Insertion of distributed reference signals in DFT-s-OFDM

Abstract

Some implementations provide devices, methods, and systems for receiving data by extending an Orthogonal Frequency Division Multiplexing (DFT-s-OFDM) waveform through a Discrete Fourier Transform. A reference signal (RS) configuration message is received. A fill sequence structure is determined based on the received indication. And the DFT-s-OFDM symbol is received. Interference is eliminated based on the filling sequence structure. In some implementations, the padding sequence structure includes a constant envelope sequence, symbol-inverted data symbols, phase-shifted data symbols, and / or blank symbols. In some implementations, the RS configuration message includes an RS sequence, an RS length, and / or a subcarrier offset.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 331,031, filed on April 14, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] Discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) is a single-carrier waveform (e.g., as adopted by the 3rd Generation Partnership Project (3GPP) for the uplink of 4G Long Term Evolution (LTE) and 5G New Radio (NR) wireless cellular standards).

[0004] Unlike other multi-carrier waveforms like cyclic prefix-orthogonal frequency division multiplexing (CP-OFDM), the single-carrier nature of DFT-s-OFDM can allow for a reduced peak-to-average power ratio (PAPR) while retaining other benefits of CP-OFDM, such as DFT-based frequency domain equalization and simple inter-symbol interference (ISI) suppression. The efficiency of the power amplifier (PA) can be improved with the reduced PAPR because the output power range over which the device maintains a linear response can be larger, thereby delivering higher output power for the same PA technology. This property can be particularly relevant when the carrier frequency increases beyond frequency range 2 (FR2) (i.e., above 52.6 GHz) because PA efficiency begins to decrease significantly at these higher frequencies.

[0005] DFT-s-OFDM can be basically characterized by a transform pre-coding stage added to the normal processing steps in CP-OFDM. In some implementations, transform pre-coding can only achieve a single carrier waveform in the time domain if the subcarriers are mapped to continuous frequency positions, which can limit the flexibility of DFT-s-OFDM in allocating control information and data information in the frequency domain. In some implementations, for this reason, in some implementations, control channels and data channels in 5G NR are not multiplexed in frequency, but are assigned different DFT-s-OFDM symbols so that the single carrier property is preserved. This can also apply to some 5G NR reference signals (RS), such as DM-RS, which do not allow data information to be multiplexed in the same symbol. Summary of the invention

[0006] Some specific implementations provide a method for receiving data via a DFT-s-OFDM waveform. Receive an RS configuration message. Determine a filling sequence structure based on the received indication. Receive a DFT-s-OFDM symbol. Eliminate interference based on the filling sequence structure. In some specific implementations, the filling sequence structure includes a constant envelope sequence, a symbol-reversed data symbol, a phase-shifted data symbol, and / or a blank symbol. In some specific implementations, the RS configuration message includes an RS sequence, an RS length, and / or a subcarrier offset. In some specific implementations, the RS configuration message is received in a DCI, a MAC CE, and / or an RRC message. In some specific implementations, the received indication includes a filling sequence structure identifier and / or a codebook index. In some specific implementations, the received indication is received in a DCI, a MAC CE, and / or an RRC message. In some specific implementations, the filling sequence structure is estimated by blind detection based on the received indication. In some specific implementations, eliminating the interference includes eliminating interference from the DFT-s-OFDM symbol based on the filling sequence structure. In some implementations, eliminating the interference based on the filling sequence structure includes eliminating interference caused by inserting the RS into the DFT-s-OFDM symbol. In some implementations, eliminating the interference based on the filling sequence structure includes eliminating the interference from the DFT-s-OFDM symbol before demodulation. Some implementations also include sending feedback based on the elimination of the interference. The feedback includes an indication of the performance of the elimination of the interference, an indication of a preferred filling sequence structure, an indication of a BER, and / or an indication of a BLER.

[0007] Some specific implementations provide a WTRU configured to receive data via a DFT-s-OFDM waveform. The WTRU includes a circuit configured to receive an RS configuration message. The WTRU also includes a circuit configured to determine a fill sequence structure based on the received indication. The WTRU also includes a circuit configured to receive a DFT-s-OFDM symbol. The WTRU also includes a circuit configured to eliminate interference based on the fill sequence structure. In some specific implementations, the fill sequence structure includes at least one of the following: a constant envelope sequence, a symbol-reversed data symbol, a phase-shifted data symbol, or a blank symbol. In some specific implementations, the RS configuration message includes at least one of the following: an RS sequence, an RS length, or a subcarrier offset. Some specific implementations also include a circuit configured to receive the RS configuration message in a DCI, a MAC CE, and / or an RRC message. In some specific implementations, the received indication includes a fill sequence structure identifier or a codebook index. Some specific implementations also include a circuit configured to receive the indication in a DCI, a MAC CE, and / or an RRC message. Some specific implementations also include a circuit configured to estimate the filling sequence structure by blind detection based on the received indication. Some specific implementations also include a circuit configured to eliminate the interference from the DFT-s-OFDM symbol based on the filling sequence structure. Some specific implementations also include a circuit configured to eliminate the interference caused by inserting the RS into the DFT-s-OFDM symbol. Some specific implementations also include a circuit configured to eliminate the interference from the DFT-s-OFDM symbol before demodulation. Some specific implementations also include a circuit configured to send feedback based on the elimination of the interference. The feedback includes an indication of the performance of the elimination of the interference, an indication of a preferred filling sequence structure, an indication of the BER and / or an indication of the BLER.

[0008] Some specific implementations provide devices, methods, and systems for post-DFT RS insertion based on padding sequence adaptation. Information about the characteristics of the inserted RS, such as the RS sequence to be used, its length, or the first subcarrier offset, is received in an RS configuration message. A measurement (e.g., PAPR) is performed on one or more generated signals, wherein the generated signal is a time domain signal, the time domain signal including a signal addressed to a second WTRU or a set of second WTRUs. The measurement result (e.g., PAPR) is compared with a first threshold. One or more padding sequence structures are updated from a padding sequence structure codebook based on the PAPR measurement result. Signaling information (e.g., on the padding sequence structure used) is transmitted to the second WTRU or a set of second WTRUs. A first set of symbols is constructed by appending one or more padding sequences to a second set of complex modulated data symbols in a DFT-s-OFDM symbol. A DFT operation is performed on the first set of symbols to determine a discrete frequency response on a first set of subcarriers. A subset of the subcarriers is punctured, and complex RS symbols are inserted in the frequency domain at the locations of the punctured subcarriers to obtain a second set of subcarriers. IFFT is performed on the second subcarrier set, and a DFT-s-OFDM symbol including data and RS is transmitted.

[0009] Some specific implementations provide devices, methods, and systems for post-DFT RS insertion based on padding sequence adaptation. Information about the characteristics of the inserted RS is received in an RS configuration message, such as the RS sequence to be used, its length, or the first subcarrier offset. Feedback information is received from the second WTRU, such as a time domain report message and decoding performance (e.g., BLER). Measurements (e.g., PAPR) are performed on one or more generated signals, and the measurements are compared with a first threshold, wherein the generated signals are time domain signals, and the time domain signals include signals addressed to the second WTRU or a set of second WTRUs. The time domain report message (e.g., maximum autocorrelation) is compared with a second threshold. The decoding performance (e.g., BLER) is compared with a third threshold. Based on the PAPR measurement result or the feedback information being higher than the first threshold or the second threshold, one or more padding sequence structures are selected from a subset of the padding sequence structure codebook characterized by a lower PAPR. Based on the decoding performance being higher than the third threshold, one or more padding sequence structures are selected from a subset of the padding sequence structure codebook characterized by a lower BLER. Signaling information (e.g., on the padding sequence structure used) is transmitted to the second WTRU or set of second WTRUs. A first set of symbols is constructed by appending one or more padding sequences to a second set of complex modulated data symbols in a DFT-s-OFDM symbol. A DFT operation is performed on the first set of symbols to determine a discrete frequency response on a first set of subcarriers. A subset of the subcarriers is punctured, and complex RS symbols are inserted in the frequency domain at the locations of the punctured subcarriers to obtain a second set of subcarriers. An IFFT is performed on the second set of subcarriers, and a DFT-s-OFDM symbol including data and RS is transmitted.

[0010] Some implementations provide apparatus, methods, and systems for post-DFT RS insertion with padding sequence adaptation. Information about characteristics of the inserted RS is received in an RS configuration message, such as an RS sequence to be used, its length, or a first subcarrier offset. A padding sequence structure indication is determined from a codebook based on the received indication, such as by DCI in a PDCCH message. A DFT-s-OFDM symbol including data and RS is received. Interference from subcarrier puncturing and RS insertion is eliminated based on the determined padding sequence structure.

[0011] Some specific implementations provide devices, methods and systems for post-DFT RS insertion with padding sequence adaptation. Information about the characteristics of the inserted RS is received in an RS configuration message, such as the RS sequence to be used, its length or the first subcarrier offset. A padding sequence structure indication is determined from a codebook based on the received indication, for example, by DCI in a PDCCH message. A DFT-s-OFDM symbol including data and RS is received, and a quality indication is determined. Interference caused by RS insertion is eliminated based on the determined padding sequence structure. The quality indication is compared with a first threshold. A time domain measurement of the maximum autocorrelation of the received signal is performed based on the quality indication being above the first threshold. A time domain measurement of the absolute magnitude of interference on the received signal is performed based on the quality indication being below the first threshold. Decoding performance (e.g., BLER) is detected. A codebook subset with a lower PAPR is selected based on the maximum autocorrelation being above a second threshold or the interference being above a third threshold. A codebook subset with a lower BLER is selected based on the decoding performance being above a fourth threshold. Feedback information (e.g., a time domain report message or a padding sequence structure report) is sent.

[0012] Some specific implementations provide devices, methods and systems for IFDMA-based pre-DFT RS insertion. Information about the characteristics of the inserted RS is received in an RS configuration message, which may include the RS sequence to be used, its length or a first subcarrier offset. A first set of complex pilot symbols is determined by performing one or more repetitions of the RS sequence. A first set of complex data symbol groups is generated by dividing the complex modulated data symbols into one or more consecutive symbol groups. A second set of complex data symbol groups is generated by performing one or more repetitions of each group of symbols in the first set of complex data symbol groups. A second set of complex pilot symbols is generated by applying a first subcarrier offset to the first set of complex pilot symbols. A third set of complex data symbol groups is generated by applying a second subcarrier offset set to the second set of complex data symbol groups. A DFT operation is performed on the sum of the second set of complex pilot symbols and the third set of complex data symbol groups to determine a discrete frequency response on a set of subcarriers. An IFFT is performed on the set of subcarriers, and a DFT-s-OFDM symbol including data and RS is sent. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate like elements, and in which:

[0014] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0015] Figure 1Bis an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within the illustrated communication system;

[0016] Figure 1C is an example of an embodiment in which Figure 1A a system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0017] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0018] Figure 2 is a diagram illustrating example pre-DFT and post-DFT insertion of RS in DFT-s-OFDM;

[0019] Figure 3 is a diagram illustrating an example method for post-DFT insertion using subcarrier interleaving;

[0020] Figure 4 is a diagram illustrating an example RS insertion achieved by subcarrier puncturing through zero padding;

[0021] Figure 5 is a flow chart illustrating a high-level process.

[0022] Figure 6 is a flow chart illustrating a process in which a transmitting node inserts a pre-DFT RS based on interleaved frequency division multiple access (IFDMA) multiplexing of RS and data;

[0023] Figure 7 is a flow chart illustrating more detailed processing steps for pre-DFT RS insertion of a pre-DFT RS implemented by a transmitting node based on IFDMA;

[0024] Figure 8 is a diagram illustrating an example multiplexing of RS and data in pre-DFT insertion based on IFDMA;

[0025] Fig. 9 is a flow chart illustrating data detection performed by a receiving node in IFDMA-based pre-DFT RS insertion;

[0026] Fig.10 is an example of Fig. 9 A flowchart of further details;

[0027] Fig.11 is a flow chart illustrating dynamic RS insertion at the BS side;

[0028] Fig.12 is an example and about Fig.11 The process shown and described corresponds to a flowchart of the processing on the BS side.

[0029] Fig.13 is a diagram illustrating sequence filling and permutation;

[0030] Fig.14 is a flow chart illustrating the details of DFT, subcarrier puncturing and RS insertion;

[0031] Fig.15 is a flow chart illustrating details of further steps for generating a DFT-s-OFDM time domain waveform;

[0032] Fig.16 is a diagram further illustrating a feedback loop between a BS and a WTRU;

[0033] Fig.17 is a flow chart illustrating an example semi-static RS insertion at the BS side;

[0034] Fig.18 is a flow chart illustrating example data detection and cancellation of interference from RS insertion at the WTRU side;

[0035] Fig.19 is a block diagram illustrating steps of receiving a DFT-s-OFDM symbol;

[0036] Fig. 20 is a flow chart illustrating dynamic RS insertion at the WTRU side;

[0037] Fig.21 is a feedback loop illustrating the described signaling interaction between the UE and the BS and the transfer of uplink data from the UE to the BS;

[0038] Fig. 22 is a line graph illustrating the PAPR for 1 DM-RS symbol;

[0039] Fig.23 is a line graph illustrating the PAPR for 4 DM-RS symbols;

[0040] Fig.24 is a line graph illustrating the BER of one DM-RS symbol under AWGN conditions;

[0041] Fig.25 is a line graph illustrating the BER of 4 DM-RS symbols under AWGN conditions;

[0042] Fig.26 is a line graph illustrating the BER of one DM-RS symbol under Rayleigh conditions;

[0043] Fig. 27 is a line graph illustrating the BER of 4 DM-RS symbols under Rayleigh conditions;

[0044] Fig.28 is a flow chart illustrating an example implementation related to detection of shared DFT-s-OFDM symbols with pre-DFT insertion of IFDMA-based RS;

[0045] Fig.29 is a flow chart illustrating an example implementation related to transmission of a shared DFT-s-OFDM symbol with post-DFT insertion of RS based on padding sequence adaptation without feedback;

[0046] Fig.30 is a flow chart illustrating an example implementation related to transmission of a shared DFT-s-OFDM symbol with post-DFT insertion of RS based on padding sequence adaptation with feedback;

[0047] Fig.31 is a flow chart illustrating an example implementation related to detection of a shared DFT-s-OFDM symbol with post-DFT insertion of RS based on padding sequence adaptation without feedback;

[0048] Fig.32 is a flow chart illustrating an example implementation related to detection of shared DFT-s-OFDM symbols with post-DFT insertion of RS based on padding sequence adaptation with feedback; and

[0049] Fig.33 is a flow chart illustrating a simplified process for detection of shared DFT-s-OFDM symbols with post-DFT insertion of RS based on padding sequence adaptation with feedback. DETAILED DESCRIPTION

[0050] 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 spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0051] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a station (STA)) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), 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.

[0052] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a next generation Node B such as a gNode B (gNB), a new radio (NR) Node B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0053] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), 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 a cell (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.

[0054] 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).

[0055] 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 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), that may use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA may include communication protocols, such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​Uplink (UL) Packet Access (HSUPA).

[0056] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-APro).

[0057] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology (such as NR radio access) that may establish the air interface 116 using NR.

[0058] 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).

[0059] 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.

[0060] 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, the base station 114 b may have a direct connection to the Internet 110. Therefore, the base station 114 b may not need to access the Internet 110 via the CN 106.

[0061] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the accompanying drawings, the CN 106 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0062] The CN 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0063] 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.

[0064] 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.

[0065] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), 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.

[0066] 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.

[0067] Although the transmit / receive element 122 Figure 1B 1 as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0068] 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.

[0069] The processor 118 of the WTRU 102 may be coupled to 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) and may receive user input data therefrom. 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).

[0070] 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.

[0071] 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.

[0072] 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, FM radio unit, digital music player, media player, video game player module, Internet browser, virtual reality and / or augmented reality (VR / AR) device, activity tracker, etc. The peripheral device 138 may include one or more sensors. The sensor may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, etc.

