Methods for flexible reference signal transmission with single carrier frequency domain multiple access (sc-fdma) and ofdma

Abstract

To disclose a method for transmitting a discrete fourier transform (DFT) DFT-S-OFDM signal including frequency domain reference symbols.SOLUTION: A method comprises the steps of: determining to null a plurality of data symbols prior to DFT-spreading; performing DFT-spreading including the determined null data symbols; puncturing an interleaved output of the DFT-spreading; inserting reference symbols in a frequency domain of the punctured and interleaved DFT-S-OFDM signal; and transmitting the DFT-S-OFDM signal with inserted reference symbols to a receiver. The transmitted DFT-S-OFDM signal enables the receiver to apply zeros corresponding to the reference symbols to an interleaved input of DFT-despreading, and cancel interference due to the puncturing by using all outputs of the DFT-despreading.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for flexible reference signal transmission using Single Carrier Frequency Division Multiple Access (SC-FDMA) and OFDMA. [Background technology]

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 373,126, filed August 10, 2016, and U.S. Provisional Patent Application No. 62 / 479,792, filed March 31, 2017, the contents of which are incorporated herein by reference.

[0003] In typical single-carrier frequency division multiple access (SC-FDMA) communications, such as those used in Long Term Evolution (LTE) uplink transmissions, a reference signal (RS) for data transmission can only be assigned to two time-domain symbol positions, and no data symbols can be transmitted at these positions. Summary of the Invention [Problem to be solved by the invention]

[0004] This overhead, in terms of resource usage, is fixed for all users, no matter how different the channel conditions are between users, and cannot be dynamically changed based on the channel conditions and service needs. For example, in a low SINR and ultra-reliable application scenario, adding additional RSs allows the receiver to perform more accurate channel estimation, and thus data can be detected with a low error rate. On the other hand, in a high SINR and high data rate scenario, some resources that would normally be used to transmit RSs can be used to transmit data. Therefore, it is desirable to design a transmitter and receiver scheme that allows for flexible insertion of reference signals according to each user's link conditions. [Means for solving the problem]

[0005] A method for transmitting a discrete Fourier transform-spread orthogonal frequency division multiple access (DFT-S-OFDM) signal including frequency-domain reference symbols is disclosed. The method includes determining to null multiple data symbols before DFT spreading, performing DFT spreading including the determined null data symbols, puncturing an interleaved output of the DFT spreading, inserting reference symbols into the frequency domain of the punctured interleaved DFT-S-OFDM signal, and transmitting the DFT-S-OFDM signal with the inserted reference symbols to a receiver. The transmitted DFT-S-OFDM signal allows the receiver to cancel interference due to puncturing by applying zeros corresponding to the reference symbols to the interleaved input of the DFT despreading and using all outputs of the DFT despreading.

[0006] The number of reference symbols inserted may be based on channel conditions associated with the receiver. For example, if the channel conditions are relatively poor, the number of reference symbols inserted may be increased. A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0007] [Figure 1A] FIG. 1 is a system diagram of an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1B is a system diagram of an example wireless transmit / receive unit (WTRU) that may be used within the communication system shown in FIG. 1A. [Figure 1C] 1B is a system diagram of an example radio access network and an example core network that may be used within the communication system shown in FIG. 1A. [Figure 2]FIG. 1 illustrates an exemplary uplink frame for one subframe according to an embodiment. [Figure 3] FIG. 1 illustrates a general structure for DFT-S-OFDM including multiple DFT spreading blocks. [Figure 4] FIG. 10 is a diagram illustrating an example of resource allocation of reference signals for two users. [Figure 5] 1 illustrates an example of a transmitter and receiver structure for dynamic RS insertion. [Figure 6] FIG. 6 is a diagram showing details of the IC block shown in FIG. 5. [Figure 7] FIG. 1 illustrates different numerologies within a subframe with a single carrier waveform. [Figure 8] FIG. 1 illustrates different numerologies within a subframe having an OFDM waveform. [Figure 9] FIG. 1 is a transmitter and receiver block diagram for DFT-S-OFDM with generalized frequency-domain reference symbols. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1A illustrates an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system providing content, such as voice, data, video, messaging, and broadcast, to multiple wireless users. The communication system 100 enables the multiple wireless users to access such content by sharing system resources, including wireless bandwidth. For example, the communication system 100 may use 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-tailed unique word DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0009] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104, CN 106, public switched telephone network (PSTN) 108, Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and / or “STA,” are configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspot or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain contexts), consumer electronic devices, devices operating in commercial and / or industrial wireless networks, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as UEs.

[0010] The communications system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communications networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a Base Transceiver Station (BTS), a Node B, an eNodeB, a Home Node B, a Home eNodeB, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each shown as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0011] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for wireless service to a particular geographic area, which may be relatively fixed over time or may change. A cell may be further 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 use 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.

[0012] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0013] More specifically, as noted above, the communication system 100 may be a multiple access system and may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using Wideband CDMA (WCDMA). WCDMA may include communication protocols such as High Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed Downlink (DL) Packet Access (HSDPA) and / or High Speed Uplink (UL) Packet Access (HSUPA).

