Method for supporting BSS edge user transmission

Abstract

Methods for supporting BSS edge user transmissions are described herein, and in particular methods and apparatus for enhancing random access procedures are described. A method performed by an access point (AP) may include allocating a plurality of random access (RA) resource units (RA-RUs) for transmitting messages from a station (STA) to the AP on a higher frequency band or a lower frequency band. The method may include transmitting one or more physical layer convergence process (PLCP) protocol data units (PPDUs) to a station (STA) over the higher or lower frequency band. Each of the one or more PPDUs may include a trigger frame, and the trigger frame may include an indication of the plurality of RA-RUs and a target received signal strength indicator (TRSSI) associated with at least one of the higher frequency band or the lower frequency band. The method may include receiving the message from the STA in one of a plurality of RA-RUs in response to the trigger frame.

Description

This application is a divisional application of Chinese patent application No. 202080035197.6, filed on May 8, 2020, entitled “Method for Supporting BSS Edge User Transmission”, the contents of which are incorporated herein by reference. CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 846,183, filed May 10, 2019, the contents of which are incorporated herein by reference. Background Art

[0002] In the field of wireless communications, various systems, methods, and devices can be used to enhance and improve wireless communications. For example, protocols such as IEEE 802.11 can provide wireless local area network (WLAN) operations involving two or more devices. These protocols are used worldwide and have many use cases. As new technologies develop, new protocols may be needed to address the new use cases enabled by these technologies.

[0003] A WLAN operating in infrastructure basic service set (BSS) mode may include an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may access or interface with a distribution system (DS) or another type of wired or wireless network that carries traffic to and from the BSS. Traffic originating from outside the BSS and destined for a STA may arrive through the AP and be delivered to the STA. Traffic originating from the STA and bound for a destination outside the BSS may be sent to the AP for delivery to its respective destination. Traffic between STAs within the BSS may also be sent through the AP; for example, a source STA may send traffic to the AP, and the AP may deliver the traffic to the destination STA. This type of traffic between STAs within a BSS may be referred to as peer-to-peer traffic. Such peer-to-peer traffic may also be sent directly between a source STA and a destination STA over the DLS using 802.11e Direct Link Setup (DLS) or 802.11z Channelized Transport DLS (TDLS). A WLAN using independent BSS (IBSS) mode may not have an AP and / or STAs that communicate directly with each other. This communication mode may be referred to as an "ad hoc" communication mode. Summary of the Invention

[0004] Methods and apparatus for enhancing a random access procedure are described herein. A method performed by an access point (AP) may include allocating a plurality of random access (RA) resource units (RA-RUs) for transmitting a message from a station (STA) to the AP on an upper frequency band or a lower frequency band. The method may include transmitting one or more physical layer convergence procedure (PLCP) protocol data units (PPDUs) to the station (STA) on the upper or lower frequency band. Each of the one or more PPDUs may include a trigger frame, and the trigger frame may include an indication of the plurality of RA-RUs and a target received signal strength indicator (TRSSI) associated with at least one of the upper frequency band or the lower frequency band. The method may include receiving the message from the STA in one of the plurality of RA-RUs in response to the trigger frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The present invention may be understood in more detail from the following description given by way of example with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0006] Figure 1A is a system diagram illustrating an exemplary communication system in which one or more disclosed embodiments may be implemented;

[0007] Figure 1B is a diagram showing that according to an embodiment, Figure 1A A system diagram illustrating an exemplary wireless transmit / receive unit (WTRU) for use within a communication system is shown;

[0008] Figure 1C is a diagram showing that according to an embodiment, Figure 1A A system diagram illustrating an exemplary radio access network (RAN) and an exemplary core network (CN) used within the communication system;

[0009] Figure 1D is a diagram showing that according to an embodiment, Figure 1A A system diagram of another exemplary RAN and another exemplary CN used within the communication system shown;

[0010] Figure 2 is an example representation of a qualified RU in the lower frequency band for each of the two STA categories;

[0011] Figure 3 is an example representation of a qualified RU in the higher frequency band for each of the two STA categories;

[0012] Figure 4AAnother diagram of an embodiment of a multi-band trigger frame including five STAs and a multi-band AP 401 is described;

[0013] Figure 4B It is a description of the low-band RA-RU eligibility of multiple STAs relative to the high-band TRSSI;

[0014] Figure 5 An example method is shown in which an AP can optimize the allocation and selection of RA-RUs within multiple frequency bands; and

[0015] Figure 6 are corresponding examples of methods that may be performed by a STA to use and select an allocated RA-RU. DETAILED DESCRIPTION

[0016] Figure 1A 1 is a schematic diagram illustrating 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 that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content by sharing system resources, including wireless bandwidth. For example, the communication system 100 may utilize 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-tailing unique word discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, and filter bank multi-carrier (FBMC), among others.

[0017] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112. However, it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network components. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, any of the WTRUs 102a, 102b, 102c, 102d may be referred to as a station (STA), which may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical equipment and applications (e.g., remote surgery), industrial equipment and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated process chain environments), consumer electronic devices, and devices operating on commercial and / or industrial wireless networks, etc. Any of the WTRUs 102a, 102b, 102c, 102d may be interchangeably referred to as a UE.

[0018] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to facilitate access to one or more communication networks (e.g., the CN 106, the Internet 110, and / or other networks 112) by wirelessly interfacing with at least one of the WTRUs 102a, 102b, 102c, 102d. For example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B (eNB), a Home Node B, a Home eNode B, a next generation Node B such as a gNode B (gNB), a New Radio (NR) Node B, a site controller, an access point (AP), a wireless router, and the like. While each of the base stations 114a, 114b is depicted as a single component, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network components.

[0019] Base station 114a may be part of the RAN 104, which may also include other base stations and / or network components (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, and the like. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, referred to as cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of both. A cell may provide wireless service coverage for a specific geographic area that may be relatively fixed or may vary over time. A cell may be further 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, one for each sector of the cell. In an embodiment, base station 114a may employ multiple-input, multiple-output (MIMO) technology and may use multiple transceivers for each sector of the cell. For example, by employing beamforming, signals may be transmitted and / or received in a desired spatial direction.

[0020] 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, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0021] More specifically, as described above, the communication system 100 may be a multiple access system and may utilize one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, and 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may utilize Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​Uplink (UL) Packet Access (HSUPA).

[0022] 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).

[0023] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology that may use NR to establish the air interface 116, such as NR radio access.

