WO2018085561A1 - Dtf-s-ofdm and ofdm with frequency domain cyclic prefix and cyclic suffix - Google Patents

Abstract

Techniques, methods, procedures and apparatuses may be used involving frequency domain cyclic prefix (CP) and cyclic suffix (CS) for Orthogonal Frequency Domain Modulation (OFDM) and Discrete Fourier Transform-spread OFDM (DFT-s-OFDM) processing and transmission. A wireless transmit/receive unit (WTRU) may generate a frequency domain (FD) cyclic suffix (CS) based on a replication of a header of a data block. The WTRU may also generate an FD cyclic prefix (CP) based on a replication of a tail of the data block. The WTRU may then prepend the FD CP to the data block and append the FD CS to the data block. Accordingly, the WTRU may map the FD CP, the data block and the FD CS to corresponding inputs of an IDFT block. Then, the WTRU may transmit the FD CP, the data block and the FD CS.

Description

DTF-S-OFDM AND OFDM WITH FREQUENCY DOMAIN CYCLIC PREFIX AND CYCLIC SUFFIX

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 62/416,539 filed November 2, 2016 and U.S. Provisional Application Serial No. 62/518,780 filed June 13, 2017, the contents of which are hereby incorporated by reference herein.

BACKGROUND

[0002] In long term evolution (LTE) wireless communications systems, orthogonal frequency division multiplexing (OFDM) may be used for downlink (DL) transmission while discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) may be used for uplink (UL) transmission. In conventional Cyclic Prefix (CP) DFT-s-OFDM, sometimes referred to as single carrier frequency division multiple access (SC-FDMA), the data symbols may be first spread with a discrete Fourier transform (DFT) block, and then may be mapped to the corresponding inputs of an inverse DFT (IDFT) block. The CP may be prepended to the beginning of the symbol in time in order to avoid inter- symbol interference (ISI) and may allow one-tap frequency domain equalization (FDE) at the receiver. Similarly, unique word (UW) DFT-s-OFDM may allow one-tap FDE by using a fixed sequence from the previous symbol's tail.

[0003] A transmitted waveform may be exposed to non-linear distortions due to non-ideal hardware characteristics in a communications link. Specifically, the impact of the non-ideal device characteristics may become more apparent at higher operating frequencies, for example, millimeter wave (mmW) or TeraHertz frequencies, and may cause more degradation of the link performance as compared to the those in traditional cellular frequencies. A possible impairment may be phase noise (PN), which may be magnified by the operating frequency of the communication link. Therefore, the Third Generation Partnership Project (3GPP) and Institute for Electrical and Electronic Engineers (IEEE) links operating at higher frequencies may be more susceptible to impairment than the links operating at lower frequencies, for example, below 6 gigahertz (GHz). Such higher operating frequencies may be used in, for example, fifth generation (5G) New Radio (NR) and IEEE 802.11 ad/ay wireless communications systems.

SUMMARY

[0004] Techniques, methods, procedures and apparatuses to reduce phase noise (PN) may be used involving a frequency domain (FD) cyclic prefix (CP) and an FD cyclic suffix (CS) for orthogonal frequency division multiplexing (OFDM) and discrete Fourier transform spread OFDM (DFT-s-OFDM) processing and transmission. A wireless transmit/receive unit (WTRU) may generate an FD CS based on a replication of a header of a data block. The WTRU may also generate an FD CP based on a replication of a tail of the data block. The WTRU may then prepend the FD CP to the data block and append the FD CS to the data block. Accordingly, the WTRU may map the FD CP, the data block and the FD CS to corresponding inputs of an inverse discrete Fourier transform (IDFT) block. Then, the WTRU may transmit the FD CP, the data block and the FD CS.

[0005] In an example, the WTRU may spread data symbols of the data block using a discrete

Fourier transform (DFT) operation. In a further example, the FD CP, the data block and the FD CS may be transmitted as one or more DFT-s-OFDM symbols. In another example, the FD CP, the data block and the FD CS are transmitted as one or more OFDM symbols. In an additional example, the FD CP, the data block and the FD CS may be transmitted as part of a hybrid DFT-s-OFDM and OFDM transmission. In still another example, the WTRU may transmit one or more reference symbols (RSs), wherein the power level of the RSs is adjusted. In yet another example, the WTRU may transmit one or more demodulation RSs, wherein each demodulation RS is part of a unique word (UW).

[0006] Also, a WTRU may receive an FD CS, a data block and an FD CP. Then the WTRU may discard the FD CS and FD CP from the data block. Further, the WTRU may process the data block using single-tap time domain equalization including point-to-point multiplication. The WTRU may then demodulate the processed data block.

[0007] In a further example, the FD CP, the data block and the FD CS may be received as one or more DFT-s-OFDM symbols. In another example, the FD CP, the data block and the FD CS may be received as one or more OFDM symbols. In an additional example, the data block and the FD CS may be received as part of a hybrid DFT-s-OFDM and OFDM transmission. Moreover, the WTRU may further receive one or more demodulation RSs, wherein each demodulation RS is part of a UW.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein:

[0009] FIG. 1 A is a system diagram of an example communications system in which one or more disclosed embodiments may be implemented;

[0010] FIG. 1 B is a system diagram of an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A;

[0011] FIG. 1 C is a system diagram of an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1 A;

[0012] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1A; [0013] FIG. 2 is a block diagram of an example of the impact of phase noise (PN) in the frequency domain with discrete Fourier transform spread orthogonal frequency division multiplexing (DFT- s-OFDM);

[0014] FIG. 3A is a block diagram of an example transmitter (Tx) for DFT-s-OFDM transmission;

[0015] FIG. 3B is a block diagrams of an example receiver (Rx) for DFT-s-OFDM using PN correction;

[0016] FIG. 4 is a signal diagram in frequency of an example of the impact of PN on data symbols;

[0017] FIG. 5A is a block diagram of an example frequency domain (FD) cyclic prefix (CP) and cyclic suffix (CS) for DFT-s-OFDM;

[0018] FIG. 5B is a block diagram of an example FD CP and CS for orthogonal frequency division multiplexing (OFDM);

[0019] FIG. 5C is a flow diagram of an example of generating an example FD CP and CS;

[0020] FIG. 5D is a block diagram of an example of receiving FD CP and CS for DFT-s-OFDM;

[0021] FIG. 5E is a block diagram of an example of receiving FD CP and CS for OFDM;

[0022] FIGS. 6A and 6B are signal diagrams in frequency of examples of the impact of PN on data symbols with CP and CS;

[0023] FIG. 7 is a block diagram of an example FD CS and CP for DFT-s-OFDM with two

WTRUs;

[0024] FIG. 8 is a block diagram of an example FD CS and CP for OFDM with two WTRUs;

[0025] FIGS. 9A and 9B are block diagrams of an example FD CS and CP for multiple data allocations;

[0026] FIG. 10 is a block diagram of an example reference symbol (RS) transmission with FD CP and CS;

[0027] FIG. 11 is a block diagram of an example exploitation of diagonalized PN structure with differential modulations;

[0028] FIG. 12 is a block diagram of an example exploitation of unique word (UW) DFT-s-OFDM for differential modulations;

[0029] FIG. 13 is a block diagram of an example hybrid utilization of differential modulation and quadrature amplitude modulation (QAM);

[0030] FIG. 14A, 14B and 14C are block diagrams of example methods for frequency thinning;

[0031] FIG. 15 is a block diagram of example methods for frequency thinning for UW DFT-s-

OFDM; and

[0032] FIG. 16 is a block diagram of example methods for frequency thinning and RS insertion after inverse discrete Fourier transform (IDFT). DETAILED DESCRIPTION

[0033] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word discrete Fourier transform spread orthogonal frequency division multiplexing (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0034] As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units ( TRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104/113, a core network (CN) 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a station (STA), may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head- mounted display (HMD), a vehicle, a drone, a medical device and applications (for example, remote surgery), an industrial device and applications (for example, a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0035] The communications systems 100 may also include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode-B, a Home Node B, a Home eNode-B, a next generation (gNB), a new radio (NR) NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

[0036] The base station 114a may be part of the RAN 104/113, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

[0037] 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 (for example, 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).

