DMRS enhancements

Abstract

A WTRU may receive a DCI that includes information that schedules a transmission and associates a DMRS port with a CDM group. Based on the DCI, the WTRU may associate a first DMRS port with a first CDM group, and associate a second DMRS port with a second CDM group. The WTRU may map the first DMRS port associated with the first CDM group to a first antenna group, and may map the second DMRS port associated with the second CDM group to a second antenna group. The WTRU may transmit at least a first DMRS using the first DMRS port and the first antenna group, and may transmit at least a second DMRS using the second DMRS port and the second antenna group. The WTRU may select the first DMRS port based on the MCS, associate a first PTRS port with the first DMRS port, and transmit the PTRS using the PTRS port.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Provisional U.S. Patent Application No. 63 / 335,504 filed on April 27, 2022, Provisional U.S. Patent Application No. 63 / 395,457 filed on August 5, 2022, Provisional U.S. Patent Application No. 63 / 411,355 filed on September 29, 2022, Provisional U.S. Patent Application No. 63 / 422,069 filed on November 3, 2022, and Provisional U.S. Patent Application No. 63 / 445,342 filed on February 14, 2023, the disclosures of all of which are incorporated herein by reference in their entirety. Background Art

[0003] Mobile communications using wireless communications continue to evolve. The fifth generation may be referred to as 5G. Previous (legacy) mobile communications may be, for example, fourth generation (4G) Long Term Evolution (LTE). Summary of the invention

[0004] Systems, methods, and tools for DMRS enhancement are described herein.

[0005] A wireless transmit and receive unit (WTRU) may be configured to map code division multiplexing (CDM) groups to demodulation reference signal (DMRS) ports. The WTRU may transmit information associated with at least one of a coherence capability or an antenna layout of the WTRU to a base station. The information may include, for example, information identifying one or more coherent antenna groups. The information may indicate the number of coherent antenna groups included in the WTRU, such as one, two, etc.

[0006] A base station, which may be, for example, a gNodeB, may receive information associated with at least one coherence capability or antenna layout of the WTRU. The base station may determine information for scheduling transmissions and associating DMRS ports with CDM groups based on the information associated with the at least one coherence capability or antenna layout. The base station may transmit information for scheduling transmissions (which may be, for example, a PUSCH transmission) and associating DMRS ports with CDM groups to the WTRU. The information may be formatted as downlink control information (DCI).

[0007] The WTRU may receive DCI from a base station. The DCI may include information scheduling transmissions and associating DMRS ports with CDM groups. The received information scheduling transmissions and associating DMRS ports with CDM groups may be based on previously transmitted information identifying one or more coherent antenna groups.

[0008] The WTRU may determine a first one or more DMRS ports and a second one or more DMRS ports. The WTRU may associate the first one or more DMRS ports with a first CDM group and associate the second one or more DMRS ports with a second CDM group based on the DCI. The WTRU may map the first one or more DMRS ports associated with the first CDM group to a first antenna group and may map the second one or more DMRS ports associated with the second CDM group to a second antenna group.

[0009] The WTRU may transmit a scheduled transmission including, for example, at least a first DMRS transmitted using the first one or more DMRS ports and the first antenna group and at least a second DMRS transmitted using the second one or more DMRS ports and the second antenna group.

[0010] The WTRU may be configured to associate a phase tracking radio signal (PTRS) port with a DMRS port. The DCI received at the WTRU may specify a first PTRS port. The WTRU may determine the first DMRS port from the first one or more DMRS ports or the second one or more DMRS ports based on a modulation and coding scheme (MCS) value. The WTRU may determine the first DMRS port based on an MCS value associated with the first DMRS port as the highest MCS value associated with either the first one or more DMRS ports or the second one or more DMRS ports. The WTRU may select the first DMRS port based on, for example, an MCS associated with the first DMRS port indicating that the first DMRS port is associated with a strong link (e.g., the strongest link) for uplink transmissions. The WTRU may associate the first PTRS port with the first DMRS port mapped to the first antenna group. The transmission transmitted by the WTRU may include a PTRS transmitted using the PTRS port.

[0011] The DCI received at the WTRU may specify a plurality of ports, including, for example, a first PTRS port and a second PTRS port. The WTRU may associate the first PTRS port with a first DMRS port mapped to a first antenna group, and may associate the second PTRS port with a second DMRS port mapped to a second antenna group. A transmission transmitted by the WTRU may include a first PTRS transmitted using the first PTRS port and a second PTRS transmitted using the second PTRS port. The transmission may also include a physical uplink shared channel (PUSCH) transmission.

[0012] The DMRS enhancement may include improved cross-panel DMRS interference management. The WTRU may be configured to determine a first antenna panel and a second antenna panel. The WTRU may receive a DCI including a plurality of fields associated with an antenna panel and may determine the first antenna panel and the second antenna panel based on the DCI. The DCI may also include an indication to transmit simultaneously using the first antenna panel and the second antenna panel. The WTRU may transmit to a first TRP using the first antenna panel and the first resource and may transmit to a second TRP simultaneously using the second antenna panel and the first resource.

[0013] The WTRU may be configured to determine that a first antenna panel is orthogonal to a second antenna panel. The WTRU may determine that the first antenna panel is orthogonal to the second antenna panel based on a timing advance. The WTRU may determine to transmit simultaneously according to the first antenna panel and the second antenna panel based on the first antenna panel being orthogonal to the second antenna panel. The WTRU may determine that a third antenna panel is not orthogonal to the first antenna panel. The WTRU may determine to rate match around a PUSCH resource of the third antenna panel.

[0014] The WTRU may be configured to determine a plurality of DMRS ports. The WTRU may determine a first group of DMRS ports and a second group of DMRS ports among the plurality of DMRS ports. The WTRU may associate the first group of DMRS ports with a first scheduling time slot and associate the second group of DMRS ports with a second scheduling time slot.

[0015] The WTRU may receive an indication that the DMRS resource element location is subject to change across PUSCH transmission instances. The WTRU may receive a DCI and may determine a DMRS port for transmission based on the DCI. The WTRU may determine a DMRS port for transmission based on at least an uplink antenna port code in the DCI.

[0016] The DMRS enhancement may include enhanced OCC mapping. The WTRU may be configured to determine a first group of OCCs spanning a first set of resource elements, and to determine a second group of OCCs spanning a second set of resource elements. The WTRU may determine that at least one resource element is included in the first set of resource elements and in the second set of resource elements. The WTRU may determine that for at least one resource element, a covering code coefficient associated with a first group of OCCs and a covering code coefficient associated with a second group of OCCs for a transmit port are the same. For the same transmit port, the covering code coefficients used by different OCC groups on shared resource elements may be the same. The transmit port may be a DMRS port.

[0017] The DMRS enhancement may include increasing the number of DMRS ports. Increasing the number of DMRS ports may, for example, involve a new DMRS mapping mode for SU / MU MIMO. The WTRU may be configured to receive information indicating a configuration for the DMRS. The WTRU may determine a mode for DMRS transmission based on the configuration for the DMRS. The WTRU may determine the number of resource elements for an OFDM symbol based on the mode for DMRS transmission. The WTRU may then determine to apply an OCC length to the DMRS transmission based on the configuration for the DMRS, and may transmit the DMRS transmission using the mode for DMRS transmission. If the mode for DMRS transmission is the first mode or the second mode, the WTRU may reduce the number of resource elements for the OFDM symbol to two resource elements, and may apply an OCC length of 2 or 4 to the DMRS transmission, depending on the DMRS configuration. If the mode for DMRS transmission is the third mode or the fourth mode, the WTRU may reduce the number of resource elements for the OFDM symbol to one resource element, and may apply an OCC length of 4 or 8 to the DMRS transmission, depending on the DMRS configuration.

[0018] The WTRU may be configured to provide enhanced CDM grouping. The WTRU may determine a first plurality of DMRS ports and associate the first plurality of DMRS ports with a first CDM group. The WTRU may determine a second plurality of DMRS ports and associate the second plurality of DMRS ports with a second CDM group. The WTRU may use the first plurality of DMRS ports and use the second plurality of DMRS ports to convey information. One or more DMRS ports of the first plurality of DMRS ports and one or more DMRS ports of the second plurality of DMRS ports may be associated with the first CDM group. Resources associated with the first CDM group may be mutually exclusive with resources associated with the second CDM group. The WTRU may be further configured to determine one or more PTRS ports and associate one or more PTRS ports with the first plurality of DMRS ports based on characteristics of the first plurality of DMRS ports.

[0019] The WTRU may be configured to provide enhanced DMRS mapping. The WTRU may be configured to determine an FD-OCC length associated with an FD-OCC. The WTRU may determine an FD-OCC length associated with one or more isolated resource elements. If the WTRU determines that the FD-OCC length is associated with one or more isolated resource elements, the WTRU may determine an offset FD-OCC to align with the scheduled transmission. The WTRU may determine an offset FD-OCC to align with the scheduled transmission based on a dynamic indication of an offset OCC mapping for the scheduled transmission. The dynamic indication may be received as part of the scheduling DCI. The WTRU may determine an offset FD-OCC to align with the scheduled transmission based on an index of a reference PRB for the scheduled transmission. The WTRU may determine an offset FD-OCC to align with the scheduled transmission based on an indicated set of antenna ports. A first group of antenna ports may be associated with a first OCC mapping, and a second group of antenna ports may be associated with a second OCC mapping.

[0020] The WTRU may be configured to provide an enhanced PTRS configuration. The WTRU may determine a plurality of antenna groups, wherein each antenna group in the plurality of antenna groups includes a plurality of antennas. The WTRU may determine one or more DMRS ports for each antenna group in the plurality of antenna groups, associate each antenna group in the plurality of antenna groups with a CDM group, and associate one or more PTRS ports with each DMRS port in the one or more DMRS ports. The WTRU may associate the one or more PTRS ports with each DMRS port in the one or more DMRS ports by determining the number of the plurality of antenna groups and determining the number of PTRS ports based on the number of the plurality of antenna groups. The WTRU may associate the one or more PTRS ports with each DMRS port in the one or more DMRS ports based at least in part on a DCI. The WTRU may associate the one or more PTRS ports with each DMRS port in the one or more DMRS ports based at least in part on a DCI and a MAC-CE. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented.

[0022] Figure 1B is an example of a method that can be used according to an embodiment of the present invention. Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within the illustrated communication system.

[0023] Figure 1C is an example of a method that can be used according to an embodiment of the present invention. Figure 1ASystem diagram of an example Radio Access Network (RAN) and an example Core Network (CN) for use within the illustrated communication system.

[0024] Figure 1D is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of yet another example RAN and yet another example CN for use within the illustrated communication system.

[0025] Figure 2A Example DMRS configuration types are depicted.

[0026] Figure 2B Example DMRS configuration types are depicted.