[0024] 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 jointly implement LTE radio access and NR radio access (e.g., using dual connectivity (DC) principles). Thus, the air interface used by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0025] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), and GSM EDGE (GERAN), among others.

[0026] Figure 1AThe base station 114b in the may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any appropriate RAT to facilitate wireless connectivity in a local area, such as a business location, a residence, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may establish a wireless local area network (WLAN) by implementing a radio technology such as IEEE 802.11. In an embodiment, the base station 114b and the WTRUs 102c, 102d may establish a wireless personal area network (WPAN) by implementing a radio technology such as IEEE 802.15. In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may establish a picocell or a femtocell by utilizing a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, and the like). As Figure 1A As shown, base station 114b may be directly connected to Internet 110. Thus, base station 114b does not need to access Internet 110 via CN 106.

[0027] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or may perform advanced security functions such as user authentication. Although in Figure 1A Although not shown, it will be appreciated that the RAN 104 and / or CN 106 may be in direct or indirect communication with other RANs that employ the same RAT or a different RAT as the RAN 104. For example, in addition to being connected to the RAN 104, which may employ NR radio technology, the CN 106 may also be in communication with other RANs (not shown) that may employ GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0028] 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 that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer network devices that uses common communication protocols, such as TCP, User Datagram Protocol (UDP), and / or IP from the Transmission Control Protocol / Internet Protocol (TCP / IP) suite of internet protocols. The networks 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may use the same RAT as the RAN 104 or a different RAT.

[0029] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). Figure 1A The WTRU 102c shown may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0030] Figure 1B is a system diagram illustrating an exemplary WTRU 102. Figure 1B As shown, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and / or peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing components while remaining consistent with an embodiment.

[0031] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, 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. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, however, it should be understood that the processor 118 and the transceiver 120 may also be integrated together in an electronic package or chip.

[0032] The transmit / receive element 122 may be configured to transmit or receive signals to or 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. As another example, in another embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive RF and light signals. It should be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0033] Although Figure 1B 102 as a single component, the WTRU 102 may include any number of transmit / receive components 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive components 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0034] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As described above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers that allow the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0035] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit) and may receive user input data from these components. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Furthermore, the processor 118 may access information from, and store data in, any 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, for example, on a server or a home computer (not shown).

[0036] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (Ni-Cd), nickel-zinc (Ni-Zn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0037] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) via the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information using any suitable positioning method while remaining consistent with the embodiments.

[0038] The processor 118 may also be coupled to other peripheral devices 138, wherein the peripheral devices may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripheral devices 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, Modules, frequency modulation (FM) radio units, digital music players, media players, video game console modules, Internet browsers, virtual reality and / or augmented reality (VR / AR) devices, and activity trackers, etc. The peripheral devices 138 may include one or more sensors. The sensors may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and a humidity sensor, etc.

[0039] The WTRU 102 may include a full-duplex radio in which the reception or transmission of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. A full-duplex radio may include an interference management unit that reduces and / or substantially eliminates self-interference via signal processing in hardware (e.g., chokes) or by a processor (e.g., a separate processor (not shown) or by the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio that transmits and receives some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or DL ​​(e.g., for reception)).

[0040] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c using an E-UTRA radio technology over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0041] The RAN 104 may include eNode-Bs 160a, 160b, 160c, however, it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0042] Each of the eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in the UL and / or DL, and the like. Figure 1C As shown, the eNode-Bs 160a, 160b, and 160c may communicate with each other via an X2 interface.

[0043] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although the foregoing components are depicted as being part of the CN 106, it should be understood that any of these components may be owned and / or operated by an entity other than the CN operator.

[0044] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, performing bearer activation / deactivation processing, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may also provide control plane functions for switching between the RAN 104 and other RANs (not shown) employing other radio technologies, such as GSM and / or WCDMA.

[0045] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may also perform other functions, such as anchoring the user plane during inter-eNB handovers, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0046] The SGW 164 may be connected to the PGW 146, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0047] 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, such as an IP Multimedia Subsystem (IMS) server, which may serve as an interface between the CN 106 and the PSTN 108. The CN 106 may also 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.

[0048] Although Figures 1A-1D While the WTRU is described as a wireless terminal, it is appreciated that in certain representative embodiments, such a terminal may utilize a (eg, temporary or permanent) wired communication interface with a communication network.

[0049] In a representative embodiment, the other network 112 may be a WLAN.

[0050] A WLAN employing an infrastructure basic service set (BSS) model may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may access or interface with a distributed system (DS) or other type of wired / wireless network that routes traffic into and / or out of the BSS. Traffic originating from outside the BSS and destined for a STA may be routed through the AP and delivered to the STA. Traffic originating from a STA and destined for a destination outside the BSS may be sent to the AP for delivery to the destination. Traffic between STAs within the BSS may be routed through the AP, for example, where a source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. This point-to-point traffic may be routed between (e.g., directly between) the source and destination STAs using a direct link setup (DLS). In certain representative embodiments, the DLS may utilize 802.11e DLS or 802.11z channelized DLS (TDLS). For example, a WLAN using an independent BSS (IBSS) mode does not have an AP, and STAs (e.g., all STAs) within or using the IBSS can communicate directly with each other. The IBSS communication mode may sometimes be referred to as an "ad-hoc" communication mode.

[0051] When using 802.11ac infrastructure mode or a similar mode of operation, the AP may transmit beacons on a fixed channel (e.g., a primary channel). The primary channel may have a fixed width (e.g., a 20 MHz bandwidth) or a dynamically set width. The primary channel may be the operating channel of the BSS and may be used by STAs to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access with collision avoidance (CSMA / CA) (e.g., in an 802.11 system) may be implemented. For CSMA / CA, STAs (e.g., each STA), including the AP, may sense the primary channel. If a particular STA senses / detects and / or determines that the primary channel is busy, the particular STA may back off. In a given BSS, at any given time, one STA (e.g., only one station) may transmit.

[0052] High throughput (HT) STAs may communicate using a 40 MHz wide channel (eg, by combining a 20 MHz wide primary channel with adjacent or non-adjacent 20 MHz wide channels to form a 40 MHz wide channel).

[0053] Very High Throughput (VHT) STAs can support channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. 40 MHz and / or 80 MHz channels can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining eight contiguous 20 MHz channels or by combining two discontinuous 80 MHz channels (this combination may be referred to as an 80+80 configuration). For the 80+80 configuration, after channel coding, the data can be passed and 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 onto 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 can be reversed, and the combined data can be sent to the medium access control (MAC).