[0038] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104/113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed Uplink (UL) Packet Access (HSUPA).

[0039] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE- Advanced Pro (LTE-A Pro).

[0040] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using NR. [0041] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (for example, a eNB and a gNB).

[0042] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as Institute for Electrical and Electronic Engineers (IEEE) 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0043] The base station 114b in FIG. 1A may be a wireless router, Home Node B, Home eNode-

B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (for example, for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (for example, WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1 A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106/115.

[0044] The RAN 104/113 may be in communication with the CN 106/115, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or the CN 106/115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113, which may be utilizing a NR radio technology, the CN 106/115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0045] The CN 106/115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or the other networks 112. The PSTN 108 may include circuit- switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and/or the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104/113 or a different RAT.

[0046] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (for example, the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with 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.

[0047] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the

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

[0048] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Array (FPGA) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0049] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (for example, the base station 114a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0050] Although the transmit/receive element 122 is depicted in FIG. 1 B as a single element, the

WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (for example, multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0051] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0052] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (for example, a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0053] The processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (for example, nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0054] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (for example, longitude and latitude) regarding the current location of the

WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (for example, base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0055] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and/or Augmented Reality (VR/AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors. The sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor and the like.

[0056] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (for example, associated with particular subframes for both the UL (for example, for transmission) and DL (for example, for reception) may be concurrent and/or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self- interference via either hardware (for example, a choke) or signal processing via a processor (for example, a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (for example, associated with particular subframes for either the UL (for example, for transmission) or the DL (for example, for reception)).

[0057] FIG. 1 C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0058] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a. [0059] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0060] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0061] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN

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

[0062] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN

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

[0063] 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.

[0064] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (for example, an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0065] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (for example, temporarily or permanently) wired communication interfaces with the communication network.

[0066] In representative embodiments, the other network 112 may be a WLAN. [0067] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more STAs associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and/or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (for example, directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (for example, all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an ad-hoc mode of communication.

[0068] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (for example, 20 megahertz (MHz) wide bandwidth) or a dynamically set width, set via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (for example, every STA), including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off. One STA (for example, only one station) may transmit at any given time in a given BSS.

[0069] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0070] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and/or 160

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

[0071] Sub 1 gigahertz (GHz) modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11 ah relative to those used in 802.11 η, and 802.11ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control/Machine-Type Communications (MTC), such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (for example, only support for) certain and/or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (for example, to maintain a very long battery life).

[0072] WLAN systems, which may support multiple channels, and channel bandwidths, such as

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

[0073] In the United States, the available frequency bands which may be used by 802.11 ah are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0074] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0075] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the

RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs

180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a,

102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 180b may utilize beamforming to transmit signals to and/or receive signals from the gNBs 180a, 180b, 180c. Also, in an example, gNBs 180a, 180b, 180c may utilize beamforming to transmit signals to and/or receive signals from the WTRUs 102a, 102b, 102c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers (not shown) to the WTRU 102a. A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180c).

[0076] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and/or

OFDM subcarrier spacing may vary for different transmissions, different cells, and/or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a,

180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths, for example, containing a varying number of OFDM symbols and/or lasting varying lengths of absolute time.

[0077] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a,

102b, 102c in a standalone configuration and/or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (for example, such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs

180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a,

102b, 102c may communicate with/connect to gNBs 180a, 180b, 180c while also communicating with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b,

102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a,

180b, 180c may provide additional coverage and/or throughput for servicing WTRUs 102a, 102b, 102c.

[0078] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E-

UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface. [0079] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF

184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0080] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (for example, handling of different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of non-access stratum (NAS) signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, and/or the like. The AMF 182a, 182b may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and/or non-Third Generation Partnership Project (3GPP) access technologies such as WiFi.

[0081] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0082] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet- switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, and the like.

[0083] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (for example, an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local DN 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0084] In view of FIGS. 1A-1 D, and the corresponding description of FIGS. 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions.

[0085] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and/or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and/or may perform testing using over-the-air wireless communications.

[0086] The one or more emulation devices may perform the one or more, including all, functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and/or a non- deployed (for example, testing) wired and/or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (for example, which may include one or more antennas) may be used by the emulation devices to transmit and/or receive data.

[0087] In LTE systems, OFDM may be used for DL transmission while DFT-s-OFDM may be used for UL transmission. In conventional Cyclic Prefix (CP) DFT-s-OFDM, sometimes referred to as SC- FDMA, the data symbols may be first spread with a discrete Fourier transform (DFT) block, and then may be mapped to the corresponding inputs of an inverse DFT (IDFT) block. The CP may be prepended to the beginning of the symbol in time in order to avoid inter-symbol interference (ISI) and may allow one-tap frequency domain equalization (FDE) at the receiver. Similarly, unique word (UW) DFT-s-OFDM may allow one-tap FDE by using a fixed sequence from the previous symbol's tail.

[0088] A transmitted waveform may be exposed to non-linear distortions due to non-ideal hardware characteristics in a communications link. Specifically, the impact of the non-ideal device characteristics may become more apparent at higher operating frequencies, for example, millimeter wave (mmW) or TeraHertz frequencies, and may cause more degradation of the link performance as compared to the those in traditional cellular frequencies. A possible impairment may be phase noise (PN), which may be magnified by the operating frequency of the communication link. Therefore, the 3GPP and IEEE links operating at higher frequencies may be more susceptible to impairment than the links operating at lower frequencies, for example, below 6 GHz. Such higher operating frequencies may be used in, for example, fifth generation (5G) NR and IEEE 802.1 1 ad/ay wireless communications systems.

[0089] At the transmitter and receiver side, the PN may be modelled in the baseband as

t = D_ptxu, Equation (1 ) and

y = D_Prxr, Equation (2) respectively, where u ε (C^Wxl is the baseband OFDM-based symbol, t ε (C^Wxl is the transmitted symbol after transmitter phase noise, r ε (C^Wxl is the OFDM symbol exposed to the multipath channel, y ε (C^Wxl is the received OFDM-based signal which may have the impacts of PN and multipath channel, D_Prx ε (C^WxW and D_Ptx ε (C^WxW are the diagonal matrices which may represent the impact of phase noise on the symbols where the norm of nth diagonal element is 1 , and N is the Fast Fourier Transform (FFT) size. For the sake of simplicity, additive white Gaussian noise (AWGN) is not represented in these equations.

[0090] Assuming that the circular convolution of the transmitted waveform with multipath channel response is approximately maintained via CP or UW, the received signal y may be expressed as

y = D_PrxHD_Ptx F¾_» Equation (3)

u

where x ε (C^Wxl is a vector which includes both the transmitted data symbols in frequency and the guard tones, where the data symbols are spread data symbols in the case of DFT-s-OFDM, H ε (C^WxW is a circular matrix, D_ptx and D_Prx are the diagonal matrices representing PN at transmitter and receiver, respectively, F ε (C^WxW is the DFT matrix, and (·)^Η is the Hermitian operation. By using the decomposition of a circular matrix C = F^HD_CF, (C is a circular matrix and D_c is the corresponding diagonal matrix), the output of the FFT block at the receiver, s , may be written as

s = Fy = FD_Prx H D_ptxF^Hx = FD_Pn F^HD_hFD_ptxF^Hx. Equation (4)

F^HD_hF

[0091] Equation (4) shows the impact of phase noise in the frequency domain. Moreover, since

C_p = FD_pF^H is a circular matrix, the vector s may be expressed as

s = C_Pn D_hC_ptxx. Equation (5) where Cp_rx represents phase noise in the receiver and Cptx represents phase noise in the transmitter. In other words, the impact of PN may be a circular convolution in the frequency domain at the transmitter and the receiver, which may affect all of the frequency bins.

