TW201713088A - Methods for resource allocation of an OFDMA WLAN system - Google Patents

Abstract

Systems, methods, and instrumentalities are disclosed for SIG Design for OFDMA in WLAN Systems. A protocol data unit (PDU),e.g., a medium access control (MAC) PDU, may be transmitted. Data may be mapped to a plurality of OFDM symbols of the PDU. Each of the plurality of OFDM symbols may be associated with a first duration and a first length of data. A second length of data to be transmitted in a last OFDM symbol of the plurality of OFDM symbols may be determined to be less than the first length of data. The last OFDM symbol may be modified, for example, based on the second length of data, from the first duration to a second duration. The second duration may be 1/4, 1/2, or 3/4 of the first duration. An indication of the second duration of the last OFDM symbol may be sent.

Description

OFDMA WLAN system resource allocation method

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No The content is hereby incorporated by reference.

A wireless local area network (WLAN) can have multiple modes of operation, such as an infrastructure basic service set (BSS) mode and/or an independent BSS (IBSS) mode. A WLAN in an infrastructure BSS mode may have an access point (AP) for a BSS. One or more wireless transmit and receive units (WTRUs), such as stations (STAs), may be associated with the AP. The AP may have a distribution system (DS) or other type of access and/or interface that carries wired/wireless networks within the BSS and outside of the BSS. The traffic from the outside of the BSS to the STA can be reached through the AP, which can transmit the traffic to the STA. In some WLAN systems, STA to STA communication can occur. In some WLAN systems, an AP can play the role of an STA. The WLAN device can use beamforming. Existing beamforming techniques may be limited. Resources can be allocated in the WLAN.

Systems, methods and tools for dynamic encapsulation are disclosed, such as orthogonal frequency division multiple access (OFDMA) in WLAN systems. Protocol Data Units (PDUs), such as Media Access Control (MAC) PDUs, can be transmitted. The PDU may be a Physical Layer Convergence Procedure (PLCP) PDU (PPDU). The data can be mapped to multiple OFDM symbols of the PDU. Each of the plurality of OFDM symbols can be associated with a first duration and/or a first length of material. The first length of the data may be associated with a length of data (eg, a maximum data length) carried within each of the plurality of OFDM symbols. The second length of the material transmitted in the last OFDM symbol of the plurality of OFDM symbols may be determined to be less than the first length. For example, the second length of the material can be determined to be 1⁄4, 1⁄2 or 3⁄4 of the first length of the material. The last OFDM symbol can be modified from the first duration to a second duration, for example, based on the second length of the data. The second duration can be 1⁄4, 1⁄2 or 3⁄4 of the first duration. When the second length of the material is less than or equal to 1⁄4 of the first length of the material, the last OFDM symbol can be modified to 1⁄4 of the first duration. When the second length of the material is greater than 1⁄4 of the first length of the material and less than or equal to 1⁄2 of the first length of the material, the last OFDM symbol can be modified to 1⁄2 of the first duration. When the second length of the material is greater than 1⁄2 of the first length of the material and less than or equal to 3⁄4 of the first length of the material, the last OFDM symbol can be modified to 3⁄4 of the first duration. The first length of the data and/or the second length of the data may be associated with a plurality of available carriers.

An indication of the second duration of the last OFDM symbol can be transmitted. The indication may indicate that the second duration of the last OFDM symbol is 1⁄4, 1⁄2 or 3⁄4 of the first duration. The indication of the second length of the last OFDM symbol can be indicated as 1⁄4, 1⁄2 or 3⁄4 via the PHY header or MAC header. The indication may indicate that the second duration is equal to the first duration when the second length of the data is greater than 3⁄4 of the first length of the data. A periodic symbol can be generated based on the second length of the last OFDM symbol. By removing too much padding using a Fast Fourier Transform (FFT) / Inverse FFT (IFFT) relationship, the last OFDM symbol can be reduced from the first length to the second length. Modifying the last OFDM symbol from the first duration to the second duration may include removing one or more redundancy periods due to the use of the IFFT relationship.

The detailed description of the exemplary embodiments will be described with reference to the accompanying drawings.

Figure 1A shows an exemplary wireless local area network (WLAN) device. One or more devices can be used to implement one or more of the features described herein. The WLAN may include, but is not limited to, an access point (AP) 102, a station (STA) 110, and a station 112. Stations 110 and 112 can be associated with AP 102. The WLAN may be configured to implement one or more IEEE 802.11 communication standard protocols, which may include channel access schemes such as DSSS, OFDM, OFDMA, and the like. The WLAN can operate in modes such as infrastructure mode, ad-hoc mode, and the like.