[0073] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous.

[0074] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0075] 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.

[0076] 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 UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0077] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0078] 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.

[0079] 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 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] In a representative embodiment, the other network 112 may be a WLAN.

[0084] 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. Services originating from outside the BSS and directed to the STA may be reached by the AP and may be delivered to the STA. Services originating from the STA and directed to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Services between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit services to the AP, and the AP may deliver services to the destination STA. Services between STAs within the BSS may be considered and / or referred to as point-to-point services. Point-to-point services may be transmitted between the source STA and the destination STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0085] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may 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.

[0086] 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.

[0087] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be sent by the transmitter STA. At the receiver of the receiver STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0088] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0089] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (which only supports a 1MHz operating mode) is transmitting to the AP, all available bands may be considered busy even if most of the available bands remain idle.

[0090] 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.

[0091] Figure 1D1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0092] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0093] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with a set of parameters 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 varying numbers of OFDM symbols and / or varying absolute time lengths over time).

[0094] 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 an unlicensed band. In a non-standalone configuration, the WTRU 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN (such as the evolved Node-B 160a, 160b, 160c). For example, the WTRU 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more evolved Node-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the evolved Node-B 160a, 160b, 160c may act as a mobility anchor for the WTRU 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRU 102a, 102b, 102c.

[0095] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, interworking between DC, NR, and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, 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.

[0096] Figure 1DThe CN 106 shown may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0097] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0098] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure 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 implementation and QoS, providing DL data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0099] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, etc.

[0100] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the local DNs 185a, 185b.

[0101] 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 items may be performed by one or more simulation devices (not shown): WTRU102a to 102d, base station 114a to 114b, evolved Node B 160a to 160c, MME 162, SGW 164, PGW 166, gNB180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0102] 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 the purpose of testing and / or performing tests using over-the-air wireless communications.

[0103] 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.

[0104] In this document, the following abbreviations and acronyms are used, inter alia:

[0105] 3GPP Third Generation Partnership Project

[0106] 4G Fourth Generation

[0107] 5G Fifth Generation

[0108] 16QAM 16-Quadrature Amplitude Modulation

[0109] 64QAM 64-Quadrature Amplitude Modulation

[0110] AWGN Additive White Gaussian Noise

[0111] BER Bit Error Rate

[0112] BLER Block Error Rate

[0113] BS Base Station

[0114] CCDF Complementary Cumulative Distribution Function

[0115] CP Cyclic Prefix

[0116] CP-OFDM Cyclic Prefix-Orthogonal Frequency Division Multiplexing

[0117] DCI Downlink Control Indicator

[0118] DFT Discrete Fourier Transform

[0119] DFT-s-OFDM Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing

[0120] DL Downlink

[0121] DM-RS Demodulation Reference Signal

[0122] Eb / N0 Ratio of bit energy to noise spectral density

[0123] FEC Forward Error Correction

[0124] FFT Fast Fourier Transform

[0125] FR2 Frequency Range 2

[0126] IDFT Inverse Discrete Fourier Transform

[0127] IFDMA Interleaved Frequency Division Multiple Access

[0128] IFFT Inverse Fast Fourier Transform

[0129] ISI Inter-Symbol Interference

[0130] LMMSE Linear Minimum Mean Square Error

[0131] LTE Long Term Evolution

[0132] MAC CE Medium Access Control Element

[0133] MIMO Multiple Input Multiple Output

[0134] ML Machine Learning

[0135] MSE Mean Square Error

[0136] ML Maximum Likelihood

[0137] MU-MIMO Multi-User Multiple Input Multiple Output

[0138] NLOS Non Line of Sight

[0139] NR New Radio

[0140] OFDM Orthogonal Frequency Division Multiplexing

[0141] PA Power Amplifier

[0142] P / S Parallel to Serial

[0143] PAPR Peak to Average Power Ratio

[0144] PDCCH Physical Downlink Control Channel

[0145] PSeqS Filled Sequence Structure

[0146] PSeqS ID Populate sequence structure identifier

[0147] PT-RS Phase Tracking Reference Signal

[0148] PUCCH Physical Uplink Control Channel

[0149] PUSCH Physical Uplink Shared Channel

[0150] QPSK Quadrature Phase Shift Keying

[0151] RRC Radio Resource Control

[0152] RNTI Radio Network Temporary Identifier

[0153] RS reference signal

[0154] SIC Successive Interference Cancellation

[0155] S / P Serial to Parallel

[0156] SNR Signal to Noise Ratio

[0157] SU-MIMO Single User Multiple Input Multiple Output

[0158] TDL Tapped Delay Line

[0159] TRP Transmit Receive Point

[0160] UCI Uplink Control Indicator

[0161] UE User Equipment

[0162] UL Uplink

[0163] WTRU Wireless Transmit / Receive Unit

[0164] Discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) is a single-carrier waveform (e.g., as adopted by the 3rd Generation Partnership Project (3GPP) for the uplink of 4G Long Term Evolution (LTE) and 5G New Radio (NR) wireless cellular standards).

[0165] Unlike other multi-carrier waveforms like cyclic prefix-orthogonal frequency division multiplexing (CP-OFDM), the single-carrier nature of DFT-s-OFDM can allow for a reduced peak-to-average power ratio (PAPR) while retaining other benefits of CP-OFDM, such as DFT-based frequency domain equalization and simple inter-symbol interference (ISI) suppression. The efficiency of the power amplifier (PA) can be improved with the reduced PAPR because the output power range over which the device maintains a linear response can be larger, thereby delivering higher output power for the same PA technology. This property can be particularly relevant when the carrier frequency increases beyond frequency range 2 (FR2) (i.e., above 52.6 GHz) because PA efficiency begins to decrease significantly at these higher frequencies.

[0166] DFT-s-OFDM can be basically characterized by a transform pre-coding stage added to the normal processing steps in CP-OFDM. In some implementations, transform pre-coding can only achieve a single carrier waveform in the time domain if the subcarriers are mapped to continuous frequency positions, which can limit the flexibility of DFT-s-OFDM in allocating control information and data information in the frequency domain. In some implementations, for this reason, in some implementations, control channels and data channels in 5G NR are not multiplexed in frequency, but are assigned different DFT-s-OFDM symbols so that the single carrier property is preserved. This can also apply to some 5G NR reference signals (RS), such as DM-RS, which do not allow data information to be multiplexed in the same symbol.

[0167] In some implementations, prior art insertion of RS in DFT-s-OFDM can be classified into either of two mechanisms: pre-DFT or post-DFT. In some implementations, RS insertion in 5G NR belongs to the pre-DFT category.

[0168] Figure 2 is a diagram illustrating an example pre-DFT insertion 200 of an RS 202 in DFT-s-OFDM and post-DFT insertion 250 of an RS 252 in DFT-s-OFDM.

[0169] Pre-DFT insertion 200 includes at least one RS 202 inserted into data 204 before applying DFT 206. In pre-DFT insertion 200, RS symbols 202 are inserted into data 204 before DFT 206 in 5G NR.

[0170] In some implementations, when inserted before the DFT, the RS symbols 202 are multiplexed with the data 204 in the time domain or mapped solely in the data 204 symbols (i.e., not multiplexed with any other data symbols) before transform pre-decoding (i.e., before the DFT 206, e.g., as described in the 5G NR standard), subcarrier mapping 208, inverse DFT (IDFT) 210, and parallel / serial conversion (P / S) 212.

[0171] In some implementations, subcarriers are mapped to consecutive frequency locations to maintain the single carrier nature of the waveform, and frequency multiplexing of control information and data information is not possible.

[0172] In some implementations, the 5G NR demodulation reference signal (DM-RS) may be mapped alone in the symbol (i.e., not multiplexed with any other data symbols) and may occupy up to four full symbols per slot in DFT-s-OFDM. In some implementations, data information is not frequency multiplexed in those symbols, which may lead to inefficiencies, for example, due to high resource utilization of control signals, for example, when more than one DM-RS symbol is used per slot. In some implementations, for example, at frequencies above 52.6 GHz, it may be necessary to increase the number of DM-RS symbols to more than one, for example, to effectively track Doppler variations at higher modulations. In some implementations, the overhead from the DM-RS may be quite high in this case.

[0173] In some implementations, the 5G NR phase tracking reference signal (PT-RS) can be multiplexed with data in the time domain before DFT. In some implementations, unlike DM-RS, PT-RS symbols are multiplexed with data before DFT, and resource utilization can be adjusted as needed. However, in some implementations, the DFT operation spreads both data and PT-RS on the output subcarriers, which may make it impossible to multiplex data and control information in the frequency domain.

[0174] In some implementations, pre-DFT RS insertion in 5G NR may therefore be limited to generating continuous RS in the frequency domain (e.g., with poor resource utilization) or RS multiplexed with data in the time domain (e.g., cannot be interleaved with data in the frequency domain).

[0175] Therefore, some implementations involve post-DFT insertion of reference signals in DFT-s-OFDM.

[0176] In post-DFT insertion 250 , at least one RS 252 is inserted into data 254 after DFT 256 is applied.

[0177] In some implementations, when inserted after DFT, RS symbols 252 are inserted after DFT 256 and before subcarrier mapping 258 , IDFT 260 , and PS 262 .

[0178] When inserted after DFT, in some implementations, RS symbols can be multiplexed with data at any frequency position required. In some implementations, the continuous allocation of data subcarriers in the frequency domain is no longer retained, and the PAPR will increase compared to the case without RS insertion, but by allocating only the required RS symbols, resource efficiency can be higher than in pre-DFT insertion.

[0179] Some implementations include interleaved RS insertion and subcarrier puncturing techniques for post-DFT insertion. For example, some implementations involve interleaved RS insertion. Figure 3 is a diagram illustrating an example post-DFT insertion 300 using subcarrier interleaving.

[0180] In this example, L reference symbols 302 are inserted into blocks of M consecutive subcarriers in a distributed manner and multiplexed with (M-L) modulated data symbols. (M-L) point DFT 306 is performed on data 304 (before IDFT 310 and P / S 312), and its output may be mapped to non-contiguous frequency locations in subcarrier mapping 308, leaving room for further allocation of L reference symbols in an interleaved form. In some embodiments, L reference symbols 302 and (M-L) data symbols 304 are effectively interleaved across M subcarriers in this manner.

[0181] In some implementations, the process may be adapted to insert distributed RS at non-periodic positions in the frequency domain. However, in some implementations, this may have the disadvantage of forcing the transceiver to use different DFT sizes for DFT-s-OFDM symbols carrying RS (ML) and those not carrying RS (M), thus complicating the implementation. Furthermore, in some implementations, both (ML) and M must conform to the DFT sizes allowed in 3GPP LTE and NR, i.e. This may limit the evolution of the standard to use different RS frequency densities. For example, in some implementations, a frequency density of one eighth of a resource element will not be allowed for RS signals, because no matter what the value of M is, Neither of them fits the formula. In addition, in some implementations, this technique does not provide any possibility to control the PAPR.

[0182] The complexity, measured by the number of complex multiplications and not taking into account the equalization step (common to all techniques), is given by (ML)log2(ML).

[0183] Some implementations involve RS insertion by subcarrier puncturing. In some implementations, to overcome the above problems, it may be more attractive to use the same DFT size in all DFT-s-OFDM symbols for post-DFT insertion of RS.

[0184] Figure 4 is a diagram illustrating an example process 400 for RS insertion achieved by subcarrier puncturing via zero padding, wherein data symbols 404 are padded with zeros 450 up to size M and an M-point DFT 406 is performed, after which L data subcarriers 452 are punctured at the output of the DFT 406 stage, and RS symbols 402 are inserted after the DFT 406 and before subcarrier mapping 408, IDFT 410, and PS 412.

[0185] In some implementations, the process may be adapted to insert distributed RSs at periodic positions in the frequency domain. In this case, subcarrier puncturing may result in some interference appearing in the DFT-s-OFDM time domain signal in the form of periodic terms due to the periodic positions of the RS subcarriers, and in some implementations, these interferences are compensated upon reception before demodulating the data symbols. In some implementations, such interference terms may cause an increase in both bit error rate (BER) statistics and PAPR. In some implementations, the increase in PAPR due to interference terms is added to the increase in PAPR due to RS insertion due to non-contiguity of data subcarriers after DFT. In some implementations, the PAPR increase may be detrimental in multi-user scenarios based on DFT-s-OFDM, where each user is assigned a different subcarrier cluster in the frequency domain, for example, because the PAPR of multi-cluster transmissions may deteriorate as the dynamic load of the network increases.

[0186] Some techniques for post-DFT insertion based on subcarrier puncturing may rely on the receiver to perform interference suppression for data recovery and do not provide any means to reduce PAPR.

[0187] In some implementations, inserting a distributed RS pattern in the frequency domain may have several benefits compared to a block RS pattern. For example, a distributed RS pattern has higher resource utilization efficiency compared to a block RS pattern in pre-DFT RS insertion, as is evident, for example, in 5G NR DM-RS for PUCCH format 3 with up to 50% overhead. In addition, distributed RS may have the advantage of providing more flexibility than block RS to allocate multiple-input / multiple-output (MIMO) orthogonal layers. In multi-user (MU)-MIMO, the use of hybrid beamforming at high frequencies may require digital precoding to perform spatial multiplexing on the signals when the beams overlap spatially. In single-user (SU)-MIMO, future device evolution may result in an increase in the number of supported MIMO layers. In both cases, DM-RS signals can be more flexibly mapped to resources when allocated in the frequency domain.

[0188] Current LTE and NR wireless cellular systems using DFT-s-OFDM only consider pre-DFT insertion of RS based on occupying full OFDM symbol resource allocation (with poor resource utilization) or multiplexing with data signals in the time domain (cannot be interleaved with data in the frequency domain) in order not to compromise the low PAPR of a single carrier waveform.

[0189] Future use of post-DFT insertion of RSs, as an alternative solution to avoid the spectral inefficiencies associated with the use of pre-DFT insertion of RSs, may involve various disadvantages of post-DFT insertion of RSs described herein.

[0190] Therefore, it may be desirable to address potential challenges of post-DFT insertion such as increased PAPR, limitations in available RS frequency patterns, and use of different DFT sizes for symbols carrying and not carrying RS based on interleaved RS insertion.

[0191] Furthermore, it may be desirable to address potential challenges of RS insertion achieved by subcarrier puncturing, such as where RS insertion achieved by subcarrier puncturing with zero padding does not provide any ability to control PAPR and performance except through optimized receiver structure.

[0192] Some implementations provide an adaptive framework for pre-DFT insertion and post-DFT insertion of distributed RS in DFT-s-OFDM at periodic locations in the frequency domain, for example, to provide flexibility in RS frequency patterns while providing a means to minimize PAPR and optimize demodulation performance. In addition, some implementations provide WTRU assistance, for example, in terms of UE capability signaling, measurements to support more efficient power allocation schemes, and / or feedback to base station decisions.

[0193] As used herein, it is assumed that L reference symbols (or pilots) are inserted in a distributed manner into blocks of M consecutive subcarriers and multiplexed with (ML) modulated data symbols {d[0], ..., d[ML-1]}. Depending on the application, the pilots can be complex values ​​known a priori or blank symbols.

[0194] The subcarrier positions can be regularly spaced Insert pilots at, where p can be the set and represents a priori known frequency shift. The combined frequency pattern may also be in a state with two a priori known frequency shifts Form (ML) will be a multiple of L.

[0195] Figure 5 is a flow chart illustrating a high-level process 500, which is further illustrated in greater detail with respect to an exemplary implementation herein. Figure 5 In the example of , the transmitting node 502 and the receiving node 504 may first exchange information, for example, as part of the initial setup 506 and capability negotiation 508. The information may include, but is not limited to, any one or more of the following elements, which may relate to and / or indicate their RS insertion capabilities: support for pre-DFT RS insertion; support for post-DFT RS insertion based on IFDMA; support for RS insertion based on subcarrier puncturing via a padding sequence, and the supported padding sequence structure; support for fixed or adaptive RS sequences, and the RS sequences supported in the adaptive case; PA-related information, such as PA type / category or PAPR requirement / preference; and / or demodulation-related information, such as support for SIC with a maximum number of iterations, or any other detection-related parameters.