[0092] FIG. 2 is a block diagram of an example of the impact of phase noise in the frequency domain with DFT-s-OFDM. As shown in an example in block diagram 200, the impact of the PN in the frequency domain may be exemplified by using a DFT-s-OFDM structure, and this impact may be shown in a circular convolution with the frequency response of PN over N bins. In an example, an M-point-DFT matrix block 220 may receive an input of data and/or fixed symbols, where M represents an M x M DFT matrix size. For example, if M = 3, the 3-point DFT matrix block would include a 3 x 3 DFT matrix. During transmission, reception, or both the output of the DFT matrix block 220 may be impacted by a circular convolution, which may be represented by *, over N bins. Further, the output of the DFT matrix block 220 may be input into an N-point-IDFT matrix block 240. The N-point-IDFT matrix block 240 may output one or more DFT-s-OFDM symbols for transmission by a wireless device, such as a base station or a WTRU.

[0093] Assuming that the WTRU's hardware introduces more PN as compared to the hardware of a base station or an eNode-B, the received signals in the uplink and downlink can approximately characterized as

^uplink ⁼ D_hC_Ptxx Equation (6) and

Sdowniink = ^c _Prx ^DhX, Equation (7) respectively.

[0094] Although the PN may be characterized as a circular convolution across the entire frequency bins, the impact of PN on data symbols cannot be directly modelled by using circular matrices at the receiver side. Therefore, the impact of PN on data symbols may not be diagonalized within the region of interest in the frequency domain and this may increase the complexity of the problem. This issue may be demonstrated with an example UL scenario as follows.

[0095] In an example, assuming that the data symbols d ε ⁽C^Mxl are spread via DFT-spread operation F_spread ε ⁽C^MxM, the vector x may be expressed as

x = M_txF_spreadd. Equation (8) where M_tx ε <C^NxM is the resource mapping matrix. Therefore, by using Equation (6), the impact of PN symbols in the frequency domain, on data and after IDFT de-spread operation may be expressed as

s = D_hC_Ptxx, Equation (9) and

d =

Equation (10) respectively, where M_rx ε <C^NxM is the resource de-mapping matrix. Assuming that the channel estimation and FDE may be done in an optimal manner, for example, using a zero forcing equalizer, the equalized signal may be shown as

d = F_s ^H _pread M_r ^H _xC_ptxM_tx F_spreadd, Equation (11)

p

where d is the output of IDFT-spread block at the receiver. Without loss of generality, for example, including the PN compensation, a generic estimator for d may be expressed as

d = Dp^equalizerFs^readPFspreadd Equation (12)

[0096] where d represents the data vector after the phase noise has been removed. If there is no phase noise, P = I (in other words, this is no phase error and there is a direct resource mapping) and ^DPN equalizer = l then d = d. On the other hand, if P≠ I, the impact of PN may be compensated by setting D_{PN equalizer} as, which may include, for example, zero forcing equalization for PN.

DpN_equalizer = (Fs^readPFspread) ■ Equation (13)

[0097] However, since M_rx is typically equivalent to M_tx and one may crop the rows and columns of the circular matrix C_Ptx in Equation (11), then P = M"_xC_PtxM_tx ε c^MxM may become a non- circulant matrix and may not be expressed in a form of FspreadApNF^_j-ea_j where Λ_ΡΝ ε c^MxM is a diagonal matrix related to PN. Therefore, D_PN equalizer ⁱⁿ Equation (13) may become a non-diagonal matrix that has non-diagonal terms, which may increase the complexity of the PN compensation at the receiver.

[0098] FIG. 3A is a block diagram of an example transmitter (Tx) for DFT-s-OFDM transmission.

As shown in an example in FIG. 3A, data symbols, which may be represented by d, may be spread by a DFT-operation, such as F_spread, in DFT block 310. The results of DFT block 310 may be mapped to subcarriers or resources by sub-carrier mapping block 320, which may apply resource mapping matrix, such as Mtx. The output, such as vector x, of sub-carrier mapping block 320 may undergo IFFT processing, such as F^H, by IFFT processing block 330. The results of IFFT processing block 330 may be a baseband OFDM-based symbol, such as symbol u, which may be then sent to a transmitter for transmission. The phase noise at the transmitter may be expressed by D_ptx at transmit phase noise model block 340 and may be included in a transmitted OFDM symbol after the transmitter phase noise, which may be represented by t. The transmitted symbol, such as t, may be transmitted over antenna 350.

[0099] FIG. 3B is a block diagram of an example receiver (Rx) for DFT-s-OFDM using PN correction. As shown in an example in FIG. 3B, antenna 355 may receive the OFDM symbol after exposure to the multipath channel, which may be represented by r. That symbol may be processed by the receive phase noise model block 360, where D_prx may express the phase noise at the receiver, resulting in an OFDM-based signal which includes the impacts of PN and the multipath channel, and which may be represented by y. A discrete Fourier transform matrix, which may be represented by F, may be applied to the OFDM-based signal at FFT block 365. The output of FFT block 365, which may be represented by s, may be demapped at sub-carrier demapping block 370 using a resource demapping matrix, such as M^H _rx. The output of sub-carrier demapping block 370 may undergo IDFT-spread processing, such as F^H _spread, by IDFT-spread processing block 380. The output of IDFT-spread processing block 380, which may be represented by d, may undergo PN correction or PN compensation, such as by applying UpN_equalizer, at PN equalizer 390. The output of PN equalizer 390, which may be represented by d, to generate a time domain signal which may be available for further baseband processing such as modulation demapper, decoding, and block error detection. In examples, the PN correction may be performed by a process, a method and/or an algorithm.

[0100] FIG. 4 is a signal diagram in frequency of an example of the impact of PN on data symbols. An example shown in signal diagram 400 illustrates the operation in Equation (9), assuming that the channel equalization is done where the elements of C_Ptx are in the data block are shown as {Po, p_lt ... , p_M--1}. In graph 450, the horizontal axis shows the signal in frequency without PN and the vertical axis shows the signal in frequency with PN. As shown in FIG. 4, the signal is transmitted without PN in frequency 460 but may be received with PN in frequency 410. Since the data block part 461 of vector x is padded with zeros to add guard tones, such as guard tones 462, 463, the data block part 461 of the vector x that the receiver may need to demodulate may observe linear convolution, and may not observe circular convolution. This may result in received signal vector s including a received data block part 411, PN parts 414, 415 and received guard tones 412, 413.

[0101] The impact of the PN on the data symbols and the performance of the PN mitigation methods and PN mitigation algorithms may depend on receiver complexity, signal design, and/or the amount of the PN. Therefore, the following challenges related to PN may appear in the communication link simultaneously. For example, there may be interference due to the PN. In this case, the impact of PN may be reduced or mitigated by considering direct current (DC) components of the PN only, known as common phase error (CPE). However, the interference among the symbols due to high frequency components of the PN may remain.

[0102] Another example of a PN challenge is receiver complexity. In this case, the available methods to reduce the inter-channel interference (I CI) due to PN may use an iterative receive structure which may involve multiple DFT/IDFT operations, which may be complex. The method expressed in Equation (12) may accurately mitigate the PN impact, but Equation (12) may require Equation (13) to be calculated and the matrix inverse operation in Equation (13) may be too complex to be efficiently calculated in the receiver at the handset or WTRU. [0103] Another example of a PN challenge is PN estimation. In this case, although there are mechanisms available to remove PN at the receiver side, the PN may need to be estimated first, which may be hard to do accurately in real time due to the wide bandwidth of the PN.

[0104] In order to address the above challenges, a simple method that enables a low-complexity receiver structure for PN mitigation, including both for CPE and ICI components, and PN estimation may be used. Such a low-complexity receiver structure for PN mitigation may be used in WTRUs.

[0105] Another example of a PN challenge is channel estimation. In this case, a transmitter structure that allows robust multipath channel estimation methods under PN may be used.

[0106] The complexity of the PN mitigation method or PN mitigation algorithm at the receiver may be addressed using frequency domain (FD) CP and CS. As discussed above, the impact of PN may be a circular convolution in the frequency domain. However, this circular convolution operation may involve N bins of a DFT matrix, which may include, for example, all of the subcarriers including the guard tones.

