Flexible reference signal transmission method using single carrier frequency division multiple access (SC-FDMA) and OFDMA

Abstract

A method for transmitting a discrete Fourier transform (DFT) DFT-S-OFDM signal including frequency domain reference symbols is disclosed. The method includes determining a plurality of data symbols to be null prior to DFT spreading, performing DFT spreading including the determined null data symbols, puncturing interleaved outputs 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 the inserted reference symbols to a receiver. The transmitted DFT-S-OFDM signal enables the receiver to apply zeros corresponding to the reference symbols to interleaved inputs of DFT despreading and to cancel interference due to puncturing by using all outputs of the DFT despreading.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201780060623.X, filed on August 10, 2017, entitled "Flexible Reference Signal Transmission Method Using Single-Carrier Frequency Division Multiple Access (SC-FDMA) and OFDMA", the contents of which are incorporated herein by reference.

[0002] Cross-reference to related applications

[0003] This application claims the benefits of U.S. Provisional Application No. 62 / 373,126, filed August 10, 2016, and U.S. Provisional Application No. 62 / 479,792, filed March 31, 2017, the contents of which are incorporated herein by reference. Background Technology

[0004] In typical single-carrier frequency division multiple access (SC-FDMA) communication, such as that used in LTE uplink transmission, the reference signal (RS) for data transmission is allocated only to two time-domain symbol positions, and data symbols cannot be transmitted at those positions. Regardless of channel conditions, the resource usage overhead is fixed for all users and cannot be dynamically changed based on channel conditions and service requirements. For example, in low SINR and ultra-reliable applications, adding more RS would allow the receiver to estimate the channel more accurately so that data can be detected with a low error rate. On the other hand, in high SINR and high data rate requirements, some resources used for transmitting RS can be additionally used for data transmission. Therefore, it is desirable to design a transmitter and receiver scheme that allows for flexible insertion of reference signals based on the link conditions of each user. Summary of the Invention

[0005] A method for transmitting a Discrete Fourier Transform-Spread-Orthogonal Frequency Division Multiple Access (DFT-S-OFDM) signal including a frequency domain reference symbol is disclosed. The method includes: determining that a plurality of data symbols are empty before DFT spreading; performing DFT spreading including the determined empty data symbols; interleaving the output of the punched DFT spreading; inserting a reference symbol in the frequency domain of the punched and interleaved DFT-S-OFDM signal; and transmitting the DFT-S-OFDM signal with the inserted reference symbol to a receiver. The transmitted DFT-S-OFDM signal enables the receiver to apply zeros corresponding to the reference symbol to the interleaved input of the DFT despreading and to eliminate interference caused by punching by using all outputs of the DFT despreading.

[0006] The number of inserted reference symbols can be based on the channel conditions associated with the receiver. For example, if the channel conditions are relatively poor, the number of inserted reference symbols can be increased. Attached Figure Description

[0007] The invention will be understood in more detail from the following description, which is given by way of example and can be understood in conjunction with the accompanying drawings, wherein:

[0008] Figure 1A It is a system diagram of an example communication system in which one or more of the disclosed embodiments can be implemented;

[0009] Figure 1B This is a system diagram of an example Wireless Transmit / Receive Unit (WTRU), wherein the WTRU can be configured as follows: Figure 1A Used in the communication system shown;

[0010] Figure 1C This is a system diagram of an example radio access network and an example core network, wherein the example core network can be configured as follows: Figure 1A Used in the communication system shown;

[0011] Figure 2 An example uplink frame format of a subframe according to an embodiment is shown;

[0012] Figure 3 A general structure of DFT-S-OFDM including multiple DFT extension blocks is shown;

[0013] Figure 4 An example of resource allocation for reference signals from two users is shown;

[0014] Figure 5 An example of a transmitter and receiver architecture for dynamic RS insertion is shown;

[0015] Figure 6 It shows Figure 5 Details of the IC block shown;

[0016] Figure 7 The different sets of parameters (numerology) within a subframe with a single carrier waveform are shown;

[0017] Figure 8 Different sets of parameters within a subframe with an OFDM waveform are shown; and

[0018] Figure 9 Block diagrams of the transmitter and receiver for DFT-S-OFDM with generalized frequency domain reference symbols are shown. Detailed Implementation

[0019] Figure 1AThis illustration depicts an example communication system 100 in which one or more of the disclosed implementation methods may be implemented. Communication system 100 may be a multi-access system that provides content such as voice, data, video, messages, broadcasts, etc., to multiple wireless users. Communication system 100 enables multiple wireless users to access this content through the sharing of system resources (including wireless bandwidth). For example, 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 Suffix Unique Word DFT-Extended OFDM (ZT UW DTS-sOFDM), Unique Word OFDM (UW-OFDM), Resource Block Filtered OFDM, Filter Bank Multicarrier (FBMC), etc.

[0020] like Figure 1A As shown, the communication 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. However, it is understood that the disclosed embodiments may cover any number of WTRUs, base stations, networks, and / or network elements. Each of the client devices 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless communication environment. As an example, any of WTRUs 102a, 102b, 102c, and 102d may be referred to as a “station” and / or “STA”, may be 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, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, 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 process situations), consumer electronics, devices operating on commercial and / or industrial wireless networks, and so on. Any of WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0021] The communication system 100 may also include base station 114a and / or base station 114b. Each of base stations 114a and 114b may be any type of device configured to wirelessly interact with at least one of WTRUs 102a, 102b, 102c, and 102d to facilitate access to one or more communication networks (e.g., CN 106, Internet 110, and / or Network 112). For example, base stations 114a and 114b may be base transceiver stations (BTS), node B, e-node B, home node B, home e-node B, gNB, NR node B, site controller, access point (AP), wireless router, and similar devices. Although each of base stations 114a and 114b is described as a single element, it is understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0022] Base station 114a may be part of RAN 104, which may also include other base station and / or network elements (not shown), such as site controllers (BSCs), radio network controllers (RNCs), and relay nodes. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in licensed spectrum, in unlicensed spectrum, or in a combination of licensed and unlicensed spectrum. Cells can provide coverage for radio services to a specific geographic area that is relatively fixed or changes over time. Cells may also be divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In another embodiment, base station 114a may use multiple-input multiple-output (MIMO) technology, and thus may use multiple transceivers for each sector of the cell. For example, beamforming can be used to transmit and / or receive signals in a desired spectral direction.