[0027] Figure 3 An example extension of DMRS ports over time slots is depicted.

[0028] Figure 4 An example OCC is depicted.

[0029] Figure 5 An example of overlapping OCCs is depicted.

[0030] Figure 6 An example of DMRS mapping with overlapping OCCs is depicted.

[0031] Figure 7 An example DMRS mapping for a CP-OFDM waveform is depicted.

[0032] Figure 8 An example DMRS mapping for a CP-OFDM waveform is depicted.

[0033] Fig. 9 An example DMRS mapping for a CP-OFDM waveform is depicted.

[0034] Fig.10 An example DMRS mapping for a CP-OFDM waveform is depicted.

[0035] Fig.11 An example DMRS mapping for a CP-OFDM waveform is depicted.

[0036] Fig.12 An example DMRS mapping for a CP-OFDM waveform is depicted.

[0037] Fig.13 An example DMRS mapping for a CP-OFDM waveform is depicted.

[0038] Fig.14 Example DMRS port indication and selection are depicted.

[0039] Fig.15An example MU-MIMO transmission is depicted.

[0040] Fig.16 An example table indicating a PTRS-DMRS single-port association is depicted.

[0041] Fig.17 An example table indicating a subset of configured PTRS-DMRS port associations is depicted.

[0042] Fig.18 Depicted is an example table indicating a subset of PTRS-DMRS port associations for a configuration of 2 ports.

[0043] Fig.19 An example table indicating predefined or preconfigured PTRS-DMRS port associations is depicted.

[0044] Fig. 20 An example table indicating re-interpreted PTRS-DMRS port associations is depicted.

[0045] Fig.21 Example implementations for antenna groups and PTRS-DMRS determination are depicted.

[0046] Fig. 22 Depicted is an example CDM / DMRS mapping to antenna groups for 8-layer transmission. DETAILED DESCRIPTION

[0047] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings.

[0048] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word discrete Fourier transform (DFT) spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0049] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0050] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is 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 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a next generation Node B (gNB), an NR Node B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0051] The base station 114a may be part of the RAN 104 / 113, 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), a relay node, etc. The base station 114a and / or the base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0052] 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).

[0053] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. 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 ​​UL Packet Access (HSUPA).

[0054] 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 Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0055] 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 New Radio (NR).

[0056] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using the dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0057] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0058] Figure 1AThe base station 114b in the may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0059] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Although not described in detail in the text, the CN 106 / 115 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0060] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0061] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0062] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0063] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0064] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from the base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, IR, UV or visible light signals. In another embodiment, the send / receive element 122 may be configured to send and / or receive both RF signals and optical signals. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0065] Although the transmit / receive element 122 Figure 1B Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0066] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0067] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0068] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0069] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0070] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 138 may include one or more sensors, which may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0071] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via signal processing performed via hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0072] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 according to one 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.

[0073] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0074] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0075] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0076] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. 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.

[0077] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0078] 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.

[0079] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include or may be in communication with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0080] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0081] In a representative embodiment, the other network 112 may be a WLAN.

[0082] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STA) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and leading to the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the target STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Direct link establishment (DLS) may be used to transmit point-to-point traffic between the source STA and the target STA (e.g., directly between them). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0083] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send a beacon on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be a working channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may listen to the primary channel. If the primary channel is listened / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0084] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0085] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For the 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be sent by sending STA. At the receiver of the receiving STA, the above-mentioned operations for the 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0086] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0087] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operation mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting (supporting only) a 1MHz operation mode) is sending to the AP, the entire available band may be considered busy even if most of the band remains idle and may be available.

[0088] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0089] Figure 1D1 is a system diagram illustrating the RAN 113 and the CN 115 according to one embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0090] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0091] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0092] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in the unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-B 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0093] 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 UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0094] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0095] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing in order to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 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.

[0096] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure the traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0097] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0098] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0099] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU102a-d, base station 114a-b, evolved Node B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b and / or any other device described herein. The simulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0100] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communications to perform testing.

[0101] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which may include one or more antennas) can be used by the simulation device to send and / or receive data.

[0102] The present application discloses DMRS enhancements. DMRS enhancements may involve, for example, increasing the number of ports, supporting simultaneous multi-panel transmissions, and / or supporting 8TX WTRUs. The disclosed DMRS enhancements may include procedures for cross-panel DMRS interference management. Cross-panel DMRS interference management may involve, for example, solutions for cross-panel DMRS pairing and orthogonal / non-orthogonal mapping. The disclosed DMRS enhancements may include procedures for enhanced OCC mapping. Enhanced OCC mapping may involve the use of shared / overlapping OCCs. The disclosed DMRS enhancements may include procedures for increasing the number of DMRS ports. Increasing the number of DMRS ports may, for example, involve new DMRS mapping modes for SU / MU MIMO. The disclosed enhancements may be applicable to and may be used for, for example, the transmission of signals (such as demodulation reference signals, broadcast reference signals, etc.) having specific transmission modes in the time domain, frequency domain, and code domain. For the sake of brevity of description, PUSCH DMRS or PDSCH DMRS may be discussed by way of example.

[0103] Demodulation reference signal (DMRS) configurations that define the placement of reference signals in time and frequency can be designed to address various scenarios with the goal of maintaining high design flexibility and forward compatibility while addressing implementation complexity and constraints from a receiver perspective. The placement pattern of pilots can be part of, e.g., an important part of, the design of an efficient multiple-input multiple-output (MIMO) communication system because the placement pattern can affect the number of orthogonal antenna ports supported for single-user (SU) / multi-user (MU) MIMO (SU / MU-MIMO) transmissions.

[0104] Figure 2A and Figure 2B Depicted are examples of DMRS configuration types for a cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform. Figure 2A The first example DMRS configuration type depicted in FIG. 1 may be referred to as DMRS configuration type 1. Figure 2B The second example DMRS configuration type depicted in FIG. 2 may be referred to as DMRS configuration type 2. The two example configurations may support single-symbol DMRS mapping and dual-symbol DMRS mapping. In order to efficiently use the available resources, orthogonal cover codes (OCCs) may be used to support multi-port operation of DMRS. For example, in the single-symbol configuration shown, two antenna ports using the same resource element may be orthogonalized by using a length 2-OCC, while for a dual-symbol configuration, four antenna ports may be orthogonalized by using a length 4-OCC.

[0105] The DMRS configuration type may specify the density of DMRS in the frequency domain and may determine the number of orthogonal antenna ports that may be supported per physical resource block, such as the maximum number. The difference between the configuration types may be that DMRS configuration type 1 may have a denser pilot frequency domain occupancy than DMRS configuration type 2, which may make DMRS configuration type 1 more resilient to frequency domain channel changes. On the other hand, DMRS configuration type 2 may have more orthogonal antenna ports (although the DMRS density may be reduced as a tradeoff). Therefore, DMRS configuration type 1 may support up to 4 orthogonal ports for a single symbol configuration and up to 8 orthogonal ports for a dual symbol configuration. DMRS configuration type 2 may support up to 6 orthogonal ports for a single symbol configuration and up to 12 orthogonal ports for a dual symbol configuration, which may make DMRS configuration type 2 more suitable for MU-MIMO.

[0106] In conjunction with MIMO, to enhance coverage, reliability, and throughput, enhancements for uplink transmissions may be considered for certain classes of WTRUs. DMRS enhancements may be employed to support the following features.

[0107] A first feature may be to specify a larger number of orthogonal DMRS ports for downlink and uplink MU-MIMO (e.g., with or without increasing DM-RS overhead) for use, e.g., only for CP-OFDM. This feature may seek to achieve a common design between DL DMRS and UL DMRS. This feature may employ up to, e.g., 24 orthogonal DM-RS ports, where for each applicable DMRS type, the maximum number of orthogonal ports may be doubled for both single-symbol DMRS and dual-symbol DMRS.

[0108] A second feature may be to specify UL DMRS, SRS, SRI and TPMI (including codebook) enhancements to enable 8Tx UL operation to support 4 layers and more per WTRU in the UL for CPE / FWA / vehicle / industrial equipment. Potential limitations on the scope of this feature may be identified (including, for example, coherence assumptions, full / non-full power modes).

[0109] A third feature may be to specify the following items to facilitate simultaneous multi-panel UL transmission for achieving higher UL throughput / reliability, focusing on FR2 and multiple TRPs, assuming up to 2 TRPs and up to 2 panels, and for CPE / FWA / vehicles / industrial equipment (if applicable). Features may include providing UL pre-coding indications for PUSCH, where no new codebooks may be introduced for simultaneous transmission of multiple panels. Considering multi-TRP operation based on single DCI and multiple DCI, the total number of layers across all panels may be up to four and the total number of codewords across multiple panels may be up to two. The feature may provide UL beam indications for PUCCH / PUSCH, where considering multi-TRP operation based on single DCI and multiple DCI, the unified TCI framework extension in target 2 may be assumed. For multi-TRP operation based on multiple DCI, PUSCH+PUSCH (e.g., only PUSDH+PUSCH) or PUCCH+PUCCH may be transmitted across two panels in the same CC.

[0110] Disclosed herein are DMRS enhancements. DMRS enhancements may involve, for example, increasing the number of ports, supporting simultaneous multi-panel transmissions, and / or supporting 8TX WTRUs. The disclosed DMRS enhancements include procedures for cross-panel DMRS interference management. Cross-panel DMRS interference management may involve, for example, solutions for cross-panel DMRS pairing and orthogonal / non-orthogonal mapping. The disclosed DMRS enhancements may include procedures for enhanced OCC mapping. Enhanced OCC mapping may involve the use of shared / overlapping OCCs. The disclosed DMRS enhancements may include procedures for increasing the number of DMRS ports. Increasing the number of DMRS ports may, for example, involve new DMRS mapping modes for SU / MU MIMO.

[0111] Procedures for cross-panel DMRS interference management may be provided. DMRS interference management may involve inter-panel DMRS pairing. The WTRU may receive a grant that schedules a PUSCH transmission and its associated DMRS. The grant may include a field indicating the antenna port configuration for the WTRU. In the case of a single DCI (sDCI), the WTRU may receive one antenna port field. If a single TRP is used, the WTRU may determine that the antenna port may be associated with a DMRS transmission to one TRP. If multiple TRP (mTRP) repetitions are scheduled, the WTRU may determine that the same antenna port configuration may be used for transmissions toward two TRPs. If TDM transmissions are used, the PUSCH transmissions may include repetitions scheduled at different time instances (e.g., symbols or time slots). The WTRU may be able to use more than one panel to send PUSCH toward more than one TRP simultaneously in the same time slot or symbol. We may denote this mode of operation as simultaneous multi-panel (SMP).

[0112] The WTRU may receive an sDCI with more than one antenna port field, where for SMP, each antenna port field may be independently configured per WTRU panel. The WTRU may determine the antenna port per panel based on the ordering of the antenna port fields in the DCI. For example, a first antenna port may be associated with a first panel, TCI, or PMI, and a second antenna port may be associated with a second panel, TCI, or PMI.