[0014] 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).

[0015] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as New Radio (NR) radio access that may establish an air interface 116 using NR.

[0016] 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 both LTE radio access and NR radio access, e.g., using a dual connectivity (DC) principle. Thus, the radio interface utilized by the WTRUs 102a, 102b, 102c may be characterized by transmissions sent via multiple types of radio access technologies and / or to multiple types of base stations (e.g., eNBs and gNBs).

[0017] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), GSM Evolution Enhanced Data Rates (EDGE), GSM EDGE (GERAN), and the like.

[0018] 1A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a localized area, such as a workplace, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., used by drones), a roadway, and similar locations. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. 1A, the base station 114b may have a direct connection to the Internet 110. Therefore, the base station 114b may not need to access the Internet 110 through the CN 106.

[0019] The RAN 104 can communicate with the CN 106, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 can provide call control, charging services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, and / or perform high-level security functions such as user authentication. Although not shown in FIG. 1A , it will be understood that the RAN 104 and / or CN 106 can communicate directly or indirectly with other RATs that use the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also communicate with another RAN (not shown) that uses GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0020] The CN 106 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing 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 Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) in the TCP / IP Internet protocol suite. The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, which may use the same RAT as the RAN 104 or a different RAT.

[0021] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links.) For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that can use cellular-based wireless technology and with a base station 114b that can use IEEE 802 wireless technology.

[0022] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any sub-combination of the foregoing elements and still be consistent with an embodiment.

[0023] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), field programmable gate array (FPGA) circuitry, 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. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0024] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via 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 understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0025] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may use MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0026] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate over multiple RATs, such as, for example, NR and IEEE 802.11.

[0027] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Additionally, the processor 118 may access information from and store data in any type of suitable memory, such as non-removable memory 130 and / or 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 a server or home computer (not shown).

[0028] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for providing power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0029] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or instead of, information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may obtain location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0030] 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 electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game 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, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, a direction sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0031] The WTRU 102 may include a full-duplex radio, in which case the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 and may reduce and / or substantially eliminate self-interference through hardware (e.g., a choke) or signal processing by a processor (e.g., by a separate processor (not shown) or by processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio, in which case the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for the UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0032] 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As mentioned above, the RAN 104 may use E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0033] The RAN 104 may include eNodeBs 140a, 140b, and 140c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 140a, 140b, and 140c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the eNodeBs 140a, 140b, and 140c may implement MIMO technology. Thus, the eNodeB 140a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0034] Each of the eNodeBs 140a, 140b, 140c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. As shown in FIG. 1C, the eNodeBs 140a, 140b, 140c may communicate with one another via an X2 interface.

[0035] 1C may include a mobility management entity (MME) 142, a serving gateway (SGW) 144, and a packet data network (PDN) gateway (or PGW) 146. While each of the foregoing elements is shown as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0036] The MME 142 is connected to each of the eNodeBs 140a, 140b, 140c in the RAN 104 via an S1 interface and may act as a control node. For example, the MME 142 may handle authentication of users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 142 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.

[0037] The SGW 144 may be connected to each of the eNodeBs 140a, 140b, 140c in the RAN 104 via an S1 interface. The SGW 144 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 144 may perform other functions, such as anchoring the user plane during handovers between eNodeBs, triggering paging when DL data becomes available to the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0038] The SGW 144 may be connected to a PGW 146, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0039] 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 communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0040] Although the WTRU is described in Figures 1A-1C as a wireless terminal, it is also contemplated that in some representative embodiments such a terminal may use (e.g., temporarily or permanently) a wired communication interface with the communication network.

[0041] In an exemplary embodiment, the other network 112 may be a WLAN.

[0042] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with that AP. The AP may have access or interface to a distribution system (DS) or to another type of wired / wireless network that carries traffic to and / or from the BSS. Traffic to a STA originating from outside the BSS may arrive and be delivered to the STA through the AP. Traffic originating from a STA to a destination outside the BSS may be sent to the AP to be delivered to the destination. Traffic between STAs within a BSS may be sent, for example, through the AP, where the source STA may send traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between (e.g., directly between) a source and destination STA in a direct link setup (DLS). In some representative embodiments, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, but the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may also be referred to herein as an "ad hoc" mode of communication.

[0043] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, an AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set by signaling. The primary channel may be the operating channel of the BSS and may be used by STAs to establish communication with the AP. In some representative embodiments, for example, in an 802.11 system, carrier sense multiple access with collision avoidance (CSMA / CA) may be implemented. With CSMA / CA, STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may drop out. One STA (e.g., only one station) may transmit in a given BSS at any given time.

[0044] High-throughput (HT) STAs may use 40 MHz-wide channels for communication, for example, by combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz-wide channel.

