testing and / or performing testing using over-the-air wireless communications.

[0072] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0073] The following abbreviations and acronyms may be referred to:ACK AcknowledgementBLER Block Error RateBWP Bandwidth PartCAP Channel Access PriorityCAPC Channel access priority classCCA Canonical Correlation Analysis CCE Control Channel Element CE Control Element CG Configured grant or cell group CP Cyclic Prefix CP-OFDM Conventional OFDM (relying on cyclic prefix) CQI Channel Quality Indicator CRC Cyclic Redundancy Check CSI Channel State Information CW Contention Window CWS Contention Window Size CO Channel Occupancy DAI Downlink Assignment Index DC I Downlink Control Information DFI Downlink feedback information DG Dynamic grant DL Downlink DMRS Demodulation Reference Signal DRB Data Radio Bearer eLAA enhanced Licensed Assisted Access FeLAA Further enhanced Licensed Assisted Access HARQ Hybrid Automatic Repeat Request LAA License Assisted Access LBT Listen-Before-T alk LTE Long Term Evolution e.g. from 3GPP LTE R8 and up NACK Negative ACK MCS Modulation and Coding Scheme MIMO Multiple Input Multiple Output NR New Radio OFDM Orthogonal Frequency-Division Multiplexing PHY Physical Layer PID Process ID PO Paging Occasion PRACH Physical Random Access Channel PSS Primary Synchronization Signal RA Random Access (or procedure) RACH Random Access Channel RAR Random Access Response RCU Radio access network Central Unit RE Resource Element RF Radio Front end RLF Radio Link Failure RLM Radio Link Monitoring RNTI Radio Network Identifier RO RACH occasion RRC Radio Resource Control RRM Radio Resource Management RS Reference Signal RSRP Reference Signal Received Power RSSI Received Signal Strength Indicator SDU Service Data Unit SRS Sounding Reference Signal SS Synchronization Signal SSS Secondary Synchronization SignalSWG Switching Gap (in a self-contained subframe)SPS Semi-persistent schedulingSUL Supplemental UplinkTB Transport BlockTBS T ransport Block SizeTRP Transmission / Reception PointTSC Time-sensitive communicationsTSN Time-sensitive networkingUE User EquipmentUL UplinkURLLC Ultra-Reliable and Low Latency CommunicationsWBWP Wide Bandwidth PartWTRU Wireless Transmit / Receive UnitWLAN Wireless Local Area Network

[0074] Machine learning may refer to the algorithms that solve a problem based on learning through experience (e.g., “data"), without explicitly being programmed (e.g , “configuring set of rules"). Machine learning may be considered a subset of Al. Different machine learning paradigms may be envisioned based on the nature of data or feedback available to the learning algorithm. For example, a supervised learning approach may involve learning a function that maps input to an output based on labeled training example, where each training example may be a pair comprising of an input and the corresponding output. For example, an unsupervised learning approach may involve detecting patterns in the data with no pre-existing labels. For example, a reinforcement learning approach may involve performing a sequence of actions in an environment to maximize the cumulative reward. In some embodiments, it may be possible to apply machine learning algorithms using a combination or interpolation of the above-mentioned approaches For example, a semisupervised learning approach may use a combination of a small amount of labeled data with a large amount of unlabeled data during training. Semi-supervised learning falls between unsupervised learning (with no labeled training data) and supervised learning (with only labeled training data).

[0075] Deep learning may refer to a class of machine learning algorithms that employ artificial neural networks, such as Deep Neural Networks (DNNs) . DNNs are a special class of machine learning models inspired by the human brain where the input is linearly transformed and passed-through non-linear activation function multiple times. DNNs typically consists of multiple layers where each layer consists of linear transformation and a given non-linear activation functions. The DNNs can be trained using the training data via back-propagation algorithm. DNNs have shown state-of-the-art performance in variety of domains, including speech, vision, natural language and for various machine learning settings supervised, un-supervised, and semi-supervised. The term AI / ML based methods may refer to the realization of behaviors and / or conformance to requirements by learning based on data, without explicit configuration of sequence of steps of actions. Such methods may enable learning complex behaviors which might be difficult to specify and / or implement when using legacy methods.

[0076] Factor analysis techniques are prominent in machine learning, data analytics and signal processing communities. For instance, principal component analysis (PCA), coupled matrix factorization (CMF),independent component analysis (ICA), canonical correlation analysis (CCA), are widely used in compression, dimensionality reduction, visualization, and subspace estimation,. These techniques are all operating in an unsupervised manner but under different objectives, depending on the application Some of these tools extract latent components from one data view / matrix (e.g., PCA, ICA), while others aim to recover latent common information from multiple data views / matrices (e.g., CMF, CCA).

[0077] Canonical correlation analysis (CCA) is a machine learning technique that is widely used in different fields, including machine learning and signal processing. CCA is a multiview analysis technique that seeks to discover latent common information between two data views. While single-view analysis techniques, like PCA, aim at extracting strong components from the given data matrix, multi-view analysis tools such as CCA seek to jointly analyze different views of the data. From an optimization perspective, CCA is based on a “differential” criterion that forces it to zoom in only on what is common between the different views. If one of the views includes a very strong component that is absent from the other view, CCA can ignore principal components no matter how strong they are, as long as they are not common. CCA may operate in either a linear fashion (referred to as linear CCA) or a non-linear fashion (referred to as Kernel CCA (KCCA).deep CCA (DCCA), or non-linear CCA) The main difference is that in linear CCA, the objective is to extract the latent common features through finding two linear projections of the given two data views, while in the non-linear case, the projections can be generally non-linear (e g., based on DNN).

[0078] In its simplest form, CCA seeks to find two vectors qtG CWrand q2G Cw>' (known as CCA canonical vectors and will referred to as CCA combiners in this disclosure) such that the resulting N- dimensional components from the two linear projections Y^q1G <CNand Y2q2 ^Nare maximally correlated, where YrG C ^^and Y2G CNr x Nare two given data views. In an optimization framework, the CCA formulation is given as,

[0079] where the scaling constraints serve to exclude all zero and meaningless embodiments. In addition, the CCA correlation coefficient is defined as: p = Re^Y^qJ where Re{x} indicates the real part of a given complex vector x. Problem (1) admits a simple algebraic embodiment via eigenvalue decomposition. In particular, the overall complexity requires solving for a principal eigenvector of a matrix that involves multiplication of auto- and cross-covariance matrices.

[0080] Coherent demodulation of signals transmitted over the radio interface typically requires knowledge of the (precoded / effective) wireless channel. Channel estimation process at the receiver in NR relies on the transmission of physical channels accompanied with demodulation reference signals (DMRS). DMRSs are generated using pseudo-random sequences based on systems parameters known to the receiver. The parameters used to control the sequence generation include scrambling identity, symbol locations, number ofOFDM symbols in a slot, etc. The DMRS operation in NR includes several predefined options for patterns (uniform / equally spaced) and densities of RSs based on the physical channels, configured using scheduling (DCI-based) and high-layer configuration to cater for different use cases and WTRU capabilities.

[0081] The configuration of the DMRS can include density and pattern in the resource grid, duration, starting symbol (e.g., front-loaded DMRS), and cover codes, to differentiate between antenna ports sharing the same time / frequency resources (for single-user and multi-user MIMO cases). The set of parameters for DMRS can be different depending on the physical channel and depending on WTRU capability (e.g., for PDSCH DMRS, there are Configuration Type 1 or Type 2, Mapping Type A or Type B, Starting Symbol for Mapping Type A, Single versus Double Symbol DMRS, DMRS Additional Positions, and Duration). It may also be possible to group DMRS over several resource blocks where the precoder is constant such the receiver can perform wideband channel estimation.

[0082] The specific selection of DMRS may be carried out by both higher-layer configuration and dynamic (DCI-based) signaling, but also there may be cases where there is a default configuration in place. FIGS. 2A- D illustrates an example of a DMRS pattern over one symbol and one resource block in NR with Configuration Type 1 , Mapping Type A, and Starting Symbol 3, using downlink antenna ports 1000-1003, with CDM grouping across the frequency and code domains. Upon selection of DMRS settings, the base station signals the selection to the terminal. The base station may signal the selection via RRC, MAC-CE, or PDCCH / DCI.

[0083] The terminal then utilizes the DMRS for channel estimation and coherent demodulation of the corresponding physical channels. This is achieved through specific receiver filter implementation (e.g., Least Squares, Minimum Mean Squared Error (MMSE), etc.) which broadly estimates the composite channel by mapping the transmitted layers onto the receive antennas for the resource blocks that are scheduled.

[0084] FIG. 3 is a diagram illustrating DMRS based channel estimation and equalization process. As shown in FIG. 3, at 302, the receiver may first determines the estimates of the channels of the DMRS symbols from their known locations in the received slots, where typically an averaging window is used to minimize the effects of noise. At 304, the receiver may perform multi-dimensional interpolation and extrapolation operations are then used the results to estimate the missing values associated with all the other REs from the channel estimation grid. At 306, the receiver may perform noise power estimation to improve performance by comparison of direct and average channel estimates. At 308, the terminal may, with the channel and noise estimates, design an equalizer (e.g., MMSE) followed by coherent OFDM demodulation of precoded / beamformed physical channels.

[0085] Channel estimation is needed in conventional approaches to equalize and demodulate the data channels The effective (or precoded) channel response experienced by the receiver is estimated by mobile terminals using DMRS. This information is then used for equalization and demodulation The performance of the equalization process and, ultimately, the channel / link performance may be directly influenced by the quality of the channel estimate. To achieve satisfactory channel estimation performance, a significant number ofDM RS symbols are required, which leads to a high DM RS overhead and a reduction in spectral efficiency. The RS overhead may be decreased by reducing the number of DMRS symbols. However system performance may suffer due to poor channel estimation performance. Moreover, the DMRS signals across various layers / users must be orthogonal for multi-layer transmissions (SU- or MU-MIMO). This further increases the DMRS overhead, especially as the number of layers / co-scheduled users increases.

[0086] Additionally, the implementation complexity for such approaches is high, as channel estimators require additional processing blocks such as: noise estimators, Doppler estimators, as well as interpolation & extrapolation to all REs in the allocated channel. Any loss of orthogonality of the DMRS results in poor channel estimation performance, and ultimately degrades the system performance.

[0087] The below descriptions leverage space diversity to enable DMRS free equalization using CCA. The below descriptions addresses at least the following problems: (1) how to enable efficient multilayer and / or multiuser transmission under the proposed DMRS free approach (i e., space CCA); (2) how to determine the space CCA parameters for optimized CCA performance; (3) how to enable dual modulation transmission under the proposed framework; and (4) how to determine the appropriate PDSCH mode of operation (e.g., with or without DMRS), and how to enable dynamic operation of different PDSCH modes.

[0088] The below described embodiments introduce a data channel structure that enables DMRS free equalization, and describe procedures for a mobile terminal (e.g., WTRU, UE, STA, etc.) to determine and / or report one or more aspects associated with the transmission and reception of a DMRS-free data channel

[0089] CCA may require two data views for proper operation. A CCA view may be defined as a multiantenna reception of a signal including a group of data REs in the time-frequency grid with some characteristics (e g., enforced structure). The number of REs in the two CCA views may be the same.

[0090] Time / frequency CCA may employ data (e.g., symbol or sample) repetition either in time or frequency or both. The WTRU may form the two views either in time or frequency depending on the repetition type. Most symbols (except phase RS) do not carry RS, but instead carry data. Each of the two groups of light blue REs forms a CCA view that will be used at the receiver for finding the equalizer / combiner without channel estimation. The terms “time / frequency CCA and “regular CCA” may be used interchangeably.

[0091] FIG. 4A illustrates an example of a DMRS-based PDSCH, where the DMRS configuration pattern uses DMRS Configuration Type 1, Mapping Type A, and has DMRS length of 2.

[0092] FIG. 4B illustrates an example of a regular CCA PDSCH data structure, where the regular CCA PDSCH data assumes a repetition of some of the data symbols in each RB where the repetition may occur in time or frequency. The example in FIG. 4B illustrates a repetition in time where the data symbols in OFDM symbols 2 and 3 are copied to OFDM symbols 10 and 11 .

[0093] Space CCA repetition may come naturally due to space diversity The WTRU may form the two CCA views in the receive antenna domain by grouping two non-overlapping / disjoint subsets of receive antenna ports to form the two views, assuming that the receiver has at least two receive antennas.

[0094] FIG. 4C illustrates an example of a space CCA PDSCH data structure, where the space CCA PDSCH data structure contains a special region 402 (referred to as space CCA region). The symbols within region 402 may have some properties (e.g., follow a particular power allocation distribution of the transmitted / multiplexed layers).

[0095] In a space CCA region, the time-frequency region may contain the REs corresponding to the CCA views formed by the WTRU. In space CCA case, the views are formed in the receive antenna domain. An example showing the space CCA region is illustrated in the area bounded by the red rectangle in FIG. 4C.

[0096] The dominant layer may be the layer with the highest allocated power and / or REs density in its assigned space CCA region (e.g., in case of overlap).

[0097] PDSCH mode / format may refer to a PDSCH with a specific data structure. For example, the PDSCH mode can be DM RS, regular CCA, space CCA. The terms PDSCH mode and format may be used interchangeably.

[0098] PDSCH with space CCA transmission may refers to the PDSCH transmission mode with the DMRS free data structure and with one or more space CCA region(s) included in the transmission. For example, the data structure shown in FIG 4C.

[0099] Potential benefits of the proposed PDSCH with space CCA transmission and processing may include, among other things, performance gains, complexity reduction, robustness to interferences, power consumption, and recovery guarantees.

[0100] A benefit of the proposed PDSCH with space CCA transmission and processing may include performance gains. Space CCA may provide higher performance (e g., throughput) gains relative to the legacy approach (DMRS based).

[0101] A benefit of the proposed PDSCH with space CCA transmission and processing may include complexity reduction. Space CCA may reduce the WTRU complexity since space CCA merely requires solving one or more SVD problems to get the desired signal(s) without channel or noise estimation

[0102] A benefit of the proposed PDSCH with space CCA transmission and processing may include robustness to interference. Space CCA implicitly accounts for any unknown and / or intermittent interference. The CCA combiners / equalizers are capable of projecting away any interference as long as the interference is different across the two CCA view.

[0103] A benefit of the proposed PDSCH with space CCA transmission and processing may include power consumption and robustness to high noise. Space CCA may provide performance gains at the low SNR regions, and therefore, may reduce the power consumption at the transmitter side.