[0113] The WTRU may determine that a single antenna port field may be associated with more than one panel. If the WTRU determines that the grant is scheduling the WTRU in SMP mode (e.g., explicitly or indicated by SRI / TCI, TPMI / PMI), the WTRU may determine that a first set of ports may be associated with a first panel and a second set of ports may be associated with a second panel. The WTRU may receive a DMRS port indication {0,1} and an explicit bit field flag in the grant indicating an SMP mode of operation. The WTRU may use port 0 for the first antenna panel and may use port 1 for the second antenna panel.

[0114] The reserved fields from the antenna port indication (e.g., values ​​12-15) may be reused to indicate the SMP mode of operation. The WTRU may choose to transmit under SMP when it receives a grant indicating these values. Each value may be mapped to a different antenna port combination and assignment per panel (e.g., SMP with port 0 panel 0 and port 1 panel 1; SMP with port 0-1 panel 0 and port 2 panel 1, etc.).

[0115] The WTRU may receive a MAC-CE or UL-TCI which may include an indication of a DMRS port pair for SMP. The WTRU may use the indication of the SMP DMRS port pair in addition to the antenna port indication to determine whether the PUSCH is scheduled in SMP mode and the port assignment per panel. The WTRU may receive an antenna port indication to use port 0 and port 1. The WTRU may receive an indication that port 0 and port 1 may be paired for SMP. The WTRU may transmit port 0 and port 1 simultaneously on panel 0 and panel 1, respectively.

[0116] In multi-DCI mode (mDCI), the WTRU may receive separate DCIs, each of which may be transmitted from a different TRP. The WTRU may receive a separate antenna port indication from each grant. An additional field may be included as part of the antenna port indication to indicate whether SMP scheduling is performed between antenna ports. For example, if the WTRU receives an antenna port 0 indication for panel 0, an antenna port 1 indication for panel 1, and a bit indicating SMP, the WTRU may determine to transmit in SMP mode. The WTRU may receive resource assignments in time / frequency that may partially overlap (e.g., may only overlap) between two mDCIs. The WTRU may choose to perform SMP (e.g., only) when the resource assignments overlap.

[0117] DMRS mapping for SMP may be provided. The WTRU may be instructed to use rate matching to achieve the desired decoding sequence length. For example, the WTRU may map its PUSCH transmissions to a set of REs, except for rate-matched REs (i.e., skipped REs) in which the WTRU does not transmit. The WTRU may need to omit some decoding bits from the output of the channel decoder. The omitted bits may be defined as truncation from the sequence. Different truncation patterns may be configured to reduce interference to rate-matched REs on the uplink or downlink. In the SMP mode of operation, inter-panel interference may also be considered, and rate matching patterns may be used to mitigate interference.

[0118] The WTRU may determine different rate matching modes based on its panel orthogonality. The WTRU may consist of one or more antenna panels, and the antenna panels may have different orientations. For example, one antenna panel may point outward from the front of the device, while another antenna panel may point outward from the back of the device. These directions may be quasi-orthogonal from an associated interference perspective because the spatial filters may point in opposite directions. The WTRU may be able to transmit simultaneously from two of these panels that have low inter-panel interference. If this is the case, the WTRU may not perform rate matching around the PUSCH resources of the other panels.

[0119] The WTRU may indicate as part of its capabilities a panel pair with low inter-panel interference. The WTRU may also indicate this as part of the CSI report with an associated CRI index per panel. For example, panel 1 and panel 2 may have low inter-panel interference. Based on this capability, the WTRU may be scheduled to transmit on panel 1 and panel 2 simultaneously.

[0120] The WTRU may determine which panels are orthogonal based on the timing advance (TA). The WTRU may determine that the two panels are orthogonal if the difference between the TAs of the two panels is less than a threshold, and non-orthogonal otherwise.

[0121] The WTRU may receive a configuration of a DMRS with more than one scrambling ID. The DMRS sequence may be generated using a scrambler with a seed initiated by the scrambling ID. If the panels are not orthogonal, the WTRU may select two different scrambling IDs and may apply one scrambling ID per DMRS sequence used per panel to further reduce inter-panel interference. Otherwise, the WTRU may reuse the same scrambling ID for both panels.

[0122] The WTRU may determine rate matching based on the panel orthogonality. If the panels are orthogonal, the WTRU may determine that rate matching is not applied; otherwise, the WTRU may perform rate matching. The WTRU may include an indication in the UCI whether the WTRU applies rate matching and which antenna ports / CDM groups the WTRU applies to. The WTRU may indicate CDM grouping preferred for SMP as part of the WTRU capabilities or as part of a MAC-CE for SMP where the WTRU may indicate panel pairing / association to the network. Alternatively, when different panels are considered, the WTRU may receive a pre-configured rate matching pattern. The rate matching pattern may be defined based on the OCC pattern or CDM group used for SMP.

[0123] When the WTRU is scheduled in SMP mode, the WTRU may determine to rate match a PUSCH transmission around the DMRS of another simultaneous PUSCH transmission. The WTRU may determine two different DMRS allocations, each DMRS allocation being associated with a respective panel. The WTRU may receive a rate matching pattern that the WTRU may apply, for example, only when transmitting in SMP mode. Alternatively, the WTRU may indicate a port pair that may be used for SMP and may indicate the rate matching pattern that the WTRU is using. The ports may belong to the same or different CDM groups.

[0124] Extended DMRS transmission may be provided. To increase the capacity of a transmission port (e.g., a DMRS port), the DMRS port may be divided into more than one group, wherein a first set of DMRS ports may transmit in a first scheduled time slot, and a second set of DMRS ports may transmit in a second scheduled time slot, etc. Figure 3 An example of extending a DMRS port over several time slots is depicted. Figure 3 In the example depicted in , to support 24 DMRS ports with an OCC length of 2, a first set of 12 DMRS ports may be transmitted in a first time slot, and a second set of DMRS ports may be transmitted in a second time slot. For a given port, the mapping of DMRS in the frequency domain may change in each transmission.

[0125] The WTRU may receive an indication / configuration that DMRS RE locations (and / or phase tracking RS (PTRS) RE locations) may be changing (e.g., being offset based on a preconfigured / predefined pattern) across PUSCH transmission instances, wherein each of the PUSCH transmission instances may be scheduled based on receiving the same codepoint of a DMRS-related field (e.g., an "antenna port" field) in a DCI that schedules each of the PUSCHs (and / or based on receiving the same second codepoint of a PTRS-related field (e.g., a "PTRS-DMRS association" field). In an example, the WTRU may (e.g., may be configured to) transmit DMRS (only) on a selected subset of DMRS ports that may be defined per RB and / or timeslot, e.g., based on the indication / configuration. The WTRU may determine the DMRS port for transmission based on the uplink antenna port indication in the scheduling DCI. Based on the determined DMRS port for transmission, the WTRU may determine (e.g., update) an association of a PTRS port with at least one of the determined DMRS ports.

[0126] The code point may be preconfigured by RRC and / or activated by MAC-CE, for example, thereby indicating / including at least one DMRS antenna port in a certain number of DMRS antenna ports that may correspond to the total number of PUSCH layers. Each DMRS port number may correspond to each PUSCH layer in the PUSCH layer, the number of DMRS CDM groups without data, and the number of front load symbols, etc., where the number of DMRS antenna ports may be indicated by separate fields (e.g., precoding information and number of layers field). The second code point of the PTRS related field may be preconfigured by RRC and / or activated by MAC-CE, for example, thereby indicating the association between the PTRS port and the DMRS port.

[0127] The WTRU may determine, at a first PUSCH transmission instance in a PUSCH transmission instance (e.g., scheduled by a first DCI that schedules the first PUSCH), first one or more DMRS RE locations corresponding to each DMRS port number indicated by code point C in a field of the first DCI (e.g., the "antenna port" field), and / or first one or more PTRS RE locations indicated by code point D in a PTRS-related field. In response to the determination, the WTRU may transmit a first PUSCH and a DMRS and / or PTRS (associated with or together with the first PUSCH) based on the first one or more DMRS RE locations and / or the first one or more PTRS RE locations.

[0128] In response to receiving an indication / configuration that DMRS / PTRS RE positions may be changing across PUSCH transmission instances, the WTRU may determine, at a second PUSCH transmission instance in the PUSCH transmission instance (e.g., scheduled by a second DCI that schedules a second PUSCH), a second one or more DMRS RE positions corresponding to each DMRS port number indicated by (e.g., the same) code point C in a field (e.g., the "antenna port" field) of the second DCI, and / or a second one or more PTRS RE positions indicated by (e.g., the same) code point D in a PTRS-related field. In response to the determination, the WTRU may transmit a second PUSCH and a DMRS and / or PTRS (associated with or together with the second PUSCH) based on the second one or more DMRS RE positions and / or the second one or more PTRS RE positions. The second one or more DMRS RE positions may be determined based on the indication / configuration as a frequency-domain offset version of the first one or more DMRS RE positions (e.g., offset up or down by X-REs, e.g., X=1, 2, ... or X_max). The parameter / value of X may be indicated or configured to the WTRU. The second one or more PTRS RE locations may be determined as a frequency domain offset version of the first one or more PTRS RE locations based on the indication / configuration (e.g., offset up or down by P-RE, e.g., P=1, 2, ... or X_max). A parameter / value of P may be indicated or configured to the WTRU. X and P may be the same / identical (or indicated using a single parameter), for example, based on the indication / configuration.

[0129] In response to receiving an indication / configuration that DMRS / PTRS RE positions may be changing across PUSCH transmission instances, the WTRU may determine, at a third PUSCH transmission instance in the PUSCH transmission instance (e.g., scheduled by a third DCI that schedules a third PUSCH), a third one or more DMRS RE positions corresponding to each DMRS port number indicated by (e.g., the same) code point C in a field (e.g., the "antenna port" field) of the third DCI, and / or a third one or more PTRS RE positions indicated by (e.g., the same) code point D in a PTRS-related field. In response to the determination, the WTRU may transmit a third PUSCH and a DMRS and / or PTRS (associated with or together with the third PUSCH) based on the third one or more DMRS RE positions and / or the third one or more PTRS RE positions. In an example, the third one or more DMRS RE positions may be determined as a frequency domain offset version of the first (or second) one or more DMRS RE positions (e.g., offset up or down by Y-REs, e.g., Y=1, 2, ... or Y_max) based on the indication / configuration. The parameter / value of Y may be indicated or configured to the WTRU. The third one or more PTRS RE positions may be determined as a frequency domain offset version of the first (or second) one or more PTRS RE positions based on the indication / configuration (e.g., offset up or down by Q-RE, e.g., Q=1, 2, ... or Q_max). The parameter / value of Q may be indicated or configured to the WTRU. Y and Q may be the same / identical (or indicated as a single parameter), for example, based on the indication / configuration.