[0045] A very high throughput (VHT) STA can support channels of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz width. A 40 MHz and / or 80 MHz channel can be formed by combining adjacent 20 MHz channels. A 160 MHz channel can be formed by combining eight adjacent 20 MHz channels or two non-adjacent 80 MHz channels, which can be called an 80+80 configuration. For the 80+80 configuration, after channel coding, the data can be passed through a segment parser that can split the data into two streams. Inverse fast Fourier transform (IFFT) processing and time-domain processing can be performed separately on each stream. The streams can be mapped to two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80+80 configuration are reversed, and the combined data can be sent to the media access control (MAC).

[0046] Sub-1 GHz operating modes are supported in 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah can support meter-type control / machine-type communications, such as MTC devices in macro coverage areas. MTC devices can have limited functionality, including support for (e.g., only) some and / or limited bandwidths. MTC devices can include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0047] WLAN systems that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that can be designated as a primary channel. The primary channel can have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by the STA that supports the smallest bandwidth operating mode among all STAs operating within the BSS. In an 802.11ah example, the primary channel can be 1 MHz wide for STAs (e.g., MTC-type devices) that support (e.g., only) 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) setting can depend on the status of the primary channel. For example, if the primary channel is busy due to a STA transmitting to the AP (which only supports a 1 MHz mode of operation), the entire available frequency band may be considered busy, even though most of the frequency band may remain idle and be available for use.

[0048] In the United States, the available frequency bands that can be used by 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on country regulations.

[0049] The communication system may include a RAN 104 and a CN 106. As mentioned above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using NR radio technology. The RAN 104 may also communicate with the CN 106.

[0050] The RAN 104 may include a gNB (not shown), although it will be understood that the RAN may include any number of gNBs while remaining consistent with an embodiment. The gNBs 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 may implement MIMO technology. For example, the gNBs may utilize beamforming to transmit signals to and / or receive signals from the gNBs. Thus, for example, the gNBs may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs may implement carrier aggregation technology. For example, the gNBs may transmit multiple component carriers to the WTRU 102a. A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In an embodiment, the gNBs may implement Coordinated Multi-Point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from multiple gNBs.

[0051] The WTRUs 102a, 102b, 102c may communicate with the gNB using transmissions associated with 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 the gNB using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., including different numbers of OFDM symbols and / or lasting different lengths of absolute time).

[0052] The gNBs may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c can communicate with the gNBs without further access to other RANs (e.g., eNodeBs 140a, 140b, 140c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c can utilize one or more of the gNBs as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c can communicate with the gNBs using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c can communicate / connect with the gNBs while also communicating / connecting with another RAN, such as the eNodeBs 140a, 140b, 140c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate substantially simultaneously with one or more gNBs and one or more eNodeBs 140a, 140b, 140c. In a non-standalone configuration, the eNodeBs 140a, 140b, 140c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs may provide additional coverage and / or throughput to serve the WTRUs 102a, 102b, 102c.

[0053] Each of the gNBs 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 for network slicing, dual connectivity, interconnection between NR and E-UTRA, routing of user plane data towards the User Plane Function (UPF), routing of control plane information towards the Access and Mobility Management Function (AMF), and the like. As shown in FIG. 1D, the gNBs may communicate with each other via an Xn interface.

[0054] The CN 106 may include at least one AMF, at least one UPF, at least one Session Management Function (SMF), and possibly a Data Network (DN). Although each of the foregoing elements is shown as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0055] The AMF may be connected to one or more of the gNBs in the RAN 104 via an N2 interface and act as a control node. For example, the AMF may handle authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling various PDU sessions with different requirements), selecting a specific SMF, managing registration areas, terminating NAS signaling, mobility management, and the like. Network slicing may be used by the AMF to customize CN ports for the WTRUs 102a, 102b, 102c based on the type of service utilized. For example, different network slices may be established for different use cases, such as services utilizing ultra-reliable low-latency (URLLC) access, services utilizing enhanced high-capacity mobile broadband (eMBB) access, services for machine-type communications (MTC) access, and / or the like. The AMF may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that use other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0056] The SMF may be connected to the AMF in the CN via an N11 interface. The SMF may also be connected to the UPF in the CN 106 via an N4 interface. The SMF may select and control the UPF and may configure the routing of traffic through the UPF. The SMF may perform other functions such as managing and assigning IP addresses for UEs, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, and the like. PDU session types may be IP-based, non-IP-based, Ethernet-based, and the like.

[0057] The UPF, which may be connected to one or more of the gNBs in the RAN 104 via an N3 interface, may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks such as the Internet 110 to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF may perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0058] The CN 106 may facilitate communication with other networks. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local data network (DN) via the UPF by an N3 interface to the UPF and an N6 interface between the UPF and the DN.

[0059] 1A-1C, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-102d, base stations 114a-114b, eNodeBs 140a-140c, MMEs 142, SGWs 144, PGWs 146, gNBs, AMFs, UPFs, SMFs, DNs, and / or any other devices 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 functionality.

[0060] The emulation device may be designed to perform one or more tests of other devices in a laboratory environment and / or an operator network environment. For example, one or more emulation devices may perform one or more or all functions but be fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. One or more emulation devices may perform one or more or all functions but be temporarily implemented and / or deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device to perform testing and / or may perform testing using wireless communication over the air.