[0196] In some specific implementations, after the initial establishment 506 is completed, the transmitting node may provide the receiving node with RS insertion configuration parameters 510, for example, via DCI-related signaling or MAC CE. The RS insertion configuration parameters 510 may include information indicating, for example, RS insertion type, filling sequence structure detection mode (e.g., blind vs. explicit), or filling sequence structure identifier, or any other information required for RS insertion technology. In some specific implementations, the RS insertion type may be dynamically selected by the transmitting node 502 during RS insertion selection 512 from any one or more of several options such as the following: pre-DFT RS insertion of full RS symbols, pre-DFT RS insertion based on IFDMA, post-DFT RS insertion based on filling sequence adaptation, post-DFT RS insertion with RS sequence adaptation, and / or post-DFT RS insertion based on filling sequence adaptation and RS sequence adaptation. In some specific implementations, the transmitting node 502 may decide to switch between these alternatives based on, for example, available transmit power, PAPR, complexity and / or based on feedback reports and / or signaling information obtained from the receiving node 504 (which may include, for example, information about demodulation performance, PAPR measurements, capability information, preferred RS insertion type, preferred fill sequence structure type and / or similar indications).

[0197] After RS ​​insertion 514, data 516 may be sent from the sending node 502 to the receiving node (eg, on a suitable channel 518).

[0198] In some implementations, after data transmission and RS insertion 514, the receiving node 504 performs data reception 520 and provides feedback 522 (e.g., in an evented, triggered, or periodic manner) to assist the transmitting node 502 in selecting the most appropriate RS insertion technique for the receiving node 504 to use.

[0199] In some implementations, the transmitting node 502 may also dynamically update 524 some or all of the configuration parameters related to RS insertion (e.g., based on and / or in response to feedback 522 from the receiving node 504, such as a fill sequence structure identifier, RS sequence type, or any other suitable feedback).

[0200] (For example, it can be related to Figure 5 Various RS insertion techniques (used with the implementations shown and described) are described herein (eg, with respect to various example implementations).

[0201] Some implementations involve pre-DFT RS insertion based on IFDMA. For example, some implementations include pre-DFT insertion of RS based on appropriate multiplexing of data and RS symbols in an interleaved manner before the DFT stage. Some implementations include insertion of distributed RS by the transmitting node.

[0202] Figure 6 600 is a flowchart illustrating a process 600 in which a transmitting node inserts a pre-DFT RS based on an interleaved frequency division multiple access (IFDMA) multiplexing of RS and data 602. A vector of time domain pilots 604 is created by concatenating M / L repetitions of L RS symbols and further applying a frequency offset of p subcarriers. Optionally, a permutation 606 is applied to the complex modulated data symbols, and the result is divided into a continuous set of L symbols, where each set is frequency shifted by a certain number of subcarriers, which should be different from the pilot frequency shift p and lower than L. The frequency-shifted pilots are summed together with the frequency-shifted complex modulated data symbols via IFDMA multiplexing 608, and an M-point DFT 610 is performed. Standard DFT-s-OFDM processing 612 then generates a time domain waveform 614.

[0203] Figure 7 is a more detailed processing step for illustrating the pre-DFT RS insertion of the pre-DFT RS implemented by the transmitting node based on IFDMA (for example, corresponding to Figure 6 A flowchart of the steps shown and described.

[0204] In this example, the sending node first applies an optional permutation to the data symbol d704 702 to provide a permuted time domain symbol at a time different from zero The IFDMA multiplexer 706 then creates a The pilot vector where {p i , i=0,…,L-1} represents the time domain complex pilot symbol 708, and then the data vector has the components in the following equation:

[0205]

[0206] where k l Is a collection elements such that k l ≠p to ensure that there is no overlap between the pilot 708 and the data 704. The vector s is then created as the sum of the pilot 708 and the data 704, as shown in the following equation:

[0207]

[0208] Afterwards, the transmitting node applies S / P 710, DFT 712, IFFT 714, and then P / S and CP 716 to generate s T [n] (time domain signal) for transmission on channel 718.

[0209] Figure 8 8 is a diagram illustrating an example multiplexing 800 of RS 804 (pilot) and data 802 in pre-DFT insertion based on IFDMA. Figure 8 In , k is the subcarrier index value in the frequency domain, and i is the sample value in the time domain. Figure 8 An example arrangement of RS 802 (pilot) and data 802 is illustrated, which may be implemented, for example, as described with respect to Figure 6 The IFDMA multiplexing block 608 is shown and described. Figure 8 After multiplexing 800 as shown, the M-point DFT can be applied to the vector s( Figure 8 The output of ) and standard DFT-s-OFDM processing then generates a time domain signal including data and distributed RS. As in standard DFT-s-OFDM, by simply including multiple signals as input to Figure 7 The N-point IFFT blocks shown and described (eg, at the appropriate center subcarriers) may multiplex the multiple signals in frequency.

[0210] Some implementations involve data detection performed by a receiving node.

[0211] Fig. 9 is a flow chart illustrating an example process 900 for performing data detection in pre-DFT RS insertion based on IFDMA by a receiving node. Fig. 9 In the example of , the receiving node performs the following steps for data detection. Fig.10 Further details about Fig. 9 The process steps shown and described, Fig.10 is a flow chart illustrating receiving node processing steps for data detection in IFDMA based pre-DFT RS insertion.

[0212] exist Fig. 9 In the example of , in step 904, the receiver demodulates the DFT-s-OFDM symbol and performs channel estimation and equalization of the time domain waveform 902 to produce complex multiplexed data and pilot symbols.

[0213] In some implementations, the permutation step is undone in step 906, and thereafter a parallel L-point IDFT set may be performed on the data symbol set in step 908, after which the data symbol set is concatenated in step 910 to produce estimated data 912. Alternatively, in some implementations, a single DFT is performed according to the prior art to recover the interleaved data. In this case, undoing the permutation in step 906 refers to performing an inverse permutation operation, i.e., an operation described by the mathematical inverse of the permutation operation performed by the transmitting node.

[0214] Fig.101 is a flow chart of an example flow chart of a receiving node processing steps 1000 for data detection in pre-DFT RS insertion based on IFDMA in a receiving node. In more detail, the flow chart substantially corresponds to Fig.10 The example process 900 is shown and described. In some implementations, the receiver receives a time domain receive waveform s from the channel 1002. R [n] and perform DFT-s-OFDM demodulation block 1004 (e.g., inverse CP and S / P in step 1006, FFT in step 1008, and channel estimation 1010 and equalization 1012 of the time domain waveform). The permutation is undone in step 1014. In some implementations, the subcarriers are then deinterleaved in step 1016, for example, by selecting Groups have indexes L subcarriers, where and k l ≠p.

[0215] In some implementations, the subcarrier groups may undergo A set of parallel L-point IDFTs are used to generate L complex symbols. A collection of data that was previously segmented on the sending side: and in represents the complex estimated data symbol after equalization, and i=0, ..., ML-1. In some implementations, these segments are concatenated in step 1020 to deliver a received estimated data block 1022 as in the following expression:

[0216] Alternatively, in some implementations, the receiver can perform a single DFT according to prior art techniques to recover the interleaved data.

[0217] The complexity of the detection process after the equalization step in terms of complex multipliers (common in the prior art) can be described as follows. First, assume that the detection process is based on If there are L parallel IDFTs and no permutation is considered, the complexity can be given by the following equation:

[0218]

[0219] This complexity is lower than or equal to the complexity of the interleaved RS insertion described previously. In this case, requiring an L-point DFT forces the hardware to perform a DFT size adaptation depending on the presence of RS in the symbol. An alternative technique based on a single M-point IDFT is more convenient and has a complexity given by the following equation:

[0220]

[0221] Here, advantageously, a single DFT size M is required for all DFT-s-OFDM symbols.

[0222] Some implementations involve post-DFT RS insertion based on padding sequence adaptation. Such implementations may include post-DFT RS insertion techniques based on subcarrier puncturing and selection of appropriate one or more padding sequence structures appended to data symbols before the DFT stage. Such implementations may be referenced based on the type of transmitting node (e.g., base station or user equipment) and the type of padding sequence adaptation (e.g., dynamic or semi-static).

[0223] Some implementations include dynamic insertion of distributed RSs by the base station with the assistance of user equipment feedback.

[0224] Fig.11 1 is a flow chart illustrating an example process 1100 for dynamic RS insertion at the BS side. Fig.11 In the example of FIG. 1 , a base station (BS) performs the following example steps for dynamic insertion of a distributed RS.

[0225] exist Fig.11 In an example of , in step 1102, the BS dynamically selects one or more padding sequences. In some implementations, the padding sequence is selected by the BS from a set of padding sequence structures, for example, specified in a predetermined codebook, based on a PAPR measurement 1104 performed by the BS (e.g., based on signaling 1106 with the WTRU). The signaling 1106 may include, for example, time domain measurements performed by a WTRU (e.g., a user equipment (UE)) on a current symbol and / or several previous symbols for a feedback report, which is transmitted by the WTRU in a periodic, semi-periodic, on-demand, or event-based manner. In some implementations, the padding sequence is selected by the BS from the set of padding sequence structures based on a PseqS report 1120 from the WTRU. In step 1108, the padding sequence is appended to the modulated data symbol.

[0226] In some implementations, in step 1110, a permutation is optionally applied to the resulting data block and padding symbols, for example in such a way that the complex modulation symbols after the permutation are uncorrelated and the permuted positions of the padding symbols are different from each other under modulo L.

[0227] In some implementations, a DFT is performed in step 1112. In some implementations, an M-point DFT is performed, and the subcarriers at the target pilot positions are punctured and replaced with L RS symbols (which can be complex-valued or blank). In some implementations, standard DFT-s-OFDM processing is then performed to generate a time domain waveform 1114, and PAPR measurements 1104 are performed by the BS, for example, to refine the padding sequence selection step 1102 in subsequent time intervals.

[0228] In some implementations, the BS may optionally signal the WTRU in signaling 1106 the padding sequence structure used. In some implementations, the padding sequence structure is signaled based on one or more padding sequence structure identifier (PSeqS ID) fields. In some implementations, the PSeqS ID field may be transmitted once during session establishment and / or may be dynamically updated during data transfer. In some implementations, the sequence identifier may be blindly detected by the WTRU without explicit signaling.

[0229] In some embodiments, the BS may transmit multiple PSeqS ID fields or combined PSeqS ID fields to the WTRU in signaling 1106, for example, including one or more indications of one or more padding sequence structures to be used for each TRP (for example, in a case where multiple transmit / receive points (TRPs) are available to transmit data channels (for example, by using full / partial / non-overlapping time-frequency resources (for example, using different DL beams)) using different or the same transport blocks, different or the same redundant versions of the same transport block, or different or the same codewords, etc.).

[0230] Fig.12 is an example and about Fig.11 The process 1100 shown and described corresponds to a flowchart 1200 of the processing on the BS side. Fig.11 The steps in the flowchart are Fig.12 Without loss of generality, the detailed description here considers the case of a single filling sequence. Fig.12 Also shown are S / P 1210, IFFT 1214, P / S and CP 1216, and channel 1218 over which the time domain waveform 1114 is transmitted.

[0231] With respect to the selection of a padding sequence in step 1102, in some implementations, the BS receives one or more feedback reports from the WTRU (e.g., UE) in signaling 1106. In some implementations, the feedback reports include an indication of a preferred padding sequence and / or demodulation performance. In some implementations, this, together with, for example, PAPR measurements obtained by the BS or time domain measurements performed by the WTRU in the current symbol and / or several previous symbols, may be used to select in step 1102 the type and / or length of the padding sequence that best meets the objectives of the service / application. In some implementations, the padding sequence to be used may be indicated in a predefined codebook that may be known a priori to the BS and / or WTRU.

[0232] In some implementations, the WTRU-side time domain measurements may include any metric for measuring the deviation of the signal from a pure single carrier, such as the absolute magnitude of the interference caused by RS puncturing and insertion, or the time domain autocorrelation of the signal after interference cancellation. Both of these may indicate how far the signal is from a single carrier and may help the BS control the selection of padding sequence structure. In some cases, the absolute magnitude of the interference caused by RS puncturing and insertion and the time domain autocorrelation of the signal after interference cancellation may yield better insight than the BS-side PAPR measurements, for example because the PAPR may be averaged over a large number of DFT-s-OFDM symbols to improve accuracy.

[0233] In some implementations, PAPR measurements and time domain measurements may be performed on the current symbol and / or several previous symbols. The number of symbols used for PAPR measurement / time domain measurement may be indicated by the BS in the time domain measurement configuration information, e.g., DCI or semi-periodic / periodic RRC configuration message. In some implementations, if the time domain measurement is performed by the WTRU, the measurement report may be included in a time domain report message transmitted to the BS via a control channel or a data channel, e.g., via UCI or as part of the PUSCH. In some such cases, the BS may configure the timing of the time domain report message, e.g., via time domain report configuration information in the DCI or an RRC time domain report configuration message. In some implementations, the WTRU may perform time domain measurements on a time domain signal that is generated after equalization and discarding all frequency subcarriers not allocated to the WTRU, e.g., in order not to be affected by the PAPR of signals for other users.

[0234] In some implementations, the WTRU may be configured to provide periodic measurement reports, semi-persistent reports, or event-based reports. Alternatively, in some implementations, the WTRU may receive a message from the BS (e.g., in signaling 1106) requesting a time domain measurement report. In some implementations, the WTRU may determine not to transmit a time domain report message if the measurement result is unreliable, for example, due to excessive noise or channel impairments. In some implementations, an indication not to transmit a time domain report message may be signaled to the BS, for example, via an RRC Time Domain Measurement Configuration Reject or a Null Time Domain Report message.

[0235] In some implementations, PAPR and demodulation performance may be traded off, e.g., depending on the application. For example, performance-critical applications may prioritize BER / BLER at the expense of some PAPR degradation, while other applications intended for use with low-cost devices where performance is not so critical may prioritize PAPR to maximize energy efficiency.

[0236] In some specific implementations, the sequence selection step 1102 may be based on one or more of the following criteria, but other possibilities are not excluded, depending on the specific implementation: the set of a priori known filling sequence structures included in the codebook may first be classified in terms of their PAPR and performance characteristics; the BS and the WTRU may know both the sequence and its related characteristics a priori; after measuring the PAPR of a given DFT-s-OFDM symbol or symbol set in one or several previous time intervals, the BS may determine to change the filling sequence to another filling sequence with a lower PAPR based on a target PAPR set semi-statically or dynamically by the application or configured by a higher layer; if the metric contained in the feedback report exhibits worse performance than the target set by the application or configured by a higher layer, the BS may determine to switch to another filling sequence characterized by better performance; and / or the BS may also consider explicit indications from the WTRU to switch to a preferred filling sequence during the sequence selection process.

[0237] In some implementations, in addition to being based on PAPR and performance, the sequence selection step 1102 may also be semi-statically or dynamically based on instantaneous network / cell conditions. For example, in some implementations, the PAPR in a multi-user scenario based on DFT-s-OFDM may depend on the number of active users, for example, where each user includes a cluster of contiguous subcarriers. In some implementations, the cell load may dynamically shift the sequence selection to optimize PAPR or performance, for example, depending on the power budget on the BS side. In some implementations, the sequence selection may also involve a machine learning (ML) algorithm that is trained to suggest a fill sequence based on one or several PAPR measurements, network / cell load, and / or feedback reports from the WTRU. In some implementations, the sequence selection process may be intended to optimize PAPR or performance based on cell load (e.g., depending on the power budget on the BS side) (e.g., if the BS power is constrained, high cell load may trigger sequence selection based on PAPR optimization).