Therefore, a group of subcarriers that uses a subset of the N bins may approximately observe the circular convolution as a linear convolution. As a result, it may become a high complexity problem to equalize the signal distorted by the PN.

[0107] An example method to circumvent this signal distortion may be to add a CS and a CP of the IFFT input in the frequency domain to obtain a local circular convolution within M bins, where M < N, instead of N bins. The FD CS and CP may be used with both DFT-s-OFDM symbols and OFDM symbols.

[0108] FIG. 5A is a block diagram of an example FD CP and CS for DFT-s-OFDM. As shown in an example in FIG. 5A, DFT-s-OFDM processing by a wireless device, such as a base station or a WTRU, may be modified to include prepending and appending N_cp and N_cs samples to the output of the DFT- spread block. Specifically, an M-point-DFT matrix block 520 may receive an input of data and/or fixed symbols. The M-point-DFT matrix block 520 may output a data block 525 which may include a header 532 and a tail 534 along with a data sub-block 531. The header 532 may be replicated to create a CS 537 in frequency. Likewise, the tail 534 may be replicated to create a CP 539 in frequency. The data block 525, including the data sub-block 531 , the header 532 and the tail 534, may be input along with the CP 539 and CS 537 into an N-point-IDFT matrix block 540. Then, the N-point-IDFT matrix block 540 may output one or more DFT-s-OFDM symbols for transmission by the wireless device, including the data block, CP and CS. Approximate local circular convolution within M bins, instead of N bins, is obtained with the addition of the CP and the CS. As a result of the local circular convolution, the impact of ICI, which may be due to PN or any frequency dispersion, can be converted to a diagonal matrix multiplication after an M-IDFT operation at the receiver. Hence, the receiver may apply a single tap time domain equalization to compensate or mitigate the impact of ICI, which may be due to PN or any frequency dispersion. [0109] FIG. 5B is a block diagram of an example FD CP and CS for OFDM. As shown in an example in FIG. 5B, for an OFDM symbol, the block of data symbols may be prepended and appended by N_Cp and N_cs samples. In an example, the block of data symbols may be 12 subcarriers within 1 physical resource block (PRB) as used in LTE wireless systems. Specifically, an input of data and/or fixed symbols may undergo a direct subcarrier mapping 550 and, as in FIG. 5A, a header 562 of data block 555 may be replicated to create a CS 567 in frequency and a tail 564 of data block 555 may be replicated to create a CP 569. The data block 555, including a data sub-block 561 , the header 562 and the tail 564, may be input along with the CP 569 and CS 567 into an N-point-IDFT matrix 560. Then, the N-point-IDFT matrix block 560 may output one or more OFDM symbols for transmission by a wireless device including the data block, CP and CS. Approximate local circular convolution within M bins, instead of N bins, is obtained with the addition of CP and CS. As a result of the local circular convolution, the impact of I CI , which may be due to PN or any frequency dispersion, can be converted to a diagonal matrix multiplication after an M-IDFT operation at the receiver. Hence, the receiver may apply a single tap time domain equalization to compensate or mitigate the impact of I CI , which may be due to PN or any frequency dispersion.

[0110] FIG. 5C is a flow diagram of an example of generating an example FD CP and CS. In an example shown in FIG. 5C, a WTRU may generate an FD CS based on a replication of a header of a data block 502. The WTRU may also generate an FD CP based on a replication of a tail of the data block 503. The WTRU may then prepend the FD CP to the data block 504 and append the FD CS to the data block 505. Accordingly, the WTRU may map the FD CP, the data block and the FD CS to corresponding inputs of an IDFT block 507. Then, the WTRU may transmit the FD CP, the data block and the FD CS 509.

[0111] A same or similar procedure may also be performed by a base station. For example, a base station may generate an FD CS based on a replication of a header of a data block. The base station may also generate an FD CP based on a replication of a tail of the data block. The base station may then prepend the FD CP to the data block and append the FD CS to the data block. Accordingly, the base station may map the FD CP, the data block and the FD CS to corresponding inputs of an IDFT block. Then, the base station may transmit the FD CP, the data block and the FD CS.

[0112] FIG. 5D is a block diagram of an example of receiving FD CP and CS for DFT-s-OFDM. In an example shown in FIG. 5D, a wireless device, such as a base station or a WTRU, may receive one or more DFT-s-OFDM symbols including a data block, an FD CP and an FD CS, which may then be input into an N-point-DFT block 510. The data block may include a header, a data sub-block and a tail. The N-point- DFT block 510 may first calculate an N-point DFT of the received DFT-s-OFDM symbol(s) to obtain the frequency domain response of the signal, including an FD CP 512, a header 513, a data sub-block 515, a tail 516 and an FD CS 517. In the frequency domain, the wireless device may discard the FD CP 512 and the FD CS 517 and further calculate the M-IDFT of the received data block, including the header 513, the data sub-block 515 and the tail 516, using an M-point-IDFT block 518. Since FD CP and FD CS converts the impact of linear convolution of PN to a circular convolution, the output of the M-point-IDFT block 518 may be further processed by point-to-point multiplication via a single-tap time domain equalization block 519. The single-tap time domain equalization block 519 may receive noise variance and an estimate of time selectivity, and may include processing derived based on zero forcing or minimum mean square estimation (MMSE) criteria. The output of the single-tap time domain equalization block 519 may consist of data and/or fixed symbols which may be further processed by the subsequent receive operations such as demodulation and decoding.

[0113] FIG. 5E is a block diagram of an example of receiving FD CP and CS for OFDM. In an example shown in FIG. 5E, a wireless device, such as a base station or a WTRU, may receive one or more OFDM symbols including a data block, an FD CP and an FD CS, which may then be input into an N-point- DFT block 570. The data block may include a header, a data sub-block and a tail. The N-point-DFT block 570 may first calculate an N-point DFT of the received OFDM symbol(s) to obtain the frequency domain response of the signal, including an FD CP 572, a header 573, a data sub-block 575, a tail 576 and an FD CS 577. In the frequency domain, the wireless device may discard the FD CP 572 and the FD CS 577 and further calculate the M-IDFT of the received data block, including the header 573, the data sub-block 575 and the tail 576, using an M-point-IDFT block 580. As in FIG. 5D, in FIG. 5E, the output of M-point-IDFT block 580 may be further processed by point-to-point multiplication via a single-tap time domain equalization block 585. The single-tap time domain equalization block 585 may receive noise variance and an estimate of time selectivity, and may include processing derived based on zero forcing or MMSE criteria. An M-point-DFT block 590 may calculate an M-DFT of the output of the single-tap time domain equalization block 585. The output of the M-point-DFT block 590 may consist of data and/or fixed symbols which may be further processed by subsequent receive operations such as demodulation and decoding.

[0114] FIGS. 6A and 6B are signal diagrams in frequency of examples of the impact of PN on data symbols with CP and CS. As shown in the examples in FIGS. 6A and 6B, since CP and CS may contain symbols from the same transmitted block in frequency, they may convert the linear convolution 625 in graph 620 of FIG. 6A to a local circular convolution 655 in graph 650 of FIG. 6B within the part of the signal that the receiver needs to demodulate, which is shown in the black region in the received signal vector of FIG. 6B. As shown in FIG. 6A, the signal is transmitted without PN in frequency 630 but may be received with PN in frequency 610. Accordingly, data block part 631 of the vector x is transmitted with CP 639 and CS 637 along with guard tones 632, 633. This may result in received signal vector s including a received data block part 611 , a received CP 619, a received CS 617, PN parts 614, 615 and received guard tones 612, 613.