[0061] The one or more emulation devices may perform one or more, including all, functions but are not implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a test lab and / or in a test scenario in an undeployed (e.g., test) wired and / or wireless communication network to perform testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, e.g., one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0062] Figure 2 provides an example of an LTE uplink frame format for one subframe. The LTE uplink uses SC-FDMA-based DFT-s-OFDM modulation. Similar to the downlink (DL) in LTE, each subframe, or transmission time interval (TTI), for the UL is partitioned into 14 symbols (including a cyclic prefix (CP)), and the entire system bandwidth is shared by users scheduled for UL transmission. Frequency domain resources (RBs) at the edge of the system bandwidth are used to transmit the control channel (PUCCH) and its reference channel (PUCCH RS). The remainder of the bandwidth is used to transmit the data channel (PUSCH) or the reference channel (PUSCH RS). For example, in Figure 2, the fourth and eleventh symbols are dedicated to the PUSCH RS, which can be used for channel estimation at the receiver, while the remaining symbols are used for the PUSCH.

[0063] 3 shows an exemplary structure for implementing DFT-S-OFDM, in which multiple DFT spreading blocks have a waveform structure. In conventional CP DFT-S-OFDM (sometimes called SC-FDMA with multiple access), data symbols are first spread by a DFT block and then mapped to the input of an IDFT block. To avoid inter-symbol interference (ISI) and enable one-tap frequency-domain equalization (FDE) at the receiver, a CP is added to the beginning of the symbol.

[0064] DFT-S-OFDM is an example of a precoded OFDM scheme, where DFT-based precoding is used to reduce the PAPR. DFT-S-OFDM also upsamples data symbols by a factor equal to the ratio of IDFT to DFT block sizes, and applies circular pulse shaping using a Dirichlet sinc function before CP extension. The advantage of DFT-S-OFDM is that it exhibits a lower PAPR than regular CP-OFDM symbols.

[0065] In Figure 3, the DFT block 305 is used to spread the input data d. Generally, it is desirable to have a DFT block per user to minimize or reduce PARP. The spread data is then mapped to subcarriers and sent to the IDFT block at 310. A cyclic prefix (CP) is then added to the output of the IDFT block 310 at 315.

[0066] After a set of resources (e.g., a resource block) is allocated to a WTRU, the WTRU may select or be informed to use some resource elements in the allocated set of resources to send reference signals in a subframe. For example, each user may use some subcarriers in an OFDM / DFT-S-OFDM symbol for RS and may use the remaining subcarriers to transmit DFT-spread data symbols. The number and time of resource elements may be specific to each user, and thus different users may use different numbers of resource elements at different times to transmit their RSs.

[0067] In the embodiment shown in Figure 4, two users are assigned for uplink transmission, and each user is granted a portion of the system bandwidth. Reference signals (shaded elements) are used between these two users in different patterns on different symbols. The channel condition from the first user (user 1) to the eNB is good enough, so only a few reference symbols are needed to achieve reliable channel estimation. On the other hand, for user 2, the channel is very fast or noisy, so more reference symbols are desirable to achieve more reliable channel estimation. To achieve dynamic allocation of reference signals for DFT-s-OFDM, special DFT-S-OFDM symbols can be used.

[0068] FIG. 5 shows an exemplary transmitter 510 and receiver 560 structure capable of transmitting and receiving the proposed special DFT-S-OFDM symbol. The transmitter 510 (e.g., a UE) may have K DFT blocks, each with a size M 518. K M2 reference symbols (or pilots) need to be transmitted in the frequency domain, i.e., at the input of the IDFT operation 520. To achieve this, the M2 input 523 of the DFT block may be set to zero to enable interference cancellation, and the M1 input 518 may be a modulated data symbol, where M1 + M2 = M. The positions of the zero symbols and data symbols may be randomized and may differ from those shown in this figure. The positions of the zero samples may be selected so that the receiver observes at least M3 + 1 samples. At the output of each DFT block, every other M3 sample may be discarded and replaced by a reference symbol 530, where M3 = M1 / M2. This can be done by puncturing the interleaved output. For example, one or more outputs 525 of the DFT block can be punctured, and each punctured output can be replaced with an RS symbol. The punctured outputs are selected to have an interleaved pattern (e.g., every nth output is selected (n=M3)).

[0069] After replacing these samples with RS symbols, the new vector is sent to the input of the IDFT block 520. For example, if M=8 and M2=2, then for 8 subcarriers, reference symbols {r1, r2} are needed. Then the input of the DFT block can be {d1, d2,..., d6, 0, 0} (in this case M1=6). If {x1, x2,..., x8} is the output of the DFT, then:

[0070]

number

[0071] After discarding every other DFT output and replacing them with {r1, r2}, {r1, x2, x3, x4, r2, x6, x7, x8} is obtained, which is sent to the IDFT block to generate the time-domain signal. Note that reference symbols can also be inserted with an offset, e.g., {x1, r1, x3, x4, x5, r2, x7, x8} when S=1. Finally, a CP 535 is added to the output of the IDFT block 520.