[0104] A benefit of the proposed PDSCH with space CCA transmission and processing may include recovery guarantees. Different from legacy methods performance that are impacted by channel and noise estimation performance, space CCA may provide signal recovery guarantees without any knowledge of the channel.

[0105] FIG. 5 illustrates an example of a PDSCH format with space CCA transmission. REs 502 represent normal PDSCH data REs. REs 504a and 504b represents the CCA phase correction RS symbols. REs 506a to 506j represent PDSCH data symbols with some characteristics / enforced structure. Space CCA region 510 represents the space CCA region. As shown in FIG 5, space CCA region 510 include REs 504a and 504c and REs 506a to 506j. Overlapping region 512 represents the overlapping region between multiple MIMO layers within the space CCA region with predefined power variations between the MIMO layers transmitted in the overlapping region. As shown in FIG. 5, the overlapping region 512 includes REs 506e, 506f, 506g, 506h, 506i, and 506j.

[0106] The embodiments described herein are applicable to any physical channel with space CCA transmission. Different from the traditional physical channels that includes DMRS for effective / precoded channel estimation, the below described data structure with space CCA transmission is free from DMRS a WTRU may be configured with parameters to enable the physical channel with space CCA transmission, where the parameters may be signaled or indicated to the WTRU via a DCI format, RRC or MAC CE. The configuration parameters may include one or more of the following:

[0107] The configuration parameters may include transmission mode / format The transmission mode / format parameter may be used to differentiate between the different transmission formats. The transmission mode / format parameter may indicate to the WTRU the transmission mode / format (e g., from the perspective of space CCA transmission or DMRS transmission) for proper decoding. The transmission mode may include at least one of a legacy (e.g., DMRS) and / or space CCA.

[0108] The configuration parameters may include space CCA region(s) parameters The space CCA region parameters may include region boundary / geometry, which may indicate each space CCA region boundary information.

[0109] Space CCA region boundary information may be indicated through a direct indication of each space CCA region boundary. The configuration may include a starting RE index and ending RE index, where each index may be signaled using two indices, one for the subcarrier index and another for the OFDM symbol index. The configuration may also include a number of REs for space CCA transmission within a space CCA region, frequency span / space CCA subband size that indicates how many RBs each space CCA region is spanning; frequency density within the space CCA region which may indicate the REs density of the dominant layer in the space CCA region (e.g., every N subcarriers, even, odd, etc.); time span, which may indicate the time width of each space CCA region; and / or time density within the space CCA region, which may indicate the REs density in time (e.g., every OFDM symbol in the space CCA region).

[0110] The space CCA region boundary information may also be indicated by mapping between different layer(s) and format(s). For example, the WTRU may be configured with a defined mapping between the number of layers and the associated number and locations of CCA regions per layer, where each configured layer has a predefined mapping to a space CCA region.

[0111] In one embodiment, a WTRU may be configured with one or more layers transmitted through a physical channel with space CCA transmission. In an example, the WTRU may be configured with a layerspecific space CCA parameters, where the layer-specific configuration includes one or more space CCA regions characterized by the region parameters (e.g., region boundary / geometry) as described above. The WTRU may assume that the space CCA regions are non-overlapping, where the different sets of the RE indices associated with the different space CCA regions are disjoint.

[0112] A WTRU may be configured with one or more parameters associated with the multilayer transmission in each space CCA region. Outside any of the space CCA regions (e.g., REs 502 in FIG. 5), all the layers may be multiplexed and transmitted under normal operation, probably with equal power allocation across all configured layers. On the other side, in any of the space CCA region, the multilayer transmission is done in a different way to ensure proper CCA operation.

[0113] The configuration parameters may include a dominant layer parameter. Each space CCA region may have one dominant layer. The dominant layer may have a higher allocated power in its assigned space CCA region relative to the other transmitted layer(s) within the space CCA region, if any. The dominant layer may have a higher RE density in the assigned space CCA region. The dominant layer parameters may include the dominant layer index associated with each space CCA region.

[0114] The configuration parameters may include a multilayer multiplexing mode in the space CCA region. The mode may indicate whether multiple layers are transmitted in the space CCA region or only the dominant layer. If not indicated, the WTRU may assume that the default mode is the non-overlapping layers in the space CCA region (i.e., only the dominant layer is transmitted in its assigned space CCA region, and the other layers are off).

[0115] In one embodiment, to improve the transmission rate, a WTRU may be configured with multilayer transmission within the space CCA region. Along with the dominant layer that spans the entire CCA region, the WTRU may be configured with one or more overlapping layers in some subregions of the space CCA region.

[0116] As described above, FIG. 5 illustrates an example PDSCH format with space CCA transmission with overlapping layers in the space CCA region, where the dominant layer spans the all of the REs 502a to 502i which are bounded by lines 510a to 510c Overlapping layer 512 spans the REs 506e to 506j. A WTRU may be configured with one or more of the following parameters associated with the overlapping regions:

[0117] A WTRU may be configured with a default / initial %a;. The WTRU may be configured with one or more default / initial overlap between the dominant layer and the other transmitted layers.

[0118] A WTRU may be configured with region boundary / geometry. The region boundary / geometry configuration may include the starting and ending RE indices of the overlapping layer, or may be a granular overlap configuration. For example, a set of possible overlap formats where each format has its defined parameters (e.g., starting RE, size of the region and density).

[0119] A WTRU may be configured with overlapping layer indices.

[0120] A WTRU may be configured with phase symbols information, which may indicate the phase symbol locations within the overlapping region. In an embodiment, the phase symbols may be commonly used for all layers in the overlapping region.

[0121] Different from the DMRS based data structure, the proposed data structure described herein operates in a DMRS free environment, but requires appropriate processing (e.g., using CCA) at the receiver side. An embodiment may leverage space / receive diversity (i.e., reception of the same signal over multiple receive channels / antennas, coupled with CCA processing for recovering the desired signals without channel or noise estimation).

[0122] FIG. 6, illustrates an exemplary PDSCH format with a space CCA transmission. As shown in FIG. 6, REs 604a, 604b, and 606a to 606j represent the transmitted REs. The received signal corresponding to the transmitted data REs (i e., REs 604a, 604b, and 606a to 606j), denoted as e CN, may be expressed as:Y = hxT+ W where Y e cNr X Nis the received multi-antenna signal at the receiver, h e CNris the effective / precoded channel and h e CNrdenotes the noise term. The parameter N may define the CCA view length / density, For example, in FIG. 6, N = 12. Hereinafter, N may be referred to as the CCA view length or density. To enable CCA processing, two CCA views may be created by constructing two signal / data views from different / disjoint sets of receive antenna ports, where the two sets may have different number of non-overlapping receive antenna ports. For example,; one signal may be from the first half of receive antennas and the second signal may be from the second half of receive antennas. Thus, the two CCA views may be expressed as:Yt= hlxT+ W1 :Y2= h2xr+ W2

[0123] where Yte CNrl'x Nis the signal associated with the t-th CCA view, for i — 1,2 and WLis the noise term associated with each set of receive antenna ports. The effective channel may be different across the two views because the two sets are disjointed. Solving the CCA problem defined above, using the two constructed views, it can be shown that the desired signal, x, may be recovered up to complex scaling ambiguity that can be resolved using a few phase symbols, which include REs 606a and 606b. Furthermore, the resulting CCA equalizers / combiners from (i.e., qtand q2), may be used to combine the received signal in the remaining parts of the received physical channel.

[0124] One or more embodiments herein are described for any physical channel with space CCA transmission. For example, physical channels may include PDSCH, PUSCH, PUCCH, PDCCH, PBCH, PRACH or any side link channels. For example, some embodiments may be described with PDSCH as example realization, but the embodiments are equally applicable to any other physical channel For example, some embodiments may be described with WTRU as receiver of space CCA transmission, but the embodiments are equally applicable for the case of WTRU as a transmitter of space CCA transmission.

[0125] The embodiments described herein may be applicable to the physical channels (e.g., PDSCH) with space CCA transmission. Different from the traditional physical channels (e.g., PDSCH) that includes DMRSfor effective / precoded channel estimation and noise estimation, the proposed physical channel (e.g., PDSCH) is free from DMRS but adds some characteristics (e.g., enforced structure) to a group of data REs that will be leveraged at the receiver to enable DMRS free decoding of the physical channel (e.g., PDSCH). The terms PDSCH with space CCA transmission and / or space CCA PDSCH may be used interchangeably to denote the described PDSCH format

[0126] The described space CCA PDSCH format may reduce the RS overhead relative to existing PDSCH (i.e., DMRS based) while achieving better decoding performance. The space CCA PDSCH format may provide significant reduction in complexity since the enforced structure will be directly used to decode the PDSCH without the need of channel estimation and noise estimation.

[0127] Legacy PDSCH (i.e., DMRS) requires orthogonal DMRS sequences for transmitted MIMO layers across all WTRUs. The space CCA PDSCH may require less restrictive constraint to support multilayer transmission. In particular, to support multilayer layer transmission with minimal overhead, the space CCA PDSCH format simply requires partial overlap and power allocations between the configured MIMO layers in each space CCA region (i.e , region bounded by the lines 910a, 910b, and 910c in FIG. 9).

[0128] The embodiments described herein are applicable to any physical channel with space CCA transmission. Different from the traditional physical channels that includes DMRS for effective / precoded channel estimation, the below described data structure with space CCA transmission is free from DMRS a WTRU may be configured with parameters to enable the physical channel with space CCA transmission, where the parameters may be signaled or indicated to the WTRU via a DCI format, RRC or MAC CE. The configuration parameters may include one or more of the following:

[0129] The configuration parameters may include transmission mode / format The transmission mode / format parameter may be used to differentiate between the different transmission formats. The transmission mode / format parameter may indicate to the WTRU the transmission mode / format (e g., from the perspective of space CCA transmission or DMRS transmission) for proper decoding. The transmission mode may include at least one of a legacy (e.g., DMRS) and / or space CCA.

[0130] The configuration parameters may include space CCA region(s) parameters The space CCA region parameters may include region boundary / geometry, which may indicate each space CCA region boundary information.

[0131] Space CCA region boundary information may be indicated through a direct indication of each space CCA region boundary. The configuration may include a starting RE index and ending RE index, where each index may be signaled using two indices, one for the subcarrier index and another for the OFDM symbol index. The configuration may also include a number of REs for space CCA transmission within a space CCA region, frequency span which may indicate the space CCA subband size that indicates how many RBs each space CCA region is spanning; frequency density within the space CCA region which may indicate the REs density of the dominant layer in the space CCA region (e.g., every N subcarriers, even, odd, etc.); time span, whichmay indicate the time width of each space CCA region; and / or time density within the space CCA region, which may indicate the REs density in time (e.g. , every OFDM symbol in the space CCA region).

[0132] The space CCA region boundary information may also be indicated by mapping between different layer(s) and format(s). For example, the WTRU may be configured with a defined mapping between the number of layers and the associated number and locations of CCA regions per layer, where each configured layer has a predefined mapping to a space CCA region.

[0133] In one embodiment, a WTRU may be configured with one or more layers transmitted through a physical channel with space CCA transmission. In an example, the WTRU may be configured with a layerspecific space CCA parameters, where the layer-specific configuration includes one or more space CCA regions characterized by the region parameters (e.g., region boundary / geometry) as described above. The WTRU may assume that the space CCA regions are non-overlapping, where the different sets of the RE indices associated with the different space CCA regions are disjoint.

[0134] A WTRU may be configured with one or more parameters associated with the multilayer transmission in each space CCA region. Outside any of the space CCA regions (e.g., REs 502 in FIG. 5), all the layers may be multiplexed and transmitted under normal operation, probably with equal power allocation across all configured layers. On the other side, in any of the space CCA region, the multilayer transmission is done in a different way to ensure proper CCA operation.

[0135] The configuration parameters may include a dominant layer parameter. Each space CCA region may have one dominant layer. The dominant layer may have a higher allocated power in its assigned space CCA region relative to the other transmitted layer(s) within the space CCA region, if any. The dominant layer may have a higher RE density in the assigned space CCA region. The dominant layer parameters may include the dominant layer index associated with each space CCA region.

[0136] The configuration parameters may include a multilayer multiplexing mode in the space CCA region. The mode may indicate whether multiple layers are transmitted in the space CCA region or only the dominant layer. If not indicated, the WTRU may assume that the default mode is the non-overlapping layers in the space CCA region (i.e., only the dominant layer is transmitted in its assigned space CCA region, and the other layers are off).

[0137] In one embodiment, to improve the transmission rate, a WTRU may be configured with multilayer transmission within the space CCA region. Along with the dominant layer that spans the entire CCA region, the WTRU may be configured with one or more overlapping layers in some subregions of the space CCA region.

[0138] As described above, FIG. 5 illustrates an example PDSCH format with space CCA transmission with overlapping layers in the space CCA region, where the dominant layer spans REs 502a to 502i, which are bounded by lines 510a to 510c. Overlapping layer 512 spans REs 506e to 506], A WTRU may be configured with one or more of the following parameters associated with the overlapping regions:

[0139] A WTRU may be configured with a default / initial overlapping ratio ° / oaj . The WTRU may be configured with one or more default / initial overlap between the dominant layer and the other transmitted layers.

[0140] A WTRU may be configured with region boundary / geometry. The region boundary / geometry configuration may include the starting and ending RE indices of the overlapping layer, or may be a granular overlap configuration. For example, a set of possible overlap formats where each format has its defined parameters (e.g., starting RE, size of the region and density).

[0141] A WTRU may be configured with overlapping layer indices.

[0142] A WTRU may be configured with phase symbols information, which may indicate the phase symbol locations within the overlapping region. In an embodiment, the phase symbols may be commonly used for all layers in the overlapping region.

[0143] In an embodiment, the WTRU may be configured to, indicated to process, and / or decode a space CCA PDSCH (e.g , a field in DCI to indicate the new PDSCH format with space CCA transmission). Upon receiving the configuration associated with the one or more configured space CCA regions, the WTRU may process and / or decode the received PDSCH with space CCA transmission as follows:

[0144] First, the WTRU may construct the two space CCA views in each configured space CCA region (as described above), where one view is constructed from a first set of receive antenna elements and a second view is constructed from a second set of receive antenna elements. The two sets of receive antenna elements may be disjoint / non-overlapping. Next, the WTRU may derive a first CCA-based equalizers / combiners associated with the dominant layer in its assigned space CCA region.