[0054] 802.11af and 802.11ah support operating modes below 1 GHz. Compared to 802.11n and 802.11ac, the channel operating bandwidth and carrier used in 802.11af and 802.11ah are reduced. 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 a representative embodiment, 802.11ah can support meter type control / machine type communication (MTC) (e.g., MTC devices in macro coverage areas). MTC devices can have certain capabilities, such as limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. MTC devices can include a battery, and the battery life of the battery is above a threshold (e.g., for maintaining a very long battery life).

[0055] For WLAN systems that support multiple channels and channel bandwidths (e.g., 802.11n, 802.11ac, 802.11af, and 802.11ah), these systems include a channel that can be designated as a primary channel. The bandwidth of the primary channel can be 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 a STA, where the STA is derived from all STAs operating in the BSS that supports the minimum bandwidth operating mode. In the example of 802.11ah, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes, for STAs that support (e.g., only) 1MHz mode (e.g., MTC-type devices), the primary channel width can be 1MHz. Carrier sensing and / or network allocation vector (NAV) settings can depend on the status of the primary channel. If the primary channel is busy (e.g., because a STA (which only supports 1MHz operation) is transmitting to the AP), then all available frequency bands can be considered busy, even if most of the available frequency bands remain idle.

[0056] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. Depending on the country code, the total bandwidth available for 802.11ah ranges from 6MHz to 26MHz.

[0057] Figure 1D 1 is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c using NR radio technology over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0058] The RAN 104 may include gNBs 180a, 180b, and 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. Each of the gNBs 180a, 180b, and 180c may include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNBs 180a and 180b may use beamforming to transmit and / or receive signals to and / or from the gNBs 180a, 180b, and 180c. Thus, for example, the gNB 180a may use multiple antennas to transmit wireless signals to and receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, and 180c may implement carrier aggregation. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be in unlicensed spectrum, while the remaining component carriers may be in licensed spectrum. In an embodiment, gNBs 180a, 180b, and 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0059] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with a scalable digital configuration. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may be different for different transmissions, different cells, and / or different portions of the radio transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of different or scalable lengths (e.g., containing different numbers of OFDM symbols and / or lasting different absolute time lengths).

[0060] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing other RANs (e.g., the eNode-Bs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed frequency band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNBs 180a, 180b, 180c while communicating / connecting with another RAN (e.g., the eNode-Bs 160a, 160b, 160c). For example, the WTRUs 102a, 102b, 102c may communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously by implementing the DC principle. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may serve as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput to serve the WTRUs 102a, 102b, 102c.

[0061] Each gNB 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support network slicing, DC, implement interworking between NR and E-UTRA, route user plane data to user plane functions (UPFs) 184a, 184b, and route control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. Figure 1D As shown, gNB180a, 180b, and 180c can communicate with each other through the Xn interface.

[0062] Figure 1DThe illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and may include data networks (DNs) 185a, 185b. Although the aforementioned components are described as part of the CN 106, it should be understood that any of these components may be owned and / or operated by an entity other than the CN operator.

[0063] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, managing registration areas, terminating non-access stratum (NAS) signaling, and mobility management, among other things. The AMF 182a, 182b may use network slicing processing to customize the CN support provided to the WTRUs 102a, 102b, 102c based on the type of service used by the WTRUs 102a, 102b, 102c. As an example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, and services for MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that use other radio technologies (e.g., LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi).

[0064] The SMF 183a, 183b may connect to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also connect to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and may configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating WTRU or UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing DL data notifications, among others. The PDU session type may be IP-based, non-IP-based, Ethernet-based, and so on.

[0065] The UPF 184a, 184b can be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which can 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 184, 184b can perform other functions such as routing and forwarding packets, implementing user plane policies, supporting multi-host PDU sessions, handling user plane QoS, buffering DL packets, and providing mobility anchoring processing, etc.

[0066] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. Furthermore, 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. In one embodiment, the WTRUs 102a, 102b, 102c may connect to the DN 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the local DN 185a, 185b.

[0067] In view of Figures 1A-1D and about Figures 1A-1D

[0015] As described herein, one or more or all of the functionality described herein with respect to one or more of the following may be performed by one or more emulated devices (not shown): WTRUs 102a-d, base stations 114a-b, eNodeBs 160a-c, MMEs 162, SGWs 164, PGWs 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or one or more other devices described herein. These emulated devices may be one or more devices configured to emulate one or more or all of the functionality described herein. For example, these emulated devices may be used to test other devices and / or emulate network and / or WTRU functionality.

[0068] The simulation device can be designed to perform one or more tests on other devices in a laboratory environment and / or an operator network environment. For example, the one or more simulation devices can perform one or more or all functions while being implemented and / or deployed in whole or in part as part of a wired and / or wireless communication network to test other devices within the communication network. The one or more simulation devices can perform one or more or all functions while being temporarily implemented or deployed as part of a wired and / or wireless communication network. The simulation device can be directly coupled to other devices to perform the test, and / or can use over-the-air wireless communication to perform the test.

[0069] One or more emulation devices can perform one or more functions, including all functions, while not being implemented or deployed as part of a wired and / or wireless communication network. For example, the emulation device can be used in a test lab and / or a test scenario of a wired and / or wireless communication network that has not been deployed (e.g., tested) to perform tests on one or more components. The one or more emulation devices can be test devices. The emulation device can transmit and / or receive data using direct RF coupling and / or wireless communication with the aid of RF circuitry (e.g., which can include one or more antennas).

[0070] IEEE802.11 TM The Extremely High Throughput WLAN (EHT) Study Group (SG) has been created to explore the scope and purpose of possible future modifications to provide enhanced throughput, enhanced reliability, reduced latency and jitter, and improved power efficiency in many usage scenarios. The IEEE Standards Board has approved the IEEE 802.11be Task Group (TG) based on the Project Authorization Request (PAR) and the Standards Development Standard (CSD) developed in the EHT SG. Examples of applications for such improvements in latency, throughput, and spectral efficiency to be supported in 802.11be include 4K / 8K video, gaming, virtual and augmented reality, remote offices, and cloud computing. In the 802.11be PAR, latency requirements may be imposed as new high-throughput, low-latency applications such as those mentioned above may proliferate.