[0130] X and Y may be the same / identical (or indicated using a single parameter), for example, based on the indication / configuration. P and Q may be the same / identical (or indicated using a single parameter), for example, based on the indication / configuration. For example, based on the indication / configuration, the third one or more DMRS (and / or PTRS) RE positions may be the same (e.g., identical) as the first one or more DMRS (and / or PTRS) RE positions, which may imply that there are two alternating patterns in the DMRS (and / or PTRS) RE positions across PUSCH transmission instances in the following example order: first one or more DMRS (and / or PTRS) RE positions; second one or more DMRS (and / or PTRS) RE positions; first one or more DMRS (and / or PTRS) RE positions; second one or more DMRS (and / or PTRS) RE positions; and so on.

[0131] A gNB (or a second WTRU, e.g., in a sidelink) receiving at least DMRS (and / or PTRS) transmitted at a first one or more DMRS (and / or PTRS) RE locations and a second one or more DMRS (and / or PTRS) RE locations across a PUSCH transmission instance may apply (e.g., in time / frequency domain) interpolation for wireless channel estimation (and / or phase tracking of a channel) based at least on the DMRS (and / or PTRS) across the PUSCH transmission instance, and for receiving at least one of the first PUSCH, the second PUSCH, and the third PUSCH, etc. This may improve uplink performance (e.g., in terms of UL throughput and / or reliability) based on the effect of increasing the DMRS (and / or PTRS) density (e.g., in the frequency domain) across the PUSCH transmission instance according to a frequency domain offset version of at least the DMRS, which may improve wireless channel estimation performance.

[0132] DMRS mapping with overlapping OCCs may be provided. OCCs may be used to support multiplexing of transmit ports for reference signals. Figure 4 An example use case of multiplexed OCCs for 4 DMRS ports is depicted. An example of an OCC with length 4 and no overlapping OCCs is shown. There may be no overlap of OCCs applied on different resources and the same OCC group may be used for the entire scheduling band. A disadvantage of this design may be that it may not always be possible to have a self-contained RB with an OCC. Figure 4 As shown, while the first OCC may be completely within the first scheduled RB, the second OCC may not be within the first scheduled RB and the second OCC may be extended to adjacent RBs. Therefore, if the WTRU is not scheduled to have adjacent RBs, some of the DMRS may not be able to be used for channel estimation.

[0133] Multi-port reference signals may be multiplexed using overlapping OCCs. A WTRU may transmit multi-port reference signals using overlapping OCCs. A WTRU may receive multi-port reference signals using overlapping OCCs.

[0134] Figure 5 The basic principle of overlapping OCC for multi-port DMRS is illustrated. Figure 5 , an OCC with length 2 is presented. The presented concept is equally applicable to other OCC lengths. The presented principles can be used for a variety of other purposes, including, for example, the following: multiplexing and sending other types of signals (e.g., CSI-RS, etc.); multiplexing signals in other domains (e.g., time domain, etc.); uplink transmission or downlink transmission; and / or cross-panel, cross-TRP port mapping, etc.

[0135] like Figure 5As illustrated, more than one OCC group may be used. A first group of OCCs may span a first set of resource elements, and a second group of OCCs may span a second set of resource elements. Some resource elements may be covered by more than one cover code, where for the same transmit port, the cover code coefficients used by different OCC groups on shared resource elements may be the same. For example, Figure 5 As shown, at the shared location RE2, for each DMRS port, the OCC coefficient used by the two groups is the same, for example, +1 for group 1 and -1 for group 2.

[0136] like Figure 5 As shown, assuming equal channels on adjacent REs, the estimated channel for each DMRS port can be estimated as indicated in the following diagram:

[0137]

[0138] Figure 6 An example of DMRS mapping using overlapping OCC length 4 is shown. Figure 4 In contrast to the mapping shown, it is not necessary to schedule more than one RB to enable OCC mapping of all DMRS within a given RB. Figure 6 As shown, each RB may contain two overlapping OCCs, and it may not be necessary to group DMRS REs of different RBs to be able to perform complete channel estimation. It should be understood that although the text mentions DMRS mapping with overlapping OCCs, the disclosed concept for performing DMRS mapping may also be applicable to, for example, overlapping CDM groups.

[0139] Enhanced DMRS mapping may be provided. PDSCH and PUSCH (e.g., without transform precoding) DMRS design modes may support up to 12 orthogonal antenna ports for SU / MU-MIMO transmission. To improve MIMO transmit system capabilities, DMRS design enhancements to support more orthogonal ports without increasing DMRS overhead in existing NR architectures may be useful. PDSCH (or PUSCH) DMRS configuration modes for CP-OFDM waveforms may be considered that support up to 24 orthogonal DMRS ports.

[0140] The WTRU may receive a configuration of a DMRS in which the number of ports may be greater than 12. The WTRU may determine a pattern for DMRS transmission based on the received DMRS configuration. The WTRU may transmit the DMRS based on one of the patterns discussed herein.

[0141] A first example mode ("Mode 1") may correspond to Figure 7 The depicted DMRS mapping for a CP-OFDM waveform. A second example mode ("Mode 2") may correspond to Figure 8 Depicted DMRS mapping for CP-OFDM waveform. The number of REs allocated per OFDM symbol for DMRS pilots can be reduced to accommodate scenarios where DMRS configuration type 1 and DMRS configuration type 2 need to support more than 12 orthogonal DMRS ports. Figure 7 and Figure 8 In the proposed DMRS Pattern 1 and DMRS Pattern 2 shown in FIG, the number of REs per OFDM symbol is reduced to 2 REs to support up to 24 orthogonal DMRS ports. OCCs may be used to support multi-port operation. Depending on the DMRS configuration, the WTRU may send DMRS using a length 2-OCC for a single symbol or a length 4-OCC for a dual symbol DMRS configuration. Thus, DMRS Pattern 1 and DMRS Pattern 2 may support up to 12 orthogonal DMRS ports for a single symbol configuration and up to 24 orthogonal DMRS ports for a dual symbol configuration.

[0142] The WTRU may receive a semi-static or dynamic first configuration, which may include a configuration for a specific OCC length. The WTRU may receive, for example, a configuration for a length of 2-OCC. Figure 7 and Figure 8 As shown, the spacing between the first RE and the second RE of the OCC may be different. The WTRU may determine the spacing between REs of the OCC pattern based on a dynamic indication. The WTRU may receive a dynamic indication, such as a MAC CE or a DCI, to implicitly or explicitly indicate the spacing of REs within the configured OCC. For example, the WTRU may receive a dynamic indication to assume that Figure 7 Indication of the spacing of the 6 REs shown.

[0143] A third example mode ("Mode 3") may correspond to Fig. 9 The depicted DMRS mapping for a CP-OFDM waveform. A fourth example mode ("Mode 4") may correspond to Fig.10 Depicted DMRS mapping for a CP-OFDM waveform. Fig. 9 and Fig.10 An OCC with a longer length is illustrated, which can be considered as a mechanism to increase the number of orthogonal DMRS ports in different use case scenarios. For single-symbol DMRS configurations in DMRS Mode 3 and DMRS Mode 4, four antenna ports using the same RE can be orthogonalized by using a length 4-OCC. Conversely, for dual-symbol DMRS configurations, 8 antenna ports sharing the same RE are orthogonalized using a length 8-OCC. DMRS Mode 3 and DMRS Mode 4 can support up to 12 orthogonal DMRS ports for single-symbol configurations and up to 24 orthogonal DMRS ports for dual-symbol configurations.

[0144] An example pattern may include overlapping OCCs. Fig.11 Depicted is an example single symbol 6-port DMRS mapping for a CP-OFDM waveform using overlapping OCCs of length 4. The WTRU may be configured to transmit or receive DMRS on 12 different DMRS ports using this pattern, where REs illustrated using dark shading may be utilized for a first set of 6 ports, and REs illustrated in white may be utilized for a second set of 6 ports. By employing two (2) symbols, and following the principles presented, the overall DMRS capacity may be increased to 24 ports.

[0145] exist Fig.11 , an exemplary set of OCC codes for each port is shown. Other OCC codes may also be used.

[0146] The WTRU may use an OCC set where the elements of each overlapping OCC may be the same on the overlapping REs. Fig.11 , the second element of the OCC associated with port 1 and port 2 may be the same as the first element of the OCC associated with port 3 and port 4.

[0147] In a similar Fig.11 In an alternative mapping of , for the last element of the OCC, we can go to the next RB or wrap around to the first pilot position.

[0148] for Fig.11 The exemplary 6-port DMRS mapping shown in FIG. 1 can calculate the channel estimate h for each port based on the measurement at each DMRS position. i ,

[0149]

[0150] where C is the matrix containing the covering code. Fig.11 The example shown,

[0151]

[0152] for Fig.11 For the mapping in , other examples of the cover code matrix C can be considered, for example,

[0153]

[0154] in

[0155]

[0156] Fig.12An example single symbol DMRS is depicted to support 12-port DMRS mapping using overlapping OCCs with length 4. The WTRU may be configured to transmit or receive DMRS on 12 different DMRS ports using this pattern. By employing two (2) symbols, and following the principles presented, the overall DMRS capacity may be increased to 24 ports.

[0157] Enhanced accuracy channel estimation can be provided. The capacity of the DMRS port configuration can be increased by increasing the length of the cover code in time or frequency. However, the accuracy of the estimate can be reduced by the assumption that the channel does not change or changes very little during the duration of the cover code. The accuracy of the channel estimate can be enhanced by considering a sliding window over several DMRS transmissions. Fig.13 The operation of a sliding window for enhancing channel estimation is illustrated, where each OCC group indicated by the dashed ellipse may have two estimates produced by the first estimation window and the second estimation window, instead of one estimate. The overall estimate may be enhanced by further processing such as, for example, averaging the two available estimates. The step for sliding the window may be one or more REs.

[0158] In an example implementation employing DMRS mapping using overlapping cover codes, where y, C, and h represent the received DMRS RE, cover code matrix, and channel per port for a given estimation window, respectively, y = Ch. Fig.13 In the example depicted in FIG. 1 , the first estimate and the second estimate from the first estimation window and the second estimation window may be calculated by: h1=C1 - 1 y、h2=C2 -1 y, where C1 and C2 may be covering code matrices corresponding to the first estimation window and the second estimation window.

[0159] In an example with N estimation windows, the WTRU may estimate N estimates for each port if (eg, only if) all cover code matrices C1, C2, ..., CN corresponding to the N estimation windows are invertible.

[0160] For example, for Fig.11 The two exemplary C matrices presented support this feature.