[0145] Then, the WTRU may apply the first space CCA equalizers for decoding the REs associated with the dominant layer in the assigned space CCA region and the surrounding data REs associated with the first layer. In another embodiment, the WTRU may derive additional CCA-based equalizer(s) / combiner(s) for each additional overlapping layer(s) in the space CCA region to be used for decoding the REs associated with the overlapping layer(s) in any of the space CCA regions. In another option, the additional equalizer(s) may be used to compute interference related measurements associated with the overlapping layers.

[0146] In an embodiment, a WTRU may be configured to indicate space CCA feedback parameters associated with the decoding performance of the PDSCH with space CCA transmission. In an example, the parameters may include a performance indicator of the quality of the decoding. For example, the WTRU may be configured to indicate the CCA correlation performance associated with each dominant layer in its assigned space CCA region In another embodiment, the WTRU may be configured to indicate the CCA correlation only if the measured correlation is below a certain configured CCA correlation threshold. The WTRU may indicate the feedback parameters in a UCI field or using PUSCH set of configured resources or as part of the HARQ (ACK / NACK) reporting.

[0147] The principles described herein for space CCA based PDSCH transmission may be applied to PUSCH transmissions. The WTRU may be configured with one or more parameters for UL space CCA transmission in a PUSCH.

[0148] The parameters for UL space CCA transmission in a PUSCH may include a PUSCH format / mode, including space CCA and / or DMRS.

[0149] The parameters for an UL space CCA transmission in PUSCH may include a layer-specific space CCA region configuration. The layer-specific space CCA region configuration may be predefined (i.e., func(number of layers)). The layer-specific space CCA region configuration may be based on a mapping between (one or more) view formats(s) and layer(s). The layer-specific space CCA region configuration may be based on a geometry / boundaries per layer configuration for RE groups (e.g. , starting RE, size of the region and density). The layer-specific space CCA region configuration may be based on a dominant layer index that indicates the Ml MO layer index with the higher power and RE density within the assigned space CCA region. The layer-specific space CCA region configuration may be based on a time density (additional position in time in case of multiple CCA regions per layer in time). The layer-specific space CCA region configuration may be based on a frequency density (additional position in frequency (e.g., every N RBs)).

[0150] The parameters for an UL space CCA transmission on a PUSCH may include a configured overlap a% between layers, where, for each dominant layer, the overlap configuration may be a predefined configuration (i.e., func(number of layers and % of overlap)). The overlap configuration may also be a granular overlap configuration with a set of possible predefined overlap formats, where each format may be described as, for example, starting RE, size of the region, and / or density.

[0151] The parameters for UL space CCA transmission on a PUSCH may include a CCA phase correction reference symbol format (e.g., number, locations, modulation order) within the space CCA region.

[0152] In an embodiment, a WTRU may be configured to transmit a space CCA on a PUSCH based on an indication from the network For example, the WTRU may be configured with a space CCA configuration in RRC signaling. Subsequently the WTRU may be indicated to perform space CCA transmission on a PUSCH based on implicit or explicit indication in DCI carrying in UL grant For example, a specific DCI format may be defined for UL grants associated with space CCA transmission. In another example, a WTRU may determine that a UL grant is associated with a space CCA transmission based on presence / absence and / or values of fields in the DCI. For example, those fields may be associated with or indicate space CCA transmission.

[0153] In another example, the WTRU may determine that space CCA should be applied to an UL PUSCH upon receiving DCI that indicates a PUSCH format associated with space CCA transmission. In an embodiment, the WTRU may be configured with a semi-persistent UL resource with a PUSCH format associated with space CCA transmission. For example, the WTRU may be configured with space CCA parameters as part of SPS configuration.

[0154] Upon determining that the UL grant is associated with space CCA transmission, the WTRU may transmit on a PUSCH associated with space CCA transmission, where the space CCA transmission may include, for each layer, a set of symbols containing four group of REs. A first group of REs may carry data associated with a first layer. A second group of REs may carry data from both a first layer and second layer, where the transmit power difference between the first layer and second layer is greater than a threshold. A third group of REs may carry a CCA phase correction reference symbol. A fourth group of REs may carry data from both a first layer and second layer, where the transmit power for first layer may be equal to the second layer.

[0155] For example, the first three groups of REs may correspond to “space CCA region” per layer. For example, the number of REs in the second group relative to the sum of REs in the first and second groups may be less than or equal to the configured overlap a% For example, space CCA regions for different layers may be non-overlapping. For example, a field in DCI may indicate the new PDSCH format with space CCA transmission.

[0156] A WTRU may be configured with one or more parameters associated with a space CCA transmission.

[0157] The configuration associated with the space CCA transmission may include a PDSCH format / mode. The PDSCH format / mode may indicate, for example a space CCA format and / or DM RS format

[0158] The configuration associated with the space CCA transmission may include a layer-specific space CCA region configuration. The layer-specific space CCA region configuration may be predefined (i.e., func(number of layers). The layer-specific space CCA region configuration may be configured using a mapping between one or more view formats and layer. The layer-specific space CCA region configuration may be configured with geometry / boundaries, where each layer has its own configuration for the RE groups within the CCA region and the region boundary may be defined with, for example, starting RE, size of the region, and / or density. The layer-specific space CCA region configuration may be configured with a dominant layer index that indicates the Ml MO layer index with the higher power and RE density within the assigned space CCA region. The layer-specific space CCA region configuration may be configured with time density, which may be the additional position in time in case of multiple CCA regions per layer in time. The layer-specific space CCA region configuration may be configured with a frequency density, which may be an additional position in frequency (e.g., every N RBs).

[0159] The configuration associated with the space CCA transmission may also include a configured overlap a%, between layers. For each dominant layer the overlap configuration may be predefined (i.e., func(number of layers and % of overlap). The overlap configuration may also be a granular overlap configuration with a set of possible predefined overlap formats, where each format may be described as, for example starting RE, size of the region, and / or density.

[0160] The configuration may also include a CCA phase correction reference symbol format (number, locations, modulation order, etc.) within the space CCA region.

[0161] The WTRU may receive a PDSCH (e.g., in a new PDSCH format) associated with space CCA transmission. The space CCA transmission may include, for each layer, a set of symbols containing four group of REs: a first group of REs carrying data associated with a first layer; a second group of REs carrying data from both a first layer and second layer - where the transmit power difference between the first layer and second layer is greater than a threshold; a third group of REs carrying a CCA phase correction reference symbol; a fourth group of REs carrying data from both a first layer and second layer - where the transmit power for first layer may be equal to the second layer.

[0162] For example, the first three groups of REs may correspond to “space CCA region” per layer. For example, the number of REs in the second group relative to the sum of REs in the first and second groups may be less than or equal to the configured overlap a% For example, space CCA regions for different layers may be non-overlapping. For example, a field in DCI may indicate the new PDSCH format with space CCA transmission.

[0163] The WTRU may construct the two space CCA views in the receive antenna domain in each configured space CCA region (e.g., the first three groups of REs), where one view is constructed from a first set of receive antenna elements and a second view from a second set of receive antenna elements, where the two sets of receive antennas should be disjoint / non-overlapping and each of the two sets should contain at least one receive antenna element.

[0164] The WTRU may process the CCA views for decoding the first, second and fourth group of REs in a space CCA transmission and uses the third group of REs for phase correction.

[0165] The WTRU may indicate the success of decoding associated with the space CCA transmission (e g., the CCA correlation coefficient associated with the first group and second groups of REs). The indication may be in a HARQ feedback.

[0166] FIG. 7 is a flow chart illustrating an exemplary procedure 700 performed by a WTRU. At 702, a WTRU may receive a PDSCH associated with a CCA transmission, wherein the space CCA transmission includes a group of REs, including a first group, a second group, a third group, and a fourth group The first group of REs may carry data associated with a first layer. A second group of REs may carry data from the first layer and a second layer, wherein a transmit power difference between the first layer and the second layer is greater than a threshold. A third group of REs may carry a CCA phase correction reference symbol. A fourth group of REs may carry data the from the first layer and data from the second layer, where the transmit power of the first layer is equal to the transmit power of the second layer. At 704, the WTRU may construct a first space CCA view and a second space CCA view in a receive antenna domain in a space CCA region. At 706, the WTRU may decode the first group of REs, the second group of REs, and the fourth group of REs in the space CCA transmission.

[0167] In an embodiment, to further improve the transmission rate, a WTRU may be configured with multiple layers transmitted within one space CCA region For example, along with the dominant layer that spans theentire space CCA region, the WTRU may be configured with one or more overlapping layers in some subregions of the space CCA region. For example, as described above, FIG. 5 illustrates the overlapping layers in the space CCA region, where the dominant layer spans REs 506a to 506j bounded lines 510a and 510c, while another overlapping layer spans the REs 506e to 506j bounded by the rectangle 512. The degree of overlap between the dominant layer and the other layers is a key parameter that impacts the quality of the CCA equalizers.

[0168] A WTRU may be configured with one or more of the below described parameters associated with the overlapping regions:

[0169] A WTRU may be configured with a default / initial, minimum, and / or maximum overlap a%. A WTRU may be configured with the initial overlap along with the range (e.g., minimum and maximum values) of allowed overlap between layers.

[0170] A WTRU may be configured with a region boundary / geometry. This may include the starting and ending RE indices of the overlapping layer, or may be a granular overlap configuration, for example, a set of possible overlap formats where each format has its defined parameters (e.g., starting RE, size of the region, and / or density).

[0171] A WTRU may be configured with overlapping layer index. A WTRU may be configured with phase symbols information indicates the phase symbol locations within the overlapping region The phase symbols may be commonly used for all layers in the overlapping region.

[0172] A WTRU may be configured with performance metric thresholds to assist the WTRU in determining one or more parameters associated with the space CCA transmission. For example, the WTRU may be configured with a CCA based performance metric. For example, the metric may be a CCA correlation threshold (i.e., pjh, that ranges between 0 and 1), where a higher correlation implies better detection / decoding performance. The WTRU may be configured with and / or indicate a CCA correlation difference / gap between the dominant layer and the second interfering layer. In another example, the WTRU may be configured with a CCA interference metric threshold based on a correlation (e g., dominant layer correlation relative to the sum of Interfering layers Ratio (DCIR)).

[0173] A WTRU may be configured to indicate one or more parameters associated with a space CCA. The WTRU may be configured to report one or more of the space CCA parameters periodically, semi-persistently, aperiodically, or upon meeting trigger conditions. For example, the trigger condition may be that a change occurs in overlap by some percentage. The trigger condition may be based on a performance degradation relative to a preconfigured CCA performance threshold. In another embodiment, a WTRU may be configured to indicate interference measurements in the space CCA regions. For example, WTRU may be configured to indicate an interference related measurement based on the measured CCA correlation coefficient of the dominant layer and the other overlapping layers. The WTRU may indicate one or more of the CCA parameters via UCI or in a PUSCH resource transmission or in MAC CE.

[0174] A WTRU may be configured to determine the parameters necessary to specify the region of the resource grid over which the space CCA based transmission / computation need to be performed.

[0175] The CCA region may be positioned anywhere across the resource grid. The CCA region may be a set of REs enclosed and occupying all REs within a contour or a set of spread-out REs across the grid.

[0176] The position of the region may be based on the similarity information about the REs within the grid. If a majority of the REs observe a similar channel, then the CCA region may be defined to be a subset of these majority REs. For example, this may be achieved as a RE clustering framework, where REs are clustered based on some performance criterions or loss function (e.g , NMSE / SGCS of the estimated channel (e.g., using CSI-RS) values over the REs) and a subset of the largest cluster of REs may be selected as the CCA region. In another example, the CCA region may be selected by solving an optimization problem aimed at minimizing the variance between some metric over the REs (e.g. magnitude of channel values over the REs, phase of the channel, etc.) to identify the set of similar REs. Further, a subset of these similar and low variation REs may define the CCA region.

[0177] In another embodiment, the CCA region may be dependent on derived quantities related to the channel. For example, the location and spread of the CCA region may be dependent on the trade-off between Doppler (WTRU speed) and delay spread. For example, depending on the trade-off between these values, the CCA regions spread may be across rows or columns. For example, if the ratio of delay spread to Doppler is low, the spread of the CCA region may be higher across columns than across rows. Alternatively, when the ratio is high, the spread may be higher across rows than across columns.

[0178] In another embodiment, a trained ML model (for example a neural network) may take in as an input some derived metrics about the channel (e.g., Doppler, rank, delay spread and / or or any other extractible metric which indicates the information about the channel) or may take in as input the raw channel (from current or past channel estimates) to identify the set of WTRUs to be used for CCA.

[0179] As a default configuration, in absence of any explicitly defined procedure, the CCA region may be positioned towards the geometric center of the resource grid, to ensure similar variability for each RE with respect to the CCA based equalizer.

[0180] In settings where the channel changes significantly across the resource grid, multiple CCA regions may further be utilized to capture the variability for efficient equalization.

[0181] For example, in settings with high WTRU speed (e.g , high Doppler), where the variability in the CSI is high across the OFDM symbols, the multiple CCA regions may be defined where the regions are separated across different OFDM symbols. As an example, in a setting with two regions, the first region may be in the left half of the grid and the second region may be in the right half of the grid. Therefore, the equalizer obtained from these regions may be applied only to the left and the right halves, respectively, or interpolation may be leveraged.

[0182] For example, in settings with high delay spread, where the variability in the CSI is high across the frequency / sub-carriers / sub-bands / RBs, multiple CCA regions may be defined where the regions are separated across sub-carrier dimensions. For example, in a setting with two regions, the first region may be from the top half of the grid and the second region may be in the bottom half of the grid. The equalizer obtained from these regions may be applied only to the top and the bottom halves, respectively, or interpolation may be leveraged.

[0183] In an embodiment where the WTRU utilizes space CCA based equalization / combining, the WTRU may be configured to determine the position and number of phase symbols required to resolve the phase ambiguity in CCA.

[0184] The set of REs utilized as phase symbols may be within the CCA region or outside it.

[0185] In an embodiment, the number of the REs required for phase ambiguity may be modified by theWTRU based on the channel or any channel related metric.

[0186] For example, the WTRU may utilize a hand-crafted function or machine learntfunction of the channel parameters to predict and / or estimate the number of phase symbols, there location, and the modulation type associated with the phase symbols The hand crafted / machine learnt function may, for example, utilize the raw channel values or the derived metrics, for example, signal strength (RSRP, RSRQ, etc.), the SNR level, the power level associated with the entire channel or for a specific layer. Alternatively, the function may utilize the correlation coefficient associated with a given layer

[0187] In another embodiment, the number of phase symbols may be inversely proportional to the SNR. Thus, as the SNR reduces the number of phase symbols will be increased in a linear or non-linear fashion (and vice versa).