[0071] This document describes mechanisms for low-latency transmission in 5G New Radio (NR) and WLAN. 5G NR networks can be designed to support three or more service categories, including enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). The mechanisms and procedures designed for URLLC can provide advanced services for latency-sensitive devices or services. Configuration grant transmission can be adopted in 5G NR to reduce the number of service request or response frames exchanged between the fifth-generation Node B (gNB) and the UE, allowing UEs with low-latency services to communicate on pre-configured resources without having to request transmission.

[0072] In a WLAN, STAs can use various protocols to transmit information on channels occupied by other STAs. For example, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) channel access can be used for multiple access. When a STA monitors the shared medium for a certain period of time and determines that the medium is idle, it can perform transmissions without authorization from its associated AP. The channel sensing resolution can be, for example, 20 MHz or higher.

[0073] For example, in 802.11ax, Orthogonal Frequency Division Multiple Access (OFDMA) can be used for both downlink (DL) and uplink (UL) transmissions. Various mechanisms and procedures are defined to enable one or more STAs to transmit simultaneously in different frequency units. In some cases, concurrent UL OFDMA transmissions can be triggered and scheduled by an associated AP. At least two schemes can be supported for low-latency transmissions, including UL OFDMA-based random access (UORA) for associated and non-associated STAs and a null data packet (NDP) feedback reporting procedure.

[0074] For example, in 802.11ax, STAs can use the traditional CSMA / CA process to perform autonomous uplink transmission by sensing the entire channel, or use the UORA process to perform autonomous uplink transmission. The AP can use a trigger frame with a set of resource units on which associated STAs and / or unassociated STAs can send uplink traffic. The AP can assign the uplink modulation and coding set (MCS), length, and other related physical layer (PHY) parameters. The STA can use the UORA process to determine resources and send a triggered physical layer convergence procedure (PLCP) protocol data unit (PPDU). The AP can send an acknowledgment to the STA, such as a multi-STA block acknowledgment (BA).

[0075] Table 1 describes the format of the trigger frame. As shown, the trigger frame may include multiple fields. Each field may have a length that can be expressed, for example, in bits, bytes, octets, or symbols. These fields may include, for example, the STA's receiver address (RA), the STA's transmit address (TA), and a frame check sequence (FCS). Table 1: Trigger frames in 802.11ax

[0076] Table 2 describes the common information fields of the trigger frame. Table 2: Common information fields in trigger frames

[0077] As shown in Table 3, the user information field may provide details about each device except for NDP Feedback Report Poll (NFRP) triggering. Table 3: User information fields in trigger frames

[0078] For example, 802.11ax supports the transmission of Null Data Packet (NDP) Feedback Reports (NFRs). In some embodiments, the AP may send a trigger frame, and the trigger frame type, for example, given in the public information, may be an NDP Feedback Report Poll (NFRP). The AP may indicate that the feedback type is a resource request. A Start Association ID (AID) field may be included in the trigger frame. In some embodiments, a High Efficiency (HE) MU PPDU may not be used to carry the NFRP trigger.

[0079] The STA may detect the NFRP trigger and receive parameters and scheduling information for sending an NFR. The STA may obtain the NDP feedback report parameters, for example, from a management frame. The STA may follow the instructions provided by the NFRP trigger and the NDP feedback report parameters to send an NFR. In some embodiments, no acknowledgment is sent from the AP to the one or more STAs.

[0080] For example, the trigger frame of NFRP may have the same frame format as shown in Table 1. The common information field may be the same as shown in Table 2, however, in some cases, the user information field may be defined separately as shown in Table 4. Table 4: User Information Field in Trigger Frame for NFRP Triggering

[0081] The STA triggered by the AP may respond with a triggered PPDU. Table 5 shows an example of the triggered PPDU format. Transmissions triggered by the UORA may be transmitted using a single data stream. Table 5: Trigger-based PPDUs defined in 802.11ax

[0082] This raises challenges related to BSS coverage and edge user support. In uplink OFDMA-based access, one or more STAs may need to adjust their transmit power to approximately align the received power at the AP. For example, in 802.11ax, the AP can include its transmit power in the common information field of the trigger frame and / or include the UL target RSSI in the user information field of the trigger frame.

[0083] In an OFDMA-based random access procedure, one or more STAs can be triggered by a single trigger frame and can use the same user information field to perform their respective uplink transmissions. Consequently, multiple STAs can use a single UL target RSSI to adjust their transmit power. For users operating at the edge of BSS coverage, it is possible that even if one or more STAs use the maximum allowed transmit power, they may not be able to achieve the target RSSI. In some cases, this can lead to an imbalance in received power on the AP side.

[0084] During the OFDMA-based random access procedure, a non-AP HE STA can maintain an internal OFDMA contention window (OCW) and an internal OFDMA backoff (OBO) counter. The OCW can be an integer in the range from the minimum OCW size (OCWmin) to the maximum OCW size (OCWmax). A non-AP HE STA can obtain OCWmin and OCWmax from the most recently received UORA parameter set element carried in a beacon, probe response, association response frame, or reassociation response frame sent by the associated AP.

[0085] During OFDMA-based random access, some scenarios may involve a non-AP STA that has a pending frame for the AP and receives a trigger frame containing at least one eligible RA-RU. In this case, if the STA's OBO counter is not greater than the number of eligible RA-RUs in the trigger frame from the AP, the HE STA may set its OBO counter to zero and randomly select one of the eligible RA-RUs to consider for transmission. Otherwise, the STA may decrement its OBO counter by the number of eligible RA-RUs in the trigger frame.

[0086] The solutions discussed throughout this document can provide extensions for coverage extension and enhanced support for edge users. As described herein, the following embodiments can address the aforementioned challenges, among others. In some solutions, newly designed trigger frames and processes can be used to trigger STAs, STA groups, or subsets of STA groups that meet specific criteria to use random access resource units (RA-RUs) allocated in the trigger frame. The criteria can include, for example, one or more channel conditions, signal-to-noise ratio (SNR), path loss, or bandwidth.

[0087] In some embodiments, repeated transmissions at different time intervals or frequencies and transmissions on selected resource units (also referred to herein as "selective transmissions") may be performed so that transmissions from cell edge users may be more reliable. In a trigger frame, the AP may specify a repeated transmission or a selective transmission, as may be described later herein. In some embodiments, the criteria may be based on a path loss threshold. For example, a RA-RU may only be allocated to STAs with a path loss greater than or equal to a threshold. The criteria may be signaled in the trigger frame, which may be consistent with the embodiments described later herein. In some methods, a trigger frame may be used to trigger UL transmissions on multiple frequency bands.