[0115] In comparison to FIG. 6A, FIG. 6B shows re-expression of PN with a local circular convolution 655. As shown in FIG. 6B, the signal is transmitted without PN in frequency 660 but may be received with PN in frequency 670. Since data block part 661 of the vector x is transmitted with CP 669 and CS 667 along with guard tones 662, 663, the data block part 661 of the vector x that the receiver may need to demodulate may observe local circular convolution at the receiver, resulting in the received data block 671. This may result in received signal vector s including a received data block part 671 , a received CP 679, a received CS 677, PN parts 674, 675 and received guard tones 672, 673. As a result, the matrix ¾read^PFs_Pread of Equation (12) may become diagonal, such that the PN equalization may become a one-tap equalizer. Such a one-tap equalizer provides a low-complexity solution for use by the receiver of a wireless device, such as the receiver of a WTRU.

[0116] The following design considerations may need to be taken into account in example concepts herein. In an example design consideration, the transmitted symbols may be reference symbols (RSs), data symbols, or both for DFT-s-OFDM and/or OFDM. For example, the transmitted symbols may have hybrid utilization as both RSs and data symbols.

[0117] In another example design consideration, the sizes of N_cs and N_cp may depend on the power spectral density (PSD) of the PN, and the sizes of N_cs and N_cp may be chosen by considering a worst-case scenario and/or depending on the device's PN characteristics in flexible manner. For example, if the maximum frequency dispersion is targeted at 500 kHz due to PN and the subcarrier spacing is 240 kHz, then the use of a ceiling operation may demonstrate that at least [500/2401 = 3 samples may be considered for N_cs and N_cp. Using N_cs and N_cp samples may increase the overhead of the transmitted signal. Hence, the sizes of N_cs and N_cp may be minimized. In addition, the receiver may signal N_cs and Ncp to the transmitter. N_cs and N_cp may be adaptively chosen depending on the size of the resource allocation. For example, if the size of the resource allocation is large, N_cs and N_cp may be increased to increase the protection from ΡΝ.

[0118] In another example design consideration, the CP and CS parts in the frequency domain may also include an additional frequency windowing operation. Further, the CP and CS parts in the frequency domain may be extended for a given windowing function in frequency.

[0119] In another example design consideration, when multiple WTRUs are transmitting in the UL direction, the WTRUs that are allocated to adjacent frequency (sub)bands may map their data to the subcarriers such that the prefix and suffix generated by these WTRUs may overlap. Various examples are shown in FIGS. 7, 8 and 9.

[0120] FIG. 7 is a block diagram of an example FD CS and CP for DFT-s-OFDM with two

WTRUs. An example in block diagram 700 shows DFT-s-OFDM processing where the prefix of WTRU 2 and suffix of WTRU 1 are mapped to the same subcarriers. The sizes of the suffix and prefix may be different, and the overlap may be partial. [0121] In an example, in a first WTRU, an M-point-DFT matrix block 720 may receive an input of data and/or fixed symbols. The M-point-DFT matrix block 720 may output a data block 725 which may include a data sub-block 731 , a header 732 and a tail 734. The header 732 may be replicated to create a CS 737 in frequency. Likewise, the tail 734 may be replicated to create a CP 739 in frequency. The data block 725, including the data sub-block 731, the header 732 and the tail 734, may be input along with the CP 739 and CS 737 into an N-point-IDFT matrix block 740. Then, the N-point-IDFT matrix block 740 may output one or more DFT-s-OFDM symbols for transmission by the first WTRU.

[0122] Further, in a second WTRU, an M-point-DFT matrix block 750 may receive an input of data and/or fixed symbols. The second WTRU may transmit on a band adjacent to the transmissions of the first WTRU. The M-point-DFT matrix block 750 may output a data block 755 which may include a data sub- block 761 , a header 762 and a tail 764. The header 762 may be replicated to create a CS 767 in frequency. Likewise, the tail 764 may be replicated to create a CP 769 in frequency. The data block 755, including the data sub-block 761 , the header 762 and the tail 764, may be input along with the CP 769 and CS 767 into an N-point-IDFT matrix 770. Then, the N-point-IDFT matrix block 770 may output one or more DFT-s- OFDM symbols for transmission by the second WTRU. During transmission of the DFT-s-OFDM symbols, the CS 737 of the first WTRU may overlap with the CP 769 of the second WTRU.

[0123] FIG. 8 is a block diagram of an example FD CS and CP for OFDM with two WTRUs. An example in block diagram 800 shows OFDM processing where the prefix of WTRU 2 and suffix of WTRU 1 are mapped to the same subcarriers. As in examples in FIG. 7, the sizes of the suffix and prefix may be different, and the overlap may be partial in examples in FIG. 8.

[0124] In an example, in a first WTRU, an input of data and/or fixed symbols may undergo a direct subcarrier mapping 820 and a header 832 and a tail 834 of data block 825 may be replicated to create a CS 837 and a CP 839, respectively. The data block 825, including a data sub-block 831 , the header 832 and the tail 834, may be input along with the CP 839 and CS 837 into an N-point-IDFT matrix block 840. Then, the N-point-IDFT matrix block 840 may output one or more OFDM symbols for transmission by the first WTRU.

[0125] Further, in a second WTRU, an input of data and/or fixed symbols may undergo a direct subcarrier mapping 850 and a header 862 and a tail 864 of data block 855 may be replicated to create a CS 867 and a CP 869, respectively. The data block 855, including a data sub-block 861 , the header 862 and the tail 864, may be input along with the CP 869 and CS 867 into an N-point-IDFT matrix 870. Then, the N-point-IDFT matrix block 870 may output one or more OFDM symbols for transmission by the second WTRU. During transmission of the OFDM symbols, the CS 837 of the first WTRU may overlap with the CP 869 of the second WTRU.

[0126] The same concept or a similar concept may be applicable to other types of wireless transmission processing, such as hybrid DFT-s-OFDM transmission processing. Further, the same concept or a similar concept may also be applicable to the case where data is transmitted from a single node, as illustrated in FIGS. 9A and 9B.

[0127] FIGS. 9A and 9B are block diagrams of an example FD CS and CP for multiple data allocations. As shown in an example in the block diagrams in FIGS. 9A and 9B, a single node, such as a single WTRU or a single base station, may transmit multiple data allocations. When there are adjacent allocations for different data, the prefix and suffix corresponding to the adjacent allocations may wholly or partially overlap.

[0128] In an example shown in FIG. 9A, in a single WTRU, a first M-point-DFT matrix block 920 may receive an input of data and/or fixed symbols. The first M-point-DFT matrix block 920 may output a data block 923 which may include a data sub-block 931 , a header 932 and a tail 934. The header 932 may be replicated to create a CS 937 in frequency. Likewise, the tail 934 may be replicated to create a CP 939 in frequency. The data block 923, including the data sub-block 931 , the header 932 and the tail 934, may be input along with the CP 939 and CS 937 into an N-point-IDFT matrix block 940.

[0129] Further, in the single WTRU, a second M-point-DFT matrix block 922 may receive an input of data and/or fixed symbols. The first M-point-DFT matrix block 922 may output a data block 925 which may include a data sub-block 941 , a header 942 and a tail 944. The header 942 may be replicated to create a CS 947 in frequency. Likewise, the tail 944 may be replicated to create a CP 949 in frequency. The data block 925, including the data sub-block 941 , the header 942 and the tail 944, may be input along with the CP 949 and CS 947 into the N-point-IDFT matrix block 940. Then, the N-point-IDFT matrix block 940 may output one or more DFT-s-OFDM symbols for transmission by the single WTRU. During transmission of the DFT-s-OFDM symbols in adjacent bands, the CS 937 of the first M-point-DFT matrix block 920 may overlap with the CP 949 of the second M-point-DFT matrix block 922.

[0130] In an additional example shown in FIG. 9B, in a single WTRU, an input of data and/or fixed symbols may undergo a direct subcarrier mapping 950 and a header 962 and a tail 964 of a data block 953 may be replicated to create a CS 967 and a CP 969, respectively. The data block 953, including a data sub-block 961 , the header 962 and the tail 964, may be input along with the CP 969 and CS 967 into an N- point-IDFT matrix block 970.