[0161]

[0162] but

[0163]

[0164] Where C2 -1 Evaluated as

[0165]

[0166] The WTRU may be configured to provide enhanced DMRS indications. The WTRU may be configured by RRC with a DMRS type (e.g., a specific DMRS type), a configuration (such as, for example, Type I, Type II, etc.). The WTRU may receive dynamic indications to determine the mapping type (e.g., A or B), the assigned DMRS ports, etc. for the scheduled transmission.

[0167] The WTRU may receive a semi-static configuration for a P (e.g., P=24) port DMRS configuration, wherein the configuration information includes one or more mapping attributes required for defining the P port mapping in the time domain, frequency domain, and spatial domain, such as information about frequency mapping, time mapping, cover codes, etc.

[0168] The WTRU may receive a dynamic indication, such as a DCI or a MAC CE, based on which the WTRU may explicitly or implicitly determine and select a subset of DMRS ports for transmission from the P configured DMRS ports. The dynamic indication may include information about one or more of the following: frequency and time mapping of resource elements (e.g., subcarriers, symbols, time slots, etc.) used for DMRS transmission; information elements (e.g., indices) for determining cover codes for multiplexing multiple DMRS ports; information elements (e.g., indices) for determining transmit beams; information elements (e.g., indices) for determining associated panels for DMRS transmission, such as information elements (e.g., indices) identifying panels for UL transmission or for DL ​​reception; information elements (e.g., indices) for determining DMRS power offsets relative to main transmissions (e.g., PDSCH, PUSCH, etc.); an indication of whether rate matching is to be performed around an indicated subset of P ports or all configured P ports; an indication of determining OCC-related information (e.g., length, sequence, etc.); an indication of determining timing information required for UL transmission (e.g., TA); an indication of identifying a DMRS sequence initialization seed for the indicated port; and an indication of determining a PTRS association for the dynamically indicated port. In an example where the dynamic indication includes an information element to determine the transmit beam, for PDSCH DMRS, multiple TCI information may be configured for the configured P ports. The WTRU may receive an index to select one of the configured TCIs for DMRS reception. In another example where the dynamic indication includes an information element, for PUSCH DMRS transmission, multiple SRIs may be configured for the configured P ports. The WTRU may receive an index to select one of the configured uplink beams for DMRS transmission.

[0169] Fig.14An example of dynamic DMRS port indication and selection is depicted. A single symbol DMRS mapping including 6 groups of 2-port DMRS (each with a cover code of length 2) may be configured to support 12 DMRS ports. With each dynamic indication, which may be a DCI, for example, the WTRU may select a different set of ports for transmission for each transmission.

[0170] The WTRU may receive a first configuration via RRC to support P (e.g., P=24) port DMRS operation, wherein the configuration information includes one or more mapping attributes required to define P port mapping in the time domain, frequency domain, and spatial domain, such as information about frequency mapping, time mapping, cover code, etc. The WTRU may further receive a DCI including information related to the DMRS port.

[0171] For CP-OFDM transmissions, up to 5 bits and 6 bits may be used in the scheduling DCI to indicate the DMRS ports for uplink transmissions and downlink transmissions, respectively, where in either case, not all code points may be used. The WTRU may use one or more of the reserved code points / states in the received DCI (e.g., DCI fields for antenna port indication) to determine whether the DMRS ports indicated by the DCI may be based on the legacy P-port DMRS configuration or the enhanced P-port DMRS configuration.

[0172] If a WTRU that can be configured with DMRS mapping (e.g., legacy DMRS mapping, (e.g., dmrs-Type=1, maxLength=1, where 4 bits are allocated for antenna port indication)) and enhanced DMRS configuration via RRC receives DCI format 1_1, the WTRU can determine whether the DMRS antenna port field indicates legacy mapping or enhanced mapping by checking one or more of the reservation states (e.g., states 12-15) in the antenna port.

[0173] Once the WTRU determines that the indicated DMRS port is from the enhanced DMRS configuration, the WTRU may interpret the content of the antenna port indication field in the decoded DCI according to the enhanced DMRS configuration mapping.

[0174] The WTRU may use one or more of the following to determine whether the DMRS port indicated by the DCI may be based on the legacy P-port DMRS configuration or the enhanced P-port DMRS configuration: RRC configuration to semi-statically configure the enhanced DMRS configuration; MAC CE to activate / deactivate the enhanced DMRS configuration, or alternatively activate DMRS enhancement mapping based on a counter or for a preconfigured duration; WTRU capability, for example, when the WTRU declares the use of 8 TX antennas for uplink transmission; and an implicit indication based on another operating / configuration parameter or mode (e.g., mobility, multi-user operating mode, cell ID, etc.).

[0175] The WTRU may be configured to provide enhanced CDM grouping. A CDM group may be associated with an antenna port. A CDM group may be used to multiplex one or more DMRS ports in the code domain, wherein an orthogonal cover code may be used to multiplex one or more DMRS ports in the code domain. A CDM group may multiplex up to N DMRS ports. If the total number of DMRS ports (Ntot) may be greater than N (e.g., Ntot>N), more than one CDM group may be used. For example, if Ntot=2N, two CDM groups may be used to multiplex 2N DMRS ports. The time / frequency resources used for a CDM group may be mutually exclusive with the time / frequency resources used for another CDM group.

[0176] A set of DMRS ports may be configured, determined, or used for data transmission / reception (e.g., PDSCH, PUSCH), and one or more PTRS ports may be configured, determined, or used together with the set of DMRS ports. The presence / absence and / or mode of PTRS may be determined based on at least one of scheduling information (e.g., scheduling bandwidth, MCS, and waveform types including OFDM and DFT-s-OFDM).

[0177] The WTRU may determine the number of PTRS ports for data transmission / reception (e.g., PDSCH or PUSCH) based on one or more characteristics of a set of DMRS ports associated with data transmission / reception. The set of DMRS ports associated with data transmission / reception may be the DMRS ports used, determined, or selected for data transmission / reception for a given number of determined layers. The one or more characteristics of the set of DMRS ports may include at least one of the following: DMRS type (e.g., type 1, type 2); the number of CDM groups associated with the set of DMRS ports determined, used, or selected for data transmission / reception; DMRS density; DMRS pattern; CDM groups without data; EPRE ratio between DMRS and PDSCH / PUSCH RE; or antenna coherence level (complete / partially coherent, incoherent). The number of PTRS ports may be the same as the number of CDM groups associated with the set of DMRS ports for data transmission / reception.

[0178] A PTRS port may be associated with a DMRS port group. Thus, a phase error (e.g., a common phase error) measured from a PTRS port may be compensated for data using a DMRS port in the group that is associated with the PTRS port. A DMRS port group may be determined based on DMRS ports associated with the same CDM group. For example, in DMRS type 1, DMRS ports {1, 2, 3, 4} may be associated with a first CDM group, and DMRS ports {5, 6, 7, 8} may be associated with a second CDM group, wherein a first PTRS port may be associated with a DMRS port in the first CDM group, and a second PTRS port may be associated with a DMRS port in the second CDM group.

[0179] A PTRS port may be associated with a DMRS port within a DMRS port group for phase error (e.g., common phase error) estimation and / or channel estimation. For example, the WTRU may perform phase error estimation by using the PTRS and the corresponding DMRS associated with the PTRS. In another example, the WTRU may perform channel estimation by using the DMRS and the corresponding PTRS. The DMRS port associated with the PTRS port in the DMRS port group may be determined based on at least one of: a DMRS port with a lowest DMRS index within the group; and / or a DMRS port with the strongest power within the group, wherein the strongest power may be based on a modulation order (or MCS) determined for the DMRS port.

[0180] The DMRS port group may be determined based on the DMRS ports associated with the same antenna panel or antenna group. The WTRU may report its capabilities related to the antenna panel and its associated DMRS ports after the initial access procedure (e.g., during RRC connection establishment), where the DMRS ports associated with the same antenna panel may be indicated as an antenna group.

[0181] The DMRS port groups may be determined based on the antenna coherence at the WTRU (e.g., full / partial coherence, incoherence). For example, if the WTRU may have fully coherent antennas (or may be indicated as having fully coherent antennas as a capability), the DMRS port groups may be all DMRS ports that are configured or used. If the WTRU may have partially coherent antennas (or may be indicated as having partially coherent antennas as a capability), the DMRS port groups may be based on the DMRS ports associated with the CDM groups. If the WTRU may have incoherent antennas (or may be indicated as having incoherent antennas as a capability), each DMRS port may be determined as a group.

[0182] An indication of a CDM group may be provided. The WTRU may indicate a set of configured DMRS ports as being associated with a PTRS port. The configured DMRS ports may belong to the same or different CDM groups. For example, if the WTRU receives a configuration for DRMS ​​type 1, a subset of the configured DMRS ports may belong to CDM group 0 or group 1. Additionally, if the WTRU may be configured with DRMS ​​type 2, a subset of the DMRS ports may belong to CDM groups 0, 1, or 2. The WTRU may use the CDM group to determine the DMRS port associated with the PTRS port. The set of configured DMRS ports for PTRS-DMRS association may be from the same CDM group.

[0183] If PTRS transmission is configured, the WTRU may receive a configuration indicating a CDM group mapping of DMRS ports associated with one or more of the PTRS ports for data transmission / reception. This configuration may include a list of different CDM group mappings, where each mapping may be assigned a code point (i.e., bit). The WTRU may receive a DCI that may include a bit field to indicate the code point corresponding to each mapping. An option may be to reuse an existing bit field in the DCI to indicate the CDM group mapping. For example, in a DCI for uplink transmission, a bit (e.g., up to 5 bits) may be used for DMRS antenna port indication. Some of the code points may be unused and may be used to indicate different CDM group mappings. The WTRU may determine the CDM group of the DMRS port associated with the PTRS port by checking one of the reserved code points in the antenna port field of the DCI. The WTRU may transmit the PTRS together with a set of DMRS ports, where the set of DMRS ports may be mapped to the indicated CDM group.

[0184] The WTRU antenna layout may be divided into antenna panels or antenna groups, where each antenna group includes a subset of the WTRU antennas. Each antenna group may consist of the same or different number of TX antennas. The WTRU may receive a configuration where the DMRS ports associated with the PTRS ports for each antenna group may be from the same CDM group.

[0185] Existing fields in the DCI may be used to indicate the CDM group mapping for the DMRS ports associated with the PTRS port. For example, the PTRS-DMRS Association field in the DCI may be used for CDM group indication, where each codepoint is assigned a CDM group (e.g., 0→CDM 0, 1→CDM 1, 2→CDM 2, 3→Reserved). The WTRU may receive a DCI with an indication of a CDM group and then transmit the PTRS with one of the DMRS ports from the indicated CDM group. For example, if a value of 0 may be indicated in the PTRS-DMRS Association DCI field, the DMRS associated with the PTRS port may be mapped to CDM group 0, and the WTRU may transmit the PTRS with the DMRS ports of CDM group 0.