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

[0024] More specifically, as previously described, communication system 100 can be a multiple access system and can use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and similar schemes. For example, base stations 114a and WTRUs 102a, 102b, and 102c in RAN 104 can implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA can include technologies such as High-Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High-Speed ​​Uplink (UL) Packet Access (HSUPA).

[0025] In another embodiment, base station 114a and WTRUs 102a, 102b, 102c may implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may use Long Term Evolution (LTE) and / or LTE-A and / or LTE-APro (LTE-APro) to establish air interface 116.

[0026] In one implementation, base station 114a and WTRUs 102a, 102b, 102c may implement radio technologies such as NR radio access, which may use a new radio (NR) to establish an air interface 116.

[0027] In one implementation, base station 114a and WTRUs 102a, 102b, and 102c can implement multiple radio access technologies. For example, base station 114a and WTRUs 102a, 102b, and 102c can implement LTE radio access and NR radio access together, such as using a dual connectivity (DC) principle. Thus, the air interface utilized by WTRUs 102a, 102b, and 102c can possess the characteristics of multiple types of radio access technologies and / or transmissions to or from multiple types of base stations (e.g., eNB and gNB).

[0028] In other implementations, base station 114a and WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wi-Fi), IEEE 802.16 (i.e., WiMAX), CDMA2000, CDMA20001x, CDMA2000EV-DO, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rate GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0029] For example, Figure 1A Base station 114b can be a wireless router, home node B, home e-node B, or access point, and can use any suitable RAT to facilitate communication connectivity in localized areas such as companies, homes, vehicles, campuses, industrial facilities, air corridors (e.g., used by drones), and roads. In one embodiment, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, base station 114b and client devices 102c, 102d can implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, base station 114b and WTRUs 102c, 102d can use cellular-based RATs (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-APro, NR, etc.) to establish picocell and femtocell cells. Figure 1A As shown, base station 114b can have a direct connection to the Internet 110. Therefore, base station 114b does not need to access the Internet 110 via CN 106.

[0030] RAN 104 can communicate with the core network 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 WTRUs 102a, 102b, 102c, and 102d. Data can have varying Quality of Service (QoS) requirements, such as varying throughput, latency, fault tolerance, reliability, data throughput, mobility, etc. Core network 106 can provide call control, billing services, location-based services, prepaid calling, internet access, video distribution, etc., and / or perform advanced security functions such as user authentication. Although... Figure 1AAs not shown, it is important to understand that RAN 104 and / or CN 106 can communicate directly or indirectly with other RANs, which may use the same RAT as RAN 104 or a different RAT. For example, in addition to connecting to RAN 104, which can use NR radio technology, CN 106 can also communicate with other RANs (not shown) using GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technologies.

[0031] CN 106 can also serve as a gateway for WTRUs 102a, 102b, 102c, and 102d to access PSTN 108, the Internet 110, and / or other networks 112. PSTN 108 may include a circuit-switched telephone network providing Common Old-Style Telephone Service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols, such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) from the TCP / IP network protocol suite. Network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs, which may use the same RAT as RAN 104 or a different RAT.

[0032] Some or all of the WTRUs 102a, 102b, 102c, and 102d in communication system 100 may include multi-mode capabilities (e.g., WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different wireless networks via different communication links). For example, Figure 1A The WTRU 102c shown can be configured to communicate with base station 114a using cellular-based radio technology and with base station 114b using IEEE 802 radio technology.

[0033] Figure 1B This is a system diagram describing the example WTRU 102. (Example:) Figure 1B As shown, WTRU 102 may include a processor 118, a transceiver 120, a transmitting / receiving element 122, a speaker / microphone 124, a keyboard 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a GPS chipset 136, and / or other peripheral devices 138. It should be understood that, while maintaining consistency with the above embodiments, WTRU 102 may include any subset of the aforementioned components.

[0034] 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), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. Processor 118 may perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable WTRU 102 to operate in a wireless environment. Processor 118 may be coupled to transceiver 120, which may be coupled to transmitting / receiving element 122. Although... Figure 1B The processor 118 and transceiver 120 are described as separate components, but it is understood that the processor 118 and transceiver 120 can be integrated together into an electronic package or chip.

[0035] Transmitting / receiving element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via air interface 116. For example, in one embodiment, transmitting / receiving element 122 can be an antenna configured to transmit and / or receive RF signals. In another embodiment, transmitting / receiving element 122 can be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, transmitting / receiving element 122 can be configured to transmit and receive both RF signals and optical signals. It should be understood that transmitting / receiving element 122 can be configured to transmit and / or receive any combination of wireless signals.

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

[0037] Transceiver 120 can be configured to modulate signals to be transmitted by transmitting / receiving element 122 and to demodulate signals received by transmitting / receiving element 122. As described above, WTRU 102 can have multi-mode capability. Thus, for example, transceiver 120 may include multiple transceivers to enable WTRU 102 to communicate via multiple RATs such as NR and IEEE 802.11.

[0038] The processor 118 of WTRU 102 can be coupled to a speaker / microphone 124, a keyboard 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) unit or an organic light-emitting diode (OLED) display unit), and can receive user input data from these devices. The processor 118 can also output data to the speaker / microphone 124, keyboard 126, and / or display / touchpad 128. Furthermore, the processor 118 can access information from any type of suitable memory, and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. Non-removable memory 130 can include random access memory (RAM), readable storage memory (ROM), a hard disk, or any other type of memory storage device. Removable memory 132 can include a Subscriber Identity Module (SIM) card, Memory Stick, Secure Digital (SD) memory card, and similar devices. In other embodiments, the processor 118 can access data from memory not physically located on WTRU 102, such as on a server or home computer (not shown), and store data in such memory.