[0238] In some implementations, the time scale for the fill sequence selection step 1102 may range from very long (connection-based) to very fast (symbol-based) and be adaptive. In some implementations, different time scales are used depending on the application and these time scales may be affected by the periodicity of the feedback reports transmitted by the WTRU. For example, in some implementations, very long means, for example, on the order of minutes or hours, for example, as determined by the duration of the connected session. In some implementations, very fast means, for example, on the order of microseconds, for example, as determined by the duration of a symbol. In some implementations, the periodicity of the PSeqS ID indication (if present) may be equal to the time scale of the sequence selection (e.g., to provide a signaling indication with the same periodicity as the sequence selection process), for example, in such a way that a signaling process updated over a long period of time corresponds to a long time scale in the sequence selection process (e.g., on the order of minutes or hours, for example, as determined by the session duration) and vice versa.

[0239] In some embodiments, where multiple transmit / receive points (TRPs) may establish wireless connections to the WTRU, the BS may (e.g., in signaling 1106) transmit multiple PSeqS ID fields or a combined PSeqS ID field to the WTRU, for example, including an indication of one or more padding sequence structures for each TRP, for example, via a single DCI, multiple DCIs (e.g., associated with different TRP transmissions), and / or as part of a radio resource control (RRC) establishment, and / or dynamically updated during data delivery within the DCI.

[0240] In some embodiments, the received uplink PSeqS report 1120 may include, but is not limited to, any one or more of the following indications from the WTRU side: a preferred padding sequence structure identifier (PSeqS ID); a mean square error (MSE) of interference estimation during the signal detection process; a signal-to-noise ratio (SNR) after detection; high-level (e.g., from a protocol layer above the physical layer, such as the MAC layer or the RLC layer) performance metrics (e.g., such as a bit error rate (BER) or a block error rate (BLER) before or after forward error correction (FEC)); and / or metrics related to the convergence of a successive interference cancellation (SIC) algorithm (e.g., the number of iterations or the residual error).

[0241] In some implementations, for example, when more than one TRP has established a connection with the WTRU, multiple PSeqS reports 1120 may be transmitted independently by the WTRU to the multiple TRPs. In some implementations, each such report may include any one or several of the above indications for any one of the TRPs involved. In some implementations, a single (e.g., joint) report may be transmitted that includes the PSeqS reports 1120 sent for one or more TRPs.

[0242] In some implementations, the PSeqS reports 1120 may be transmitted by the WTRU in a periodic, semi-periodic, on-demand, and / or event-based manner. In some implementations, when PSeqS reports are transmitted periodically, their periodicity may follow the rate of change of the wireless channel and / or changes in WTRU performance (e.g., the periodicity should be sufficient to respond to changes in the channel and / or WTRU performance).

[0243] In some implementations, the padding sequence may have a length different from L. In some such cases, the number of data symbols is different from (ML) to match the DFT size of the transform pre-decoding stage, M (e.g., the sum of the padding sequence length and the number of data symbols should be equal to the DFT size). In some implementations, a padding length higher than L may result in less than (ML) available data symbols (which can be compensated by adjusting the available parity bits after the FEC encoding stage), but also a better estimate of the interference from RS insertion. In some implementations, a padding length lower than L may result in higher spectral efficiency, but also a worse interference estimate at the receiver. In some implementations, the BS may therefore alternate between larger or smaller padding sequences without changing the sequence type. In some implementations, the various techniques herein are also effective for cases where a padding length different from L is used.

[0244] Without loss of generality, this solution and other solutions consider padding sequences of length L to simplify the description.

[0245] With respect to appending one or more padding sequences to the data block in step 1108, in some implementations, one or several padding sequences c[m]={c[0], ..., c[L-1]} may be appended to the end of a data block d[m]={d[0], ..., d[ML-1]} that is input to the DFT stage such that the combined block x={d[0], ..., d[ML-1], c[0], ..., c[L-1]} has a length M. In some implementations, the use of a padding sequence allows for a pattern with regular spacing. RS insertion, where p can be a set In some implementations, using two concatenated filling sequences c1 and c2 may enable having two a priori known frequency shifts Form The RS pattern produces a complex block of the form x = {d[0],…,d[ML-1],c1[0],…,c1[L-1],c2[0],…,c2[L-1]}.

[0246] The symbol positions of the padding sequence are represented as {i k =M-L+k, k=0,…,L-1}, for example, some examples of filling sequences include a constant envelope sequence, a sequence with sign-inverted data symbols, a sequence with phase-shifted data symbols, and / or a blank field.

[0247] Constant envelope sequences may include any sequence with a constant amplitude, such as Zadoff-Chu, m-sequences, or any similar sequence that may fit this type. In some implementations, these sequences may minimize PAPR, but do not add any additional information to the modulated data symbols, thus leaving less energy for the data and thus introducing some performance degradation.

[0248] The sequence of data symbols with sign inversion may include a padding sequence equal to L selected modulated data symbols with sign inversion (other possibilities may also be defined), as shown in the following equation:

[0249] c[i k ]=-d[(i k +L)mod M]

[0250] In some implementations, sequences with sign-reversed data symbols allow some noise reduction at reception by accumulating their complex values ​​with the corresponding data symbols during the interference estimation process. However, the high autocorrelation introduced in the time domain can enhance the spectral components at the pilot positions after the DFT. In some implementations, puncturing introduces additive interference equal to the value of the spectral components at the pilot positions minus, resulting in higher degradation. In some implementations, undesirable autocorrelation can be minimized by a permutation step 1110 that randomizes the padding symbol positions. In some implementations, another way to minimize autocorrelation is to avoid sign reversal of consecutive data symbol blocks by picking data symbols in groups of L samples, for example, as shown in the following equation:

[0251] c[i k ]=-d[(i k +kL)mod(ML)]

[0252] Other possibilities may also occur depending on the specific implementation.

[0253] The sequence having phase-shifted data symbols may include, for example, where the padding sequence involves phase-shifted copies of L selected data symbols, as shown in the following equation:

[0254] c[i k ]=e jθ d[(i k +kL)mod(ML)]

[0255] Here, θ is a priori known phase that can be adjusted to meet different objectives. The sign-reversed case would be a special case where θ=π. In some implementations, a phase shift close to π / 2 can produce better PAPR and slightly higher bit signal-to-noise ratio (Eb / N0) than the sign-reversed case, and in some implementations, a phase shift close to zero can increase autocorrelation while also enhancing noise during the interference estimation process at the receiver. There are many other possibilities by choosing different values ​​for θ.

[0256] A blank field may include, for example, the case where the fill sequence is simply a set of blank symbols, as shown in the following equation:

[0257] c[i k ]=0

[0258] This is described above with respect to RS insertion by subcarrier puncturing, which in some implementations facilitates interference estimation by allowing energy boosting in non-null data symbols to keep power constant, but which in some implementations also introduces higher PAPR than constant envelope sequences.

[0259] The above sequences are examples that illustrate the tradeoffs between performance, PAPR, and detection complexity. In some implementations, eg, depending on the implementation, codebooks of padding sequences different from those described may be used without departing from the present disclosure.

[0260] Regarding the permutation step 1110, in some implementations, a permutation may be applied to randomize the resulting block {x[i k ],i k =0, ..., M-1} and avoid undesirably high residual autocorrelation before the DFT stage to produce a complex symbol block (keeping the single sequence case for simplicity), as shown in the following equation:

[0261]

[0262] in represents any permutation satisfying the following properties:

[0263]

[0264] That is, in some implementations, the complex modulation symbols after the permutation step 1110 are uncorrelated, and the permutation positions of the symbols of the padding sequence are different from each other modulo L. Here, i k and i j denotes the index of the complex symbol before permutation, and mod L denotes the modulo L operation, i.e., the remainder after division by L. In some implementations, for example, when the padding sequence depends on the data (e.g., as in the case of sign reversal in the above-mentioned phase shift case), the independence of the complex symbols can be achieved by positioning the complex symbols differently after permutation for different time instances. In some implementations, considering that the interference from subcarrier puncturing is periodic in time with a period L, the padding symbols can be used by the receiver to estimate such interference if (e.g., only if) the positions after permutation are different modulo L.

[0265] Fig.13 is an example of Fig.11 and Fig.12 An illustration of the sequence filling step 1108 and the permutation step 1110 discussed.

[0266] After subcarrier puncturing and RS insertion, in some implementations, an M-point DFT may be performed on the permuted block {d′[0], …, d′[M-1]}. In some implementations, after performing the M-point DFT, subcarriers located at expected pilot positions may be punctured and a priori known RS symbols may be inserted in the frequency domain.

[0267] Fig.14 is an example of Fig.11 , Fig.12 and Fig.13 A diagram showing details of the S / P step 1210, DFT step 1112, subcarrier puncturing, and RS insertion step 1113 shown and described. In some implementations, for example, the inserted RS may include complex a priori known symbols or blank symbols, depending on the application. In some implementations, the blank symbols may be used to reserve resource elements in 5G NR intended for use, for example, in other MIMO layers or antenna ports, or for channel acquisition from other cells.

[0268] In some implementations, the DFT-s-OFDM processing continues after the subcarrier puncturing and RS insertion step 1113 to generate a DFT-s-OFDM time domain waveform s T [n], including mapping to the selected subcarriers in the frequency domain, inverse DFT of size N (IFFT step 1214), parallel to serial conversion, and addition of a cyclic prefix (P / S+CP step 1216).

[0269] Fig.15 is a flow chart illustrating details of further steps for generating a DFT-s-OFDM time domain waveform, including as to Fig.11 , Fig.12 , Fig.13 and Fig.14 Shown and described are an IFFT step 1214 and a P / S+CP step 1216. Note that further processing steps may be included depending on the specific implementation.

[0270] With respect to PAPR and time domain measurements, in some implementations, the BS may measure the PAPR of the time domain signal, and this value may be used together with statistics of the PAPR that may have been obtained at the current time or at previous time as the final input for selecting a padding sequence, e.g., as described with respect to Figure 5 In some implementations, the time domain measurements performed at the WTRU may be reported to the BS, for example, via a time domain report message. In some implementations, the configuration of the number of symbols used for the time domain measurements and the timing of the report messages may be provided by the BS, for example, in a time domain measurement configuration message and / or a time domain report configuration message, respectively.

[0271] In some implementations, time domain measurements may be performed at the WTRU on the time domain received signal after equalization, or before or after interference cancellation due to subcarrier puncturing and RS insertion. In some implementations, the WTRU may determine not to transmit a time domain report message, for example, if the measurement is unreliable due to, for example, excessive noise or channel impairments. In some implementations, this may be signaled to the BS, for example, via an RRC Time Domain Measurement Configuration Reject or Null Time Domain Report message.

[0272] With respect to BS-to-WTRU signaling and WTRU-to-BS signaling, in some implementations, the BS may optionally transmit control information to the WTRU regarding one or more used padding sequence structures, for example, with a periodicity given by the time stamp of the sequence selection procedure. In some implementations, the padding sequence structure identifier (PSeqS ID) field may be transmitted once (e.g., a default one) during session establishment, as part of, for example, radio resource control (RRC) establishment, and / or dynamically updated during data transfer within downlink control information (DCI). Alternatively, in some implementations, a set of supported padding sequence structures with their identifiers may be provided to the WTRU using higher layer signaling (e.g., RRC), for example, along with an initially active / selected sequence that may be dynamically switched to another sequence for which the network may indicate the selected sequence to the WTRU using a MAC CE or / and DCI message. In some implementations, the WTRU may also perform blind detection of the used padding sequence without explicit signaling.

[0273] In some implementations, the periodicity indicated by the PSeqS ID may be equal to the timestamp of the fill sequence selection procedure, for example, in such a way that a longer timestamp (e.g., determined by the session duration, e.g., on the order of minutes or hours) corresponds to a signaling procedure that is updated over a longer period of time, and vice versa. The PSeqS ID information may be transmitted in different ways. For example, in some implementations, RRC-based signaling may be used when the sequence selection operates on a very long timestamp, while DCI-based signaling may be used, for example, when the sequence is updated on a per-slot basis. In some implementations, other signaling mechanisms with different periodicities are also possible, for example, using MAC CE signaling. In some implementations, if blind detection is used on the WTRU side, the blind detection does not require any signaling of the PSeqS ID from the BS.

[0274] Fig.16 is an example of BS 1602 and WTRU 1604 (in Fig.16 1600 between a UE and a UE, including downlink data 1690 (eg, for dynamic RS insertion at the BS side). In some implementations, the feedback loop 1600 illustrates the feedback loop with respect to Fig.11 The steps shown correspond to those described.

[0275] In the feedback loop 1600, a PSeqS report 1620 is transmitted by a WTRU (eg, UE) to a BS 1602, for example, in a periodic, semi-periodic, on-demand, or event-based manner, for example, to assist the BS in a sequence selection procedure.

[0276] In some implementations, an optional PSeqS ID 1630 may also be transmitted to the WTRU periodically and may include information about the padding sequence used. In some implementations, the BS may also transmit multiple PSeqS ID fields or a combined PSeqS ID field to the WTRU, which may include an indication of one or more padding sequence structures to be used for each TRP. In some implementations, for example, when no PSeqS ID field is transmitted by the BS or the multiple TRPs, the WTRU may perform blind detection of the one or more padding sequence structures. In some implementations, multiple PSeqS reports 1620 may also be transmitted by the WTRU to different TRPs in the event that multiple TRPs have established connections with the WTRU. Alternatively, in some implementations, the WTRU may be configured to transmit a single (e.g., joint) report containing PSeqS reports 1620 for one or more TRPs. In some implementations, the PSeqS report 1620 may be transmitted to the BS, for example, via a medium access control control element (MAC CE), but in some implementations, other ways of transmitting the PSeqS report 1620 are possible.

[0277] In some implementations, the BS may transmit additional signaling information about the number of symbols used for time domain measurement, such as, for example, time domain measurement configuration information (e.g., using DCI), or semi-periodic / periodic RRC configuration messages (e.g., in a time domain measurement configuration message 1632). In some implementations, this may enable time domain measurements to be performed on the WTRU 1604 side, if desired. In some such cases, the WTRU 1604 may transmit the time domain measurement results to the BS, for example, via an appropriate time domain report message 1622, and the BS may transmit additional timing information, such as via time domain report configuration information in a DCI or an RRC time domain report configuration message (e.g., in a time domain report configuration message 1634).

[0278] In some implementations, the time domain report message 1622 may be transmitted by the WTRU to the BS via a control channel or a data channel (e.g., via UCI or as part of PUSCH) or to multiple TRPs in case of multi-TRP operation. In some implementations, the WTRU may be configured with periodic time domain report messages or fill sequence structure reports, for example, using higher layer signaling, such as RRC signaling. Alternatively, in some implementations, the WTRU may be configured with semi-persistent reporting using RRC signaling, where a set of reports may be configured and a DL MAC CE or DCI may be used to activate / deactivate one of the reports in the configured set. In some implementations, for periodic / semi-persistent reporting, the WTRU may be configured with uplink resources (e.g., via PUCCH) to transmit the report. Alternatively, in some implementations, the WTRU may (e.g., dynamically) receive a MAC CE or DCI message requesting a time domain measurement report. In some implementations, the WTRU may utilize the next available PUCCH resource or use the uplink resources configured on the uplink shared channel (e.g., PUSCH) to transmit a time domain report message or fill in a sequence structure report. In some implementations, in the case where the WTRU does not have any configured uplink resources, the WTRU may transmit a scheduling request to request the allocation of uplink resources on the uplink shared channel to transmit the report. In some implementations, a new MAC CE or / and DCI may be configured for this purpose. In some implementations, a new WTRU identifier (e.g., X-RNTI) may be configured to the WTRU on a unique or group basis, for example, to decode a DCI containing a report configuration. In another example, the WTRU may be configured with event-based reporting. In some implementations, the WTRU may be configured with one or more thresholds, reception times, or durations (e.g., trigger times) included in the report for measurement. In some implementations, the WTRU may be configured to transmit a report when an event is triggered, for example, when a measurement result (e.g., MSE, SNR, BER, etc.), or an average of a configured number of measurements, or an average of a number of measurements taken over a configured duration, meets a configured threshold (e.g., is lower than, higher than, or equal to the configured threshold as required). In some implementations, event-triggered or event-based reports may be transmitted via UL MAC CE, UL RRC, or UCI messages.