[0072] At the receiver side 560, up to the IDFT operation 565, the signal processing is similar to that of a receiver for a DFT-S-OFDM signal. At the output of the DFT block, the subcarriers carrying the reference signal can be used for channel estimation. In addition, if the discarded subcarriers at the transmitter side are not replaced by a reference signal (i.e., replaced by zeros), the corresponding subcarriers at the receiver's DFT output 570 can be used for noise or interference power estimation.

[0073] Since some of the DFT block outputs are replaced with reference symbols or pilots at the transmitter side, the output of the IDFT at the receiver side is interfered with due to the "nulling" operation 575. However, that interference can be recovered from the M2 output 577 of the IDFT block and used to cancel the interference at other outputs of the IDFT block. This process can be performed in the "IC" block 580. As an example, the structure of the IC block 580 is given in Figure 6 for zero offset (i.e., S = 0). The IC block 580 can also be improved using an iterative receiver architecture.

[0074] In another exemplary embodiment, the reference symbol r shown in FIG. ij can also be replaced by data symbols if some data symbols need to be transmitted in the frequency domain. Thus, the system architecture shown in Figure 5 allows for simultaneous transmission of DFT-S-OFDM and OFDM signals.

[0075] In another embodiment, consider a single-user scenario consisting of a transmitter and a receiver communicating over a wireless channel. The data symbols transmitted within one DFT-s-OFDM symbol are represented by the vector

[0076]

number

[0077] where N d is the number of data symbols. First, in the basic DFT-s-OFDM, the data symbols are represented by the mapping matrix

[0078]

number

[0079] Using

[0080]

number

[0081] where M is the DFT size, and in the special case, M=N d The output of the DFT is then converted into another mapping matrix

[0082]

number

[0083] Without loss of generality, the mapping matrix M f can be configured to allocate M localized or interleaved subcarriers to achieve low PAPR. Finally, the matrix M f The output of x=F H M fDM t d Equation (1) Like, F H is converted to the time domain by

[0084]

number

[0085] is the inverse DET (IDFT) matrix, and N is the number of subcarriers.

[0086] The channel impulse response (CIR) between the transmitter and receiver is expressed as a vector h=[h0h1···h L ], where L+1 is the number of taps. Assuming the size of the cyclic prefix is greater than L, the received signal vector y is y=Hx+n Equation (2) In the formula,

[0087]

number

[0088] is a circular convolution matrix that models the interaction between the transmitted signal x and the channel h, and

[0089]

number

[0090] is the variance δ 2 is additive white Gaussian noise (AWGN) with

[0091] At the receiver, the operations applied at the transmitter are reversed by taking into account the effects of the multipath channel.

[0092]

number

[0093] where:

[0094]

number

[0095] is the estimated data symbol vector, and

[0096]

number

[0097] is an equalizer that removes the effects of the multipath channel. The equalizer Q is a diagonal matrix and can be derived using the minimum mean square error (MMSE) criterion.

[0098] As can be seen in equation (1), the data symbols are spread across frequency by the matrix D in DFT-s-OFDM. Therefore, the traditional DFT-s-OFDM is H In the M-dimensional subspace spanning M columns of , the RS can be transmitted using a separate DFT-s-OFDM symbol by using a fixed sequence (e.g., a Zadoff-Chu sequence as in LTE) to allow the receiver to estimate the channel. However, since the number of estimated coefficients required to extrapolate the channel frequency response can be significantly less than M, employing two separate DFT-s-OFDM symbols significantly reduces the data rate.

[0099] To insert RSs in some frequency tones, different strategies can be followed, including the following: One option is to puncture information in the frequency domain by exploiting the redundancy introduced by channel coding. However, within one symbol after puncturing, the number of unknowns, i.e., N d(=M) is the number of things observed, i.e., M - N P is more than, i.e., N d = M > M - N P , where N P > 0 is the number of punctured samples at the frequency, which means that a DFT-s-OFDM signal that can be restored by the receiver cannot be obtained.

[0100] In another option, the number of data symbols can be reduced to N d < M, and the size of D can be changed from M to N so as to accommodate the reference symbols in the M-dimensional subspace. However, reference symbols are generally not required for all symbols within a frame or subframe. Therefore, this option creates a need to use variable-size DFT blocks at both the transmitter and the receiver and may not be suitable for radix-2 FFT implementations. d In the third option, the number of unknowns is made less than or equal to the number of things observed after puncturing, i.e., N

[0101] ≦ M - N d by reducing the number of data symbols N P ≦ M, while maintaining the DFT size at M. This option does not increase the complexity of the transmitter. However, puncturing implicitly causes interference to the data symbols, and it is not straightforward to recover the data symbols using a low-complexity receiver. In the following description, this problem is overcome, and it is shown that by using a specific puncturing pattern and inserting zeros at several positions before the DFT spreading block at the transmitter, the data symbols can be recovered using a low-complexity receiver. d Figure 7 shows an example of a transmitter 710 and describes a receiver 760 for generalized DFT-S-OFDM with frequency-domain reference symbols. In this scheme, after puncturing N