[0186] The WTRU may receive a configuration in which each antenna group may be mapped to a different CDM group. The configuration may include a list of all possible combinations of CDM group to antenna group mappings. The WTRU may receive an indication of the CDM group for each antenna group in the DCI, and then the WTRU may send a PTRS on one of the DMRS ports of the indicated CDM group for each antenna group. For example, some reserved code points in the antenna port DCI field may be used to indicate the CDM group assignment, where each code point contains one of the possible combinations of CDM group to antenna group mappings. In DMRS Type 1, in the case of 2 antenna groups, the reserved code points may have their input as "01", where a rule may be assigned such that a first number indicates that a DMRS port in the first antenna group may be mapped to CDM group 0, and a second number may indicate that a DMRS port in the second antenna group may be mapped to CDM group 1.

[0187] Enhanced DMRS mapping may be provided. Enhanced DMRS mapping may be associated with MU-MIMO transmission. OCC may be used to support transmit port multiplexing associated with reference signals. In NR DMRS design, OCC length 2 may be used to multiplex DMRS ports so that OCC pairing may be within a single RB. To support a higher number of DMRS ports, OCC length 4 may be used. Since there may be 6 DMRS REs per PRB using type 1 DMRS configuration, if OCC length 4 is used, the first DMRS RE may be covered by the first OCC, while the last two remaining DMRS REs may be bundled with the first DMRS RE of the adjacent PRB to complete the next OCC mapping set. If a longer length (e.g., length 4) OCC may be used, the problem of orphan resource elements (REs) may occur, i.e., if the number of REs used for DMRS within a resource block may not be a multiple of the OCC length, remaining unmapped REs may occur. For MU-MIMO transmission, if 2 or more WTRUs may be scheduled to have two different starting PRBs, the problem of orphan REs may exist.

[0188] Fig.15 Depicted are example cases of MU-MIMO transmission with and without FD offset for OCC mapping. Fig.15 , at section (a), an exemplary case of a MU-MIMO transmission configured with DMRS type 1 with FD-OCC length 4 may be depicted. Two WTRUs, each configured with two (2) DMRS ports, may be scheduled to have the same starting PRB for their PDSCH resource mappings. Thus, the OCC mappings for the co-scheduled WTRUs may be aligned (e.g., fully aligned) to enable proper orthogonalization of the DMRS ports associated with the two WTRUs.

[0189] refer to Fig.15 , at section (b), another exemplary case of MU-MIMO transmission configured with DMRS type 1 with FD-OCC length 4 may be depicted. Two WTRUs, each configured with two (2) DMRS ports, may be scheduled to have different starting PRBs for their PDSCH resource mappings. Fig.15 As shown, at segment (b), the starting PRB for scheduled transmissions of WTRU 1 is at PRB 0, while the starting PRB for scheduled transmissions of WTRU 2 is at PRB 1. Since the PDSCH allocations may be misaligned due to different starting PRBs, the OCC may be mismatched and may not be used for orthogonalization of DMRS ports.

[0190] refer to Fig.15 , at section (c), when the starting PRBs of the scheduled PDSCH transmissions may not be the same or separated by an even number of PRBs, an exemplary solution may be depicted for the case of a MU-MIMO transmission configured with DMRS type 1 with FD-OCC length 4. To properly orthogonalize and separate the DMRS ports, the starting RE of the OCC of one of the WTRUs may be offset by half the length of the OCC. Fig.15 As shown, at segment (c), when the starting PRB for the scheduled transmission of WTRU 2 may be at PRB 1, the start of the complete OCC in PRB 1 may be at the third DMRS RE. As a result of this offset, the remaining set of OCCs may be aligned, e.g., fully aligned.

[0191] If the WTRU may be configured with an FD-OCC length that results in some orphaned REs, the WTRU may use an FD offset version of the OCC map to align its mapping with another scheduled transmission. The WTRU may determine whether to perform an FD offset based on one or more of several implementations, such as the usefulness or necessity of performing an FD offset. In a first implementation for determining whether to perform an FD offset, the WTRU may receive a dynamic indication to offset the OCC mapping for a scheduled transmission. The indication may be received as part of the scheduling DCI or separately indicated by the MAC-CE if necessary.

[0192] In a second implementation for determining whether to perform an FD offset, the WTRU may determine the FD offset for the OCC based on the index of the reference PRB (e.g., the index of the first PRB) of the scheduled PDSCH transmission. If the index of the first PRB of the scheduled PDSCH transmission is an odd number, the WTRU may determine the FD offset for the OCC.

[0193] In a third specific implementation for determining the usefulness (e.g., necessity) of an FD offset, the WTRU may determine an FD offset for an OCC from an indicated set of antenna ports. A first group of antenna ports may be associated with a first OCC mapping, and a second group of antenna ports may be associated with a second OCC mapping. It should be understood that while this document refers to performing alignment by offsetting the OCC mapping, the disclosed concepts for performing alignment to prevent orphaned resources may be equally applicable to, for example, CDM groups.

[0194] An enhanced PTRS configuration may be provided. A PTRS configuration for an M-TX WTRU may be provided. For uplink transmission, the WTRU may partition the M-TX antenna set into K antenna groups, each antenna group including N TX antennas, where N≤M. It may be further assumed that the antennas within each antenna group are coherent. In order to simply present the main ideas, it is assumed that each antenna group has the same number of TX antennas, however, the same specific implementation presented below may be applicable to the case where the antenna groups have different numbers of TX antennas. A WTRU with K antenna groups may be configured with one or more DMRS ports per antenna group. The DMRS ports indicated for each antenna group may be mapped to the same CDM group.

[0195] The WTRU may be configured with more than one PTRS reference signal to assist in phase tracking at the gNB. For example, a PTRS-DMRS association may be implemented where the WTRU may indicate the number of antenna groups K, either implicitly or explicitly. Upon receiving the indication, the WTRU may be indicated one or more PTRS ports. Depending on the K antenna groups indicated, the WTRU may be indicated K or fewer PTRS ports.

[0196] For example, a PTRS-DMRS association may be implemented where the WTRU may receive an explicit indication or an implicit indication of a preferred antenna group for PTRS transmission (e.g., the antenna group with the strongest uplink transmission). The indication may be in the form of an information element indicated in a DCI or MAC CE or alternatively indicated by an SRI. The WTRU may then transmit the PTRS using the indicated antenna group.

[0197] PTRS-DMRS association may be implemented, for example, within an antenna group, where a PTRS port may be associated with the lowest indexed DMRS port associated with the antenna group.

[0198] A PTRS-DMRS association may be implemented, for example, where a WTRU with K antenna groups may cycle PTRS transmissions over the K antenna groups. The length of the cycle may be fixed or indicated by semi-static or dynamic signaling. The WTRU may be instructed to cycle the PTRS ports based on one or more of the following: as per the transmit grant, e.g., for the first transmission, antenna group X may be used and for the second transmission, antenna group Y may be used; as per the number of time slots, e.g., odd / even, every X time slots; the cycle may follow a pseudo-random sequence, where the cycle may be initialized by a seed. The seed may be explicitly indicated to the WTRU or implicitly determined based on other configuration parameters. The RB locations used for PTRS mapping may also change with each PTRS transmit cycle from the antenna groups.

[0199] An indication of a PTRS-DMRS association may be provided. In the NR uplink, the WTRU may determine the PT-RS port association with the DM-RS port based on the indication received in the DCI and based on the WTRU capabilities. Ports may be indicated, for example, up to two PT-RS ports. For a fully coherent WTRU, a single PT-RS port may be used, while a partial or non-coherent WTRU may use two PT-RS ports. In the non-codebook case, the WTRU may receive a DCI with an SRI indicating an SRS resource. The WTRU may receive an SRS configuration that indicates the PT-RS port associated with each SRS resource (ptrs-PortIndex in SRS-Config). In the codebook case, the WTRU may receive a DCI with a 2-bit field PTRS-DMRS association. When 1 PTRS port is used, this may indicate one of the four antenna ports, and the DMRS port mapped to the indicated antenna port may be associated with the PTRS port. If 2 PTRS ports are available, the MSB and LSB of the DCI field may indicate one of the antenna ports used for PTRS.

[0200] However, if a larger number of antenna ports may be considered, there may be no rules to map PT-RS ports to DMRS.

[0201] MAC-CE based PTRS-DMRS port association may be provided. One example implementation may be to increase a bit field in the DCI and dynamically indicate all (eg, all new) possible combinations resulting from the addition of DMRS ports. Fig.16An example Table 1 showing a PTRS-DMRS single port association for 8 DMRS ports is depicted. In Table 1, 3 bits may be used to define the association for up to 8 DMRS ports when a single PTRS port is used. The WTRU may receive an RRC configuration table and the DCI may indicate one of the values ​​in the table. The different tables indicating PTRS-DMRS port associations may be configured depending on the environment, for example, per serving cell, and the use of the tables may be conditional on the presence of one or more additional configurations and / or WTRU capabilities (e.g., 8TX).

[0202] The WTRU may determine the PTRS-DMRS port association based on a MAC-CE, which may indicate a PTRS-DMRS port association from a table such as Fig.16 The MAC-CE may include an explicit indication of the association between the indicated DMRS port and the PT-RS port. The WTRU may receive a MAC-CE with an indication of one of the 8 ports from the DMRS index. Fig.16 The example table depicted in provides an exemplary mapping of a value to a DMRS port association, where the value represents a numerical value equivalent to a bit string (e.g., 3 bits). The MAC CE may additionally include fields that may indicate one or more serving cells and / or cell IDs to which the association applies. If a single PTRS port can be used, the MAC-CE may include a 3-bit indication field, and the WTRU may use the 3-bit indication to determine which DMRS port to send the PTRS on. A single PTRS port may be associated with a DMRS. The WTRU may use the PTRS-DMRS port association until the WTRU receives another MAC-CE that may activate a different association. When the MAC entity receives the MAC CE, the WTRU may forward the contents of the MAC CE to lower layers for processing.

[0203] The MAC CE may indicate that the association is deactivated. Upon receiving a deactivate MAC CE, the WTRU may no longer consider the association valid and may revert to a default and / or alternative association. Whether the MAC CE activates and / or deactivates an association may be explicitly indicated via a field that may be identified, for example, by a flag bit.

[0204] The WTRU may receive a MAC-CE with 8 DMRS port indices and more than one PTRS port index. The PTRS port may be communicated via a Fig.16 The mapping depicted in Table 1 depicted in is explicitly associated with a DMRS port. When multiple DMRS ports are associated with the same PTRS port, the WTRU may receive additional rules to determine one DMRS. The rule may be based on, for example, the lowest scheduled DMRS port among all ports associated with the same DMRS port.