[0279] Some implementations involve semi-static insertion of distributed RS at the BS side without WTRU feedback.

[0280] Fig.17 1700 is a flow chart illustrating an example process 1700 for semi-static RS insertion at the BS side. Fig.17In the example of FIG. 5 , the BS performs the following example steps for semi-static insertion of a distributed RS.

[0281] In some implementations, one or more padding sequences may be selected (e.g., semi-statically selected) by the BS in step 1102. In some implementations, the padding sequence is selected by the BS (e.g., based on a predefined strategy and / or PAPR measurements 1704 performed by the BS on the current symbol and / or several previous symbols) from a set of padding sequence structures specified in a predetermined codebook. In step 1708, the one or more padding sequences may be appended to the modulated data symbols.

[0282] In some implementations, in step 1710, a permutation is optionally applied to the resulting data block and padding symbols, for example in such a way that the complex modulation symbols after the permutation are uncorrelated and the permuted positions of the padding symbols are different from each other under modulo L.

[0283] In some implementations, an M-point DFT is performed in step 1712. In some implementations, the subcarriers at the target pilot positions are punctured and replaced with L RS symbols (which can be complex-valued or blank). In some implementations, standard DFT-s-OFDM processing is then performed to generate a time domain waveform 1714, and PAPR measurements 1704 are performed by the BS, for example, to refine the padding sequence selection step 1702 in subsequent time intervals.

[0284] In some implementations, the BS may optionally signal (e.g., using one or more Padding Sequence Structure Identifier (PSeqSID) fields) to the WTRU (e.g., in signaling 1706) an indication of the one or more padding sequence structures to be used, which may be transmitted once during session establishment and / or dynamically updated during data transfer, or alternatively, the one or more sequence structure identifiers may be known a priori by both the transmitter and receiver or may be blindly detected by the receiver without explicit signaling. In the case where multiple transmit / receive points (TRPs) may establish a wireless connection to the WTRU, in some implementations, the BS may transmit multiple PSeqS ID fields or a combined PSeqS ID field to the WTRU, for example, including an indication of one or more padding sequence structures to be used for each TRP.

[0285] Note that flow 1700 illustrates an example process on the BS side, which is similar to that of FIG. 17 except that there is no PSeqS report from the WTRU and the signaling information is unidirectional from the BS to the WTRU. Fig.11 The process is shown and described.

[0286] In some implementations, the selection of the padding sequence in step 1702 is based on higher layer signaling, PAPR measurements performed by the BS on the current symbol and / or several previous symbols, a semi-static strategy, and / or any other suitable strategy that does not require feedback from the WTRU side. Alternatively, in some implementations, both the BS and the WTRU may have a priori knowledge of the one or more padding sequence structures to be used without explicit indication. In some implementations, the padding sequence structure to be used may be included in a predefined codebook known a priori by the BS and the WTRU, for example.

[0287] In process 1700, one or more filling sequences may be semi-statically selected by the BS (based on PAPR measurements performed by the BS on the current symbol and / or several previous symbols) from a set of filling sequence structures specified in a predetermined codebook and appended to the modulated data symbols before the DFT stage in step 1708.

[0288] In some implementations, in the permutation step 1710, permutation is optionally applied to the resulting data block and padding symbols in such a way that the complex modulation symbols after the permutation are uncorrelated and the permuted positions of the padding symbols are different from each other under modulo L.

[0289] In some implementations, an M-point DFT is performed, and the subcarriers located at the target pilot positions are punctured and replaced with L RS symbols (which may be complex-valued or blank) in step 1712.

[0290] In some implementations, standard DFT-s-OFDM processing is then performed to generate a time domain waveform 1714, and PAPR measurements 1704 are performed to refine fill sequence selection in subsequent time intervals.

[0291] In some implementations, the BS may optionally signal (e.g., in signaling 1706) to the WTRU an indication of the one or more padding sequence structures to be used via one or more padding sequence structure identifier (PSeqS ID) fields, which may be transmitted once during session establishment and / or dynamically updated during data transfer, or alternatively, the one or more sequence identifiers may be blindly detected by the WTRU without explicit signaling. In some implementations, for example, in the case where multiple transmit / receive points (TRPs) may be used to transmit data channels using fully / partially / non-overlapping time-frequency resources (e.g., using different DL beams) (e.g., using different or the same transport blocks, different or the same redundancy versions of the same transport block, or different or the same codewords, etc.), the BS may transmit (e.g., in signaling 1706) to the WTRU multiple PSeqS ID fields, or a combined PSeqS ID field, including an indication of the one or more padding sequence structures to be used for each TRP.

[0292] In some implementations, in optional signaling 1706 shown in dashed lines, the BS may communicate to the WTRU the padding sequence structure used, for example, using a padding sequence structure identifier (PSeqS ID) field. In some implementations, the PSeqSID may be communicated once during session establishment (e.g., a default PSeqS ID), for example, as part of RRC establishment, and / or dynamically updated during data transfer within a DCI. Alternatively, in some implementations, a set of supported padding sequences with their identifiers may be provided to the WTRU using higher layer signaling (e.g., RRC), in some implementations along with an initially active / selected sequence, which in some implementations may be dynamically switched to another sequence for which the network may indicate the selected sequence to the WTRU using a MAC CE or / and DCI message. In some implementations, in another alternative, the padding sequence may be known a priori to both the BS and the WTRU, or the WTRU may perform blind detection of the padding sequence used without explicit signaling.

[0293] In some implementations, the BS may also transmit multiple PSeqS ID fields or a combined PseqS ID field to the WTRU, including an indication of the padding sequence structure to be used for each TRP in the event that multiple TRPs have established connections with the WTRU.

[0294] In some implementations, the periodicity of the PSeqS ID indication may be equal to the timestamp of the fill sequence selection process, for example, in such a way that a longer timestamp corresponds to a signaling process that is updated over a longer period of time, and vice versa. In some implementations, the PSeqS ID information may be transmitted in different ways. For example, in some implementations, the PSeqS ID information may be transmitted via RRC-based signaling, for example, in cases where the sequence selection runs on a very long timestamp (e.g., determined by the session duration, such as on the order of minutes or hours), while DCI-based signaling may be used in cases where the sequence is updated on a per-timeslot basis. In some implementations, other signaling mechanisms with different periodicities are also possible. In some implementations, if blind detection is used on the WTRU side, the blind detection does not require any signaling of the PSeqSID from the BS.

[0295] Some implementations involve data detection and interference cancellation on the WTRU side.

[0296] Fig.18 18 is a flow chart illustrating an example process 1800 for WTRU-side data detection and cancellation of interference from RS insertion. Fig.18 In the example of , the WTRU performs the following example steps for interference cancellation and data recovery.

[0297] In some implementations, the WTRU may obtain periodic signaling information 1806 from the BS. In some implementations, the signaling information 1806 includes an indication of one or more padding sequence structures used among the sequence structures included in the predetermined codebook, or alternatively, the WTRU may have information about the one or more sequence structures in advance, or may perform blind detection on the one or more padding sequence structures without explicit signaling.

[0298] In some implementations, a DFT-s-OFDM symbol is received in step 1802. In some implementations, the DFT-s-OFDM symbol includes complex modulated data symbols affected by interference caused by subcarrier puncturing.

[0299] In some implementations, interference is cancelled in step 1804 and complex modulation symbols 1808 are estimated and delivered to higher layers.

[0300] In some implementations, the feedback report 1810 is optionally transmitted to the BS. In some implementations, the feedback report 1810 includes, for example, a PSeqS report transmitted in a periodic, semi-periodic, or on-demand manner, for example, to assist in populating the sequence selection process. In some implementations, the feedback report 1810 includes a time domain report message indicating time domain measurements performed by the WTRU.

[0301] In the example process 1800, both signaling from the BS and feedback reporting to the BS are optional and are depicted with dashed lines.

[0302] Here, similar to Figures 11 to 17 The signaling blocks shown and described, one or more padding sequence structure identifier (PSeqS ID) fields may be received periodically from the BS via control signaling, or may be known a priori on both the BS side and the WTRU side, for example based on a predefined policy. Alternatively, in some implementations, for example, a set of supported padding sequence structures with their identifiers may be provided to the WTRU using higher layer signaling (e.g., RRC), for example, along with an initially active / selected sequence that may be dynamically switched to another sequence for which the network may indicate the selected sequence to the WTRU using a MAC CE or / and DCI message. In some implementations, one or more padding sequence structures may also be inferred by the WTRU via blind detection. In some implementations, the sequence structure may be, for example, an element of a predefined codebook known a priori by the BS and the WTRU, for example, to simplify detection.

[0303] In some implementations, the periodicity of the PSeqS ID indication may be equal to the timestamp of the fill sequence selection process, e.g., in such a way that a longer timestamp (e.g., determined by the session duration, e.g., on the order of minutes or hours) corresponds to a signaling process updated over a longer period of time (e.g., determined by the session duration, e.g., on the order of minutes or hours), and vice versa. In some implementations, the PSeqS ID information may be transmitted by other means. For example, in some implementations, for example, when the sequence selection operates on a very long timestamp (e.g., determined by the session duration, e.g., on the order of minutes or hours), RRC-based signaling may be employed, while, for example, DCI-based signaling may be used when the sequence is updated on a per-slot basis. In some implementations, other signaling mechanisms with different periodicities are also possible.

[0304] In cases where multiple transmit / receive points (TRPs) may establish wireless connections to the WTRU, the WTRU may receive multiple PSeqS ID fields or a combined PSeqS ID field from the BS, including an indication of the padding sequence structure used by each TRP, for example, via a single DCI or as part of a radio resource control (RRC) establishment and / or dynamically updated during data transfer within the DCI.

[0305] In some specific implementations, for example, as in Fig.11In the signaling process shown and described, further signaling may be exchanged between the BS and the WTRU, which may include information about the number of symbols used for time domain measurement in the time domain measurement configuration information using DCI, or semi-periodic or periodic RRC configuration messages. Timing information for time domain measurements may also be conveyed by the BS through, for example, the time domain report configuration information in the DCI or the RRC time domain report configuration message.

[0306] In some implementations, the WTRU may be configured with periodic time domain report messages or fill sequence structure reports, for example, using higher layer signaling, such as RRC signaling. Alternatively, in some implementations, the WTRU may be configured with semi-persistent reporting using RRC signaling, for example, where a set of reports may be configured and a DL MAC CE or DCI may be used to activate / deactivate one of the configured sets of reports. In some implementations, for example, for periodic and / or semi-persistent reporting, the WTRU may be configured with uplink resources (e.g., via PUCCH) to transmit the reports. Alternatively, in some implementations, the WTRU may receive (e.g., dynamically) an on-demand MAC CE or DCI message requesting the report. In some implementations, the WTRU may utilize the next available PUCCH resource to transmit the time domain report message and / or fill sequence structure report, or may transmit using configured uplink resources on an uplink shared channel (e.g., PUSCH). In some implementations, for example, in a case where the WTRU does not have any configured uplink resources, the WTRU may transmit a scheduling request to request allocation of uplink resources on an uplink shared channel to transmit a report. In some implementations, a new MAC CE and / or DCI may be configured for this purpose. In some implementations, a new WTRU identity (e.g., X-RNTI) may be configured to the WTRU (e.g., on a unique or group basis), for example, to decode a DCI including a report configuration. In another example, in some implementations, the WTRU may be configured with event-based reporting. In some implementations, the WTRU may be configured with a threshold, number of receptions, or duration (e.g., trigger time) included in the report for making measurements. In some implementations, the WTRU may be configured to transmit a report when an event is triggered, for example, when a measurement result (e.g., MSE, SNR, BER, etc.) or an average value of a configured number of measurements or an average value of a number of measurements made within a configured duration is lower than / higher than a configured threshold. In some implementations, event-triggered or event-based reporting may be transmitted via UL MAC CE, UL RRC, or UCI messages.

[0307] About Combination Fig.18The receiving DFT-s-OFDM symbol step 1802 is shown and described. In some implementations, the DFT-s-OFDM processing uses the time domain received waveform s R [n] and deliver data symbols affected by interference from subcarrier puncturing.

[0308] Fig.19 is an example of receiving DFT-s-OFDM symbols step 1802 (about Fig.18 1900. The process 1900 includes receiving a time domain receive waveform s from a channel 1902. R [n], CP removal (-CP) and serial / parallel conversion (S / P) in step 1904, N-point DFT (DFT N ), extraction of the M subcarriers allocated to the user (shown in brackets after step 1906), channel estimation in step 1908, equalization (Eq.) in step 1910, M-point inverse DFT (IDFTM) in step 1912, and) parallel / serial conversion (P / S) in step 1914. In some implementations, there may be further or different processing blocks.

[0309] Regarding the interference elimination step 1804 in some specific implementations (such as Fig.18 ), interference cancellation includes cancellation of interference introduced by the subcarrier puncturing process at the BS side. In some implementations, the WTRU may utilize the presence of a padding sequence, for example, to help estimate and / or further remove interference terms from time domain symbols prior to demodulation. In some implementations, any suitable detection strategy may be used, including successive interference cancellation (SIC), maximum likelihood (ML) detector, or others.

[0310] To illustrate this, follow the pattern Subcarrier puncturing and RS insertion of generate interference terms containing L periodic terms p[m] in the time domain, which are frequency shifted by p in the following expression:

[0311]

[0312] Here, m is the index of the sample in the time domain. In some implementations, the DFT of p[m] is equal to the value of the inserted RS symbol minus the punctured subcarrier. In some implementations, the receiver can therefore use this term to estimate the interference with the aid of the padding symbols c[m] appended to the data, after appropriately undoing the permutation step and the frequency shift p.

[0313] Regarding some specific implementation feedback reports 1810 (such as Fig.18), the feedback report to the BS may include a PSeqS report and / or a time domain report message.

[0314] In some embodiments, the WTRU may provide PSeqS reports to the BS on a periodic, semi-periodic, or on-demand basis, which may include, but are not limited to, any one or more of the following indications: a preferred padding sequence structure identifier (PSeqSID); mean square error (MSE) of interference estimation during the signal detection process; signal-to-noise ratio (SNR) after detection; advanced performance metrics before or after FEC, such as bit error rate (BER) or block error rate (BLER); and / or metrics related to the convergence of a successive interference cancellation (SIC) algorithm, such as the number of iterations or residual error.

[0315] In some implementations, for example, when more than one TRP has established a connection with the WTRU, multiple PSeqS reports may be independently transmitted by the WTRU to the multiple TRPs, where each report may include any or several of the above-mentioned indications to any TRP.

[0316] In some implementations, if the PSeqS report is transmitted by the WTRU, the PSeqS report may be updated according to a desired periodicity to follow the rate of change of the wireless channel and / or the change of the WTRU performance. In some implementations, the periodicity is sufficient to respond to the rate of change of the wireless channel and / or the WTRU performance. In some implementations, the PSeqS report may be transmitted to the BS, for example, via a MAC CE, but other possibilities are possible in other implementations.

[0317] In some implementations, the WTRU may also transmit a time domain report message to the BS, which may include time domain measurement results, for example, via a control channel or a data channel, for example, through UCI, or as part of the PUSCH. In some implementations, the WTRU may perform time domain measurements on the time domain signal resulting after equalization (e.g., by discarding all frequency subcarriers not allocated to the WTRU), such as the absolute magnitude of interference from RS puncturing / insertion, for example, in order to not be affected by the PAPR of signals for other users. In some implementations, the time domain measurements performed by the WTRU may also be performed after interference cancellation and discarding all frequency subcarriers not allocated to the WTRU, such as time domain autocorrelation. In some implementations, the number of symbols used for time domain measurements may be indicated by the WTRU in the time domain measurement configuration information using, for example, DCI or semi-periodic / periodic RRC configuration messages. In some implementations, the BS may also configure the timing of the time domain report message, such as through the time domain report configuration information in the DCI or the RRC time domain report configuration message.