[0188] In another example, the WTRU may utilize an optimization-based formulation to explicitly optimize for the number of phase symbols, their location in the grid, and the corresponding modulation type.

[0189] In an embodiment corresponding to a multi-layer transmission, multiple non-overlapping CCA regions may be leveraged. Therefore, the methods described above for the single layer case may be directly leveraged for identifying the CCA region associated with each multi-layer case while ensuring that the nonoverlapping constraints are met.

[0190] In an embodiment to ensure non-overlapping sets the above methods may be carried out in a prioritized fashion such that the layer corresponding to the highest power is given preference by the WTRU to determine the CCA regions first. The selected CCA regions for the first layer may then be removed from the grid before the CCA regions are selected for the remaining layers.

[0191] In an embodiment, where optimization based or machine learning based embodiments are considered for identifying the CCA regions. Additional set-partitioning constraints may be introduced into the formulation to ensure that non-overlapping sets may be utilized in the optimization formulation to ensure nonoverlapping regions.

[0192] In another embodiment, different phase symbols may be utilized to solve for the phase ambiguity for each layer. As an example, the symbols corresponding to the layer with the highest power may be transmitted with the highest power, and so on for the other layers

[0193] In an embodiment, common phase symbols may be utilized across all layers.

[0194] In an embodiment, where a WTRU transmission is configured to occur over multiple layers, a WTRU may be configured to utilize an overlapping set of REs for the space CCA computation across multiple layers. To enable the WTRU to utilize an overlapping set of REs for the space CCA computation across multiple layers, the WTRU may be configured with one or more procedures for selecting the associated parameters. The WTRU may be configured to identify the section of the CCA region suitable for overlapped use across different layers, and more explicitly, to identify the number of REs and the location of REs within the CCA region for overlapped use across multiple layers.

[0195] For example, the degree of overlap may depend on the power difference between the layers as measured by the WTRU. If the power difference is large, then a large section of the CCA region may be reused across the layers.

[0196] In another example, given a specific performance criterion based on the throughput or bit error rate, the overlap may be adjusted to ensure that the performance criterions are met across each of the layers, or for a specific layer or for the dominant layer. Such computation may leverage pre-computed metrics or look up tables that relate performance criterion with the overlap.

[0197] In another example, the power associated with the symbols being transmitted within the CCA region may be adjusted across different layers. Thus, some symbols in the dominant layer (from the overlapped CCA region) may be transmitted with higher power and for other layers, the symbols from the same overlapped region may be transmitted with a lower power. The specific power level for each layer can be estimated based on the pre-computed metrics or look up tables that relate performance criterion with the power difference

[0198] The degree of overlap may be dependent on the number of symbols required for the CCA computation. For example, if a large number of symbols / REs are required to enable space CCA computation for each layer, the number of overlapped elements may be increased.

[0199] In another embodiment, a function may be built (either as machine learning based embodiment which would be trained using a variant of gradient based on non-gradient based learning strategies or may be hand designed based on observations) such that it takes, as an input, the required performance metric (e.g., BER, throughput, etc. ), the power associated with each layer, the correlation coefficient of each layer, and / or any other inputs and outputs the required degree of overlap and the optimal location of REs suitable for overlapped transmission.

[0200] In an embodiment, the WTRU may be configured to determine one or more interference related parameters associated with the reception of a space CCA PDSCH. The CCA correlation coefficient is a parameter that may be utilized to infer the interference strength on the dominant layer in its assigned spaceCCA region from the overlapping (e.g , partially overlapping) layers. The CCA correlation coefficient associated with the dominant layer may be defined as

[0201] where q^1-1and q^1-1are the CCA equalizers / combiners needed to recover the signal associated with the dominant layer in its assigned space CCA region from the two receive antenna sets, and p_1 is the corresponding correlation coefficient ranging between 0 and 1. A higher correlation may imply better recovery of the dominant layer signal in the space CCA region. For every additional overlapping (e.g., partially) layer with the dominant layer, an additional correlation coefficient may be computed as:

[0202] where q^ and q^ are the CCA combiners / equalizers associated with the i-th overlapping layer, and Pi is the corresponding correlation coefficient, for i > 1 and pi-1> p;. To ensure acceptable detection / recovery performance of the dominant layer in its assigned space CCA region, the dominant layer CCA correlation coefficient, pt, may need to be sufficiently greater than the correlation associated with the overlapping layers, p for i >1 . The WTRU may determine and / or report one or more interference related parameters based on the measured CCA correlation coefficients of the dominant layer and overlapping / interfering layers.

[0203] In an embodiment, a WTRU may be configured to or indicated to determine and / or report one of the following interference metrics:

[0204] The WTRU may be configured or indicated to determine and / or report a number of strong interferes in each space CCA region (NJ) The WTRU may count the i-th overlapping layer as strong if the associated correlation coefficient pLexceeds a certain configured threshold, for i >1. In another example, the WTRU may count the i-th overlapping layer as strong if the correlation difference pt- p,- or correlation ratio p- p is below a certain configured threshold. The WTRU may be configured to indicate W;if it exceeds a certain configured threshold, where the threshold may represent the number of configured overlapping layers within a space CCA region

[0205] The WTRU may be configured or indicated to determine and / or report interference metric based on CCA correlation. The interference metric may include one or more of the following:

[0206] The interference metric may include a dominant layer correlation relative to the sum of interfering layers ratio (DCIR), where DCIR may be defined as:where i > 1 and I is the number of interfering / overlapping layers in the space CCA region. The WTRU may be configured to measure and indicate DCIR if the measured value exceeds a certain threshold. For example, the WTRU may be configured or indicated to measure DCIR associated with a certain configured number ofinterferes (I). For example, a WTRU may be indicated to measure the interference based on the strongest interfering layer (i.e., I = 2).

[0207] The interference metric may include a correlation difference (CD) which represents the CCA correlation difference between the dominant layer and each interfering layer, where the CD may be defined as: Pd° = Pi - Pi. i> 1

[0208] The WTRU may be configured to determine and / or report the correlation difference between the dominant layer correlation coefficient and the i-th interfering layer. In an embodiment, the WTRU may be configured to report the correlation difference if it exceeds a certain configured threshold

[0209] In another embodiment, the WTRU may be configured to perform and / or report power measurements associate with the dominant layer and the overlapping layer in each space CCA region. In an example, the WTRU may report the ratio between the received power of the dominant layer and the sum of the overlapping layers powers in each space CCA region. In another example, the WTRU may be configured to report the power difference or ratio if the measured value is below a configured threshold.

[0210] A WTRU may be configured to indicate one or more parameters associated with interference measurements in one or more of the configured space CCA regions. The WTRU may indicate the interference feedback parameters upon meeting a trigger condition (e.g., DCIR exceeds a configured threshold). In another option, the WTRU may indicate one or more interference parameters based on a time event (e.g., periodic, or semi-persistent) If configured to indicate one of the parameters, the WTRU may indicate the interference parameters in a UCI field or using PUSCH set of configured resources.

[0211] A WTRU may be configured to receive space CCA transmissions based on configured space CCA parameters

[0212] In an embodiment, the WTRU may be configured to determine preferred space CCA parameters based on a preconfigured criterion. In an embodiment, different criteria may be configured for determining preferred values of different CCA parameters. The criteria may include measurements on the received space CCA transmission and / or space CCA configuration. In an embodiment, the WTRU may be configured with trigger conditions to report preferred CCA parameter. The WTRU may report one or more preferred space CCA parameters based on preconfigured trigger conditions In an embodiment, different reporting trigger conditions may be configured for different CCA parameters. The WTRU may trigger reporting of space CCA parameters when the difference between configured space CCA parameters and the preferred space CCA parameters exceed a preconfigured threshold. Different thresholds may be configured for different parameters. The thresholds may be a function of type of space CCA parameters.

[0213] The WTRU may receive space CCA transmission according to space CCA configuration. In an embodiment the Space CCA configuration may include Space CCA region configuration. Space CCA region configuration may include starting RE, size of the region, time density of REs - number of symbols within space CCA region, frequency density of REs - number of subcarriers per RB etc. The WTRU may be configured todetermine preferred space CCA region parameters - based on a preconfigured condition. For example, the WTRU may determine preferred space CCA region configuration such that the smallest space CCA region leads to lowest correlation between layers within the space CCA region. For example, the WTRU may determine preferred space CCA region configuration such that the smallest space CCA region that leads to target Bit Error Rate (BER) The WTRU may be configured to report preferred Space CCA configuration if the change in BER and / or correlation exceeds a preconfigured threshold when compared to a currently configured space CCA configuration The WTRU may be configured to report preferred Space CCA configuration if the change in space CCA region size exceeds a preconfigured threshold In an embodiment, the WTRU may be configured with n space CCA regions where each space CCA region is associated with a specific layer. The WTRU may be configured to report the preferred space region configuration per layer.

[0214] In an embodiment, the trigger for reporting space CCA parameters may be a function of overlap between layers in the space CCA region. For example, the overlap may be associated with the size of second group REs within the space CCA region. For example, in a transmission a preconfigured a group of REs (herein a second group of REs) within the space CCA region may carry data from both a first layer and a second layer, where the transmit power difference between the first layer and second layer is greater than a preconfigured threshold. The size of this group of REs may correspond to the amount of overlap between the first layer and the second layer. The WTRU may be configured with an overlap parameter (a configured overlap) for space CCA transmissions. In an embodiment, the WTRU may be configured to determine an overlap parameter (a preferred overlap) that meets a criteria. For example, the WTRU may determine a preferred overlap parameter such that the size of the second group of REs is maximized. For example, the WTRU may determine a preferred overlap parameter that maximizes the size of the second group of REs and maximizes the throughput / SNR. For example, the WTRU may determine a preferred overlap parameter that maximizes the size of the second group of REs and minimize the inter-layer interference and / or BER.

[0215] In an embodiment, the WTRU may be configured to report the size of the overlap in terms of number of REs, starting RE, time span in terms of OFDM symbols, and / or frequency space in terms of number of subcarriers per RB.

[0216] In an embodiment, the WTRU may be preconfigured with a set of overlap patterns / configurations. Each preconfigured overlap pattern may be associated with a logical ID. The WTRU may be configured to determine an overlap pattern which maximizes the throughput / SNR / SINR and / or minimize the inter-layer interference and / or BER / BLER. When the preferred overlap pattern is different from the configured overlap pattern, the WTRU may trigger a report including the space CCA parameters. In an embodiment, the WTRU may report the index to the preferred overlap pattern as part of space CCA parameters.

[0217] In an embodiment, the WTRU may be configured to report the ratio of the overlap in terms of number of REs of first layer to the second layer within the overlap region etc. In an embodiment, the ratio may be expressed as percentage. The WTRU may report the ratio or percentage of overlap when the ratio or overlap changes by a preconfigured threshold.

[0218] In one or more embodiments, the WTRU may be preconfigured with minimum and maximum overlap parameters By default, the minimum overlap parameter may be zero. The WTRU may be configured to report the overlap parameter within this preconfigured range.

[0219] In an embodiment, the WTRU may be configured to determine the difference between currently configured overlap and a preferred overlap (herein, referred to as “delta overlap”). The WTRU may be configured to determine the magnitude and the sign of the delta overlap. For example, the WTRU may determine positive delta overlap if the preferred overlap is larger than the configured overlap. For example, the WTRU may determine a negative delta overlap if the preferred overlap is smaller than the configured overlap.

[0220] The WTRU may be configured with one or more space CCA region. Within each space CCA region the WTRU may be configured with a dominant layer and n non-dominant layers. In an embodiment, the WTRU may be configured to measure received power difference between n layers in the space CCA region. In an embodiment, the WTRU may be configured to measure difference between received power in the dominant layer and sum of the received power in the remaining non-dominant layers in the space CCA region. The WTRU may be configured to measure the power difference between dominant and non-dominant layer for each configured space CCA region. In an embodiment, the WTRU may be configured to trigger reporting of space CCA parameters when the received power difference between dominant layer and sum of non-dominant layers is greater than a preconfigured threshold. In an embodiment, the WTRU may be configured to determine the power difference between the layers based on BER and / or throughput. For example, the WTRU may determine the preferred power difference that leads to the lowest BER / highest throughput for a given overlap configuration.

[0221] In an embodiment, the WTRU may be configured to report the number of strong interferers in each CCA region. In another embodiment, the WTRU may be configured to report the layer with maximum number of interferers. In another embodiment, the WTRU may be configured to report the top n layers with the highest number of interferers. The WTRU may trigger such a report when the number of strong interferers exceeds a threshold. In another embodiment, the WTRU may be configured to report DCIR per each CCA region. The WTRU may be configured to report DCIR when the DCIR exceeds a threshold. The WTRU may trigger the report when the layer with largest DCIR and / or number of interferers changes from the previous report.

[0222] In an embodiment, the WTRU may determine one or more preferred space CCA configurations as a function of measured interference within the space CCA region. In an embodiment, the WTRU may be configured to determine one or more of preferred space CCA region size, overlap ratio and power difference as a function of number of interfering layers in the space CCA region. In another embodiment, the WTRU may be configured to determine one or more of preferred space CCA region size(s), overlap ratio, and power difference as a function of DCIR and / or correlation difference between dominant layer and interfering layer in the Space CCA region. In another embodiment, the WTRU may be configured to determine one or more of a preferred space CCA parameters where the parameters may include one or more of the following: region size, an overlap ratio between the transmitted MIMO layers within a space CCA region, and / or a power differencebetween the transmitted MIMO layers within a space CCA region wherein the power difference is determined to maximize the throughput / SNR / SINR and / or minimize the inter-layer interference and / or BER and / or BLER.

[0223] In an embodiments, a WTRU may be configured to trigger a report of preferred CCA parameters based on one or more measurements associated with the space CCA region conditions or change. For example, this may include change in channel rank, change in SNR, SINR, RSRP, RSRQ, change in doppler spread, delay spread, and / or BLER.

[0224] In an embodiments, a WTRU may be configured to trigger a report of preferred CCA parameters based on one or more measurements associated with channel conditions or change thereof. For example, this may include change in channel rank, change in SNR, SINR, RSRP, RSRQ, change in doppler spread, delay spread, and / or BLER.