[0088] This document describes embodiments involving repeated transmissions. In some repeated transmissions, a STA may transmit the same PPDU on different selected frequency (e.g., RU) or time (e.g., OFDM symbol) resources. For example, a STA may transmit the same information bits processed into different coded bits and modulation symbols on different frequency and / or time resources.

[0089] The MC information and / or repetition factor can be indicated by the AP via a trigger frame. For example, STAs can use different puncturing patterns to select coded bits, so that they can differ even within the same set of information bits. The AP can combine the energy of the entire set of selected resources or a subset of selected resources to decode the PPDU. Due to channel contention, transmissions from different STAs in an RU may partially or completely overlap or collide. In this case, the AP can discard the information in these resources and only combine the energy of resources where one or more collisions did not occur.

[0090] In some embodiments, each resource may include an Extremely High Throughput Signal X (EHT-SIG-X) field. The cyclic redundancy code (CRC) of the EHT-SIG-X field may indicate whether a collision occurred on the resource. The EHT-SIG-X field may contain the location of the resource selected by the STA to transmit on the current resource. For example, the AP may receive an EHT-SIG-X field in the first RU (i.e., RU1) indicating that repetitions are to be sent from STA1 on the first RU and the second RU (i.e., RU1 and RU2). The third RU (i.e., RU3) may include an EHT-SIG field indicating that repetitions are to be sent from STA2 on RU2 and RU3. When decoding the PPDUs of STA1 and STA2, the AP may discard the contents of RU2.

[0091] In some embodiments, repeated transmissions can be performed in the frequency domain. For example, a STA can select more than one RU and send data on each of the selected RUs. The data sent on each selected RU can be the same. There may be a minimum distance between the selected RUs to meet the power spectral density constraint. The AP can indicate this minimum distance (i.e., frequency distance) between the RUs and / or signal the RU selection constraint for the transmission of the STA. The constraint can limit the possible association between two RUs, the possible association between a single RU and a subset of RUs, or the possible association between a RU and a subset of a single RU. For example, the AP can signal that RU3 is associated with RU1 and RU5. If the STA transmits on RU3, it may also transmit on RU1 or RU5 if it needs to select, for example, a second RU.

[0092] In some embodiments, repeated transmissions may be performed in the time domain. For example, the AP may allocate RUs with reference to previous time / frequency resources in which a collision has occurred. Only one or more STAs transmitting on the designated time / frequency resources may use the subsequent RU allocations. In the first RU RA-RU1, at time t1, the AP may decode the EHT-SIG-X of the random access transmission from the STA, but may not be able to decode the data carried in the PPDU due to a collision or other reasons such as fading. The AP may indicate the RU (e.g., RU1, t1) or the ID of the STA (if it is also carried in the EHT-SIG-X) through another trigger frame. The AP may thereby assign the resources within which the STA may transmit the PPDU.

[0093] In another example involving a first and second STA, at time t1, in RA-RU1, STA1 and STA2 may perform a transmission. The AP may not be able to decode the transmission from either the first or second STA. The AP may reference the resources (e.g., RU1, t1) via a later trigger frame and assign N>1 resources, where only the STAs that previously transmitted on RU1 at t1 (i.e., STA1 and STA2) may use a subset of the N resources for retransmission.

[0094] This document describes embodiments involving repeated transmission configurations. In some embodiments, the number of repetitions sent by each STA may be fixed or configurable. One or more of the following methods may be implemented. In some methods, the number of repetitions may be predefined. For example, the number of repetitions may be predetermined by the AP, and the AP may signal the predetermined number of repetitions to one or more STAs in a control or management frame (e.g., a trigger frame). In some methods, the number of repetitions may depend on the type of service. For example, services with low latency requirements may be allowed to have more repeated transmissions. This may be facilitated, for example, by using multiple RUs. Services with high reliability requirements may be allowed to have more repeated transmissions. The mapping between service type / QoS parameters and the number of allowed repeated transmissions may be predefined, predetermined, or signaled by the AP to one or more STAs. The STA may determine the number of repeated transmissions by checking its service type and the corresponding mapping.

[0095] In some methods, the number of repeated transmissions may depend on the path loss and the target RSSI. For example, when using maximum transmit power, the STA may not be able to achieve the target UL RSSI, and the STA may be allowed to perform one or more repeated transmissions. In some methods, the number of repeated transmissions that can be performed may depend on the amount by which the estimated received power falls below the target. For example, if the estimated received power on the AP side is 3dB (or within 3dB) below the UL target RSSI, the STA may be allowed to perform two repeated transmissions. In another example, if the estimated received power on the AP side is 6dB (or within 6dB) below the UL target RSSI, the STA may be allowed to perform four repeated transmissions.

[0096] Embodiments involving RU selection for transmission are described herein. When the OFDMA backoff (OBO) counter is not greater than the number of eligible RUs, an RU may be randomly selected from the eligible RUs for transmission. In other embodiments, the transmitting RU may be selected based on channel conditions to meet the target RSSI indicated by the AP. The channel conditions may be based on one or more channel measurements on the RU, such as reference signal received power (RSRP), or one or more of the maximum singular values ​​of a singular value decomposition of the channel on the RU.

[0097] In an example scenario, upon receiving a trigger frame, the STA may rank the M eligible RA-RUs from best to worst 1, ..., M based on the channel conditions. The STA may perform a series of N retransmissions. In the first transmission, the STA may randomly select an RU from the eligible RUs whose corresponding ranking is in set S1. The STA may perform selection from a different set for subsequent retransmissions, which may be a superset of S1. For example, in the (N-1)th retransmission, the STA may select an RU from the eligible RUs whose corresponding ranking is in set S1. N An RU is randomly selected from the eligible RUs in the RU set. For example, in the first transmission, the STA can select the RU with the best channel condition to minimize the error. If the first transmission fails, the STA can select an RU from the RU set that includes the best RU and the second best RU. This can avoid the situation where two STAs select one RU as the best RU and experience a collision again during retransmission. The ranking of RUs may or may not change in each retransmission, depending on the degree of Doppler shift and spread. The value of M can be different for each retransmission, depending on the number of eligible resources or RUs allocated for each retransmission.