[0131] Further, in the single WTRU, an input of data and/or fixed symbols may undergo a direct subcarrier mapping 952 and a header 972 and a tail 974 of a data block 955 may be replicated to create a CS 977 and a CP 979, respectively. The data block 955, including a data sub-block 971 , the header 972 and the tail 974, may be input along with the CP 979 and CS 977 into the N-point-IDFT matrix block 970. During transmission of the OFDM symbols in adjacent bands, the CS 967 may overlap with the CP 979. Further, during transmission of the symbols, the CS 937, CP 949, CS 967 and CP 979 may be mapped to same subcarrier(s) and may be summed before subcarrier mapping. [0132] In an example, the output of N-point-IDFT matrix block 940 of FIG. 9A and the output of N- point-IDFT matrix block 970 of FIG. 9B may be transmitted using a single antenna. Further, the DFT- spread operations may be performed in parallel and may use a large bandwidth. Accordingly, a WTRU may transmit both OFDM and DFT-S-OFDM symbols. In another example, a WTRU may transmit only the OFDM symbols. In an additional example, a WTRU may transmit only DFT-S-OFDM symbols. Further, a WTRU may transmit a hybrid DFT-s-OFDM and OFDM transmission.

[0133] In another example design approach, methods may be used for extension indication and/or configuration. Because FD CP and CS extends a data block by prepending CP and appending CS in frequency, it may be useful or necessary to avoid or reduce the interference due to the existence of CP and/or CS in multiple accessing scenarios in the uplink. In an example accessing scenario, if WTRU1 is assigned to use resource block(s) (RB(s)) that are utilized by WTRU2 for the spectrum extension, WTRU1 data may experience interference due to WTRU2's spectrum extension.

[0134] An example approach to avoid such interference is to reduce the size of the DFT matrix so that the CP and CS are inserted within the RB(s) that are utilized by the user itself for user data. In this case, the size of CP/CS subcarriers may be configured or known by the eNode-B.

[0135] In another example method to avoid interference between WTRUs due to overlapping that may be caused by using CP and/or CS, WTRU Capability information may be used such that the support of WTRU spectrum extension and/or type of WTRU spectrum extension may be indicated in the capability fields of the WTRU transmitters. For example, the indication may use M bits in the capability fields. Further, the extension size on the edges may be fixed and/or may be indicated by WTRU. In examples, the extension size may be fixed at 1 RB or K subcarriers.

[0136] Also, different spectrum shaping operations may be defined. Example shaping operations may include windowing on the data block alone, windowing on the data block, CP, and CS together, and the like. The shaping functions may be indicated by defining a bitmap, a table or individual bits, or may not be specified if deemed transparent to the receiver. The parameters of a predetermined shaping function may be indicated. The indication may include, for example, a roll-off factor of a resistor-capacitor (RC) filter. Further, The WTRU may indicate if the filter satisfies the vestigial symmetry property or not. The shaping function, which may include CP and CS, may be a function of a modulation and coding type/rate, and/or a number of subcarriers used in the transmission.

[0137] In another example method to avoid interference between WTRUs due to overlapping, that may be caused by using a CP and/or a CS, configuration-based avoidance may be used. In an example, the eNode-B may configure the WTRU if the WTRU transmitter can use spectrum extension and/or shaping along with the corresponding parameters. For example, the eNode-B may configure the extension size of the edges, for example, K subcarriers, or they may be indicated by the WTRU as part of WTRU Capability information. Different spectrum shaping operations may be defined. Example spectrum shaping operations may include windowing, windowing + CP + CS, only CP and CS, and the like. The shaping functions may be indicated by defining a bitmap, a table or individual bits, or may not be specified if deemed transparent to the receiver. The shaping function may be a function of a modulation and coding type/coding rate, or a number of subcarriers used in the transmission. Also, the parameters of a predetermined shaping function may be indicated. The indication may include, for example, a roll-off factor of an RC filter. The eNode-B may indicate if the WTRU can use a filter that satisfies the vestigial symmetry property.

[0138] In example methods for PN estimation and PN equalization, PN RSs) may be used to address the PN estimation problem. An example method to estimate the PN may be to use RSs in the time domain.

[0139] FIG. 10 is a block diagram of an example RS transmission with FD CP and CS. In an example shown in block diagram 1000, in order to achieve time-domain RS, some of the input of an M- point-DFT-spread block 1020 may be used to place RSs along with the FD CP and CS. For example, before the RSs are added to the M-point-DFT-spread block 1020, the power level of the RSs may be adjusted 1010. The RSs, data symbols and/or fixed symbols may then be input into the M-point-DFT- spread block 1020. The M-point-DFT matrix block 1020 may output a data block 1025 which may include a data sub-block 1031 , a header 1032 and a tail 1034. The header 1032 may be replicated to create a CS 1037 in frequency. Likewise, the tail 1034 may be replicated to create a CP 1039 in frequency. The data block 1025, including the data sub-block 1031 , the header 1032 and the tail 1034, may be input along with the CP 1039 and CS 1037 into an N-point-IDFT matrix block 1040. Then, the N-point-IDFT matrix block 1040 may output one or more DFT-s-OFDM symbols for transmission by a wireless device.

[0140] The absence of FD CP and CS may cause interference among the data and RSs, and/or may reduce the PN estimation performance. On the other hand, using time-domain RSs with FD CP 1039 and FD CS 1037 may allow the receiver to characterize the impact of PN as a diagonal matrix after an IDFT de-spread operation. Hence, it may be possible to estimate the PN with FD CP 1039 and FD CS 1037 by only observing the RS or RSs placed at the input of DFT-spread, such as the input of the M-point- DFT-spread block 1020.

[0141] The following considerations may be taken into account in the design of the structure given in FIG. 10. In an example consideration, the density of the RSs may be a function of the PN PSD. Therefore, the density of the RSs may be signaled in some scenarios to avoid overprotection. In another example consideration, the RSs may be uniformly or non-uniformly distributed in the time domain. In a further example consideration, the transmitter may adjust the power level of the RSs by a factor of a and the value of a may be signaled to the transmitter for proper PN estimation. In an additional example consideration, the RS may be a sequence that allows low peak-to-average power ratio (PAPR). Example sequences may include a Golay sequence, a Zadoff-Chu (ZC) sequence and the like. In this case, the RS may be rotated with Θ degrees in every sample, for example, π/2 or π/4.

[0142] In an example, differential modulation may be used for DFT-S-OFDM processing. For example, PN can vary within a symbol, such as a DFT-s-OFDM symbol duration. However, a correlation between the amount of distortion of adjacent modulation symbols may be high when FD CP and FD CS are used in the waveform structure. Therefore, one may use differential modulation to exploit the correlation between the distortion of adjacent modulation symbols.

[0143] FIG. 11 is a block diagram of an example exploitation of diagonalized PN structure with differential modulations. In an example shown in block diagram 1100, differential modulation may be used to exploit the correlation between the distortion of adjacent symbols. As a result, any received difference in the adjacent symbols may be attributable to differential modulation information and may be understood to not be attributable to a difference in distortion between the adjacent symbols.

[0144] The following considerations may be taken into account when differential modulation is used in this waveform structure. As an example consideration, at least one of the data symbols may be fixed for differential modulation. Hence, the maximum number of data symbols that may be transmitted in this scheme is M - 1 when the DFT-spread size is M. In an example, M - 1 differentially modulated symbols, which may include data and/or fixed symbols, may be input into an M-point-DFT matrix block 1120. The M-point-DFT matrix block 1120 may output a data block 1125 which may include a header 1132 and a tail 1134 along with a data sub-block 1131. The header 1132 may be replicated to create a CS 1137 in frequency. Likewise, the tail 1134 may be replicated to create a CP 1139 in frequency. The data block 1125, including the data sub-block 1131, the header 1132 and the tail 1134, may be input along with the CP 1139 and CS 1137 into an N-point-IDFT matrix block 1140. Then, the N-point-IDFT matrix block 1140 may output one or more DFT-s-OFDM symbols for transmission by the wireless device.