[0225] In an embodiment, a WTRU may be configured to report the preferred space CCA parameters periodically For example, the WTRU may be configured with periodic / semi-persistent UL resources to report space CCA parameters. The WTRU may be configured with PUCCH resources for reporting. In an embodiment, the WTRU may be configured to report preferred space CCA parameters as part of CSI feedback reporting. For example, the WTRU may include the CSI feedback in a first part of the CSI report and preferred space CCA parameters in the second part of the CSI report.

[0226] In an embodiment, a WTRU may be configured to report the preferred space CCA parameters based on one or more conditions. For example, the WTRU may be preconfigured with a set of space CCA parameters each indexed with a logical ID. The WTRU may report the preferred space CCA parameters by selection and / or indication of one of the preconfigured spaces CCA parameter from the preconfigured set. In one embodiment, the WTRU may transmit a MAC CE that carries an index to the preconfigured space CCA parameter set. In another embodiment, the WTRU may transmit a predefined codepoint in PUCCH, where the codepoint maps to one of the preconfigured Space CCA parameter set.

[0227] In an embodiment, the WTRU may be configured to report preferred Space CCA parameters as a response to explicit request from the network. For example, the WTRU may be configured with a CSI reporting format associated with space CCA parameters. For example, the WTRU may receive an aperiodic CSI report trigger from the NW. For example, as a response the WTRU may transmit the preferred Space CCA parameters In an embodiment, the aperiodic request trigger may indicate what space CCA parameters can be indicated in the report.

[0228] In an embodiment, a WTRU may be configured to report preferred space CCA parameters implicitly or explicitly as part of HARQ feedback. In an embodiment, the WTRU may be configured with space CCA aware HARQ codebook (SAHC). For example, the SAHC may include one or more HARQ feedback codepoints where each codepoint may indicate two types of information. A first type of information may indicate whether the transport block decoding was successful and a second type of information may indicate a preferred spaceCCA configuration For example, the WTRU may have SAHC codebook may have following codepoints: ACK, NACK + Space CCA paramterl , and / or NACK + Space CCA parameter .

[0229] When the decoding is successful for the transport block, the WTRU may transmit ACK. When the decoding is unsuccessful for a transport block, the WTRU may determine the codepoint based on the preferred space CCA parameter. For example, when space CCA parameterl is preferred, the WTRU may transmit the codepoint associated with NACK + Space CCA parameter!. For example, when space CCA parameter? is preferred, the WTRU may transmit the codepoint associated with NACK + Space CCA parameter?. In an embodiment, the space CCA parameterl may correspond to positive delta overlap and space CCA parameter? may correspond to negative delta overlap. This embodiment may be extended to support feedback of different space CCA parameter combinations and HARQ codebooks.

[0230] In an embodiment, the WTRU may receive configuration for space CCA parameters via RRC signaling, for example, in RRC reconfiguration, RRC setup, and / or RRC resume. In another embodiment, the WTRU may be preconfigured with a plurality of Space CCA parameter sets, each associated with logical ID. In an embodiment, the WTRU may receive a MAC CE indicating which specific Space CCA parameter to be activated or deactivated. In an embodiment, the WTRU may receive a DCI with DL grant where the DCI may indicate the space CCA parameter associated with the PDSCH transmission.

[0231] In an embodiment, plurality of PDSCH formats may be defined where each PDSCH format may be associated with specific Space CCA parameterization The WTRU may receive DCI indication for new PDSCH format where the PDSCH format may implicitly indicate the space CCA parameterization.

[0232] In an embodiment, the WTRU may be preconfigured with a default space CCA parameters. Subsequently, MAC CE based signaling or DCI based signaling may indicate delta configuration to the default space CCA parameters.

[0233] Upon receiving the space CCA based PDSCH transmission, the WTRU may determine the associated space CCA parameterization and process the received PDSCH receiving the space CCA parameter configuration and the corresponding PDSCH transmission, according to the embodiments described above. For example, the WTRU may construct the two space CCA views in each configured space CCA region, where one view is constructed from a first set of receive antenna elements and a second view from a second set of receive antenna elements, where the two sets of receive antenna elements may be disjoint / non-overlapping. Second, the WTRU may derive a first CCA-based equalizers / combiners associated with the dominant layer in its assigned space CCA region. Then, the WTRU may apply the first space CCA equalizers for decoding the REs associated with the dominant layer in the assigned space CCA region and the surrounding data REs associated with the first layer. In another embodiment, the WTRU may derive additional CCA-based equalizer(s) / combiner(s) for each additional overlapping layer(s) in the space CCA region to be used for decoding the REs associated with the overlapping layer(s) in any of the space CCA regions. The additional equalizer may be used to compute interference related measurements associated with the overlapping layers.

[0234] In an embodiment, there may be ambiguity in terms of preferred space CCA parameter indication from the WTRU. For example, when the space CCA parameter is signaled as a delta overlap, the reference space CCA parameters may be associated with previous PDSCH transmission. However, if there are transmission errors (e.g., WTRU fails to detect DCI associated with PDSCH transmission), there may be a mismatch in terms of reference space CCA parameter. In an embodiment, the WTRU may be configured to transmit delta feedback associated with a preconfigured reference transmission. For example, the reference transmission may be a hypothetical transmission with preconfigured parameters. In another example, the reference transmission may be explicitly signaled by the NW. For example, the reference transmission may be associated with a transmission for which successful ACK was received from the WTRU.

[0235] To demonstrate the impact of the space CCA parameters (e.g., overlap percentage and power difference), the BER performance is evaluated and illustrated in FIG 8, which illustrates the overlap and power difference impacts on a space CCA performance. FIG. 8 illustrates a downlink scenario with a single transmitter receiver pair. In FIG. 8, the following simulation parameters are used: number of receive antenna was set to 4, modulation scheme is BPSK, SNR was set to 10 dB, the number of CCA phase symbols was set to 2. The number of symbols in the space CCA region was set to 100. The overlap between the fi rst / dom i nant layer and the second layer is varied between 0% and 100% on the x-axis. Further, the BER performance is evaluated for different power difference values in the overlap region between the first and second layer.

[0236] As shown in FIG. 8, increasing the overlap between the dominant / first layer and the second layer in the space CCA region degrades the detection performance of the first layer for a fixed power difference value, which motivates the need of carful choice of the overlap percentage. For a fixed overlap percentage, the BER performance improves by increasing the power difference between the two layers in the overlapping region. Appropriate power control between the two layers in the overlap region may improve the system performance under the space CCA transmission.

[0237] In an embodiment, a WTRU may configured with one or more CCA configurations. Each CCA configuration may include a layer specific space CCA region configuration. The layer specific space CCA region may be predefined (e.g., func(number of layers)). The layer specific space CCA region may be configured using a mapping between one or more view formats and layers. The layer-specific space CCA region configuration may be configured with geometry / boundaries, wherein each layer has its own configuration for the RE groups within the CCA region and the region boundary may be defined with, for example, starting RE, size of the region, and / or density.

[0238] Each CCA configuration may include a default / initial, minimum, and / or maximum overlap percentage (a%) between layers. For each dominant layer, the overlap configuration may be predefined (e.g., func(number of layers and % of overlap). For each dominant layer, the overlap configuration may be configured using a granular overlap configuration, including a set of possible overlap formats for each format (e.g., starting RE, size of the region and density).

[0239] Each CCA configuration may include a performance metric threshold (e.g., CCA correlation difference / gap threshold). Each CCA configuration may include a CCA phase symbols format (e.g., number, locations, modulation order, etc.). Each CCA configuration may include space CCA feedback configuration, including triggers and UL resources.

[0240] A WTRU may receive a PDSCH associated with a space CCA configuration (e.g., a field in DCI to indicate the new PDSCH format with space CCA transmission). The space CCA transmission may include, for each layer, a set of symbols containing four group of REs: (1 ) a first group of REs carrying data associated with a first layer; (2) a second group of REs carrying data from both a first layer and second layer - where the transmit power difference between the first layer and second layer is greater than a threshold and the number of REs in the second group relative to the sum of REs in the first and second groups is less than or equal to the configured overlap percentage (a%); (3) a third group of REs carrying a CCA phase correction reference symbol; and / or (4) a fourth group of REs carrying data from both a first layer and second layer, where the transmit power for first layer may be equal to the second layer.

[0241] For example, the first three groups of REs may correspond to a space CCA region per layer. For example, the number of REs in the second group relative to the sum of REs in the first and second groups may be less than or equal to the configured overlap percentage (a%). For example, space CCA regions for different layers may be non-overlapping. For example, a field in DCI may indicate the new PDSCH format with space CCA transmission.

[0242] A WTRU may determine one or more space CCA feedback parameters based on preconfigured conditions at least in part associated with correlation and / or power difference between the layers. For example, a WTRU may determine parameters, including size, time / frequency span, permissible degree of overlap per layer or incremental overlap (+ / - 6a), overlap pattern (e.g., starting RE), phase symbols locations and number within the CCA region based on one or more of the following conditions: (1) measured CCA correlation associated with the target layer within a space CCA region (e.g., based on correlation difference between different layers transmitted within the same region) where the WTRU may increments / decrements the overlap based on the configured correlation threshold; (2) received power difference between the dominant layer and the second strongest or the sum of the remaining transmitted layers; and / or (3) measured SNR per layer in the space CCA region, channel quality metrics (e.g., L1-RSRP, RSRQ).

[0243] In one example, a WTRU may determine the number of strong interferes for the dominant layer(s) in the one or more space CCA regions based on the configured correlation threshold (e.g., based on the measured CCA correlation gap between the first component and each of the other components, e.g., count a component as a strong interferer if the associated measured gap exceeds a configured threshold)

[0244] In an example, if trigger conditions are satisfied for reporting space CCA parameters, the WTRU may transmit feedback on the preconfigured / allocated UL resources. The trigger conditions may be periodicand / or aperiodic triggers, for example, including if one or more parameters below change by a preconfigured threshold. The trigger condition may be a correlation threshold.

[0245] The feedback on the preconfigured / allocated UL resources may include overlapping information. The overlapping information may include the delta overlap (i e., a ratio of number of REs in the second group of REs relative to the sum of number of REs in the first and second groups). For example, a negative delta may provide an indication to reduce the overlap between layers (e.g., reduce number of REs in the second group). A positive delta may provide an indication to increase the overlap between layers, within the configured minimum and maximum values. Another example may be to feedback index to one of the preconfigured overlap configuration, overlap region(s) boundary (e.g., starting RE).

[0246] The feedback on the preconfigured / allocated UL resources may include the received power difference between the dominant layer and the second non-dominant or the sum of the remaining non-dominant layers in the one or more space CCA region

[0247] The feedback on the preconfigured / allocated UL resources may include space CCA region parameters (e.g., size, time / frequency span).

[0248] The feedback on the preconfigured / allocated UL resources may include interference measurements. For example, the interference measurements may indicate a strong number of interferes for each dominant layer in its assigned space CCA region. The interference measurements may include an interference metric that may be based on a correlation (e.g., dominant layer correlation relative to the sum of interfering layers ratio (DCIR)). The DCIR may assist the gNB with MU scheduling using space CCA

[0249] The WTRU may receive configuration information for the new space CCA parameters, where, for example, the configuration may include one or more of parameters described above (e.g., overlap, number of overlapping layers). The WTRU may receive PDSCH with updated CCA configuration (e.g., DCI with DL grant carries an indication of the PDSCH with new CCA format). The WTRU may process the received PDSCH with the updated space CCA configuration.

[0250] A WTRU may be configured with one or more layers transmitted through a PDSCH with space CCA transmission, where the configuration includes one or more parameters associated with the space CCA region (e g., space CCA region boundary), as defined above Because the REs associated with the dominant layer in its assigned space CCA region have special characteristics (e.g , higher density, minimal channel variations and lower interference), it may be beneficial to further improve the transmission rate within the space CCA region and the surrounding REs. In an embodiment, the WTRU may be configured with a dual modulation transmission mode, where the mode enables different transmission rates (e.g., different modulation order) within the same transmission, probably in different regions of the time-frequency resource grid. In the embodiments described herein, the dual modulation transmission mode is not only limited to change in the modulation scheme, but it may include a change in modulation scheme and / or target code rate and / or transport block size.

[0251] FIG. 9 illustrates an example dual modulation transmission mode for a space CCA based PDSCH. REs 902 represent normal PDSCH data REs. REs 904a and 904b represents the CCA phase correction RS symbols. REs 906a to 906j represent PDSCH data symbols with some characteristics / enforced structure. Space CCA region 810 represents the space CCA region. As shown in FIG. 9, space CCA region 910 include REs 904a and 904c and REs 906a to 906j. Boundary 912 represents the separation between REs transmitted with a first transmission rate and REs transmitted with a second transmission rate.

[0252] The dual modulation transmission mode configuration may include a dual modulation transmission mode parameter. One bit may indicate whether the mode is enabled or not. If not configured, the WTRU may assume that the entire transmission includes a fixed transmission rate across the entire time-frequency grid (i.e., single modulation mode).

[0253] The dual modulation transmission mode configuration may include a dual modulation boundary information parameter. The dual modulation boundary may distinguish a first set of REs transmitted with a first transmission rate from a second set of REs transmitted with a second transmission rate. The first set of REs may be referred to as a first region and the second set of REs may be referred to as a second region. In FIG. 9, the first set of REs include all the REs inside the boundary 912 and the second set of REs include all the REs outside the boundary 912.

[0254] The boundary information may include parameters. For example, the boundary information may include a space CCA region boundary flag, where one bit in the scheduling DCI indicates that the dual modulation boundary is different from the space CCA region boundary. If not configured, the WTRU may assume that the space CCA region and dual modulation boundaries are aligned. The boundary information may include boundary geometry, which may indicate the geometry of the boundary (e.g , starting RE, ending RE, predefined format signaled / configured through an index).

[0255] The dual modulation transmission mode configuration may include a dual modulation granularity parameter that indicates the level at which the dual modulation mode is used. In an embodiment, the dual modulation mode may be activated or deactivated across all layers transmitted to a specific WTRU. In an embodiment, a dual modulation mode may be used per layer across the entire time-frequency band (i.e., dual modulation mode is used for the first layer while a single modulation mode is used for the other layers). In an embodiment, a dual modulation mode may be applied on the sub-band level where the same layer may use either dual or single modulation mode in different regions of the time-frequency grid.