[0102] samples at the frequency, the number of things observed is made greater than or equal to the number of unknowns, i.e., N P ​z =MN d ≧N p Null symbols are introduced 715 before the DFT spreading 720. A puncturing operation 730 punctures N symbols at the output of the DFT 720 with an offset. I Considering that every other symbol is punctured, the matrix

[0103]

number

[0104] Due to its periodic structure, the matrix P can be expressed as

[0105]

number

[0106] where:

[0107]

number

[0108] and N i +1 is an integer multiple of M. Without loss of generality, the punctured vector is P c l To fit the frequency domain reference symbol denoted by the nulling matrix

[0109]

number

[0110] By N PThe matrix N is mapped to another vector in M-dimensional space by inserting zeros (740). The reference symbols can be uniformly distributed in frequency (750) by the IDFT block (750) to improve the channel estimation performance at the receiver. In this case, the matrix N can be

[0111]

number

[0112] can be selected as. The whole sending operation is finally

[0113]

number

[0114] where:

[0115]

number

[0116] After puncturing, the energy of x is d CP can be added before transmitting the symbol (755).

[0117] As discussed above, the puncturing operation implicitly distorts the output of the DFT spreading, causing significant interference to the data symbols. The interference to the data and null symbols is given by r=D H P H PDd e -d e Formula (7) where:

[0118]

number

[0119] are the mapped data symbols,

[0120]

number

[0121] and

[0122]

number

[0123] is the interference vector. The interference vector is not arbitrary, but is the N I Every other output is nulled. Using the lemma below, we can obtain the structure of the interference vector r.

[0124] Lemma 1, given below, has two important consequences. First, by using Lemma 1, the k-th element of vector r is

[0125]

number

[0126] and

[0127]

number

[0128] Second, the degrees of freedom of the interference vector r are

[0129]

number

[0130] N as P Therefore, p kN of r corresponding to samples within one period of P Observe only the individual elements,

[0131]

number

[0132] We can regenerate vector r by inferring the remainder of vector r using the relationship t The null symbol position is at least p k Therefore, Lemma 1 clarifies where to insert null symbols so that the receiver can recover the data symbols without any distortion. For example, if M=8, S=0, and N P = 2, and the input of the DFT block is (d1, d2, , d6, 0, 0), (i.e., N z =2, M t Suppose we choose the inputs of the DFT block so that (x1, x2, . . . , x8) is the output of the DFT. N I After discarding every x = 4 DFT output and replacing them by (c1, c2), we get {c1, x2, x3, x4, c2, x6, x7, x8}, which is sent to the IDFT block 750 to generate the time domain signal. At the receiver side, at the output of the IDFT block, there are only 6 samples related to the data symbols. Neglecting the effect of noise for clarity, and using Lemma 1, the equalized vector d e The IDFT of is (d1+p1, d2+p2, d3+p1, , d5+p1, d6+p2, p1, p2), where the last two samples are the interference vector r and p k =p k+2 On the other hand, choosing the data vector as (0, d1, 0, d2, . . . , d6) means that after puncturing, the first and third samples carry the same interfering sample, and the receiver cannot regenerate r.

[0133] At the receiver side 760, a frequency domain unmapping operation is performed, i.e.

[0134]

number

[0135] Up to 763, the signal processing is the same for both the previous DFT-s-OFDM and the proposed scheme described herein. Contrary to the previous DFT-s-OFDM, the subcarriers carrying the reference signal at the output of the DFT can be used for channel estimation using the proposed scheme (CHEST) 765. Using the estimated channel, the subcarriers carrying data are first

[0136]

number

[0137] The symbols at the output of the equalizer are then equalized by P H 775 to the input of the IDFT. H The output of the 780 is

[0138]

number

[0139] where:

[0140]

number

[0141] is the received vector including the effects of noise, equalization, and puncturing. Considering the structure of the interference due to puncturing, a simple method to recover the data symbols is

[0142]

number

[0143] where:

[0144]

number

[0145] and

[0146]

number

[0147] is M t =[M t,d M t,r ] and M t is a submatrix of

[0148]

number

[0149] is shown by Lemma 1

[0150]

number

[0151] and

[0152]

number

[0153] is the reconstruction matrix that calculates the distortion due to puncturing based on the relationship t =I M When R is

[0154]

number

[0155] which substantially simplifies the receiver structure. For example, d e is (d1+p1, d2+p2, d3+p1, , d5+p1, d6+p2, p1, p2), then R will take the last two samples as N I = 3 times, and the repeated vector is expressed as in equation (9):

[0156]

number

[0157] The data symbols can be recovered by subtracting the remaining samples from the remainder of the sample set.