[0145] The robustness of differential modulation against noise may be increased by increasing the number of fixed symbols, for example. In another example consideration, the inputs of the DFT-spread blocks may be grouped and the differential modulation may be applied within the group. In this case, the size of the group may be standardized. In another example consideration, differential modulation may be multi-dimensional, which may increase the Euclidian distance between the symbols. For differential modulations, at least one of the data symbols may be fixed. Hence, the overhead may be at least one symbol. The fixed data symbol may be used as a differential modulation reference symbol.

[0146] In another example, differential modulations may be used for UW DFT-S-OFDM. In the case that the DFT-spread size is M and because in differential modulations at least one of the data symbols may be fixed, the maximum number of data symbols transmitted may be M-1. Further, this approach may use blind PN compensation. [0147] FIG. 12 is a block diagram of an example exploitation of unique word (UW) DFT-s-OFDM for differential modulations. As shown in an example in block diagram 1200, one method to avoid loss is to utilize UW and choose the right-most symbols 1275 of UW U₁ symbols 1270 and the left-most symbols 1285 of UW U₂ symbols 1280, which may be used as RSs for differential modulation. Therefore, the fixed UW sequence may be utilized to compensate the loss in differential modulation. In an example, M - 1 - Ui - U2 differentially modulated symbols, which may include data and/or fixed symbols, along with UWs Ui 1270 and U2 1280 may be input into an M-point-DFT matrix block 1220. The M-point-DFT matrix block 1220 may output a data block 1225 which may include a header 1232 and a tail 1234 along with a data sub-block 1231. The header 1232 may be replicated to create a CS 1237 in frequency. Likewise, the tail 1234 may be replicated to create a CP 1239 in frequency. The data block 1225, including the data sub-block 1231 , the header 1232 and the tail 1234, may be input along with the CP 1239 and CS 1237 into an N-point-IDFT matrix block 1240. Then, the N-point-IDFT matrix block 1240 may output one or more DFT-s-OFDM symbols for transmission by the wireless device. In this way, the UWs may be used to regenerate one or more fixed RSs for differential modulation. Specifically, symbols 1275 and symbols 1285 may be used as differential modulation RSs. Further, this approach may use blind PN compensation.

[0148] The following parameters may be designed for differential modulation for UW DFT-S-

OFDM. For example, differential modulation may not be efficient under power-limited conditions.

[0149] FIG. 13 is a block diagram of an example hybrid utilization of differential modulation and quadrature amplitude modulation (QAM). The density of the differential modulation may be reduced and/or its power may be increased, as shown in an example in block diagram 1300. For example, after the PN is estimated by exploiting the differentially modulated symbols and using UW, the impact of the PN may be removed on other data symbols, for example, QAM symbols, after an interpolation operation. Hence, the density of the QAM symbols and the density of the differential modulation symbols as well as their power levels may be fed-forward to the receiver. This improves the efficiency of using differential modulation under power-limited conditions by eliminating the need for differential modulation RSs apart from the UWs and thereby reducing transmission overhead. In addition, the power saved by not transmitted differential modulation RSs may be used for other purposes, such as transmitting payload data, extending battery life and the like.

[0150] In an example, before the symbols with differential modulation are added to an M-point-

DFT-spread block 1320, the power level of the symbols with differential modulation may be adjusted 1310. The symbols with differential modulation, data symbols, which may be QAM symbols and/or fixed symbols along with UWs Ui 1370 and U₂ 1380 may then be input into the M-point-DFT-spread block 1320. The M- point-DFT matrix block 1320 may output a data block 1325 which may include a data sub-block 1331, a header 1332 and a tail 1334. The header 1332 may be replicated to create a CS 1337 in frequency. Likewise, the tail 1334 may be replicated to create a CP 1339 in frequency. The data block 1325, including the data sub-block 1331 , the header 1332 and the tail 1334, may be input along with the CP 1339 and CS 1337 into an N-point-IDFT matrix block 1340. Then, the N-point-IDFT matrix block 1340 may output one or more DFT-s-OFDM symbols for transmission by a wireless device. In this way, the UWs may be used as one or more fixed RSs for differential modulation. Specifically, UW 1370 and UW 1380 may be used as differential modulation RSs.

[0151] In an example, thinning in the frequency domain may be used to address robust channel estimation under PN. In a further example, thinning in the frequency domain may be used for data symbols. Because the impact of PN is a convolution operation in frequency, one method to decrease interference between the symbols located on the adjacent bins may be to add or generate null symbols. Accordingly, increasing the spacing between symbols may decrease the impact of PN convolution in frequency between symbols.

[0152] FIGS. 14A, 14B and 14C are block diagrams of example methods for frequency thinning.

As shown in examples in FIGS. 14A, 14B and 14C, any of the following methods may be used for generating null symbols or zero symbols in frequency, in any combination: replicating the input of the DFT- spread block, which may or may not entail a change in the hardware used; interleaving the output of the DFT-spread block; making the size of DFT-spread adjustable; and/or using an interleaved mapping, which may be suitable for OFDM. As used herein, generating null symbols or zero symbols in frequency may be referred to as thinning in the frequency domain. By interleaving in frequency, the interference between the neighboring symbols may be mitigated. As used herein, interleaving may also be referred to as scrambling.

[0153] FIG. 14A shows an example of replicating the input of the DFT-spread block. In an example, data and/or fixed symbols may be replicated at a replication block 1410. As a result, an M-point- DFT matrix block 1420 may receive an input of the replicated data and/or fixed symbols. The output of the M-point-DFT matrix block 1420 may be mapped to the frequency domain. The replication output of replication block 1410 may be used as the input of the M-point-DFT matrix block 1420 and may cause the output of the M-point-DFT matrix block 1420 to be interleaved in frequency. For example, if the replication block 1410 replicates the data stream by a replication factor of two, one or more zero symbols will be mapped to every other subcarrier. In an example, the output of the M-point-DFT matrix block 1420 may include a precoded symbol 1421 , followed by a zero symbol 1422, which is in turn followed by another precoded symbol 1423, and so forth through precoded symbol 1428 and zero symbol 1429. The output of M-point-DFT matrix block 1420 may be input into an N-point-IDFT matrix block 1440. Then, the N-point- IDFT matrix block 1440 may output one or more DFT-s-OFDM symbols for transmission by the wireless device. Since the impact of PN is convolution in the frequency domain, the neighboring symbols may significantly affect each other. [0154] FIG. 14B shows an example of interleaving the output of the DFT-spread block. In an example, an M-point-DFT matrix block 1450 may receive an input of data and/or fixed symbols. The output of the M-point-DFT matrix block 1450 may be interleaved at interleave block 1460 by expanding the output of DFT matrix and placing zeros between the elements of the output of the DFT matrix block. For example, the output of the interleave block 1460 may include a precoded symbol 1461 , followed by a zero symbol 1462, which is in turn followed by another precoded symbol 1463, and so forth. As a result, the interference between the neighboring elements is mitigated in case of time selectivity or frequency dispersion. In a further example, the interleave block 1460 may change the order of the data sent in precoded symbols 1461 and 1463 as compared with the order of the data input into the interleave block 1460. In an example, the size of DFT-spread may be adjustable. The interleaved data and/or fixed symbols may be input into an N-point-IDFT matrix block 1470. Then, the N-point-IDFT matrix block 1470 may output one or more DFT-s- OFDM symbols for transmission by the wireless device. As a result of interleaving in frequency, the interference between the neighboring symbols may be mitigated.

[0155] FIG. 14C shows an example of interleaved mapping. In an example, an input of the replicated data and/or fixed symbols may be interleaved at interleave block 1480. For example, the output of the interleave block 1480 may include a precoded symbol 1481 , followed by a zero symbol 1482, which is in turn followed by another precoded symbol 1483, and so forth. This approach may be suitable for generating OFDM symbols. The interleaved data and/or fixed symbols may be input into an N-point-IDFT matrix block 1490. Then, the N-point-IDFT matrix block 1490 may output one or more OFDM symbols for transmission by the wireless device. As a result, the interference between the data symbols in frequency is mitigated in case of time selectivity or frequency dispersion.