[0039] The processor 118 can receive power from the power supply 134 and can be configured to distribute power to other components in the WTRU 102 and / or control the power to other components in the WTRU 102. The power supply 134 can be any device suitable for charging the WTRU 102. For example, the power supply 134 may include one or more dry cell batteries (NiCd, NiZn, NiMH, Li-ion, etc.), solar cells, fuel cells, etc.

[0040] 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) about the current location of the WTRU 102. As a supplement to or alternative to the information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via air interface 116, and / or determine its location based on the timing of signals received from two or more adjacent base stations. It should be understood that, consistent with the implementation method, the WTRU 102 may acquire location information using any suitable location determination method.

[0041] The processor 118 can also be coupled to other peripheral devices 138, which may include one or more software and / or hardware modules providing additional features, functionality, and / or wireless or wired connectivity. For example, peripheral devices 138 may include an accelerometer, an electronic compass (e-compass), a satellite transceiver, a digital camera (for photos and / or video), a Universal Serial Bus (USB) interface, a vibration device, a television transceiver, hands-free headphones, etc. Modules, FM radio units, digital music players, media players, video game player modules, internet browsers, virtual reality and / or augmented reality (VR / AR) devices, activity trackers, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor; geolocation sensor; altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor, and / or humidity sensor.

[0042] WTRU 102 may include a full-duplex radio for transmitting and receiving some or all of the signals, which (e.g., are associated with specific subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or analog. The full-duplex radio may include an interference management unit to reduce and / or substantially eliminate self-interference via hardware (e.g., a choke) or via signal processing by a processor (e.g., a separate processor (not shown) or via processor 118). In one embodiment, WTRU 102 may include a half-duplex radio for transmitting and receiving some or all of the signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)).

[0043] Figure 1C This is a system block diagram illustrating RAN 104 and CN 106 according to one embodiment. As described above, RAN 104 can communicate with WTRUs 102a, 102b, and 102c via air interface 116 using E-UTRA radio technology. RAN 104 can also communicate with CN 106.

[0044] RAN 104 may include eNodeBs 140a, 140b, and 140c, although it should be understood that RAN 104 may include any number of eNodeBs while remaining consistent with the implementation. Each eNodeB 140a, 140b, and 140c may include one or more transceivers that communicate with WTRUs 102a, 102b, and 102c via air interface 116. In one implementation, eNodeBs 140a, 140b, and 140c may use MIMO technology. Thus, for example, eNodeB 140a may use multiple antennas to transmit radio signals to and / or receive radio information from WTRU 102a.

[0045] Each of eNodeB 140a, 140b, and 140c can be associated with a specific unit (not shown) and can be configured to process radio resource management decisions, handover decisions, and user scheduling in the UL and / or DL. Figure 1C As shown, nodes B140a, 140b, and 140c can communicate with each other via the X2 interface.

[0046] Figure 1C The CN 106 shown may include a Mobility Management Entity (MME) 142, a Serving Gateway (SGW) 144, and a Packet Data Network (PDN) Gateway (or PGW) 146. Although each of the above elements is described as part of CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0047] The MME 142 can be connected to each of the eNodeBs 140a, 140b, and 140c in RAN 104 via the S1 interface and can act as a control node. For example, the MME 142 can be responsible for authenticating users of WTRUs 102a, 102b, and 102c, bearer activation / deactivation, selecting a specific serving gateway during the initial connection of WTRUs 102a, 102b, and 102c, and so on. The MME 142 can also provide control plane functions for switching between RAN 104 and other RANs (not shown) using other radio technologies (such as GSM and / or WCDMA).

[0048] The SGW 144 can be connected to each of the eNodeBs 140a, 140b, and 140c in RAN 104 via the S1 interface. The SGW 144 typically routes and forwards user data packets to or from WTRUs 102a, 102b, and 102c. The SGW 144 can also perform other functions, such as anchoring the user plane during inter-eNodeB handover, triggering paging when DL data is available for WTRUs 102a, 102b, and 102c, and managing and storing the storage context for WTRUs 102a, 102b, and 102c.

[0049] SGW 144 can also be connected to PGW 146, which can provide WTRU 102a, 102b, 102c with access to a packet-switched network (e.g., Internet 110), thereby facilitating communication between WTRU 102a, 102b, 102c and IP-enabled devices.

[0050] CN 106 can facilitate communication with other networks. For example, CN 106 can provide WTRUs 102a, 102b, and 102c with access to a circuit-switched network (e.g., PSTN 108), thereby facilitating communication between WTRUs 102a, 102b, and 102c and conventional landline communication equipment. For example, CN 106 may include, or can communicate with, an IP gateway (e.g., IP Multimedia Subsystem (IMS) service) serving as an interface between CN 106 and PSTN 108. Additionally, CN 106 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0051] Despite Figure 1A-1C The document describes the WTRU as a wireless terminal, and it is conceivable that, in some representative embodiments, such a terminal may be used (e.g., temporarily or permanently) to a wired communication interface to a communication network.

[0052] In a representative embodiment, another network 112 may be a WLAN.

[0053] In an Infrastructure Basic Services Set (BSS) mode, a WLAN may have an Access Point (AP) for the BSS and one or more Stations (STAs) associated with the AP. The AP may have access or an interface to a Distribution System (DS) or other type of wired / wireless network that carries services into and / or out of the BSS. Services sent from outside the BSS to a STA can reach the AP and be delivered to the STA. Services sent from a STA to a destination outside the BSS may be sent to the AP and delivered to the corresponding destination. Services between STAs within the BSS can be sent via the AP; for example, a source STA can send a service to the AP, and the AP can deliver that service to the destination STA. Services between STAs within the BSS may be considered and / or referred to as peering services. Peering services can be sent between (e.g., directly at) the source and destination STAs via Direct Link Establishment (DLS). In some representative embodiments, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using Standalone BSS (IBSS) mode may not have an access point (AP), and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. Here, the IBSS communication mode may sometimes be referred to as an "ad-hoc" communication mode.