[0205] In one example, the MAC-CE may include an indication to map DMRS ports 1-4 to a first PTRS port and DMRS ports 5-8 to a second PTRS port. After receiving the MAC-CE, the WTRU may receive a DCI to schedule the PUSCH with 8TX. Based on the received MAC-CE activation, the WTRU may send a two-port PTRS and a UL DMRS sent on the PUSCH. The WTRU may determine to send two PTRS, where the first PTRS is associated with the lowest DMRS port in the first group (scheduling port 1), and the second PTRS port may be associated with the lowest DMRS port in the second group (scheduling port 5).

[0206] Upon receiving a DCI indication and / or MAC CE activation / deactivation, the WTRU may assume that the configuration may be valid for a certain period of time and / or amount of resources. Upon receiving a DCI and / or MAC CE activation / deactivation, the WTRU may start an inhibit timer, where the WTRU may not expect to receive updated values. The WTRU may, for example, discard any subsequent DCI values ​​and / or MAC CE activation / deactivation received during this time.

[0207] In the absence of a DCI indication and / or MAC CE activation, the WTRU may choose to apply a default value. The default value may be based on configuration information, or alternatively may be indicated via, for example, system information. Once the WTRU may have received a DCI indication value and / or an association for a MAC CE activation, the WTRU may apply the value for, for example, one or more of the following durations: for transmission and / or reception scheduled by the DCI; for a specific duration after the DCI reception and / or MAC CE activation; or until a subsequent DCI and / or MAC CE indicates a value and / or association that is different from the previously indicated value. In the case where the applied duration is a specific duration after the DCI reception and / or MAC CE activation, the WTRU may assume that the value is valid for the next X seconds and / or the next Y transmissions / receptions. Upon receipt of a DCI or MAC CE, the WTRU may start a timer or counter. Upon expiration of the counter, the WTRU may, for example, revert back to the default value and / or expect and / or request an updated value.

[0208] The WTRU may request a PTRS-DMRS port association from the network. The request may be via MAC CE, UCI or via RRC signaling and may be specific to a cell and / or PTRS port. The WTRU may transmit such a request, for example, upon one or more of the following events: upon expiration of the validity of the association (e.g., expiration of a timer and / or counter); upon RRC reconfiguration (e.g., upon reconfiguration of the PTRS-DMRS port association table); upon beam failure detection (BFD) and / or beam failure recovery (BFR); upon radio link failure (RLF); upon RRC state transition (e.g., upon transition to and / or from RRC_IDLE state, RRC_INACTIVE state, RRC_CONNECTED state).

[0209] When moving to a new cell, the WTRU may be set up with a PTRS-DMRS port association as part of the RRC reconfiguration. The WTRU may alternatively receive an indication (eg, within a handover command) that the PTRS-DMRS association is the same and / or different from the current serving cell.

[0210] The PTRS-DMRS port association may be based on the DCI and the MAC-CE. The MAC-CE may activate or indicate a PTRS-DMRS port association from a subset of all possible associations. The WTRU may dynamically select one of the indicated associations from the MAC-CE based on a field in the DCI. The WTRU may receive a PTRS-DMRS port association as described in, for example, Fig.17 The MAC-CE field may be a two-bit field configured as indicated in Table 2 depicted in FIG. Table 2 indicates a subset of configured PTRS-DMRS port associations. Table 2 may include Fig.16 After receiving the MAC-CE, the WTRU may receive a DCI scheduling the PUSCH, and the DCI may reuse the existing PTRS-DMRS association field in the DCI to signal the PTRS-DMRS association field from the WTRU. Fig.17 For example, if the WTRU may receive a PTRS-DMRS association value of 2, the WTRU may select one of the PTRS-DMRS port association fields of the subset indicated in Table 2 depicted in FIG. 1 . Fig.17 The information in Table 2 depicted in is used to determine whether to send PTRS in the same port as the 5th scheduled DMRS port.

[0211] If more than one PTRS port is available, the ports may be configured according to a table such as, for example, Fig.18The row index of Table 3 depicted in FIG. 3 associates each DMRS port set with a PTRS port. Table 3 indicates a subset of the PTRS-DMRS port associations configured for the 2-port case. If the WTRU receives a value of 2, the WTRU may determine based on the information in Table 3 that the 1st scheduled DMRS port and the 5th scheduled DMRS port may be associated with the first PTRS port and the second PTRS port, respectively.

[0212] Dynamic PTRS field re-interpretation may be performed based on the actual number of layers. The WTRU may determine that one or more codepoints of the PTRS field in the DCI (e.g., the "PTRS-DMRS Port Association" field) may be re-interpreted based on the actual number of layers that may be indicated together with the DCI (or in association with the DCI, or through a second field of the DCI (e.g., the "Precoding Information and Number of Layers" field) indicating the actual number of scheduled layers.

[0213] The WTRU may apply a predefined or preconfigured PTRS field (e.g., a "PTRS-DMRS Port Association" field) in response to determining that the actual number of layers is less than or equal to L. For a 4-Tx UL operation mode, L may be 2. For an 8-Tx UL operation mode, L may be 4. The predefined or preconfigured PTRS field may be based on the PTRS field as described in Fig.19 Table 4 (for 1PTRS port case) and Table 5 (for 2PTRS port case) depicted in. Table 4 indicates an example predefined or preconfigured PTRS-DMRS port association for the 1-port case (if the actual number of layers <= L). Table 5 indicates an example predefined or preconfigured PTRS-DMRS port association for the 2-port case (if the actual number of layers <= L).

[0214] The WTRU may apply a second re-interpreted PTRS field (e.g., "PTRS-DMRS Port Association" field) pre-configured / indicated (e.g., via RRC and / or MAC-CE) in response to determining that the actual number of layers (e.g., represented by K) is greater than L. For a 4-Tx UL mode of operation, L may be 2. For an 8-Tx UL mode of operation, L may be 4. The second re-interpreted PTRS field may be based on Fig. 20 The following Table 6 (for 1PTRS port case) and Table 7 (for 2PTRS port case) are depicted in FIG. 6. Table 6 indicates an example (second) re-interpreted PTRS-DMRS port association for the 1-port case (when the actual number of layers (K)>L). Table 7 indicates an example (second) re-interpreted PTRS-DMRS port association for the 2-port case (when the actual number of layers (K)>L).

[0215] In Table 6, the value (or code point) of the second re-interpreted PTRS field (for the 1-port case) may indicate the f(K)th scheduled DMRS port or the g(K)th scheduled DMRS port, where f(K) or g(K) may be a preconfigured / indicated function of K (as the actual number of layers). f(K) may be preconfigured or indicated as f(K)=K-1, and g(K) may be preconfigured or indicated as g(K)=K. If the WTRU may determine that the actual (scheduled) number of layers K may be 5 (>L), the WTRU may interpret the value (or code point) 2 as "the 4th scheduled DMRS port" based on f(5)=5-1=4, and may interpret the value (or code point) 3 as "the 5th scheduled DMRS port" based on f(5)=5. If the WTRU can determine that the actual (scheduled) layer number K may be 7 (>L), the WTRU may interpret the value (or code point) 2 as “the 6th scheduled DMRS port” based on f(7)=7-1=6, and interpret the value (or code point) 3 as “the 7th scheduled DMRS port” based on f(7)=7.

[0216] The WTRU may receive different functions of f(K) and g(K) (e.g., via preconfiguration or indication), which may provide benefits in terms of flexibility in allocating different PTRS-DMRS mapping patterns and improved performance based on flexible association between PTRS ports and DMRS ports.

[0217] In Table 7, the value (or code point) of the second re-interpreted PTRS field (for the 2-port case) may indicate the h(K)th DMRS port sharing PTRS port 0 or the i(K)th DMRS port sharing PTRS port 1, where h(K) or i(K) is a pre-configured / indicated function of K (as the actual number of layers). The WTRU may determine which (if any) DMRS ports are shared with PTRS port 0 or 1 based on a pre-configured higher layer message (or parameter). For example, an RRC (and / or MAC-CE) parameter may configure / indicate such an association between the DMRS ports and the PTRS ports to be shared with each other. h(K) may be pre-configured or indicated as h(K) = floor(K / 2), and i(K) may be pre-configured or indicated as i(K) = floor(K / 2). The function floor(A) may imply an integer that may exceed or may not exceed the input value A of the function. If the WTRU can determine that the actual (scheduled) number of layers K is 5 (>L), the WTRU may interpret the value 1 of the MSB as "the 2nd DMRS port sharing PTRS port 0" based on h(5) = floor(5 / 2) = 2, and interpret the value 1 of the LSB as "the 2nd DMRS port sharing PTRS port 1" based on i(5) = floor(5 / 2). If the WTRU can determine that the actual (scheduled) number of layers K is 7 (>L), the WTRU may interpret the value 1 of the MSB as "the 3rd DMRS port sharing PTRS port 0" based on h(7) = floor(7 / 2) = 3, and interpret the value 1 of the LSB as "the 3rd DMRS port sharing PTRS port 1" based on i(7) = floor(7 / 2).

[0218] The WTRU may receive h(K) and i(K) according to different pre-configured or indicated functions, which may provide benefits in terms of the flexibility of allocating different PTRS-DMRS mapping patterns and improving performance based on the flexible association between the PTRS port and the DMRS port.

[0219] The parameter of L (as the layer domain threshold) may be configured or indicated as more than one, meaning that L1, L2, etc. may be configured or indicated. For example, for the 8-Tx UL operation mode, L1 may be set to 4 and L2 may be set to 6, where the WTRU may be configured or indicated using an additional (third) re-interpreted PTRS-DMRS port association table (or field). The second re-interpreted PTRS-DMRS port association table (or field) may be applicable to L1 < K <= L2, and the third re-interpreted PTRS-DMRS port association table (or field) may be applicable to K > L2, and so on.

[0220] The WTRU may perform reporting (sending) WTRU capability parameters / information related to (e.g., based on) at least one of L, L1, L2, f(K), g(K), h(K), and i(K), etc. Based on receiving such WTRU capability report from the WTRU, the gNB may configure or instruct the WTRU on at least one of L, L1, L2, f(K), g(K), h(K), and i(K), etc. for re-interpretation behavior of PTRS-DMRS port association and determine which DMRS port(s) the PTRS port is mapped to.

[0221] The WTRU may be configured to associate a DMRS port group with a code division multiplexing (CDM) group and map the DMRS port group associated with the CDM group to a group of antenna groups. The WTRU may be configured to determine the mapping of the PTRS port to the DMRS port based on the MCS value associated with the DMRS port.

[0222] Fig.21 Depicted are example implementations for antenna groups and PTRS-DMRS determination, where each CDM / DMRS group may be mapped to a different antenna group. Fig. 22 Depicted is an example CDM / DMRS mapping to antenna groups for 8-layer transmission. Fig. 22 In the example depicted in , CDM to antenna group mapping may be depicted for 8 layers of transmission, where each CDM group may have a length of 4.