[0318] In some implementations, considering the SIC algorithm described below with respect to simulations, the complexity in terms of complex multipliers of the detection process after the equalization step (e.g., as is common in the prior art) is given by the following equation:

[0319]

[0320] Here, N it is the number of SIC iterations, and f QAM (·) denotes a nonlinear function that assigns the constellation symbol closest to the input symbol as a function of length M. This is more complex than the solution described above regarding semi-static insertion of distributed RSs at the BS side without UE feedback and the solution described above regarding the interleaved RS insertion technique, but in some implementations, provides better control over PAPR and performance, as described below in the description of simulation results.

[0321] Some implementations involve dynamic insertion of distributed RSs by the WTRU based on configuration information from the BS.

[0322] Fig. 20 2000 is a flow chart illustrating an example process 2000 for dynamic RS insertion at the WTRU side. Fig. 20 In the example of FIG. 5 , the WTRU performs the following steps for dynamic insertion of a distributed RS:

[0323] In some implementations, the WTRU may select (e.g., dynamically select) one or more padding sequences in step 2002. In some implementations, the padding sequences are selected by the WTRU (e.g., based on PAPR measurements 2004 performed by the WTRU on the current symbol and / or several previous symbols, and / or based on configuration information received from the BS (e.g., in signaling 2006)) from a set of padding sequence structures specified in a predetermined codebook, which configuration information may include a set of padding sequences to be used and a set of conditions and associated sequences to be used by the WTRU (e.g., in RRC). In step 2008, the one or more padding sequences may be appended to the modulated data symbols.

[0324] In some implementations, in step 2010, a permutation is optionally applied to the resulting data block and padding symbols, for example in such a way that the complex modulation symbols after the permutation are uncorrelated and the permuted positions of the padding symbols are different from each other under modulo L.

[0325] In some implementations, an M-point DFT may be performed in step 2012. In some implementations, the subcarriers at the target pilot positions are punctured and replaced with M RS symbols (which may be complex-valued or blank). In some implementations, standard DFT-s-OFDM processing is then performed to generate a time domain waveform 2014, and PAPR measurements are performed by the WTRU 2004, for example, to refine padding sequence selection in subsequent time intervals.

[0326] In some implementations, the WTRU may optionally signal the one or more padding sequence structures used to the BS, for example, via one or more padding sequence structure identifier (PSeqSID) fields, which may be transmitted once during session establishment and / or dynamically updated during data transfer, or alternatively, the sequence identifier may be blindly detected by the BS without explicit signaling. In some implementations, for example, where the WTRU may send a data channel to multiple transmit / receive points (TRPs), the WTRU may transmit multiple PSeqS ID fields or a combined PSeqS ID field to one or more TRPs involved in the communication, the communication containing an indication of the one or more padding sequence structures used.

[0327] Fig.21 is an example of BS2102 and WTRU 2104 (in Fig.21 21) between the UE and the WTRU, including uplink data 2190, for example, for dynamic RS insertion at the WTRU side. In some implementations, the feedback loop 2100 illustrates the feedback loop with respect to Fig. 20 The steps shown correspond to those described.

[0328] In the feedback loop 2100, the WTRU 2104 may select one or more padding sequence structures to be used based on PAPR measurements performed by the WTRU 2104 and padding sequence selection configuration information 2130 received from the BS 2102, the padding sequence selection configuration information including, for example, a set of sequences to be used and a set of conditions and associated sequences to be used. In some implementations, these conditions may establish, for example, a set of metrics and associated thresholds that are designed to trigger different padding sequence structures by the WTRU 2104 under certain conditions. For example, in some implementations, a PAPR or BER threshold signaled by the BS may trigger the use of one padding sequence structure type or a set of padding sequence structure types if the PAPR or BER statistics calculated by the WTRU 2104 exceed the threshold. In some implementations, the criteria for selecting the padding sequence structure may be signaled by the BS, for example, via RRC signaling, and may also be updated by the gNB, for example, in a MAC CE, DCI, and / or RRC reconfiguration message.

[0329] In some implementations, the WTRU 2104 may optionally transmit control information about the used padding sequence structure to the BS 2102 with a periodicity given by the time stamp of the sequence selection procedure. In some implementations, the padding sequence structure identifier (PSeqS ID) field 2120 may be transmitted during session establishment, for example, once (e.g., a default one), as part of, for example, radio resource control (RRC) establishment, and / or may be dynamically updated during data transfer within uplink control information (UCI). In some implementations, the BS 2102 may also perform blind detection of the used padding sequence without explicit signaling.

[0330] In some implementations, the time scale for filling the sequence selection procedure may range from very long (connection-based) to very fast (symbol-based) and be adaptive. In some implementations, different time scales are allowed depending on the application and these time scales may be affected by the periodicity of the feedback reports transmitted by the WTRU 2104. In some implementations, the periodicity indicated by the PSeqS ID 2120 (if present) may be equal to the time scale for sequence selection (e.g., to provide a signaling indication with the same periodicity as the sequence selection procedure), for example, in such a way that a signaling procedure updated over a long period of time corresponds to a long time scale in the sequence selection procedure and vice versa. In some implementations, if blind detection is used on the BS 2102 side, the blind detection does not require any signaling of the PSeqS ID 2120 from the WTRU. For example, in some implementations, very long means, for example, on the order of minutes or hours, for example, as determined by the duration of the connected session. In some implementations, very fast means, for example, on the order of microseconds, for example, as determined by the duration of a symbol.

[0331] In cases where multiple transmit / receive points (TRPs) may establish wireless connections to the WTRU, in some embodiments, the WTRU 2104 may transmit multiple PSeqS ID 2120 fields or a combined PSeqS ID 2120 field (including an indication of the padding sequence structure used) to one or more TRPs, for example, via a single UCI, multiple UCIs associated with different TRP transmissions, or as part of a radio resource control (RRC) establishment, and / or dynamically updated during data transfer within the UCI.

[0332] In some implementations, the PAPR measurement may be performed by the WTRU 2104, for example, in a current symbol and / or several previous symbols. In some implementations, the number of symbols used for the PAPR measurement may be indicated by the BS 2102, for example, in the time domain measurement configuration 2132 information, for example, using a DCI or a semi-periodic / periodic RRC configuration message.

[0333] about Fig. 20 The remaining blocks shown and described may be similar to those described with respect to Fig.11 and Fig.17 Those blocks are shown and described, and relate to adding padding sequences to input data blocks, permutation to minimize high undesirable autocorrelation, transform precoding, subcarrier puncturing, insertion of RS symbols, generation of time domain signal waveforms, and PAPR measurements.

[0334] The techniques described herein for post-DFT insertion based on padding sequence adaptation are simulated for the case of DM-RS insertion in different time and frequency patterns. Figure 22 to Figure 27is a graph illustrating simulations and results compared with the case without pilot (L=0) but with interleaved RS insertion. Table 1 describes the values ​​assumed in the simulations.

[0335] Table 1 Simulation assumptions

[0336]

[0337]

[0338] (1) Scenario definition:

[0339] S1(constant envelope):

[0340] x[m]={d[0],…,d[ML-1],ZC[0],…,ZC[L-1]}

[0341] S2 (blank):

[0342] x[m]={d[0],…,d[ML-1],0,…,0}

[0343] S3 (Sign Reversal):

[0344] x[m]={d[0],…,d[ML-1],-d[0],…,-d[L-1]}

[0345] S4(Phase Shift):

[0346] x[m]={d[0],…,d[ML-1],e jπ / 2 d[0],…,e jπ / 2 d[L-1]}

[0347] S5 (interwoven):

[0348] Interleaved RS insertion with smaller DFT for comparison

[0349] (2) Pseudo code for SIC detection:

[0350]

[0351]

[0352] Fig. 22 and Fig.23 2200 and 2300 , respectively, which show simulated PAPR results and illustrate PAPR CCDF values ​​obtained using scenarios S1-S5. Fig. 22 is a line graph 2200 illustrating the PAPR for one DM-RS symbol. Fig.23is a line graph 2300 illustrating the PAPR for 4 DM-RS symbols. The PAPR increase is negligible for 1 DM-RS symbol and only has a 0.1 dB to 0.2 dB increase in QPSK for 4 DM-RS symbols compared to L=0. In 16 / 64QAM, the PAPR is within (-0.05, 0.05) dB of L=0. Although the PAPR is consistent with the case without pilots, different padding sequence structures produce different PAPR values.

[0353] Figure 24 to Figure 27 2400, 2500, 2600, and 2700, respectively, which show simulated BER results and illustrate the BER results obtained in scenarios S1 - S5. S1 has up to 2dB SNR increase compared to the no pilot case because the useful energy of the data is lower, while S3 produces the best performance. Fig.24 is a line graph 2400 illustrating the BER of one DM-RS symbol under AWGN conditions. Fig.25 is a line graph 2500 illustrating the BER of 4 DM-RS symbols under AWGN conditions. Fig.26 2600 is a line graph illustrating the BER of one DM-RS symbol under Rayleigh conditions. Fig. 27 is a line graph 2700 illustrating the BER of 4 DM-RS symbols under Rayleigh conditions.

[0354] The following description illustrates various exemplary implementations, including pre-DFT RS insertion based on IFDMA, post-DFT RS insertion based on padding sequence adaptation (with and without feedback), and data detection based on post-DFT RS insertion with padding sequence adaptation (with and without feedback).

[0355] Fig.28 is a flow chart illustrating an example process 2800 related to detection of a shared DFT-s-OFDM symbol with pre-DFT insertion of an IFDMA-based RS. In the example process 2800, a WTRU 2802 transmits a shared DFT-s-OFDM symbol between data and an RS. In step 2804, the WTRU 2802 obtains information about the characteristics of the inserted RS (e.g., the RS sequence to be used, its length, or the first subcarrier offset) in an RS configuration message.

[0356] In step 2806, the WTRU 2802 determines a first set of complex pilot symbols, for example, by performing one or more repetitions of the RS sequence. In step 2808, the WTRU 2802 generates a second set of complex pilot symbols, for example, by applying a first subcarrier offset to the first set of complex pilot symbols.

[0357] In step 2810, the WTRU 2802 generates a first set of complex data symbol groups, e.g., by dividing the complex modulated data symbols into one or more consecutive symbol groups. In step 2812, the WTRU 2802 generates a second set of complex data symbol groups, e.g., by performing one or more repetitions of each group of symbols in the first set of complex data symbol groups. In step 2814, the WTRU 2802 generates a third set of complex data symbol groups, e.g., by applying a second set of subcarrier offsets to the second set of complex data symbol groups.

[0358] In step 2816, the WTRU 2802 performs a DFT operation on the sum of the second set of complex pilot symbols and the third set of complex data symbols, for example, to determine a discrete frequency response on a set of subcarriers. In step 2818, the WTRU 2802 performs an IFFT on the set of subcarriers and transmits a DFT-s-OFDM symbol including data and RS.

[0359] In some implementations, the RS configuration message indicates any one of an RS sequence to be used, a first subcarrier offset, a number of allocated subcarriers M, and / or a number L of RS complex symbols contained in a shared DFT-s-OFDM symbol. In some implementations, the first subcarrier offset is an integer lower than (M / L) that represents the position of the subcarrier containing the RS symbol. In some implementations, the RS configuration message is received from a second WTRU or a set of second WTRUs via RRC signaling or through a DCI or MAC CE indication. In some implementations, the RS configuration message is obtained via an indication from a higher layer. In some implementations, the repetition of the RS sequence causes the L RS symbols to be repeated M / L times to generate a first set of complex pilot symbols. In some implementations, the division of the complex modulated data symbols is performed in such a way that the (ML) complex symbols are segmented into L consecutive groups of (ML) / L complex symbols, each group generating a first set of complex data symbol groups. In some implementations, the second set of subcarrier offsets includes non-repeating integer values ​​that are lower than L and different from the first subcarrier offsets. In some implementations, the complex modulated data symbols may undergo a permutation step before being divided into one or more consecutive symbol groups to minimize the maximum autocorrelation at times other than zero. In some implementations, the size of the DFT operation is the same as the number of subcarriers allocated to the WTRU in the DFT-s-OFDM symbol (including RS and data). In some implementations, the WTRU is a base station equipment in the downlink of a wireless communication system. In some implementations, the WTRU is a user equipment in the uplink of a wireless communication system. In some implementations, the WTRU is a user equipment in the sidelink of a wireless communication system.

[0360] Fig.29 29 is a flow chart illustrating an example process 2900 related to transmission of a shared DFT-s-OFDM symbol with post-DFT insertion of RS with no feedback based padding sequence adaptation. In the example process 2900, a first WTRU 2902 (or a set of first WTRUs) transmits a shared DFT-s-OFDM symbol between data and RS to a second WTRU (or a set of second WTRUs).

[0361] In step 2904, the WTRU 2902 obtains information about the characteristics of the inserted RS in the RS configuration message, such as the RS sequence to be used, its length, or the first subcarrier offset. In step 2906, the WTRU 2902 performs measurements (e.g., PAPR) on one or more generated signals, where in some implementations, the generated signals may be time domain signals including signals addressed to a second WTRU or a set of second WTRUs;

[0362] WTRU 2902 compares the measurement result (e.g., PAPR) with a first threshold value T1, and under condition 2908 that the measurement result exceeds the first threshold value T1, (e.g., PAPR>T1), WTRU 2902 updates one or more filling sequence structures from a filling sequence structure codebook based on the PAPR measurement result in step 2910, and then transmits to a second WTRU or a set of second WTRUs in step 2912, for example, signaling information about the one or more filling sequence structures used.

[0363] Otherwise, under condition 2908 that the measurement result does not exceed the first threshold T1, (e.g., PAPR!>T1), WTRU2902 transmits in step 2912 to a second WTRU or a set of second WTRUs, for example, signaling information about the one or more filling sequence structures used, without updating one or more filling sequence structures from a filling sequence structure codebook based on the PAPR measurement result.

[0364] In step 2914, the WTRU 2902 constructs a first set of symbols, for example, by appending one or more padding sequences to a second set of complex modulated data symbols in a DFT-s-OFDM symbol. In step 2916, the WTRU 2902 performs a DFT operation on the first set of symbols to determine a discrete frequency response on a first set of subcarriers. In step 2918, the WTRU 2902 punctures a subset of subcarriers and inserts complex RS symbols in the frequency domain at the locations of the punctured subcarriers to obtain a second set of subcarriers. In step 2920, the WTRU 2902 performs an IFFT on the second set of subcarriers and transmits a DFT-s-OFDM symbol including data and RS.

[0365] In some implementations, the RS configuration message includes any of an RS sequence to be used, a first subcarrier offset, a number of allocated subcarriers M, and / or a number of RS complex symbols L contained in a shared DFT-s-OFDM symbol. In some implementations, the first subcarrier offset is an integer lower than (M / L) that represents the position of the subcarrier containing the RS symbol. In some implementations, the RS configuration message is received from the second WTRU or set of second WTRUs via RRC signaling or through a DCI or MAC CE indication. In some implementations, the RS configuration message is received via a higher layer (e.g., RRC).

[0366] In some implementations, a padding sequence structure codebook may include a set of padding sequence structures known a priori to the first WTRU or a set of first WTRUs and the second WTRU or a set of second WTRUs. In some implementations, a PAPR measurement may be performed by the first WTRU or a set of first WTRUs on a time domain signal that includes all data and control information mapped to subcarriers assigned to the second WTRU at a current DFT-s-OFDM symbol. In some implementations, a PAPR measurement may be performed by the first WTRU or a set of first WTRUs on a time domain signal that is generated after discarding frequency subcarriers that are not assigned to the WTRU at the current DFT-s-OFDM symbol. In some implementations, a first threshold indicates a requirement to switch to another padding sequence structure with a lower PAPR. In some implementations, a number of padding sequences to be appended to a complex modulated data symbol is determined based on a frequency pattern of the RS symbol such that each appended padding sequence may be used to generate a set of RS subcarriers at periodic frequency locations with a periodicity equal to M / L. In some implementations, the length of the padding sequence structure can be the same as or different from the number of RS symbols to be inserted.