[0054] When operating in 802.11ac infrastructure mode or a similar mode, the AP can transmit beacons on a fixed channel, such as the primary channel. The primary channel can be of fixed width (e.g., a 20 MHz wide bandwidth) or dynamically set via signaling. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative embodiments, Carrier Sense Multiple Access (CSMA / CA) with collision avoidance can be implemented, for example, in an 802.11 system. For CSMA / CA, STAs including the AP (e.g., each STA) can be aware of the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, that STA can go out of service. A single STA (e.g., only one station) can transmit at any given time within a given BSS.

[0055] High-throughput (HT) STAs can communicate using a 40MHz wide channel, for example, by combining a 20MHz main channel with adjacent or non-adjacent 20MHz channels to form a 40MHz wide channel.

[0056] Ultra-High Throughput (VHT) STAs can support channels with widths of 20MHz, 40MHz, 80MHz, and / or 160MHz. 40MHz and / or 80MHz channels can be formed by combining consecutive 20MHz channels. A 160MHz channel can be formed by combining eight consecutive 20MHz channels or by combining two non-consecutive 80MHz channels (which can be referred to as an 80+80 configuration). For the 80+80 configuration, the channel-coded data is passed through a segment resolver that splits the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing can be performed on each stream separately. The streams can be mapped to the two 80MHz channels mentioned above, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the operation of the 80+80 configuration can be reversed, and the combined data can be sent to the Media Access Control (MAC).

[0057] 802.11af and 802.11ah support Sub-1GHz operating modes. Compared to 802.11af and 802.11ah used in 802.11n and 802.11ac, both have reduced channel operating bandwidth and carrier capacity. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, while 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah can support meter-type control / machine-type communication for MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support (e.g., only support) certain and / or limited bandwidths. MTC devices may include batteries with a battery life exceeding a threshold (e.g., to maintain very long battery life).

[0058] 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 the primary channel. The primary channel can have a bandwidth equal to the maximum 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 among all STAs operating in a BSS that supports a minimum bandwidth operating mode. In the 802.11ah example, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes, the primary channel can be 1MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. For example, if the primary channel is busy, for example due to an STA (which only supports a 1MHz operating mode), the entire available band can be considered busy even if most of the frequency band sent to the AP remains idle and potentially available.

[0059] In the United States, the available frequency bands for 802.11ah are from 902MHz to 928MHz. In South Korea, the available bands are from 917.5MHz to 923.5MHz. In Japan, the available bands are from 916.5MHz to 927.5MHz. Depending on the country code, the total available bandwidth for 802.11ah is from 6MHz to 26MHz.

[0060] This section describes another example of a communication system comprising RAN 104 and CN 106. As described above, RAN 104 can use NR radio technology to communicate with WTRUs 102a, 102b, and 102c via air interface 116. RAN 104 can also communicate with CN 106.

[0061] RAN 104 may include gNBs (not shown), but it should be understood that RAN may include any number of gNBs while remaining consistent with the embodiments. Each gNB may include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In one embodiment, the gNB may implement MIMO technology. For example, the gNB may utilize beamforming to transmit signals to and / or receive signals from the gNB. Thus, for example, the gNB may use multiple antennas to transmit and / or receive radio signals from WTRU 102a. In one embodiment, the gNB may implement carrier aggregation technology. For example, the gNB may transmit multiple component carriers to WTRU 102a. A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In one embodiment, the gNB may implement Coordinated Multipoint (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from multiple gNBs.

[0062] WTRUs 102a, 102b, and 102c can communicate with the gNB using transmissions associated with a scalable set of parameters. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing can vary for different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRUs 102a, 102b, and 102c can communicate with the gNB using subframes or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute durations).

[0063] The gNB can be configured to communicate with WTRUs 102a, 102b, and 102c in standalone and / or non-standalone configurations. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with the gNB without accessing other RANs (e.g., eNode-B 140a, 140b, and 140c). In standalone configuration, WTRUs 102a, 102b, and 102c can utilize one or more of the gNBs as mobility anchors. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs using signals in unlicensed frequency bands. In non-standalone configuration, WTRUs 102a, 102b, and 102c can communicate / connect with the gNBs while also communicating / connecting with another RAN such as eNode-B 140a, 140b, and 140c. For example, WTRU102a, 102b, and 102c can implement a DC principle that allows them to communicate substantially simultaneously with one or more gNBs and one or more eNode-Bs 140a, 140b, and 140c. In a non-standalone configuration, eNode-Bs 140a, 140b, and 140c can serve as mobility anchors for WTRU102a, 102b, and 102c, and the gNBs can provide additional coverage and / or throughput for serving WTRU102a, 102b, and 102c.

[0064] Each gNB can be associated with a specific cell and can be configured to handle the following: radio resource management decisions, handover decisions, user scheduling in UL and / or DL, network slicing support, dual connectivity, interoperability between NR and E-UTRA, routing user plane data to User Plane Functions (UPFs), and routing control plane information to Access and Mobility Management Functions (AMFs), etc. As shown here, gNBs can communicate with each other via the Xn interface.

[0065] 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). While the above elements may be part of CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0066] The AMF can connect to one or more gNBs in RAN 104 via the N2 interface and can act as a control node. For example, the AMF can be responsible for authenticating users of WTRUs 102a, 102b, and 102c, supporting network slicing (e.g., handling different PDU sessions with different needs), selecting specific SMFs, managing registration areas, terminating NAS signaling, mobility management, etc. The AMF can use network slicing to customize CN support for WTRUs 102a, 102b, and 102c based on the type of service being used. For example, different network slices can 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, Machine Type Communication (MTC) access, and / or the like. The AMF can provide control plane functions for handover between RAN 104 and other RANs using other radio technologies such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access (e.g., WiFi).

[0067] The SMF can connect to the AMF in the CN via the N11 interface. The SMF can also connect to the UPF in CN 106 via the N4 interface. The SMF can select and control the UPF and configure service routes through the UPF. The SMF can perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. PDU session types can be IP-based, non-IP-based, Ethernet-based, etc.

[0068] The UPF can connect to one or more gNBs in RAN 104 via the N3 interface, providing WTRUs 102a, 102b, and 102c with access to packet-switched networks (such as Internet 110) to facilitate communication between WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF can 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, and providing mobility anchoring.