[0223] refer to Fig.21 The example implementation depicted in Fig.21 A WTRU, which may be referred to as a UE in the specification, may, for example, implicitly or explicitly report (e.g., indicate) information about its coherent capabilities and antenna layout. The indicated information may include, for example, the number of antenna groups Ng. As shown, the information may indicate, for example, one coherent antenna group of 8 transmitters (Ng=1) or two coherent transmitter groups of 4 (Ng=2). Based on the indicated antenna grouping, a network device such as, for example, a base station (e.g., a gNB for the examples herein) may schedule uplink transmissions and transmit scheduling DCI to the WTRU, such as information scheduling PUSCH transmissions and information about DMRS antenna ports and one or more PTRS ports.

[0224] The WTRU may receive a DCI that schedules a transmission (eg, a PUSCH transmission) and / or may include association information that associates a DMRS port with a CDM group. The DCI may include information about a DMRS antenna port and one or more PTRS ports.

[0225] The WTRU may relate or associate a first set of DMRS ports with a first CDM group and relate or associate a second set of DMRS ports with a second CDM group based on association information indicated in the DCI.

[0226] The WTRU may map a first set of DMRS ports associated with a first CDM group to a first antenna group and may map a second set of DMRS ports associated with a second CDM group to a second antenna group. If the WTRU includes one coherent antenna group, e.g., Ng=1, the WTRU may map each determined CDM group (and associated DMRS group) to the one antenna group. A WTRU configured with more than one CDM group may map the DMRS ports for each antenna group to the same CDM group.

[0227] The WTRU may send a scheduled transmission, which may be, for example, a PUSCH transmission. The transmission may include at least a first DMRS that may be sent using a first set of DMRS ports and a first antenna group and at least a second DMRS that may be sent using a second set of DMRS ports and a second antenna group.

[0228] The received DCI may indicate one or more PTRS ports. If one PTRS port is configured or indicated, the WTRU may map the one PTRS port to a first DMRS port in the first set or the second set of DMRS ports. The first DMRS port may be determined based on an MCS associated with the first DMRS port, and the one PTRS port may be used to transmit the PTRS based on the mapping to the first DMRS port. The DMRS port with the strongest link for uplink transmission may be used for PTRS transmission, which DMRS port may be determined based on the associated MCS (e.g., the highest MCS value in the MCS value associated with the first set or the second set of DMRS ports).

[0229] If more than one PTRS port is configured or indicated, the WTRU may map a first PTRS port to a first DMRS port that may be mapped to a first antenna group, and may map a second PTRS port to a second DMRS port that may be mapped to a second antenna group. For example, along with PUSCH transmission and DMRS, the WTRU may transmit at least a first PTRS using the first PTRS port based on the mapping to the first DMRS port, and may transmit at least a second PTRS using the second PTRS port based on the mapping to the second DMRS port.

[0230] Although the features and elements described herein are described in particular combinations, each feature or element may be used alone without the other features and elements of the preferred embodiments, or in various combinations with or without the other features and elements.

[0231] The description herein is provided for exemplary purposes and does not in any way limit the applicability of the described systems, methods, and apparatuses to other wireless technologies and / or wireless technologies using different principles where applicable. The term network in the present disclosure may refer to one or more gNBs (which in turn may be associated with one or more transmit / receive points (TRPs)), or may refer to any other node in a radio access network.

[0232] Although the implementations described herein may consider 3GPP specific protocols, it should be understood that the implementations described herein are not limited to such scenarios and are applicable to other wireless systems. For example, although the solutions described herein consider LTE, LTE-A, New Radio (NR) or 5G specific protocols, it should be understood that the solutions described herein are not limited to such scenarios and are also applicable to other wireless systems.

[0233] The processes described herein may be implemented in a computer program, software, and / or firmware incorporated in a computer-readable medium for execution by a computer and / or processor. Examples of computer-readable media include, but are not limited to, electronic signals (sent via wired and / or wireless connections) and / or computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as, but not limited to, built-in hard disks and removable disks), magneto-optical media, and / or optical media (such as compact disk (CD)-ROM disks and / or digital versatile disks (DVDs)). A processor associated with the software may be used to implement a radio frequency transceiver for a WTRU, a terminal, a base station, an RNC, and / or any host computer.

Claims

1. A wireless transmit and receive unit (WTRU), comprising: A processor, the processor being configured to: receiving downlink control information (DCI) including information scheduling a transmission and associating a demodulation reference signal (DMRS) port with a code division multiplexing (CDM) group; associating first one or more DMRS ports with a first CDM group based on the DCI; associating a second one or more DMRS ports with a second CDM group based on the DCI; mapping the first one or more DMRS ports associated with the first CDM group to a first antenna group; mapping the second one or more DMRS ports associated with the second CDM group to a second antenna group; as well as The transmission is transmitted, the transmission comprising at least a first DMRS transmitted using the first one or more DMRS ports and the first antenna group and at least a second DMRS transmitted using the second one or more DMRS ports and the second antenna group.

2. The WTRU of claim 1 , wherein the processor is further configured to: Information associated with at least one of coherence capability or antenna layout is transmitted.

3. The WTRU of claim 2, wherein the information associated with the at least one of coherence capability or antenna layout comprises information identifying one or more coherent antenna groups.

4. The WTRU of claim 3, wherein the information identifying one or more coherent antenna groups comprises information identifying a number of antenna groups.

5. The WTRU of claim 3, wherein the information that schedules the transmissions and associates DMRS ports with CDM groups is based on the information that identifies one or more coherent antenna groups.

6. The WTRU of claim 1, wherein the processor configured to receive DCI is configured to receive the DCI from a base station.

7. The WTRU of claim 1 , The processor is further configured to: determining a first DMRS port from the first one or more DMRS ports or the second one or more DMRS ports based on a modulation and coding scheme (MCS) value associated with the first DMRS port; and associating a first phase tracking radio signal (PTRS) port with the first DMRS port; and The sending further comprises transmitting the PTRS using the first PTRS port.

8. A WTRU according to claim 7, wherein the processor configured to determine the first DMRS port based on the MCS value is further configured to: determine the first DMRS port based on the MCS value which is the highest MCS value associated with the first one or more DMRS ports or the second one or more DMRS ports.

9. The WTRU of claim 7, wherein the DCI includes information indicating the first PTRS port.

10. The WTRU of claim 3, wherein the processor is further configured to: Associating a first PTRS port with a first DMRS port mapped to the first antenna group; and associating a second PTRS port with a second DMRS port mapped to the second antenna group; and The sending further includes a first PTRS transmitted using the first PTRS port and a second PTRS transmitted using the second PTRS port.

11. The WTRU of claim 10, wherein the DCI includes information indicating a plurality of PTRS ports.

12. The WTRU of claim 1, wherein the transmission further comprises a physical uplink shared channel (PUSCH) transmission.

13. A port mapping method, comprising: receiving downlink control information (DCI) including information scheduling a transmission and associating a demodulation reference signal (DMRS) port with a code division multiplexing (CDM) group; associating first one or more DMRS ports with a first CDM group based on the DCI; associating a second one or more DMRS ports with a second CDM group based on the DCI; mapping the first one or more DMRS ports associated with the first CDM group to a first antenna group; mapping the second one or more DMRS ports associated with the second CDM group to a second antenna group; as well as The transmission is transmitted, the transmission comprising at least a first DMRS transmitted using the first one or more DMRS ports and the first antenna group and at least a second DMRS transmitted using the second one or more DMRS ports and the second antenna group.

14. The method according to claim 13, further comprising: Information associated with at least one of coherence capability or antenna layout is transmitted.

15. The method of claim 14, wherein the information associated with the at least one of coherence capabilities or antenna layout comprises information identifying one or more coherence antenna groups.

16. The method of claim 15, wherein the information identifying one or more coherent antenna groups comprises information identifying a number of antenna groups.

17. The method of claim 15, wherein the information that schedules the transmissions and associates DMRS ports with CDM groups is based on the information identifying one or more coherent antenna groups.

18. The method of claim 13, wherein receiving the DCI comprises: Receive DCI from a base station.

19. The method according to claim 13, further comprising: determining a first DMRS port from the first one or more DMRS ports or the second one or more DMRS ports based on a modulation and coding scheme (MCS) value associated with the first DMRS port; as well as associating a first phase tracking radio signal (PTRS) port with the first DMRS port; and The sending further comprises transmitting the PTRS using the first PTRS port.

20. The method of claim 19, wherein determining the first DMRS port based on the MCS value comprises: The first DMRS port is determined based on the MCS value being a highest MCS value associated with the first one or more DMRS ports or the second one or more DMRS ports.

21. The method of claim 19, wherein the DCI includes information indicating the first PTRS port.

22. The method of claim 15, further comprising: Associating a first PTRS port with a first DMRS port mapped to the first antenna group; as well as Associating a second PTRS port with a second DMRS port mapped to the second antenna group; The sending further includes a first PTRS transmitted using the first PTRS port and a second PTRS transmitted using the second PTRS port.

23. The method of claim 22, wherein the DCI includes information indicating a plurality of PTRS ports.

24. The method of claim 13, wherein the transmitting further comprises a physical uplink shared channel (PUSCH) transmission.

25. A computing system comprising: A processor, the processor being configured to: receiving information associated with at least one coherence capability or antenna layout from a wireless transmit and receive unit (WTRU); determining information for scheduling transmissions and associating DMRS ports with CDM groups based on the information associated with at least one coherence capability or antenna layout; as well as The information scheduling the transmission and associating a DMRS port with a CDM group is transmitted to the WTRU.

26. The computing system of claim 25, Wherein the information associated with the at least one of coherence capability or antenna layout includes information identifying one or more coherence antenna groups.

27. The computing system of claim 26, The information identifying one or more coherent antenna groups includes information identifying the number of antenna groups.

28. The computing system of claim 25, The information scheduling the transmission and associating DMRS ports with CDM groups comprises downlink control information (DCI).

29. The computing system of claim 25, Wherein the transmission is a physical uplink shared channel (PUSCH) transmission.

30. The computing system of claim 25, wherein the computing system is a base station.

31. A method comprising: receiving information associated with at least one coherence capability or antenna layout from a wireless transmit and receive unit (WTRU); determining information for scheduling transmissions and associating DMRS ports with CDM groups based on the information associated with at least one coherence capability or antenna layout; as well as The information scheduling the transmission and associating a DMRS port with a CDM group is transmitted to the WTRU.

32. The method according to claim 31, Wherein the information associated with the at least one of coherence capability or antenna layout includes information identifying one or more coherence antenna groups.

33. The method according to claim 32, The information identifying one or more coherent antenna groups includes information identifying the number of antenna groups.

34. The method according to claim 31, The information scheduling the transmission and associating DMRS ports with CDM groups comprises downlink control information (DCI).

35. The method according to claim 31, Wherein the transmission is a physical uplink shared channel (PUSCH) transmission.

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