[0158] While the method discussed above allows for a low-complexity receiver, it increases the noise by 3 dB due to the addition of two noisy observations per equation (9). One effective way to mitigate that noise increase is to use an iterative receiver, which aims to remove the noise in the second part of equation (9), i.e., the distortion caused by puncturing. To this end, for the iteration, the data symbols are

[0159]

number

[0160] where:

[0161]

number

[0162] The estimated data symbols

[0163]

number

[0164] is then mapped to the nearest symbol in the constellation by a nonlinear function f(·), i.e., demodulated, and

[0165]

number

[0166] teeth,

[0167]

number

[0168] and prepare for the next iteration.

[0169]

number

[0170] teeth,

[0171]

number

[0172] Since it is generated after the decision is made by

[0173]

number

[0174] This leads to a good estimate of

[0175] The proposed scheme described in this specification is based on the puncturing pattern, the number of reference signals NP , the number of null symbols N Z It is important to emphasize that the receiver structure discussed above derives several conditions on the N-th order of the DFT with offset S. i Second, we take advantage of the fact that every other output is punctured. Z ≧N P must be maintained, and N at the input of the DFT-diffusion block Z The pattern of null symbols in should capture at least one period of distortion due to puncturing to yield a recoverable DFT-s-OFDM symbol. One simple way to do so is to Z The next step is to consider the adjacent null symbols of

[0176] There is further room for improving receiver performance. For example, one simple way to improve receiver performance is to increase the number of null symbols more than the number of punctured symbols, i.e., N Z >N P In this case, the receiver can combine the samples to compute a more reliable interference vector at the expense of reduced spectral efficiency. The receiver structure described above can also be improved by including a channel coding decoder along with demodulation in the feedback branch.

[0177] Without loss of generality, the scheme described herein can be used for multiple DFT blocks. In addition, if the discarded subcarriers at the transmitter side are not replaced by RS (i.e., replaced with zeros), the corresponding subcarriers in the receiver's DFT output can also be used for noise or interference power estimation.

[0178] As stated above, Lemma 1 is stated as follows: Lemma 1 (Periodic Interference): (X n ) for size n=0, 1, . . . , M-1

[0179]

number

[0180] and (Y n )of,

[0181]

number

[0182] With the offset of S, (X n ) elements

[0183]

number

[0184] Let Y be another sequence obtained by zeroing every other n It is possible to decompose the IDFT of y k =x k +r k , where n=0,···,M-1 Equation (13) In the formula, (y k ) is (Y n ), the IDFT of (x k ) is (X n ) and (r k ) for k=0, , M-1

[0185]

number

[0186] is a sequence of size M given by (p k )teeth,

[0187]

number

[0188] is a periodic sequence with period

[0189] Sequence (Y n ) elements are Y n =X n +R n Formula (14) As in, the auxiliary sequence (R n ) where:

[0190]

number

[0191] Since the IDFT operation is linear, (Y n The IDFT of (y k )=(x k )+(r k ), where (r k ) is (R n ) is the IDFT of (r k ) elements are

[0192]

number

[0193] where (S m )teeth,

[0194]

number

[0195] against

[0196]

number

[0197] In Equation 16, (a) is

[0198]

number

[0199] When is not an integer, r n is true because is zero, and (b) is an exponential function

[0200]

number

[0201] is true due to the periodicity of

[0202]

number

[0203] This becomes:

[0204] In some scenarios, when a single-carrier waveform such as DFT-s-OFDM is used, all of the subcarriers within the allocated bandwidth may be used to transmit reference signal (pilot) symbols. In such a transmission mode, the number of waveform symbols (e.g., DFT-s-OFDM symbols) carrying reference signals can be dynamically changed. As an example, in LTE uplink data transmission, one subframe consists of 14 DFT-s-OFDM symbols, and two of these symbols are used to transmit pilots. If the WTRU requires better channel estimation, for example due to mobility, the number of symbols for RS transmission can be increased from two to three or more.

[0205] Varying the number of pilot symbols changes the amount of resources allocated to data transmission. As a result, the transport block size and / or the coding rate may need to be modified. In one solution, the number and location of pilot symbols can be configured by a central controller, such as an eNB, and / or dynamically signaled in a control channel for each transmission. For each possible number of pilot symbols, a corresponding value for the transport block size can be defined.

[0206] Figure 8 shows an example subframe in which some of the symbols transmitted within a particular time interval are generated using a different waveform numerology than the remaining symbols. In Figure 8, the time interval used for the first PUSCH symbol 810 is used to transmit two DFT-s-OFDM symbols, where each DFT-s-OFDM symbol has half the symbol duration of the remaining symbols. One of the two new DFT-s-OFDM symbols is used for reference signal transmission, while the other symbol is used for data transmission.

[0207] When the waveform is not a single-carrier waveform, e.g., OFDM, it may be possible to dynamically or semi-statically configure some subcarriers of some OFDM symbols as data or pilot subcarriers. Subcarriers used for data transmission can be configured to carry reference symbols, or subcarriers used for pilot transmission can be configured to carry data. It is possible to transmit several OFDM symbols within a particular time interval, some of which can be generated by using a different waveform and numerology than the remaining OFDM symbols.