[0069] CN 106 can facilitate communication with other networks. For example, CN 106 may include, and communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 106 and PSTN 108. Furthermore, CN can provide WTRUs 102a, 102b, and 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, WTRUs 102a, 102b, and 102c can be connected to the DN via the UPF's N3 interface and the N6 interface between the UPF and the local data network (DN).

[0070] As stated herein and taking into account Figure 1A-1C as well as Figure 1A-1C The corresponding descriptions herein, relating to one or more or all of the functions described herein: WTRU 102a-d, base station 114a-b, eNodeB 140a-c, MME 142, SGW 144, PGW 146, the gNB(one or more), the AMF(one or more), the UPF(one or more), the SMF(one or more), the DN(one or more), and / or other devices described herein, may be performed by one or more emulation devices. An emulation device may be a device configured to emulate one or more or all of the functions described herein. For example, an emulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0071] Simulation devices can be designed to perform one or more tests on other devices in laboratory and / or carrier network environments. For example, one or more simulation devices can perform one or more or all of their functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. One or more simulation devices can perform one or more or all of their functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. For testing and / or testing using over-the-air wireless communication, the simulation device can be directly coupled to another device.

[0072] One or more emulation devices can perform one or more functions (including all functions) without being implemented / deployed as part of a wired and / or wireless communication network. For example, emulation devices can be used in test scenarios within a test laboratory and / or a non-deployed (e.g., tested) wired and / or wireless communication network to test one or more components. One or more emulation devices can be test devices. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which may include one or more antennas) can be used by emulation devices to transmit and / or receive data.

[0073] Figure 2 An example of an LTE uplink frame format for a subframe is provided. The LTE uplink uses DFT-s-OFDM modulation based on the SC-FDMA scheme. Similar to the downlink (DL) in LTE, each subframe or transmission time interval (TTI) for UL is divided into 14 symbols (including the cyclic prefix (CP)), and the entire system bandwidth is shared by scheduled users 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 PUCCHRS. The remaining bandwidth is used to transmit the data channel (PUSCH) or reference channel (PUSCH RS). For example, in Figure 2 In the diagram, symbols 4 and 11 are dedicated to PUSCH RS, which can be used for channel estimation at the receiver, while the remaining symbols are used for PUSCH.

[0074] Figure 3 An example structure for performing DFT-S-OFDM is shown, in which multiple DFT expansion blocks are incorporated into the waveform structure. In conventional CP DFT-S-OFDM (sometimes referred to as SC-FDMA with multiple accesses), data symbols are first expanded with DFT blocks and then mapped to the inputs of IDFT blocks. To avoid inter-symbol interference (ISI) and to allow single-tap frequency domain equalization (FDE) at the receiver, CP is added to the beginning of the symbol.

[0075] DFT-S-OFDM is an example of a pre-coding OFDM scheme where precoding using the DFT aims to reduce PAPR. tDFT-S-OFDM is also an example of a scheme that upsamples data symbols by a factor equal to the ratio of the IDFT and DFT block sizes, and applies cyclic impulse shaping using the Dirichlet sinc function before CP expansion. The advantage of DFT-S-OFDM is that it has a lower PAPR than ordinary CP-OFDM symbols.

[0076] exist Figure 3In this process, DFT block 305 is used to expand the input data d. Typically, it is desirable to have a DFT block for each user to minimize or reduce PARP. The expanded data is then mapped to subcarriers and sent to the IDFT block at 310. Next, a cyclic prefix (CP) is added to the output of IDFT block 310 at 315.

[0077] After a set of resources (e.g., resource blocks) is allocated to the WTRU, the WTRU can choose or be signaled to use some resource elements from the allocated resource set to transmit a reference signal in a subframe. For example, each user can use several subcarriers within an OFDM / DFT-S-OFDM symbol for the RS, and the remaining subcarriers can be used to transmit DFT spread data symbols. The number of resource elements and the time can be specific to each user, allowing different users to use different numbers of resource elements to transmit their RS at different times.

[0078] exist Figure 4 In the illustrated embodiment, two users are assigned for uplink transmission, and each user is granted a portion of the system bandwidth. Reference signals (shaded elements) are used in different patterns on different symbols between the two users. The channel state from the first user (User 1) to the eNB may be good enough, thus requiring only a few reference symbols for reliable channel estimation. For User 2, however, the channel may change rapidly or be noisily, requiring more reference symbols for more reliable channel estimation. To achieve dynamic allocation of reference signals for DFT-S-OFDM, special DFT-S-OFDM symbols can be used.

[0079] Figure 5An exemplary transmitter 510 and receiver 560 structure capable of transmitting and receiving the proposed special DFT-S-OFDM symbols is shown. The transmitter 510 (e.g., a UE) may have K DFT blocks, each of size M1518. KM2 reference symbols (or pilots) need to be transmitted in the frequency domain (i.e., at the input of IDFT operation 520). To achieve this, the M2 input of DFT block 523 can be set to zero to enable interference cancellation, and the M1 input 518 can be modulated data symbols, where M1 + M2 = M. The positions of the zero symbols and data symbols can be randomized and may differ from those shown in the figure. The position of the zero samples can be selected such that the receiver observes at least M3 + 1 samples. At the output of each DFT block, every M3 samples can be discarded and replaced with reference symbols 530, where M3 = M1 / M2. This can be done by perforating the interleaved outputs. For example, one or more outputs of DFT block 523 can be perforated, and each perforated output can be replaced with an RS symbol. Punched outputs can be selected to have an interleaved pattern (e.g., every nth output is selected (n = M3)).

[0080] After replacing these samples with RS symbols, the new vector is fed into the input of IDFT block 520. For example, when M=8 and M2=2 reference symbols {r1,r2| are needed for 8 subcarriers. Then, the input of the DFT block can be {d1,d2,…,d6,0,0} (in which case M1=6). When {x1,x2,…,x8} is the output of the DFT, after discarding every… After replacing the DFT outputs with {r1,r2}, we obtain {r1,x2,x3,x4,r2,x6,x7,x8}, which will be fed into the IDFT block to generate the time-domain signal. Note that reference symbols can also be inserted with offsets, for example, {x1,r1,x3,x4,x5,r2,x7,x8} when S=1. Finally, CP 535 is appended to the output of IDFT block 520.