[0256] The dual modulation transmission mode configuration may include a performance threshold parameter, which indicates one or more performance conditions which may be used to assist the WTRU with determining the boundary information. In an example, performance threshold may be a CCA correlation coefficient associated with the detection in the first region (e.g., reduce the region size if the measured correlation is lower than the threshold). In another example, the performance threshold may indicate the allowed amount of change in the channel (e.g., based on CSI-RS) within the first region.

[0257] In another embodiment, a WTRU may be configured with another CSI quantity that defines the data transmission rate used in the first set of REs (i.e., first region) The CSI quantity associated with the first region, may be referred to precoded channel quality indicator (PCQI) or effective channel quality indicator (eCQI) and may be defined as a part of PDSCH transport block with a combination of modulation scheme, target code rate and transport block size corresponding to the PCQI index, and occupying a group of downlink physical resource blocks associated with space CCA transmission, could be received with a transport block error probability not exceeding 0.1. PCQI may be derived based on the quality of the precoded / effective channel while CQI may be based on the CSI-RS based channel. In an embodiment, PCQI may be used along with the legacy CQI, where PCQI may indicates the transmission rate in the first region while CQI is used for the second region. In an embodiment, PCQI may be used to indicate the transmission rate for both regions.

[0258] A WTRU may be configured to indicate feedback associated with a dual modulation transmission mode. For example, the WTRU may be configured to indicate the PCQI associated with one or two region(s). In an embodiment, the WTRU may be configured to indicate both CQI and PCQI associated with the two regions.

[0259] A WTRU may receive a transmission (e.g., PDSCH) or perform a transmission (e.g., PUSCH) using dual modulation mode. In dual modulation mode, a single transmission may be composed of regions, each with one or more region-specific modulation orders, or code rates, or transport block size, or code block group size, or code block size, or transmission power. A region may be defined or parameterized by at least one of: set of REs; set of subcarriers; set of symbols; set of RBs; transmission layer; Rx or Tx beam; and / or TCI state.

[0260] A dual modulation mode transmission may be configured with a set of parameters.

[0261] The set of dual modulation mode transmission parameters may include the number of regions. For example, a transmission may include one or more of: a first region that overlaps with and includes a set of CCA symbols (e.g., overlaps and includes all CCA symbols), a second region that does not overlap and does not include a set of CCA symbols (e.g., does not overlap and does not include any CCA symbols), or a third region that overlaps with and includes phase symbols (e.g., overlaps with and includes only the phase symbols). Herein, CCA symbols may be used to indicate the symbols carried by the REs in any of the space CCA region. The regions of a dual modulation mode transmission may cover all the resources of a transmission. The regions of a dual modulation mode transmission may be orthogonal to each other (i.e., the regions may not overlap in the same resources).

[0262] The set of dual modulation mode transmission parameters may include boundaries of the one or more regions. For example, two regions may be defined by a boundary where each region meet.

[0263] The set of dual modulation mode transmission parameters may include transmission parameters associated to a region. For example, each region of a transmission may be associated with a set of transmission parameters The transmission parameters may include at least one of: modulation order, code rate, transport block size, code block group size, code block size, transmission power. In a scheduling assignment, thetransmission parameters may be indicated via TBS. In a feedback report for a dual modulation mode transmission, the transmission parameters may be indicated via CSI (e.g., CQI).

[0264] The set of dual modulation mode transmission parameters may include a transmission layer. For example, a set of dual modulation mode transmission parameters may be associated to a specific transmission layer.

[0265] A WTRU may receive or transmit a first transmission using dual modulation mode. The first transmission may use a first set of parameters including at least one of: CCA symbols using a first CCA configuration, phase symbols using a first phase symbol configuration, a first set of transmission regions, a first transmission region boundary, DMRS symbols using a first DMRS configuration. The WTRU may determine a desired set of dual modulation mode parameters based on the reception of the first transmission, or measurements performed on the first transmission.

[0266] The WTRU may determine that a transmission is a first transmission (i.e., a transmission from which it may determine a desired set of dual modulation mode parameters) based on the transmission being the first in a burst.

[0267] The WTRU may determine that a transmission is a first transmission based on time. For example, the WTRU may be configured with time instances or slots, or symbols, or subframes for which a transmission may be used as a first transmission. In another example, a WTRU may be configured with, or may determine, a maximum time duration, or maximum number of slots, or maximum number of symbols, or maximum number of subframes between two first transmissions. Upon the maximum time duration elapsing or maximum number of slots / symbols / subframes being surpassed, the WTRU may consider a subsequent transmission as a first transmission.

[0268] The WTRU may determine that a transmission is a first transmission based on Indication in scheduling assignment. For example, a WTRU may be indicated in a DCI that a transmission is to be a first transmission.

[0269] The WTRU may determine that a transmission is a first transmission based on an associated measurement being above or below a threshold. For example, a WTRU may perform measurements on a transmission or resources associated with the transmission (e.g., DMRS, CCA, CSI-RS), the WTRU may determine a transmission to be a first transmission.

[0270] A WTRU may determine the performance of a first dual modulation mode transmission set of parameters from the reception of a first transmission. A WTRU may determine the performance of a first dual modulation mode transmission set of parameters from the reception of feedback associated to a transmitted first transmission.

[0271] A WTRU may determine the performance of a first dual mode transmission set of parameters based on HARQ-ACK determination. For example, the WTRU may determine one or more HARQ-ACK values per configured region.

[0272] A WTRU may determine the performance of a first dual mode transmission set of parameters based on a correlation of CCA symbols or resource elements. For example, the WTRU may determine the correlation of decoded CCA symbols or resource elements.

[0273] A WTRU may determine the performance of a first dual mode transmission set of parameters based on a DM RS measurements.

[0274] A WTRU may determine the performance of a first dual mode transmission set of parameters based on CSI-RS measurements. For example, the WTRU may determine the performance of a first set of dual modulation mode transmission parameters based on CSI-RS received in a set of resources associated with the first transmission

[0275] A WTRU may determine the performance of a first dual mode transmission set of parameters based on a determined CSI. For example, the WTRU may determine the CSI based on CCA or DMRS or CSI-RS measurements.

[0276] The WTRU may compare a performance measurement to one or more threshold(s) to determine whether the performance is above or below an acceptable level. The threshold(s) may be configurable.

[0277] A WTRU may determine a set of desired dual modulation mode parameters based on the performance of a first transmission and associated performance requirements. The performance requirements may include at least one of: BLER; CCA correlation value; rate of HARQ-NACK or HARQ-ACK; minimum, maximum or fixed CQI difference between two regions; highest throughput (e.g., the requirement may be highest throughput satisfying a BLER target; and / or minimum or maximum region size for at least one region.

[0278] The performance requirements may be determined based on the priority of a transmission For example, transmissions of a first priority may require a first CCA correlation value, and transmissions of a second priority may require a second CCA correlation value. The performance requirements may be determined based on the transmission type. For example, the requirements may depend on whether a transmission is control plane or data plane, broadcast or multi-cast or unicast. The performance requirements may be determined based on indication. For example, a WTRU may receive an indication of a performance requirement in an RRC message, or a MAC CE or a DCI.

[0279] A WTRU may determine a set of desired dual modulation mode parameters, where the set of dual modulation mode parameters is described above.

[0280] The desired set of dual modulation mode parameters may be indicated using absolute feedback for one or more regions. For example, the feedback may include absolute CQI, or Rl, or PMI for a region.

[0281] The desired set of dual modulation mode parameters may be indicated using relative feedback for one or more regions. For example, the feedback may include relative CQI, or Rl, or PMI for a region, where the value is relative to that of another region

[0282] The desired set of dual modulation mode parameters may be indicated using offset value between two regions. For example, the feedback may include an offset value for CQI between two regions. The offsetvalue may be valid for a period of time or multiple subsequent feedback reports. The WTRU may report a single value (e.g., associated to a first region) in subsequent feedback reports and the actual value for the second region may be determine from the reported value for the first region and the reported offset

[0283] The desired set of dual modulation mode parameters may be indicated using transmission of a performance metric. For example, the WTRU may report a performance metric (e.g., CCA correlation) and may report a first parameter value associated to a first region. The WTRU may determine whether to report a first parameter value associated to a second region as a function of the performance metric value

[0284] The WTRU may be provided resources to report a desired set of dual modulation transmission parameters The WTRU may be configured to report desired sets of dual modulation transmission parameters periodically In another method, the WTRU may determine when to report a set of dual modulation transmission parameters

[0285] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on Change from a previous reported set of dual modulation transmission parameters. For example, if the WTRU determines that the desired set of regions or boundaries has changed compared to a previously reported set of regions of boundaries, the WTRU may report a new desired set of dual modulation transmission parameters.

[0286] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on a performance metric value determined from a first transmission using a first set of dual modulation transmission parameters. For example, if a performance falls below a performance requirement (e g., by a threshold value), the WTRU may be triggered to report a new desired set of dual modulation transmission parameter.

[0287] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on a performance metric value determined from multiple transmissions using one or more sets of dual modulation transmission parameters. For example, the WTRU may determine the HARQ-NACK rate and if it goes above a threshold value, the WTRU may be triggered to determine or report a new desired set of dual modulation transmission parameters.

[0288] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on a change in a measured performance metric (e.g., change greater than threshold). For example, if a CCA correlation changes by more than a threshold value compared to a previously determined CCA correlation, the WTRU may be triggered to determine or report a new desired set of dual modulation transmission parameters.

[0289] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on a request from gNB. For example, the WTRU may be requested to transmit a desired set of dual modulation transmission parameters upon reception of an aperiodic request from the gNB.

[0290] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on a reception of DMRS or transmission using DMRS.

[0291] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on a priority of a transmission. For example, the WTRU may be triggered to determine or report a desired set of dual modulation transmission parameters upon reception of a transmission of a specific priority

[0292] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on a feedback resource payload. For example, the WTRU may be triggered to report a desired set of dual modulation transmission parameters when the feedback resource payload is greater than a threshold value; where the threshold value may be configurable and may depend on the size of dual modulation transmission parameters to be reported.

[0293] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on a TCI state or TCI state change.

[0294] The WTRU may be triggered to determine or report a set of dual modulation transmission parameters based on a transmission type. For example, a WTRU may report a desired set of dual modulation transmission parameters upon completing RA procedure.

[0295] A WTRU may determine and report a desired set of dual modulation transmission parameters.

[0296] The WTRU may report the desired set using UCI transmission in PUCCH or PUSCH. For example, the WTRU may be configured with periodic, aperiodic, or semi-persistent resources to report a desired set of dual modulation transmission parameters. Note that for aperiodic transmission, the WTRU may be triggered by the gNB or may be triggered autonomously. For WTRU-triggered aperiodic transmission, the WTRU may be configured with configured reporting resources (e.g., conditional reporting resources). In another method, for WTRU-triggered aperiodic transmission, the WTRU may request reporting resources when triggered to report the desired set. For example, the WTRU may multiplex the desired set of dual modulation transmission parameters with one or more of CSI, SR or HARQ-ACK.

[0297] The WTRU may report the desired set using HARQ-ACK feedback. For example, the WTRU may report enhanced HARQ-ACK feedback. The enhanced HARQ-ACK feedback may provide per-region feedback. The enhanced HARQ-ACK feedback may indicate whether the coding rate should be changed for one or more regions. The enhanced HARQ-ACK feedback may indicate whether to increase or decrease the coding rate for one or more regions. The enhanced HARQ-ACK feedback may indicate one or more new regions or boundaries.

[0298] The WTRU may report the desired set using MAC CE

[0299] The WTRU may report the desired set using RRC.

[0300] A WTRU may receive an indication of a set of dual modulation transmission parameters used in a DL transmission or to be used for an UL transmission

[0301] The WTRU may receive the indication of the set of dual modulation transmission parameters from a DCI. For example, a DCI may be enhanced to include new information elements indicating a set of dual modulation transmission parameters or an index thereof. The DCI may include new TBS mapping rules. A WTRU may be configured with one or more TBS mapping rules, for example each associated with a different set of dual modulation transmission parameters. The WTRU may determine the TBS value for one or more region as a function of the received one or more TBS indices in a DCI and the set of dual modulation transmission parameters. In another method, the WTRU may determine the TBS value for one or more regions as a function of the received one or more TBS indices and one or more offsets associated to one or more regions. The offset(s) may be included in the DCI.

[0302] The WTRU may receive the indication of the set of dual modulation transmission parameters from a region-specific DCI. For example, WTRU may receive a plurality of DCI scheduling transmissions in respective regions of a transmission.

[0303] The WTRU may receive the indication of the set of dual modulation transmission parameters from a CCA configuration. For example, a WTRU may determine a set of dual modulation transmission parameters from a CCA configuration

[0304] The WTRU may receive the indication of the set of dual modulation transmission parameters from a RRC (re)configuration.

[0305] The WTRU may receive the indication of the set of dual modulation transmission parameters from a MAC CE transmission.

[0306] The WTRU may receive the indication of the set of dual modulation transmission parameters implicitly. For example, a parameter of a DCI may be reused to indicate a set of dual modulation transmission parameters

[0307] The WTRU may receive the indication of the set of dual modulation transmission parameters based on a set used for another, possibly associated, transmission.

[0308] In an embodiment, the WTRU may be configured to determine the size of transport block for the physical channels associated with space CCA transmission based on preconfigured rules. In an embodiment, the WTRU may receive a space CCA transmission with dual modulation (e.g., a first modulation and a second modulation). In one embodiment, the WTRU may receive two MCS indices associated with a single PDSCH transmission. For example, the first MCS index may be associated with REs in the first region (e.g., Space CCA region and optionally its neighborhood) and the second MCS index may be associated with REs in the second region. For example, the WTRU may be preconfigured with two MCS tables - where the first table maps the first MCS index to the first code rate and a second table what maps the second MCS index to the second code rate. The WTRU may calculate the transport block size as a function of one or more of the following: the first code rate, second code rate, size of the first region, size of the second region, number of layers associated with space region etc

[0309] A WTRU may be configured with one or more space CCA configuration with dual modulation transmission mode.

[0310] The CCA configuration may include layer specific space CCA region configuration. The layer specific space CCA region may also be predefined (i.e., func(number of layers)).The layer specific space CCA region may be configured using one or more options: (1) mapping between (one or more) view formats(s) and layer(s); (2) geometry / boundaries - per layer config for - starting RE, size of the region and density; and / or modulation order (e.g., PCQI) used for the space CCA region REs.