[0208] FIG. 9 provides an example in which, in addition to the subcarriers originally configured to transmit reference symbols, some subcarriers in the last OFDM symbol of a subframe are configured to transmit reference symbols. Furthermore, the first two OFDM symbols have half the duration of the remaining OFDM symbols, and some subcarriers in the first OFDM symbol are also configured for reference symbol transmission. Note that due to different waveform numerology, the first two OFDM symbols may have a larger subcarrier spacing than the remaining OFDM symbols. Furthermore, although a cyclic prefix (CP) is not shown in the figure, a CP can precede each OFDM symbol. These techniques can be applied to other multicarrier waveforms, such as windowed OFDM, filtered OFDM, filter bank multicarrier, and the like.

[0209] Although functions and elements are described above in particular combinations, those skilled in the art will understand that each function or element can be used alone or in any combination with the other functions and elements. Furthermore, the methods described herein can be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution on 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, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, internal hard and removable disks, magnetic media such as magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor associated with software can be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer. [Explanation of symbols]

[0210] 510 Transmitter 520 IDFT operations 523 input 525 output 530 Reference Symbol 560 receiver 565 IDFT operations 570 DFT output 575 Calculation 577 Output 580 IC Block

Claims

1. transmitting, by a base station, dynamic scheduling information to a wireless transmit / receive unit (WTRU), the dynamic scheduling information assigning Discrete Fourier Transform Spreading-Orthogonal Frequency Division Multiplexing (DFTS-OFDM) symbols to be used for reference signal symbols for a first Physical Uplink Shared Channel (PUSCH) transmission; receiving, by the base station, the first PUSCH transmission using DFTS-OFDM with a reference signal in the assigned DFTS-OFDM symbols used for the reference signal symbols; transmitting, by the base station, second dynamic scheduling information to the WTRU, allocating DFTS-OFDM symbols to be used for reference signal symbols for a second PUSCH transmission; receiving, by the base station, the second PUSCH transmission using DFTS-OFDM having reference signals in the DFTS-OFDM symbols allocated by the second dynamic scheduling information, wherein symbols and symbol times to be used for the reference signals differ between the dynamic scheduling information and the second dynamic scheduling information; A method comprising:

2. 2. The method of claim 1, wherein the base station is a gNodeB and the WTRU is a New Radio (NR) user equipment (UE).

3. 10. The method of claim 1, wherein the second PUSCH transmission includes nulled subcarriers in symbols used to transmit reference signals.

4. A base station, a transmitter configured to transmit dynamic scheduling information to a wireless transmit / receive unit (WTRU), the dynamic scheduling information assigning discrete Fourier transform spreading-orthogonal frequency division multiplexing (DFTS-OFDM) symbols to be used for reference signal symbols for a first physical uplink shared channel (PUSCH) transmission; and a receiver configured to receive the first PUSCH transmission using DFTS-OFDM with a reference signal in the assigned DFTS-OFDM symbols to be used for the reference signal symbols; Equipped with The transmitter is further configured to transmit second dynamic scheduling information to the WTRU, the second dynamic scheduling information assigning DFTS-OFDM symbols to be used for reference signal symbols for a second PUSCH transmission; The receiver is further configured to receive the second PUSCH transmission using DFTS-OFDM having a reference signal in the assigned DFTS-OFDM symbol of the second dynamic scheduling information, wherein the symbol and symbol time to be used for the reference signal differ between the dynamic scheduling information and the second dynamic scheduling information. A base station characterized by:

5. 5. The base station of claim 4, wherein the base station is a gNodeB and the WTRU is a New Radio (NR) user equipment (UE).

6. 5. The base station of claim 4, wherein the receiver is configured to receive the second PUSCH transmission with nulled subcarriers in symbols to be used by the WTRU transmitting reference signals.

7. 1. A method performed by a wireless transmit receive unit (WTRU), comprising: receiving first dynamic scheduling information, the first dynamic scheduling information assigning first Discrete Fourier Transform Spreading-Orthogonal Frequency Division Multiplexing (DFTS-OFDM) symbols to be used for reference signal symbols for a first Physical Uplink Shared Channel (PUSCH) transmission; transmitting the first PUSCH transmission using DFTS-OFDM with a reference signal in the assigned first DFTS-OFDM symbol used for the reference signal symbol; receiving second dynamic scheduling information, the second dynamic scheduling information assigning second DFTS-OFDM symbols to be used for reference signal symbols for a second Physical Uplink Shared Channel (PUSCH) transmission; and transmitting the second PUSCH transmission using DFTS-OFDM having a reference signal in the assigned second DFTS-OFDM symbol to be used for the reference signal symbol, wherein the first DFTS-OFDM symbol to be used for the reference signal symbol and the second DFTS-OFDM symbol to be used for the reference signal symbol are different; A method comprising:

8. 8. The method of claim 7, wherein the second PUSCH transmission includes nulled subcarriers in symbols used to transmit reference signals.

9. 8. The method of claim 7, wherein the first dynamic scheduling information includes location information for the first DFTS-OFDM symbol to be used for a reference signal symbol.

Images