[0081] At the receiver side 560, up to IDFT operation 564, signal processing is similar to that used for a receiver of DFT-S-OFDM signals. Subcarriers carrying the reference signal at the output of the DFT block can be used for channel estimation. Furthermore, if subcarriers discarded at the transmitter side are not replaced by the reference signal (i.e., replaced by zero), the corresponding subcarriers at the receiver DFT output 570 can be used for noise or interference power estimation.

[0082] Because some DFT block outputs are replaced by reference symbols or pilots on the transmitter side, the IDFT output on the receiver side is interfered with due to the "no" operation 575. However, the interference can be recovered from the M2 output 577 of the IDFT block and can be used to remove interference at another output 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 as follows: Figure 6 The zero offset is given (i.e., S = 0). The IC block 580 can also be improved using an iterative receiver architecture.

[0083] In another exemplary embodiment, if it is necessary to transmit some data symbols in the frequency domain, then Figure 5 The reference symbol r shown ij It can also be replaced by data symbols. Therefore, Figure 5 The system architecture shown allows for the simultaneous transmission of DFT-S-OFDM and OFDM signals.

[0084] In another embodiment, consider a single-user scenario consisting of a transmitter and a receiver communicating via a wireless channel. The data symbols to be transmitted within a single DFT-s-OFDM symbol can be vectors. The elements, where N d It refers to the number of data symbols. In basic DFT-s-OFDM, firstly, through the mapping matrix... Map data symbols to... The input is represented by the DFT matrix, where M is the DFT size and M = N. d As a special case, then through another mapping matrix. The output of the DFT is mapped to a set of subcarriers in the frequency domain. Without loss of generality, a mapping matrix M can be constructed. f This allows it to allocate M local or interleaved subcarriers to achieve low PAPR. Finally, matrix M... f The output is transmitted via F in the following manner H Convert to time domain:

[0085] x = F H M f DM t d, Equation (1)

[0086] in It is the inverse DFT (IDFT) matrix, and N is the number of subcarriers.

[0087] Suppose the channel impulse response (CIR) between the transmitter and receiver is a vector... in This refers to the number of taps. Assume the size of the loop prefix is ​​greater than... Then the received signal vector y can be expressed as:

[0088] y = Hx + n, Equation (2)

[0089] Where is a cyclic convolution matrix that models the interaction between the transmitted signal x and the channel h, and is additive white Gaussian noise (AWGN) with variance σ 2 .

[0090] At the receiver, by considering the effect of the multipath channel, the operations applied at the transmitter are reversed. The receiver operation can be expressed as:

[0091]

[0092] Where is the estimated data symbol vector, and is the equalizer that eliminates the effect of the multipath channel. The equalizer Q is a diagonal matrix and can be derived by using the minimum mean square error (MMSE) criterion.

[0093] As can be seen in Equation (1), the data symbols are distributed in frequency by the matrix D in DFT-s-OFDM. Therefore, traditional DFT-s-OFDM does not leave space for the frequency-domain RS in the M-dimensional subspace spanned by the M columns of F M . To allow the receiver to estimate the channel, the RS can be sent with another DFT-s-OFDM symbol by using a fixed sequence (e.g., the Zadoff-Chu sequence as in LTE). However, since the number of estimated coefficients required to infer the channel frequency response may be significantly less than M, using two separate DFT-s-OFDM symbols can significantly reduce the data rate.

[0094] To insert the RS at certain tones, different strategies can be followed, including the following. One option is to puncture the information in the frequency domain by relying on the redundancy introduced by the channel coding. However, since the number of unknowns (i.e., N d (=M)) is greater than the number of observations in one symbol after puncturing (i.e., M - N p ), i.e., N d =M>M - N p , where N p >0 is the number of punctured samples in the frequency, a recoverable DFT-s-OFDM signal may not be generated at the receiver.

[0095] In another option, the number of data symbols can be reduced to N d <M, and the size M of D can be changed to Nd This is to accommodate reference symbols within an M-dimensional subspace. However, all symbols within a frame or subframe typically do not require reference symbols. Therefore, this option necessitates the use of DFT blocks with variable sizes by both the transmitter and receiver, which may not be suitable for radix-2 FFT implementations.

[0096] In the third option, reduce the number of data symbols N. d ≤M, while keeping the size of the DFT at M, such that the number of unknowns is less than or equal to the number of observations after perforation, i.e., N. d ≤MN p This option does not increase the complexity of the transmitter. However, puncturing implicitly interferes with the data symbols, and recovering the data symbols with a low-complexity receiver is not straightforward. The following description overcomes this challenge and shows that data symbols can be recovered with a low-complexity receiver by employing certain puncturing patterns and inserting zeros at certain positions before the transmitter's DFT spreading block.

[0097] Figure 7 An example of a transmitter 710 and receiver 760 for generalized DFT-S-OFDM with frequency domain reference symbols is shown. In this scheme, N is introduced before the DFT extension 720. z =MN d ≥N p The empty symbol 715 makes the number of observations greater than or equal to the number of holes N in the frequency. p The number of unknowns after a sample. Considering that at the output of a DFT 720 with offset, P punches a symbol every N1 symbols, it can be represented by a matrix. This represents the perforation operation 730. Due to its periodic structure, matrix P can be represented as:

[0098]

[0099] in And N i +1 is an integer multiple of M. Without loss of generality, the perforation vector passes through an empty matrix. By inserting N p To map zeros to another vector in M-dimensional space, to fit the vector c z The frequency domain reference symbol is represented, where l = 1, 2, ..., N. p (940). Reference symbols can be uniformly distributed at frequency (950) using IDFT blocks to improve channel estimation performance at receiver (950). In this case, matrix N can be chosen:

[0100]

[0101] The entire sending operation can ultimately be represented as:

[0102]

[0103] in It is a scaling factor that scales the energy x to N after perforation. d CP(955) can be appended before the transmission symbol.