[0367] In some implementations, the selection of one or more filling sequence structures may be based on a priori known classification of filling sequence structures in terms of their PAPR and performance characteristics. In some implementations, the selection of one or more filling sequence structures may be based on PAPR measurements performed by the first WTRU or a set of WTRUs on one or several previous DFT-s-OFDM symbols. In some implementations, the selection of one or more filling sequence structures may be based on determining whether the PAPR measurement result is above or below a given threshold. In some implementations, the threshold may be set by the application or configured by a higher layer as a function of a predetermined policy or instantaneous cell conditions. In some implementations, the selection of one or more filling sequence structures may be based on the results of a machine learning (ML) algorithm trained to suggest an optimal filling sequence based on the measurement results. In some implementations, the selection of one or more filling sequence structures may be based on a set of sequences to be used and a set of conditions to be satisfied. In some implementations, the set of conditions may include a set of metrics and associated thresholds designed to trigger different filling sequence structures by the first WTRU or a set of first WTRUs under certain conditions. In some implementations, the condition set may be signaled by the second WTRU via RRC signaling and may be updated, for example, in a MAC CE, DCI and / or RRC reconfiguration message.

[0368] In some implementations, the signaling information to the second WTRU or set of second WTRUs may include a padding sequence structure indication within a default codebook of padding sequence structures that is known a priori to the first WTRU and the second WTRU. In some implementations, the padding sequence structure indication may be transmitted by the first WTRU or set of first WTRUs (via, for example, one or more padding sequence structure indications) via RRC signaling or via a DCI or MAC CE indication. In some implementations, a permutation may be applied to the M complex symbols after appending the one or more padding sequences in such a way that the permuted positions of the symbols of the padding sequences are different from each other under modulo L and the magnitude of the resulting autocorrelation is minimized at times other than zero. In some implementations, the size of the DFT operation is the same as the number of subcarriers allocated to the second WTRU in the DFT-s-OFDM symbol (including RS and data).

[0369] In some implementations, in a downlink of a wireless communication system, the first WTRU is a base station equipment and the second WTRU is a user equipment. In some implementations, the set of first WTRUs is a plurality of transmit-receive points in a downlink of a multi-TRP wireless communication system. In some implementations, the first WTRU and the second WTRU are user equipment in a side link of a wireless communication system. In some implementations, in an uplink of a wireless communication system, the first WTRU is a user equipment and the second WTRU is a base station equipment. In some implementations, the set of second WTRUs is a plurality of transmit-receive points in an uplink of a multi-TRP wireless communication system.

[0370] Fig.30 is a flow chart illustrating an example process 3000 related to transmission of a shared DFT-s-OFDM symbol with post-DFT insertion of RS based on padding sequence adaptation with feedback. In the example process 3000, a first WTRU 3000 (or a set of first WTRUs) transmits a shared DFT-s-OFDM symbol between data and RS (i.e., a symbol including both data and RS) to a second WTRU (or a set of second WTRUs).

[0371] In step 3004, the WTRU 3002 obtains information about the characteristics of the inserted RS in the RS configuration message, such as the RS sequence to be used, its length, or the first subcarrier offset. In step 3006, the WTRU 3002 receives feedback information from the second WTRU, such as a time domain report message and decoding performance, such as BLER.

[0372] Under condition 3008 that the feedback information includes a request to update the padding sequence structure, in step 3014, the WTRU 3002 selects one or more padding sequence structures from a subset of the padding sequence structure codebook characterized by a lower PAPR based on the PAPR measurement result or the feedback information being higher than the first threshold or the second threshold.

[0373] Otherwise, under condition 3008 that the feedback information does not include a request to update the padding sequence structure, the WTRU 3002 performs a measurement (e.g., PAPR) on one or more generated signals and compares the measurement result with a first threshold in step 3014, wherein the generated signal is a time domain signal including a signal addressed to a second WTRU or a set of second WTRUs. In step 3010, the WTRU 3002 also compares information from the time domain report message (e.g., maximum autocorrelation R) with a second threshold and compares the decoding performance (e.g., BLER) with a third threshold.

[0374] Under condition 3012 that the measurement result exceeds a first threshold (e.g., PAPR>T1) and / or the information exceeds a second threshold (e.g., R>T2) and / or the decoding performance exceeds a third threshold (e.g., BLER>T3), in step 3014, WTRU3002 selects one or more filling sequence structures from a subset of a filling sequence structure codebook characterized by a lower PAPR based on the PAPR measurement result or feedback information being higher than the first threshold or the second threshold, and / or selects one or more filling sequence structures from a subset of a filling sequence structure codebook characterized by a lower BLER based on the decoding performance being higher than the third threshold, and in step 3016, WTRU 3002 transmits signaling information to a second WTRU or a set of second WTRUs based on (e.g., indicating) the one or more filling sequence structures used.

[0375] Otherwise, under condition 3012 that the measurement result does not exceed a first threshold (e.g., PAPR!>T1) and the information does not exceed a second threshold (e.g., R!>T2) and the decoding performance does not exceed a third threshold (e.g., BLER!>T3), the WTRU 3002 transmits signaling information to a second WTRU or a set of second WTRUs based on (e.g., indicating) one or more filling sequence structures used (e.g., without reselecting a filling sequence structure).

[0376] In step 3018, the WTRU 3002 constructs a first set of symbols by appending one or more padding sequences to a second set of complex modulated data symbols in the DFT-s-OFDM symbol. In step 3020, the WTRU 3002 performs a DFT operation on the first set of symbols to determine a discrete frequency response on a first set of subcarriers. In step 3022, the WTRU 3002 punctures a subset of subcarriers and inserts complex RS symbols in the frequency domain at the locations of the punctured subcarriers to obtain a second set of subcarriers. In step 3024, the WTRU 3002 performs an IFFT on the second set of subcarriers and transmits a DFT-s-OFDM symbol including data and RS.

[0377] In some implementations, the RS configuration message includes any of an RS sequence to be used, a first subcarrier offset, a number of allocated subcarriers M, and / or a number of RS complex symbols L contained in a shared DFT-s-OFDM symbol. In some implementations, the first subcarrier offset is an integer lower than (M / L) that represents the position of the subcarrier containing the RS symbol. In some implementations, the RS configuration message is received via a higher layer (e.g., RRC). In some implementations, the padding sequence structure codebook may include a set of padding sequence structures that are a priori classified according to their PAPR and decoding performance characteristics and are known to the first WTRU or a set of first WTRUs and the second WTRU or a set of second WTRUs.

[0378] In some implementations, the feedback information may include, for example, one or more time domain report messages or one or more padding sequence structure reports transmitted by the second WTRU to the first WTRU or set of first WTRUs via, for example, a single or multiple report messages. In some implementations, the time domain report message may include a measurement of an absolute magnitude of interference on the signal generated after equalization performed by the second WTRU in one or more previous DFT-s-OFDM symbols and before interference cancellation. In some implementations, the time domain report message may include a measurement of a maximum autocorrelation of a complex modulation symbol after interference cancellation performed by the second WTRU in one or more previous DFT-s-OFDM symbols.

[0379] In some implementations, the fill sequence structure report may include any of a request to update the fill sequence structure, a preferred fill sequence structure, and decoding performance. In some implementations, the decoding performance may be based on error rate performance, such as BER / BLER, mean square error of interference estimation, post-detection signal-to-noise ratio, and / or any metric related to the performance of a successive interference cancellation technique performed by the second WTRU. In some implementations, the PAPR measurement may be performed by the first WTRU or a set of first WTRUs on a time domain signal containing all data and control information mapped to subcarriers allocated to the second WTRU at the current DFT-s-OFDM symbol.

[0380] In some implementations, the first threshold and the second threshold indicate a requirement to switch to another filling sequence structure with a lower PAPR. In some implementations, the third threshold indicates a requirement to switch to another filling sequence structure with better decoding performance (e.g., lower BLER). In some implementations, the number of filling sequences to be appended to the complex modulated data symbol is determined based on the frequency pattern of the RS symbol, for example, so that each additional filling sequence can be used to generate a set of RS subcarriers at a periodic frequency position with a periodicity equal to M / L. In some implementations, the length of the filling sequence structure may be the same as or different from the number of RS symbols to be inserted. In some implementations, the selection of one or more filling sequence structures may be based on determining whether the PAPR measurement result or the time domain report message received from the second WTRU is above a given threshold. In some implementations, the threshold may be set by the application or configured by a higher layer as a function of a predetermined policy or instantaneous cell condition.

[0381] In some implementations, the selection of one or more fill sequence structures may be based on the results of a machine learning (ML) algorithm trained to suggest an optimal fill sequence based on measurement results and feedback information from a second WTRU. In some implementations, the selection of one or more fill sequence structures may be triggered by an indication from a second WTRU or a set of second WTRUs to switch to another fill sequence structure. In some implementations, the selection of one or more fill sequence structures may be based on a set of sequences to be used and a set of conditions to be met. In some implementations, the set of conditions may include a set of metrics and associated thresholds designed to trigger different fill sequence structures by a first WTRU or a set of first WTRUs under certain conditions. In some implementations, the set of conditions may be signaled by the second WTRU via RRC signaling and may be updated, for example, in a MAC CE, DCI, and / or RRC reconfiguration message.

[0382] In some implementations, the signaling information to the second WTRU or set of second WTRUs may include a padding sequence structure indication within a default codebook of padding sequence structures that is known a priori to the first WTRU and the second WTRU. In some implementations, the padding sequence structure indication may be transmitted by the first WTRU or set of first WTRUs (via, for example, one or more padding sequence structure indications) via RRC signaling or via a DCI or MAC CE indication. In some implementations, the padding sequence structure report and the time domain report message may be received by the first WTRU or set of first WTRUs in a periodic, semi-periodic, on-demand, or event-based manner via a control channel or a data channel (e.g., via UCI, MAC CE, or as part of PUSCH). In some implementations, the periodic and semi-persistent reports may be configured by the first WTRU via higher layer signaling to use control uplink shared resources, for example, via PUCCH. In some embodiments, the periodic and semi-persistent reporting may be configured to use data uplink shared resources, for example, via PUSCH, using a new WTRU identifier (e.g., X-RNTI) on a unique or group basis to decode the DCI containing the reporting configuration.

[0383] In some implementations, the semi-persistent reporting may be configured with a report set and a DL MAC CE or DCI activating / deactivating one of the reports in the configured set. In some implementations, the on-demand reporting may include a MAC CE or DCI message requesting the second WTRU to transmit a report with the next available PUCCH resources. In some implementations, the on-demand reporting may be configured with uplink resources on PUSCH or allocated uplink resources on PUSCH by request of the second WTRU, using a new UE identity (e.g., X-RNTI) on a unique or group basis, for example, to decode the DCI containing the reporting configuration. In some implementations, the event-based reporting may be based on a threshold or number of receptions or duration (e.g., trigger time) to be used for making measurements, so that a feedback report is transmitted when an event is triggered (e.g., when a measurement result or a set of measurement results is below / above the threshold). In some implementations, the event-based reporting may be received from the second WTRU via a UL MAC CE, RRC, or UCI message.

[0384] In some implementations, a permutation may be applied to the M complex symbols after appending one or more padding sequences, for example in such a way that the permuted positions of the symbols of the padding sequences are different from each other under modulo L and / or the maximum magnitude of the autocorrelation is minimized at times other than zero. In some implementations, the size of the DFT operation is the same as the number of subcarriers allocated to the second WTRU in the DFT-s-OFDM symbol (including RS and data). In some implementations, in a downlink of a wireless communication system, the first WTRU is a base station equipment and the second WTRU is a user equipment. In some implementations, the set of first WTRUs is a plurality of transmit / receive points in a downlink of a multi-TRP wireless communication system. In some implementations, the first WTRU and the second WTRU are user equipment in a side link of a wireless communication system.

[0385] Some implementations involve data detection based on post-DFT RS insertion with padding sequence adaptation (eg, with and without feedback).

[0386] For example, Fig.31 is a flow chart illustrating an example process 3100 related to detection of shared DFT-s-OFDM symbols with post-DFT insertion of RSs with no feedback based padding sequence adaptation. In the example process 3100, a first WTRU (or set of WTRUs) receives a shared DFT-s-OFDM symbol between data and RSs from a second WTRU (or set of second WTRUs).

[0387] In step 3104, the WTRU 3102 obtains information about the characteristics of the inserted RS in the RS configuration message (e.g., the RS sequence to be used, its length, or the first subcarrier offset). In step 3106, the WTRU 3102 determines a padding sequence structure indication (e.g., by, for example, DCI in a PDCCH message, determining the padding sequence structure indication from a codebook based on the received indication; receiving a DFT-s-OFDM symbol including data and RS). In step 3108, the WTRU 3102 receives the DFT-s-OFDM symbol including data and RS. In step 3110, the WTRU 3102 cancels interference from subcarrier puncturing and RS insertion (e.g., based on the determined padding sequence structure).

[0388] In some implementations, the RS configuration message includes any one of an RS sequence to be used, a first subcarrier offset, a number of allocated subcarriers M, or a number of RS complex symbols L contained in a shared DFT-s-OFDM symbol. In some implementations, the first subcarrier offset is an integer lower than (M / L) that represents the position of the subcarrier containing the RS symbol. In some implementations, the RS configuration message is received from the second WTRU or set of second WTRUs via RRC signaling or through a DCI or MAC CE indication. In some implementations, the RS configuration message is received via a higher layer (e.g., RRC).

[0389] In some implementations, any of the initial / first padding sequence structure indication and the padding sequence structure codebook may be determined based on dedicated RRC information or by default through system information. In some implementations, the padding sequence structure indication may be periodically received from a second WTRU or a set of second WTRUs (e.g., through one or more padding sequence structure indications) via RRC signaling or through a DCI or MAC CE indication. In some implementations, the padding sequence structure indication may be periodically received from a second WTRU via RRC signaling or through a UCI or MAC CE indication. In some implementations, the determination of the padding sequence structure may be based on blind detection and an indication of a subset of one or more padding sequence structures in a default padding sequence structure codebook.

[0390] In some implementations, in a downlink of a wireless communication system, the first WTRU is a user equipment and the second WTRU is a base station equipment. In some implementations, the set of the second WTRU is a plurality of transmit-receive points in a downlink of a multi-TRP wireless communication system. In some implementations, the first WTRU and the second WTRU are user equipment in a side link of a wireless communication system. In some implementations, in an uplink of a wireless communication system, the first WTRU is a base station equipment and the second WTRU is a user equipment. In some implementations, the set of the first WTRU is a plurality of transmit-receive points in an uplink of a multi-TRP wireless communication system.

[0391] Fig.32 is a flow chart illustrating an example implementation 3200 related to detection of shared DFT-s-OFDM symbols with post-DFT insertion of RS based on padding sequence adaptation with feedback. Fig.32 In the example of , a first WTRU 3202 (or a set of WTRUs) receives a shared DFT-s-OFDM symbol between data and RS from a second WTRU or a set of second WTRUs.

[0392] In step 3204, the WTRU 3202 obtains information about the characteristics of the inserted RS in the RS configuration message (e.g., the RS sequence to be used, its length, or the first subcarrier offset). In step 3206, the WTRU 3202 determines 3206 a padding sequence structure indication from the codebook (e.g., based on the received indication via, for example, DCI in a PDCCH message). In step 3208, the WTRU 3202 receives a DFT-s-OFDM symbol including data and RS and determines a quality indication. In step 3210, the WTRU 3202 cancels interference caused by the RS insertion (e.g., based on the determined padding sequence structure).