[0098] In one example, where s1 = {1}, s2 = {2}, ..., the RA-STA may select the best RU for initial transmission and the second best RU for the first retransmission. In another example, where s1 = {1}, s2 = {1, 2, 3}, the RA STA may select the best RU for initial transmission and may randomly select one of the best RU, the second best RU, or the third best RU for the first retransmission based on, for example, ranking.

[0099] This document describes an embodiment involving performing channel measurements based on a PPDU carrying a trigger frame. In some embodiments, the trigger frame can be sent to more than one STA. To avoid unexpected beamforming, cyclic delay diversity (CDD) can be used for an AP with multiple antennas that transmit PPDUs using a single stream. The method in the previous section may require the STA to estimate the channel conditions on different RUs. For non-AP STAs using a single antenna, CDD may cause frequency selective fading. This may prevent the STA from correctly estimating the channel conditions because the STA may not be taking advantage of channel reciprocity.

[0100] For non-AP STAs using multiple antennas, CDD with single-stream transmissions may prevent the STA from estimating the channel, performing SVD decomposition of the estimated channel, and using the decomposition results to precode beamformed transmissions. To address this issue, the PPDU carrying the trigger frame can have more than one channel estimation sequence, and the number of sequences can correspond to the number of antennas at the AP. For example, each LTF sequence can correspond to a transmit antenna of the AP, and the LTF sequence can be added to the PPDU carrying the trigger frame. This is applicable to PPDUs transmitted using a single spatial stream or using CDD. To decode the PPDU carrying the trigger frame, single-stream channel estimation for each receive antenna can be performed by combining the channels estimated from all the sequences at that receive antenna.

[0101] This document describes embodiments involving adjustment of the target RSSI level. In some methods, a subfield in the User Information field may be defined to indicate that the UL target RSSI must be met. For example, the new subfield may be a one-bit field named "Target RSSI Command." In some configurations, STAs that cannot achieve the UL target RSSI may be unable to transmit or may lack permission to transmit. For example, when the AID12 subfield in the User Information field is not 0 or 2045, a dedicated trigger may be indicated. In this case, the AP and STA procedures may proceed as follows. Based on a priori information, the AP may know the STA's path loss. The AP may group the STA with other STAs with similar path loss and send a trigger frame to trigger UL transmission for this group of STAs. The AP may set the UL target RSSI based on its estimated path loss. In one method, the group of STAs may be identified by a group AID, which may be carried in the AID12 field. Both the AP and the STA may know the group AID before trigger-based transmission. For example, the AP may assign the group AID to the group of STAs in a control frame, management frame, or data frame.

[0102] A STA whose AID matches the AID12 subfield in the trigger frame can estimate whether it can achieve the UL target RSSI carried in the trigger frame. The STA can check whether the target RSSI command field is set. If the target RSSI command field is set and the STA can achieve the UL target RSSI, the STA can adjust its transmit power and perform transmission in the allocated one or more RUs. If the target RSSI command field is set and the STA cannot achieve the UL target RSSI, the STA may not transmit in the allocated one or more RUs. In an alternative method, the STA can transmit only the PLCP header at its maximum transmit power or the entire bandwidth or at a power that can produce the closest target RSSI in the allocated one or more RUs, so that the AP can implicitly know that the STA may not be able to achieve the target RSSI. Assuming that the STA uses maximum power transmission, the AP can use the PLCP header transmitted in the assigned RU to estimate the path loss of the STA.

[0103] If the Target RSSI Command field is not set and the STA is able to achieve the UL target RSSI, the STA may adjust its transmit power and transmit in the allocated one or more RUs. If the Target RSSI Forced field is not set and the STA may not be able to achieve the UL target RSSI, the STA may use its maximum transmit power or may generate a power closest to the target RSSI and transmit in the allocated one or more RUs. In some cases, the AP may not receive uplink transmissions and may regroup the one or more STAs based on a lower RSSI level. The AP may lower the UL target RSSI in subsequent trigger frames. In some embodiments, the AP may have recorded the estimated RSSIs of all associated STAs in a table, and the AP may frequently update the table.

[0104] For example, a random trigger may be indicated when the AID12 subfield in the User Information field is 0 or 2045. In this case, the AP and STA procedures may proceed as described in the following embodiments. In some examples, the AP may prepare a set of trigger frames sequentially in time. The AP may prepare a set of UL target RSSIs in descending order. In the first trigger frame of the sequence, the AP may use the first UL target RSSI. The AP may set the Target RSSI Command subfield in all trigger frames of the sequence. The AP may use a field to indicate that the trigger frame is part of a sequence of trigger frames.

[0105] A STA that is allowed to perform UL OFDMA-based random access (also known as a RA-STA) may check whether it has transmitted a response to any trigger frame in the trigger frame sequence. If yes, the STA may not send anything. If not, the STA may estimate whether it can achieve the UL target RSSI carried in the trigger frame. If the STA can achieve the UL target RSSI, the STA may adjust its transmit power and perform transmission in the allocated one or more RUs. If the STA cannot achieve the UL target RSSI, the STA may not transmit in the allocated one or more RUs. In an alternative method, the STA may transmit only the PLCP header at its maximum transmit power or at a power that can produce the closest target RSSI in the entire bandwidth or the allocated one or more RUs, so that the AP may implicitly know that the STA cannot achieve the target RSSI. Assuming that the STA transmits the PLCP header at maximum power, the AP can use the PLCP header transmitted in the assigned RU to estimate the path loss of the STA. The AP may continue to send the next trigger frame in the sequence with the next corresponding UL target RSSI.

[0106] This document describes embodiments related to the implementation of a multi-band trigger frame (MBTF). In some solutions, the trigger frame can be allocated to RA-RUs in higher frequency bands such as the 5 / 6 GHz band and lower frequency bands such as the 2.4 GHz band, although it is conceivable that RA-RUs can be allocated in any other valid frequency band. The PPDU or PPDUs carrying the trigger frame can occupy higher frequency band channels and lower frequency band channels to facilitate channel / path loss estimation by non-AP STAs for different frequency bands.