[0104] As mentioned above, the punching operation implicitly distorts the output of the DFT extension and significantly interferes with the data symbols. The interference with data and null symbols can be expressed as:

[0105] r = D H P H PDd e -d e Equation (7)

[0106] in It is a mapped data symbol, and can be used as Acquired, and It is the interference vector. The interference vector is not arbitrary because every N in the DFT expansion block... j The outputs are all empty. The structure of the interference vector r can be obtained by using the following lemma.

[0107] The following Lemma 1 yields two important results. First, by using Lemma 1, it can be deduced that the k-th element of vector r is... and Secondly, due to This indicates that the degrees of freedom of the interference vector r are N. p Therefore, it can be observed only with one period p. k The N corresponding to r in the samples within p Each element, and through the use of relations The remainder of the derivative r is derived to regenerate the vector r. In other words, M t It should be chosen such that the position of the empty sign captures at least one period of p. k The sample. Therefore, Lemma 1 inspires where to insert empty symbols to allow the receiver to recover the data symbols without any distortion. For example, let M = 8, S = 0, and N p =2, and assume that the input to the selected DFT block is (d1,d2,…,d2,0,0) (i.e., N z =2,M t =I7). Let (x1,x2,…,x8) be the output of the DFT. In every N... IAfter discarding the four DFT outputs and replacing them with (c1, c2), we obtain {c1, x2, x3, x4, c2, x6, x7, x8}, which will be fed into IDFT block 750 to generate the time-domain signal. At the receiver side, only six samples related to the data symbols are output from the IDFT block. By ignoring the effect of noise on sharpness and using Lemma 1, we can see that the equalization vector d... e The IDFT is (d1+p1,d2+p2,d3+p1,…,d5+p1,d6+p2,p1,p2), since p k =p k+2 The last two samples reveal the interference vector r. On the other hand, the choice of the data vector (0,d1,0,d2,…,d6) does not allow the receiver to regenerate r as the first and third samples carrying the same interference sample after the punching.

[0108] At receiver side 760, until the frequency domain demapping operation, i.e. 763. For both conventional DFT-s-OFDM and the proposed scheme, the signal processing is the same. In contrast to conventional DFT-s-OFDM, the subcarrier carrying the reference signal at the DFT output can be used for channel estimation (CHEST) 765 in the proposed scheme. Using the estimated channel, the data-bearing subcarrier first passes through… The equalizer is 770, and the sign of the equalizer's output is then passed through P. H 775 is mapped to the input of the IDFT. IDFT D H The output of the 780 can be represented as:

[0109]

[0110] in This refers to the received vector, including the effects of noise, equalization, and punching. Considering the structure of interference caused by punching, a simple method to recover the data symbols is:

[0111]

[0112] in and It is M t The submatrix, and M t =[M t.d M t,r ],and It is a reconstruction matrix, based on the relation specified in Lemma 1. and Calculate the distortion caused by perforation. As a special case, when S=0 and M... t =I MWhen R becomes a repeating matrix given by the following equation:

[0113]

[0114] This significantly simplifies the receiver structure. For example, if d e If (d1+p1,d2+p2,d3+p1,…,d5+p1,d6+p2,p1,p2), then R copies the last two samples N. I =3 times, and can be obtained from The data symbols are recovered by subtracting the copy vector from the remaining samples (as shown in equation (9)).

[0115] While the method discussed above enables a low-complexity receiver, it amplifies the noise by 3 dB due to the addition of two noisy observations via equation (9). An effective way to mitigate this noise amplification is to use an iterative receiver designed to eliminate the noise in the second part of equation (9), i.e., the distortion caused by perforation. For this purpose, the data symbol estimate for the i-th iteration is as follows:

[0116]

[0117] in Then, the estimated data symbols Mapped to the nearest sign in the constellation by a nonlinear function f(·) (i.e., demodulation), and Prepared for the next iteration as follows:

[0118]

[0119] Because of After the decision was made Therefore, it effectively removes noise from the second part of equation (11) and leads to a better estimate for the (i+1)th iteration.

[0120] It is important to emphasize that the proposed scheme described in this paper introduces a punch-hole mode and the number of reference signals N. p The number of empty symbols N z And some conditions for the pattern of empty symbols. First, the receiver structure discussed above utilizes the DFT with offset S every N. i Output the fact that it was punched. Second, N z ≥N p It must be maintained, and N at the input of the DFT expansion block z The pattern of empty symbols should capture at least one distortion cycle due to perforation to produce recoverable DFT-s-OFDM symbols. A simple approach is to consider Nz A pair of adjacent empty symbols.

[0121] There is still room for improvement in receiver performance. For example, a simple way to improve receiver performance is to increase the number of zero symbols, which is greater than the number of punched symbols, i.e., N. z >N p In this scenario, the receiver can combine samples to compute a more reliable interference vector at the cost of lower spectral efficiency. The receiver architecture described above can also be improved by including a channel codec and demodulation on the feedback branch.

[0122] Without loss of generality, the scheme described herein can be used for multiple DFT blocks. Furthermore, if the subcarriers dropped at the transmitter side are not replaced by RS (i.e., replaced by zero), the corresponding subcarriers at the receiver DFT output can also be used for noise or interference power estimation.

[0123] As described above, Lemma 1 will now be described. Lemma 1 (Periodic Disturbance): For n = 0, 1, ..., M-1, let (X... n (size) The sequence, let (Y) n This is achieved by utilizing the offset S, where S≤N i , (X) n ) every N i , Another sequence is obtained by setting each element to zero. Then, Y can be... n The IDFT decomposition is as follows:

[0124] For n = 0, ..., M-1, y k =x k +r k Equation (13)

[0125] Where (y) k ) is (Y n IDFT of (x) k ) is (X n The IDFT of ) and for k = 0, ..., M-1, (r k ) is by Given a sequence of size M, where (p k ) is a periodic A periodic sequence.