[0393] In step 3214, under the condition 3212 that the quality indication is above the first threshold (e.g., Qual>T1), the WTRU 3202 performs a time domain measurement of the maximum autocorrelation of the received signal, or in step 3216, under the condition 3212 that the quality indication is not above the first threshold (e.g., Qual!>T1), the WTRU 3202 performs a time domain estimation of the absolute magnitude of interference on the received signal. In step 3218, the WTRU 3202 determines the decoding performance (e.g., BLER).

[0394] In step 3222, under condition 3220 that the maximum autocorrelation is higher than a second threshold (e.g., R>T2) and / or the interference is higher than a third threshold (I>T3), the WTRU 3202 selects a codebook subset with a lower PAPR, and / or under condition 3220 that the decoding performance is higher than a fourth threshold (e.g., BLER>T4), selects a codebook subset with a lower BLER, and sends feedback information (e.g., a time domain report message or a padding sequence structure report).

[0395] Otherwise, under condition 3220 that the maximum autocorrelation is not higher than the second threshold (e.g., R!>T2), the interference is not higher than the third threshold (I!>T3), and the decoding performance is not higher than the fourth threshold (e.g., BLER>T4), the process 3200 returns to step 3204, where the WTRU 3202 obtains information about the characteristics of the inserted RS (e.g., the RS sequence to be used, its length, or the first subcarrier offset) in the RS configuration message.

[0396] In some implementations, the RS configuration message includes any one of an RS sequence to be used, a first subcarrier offset, a number of allocated subcarriers M, and / or a number of RS complex symbols L contained in a shared DFT-s-OFDM symbol. In some implementations, the first subcarrier offset is an integer lower than (M / L) that indicates the position of the subcarrier containing the RS symbol. In some implementations, the RS configuration message is received from the second WTRU or a set of second WTRUs via RRC signaling or through a DCI or MAC CE indication. In some implementations, any one of the initial / first padding sequence structure indication and the padding sequence structure codebook may be determined by default based on dedicated RRC information or through system information.

[0397] In some implementations, a padding sequence structure indication may be periodically received from a second WTRU or a set of second WTRUs (via, for example, one or more padding sequence structure indications) via RRC signaling or via a DCI or MAC CE indication. In some implementations, the determination of the padding sequence structure may be based on blind detection and an indication of a subset of one or more padding sequence structures in a default padding sequence structure codebook. In some implementations, the quality measurement may include a signal-to-noise ratio measurement before or after detection. In some implementations, a time domain measurement of maximum autocorrelation and an absolute magnitude of interference may be performed by the first WTRU after equalization and interference cancellation. In some implementations, the time domain measurement may be performed on multiple DFT-s-OFDM symbols based on time domain measurement configuration information received, for example, via a DCI or a semi-periodic or periodic RRC configuration message. In some implementations, the time domain measurement may be sent in a time domain report message in a periodic, semi-persistent, on-demand, or event-based manner, where the periodicity is given, for example, by time domain report configuration information received in a DCI or an RRC time domain report configuration message.

[0398] In some implementations, the second threshold and the third threshold indicate a requirement to send feedback information including a request to the second WTRU or a set of second WTRUs to switch to another padding sequence structure with a lower PAPR. In some implementations, the fourth threshold indicates a requirement to send feedback information including a request to the second WTRU or a set of second WTRUs to switch to another padding sequence structure with better decoding performance (e.g., lower BLER). In some implementations, the decoding performance may be based on error rate performance, such as BER / BLER, mean square error of interference estimation, post-detection signal-to-noise ratio, or any metric related to the performance of a successive interference cancellation technique performed at the first WTRU. In some implementations, the DFT-s-OFDM symbol is received by performing an inverse DFT operation on the discrete frequency content of the signal. In some implementations, the size of the inverse DFT operation is the same as the number of subcarriers allocated to the second WTRU in the DFT-s-OFDM symbol (including RS and data).

[0399] In some implementations, an inverse permutation may be applied to the M complex symbols prior to said cancellation of interference to restore the original symbol positions after appending one or more padding sequences. In some implementations, the feedback information may include, for example, one or more time domain report messages or one or more padding sequence structure reports. In some implementations, the time domain report message may include a measurement of interference, or a measurement of a maximum autocorrelation at a time other than zero. In some implementations, the padding sequence structure report may include any of a request to update a padding sequence structure, a preferred padding sequence structure, and decoding performance. In some implementations, the padding sequence structure report may be transmitted to the second WTRU or a set of second WTRUs via, for example, a single or multiple padding sequence structure reports. In some implementations, the feedback information may be transmitted to the second WTRU or a set of second WTRUs via a control channel or a data channel (e.g., via a UCI, a MAC CE, or as part of a PUSCH) in a periodic, semi-periodic, on-demand, or event-based manner.

[0400] In some implementations, the periodic and semi-persistent reporting may be configured by the second WTRU via higher layer signaling to use control uplink shared resources, for example, via PUCCH. In some implementations, the periodic and semi-persistent reporting may be configured to use data uplink shared resources, for example, via PUSCH, using a new UE identity (e.g., X-RNTI), for example, on a unique or group basis, to decode the DCI containing the report configuration. In some implementations, the semi-persistent reporting may be configured with a report set and a DL MAC CE or DCI that activates / deactivates one of the reports in the configured set. In some implementations, the on-demand reporting may include a MAC CE or DCI message that requests the first WTRU to transmit a report with the next available PUCCH resources. In some implementations, the on-demand reporting may be configured with uplink resources on PUSCH, or allocated uplink resources on PUSCH by request of the first WTRU, and using a new UE identity (e.g., X-RNTI), for example, on a unique or group basis, to decode the DCI containing the report configuration.

[0401] In some implementations, the event-based report may be based on a threshold or number of receptions or duration (e.g., trigger time) to be used for measurement so that a feedback report is transmitted when an event is triggered (e.g., when a measurement result or a set of measurement results is below / above the threshold). In some implementations, the event-based report may be transmitted to the second WTRU via a UL MAC CE, RRC, or UCI message. In some implementations, in a downlink of a wireless communication system, the first WTRU is a user equipment and the second WTRU is a base station equipment. In some implementations, the set of second WTRUs is a plurality of transmit / receive points in a downlink of a multi-TRP wireless communication system. In some implementations, the first WTRU and the second WTRU are user equipment in a side link of a wireless communication system.

[0402] Fig.33 is a flow chart illustrating an example simplified process 3300 for detection of shared DFT-s-OFDM symbols with post-DFT insertion of RS based on padding sequence adaptation with feedback. In process 3300, a WTRU 3302 (or a set of WTRUs) receives a shared DFT-s-OFDM symbol between data and RS from a second WTRU (or a set of second WTRUs).

[0403] In step 3304, the WTRU 3302 obtains information about the characteristics of the inserted RS in the RS configuration message (e.g., the RS sequence to be used, its length and / or the first subcarrier offset). In step 3306, the WTRU 3302 determines the padding sequence structure from the codebook (e.g., based on the received indication via, for example, DCI in a PDCCH message). In step 3308, the WTRU 3302 receives the DFT-s-OFDM symbol including the data and the RS and determines that the quality measurement result (Qual) is below a first threshold T1. In step 3310, the WTRU 3302 performs a time domain measurement of interference on the received signal (e.g., based on the quality indication being below the first threshold) and cancels the interference caused by the RS insertion (e.g., based on the determined padding sequence structure). In step 3312, the WTRU 3302 estimates the absolute magnitude of the interference (I) from the RS insertion. In step 3314, the WTRU 3302 determines or obtains measurements of decoding performance (eg, BLER).

[0404] Under condition 3316 that an event (E) occurs (e.g., the interference power (I) is higher than the second threshold T2 and the decoding performance (BLER) is higher than the third threshold T3), in step 3318, the WTRU3302 selects a codebook subset with a lower BLER at the lowest possible PAPR based on the detected event (E) and sends feedback information (e.g., a time domain report message or a padding sequence structure report).

[0405] Otherwise, under condition 3316 that event (E) does not occur (e.g., the interference power (I) is not higher than the second threshold T2 or the decoding performance (BLER) is not higher than the third threshold T3), the process 3300 returns to step 3304, where the WTRU 3302 obtains information about the characteristics of the inserted RS in the RS configuration message (e.g., the RS sequence to be used, its length and / or first subcarrier offset).

[0406] In some implementations, the RS configuration message includes any one of an RS sequence to be used, a first subcarrier offset, a number of allocated subcarriers M, and / or a number of RS complex symbols L contained in a shared DFT-s-OFDM symbol. In some implementations, the first subcarrier offset is an integer lower than (M / L) that indicates the position of the subcarrier containing the RS symbol. In some implementations, the RS configuration message is received from the second WTRU or set of second WTRUs via RRC signaling or through a DCI or MAC CE indication.

[0407] In some implementations, any of the initial / first padding sequence structure indication and the padding sequence structure codebook may be determined based on dedicated RRC information or by default through system information. In some implementations, the padding sequence structure indication may be periodically received from the second WTRU or set of second WTRUs (via, for example, one or more padding sequence structure indications) via RRC signaling or through DCI or MAC CE indications. In some implementations, the determination of the padding sequence structure may be based on blind detection and an indication of a subset of one or more padding sequence structures in a default padding sequence structure codebook.

[0408] In some implementations, the quality measurement may include a signal-to-noise ratio measurement before or after detection. In some implementations, the estimation of the absolute magnitude of the interference may be performed by the first WTRU on a time domain signal produced after equalization and interference cancellation. In some implementations, the estimation of the absolute magnitude of the interference may be performed on multiple DFT-s-OFDM symbols based on time domain measurement configuration information received through, for example, a DCI or a semi-periodic or periodic RRC configuration message. In some implementations, the estimation of the absolute magnitude of the interference may be sent in a time domain report message in an event-based manner based on time domain reporting configuration information received in a DCI or RRC time domain reporting configuration message.

[0409] In some implementations, the feedback triggering event includes a second threshold value related to an absolute magnitude of interference, the second threshold value indicating a requirement to send feedback information including a request to the second WTRU or a set of second WTRUs to switch to another padding sequence structure with a lower PAPR. In some implementations, the feedback triggering event includes a third threshold value related to decoding performance, the third threshold value indicating a requirement to send feedback information including a request to the second WTRU or a set of second WTRUs to switch to another padding sequence structure with better decoding performance (e.g., lower BLER). In some implementations, the feedback triggering event includes a second threshold value and a third threshold value related to interference and decoding performance, respectively, the second threshold value and the third threshold value indicating a requirement to send feedback information including a request to the second WTRU or a set of second WTRUs to switch to another padding sequence structure with either a lower PAPR or a lower BLER.

[0410] In some implementations, the decoding performance may be based on error rate performance, such as BER / BLER, mean square error of interference estimation, post-detection signal-to-noise ratio, or any metric related to the performance of a successive interference cancellation technique performed at the first WTRU. In some implementations, the DFT-s-OFDM symbol is received by performing an inverse DFT operation on the discrete frequency content of the signal. In some implementations, the size of the inverse DFT operation is the same as the number of subcarriers allocated to the second WTRU in the DFT-s-OFDM symbol (including RS and data).

[0411] In some implementations, an inverse permutation may be applied to the M complex symbols prior to said elimination of interference to restore the original symbol positions after appending one or more padding sequences. In some implementations, the feedback information may include, for example, one or more time domain report messages or one or more padding sequence structure reports. In some implementations, the time domain report message may include a measurement result of the absolute magnitude of the interference caused by subcarrier puncturing and RS insertion. In some implementations, the padding sequence structure report may include any of a request to update the padding sequence structure, a preferred padding sequence structure, and decoding performance. In some implementations, the padding sequence structure report may be transmitted to the second WTRU or a set of second WTRUs via, for example, a single or multiple padding sequence structure reports.

[0412] In some implementations, the feedback information may be transmitted to the second WTRU or a set of second WTRUs via a control channel or a data channel (e.g., via UCI, MAC CE, or as part of PUSCH) based on the occurrence of an event. In some implementations, the event-based report may be transmitted to the second WTRU via a UL MAC CE, RRC, or UCI message. In some implementations, in the downlink of a wireless communication system, the first WTRU is a user equipment and the second WTRU is a base station equipment. In some implementations, the set of second WTRUs is a plurality of transmit / receive points in the downlink of a multi-TRP wireless communication system. In some implementations, the first WTRU and the second WTRU are user equipment in a side link of a wireless communication system.

[0413] Although features and elements are described above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method for receiving data via a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) waveform, the method comprising: receiving a reference signal (RS) configuration message; determining a padding sequence structure based on the received indication; Receive DFT-s-OFDM symbols; as well as Interference is eliminated based on the padding sequence structure. 2 . The method of claim 1 , wherein the filling sequence structure comprises at least one of the following: a constant envelope sequence, a sign-reversed data symbol, a phase-shifted data symbol, or a blank symbol. 3 . The method according to claim 1 , wherein the RS configuration message includes an RS sequence, an RS length and / or a subcarrier offset.

4. The method of claim 1, wherein the RS configuration message is received in at least one of: downlink control information (DCI), a medium access control (MAC) control element (CE), or a radio resource control (RRC) message. The method of claim 1 , wherein the received indication comprises a padding sequence structure identifier or a codebook index.

6. The method of claim 1, wherein the received indication is received in at least one of: downlink control information (DCI), a medium access control (MAC) control element (CE), or a radio resource control (RRC) message. The method according to claim 1 , wherein the padding sequence structure is estimated by blind detection based on the received indication.

8. The method of claim 1, wherein canceling the interference comprises canceling the interference from the DFT-s-OFDM symbol based on the padding sequence structure.

9. The method of claim 1 , wherein canceling the interference based on the padding sequence structure comprises: Interference caused by inserting the RS into the DFT-s-OFDM symbol is eliminated.

10. The method of claim 1, wherein canceling the interference based on the padding sequence structure comprises canceling the interference from the DFT-s-OFDM symbol prior to demodulation.

11. The method of claim 1 , further comprising sending feedback based on the elimination of the interference, wherein the feedback comprises at least one of: an indication of the performance of the elimination of the interference; an indication of a preferred padding sequence structure; or an indication of a bit error rate (BER) or an indication of a block error rate (BLER).

12. A wireless transmit receive unit (WTRU) configured to receive data via a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) waveform, the WTRU comprising: Circuitry configured to receive a reference signal (RS) configuration message; circuitry configured to determine a fill sequence structure based on the received indication; Circuitry configured to receive a DFT-s-OFDM symbol; and Circuitry is configured to cancel interference based on the padding sequence structure.

13. The WTRU of claim 12, wherein the padding sequence structure comprises, for example, at least one of: a constant envelope sequence, a sign-reversed data symbol, a phase-shifted data symbol, or a blank symbol.

14. The WTRU of claim 12, wherein the RS configuration message comprises at least one of: an RS sequence, an RS length, or a subcarrier offset.

15. The WTRU of claim 12, further comprising a circuit configured to receive the RS configuration message from at least one of: a downlink control information (DCI), a medium access control (MAC) control element (CE), or a radio resource control (RRC) message.

16. The WTRU of claim 12, wherein the received indication comprises a padding sequence structure identifier or a codebook index.

17. The WTRU of claim 12, further comprising a circuit configured to receive the indication from at least one of: a downlink control information (DCI), a medium access control (MAC) control element (CE), or a radio resource control (RRC) message.

18. The WTRU of claim 12, further comprising circuitry configured to estimate the padding sequence structure by blind detection based on the received indication.

19. The WTRU of claim 12, further comprising circuitry configured to cancel the interference from the DFT-s-OFDM symbol based on the padding sequence structure.

20. The WTRU of claim 12, further comprising circuitry configured to cancel interference caused by inserting the RS into the DFT-s-OFDM symbol.

21. The WTRU of claim 12, further comprising circuitry configured to cancel the interference from the DFT-s-OFDM symbol prior to demodulation.

22. The WTRU of claim 12, wherein the WTRU further comprises a circuit configured to send feedback based on the elimination of the interference, wherein the feedback comprises at least one of: an indication of the performance of the elimination of the interference; an indication of a preferred padding sequence structure; or an indication of a bit error rate (BER) or an indication of a block error rate (BLER).

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