[0311] The CCA configuration may include boundary associated with dual modulation transmission, where the boundary distinguishes the first set of REs modulated with the first modulation order (i.e., a first region) from the second set of REs modulated with the second modulation order (i.e., a second region)- configured using one or more of the following: (1) space CCA region boundary Flag (if the boundary is the same as the space CCA region boundary) and / or (2) boundary information (e.g., starting RE, size of the region).

[0312] The CCA configuration may include phase symbols format (locations, modulation order, etc.)

[0313] The CCA configuration may include performance metric associated with the dominant layer (e.g., one or more CCA correlation threshold(s))

[0314] A WTRU may receive a PDSCH associated with (e.g., initial) space CCA configuration with dual modulation transmission (e.g., a field in DCI).

[0315] The space CCA PDSCH with dual modulation transmission may include, for each layer, a set of symbols containing five groups of REs: a first group of REs carrying data associated with a first layer; a second group of REs carrying data from both a first layer and second layer, where the transmit power difference between the first layer and second layer is greater than a threshold and the number of REs in the second group relative to the sum of REs in the first and second groups is less than or equal to the configured overlap o%; a third group of REs carrying a CCA phase correction reference symbol; a fourth group of REs carrying data from both a first layer and second layer - where the transmit power for first layer may be equal to the second layer; and / or a fifth group of REs carrying data from both a first layer and second layer - possibly with equal power allocation across the first layer and second layer, and the fifth group of REs is adjacent to the first three groups of REs (e.g., spans one or more of the adjacent OFDM symbol(s) and / or subcarriers)

[0316] For example, the first three groups of REs may correspond to ‘space CCA region' per layer.

[0317] For example, the number of REs in the second group relative to the sum of REs in the first and second groups is less than or equal to the configured overlap a%. For example, the first three groups along with the fifth group of REs correspond to a first region and may be modulated with a first modulation order. For example, the fourth group of REs correspond to a second region and may be modulated with a second modulation order, where in the second modulation order may be lower than the first modulation order. For example, Space CCA regions for different layers are non-overlapping. For example, a field in DCI to indicate the new PDSCH format with space CCA transmission.

[0318] A WTRU may determines one or more parameters in support of the dual modulation transmission associated with the first and second region. For example, a WTRU may determines the precoded channel quality indicator (PCQI) for the one or more configured space CCA region(s). The WTRU may determine the PCQI based on the dominant layer detection performance in the assigned space CCA region (e.g., if measured CCA correlation exceeds a certain configured threshold, increment PCQI, otherwise use the same CQI or decrement CQI). In another embodiment, the WTRU may select the PCQI index based on the measured correlation and predefined mapping between correlation and modulation order.

[0319] A single PDSCH transport block with a combination of modulation scheme, target code rate and transport block size corresponding to the PCQI index, and occupying a group of downlink physical resource blocks associated with Space CCA transmission, could be received with a transport block error probability not exceeding- a threshold,

[0320] A WTRU may determine the boundary information between the different modulation regions (first region and second region), e.g., a binary flag indicating if the modulation boundary is aligned with the space CCA region boundary, starting RE of the new region if not aligned, the PCQI associated with the new region (e g., + / - 6PCQ I), based on one or more of the following conditions: (1) measured space CCA correlation in the first region should be exceeding a certain threshold; (2) measured change in the estimated channel (e.g., using CSI-RS) in the first region may be below a configured threshold; and / or (3) measured change in the combiner / equalizer domain in the first region may be below a configured threshold.

[0321] Upon meeting the trigger conditions (e.g., change in PCQI or boundary between regions, correlation threshold, time event (predefined periodicity)) for reporting dual modulation transmission mode parameters, the WTRU transmits the feedback on the preconfigured / allocated UL resources.

[0322] For example, a WTRU may transmit the PCQI index based on the measured correlation or the amount of change in the precoded channel, or the BLER associated with the higher order modulation region.

[0323] For example, a WTRU may transmit the boundary information between the first and second set of resources (i.e , first region and second region). Optionally, a binary flag indicating if the modulation boundary between the first and second region is aligned with the space CCA region boundary (i.e., the fifth group of REs is empty).

[0324] A WTRU may be configured with the updated dual modulation transmission parameters ((e g., where the configuration aspects may include one or more of parameters in step 1 (e.g., PCQI, updated boundary information).

[0325] A WTRU may receive PDSCH with updated space CCA under dual modulation transmission mode (e g., DCI with DL grant carries an indication of the PDSCH with new CCA format or dual modulation transmission model thereof)

[0326] A WTRU may process the received space CCA PDSCH with dual modulation transmission.

[0327] One or more channel estimation schemes for demodulation or CSI measurement may be used, where the channel estimation schemes may include at least one of DMRS, time-domain CCA, frequencydomain CCA, and spatial-domain / space CCA, and combinations of one or more of channel estimation schemes A mode of operation for a data channel (e.g , PDSCH or PUSCH) may be defined or determined based on associated channel estimation scheme.

[0328] A channel estimation scheme herein may be referred to as a reference resource transmission and / or reception method. For example, DMRS-based channel estimation scheme may be a channel estimation scheme based on transmitted / received DMRS; time-domain CCA based channel estimation scheme may be a channel estimation scheme based on repeated data symbols in time domain; frequency-domain CAA based channel estimation scheme may be a channel estimation scheme based on repeated data symbols in frequency domain; regular CCA based channel estimation may be referred to as a channel estimation scheme based on repeated data symbols in time and / or frequency; spatial (or space) domain CCA based channel estimation scheme may be a channel estimation scheme based on repeated data symbols in spatial domain.

[0329] A mode of operation may be defined or used, where a mode of operation may be determined based on associated channel estimation scheme. For example, a mode associated with DMRS based channel estimation may be referred to as legacy mode; a mode associated with regular CCA based channel estimation may be referred to as regular CCA mode; a mode associated with space CCA based channel estimation may be referred to as space CCA mode; and a mode associated with one or more modes (or channel estimation schemes) may be referred to as hybrid mode, where the hybrid mode may be associated with a combination of DMRS, regular CCA, and space CCA.

[0330] If a mode is associated with a PDSCH transmission / reception, it may be referred to as PDSCH mode; if a mode is associated with a PUSCH transmission / reception, it may be referred to as PUSCH mode; if a mode is associated with CSI, it may be referred to as CSI mode.

[0331] In an embodiment, a PDSCH RE mapping may be determine based on a PDSCH mode determined. For example, if a first PDSCH mode (e.g., legacy mode) is used, configured, or determined, a set of PDSCH REs may be mapped sequentially either time first or frequency first in the allocated PDSCH resources excluding some type of RS (e.g., DMRS, periodic CSI-RS); if a second PDSCH mode (e.g., regular CCA mode) is used, configured, or determined, a set of PDSCH REs may be mapped sequentially either time first or frequency first in the allocated PDSCH resources excluding some type of RS as well as resources reserved for CCA mode transmission.

[0332] In an embodiment, a WTRU may be configured with one or more PDSCH modes for a PDSCH transmission. For example, a first PDSCH mode may be configured, determined, or used for a first type of PDSCH data symbols and a second PDSCH mode may be configured, determined, or used for a second type of PDSCH data symbols.

[0333] The first and second type of PDSCH data symbols may be determined based on a layer number. For example, the data symbols associated with a first layer of the PDSCH may be configured, determined, or identified as a first type of PDSCH data symbols and the data symbols associated with a second layer of the PDSCH may be configured, determined, or identified as a second type of PDSCH data symbols.

[0334] The first and second type of PDSCH data symbols may be determined based on a symbol location. For example, the data symbols located in OFDM symbols close to DMRS may be configured, determined, or identified as a first type of PDSCH data symbols (e.g., legacy PDSCH mode) and the rest of the data symbols may be configured, determined, or identified as a second type of PDSCH data symbols.

[0335] The first and second type of PDSCH data symbols may be determined based on a priority. For example, when different priority traffics are multiplexed for a PDSCH transmission and / or reception, the data symbols associated with a first traffic type (or priority) may be configured, determined, or identified as a first type of PDSCH data symbol (e.g , use DMRS based channel estimation) and the data symbols associated with a second traffic type (or priority) may be configured, determined, or identified as a second type of PDSCH data symbol (e.g., use CCA-based channel estimation)

[0336] The first and second type of PDSCH data symbols may be determined based on a channel type; when a different type of channel is multiplexed in a PDSCH transmission, the data symbols associated with a first channel in a PDSCH (e g., control information) may be configured, determined, or identified as a first type of PDSCH data symbol and the data symbols associated with a second channel in the PDSCH (e.g., data information) may be configured, determined, or identified as a second type of PDSCH data symbol

[0337] The first and second type of PDSCH data symbols may be determined based on a target purpose. If one or more PDSCH data symbols are used for data transmission only, the one or more PDSCH data symbols may be configured, determined, or identified as a first type of PDSCH data symbol (e.g., use DMRS based channel estimation); if one or more PDSCH data symbols are used for data transmission and measurement (e g., phase noise, CSI measurement, time / frequency tracking), the one or more PDSCH data symbols may be configured, determined, or identified as a second type of PDSCH data symbol (e.g., use CCA based channel estimation), where the second type of PDSCH data symbols may be repeated in time / frequency / space

[0338] The first and second type of PDSCH data symbols may be determined based on a frequency band (or RB location).

[0339] The first and second type of PDSCH data symbols may be determined based on a time location (e g., OFDM symbols).

[0340] Herein, PDSCH mode may be used as an example to describe the proposed embodiments. However, the proposed embodiments may apply to other data transmission (e.g., PUSCH, PSSCH, PDCCH, PSCCH) and / or signal transmission (e.g., CSI-RS, TRS, PRS, SRS, DRS) without any restriction. Hereafter, PDSCH may be interchangeably used with PUSCH, PSSCH, PDCCH, and PSCCH but still consistent with the embodiments disclosed.

[0341] In an embodiment, a WTRU may report assistance information to determine a mode of operation (e g., PDSCH mode) The assistance information may include a preferred mode of operation mode for a set of REs (full or subset) in data transmission (e.g., PDSCH, PUSCH, PSSCH).

[0342] The assistance information may include One or more conditions which may be used to determine a mode of operation. A WTRU speed related information (e.g., Doppler frequency, WTRU speed, time-domain correlation) may be reported; a gNB may determine time-domain CCA if a WTRU speed is higher than a threshold, otherwise, the gNB may determine frequency-domain CCA. A spatial correlation related information (e g., antenna correlation, channel covariance matrix, etc.). When spatial correlation is lower than a threshold, space CCA mode may be used or determined; otherwise, regular CCA mode may be used.

[0343] The assistance information may include channel estimation performance related information. For a given mode of operation, a WTRU may report channel estimation performance related information (e.g., MSE) in periodic, semi-persistent, or aperiodic manner, where the semi-persistent or aperiodic case, the reporting may be triggered when one or more predetermined conditions are met (e.g., channel estimation performance is below a threshold)

[0344] In an embodiment, a WTRU may be indicated a PDSCH mode for a PDSCH transmission. One or more of following may apply:

[0345] A bit field (or a codepoint) in the scheduling DCI for a PDSCH transmission may be used to indicate a PDSCH mode for the PDSCH transmission.

[0346] A PDSCH mode may be determined based on associated scheduling DCI format. For example, when DCI format 1-1 is used, a first PDSCH mode may be used; otherwise, a second PDSCH mode may be used. Alternatively, a first PDSCH mode may be used when a fallback DCI is used (e.g., DCI format 1-0) and a second PDSCH mode may be used when non-fallback DCI is used, where the first PDSCH mode may be predetermined (e.g., legacy mode) and the second PDSCH mode may be configured (e.g., legacy mode, regular CCA mode, and space CCA mode).

[0347] A PDSCH mode may be determined based on RNTI scrambled on the CRC for the scheduling DCI. For example, a first RNTI may be associated with a first PDSCH mode and a second RNTI may be associated with a second PDSCH mode.

[0348] Dynamic PDSCH mode indication (or adaptation) is only allowed when PDSCH scheduling offset (Kmin) is larger than a threshold (e.g., Kmin>1). For example, dynamic PDSCH mode indication / adaptation is not allowed for the same slot scheduling case (i.e., PDCCH and PDSCH are in the slot) to avoid WTRU processing time becomes larger.

[0349] The required WTRU minimum processing time may be determined whether dynamic PDSCH mode or semi-static PDSCH mode is used. For example, if a PDSCH mode is configured, or determined via a higher layer signaling (e.g., RRC, MAC-CE), a first WTRU minimum processing time may be applied; if a PDSCH mode is dynamically indicated, or determined via a DCI signaling, a second WTRU minimum processing timemay be applied; where, the first WTRU minimum processing time may be shorter than the second WTRU minimum processing time.

[0350] In another embodiment, a WTRU may be indicated with one or more PDSCH modes for a PDSCH transmission. For example, a first subset of PDSCH REs may be configured or determined to be associated with a first PDSCH mode (e.g , legacy mode) and a second subset of PDSCH REs may be indicated dynamically (e.g., in DCI) which PDSCH mode to use for demodulation (e.g., legacy mode, regular CCA mode, space CCA mode), where the actual transport block size may be determined based on PDSCH mode determined A PDSCH mode may be indicated in a DCI associated with the PDSCH transmission (e.g., for dynamic grant). A PDSCH mode may be indicated in a common DCI which may be shared by one or more WTRUs.

[0351] In an embodiment, a WTRU may determine a PUSCH mode based on one or more conditions, where a WTRU may be configured with a set of PUSCH modes within which the WTRU may determine a PUSCH mode for a PUSCH transmission.

[0352] One or more of following conditions may be used to determine a PUSCH: WTRU speed; transmission power determined or used; waveform determined or used; scheduling parameters (e.g., rank, MCS, DMRS pattern, number of symbols, etc.); multiplexing condition (e.g., UCI, PTRS, SRS, etc.); slot type (e g., UL only slot, flexible slot, special slot, SBFD slot); traffic type (e.g., eMBB, URLLC, mMTC); and channel condition (e.g., SINR)

[0353] For a configured grant, a WTRU may be configured with a set of PUSCH modes in the configuration of the configured grant. The WTRU may determine a PUSCH mode.