[0126] Sequence (Y) n Elements of ) can use auxiliary sequences (R) n )express:

[0127] Y n =X n +Rn Equation (14)

[0128] in:

[0129]

[0130] Since the IDFT operation is linear, (Y n The IDFT of y can be represented as (y k )=(x k )+(r k ), where (r k ) is (R n IDFT of ) (r k The elements of ) can be calculated in the following way:

[0131]

[0132]

[0133] Where (s) m )yes IDFT, and In equation 16, (a) is true because when When r is not an integer n It is zero, and (b) due to the exponential function The periodicity of this is true, which leads to

[0134] In some cases, when using a single-carrier waveform such as DFT-s-OFDM, all subcarriers within the allocated bandwidth can be used to transmit reference signal (pilot) symbols. In this transmission mode, the number of waveform symbols carrying the reference signal (e.g., DFT-s-OFDM symbols) may be dynamically changed. As an example, in LTE uplink data transmission, a subframe consists of 14 DFT-s-OFDM symbols, two of which are used to transmit pilots. If the WTRU requires better channel estimation, for example due to mobility, the number of symbols used for RS transmission may be increased from two to three or more.

[0135] Changing the number of pilot symbols will alter the amount of resources allocated to data transmission. Consequently, it may be necessary to modify the transport block size and / or coding rate. 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 for each transmission in the control channel. For each possible number of pilot symbols, a corresponding value for the transport block size can be defined.

[0136] Figure 8An example subframe is shown, in which some symbols are generated within a specific time interval using a different set of waveform parameters than the remaining symbols. Figure 8 In this process, the time interval used for the first PUSCH symbol 810 is used to transmit two DFT-s-OFDM symbols, each of which 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.

[0137] When the waveform is not a single-carrier waveform, for example, when it is OFDM, certain subcarriers of some OFDM symbols may be dynamically or semi-statically configured 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. Multiple OFDM symbols may be transmitted within a specific time interval, where some OFDM symbols can be generated by using different waveforms and parameter sets than the remaining OFDM symbols.

[0138] exist Figure 9 An example is provided where, in addition to the subcarriers initially configured to transmit the reference symbol, some subcarriers in the last OFDM symbol of the subframe are configured to transmit the reference symbol. Furthermore, the first two OFDM symbols have half the duration of the remaining OFDM symbols, and some subcarriers of the first OFDM symbol are also configured for reference symbol transmission. It should be noted that, due to different waveform parameter sets, the first two OFDM symbols may have a larger subcarrier spacing than the remaining OFDM symbols. Additionally, although the cyclic prefix (CP) is not shown in the figure, the CP may precede each OFDM symbol. These techniques can be applied to other multicarrier waveforms such as windowed OFDM, filtered OFDM, and filterbank multicarrier.

[0139] While the features and elements of the invention have been described above in specific combinations, it will be understood by those skilled in the art that each feature or element can be used alone without other features and elements, or in various combinations with any other features and elements of the invention. Furthermore, the methods described in this invention can be implemented in a computer program, software, or firmware executed by a computer or processor, wherein the computer program, software, or firmware is contained in a computer-readable storage medium. Examples of computer-readable media include electronic signals (transmitted via 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, buffer memory, semiconductor storage devices, magnetic media (e.g., internal hard disks or removable disks), magneto-optical media, and optical media such as CD-ROMs and digital versatile optical discs (DVDs). The processor associated with the software can be used to implement a radio frequency transceiver used in a WTRU, UE, terminal, base station, RNC, or any host.

Claims

1. A method performed by a wireless transmit / receive unit (WTRU), comprising: The WTRU receives first dynamic scheduling information from the base station, wherein the first dynamic scheduling information allocates a first discrete Fourier transform extended orthogonal frequency division multiplexing (DFTS-OFDM) symbol for a first reference signal symbol for transmission of a first physical uplink shared channel (PUSCH); The WTRU uses a DFTS-OFDM with the first reference signal at the first DFTS-OFDM symbol assigned to the first reference signal symbol to transmit the first PUSCH transmission; The WTRU receives second dynamic scheduling information, wherein the second dynamic scheduling information allocates a second DFTS-OFDM symbol for the transmission of a second reference signal symbol for the second physical uplink shared channel (PUSCH); as well as The WTRU uses a DFTS-OFDM symbol with the second reference signal at the second DFTS-OFDM symbol allocated for the second reference signal symbol to transmit the second PUSCH transmission, wherein the first DFTS-OFDM symbol for the first reference signal symbol is different from the second DFTS-OFDM symbol for the second reference signal symbol, and wherein the symbol time between the first dynamic scheduling information and the second dynamic scheduling information is different.

2. The method of claim 1, wherein the base station is a g node B and the WTRU is a new radio (NR) user equipment (UE).

3. The method of claim 1, wherein in response to receiving second dynamic scheduling information from the WTRU, the second PUSCH transmission includes empty subcarriers in the symbols used for transmitting reference signals.

4. A wireless transmit / receive unit (WTRU), the WTRU comprising: The receiver is configured to receive first dynamic scheduling information from the base station, wherein the first dynamic scheduling information allocates first discrete Fourier transform extended orthogonal frequency division multiplexing (DFTS-OFDM) symbols for transmission of first reference signal symbols in the first physical uplink shared channel (PUSCH). The transmitter is configured to transmit the first PUSCH using DFTS-OFDM with the first reference signal at the first DFTS-OFDM symbol assigned for the first reference signal symbol; The receiver is configured to receive second dynamic scheduling information, wherein the second dynamic scheduling information allocates second DFTS-OFDM symbols for second reference signal symbols for transmission of the second physical uplink shared channel (PUSCH); as well as The transmitter is configured to transmit the second PUSCH transmission using a DFTS-OFDM symbol having the second reference signal at the second DFTS-OFDM symbol assigned for the second reference signal symbol, wherein the first DFTS-OFDM symbol for the first reference signal symbol is different from the second DFTS-OFDM symbol for the second reference signal symbol, and wherein the symbol time between the first dynamic scheduling information and the second dynamic scheduling information is different.

5. The WTRU of claim 4, wherein the base station is a g node B and the WTRU is a New Radio (NR) User Equipment (UE).

6. The WTRU according to claim 4, wherein: In response to receiving second dynamic scheduling information, the transmitter is further configured to transmit a second signal on a PUSCH, the PUSCH including empty subcarriers in symbols used for transmitting reference signals.

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