[0107] In some embodiments, each RA-STA can calculate the maximum expected RSSI (ERSSI) in the higher frequency band at the AP based on the path loss estimate in the higher frequency band and its maximum transmit power. If the ERSSI is less than the target RSSI (TRSSI) in the higher frequency band indicated in the trigger frame for STAs using time-sensitive applications (e.g., applications with low latency requirements, such as online gaming), the STA can have priority for selecting RUs in the 2.4 GHz band. If the STA can meet the TRSSI, it can have only a fraction x of the total lower frequency band RUs as qualified RUs. The difference between the ERSSI and TRSSI can be the power headroom in the higher frequency band. Even if the power headroom in the higher frequency band is positive, a STA with a small headroom may still need to utilize a lower frequency band RU due to power amplifier nonlinearity. For example, the number of qualified lower frequency band RA-RUs or the fraction x of the total lower frequency band RA-RUs can be defined by function f1. As described herein, f1 may be a function of the ERSSI, the TRSSI, a combination of the ERSSI and TRSSI (as a power headroom), priority, MCS, number of RA-RUs in the upper band, number of RA-RUs in the lower band, or other metrics.

[0108] Figure 2 is an example representation of eligible RUs for each of the two categories of RA-STAs. As shown, a RA-STA can be associated with either priority 1 or 2, where a STA associated with priority 1 can have greater access to lower-band RUs than a STA associated with priority 2. The available proportion, fraction, or percentage x of the total lower-band RUs can vary depending on the power headroom, the TRSSI, and the calculated ERSSI. In cases where the power headroom is low or negative, such that the STA's ERSSI does not exceed the TRSSI, the proportion of available lower-band RUs can be greater. In cases where the STA's power headroom is such that the ERSSI meets or exceeds the TRSSI, the proportion of available lower-band RUs can be reduced, such that a priority 2 STA has fewer available lower-band RUs, or no available lower-band RUs. Similarly, a priority 1 STA whose power headroom is such that the ERSSI meets or exceeds the TRSSI can have fewer available lower-band RUs, but a greater number of available lower-band RUs than a priority 2 STA whose ERSSI exceeds the TRSSI.

[0109] Similarly, another function f2 can be used to designate a proportion, fraction, or percentage y of the higher-band RUs as "qualified RUs." For example, if the power headroom in the higher band is less than or equal to 0, then y can be equal to 0. As described herein, f2 can be a function of the ERSSI, the TRSSI, a combination of the ERSSI and TRSSI (as the power headroom), priority, MCS, the number of RA-RUs in the higher band, the number of RA-RUs in the lower band, or other metrics.

[0110] Figure 3 is an example representation of eligible RUs for each of the two classifications of RA-STAs. Similar to the above, a RA-STA can be associated with either priority 1 or 2. In the case where the power headroom is low such that the STA's ERSSI does not exceed the TRSSI, neither the priority 1 STA nor the priority 2 STA may access the higher band RUs. In the case where the power headroom of the STA is such that the ERSSI meets or exceeds the TRSSI, the proportion of available higher band RUs may be increased so that the STA has a larger proportion of available higher band RUs. A priority 1 STA whose power headroom is such that the ERSSI meets or exceeds the TRSSI may have increased access to higher band RUs as the power headroom increases, while a priority 2 STA may have a constant proportion of available higher band RUs regardless of the amount by which the ERSSI exceeds the TRSSI.

[0111] The total number of eligible RUs in the lower band can be expressed as N l =f(N lower ×x) Equation 1 where N lower is the total number of lower band RA-RUs that a STA is allowed to access. Similarly, the total number of eligible RUs in the higher band can be expressed as N u =f(N upper ×y) Equation 2 where n upper is the total number of higher-band RA-RUs that the STA is allowed to access. In both equations, f can be an integer conversion function such as taking the ceiling or floor. Once x and y are determined, the precise location of the eligible RU can be calculated based on N l and N u The exact location of the eligible RU is randomly selected from the total RA-RUs in each band, i.e., randomly from N lower Select N out of RUs l RUs and / or randomly from N upper Select N out of RUs uAs an alternative, the qualified RUs can be selected based on the channel conditions of one or more RUs. For example, when determining the lower band qualified RUs, the N RUs with the best path loss in terms of the STA being allowed to access can be selected. l RA-RUs are selected as eligible RUs in the lower frequency band. The STA can then follow the current OBO counter decrement rule as described above to perform a backoff procedure when the OBO counter is greater than the number of eligible RUs, or select a final transmitting RU from the eligible RUs when the OBO counter is not greater than the number of eligible RUs.

[0112] Figure 4A Another diagram of a multi-band trigger frame embodiment is described, which includes five STAs 411, 412, 413, 414, and 415 and a multi-band AP 401. STAs 411, 412, 413, 414, and 415 can be located at different distances from the multi-band AP 401, as shown by their respective positions relative to AP 401. STAs 411, 412, and 413 are priority 1 STAs, while STAs 414 and 415 are priority 2 STAs. As shown in the figure, qualified RUs for each STA are determined for the high and low bands, respectively. The distance at which a STA can achieve TRSSI for the low band may be greater than the distance at which a STA can achieve TRSSI. For example, STAs 411 and 415 may be able to achieve TRSSI for the low band RUs, but not for the high band RUs. Since STA 411 is a priority 1 STA, it can access a greater number of low band RUs than STA 415 (a priority 2 STA). In contrast, STAs 413 and 414 may be located at a smaller distance from AP 401 and may have a greater proportion of the total high-band RUs available. In this example, STAs 411 and 415 may monitor transmissions from the AP only on the lower frequency bands due to limited coverage.

[0113] Figure 4B The low-band RA-RU eligibility of STAs 411, 412, 413, 414, and 415 is depicted relative to the high-band TRSSI. As described above, STAs 411 and 415 may not meet the TRSSI of the high-band RU and, therefore, may be provided with greater access to the low-band RU. STAs 412, 413, and 414 are able to exceed the TRSSI of the high-band RU, and may, in general, have access to fewer low-band RUs. Priority 1 STAs 412 and 413 may have greater access to the low-band RU than priority 2 STA 414.

[0114] Figure 5An example method is shown in which an AP can optimize the allocation and selection of RA-RUs within multiple frequency bands. At 501, the AP can allocate several low-band RUs and several high-band RUs for random access by one or more STAs. The low-band RUs can be used by STAs in a larger coverage area, while the high-band RUs can be used by STAs in a relatively smaller coverage area. The number of RUs available for each STA can depend on one or more metrics, such as ERSSI, power headroom, TRSSI, priority, MCS, or the total number of RUs in the low and high bands. At 502, the AP can send a PLCP protocol data unit (PPDU), which can include a trigger frame indicating the allocated RUs at the high and low bands. The trigger frame can also include, for example, one or more of the following: TRSSI, a priority corresponding to one or more STAs, an identifier field associated with one or more STAs, or an identifier indicating associated or unassociated random access. The PPDU can include one or more channel estimation sequences corresponding to the transmit antennas of the AP. The trigger frame may be carried in a PPDU on one or both of the low and high frequency bands, and the PPDUs may or may not be sent exactly at the same time. At 503, the AP may receive a message from one or more STAs. The message may be a random access message, instructing the STA to complete a random access procedure, or may be an indication that the STA cannot achieve the TRSSI, for example.