[0354] A WTRU may indicate a determined PUSCH mode based on one or more of following: a UCI which may indicate the determined PUSCH mode may be multiplexed in the PUSCH (e.g., a first symbol of the PUSCH); one or more DMRS sequences may be defined or configured and each DMRS sequence may be associated with a PUSCH mode (the WTRU may determine a DMRS sequence based on the PUSCH mode determined); one or more PUSCH resources (e.g., PUSCH resources are separate in time / frequency) may be configured, determined, or used, where each PUSCH resource may be associated with a PUSCH mode. The WTRU may transmit a PUSCH in the determined PUSCH resource associated with the determined PUSCH mode.

[0355] A WTRU supporting several modes of operation (e.g., PDSCH modes such as regular CCA, Space CCA, DMRS mode) may be configured to operate using a first mode of operation. The WTRU may be triggered to determine and / or report the assistance information for parameters of the first mode of operation, or for determining a second mode of operation, where the triggers may be event-based, time-based, or NW-based.

[0356] Event-based triggers may include a change in channel conditions, e.g., Doppler or delay spread. In one embodiment, the WTRU may measure the channel conditions (e.g. based on the received CSI-RS). When the difference (or relative change) between the current and the previous (e.g., used for the previous mode ofoperation reporting) channel conditions exceed a configured threshold for a number (e.g. consecutive) of measurement periods (e.g., slots, TTIs), the WTRU may be triggered to determine a second mode of operation or updated parameters for the first mode of operation (e.g., PDSCH mode). The WTRU may make this determination as a function of the change in the channel conditions and the current mode of operation and parameters

[0357] For example, if the measured Doppler is high (in case of time selective channels) and the first (e.g. current) mode of operation is Space CCA, the WTRU may determine a second mode of operation as Time CCA; if the first mode of operation is Time CCA, the WTRU may (e.g. may only) determine the updated parametersfor the Time CCA mode of operation, or the WTRU may determine the PDSCH mode as the second mode of operation. In another example, if the measured Doppler is low and the first mode of operation is Time CCA, the WTRU may determine the second mode of operation e g. as Space CCA, or hybrid (Space CCA for a layer or set of layers, and regular CCA for other layers).

[0358] For example, if the measured delay spread is high (as in the case of frequency selective channels) and the first (e.g. current) mode of operation is Space CCA, the WTRU may determine the second mode of operation as Frequency CCA; in another example, if the first mode of operation is Frequency CCA, the WTRU may determine (e.g. only determine) updated parameters for the Frequency CCA, or may determine the second mode of operation as hybrid mode (e.g. Frequency CCA for a layer / set of layers, and Space CCA for other layers)

[0359] Event-based triggers may include a Change in the rank (e.g., Rl) determined by the WTRU For example, when based on CSI-RS measurements the WTRU determines that the rank has changed (with respect to the previous TTI or the previous configuration of the mode of operation), the WTRU may be triggered to determine a new (e.g., second) mode of operation (e.g., PDSCH mode). The WTRU may determine the second mode of operation based on the measured rank, a configured rank threshold and the current (e.g., first) mode of operation For example, if the measured rank is lower than a configured threshold, the WTRU may determine Space CCA as a second mode of operation.

[0360] Event-based triggers may include a change in the layer indicator (e.g., LI or index of the strongest layer) determined by the WTRU For example, when based on channel measurements (e.g, based on CSI- RS), the WTRU finds that the index of the strongest layer has changed, the WTRU may be triggered to determine a new (e.g, second) mode of operation or to determine updated parameters For example, if the new strongest layer was configured for Regular CCA or DM RS mode of operation, the second mode of operation may be hybrid, where the strongest layer operates with Space CCA, and the other layers operate with Regular CCA.

[0361] Event-based triggers may include CCA correlation measurements. In one embodiment, the WTRU may be triggered to determine a second mode of operation and / or parameters for the first mode of operation, as a function of the first mode of operation, number of layers, and measurements of the CCA correlation(measured on the data channel). The use of CCA correlation measurements for determining the mode of operation may reduce the feedback latency (as the CCA correlation may be performed at TTI granularity, which may be lower than the granularity CSI-RS based channel measurements). In another embodiment, the WTRU may recommend space CCA if the CCA correlation difference between dominant layer and the sum of correlations of non-dominant exceeds a certain configured correlation threshold.

[0362] Event-based triggers may include performance measurements (e.g , SNR, RSRP, RSRQ, BLER, correlation between rx antennas). In one embodiment, the WTRU may be configured with SNR ranges and Rx antenna correlation ranges to determine the mode of operation. For example, when operating at low SNR and with high correlation between the Rx antennas, the WTRU may determine the DM RS mode as the second mode of operation (see the throughput in FIG. 16), while when operating at low SNR and with low Rx antenna correlation, the WTRU may determine Space CCA as the second mode of operation.

[0363] Event-based triggers may include the WTRU being triggered to report a second mode of operation or parameters for the first mode of operation if different from the previous report. The WTRU may skip reporting when no change of the mode of operation / parameters was found, with respect to the previous report.

[0364] Examples of time-based triggers may include a WTRU configuration for periodic, or aperiodic reporting of the mode of operation. For example, the WTRU may be configured to report the mode of operation (e g. the preferred mode of operation, or the preferred parameters for the current mode of operation) as part of the configured CSI report (periodic or semi-persistent). In another example, the WTRU may use the HARQ feedback to signal an indication (e.g., 1-bit) to the NW of a change in the preferred mode or operation or preferred parameters. In yet another example, the WTRU may be configured with periodic resources (e.g., dedicated data channel grants, new PUCCH formats) for reporting the mode of operation.

[0365] NW-based triggers may include at least one of the following: BWP change; beam failure detection; RLF detection; based on the reception of an RRC reconfiguration from the NW; handover to another cell; and / or TRP change;

[0366] When any of the above changes / events occur, the WTRU may be triggered to determine a second mode of operation and / or parameters for the mode of operation; the WTRU may be triggered to report the second mode of operation / parameters, e.g., when it determines that a change of the mode / parameters of operation occurred, as compared to the previous report.

[0367] A WTRU may be configured to report the mode of operation (e.g., PDSCH mode), and / or the parameters of the mode of operation.

[0368] The report may include assistance information for the determination of the mode (e.g., second mode) / parameters of operation. For example, the report may include measured channel conditions, such as: doppler spread, delay spread, AoA, channel rank, index of the strongest layer, SNR, RSRP, RSRQ, Channel correlation bandwidth, channel correlation time, and / or Correlation between Rx antennas (spatial correlation).

[0369] The report may include, CCA correlation measurements, such as CCA correlation per each layer, CCA correlation per sub-band, average CCA correlation. The report may include preferred (e.g., second) mode of operation, for example: Regular CCA, Space CCA, or DMRS mode. The report may include, view parameters (e g., for regular CCA modes). The report may include, space CCA view parameters, for example CCA region boundaries, number of REs in the CCA region.

[0370] The WTRU may report the mode of operation when it determines that a change occurred in the preferred mode of operation. The WTRU may use a first report (e.g., with a small payload size) to indicate the change, for example 1 -bit flag multiplexed with the HARQ feedback. The WTRU may use a second report to indicate the determined parameters, where the report may be multiplexed with the CSI report, for example with an aperiodic CSI report over PUSCH.

[0371] To demonstrate the effectiveness of the proposed PDSCH format and to show that dynamic switching or multiplexing different PDSCH formats may be beneficial, an end-to-end throughput performance of the different PDSCH modes is evaluated on a 3GPP testbench and shown in FIG. 16. The following simulation parameters are used; a transmitter with 16 antennas, a receiver with 4 antennas, CDL-C channel model, 4 GHz carrier frequency, 52 RBs bandwidth, 30 ns delay spread, 5 km / hr WTRU speed, single layer transmission. The CCA problem is solved once for every two RBs For regular CCA, time repetition is used where for each RB data is repeated from OFDM symbol 3 to OFDM symbol 10, for only the even subcarriers, thus making the number of reserved REs equal to 6 per RB. Similarly, the DM RS configuration uses six reference symbols per RB.

[0372] It can be seen that under the considered parameters, space CCA provides considerable throughput gains relative to the DMRS and regular CCA at different SNR regions. It can also be seen that regular CCA outperforms DMRS at most of the SNR regions while the latter is slightly better at the low SNR region. It is expected that the performance of space CCA may slightly degrade when the number of layers exceeds a certain threshold under different overlap and power difference setting This suggest that different PDSCH modes may have different performance under different settings, and hence, motivating the need for multiplexing different PDSCH modes or enabling dynamic switching between the different modes FIG. 10 is a graph illustrating end-to-end performance of different PDSCH modes.

[0373] Different CCA modes and DMRS have different performance trade-offs under different conditions. This solution describes methods and procedures for dynamic adaptation between multiple PDSCH formats / transmissions / modes (e g., DMRS, regular CCA, space CCA). The below describes an exemplary process to multiplex different formats (e.g., DMRS, space CCA, regular CCA) within one transmission for optimized performance

[0374] A WTRU may be configured with dynamic PDSCH transmission, where the transmission includes one or more multiplexed PDSCH mode(s) (e.g., DMRS, space CCA, regular CCA). The configuration may include PDSCH modes (& parameters thereof), including legacy mode: DMRS, regular CCA mode, space CCAmode, and hybrid modes (e.g. , layer specific or sub-band specific configuration) The hybrid mode may include DMRS + Regular CCA, DMRS + Space CCA, Regular + Space CCA, and DMRS + Space + Regular CCA.

[0375] The configuration may include feedback configuration, including conditions / parameters to enable dynamic adaptation (e.g., space CCA feedback irrespective of PDSCH mode).

[0376] The WTRU may receive PDSCH with a first mode (e.g., DMRS, Regular, Space CCA or Hybrid).

[0377] The WTRU may determine preferred PDSCH mode (per layer and / or per sub band) based on measurements based on WTRU measurements (e.g., channel measurements (Doppler, SNR, CQI), interference measurements, Rl). For example, the WTRU may recommend space CCA based on Rl or configured number of layers, e.g., if Rl is below a certain configured threshold. In another solution, WTRU may recommend space CCA if the CCA correlation difference between dominant layer and the sum of correlations of non-dominant exceeds a certain configured correlation threshold. The WTRU may recommend DMRS under certain channel conditions, e.g., high Doppler scenarios, e.g., if estimated Doppler exceeds a certain threshold.

[0378] The WTRU may indicate the layer specific preferred PDSCH mode of operation and the associated parameters (e.g., in a UCI or MAC CE).

[0379] The WTRU may determine layer specific PDSCH mode of operation (e.g., DMRS vs space CCA vs regular CCA), implicitly based on other information, such as MCS indication, rank, waveform, retransmission etc.) The WTRU may be preconfigured with rules for DMRS vs CCA type transmissions based on waveform. For example, if the waveform is OFDM, the WTRU may assume all PDSCH modes are applicable, else if the waveform is DFT-s-OFDM, the WTRU may assume DMRS. The WTRU may be configured with mapping between retransmission index and PDSCH mode (e g., initial transmission with Space or regular CCA and retransmission with DMRS. The WTRU may determine layer specific PDSCH mode of operation (e.g., DMRS vs space CCA vs regular CCA), based on an explicit indication in DCI ((e.g., bitmap to indicate PDSCH mode(s))

[0380] The WTRU may process the received PDSCH corresponding to the one or more modes.

[0381] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magnetooptical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a UE, WTRU, terminal, base station, RNC, or any host computer.

Claims

CLAIMSWhat is Claimed:

1. A method performed by a wireless transmit / receive unit (WTRU) comprising: receiving a physical downlink shared channel (PDSCH) associated with a space canonical correlation analysis (CCA) transmission, wherein the space CCA transmission includes a group of resource elements (REs), including: a first group of REs for carrying data associated with a first layer; a second group of REs for carrying data from the first layer and a second layer, wherein a transmit power difference between the first layer and the second layer is greater than a threshold; a third group of REs for carrying a CCA phase correction reference symbol; and a fourth group of REs for carrying data from the first layer and data from the second layer, wherein the transmit power of the first layer is equal to the transmit power of the second layer; constructing a first space CCA view and a second space CCA view in a receive antenna domain in a space CCA region; and decoding the first group of REs, the second group of REs, and the fourth group of REs in the space CCA transmission.

2. The method of claim 1 , further comprising: receiving configuration information associated with a space CCA transmission.

3. The method of claim 2, wherein the configuration information includes a PDSCH format.

4. The method of claim 2, wherein the configuration information includes a layer specific space CCA region configuration5. The method of claim 2, wherein the configuration information includes a percentage of overlap between the first layer and the second layer.

6. The method of claim 1 , further comprising: utilizing the third group of REs for a phase correction.

7. The method of claim 1 , wherein the space CCA regions includes the first group of REs, the second group of REs, and the third group of REs8. The method of claim 1 , wherein the first space CCA view is constructed from a first set of receive antenna elements and the second space CCA view is constructed from a second set of receive antenna elements.

9. The method of claim 8, wherein the first set of receive antenna elements does not overlap with second set of receive antenna elements.

10. A wireless transmit / receive unit (WTRU) comprising: a transceiver; and a processor; wherein the transceiver and processor are configured to: receive a physical downlink shared channel (PDSCH) associated with a space canonical correlation analysis (CCA) transmission, wherein the space CCA transmission includes a group of resource elements (REs), including: a first group of REs for carrying data associated with a first layer; a second group of REs for carrying data from the first layer and a second layer, wherein a transmit power difference between the first layer and the second layer is greater than a threshold; a third group of REs for carrying a CCA phase correction reference symbol; and a fourth group of REs for carrying data from the first layer and data from the second layer, wherein the transmit power of the first layer is equal to the transmit power of the second layer; construct a first space CCA view and a second space CCA view in a receive antenna domain in a space CCA region; and decode the first group of REs, the second group of REs, and the fourth group of REs in the space CCA transmission.

11. The WTRU of claim 10, further comprising: receiving configuration information associated with a space CCA transmission.

12. The WTRU of claim 11 , wherein the configuration information includes a PDSCH format.

13. The WTRU of claim 11, wherein the configuration information includes a layer specific space CCA region configuration14. The WTRU of claim 11, wherein the configuration information includes a percentage of overlap between the first layer and the second layer.

15. The WTRU of claim 10, further comprising: utilizing the third group of REs for a phase correction.

16. The WTRU of claim 10, wherein the space CCA regions includes the first group of REs, the second group of REs, and the third group of REs17. The WTRU of claim 10, wherein the first space CCA view is constructed from a first set of receive antenna elements and the second space CCA view is constructed from a second set of receive antenna elements.

18. The WTRU of claim 17, wherein the first set of receive antenna elements does not overlap with second set of receive antenna elements.

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