[0156] FIG. 15 is a block diagram of example methods for frequency thinning for UW DFT-s-

OFDM. In an example shown in block diagram 1500, data, QAM, differential modulation and/or fixed symbols may be replicated at a replication block 1510. As a result, an M-point-DFT matrix block 1520 may receive an input of the replicated data, QAM, differential modulation and/or fixed symbols. The replication output of replication block 1510 may be used as the input of the M-point-DFT matrix block 1520 and may cause the output of the M-point-DFT matrix block 1520 to be interleaved in frequency. For example, if the replication block 1510 replicates the data stream by a replication factor of four, one or more zero symbols will be mapped to every four subcarriers. In an example, the output of the M-point-DFT matrix block 1520 may include a precoded symbol 1521 , followed by three zero symbols 1522, 1523, 1524, which are in turn followed by another precoded symbol 1525, which is in turn followed by three zero symbols 1526, 1527, 1528, and so forth through precoded symbol 1531 and zero symbols 1532, 1533, 1534. The output of M- point-DFT matrix block 1520 may be input into an N-point-IDFT matrix block 1540. Then, the N-point-IDFT matrix block 1540 may output one or more DFT-s-OFDM symbols for transmission by the wireless device. [0157] In an example case, the parameters that may be fed forward to receiver may include, but are not limited to include, any of the following parameters: the interleaving pattern; and/or the replication factor.

[0158] In an example, some output samples from the output of the IDFT may be punctured for insertion of RSs. Since the output of the IDFT may take the form of a repetition of signal blocks due to the interleaved mapping, puncturing samples may have a reduced impact. The punctured samples may be chosen to be different in each of the repetitive signal blocks.

[0159] FIG. 16 is a block diagram of example methods for frequency thinning and RS insertion after inverse discrete Fourier transform (IDFT). An example in block diagram 1600, an input of the replicated data and/or fixed symbols may be interleaved at interleave block 1630. For example, the output of the interleave block 1630 may include a precoded symbol 1631 , followed by a zero symbol 1632, which is in turn followed by another precoded symbol 1633, and so forth. This approach may be suitable for generating OFDM symbols. The interleaved data and/or fixed symbols may be input into an N-point-IDFT matrix block 1640. Then, the N-point-IDFT matrix block 1640 may output one or more OFDM symbols with repetitive structure. In an example, repeating data symbols may be seen at the output of the N-point-IDFT block 1640. In a further example shown in FIG. 16, repeating sub-symbols 1652, 1654, 1656 may be punctured for insertion of RSs at different locations in each sub-symbol. The one or more OFDM symbols with RSs may then be provided for transmission by the wireless device.

[0160] In addition, while FIG. 16 shows a sample example for OFDM, in other examples, the concept may be applied to DFT-s-OFDM and its variants as well. In a further example, the puncturing may be performed in the time domain.

[0161] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element may be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, WTRU, terminal, base station, RNC, or any host computer.

Claims

CLAIMS What is claimed:

1. A method for use in a wireless transmit/receive unit (WTRU) to reduce phase noise (PN), the method comprising:

generating, by the WTRU, a frequency domain (FD) cyclic suffix (CS) based on a replication of a header of a data block;

generating, by the WTRU, an FD cyclic prefix (CP) based on a replication of a tail of the data block; prepending, by the WTRU, the FD CP to the data block;

appending, by the WTRU, the FD CS to the data block;

mapping, by the WTRU, the FD CP, the data block and the FD CS to corresponding inputs of an inverse discrete Fourier transform (IDFT) block; and

transmitting, by the WTRU, the mapped FD CP, data block and FD CS.

2. The method of claim 1 , further comprising:

spreading, by the WTRU, data symbols of the data block using a discrete Fourier transform (DFT) operation.

3. The method of claim 1 , wherein the FD CP, the data block and the FD CS are transmitted as one or more discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s- OFDM) symbols.

4. The method of claim 1 , wherein the FD CP, the data block and the FD CS are transmitted as one or more orthogonal frequency division multiplexing (OFDM) symbols.

5. The method of claim 1 , wherein the FD CP, the data block and the FD CS are transmitted as part of a hybrid DFT-s-OFDM and OFDM transmission.

6. The method of claim 1 , further comprising:

transmitting, by the WTRU, one or more reference symbols (RSs), wherein the power level of the RSs is adjusted.

7. The method of claim 1 , further comprising:

transmitting, by the WTRU, one or more demodulation RSs, wherein each demodulation RS is part of a unique word (UW).

8. A method for use in a wireless transmit/receive unit (WTRU) to reduce phase noise (PN), the method comprising:

receiving, by the WTRU, a frequency domain (FD) cyclic suffix (CS), a data block and an FD cyclic prefix (CP);

discarding, by the WTRU, the FD CS and FD CP from the data block; processing, by the WTRU, the data block using single-tap time domain equalization including point- to-point multiplication; and

demodulating, by the WTRU, the processed data block.

9. The method of claim 8, wherein the FD CP, the data block and the FD CS are received as one or more discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) symbols.

10. The method of claim 8, wherein the FD CP, the data block and the FD CS are received as one or more orthogonal frequency division multiplexing (OFDM) symbols.

11. The method of claim 8, wherein the FD CP, the data block and the FD CS are received as part of a hybrid DFT-s-OFDM and OFDM transmission.

12. The method of claim 8, further comprising:

receiving, by the WTRU, one or more demodulation RSs, wherein each demodulation RS is part of a unique word (UW).

13. A wireless transmit/receive unit (WTRU) to reduce phase noise (PN), the WTRU comprising:

a processor configured to generate a frequency domain (FD) cyclic suffix (CS) based on a replication of a header of a data block;

the processor configured to generate an FD cyclic prefix (CP) based on a replication of a tail of the data block;

the processor configured to prepend the FD CP to the data block;

the processor configured to append the FD CS to the data block;

the processor configured to map the FD CP, the data block and the FD CS to corresponding inputs of an ID FT block;

a transceiver operatively coupled to the processor, the transceiver configured to transmit the mapped FD CP, data block and FD CS.

14. The WTRU of claim 13, wherein the processor is further configured to spread data symbols of the data block using a discrete Fourier transform (DFT) operation.

15. The WTRU of claim 13, wherein the FD CP, the data block and the FD CS are transmitted as one or more discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s- OFDM) symbols.

16. The WTRU of claim 13, wherein the data block and the FD CS are transmitted as one or more orthogonal frequency division multiplexing (OFDM) symbols.

17. The WTRU of claim 13, wherein the FD CP, the data block and the FD CS are transmitted as part of a hybrid DFT-s-OFDM and OFDM transmission.

18. The WTRU of claim 13, wherein the transceiver is further configured to transmit one or more reference symbols (RSs), wherein the power level of the RSs is adjusted.

19. The WTRU of claim 13, wherein the transceiver is further configured to transmit one or more demodulation RSs, wherein each demodulation RS is part of a unique word (UW).

20. A wireless transmit/receive unit (WTRU) to reduce phase noise (PN), the WTRU comprising:

a transceiver configured to receive a frequency domain (FD) cyclic suffix (CS), a data block and an FD cyclic prefix (CP);

a processor operatively coupled to the processor, the processor configured to discard the FD CS and FD CP from the data block;

the processor configured to process the data block using single-tap time domain equalization including point-to-point multiplication; and

the processor configured to demodulate the processed data block.

21. The WTRU of claim 20, wherein the FD CP, the data block and the FD CS are received as one or more discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) symbols.

22. The WTRU of claim 20, wherein the FD CP, the data block and the FD CS are received as one or more orthogonal frequency division multiplexing (OFDM) symbols.

23. The WTRU of claim 20, wherein the FD CP, the data block and the FD CS are received as part of a hybrid DFT-s-OFDM and OFDM transmission.

24. The WTRU of claim 20, wherein the transceiver is further configured to receive one or more demodulation RSs, wherein each demodulation RS is part of a unique word (UW).