[0115] Figure 6 is a corresponding example of a random access method performed by a STA. At 601, a STA may receive a PPDU including a trigger frame from an AP. The trigger frame may indicate a number of low-band RUs and a number of high-band RUs in which messages are sent via a higher or lower frequency band. The trigger frame may include a TRSSI corresponding to the higher or lower frequency band. At 602, upon receiving the trigger frame, the STA may perform path loss estimation for the low-band and / or high-band. The STA may calculate the corresponding ESSRI at the AP. The STA may determine the power headroom for transmitting one or more random access messages. At 603, the STA may select an RU from the low-band or high-band based on the ERSSI, TRSSI, and power headroom to transmit the one or more random access messages. The STA may determine, for example, whether it can meet the TRSSI based on the determined power headroom. At 604, the STA may transmit the message on the selected RA-RU in the low-band or high-band RU.

[0116] Because the wireless medium busyness is different between different channels or frequency bands, the AP may not be able to send a PPDU carrying a trigger frame on both the high and low frequency bands at the same time. In this case, the AP may provide an indication in an earlier trigger frame to indicate to one or more STAs that the STA will soon receive another trigger frame in another frequency band. This can prevent the STA from making backoff and random access decisions based solely on the resources or TRSSI assigned in the frequency band in which the earlier trigger frame was received. For example, when using the Enhanced Distributed Channel Access (EDCA) procedure, a trigger frame in a first frequency band (i.e., a 2.4 GHz band) may be sent first, and a trigger frame in a second frequency band (i.e., a 5 GHz band) may be sent later. For example, in a 2.4 GHz trigger frame, the AP may indicate that another trigger frame will be sent in the 5 GHz band, and one or more STAs may need to evaluate the 5 GHz channel conditions to determine whether they should access the 2.4 GHz RA-RU. If the channel conditions allow the STA to perform random access in the 5 GHz band, the STA may wait for the 5 GHz trigger frame to perform access and provide more access opportunities for other STAs located in the poorer coverage area to perform access on the 2.4 GHz band. In addition, the earlier trigger frame in the first band may indicate the TRSSI, the number of RA-RUs, or the MCS to be assigned to the RA-RU in the trigger frame sent later in the second band. The STA monitoring and receiving on the two bands may maintain measurements of the RSSI of the APs on the two bands. Based on the information from the earlier trigger frame at the first band, the STA may use the process as described in the previous paragraph to determine whether its access should be performed in the lower or higher band, or in neither the lower or higher band, for example, if the OBO counter is greater than the combined qualified RUs in the two bands.

[0117] While the solutions described herein may consider 802.11 specific protocols, it will be appreciated that the solutions described herein are not limited to these scenarios and may also be applied to other wireless systems. Although features and elements are described above in specific combinations, it will be understood by those skilled in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware embedded in a computer-readable medium and executed by a computer or processor. 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 memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROMs and digital versatile disks (DVDs). A processor associated with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A station (STA), comprising: a processor and a transceiver configured to receive a trigger frame in one of a higher frequency band or a lower frequency band, wherein the trigger frame includes information indicating a plurality of resources, wherein each resource of the plurality of resources is associated with one of the higher frequency band or the lower frequency band; The processor is configured to select one of the plurality of resources; and The processor and the transceiver are configured to transmit a physical layer convergence procedure (PLCP) protocol data unit (PPDU) using the selected resources. 2 . The STA of claim 1 , wherein the trigger frame includes an indication of a target received signal strength indicator (TRSSI) associated with the higher frequency band or the lower frequency band.

3. The STA of claim 1, wherein the processor is configured to calculate an expected received signal strength indicator (ERSSI). 4 . The STA of claim 3 , wherein the processor is configured to calculate the ERSSI based on a path loss estimate associated with the higher frequency band or the lower frequency band and based on a maximum transmit power of the STA. 5 . The STA according to claim 4 , wherein the lower frequency band is a 2.4 GHz frequency band, and the higher frequency band is a 5 GHz or higher frequency band.

6. A station (STA), comprising: a processor and a transceiver configured to receive a trigger frame including an indication of resources for uplink traffic; The processor and the transceiver are configured to determine channel conditions associated with the indicated resources for uplink traffic; The processor and the transceiver are configured to select the indicated subset of resources based on the determined channel conditions; as well as The processor and the transceiver are configured to transmit a physical layer convergence procedure (PLCP) protocol data unit (PPDU) using the selected subset of the indicated resources.

7. The STA according to claim 6, wherein: The selected subset of the indicated resources is selected based on a ranking of the indicated resources.

8. The STA according to claim 6, wherein: The selected subset of the indicated resources is ranked based on the determined channel conditions.

9. The STA of claim 6, the processor and the transceiver configured to transmit another PPDU using another selected subset of the indicated resources.

10. The STA according to claim 6, wherein: The another selected subset of the indicated resources is selected randomly.

11. A station (STA), comprising: a processor and a transceiver configured to receive a trigger frame including an indication of a repetition factor; The processor and the transceiver are configured to transmit a first physical layer convergence procedure (PLCP) protocol data unit (PPDU) using a first resource based on the indication regarding the repetition factor; as well as The processor and the transceiver are configured to transmit a second PPDU using second resources based on the indication of the repetition factor, wherein the first PPDU includes first coded bits and modulated symbols, and wherein the second PPDU includes second coded bits and modulated symbols different from the first coded bits and modulated symbols, and wherein the first PPDU and the second PPDU include the same information. 12 . The STA of claim 11 , wherein the first resource comprises a first frequency resource, and the second resource comprises a second frequency resource different from the first frequency resource. 13 . The STA of claim 11 , wherein the first resource comprises a first time resource, and the second resource comprises a second time resource different from the first time resource. The STA of claim 11 , wherein the trigger frame includes an indication of a number of repetitions. The STA according to claim 11 , wherein the trigger frame includes an indication of a delay requirement.

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