A WLAN operating in infrastructure mode may include one or more APs in communication with one or more associated STAs. The AP and the STA(s) associated with the AP may include a Basic Service Set (BSS). For example, AP 102, station 110, and station 112 can include BSS 122. An extended service set (ESS) may include one or more APs (having one or more BSSs) and STAs (one or more) associated with the APs. The AP may have access and/or interfaces to a distribution system (DS) 116, which may be wired and/or wireless and may be carried to and/or carry traffic from the AP. Traffic originating from the WLAN outside the WLAN to the STA in the WLAN may be received at the AP in the WLAN, which may send the traffic to the STAs in the WLAN. Traffic originating from STAs in the WLAN to destinations other than the WLAN (e.g., to the server 118) can be sent to the AP in the WLAN, which can send the traffic to the destination, such as via the DS 116 to the network 114. It is sent to the server 118. The traffic between STAs in the WLAN can be sent through one or more APs. For example, a source STA (e.g., STA 110) may have traffic for a destination STA (e.g., STA 112). The STA 110 can send traffic to the AP 102, and the AP 102 can send traffic to the STA 112.

The WLAN can operate in ad-hoc mode. The ad-hoc mode WLAN may be referred to as an Independent Basic Service Set (IBBS). In an ad-hoc mode WLAN, STAs can communicate directly with one another (e.g., STA 110 can communicate with STAs 112 without the need for communication routed through the AP).

An IEEE 802.11 device (eg, an IEEE 802.11 AP in a BSS) can use a beacon frame to announce the presence of a WLAN network. An AP, such as AP 102, can transmit a beacon on a channel (eg, a fixed channel, such as a primary channel). The STA can establish a connection with the AP using a channel such as a primary channel.

The STA (one or more) and/or AP(s) may use a Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) channel access mechanism. In CSMA/CA, STAs and/or APs can listen to the primary channel. For example, if the STA has data to send, the STA can listen to the primary channel. If the primary channel is detected to be busy, the STA can roll back. For example, a WLAN or portion thereof can be configured such that one STA can be transmitted at a given time, such as in a given BSS. Channel access can include RTS and/or CTS messaging. For example, an exchange of a transmission request (RTS) frame may be transmitted by a transmitting device, and a clear to send (CTS) frame may be transmitted by the receiving device. For example, if the AP has data to send to the STA, the AP may send an RTS frame to the STA. If the STA is ready to receive data, the STA can respond with a CTS frame. The CTS frame may include a time value that may alert other STAs to defer access to the medium when the AP that initialized the RTS may transmit its data. Upon receiving the CTS frame from the STA, the AP may send the data to the STA.

The device can reserve the spectrum via a Network Allocation Vector (NAV) field. For example, in the IEEE 802.11 frame, the NAV field can be used to reserve a channel for a time period. STAs wishing to transmit data can set the time at which the NAV may wish to use the channel. When the STA sets the NAV, the NAV can be set for the associated WLAN or a subset thereof (eg, BSS). Other STAs can count down NAV to 0. When the counter reaches a value of 0, the NAV function can indicate that other STAs are now available.

A device in a WLAN, such as an AP or a STA, may include one or more of the following: a processor, a memory, a wireless receiver/transmitter (eg, which may be incorporated in a transceiver), one or more antennas ( For example, the antenna 106) in Fig. 1A and the like. A processor function can include one or more processors. For example, the processor may include a general purpose processor, a special purpose processor (eg, a baseband processor, a MAC processor, etc.), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array ( One or more of an FPGA) circuit, any other type of integrated circuit (IC), state machine, and the like. One or more processors may or may not be integrated with one another. A processor (eg, one or more processors or a subset thereof) can be integrated with one or more other functions, such as other functions such as memory. The processor may perform signal decoding, data processing, power control, input/output processing, modulation, demodulation, and/or any other functionality that enables the device to operate in a wireless environment (eg, WLAN of FIG. 1A). The processor can be configured to execute processor executable code (eg, instructions) including, for example, software and/or firmware instructions. For example, the processor can be configured to execute one or more processors (eg, a chipset containing memory and a processor) or computer readable instructions embodied in the memory. Execution of the instructions may cause the device to perform one or more of the functions described herein.

The device can include one or more antennas. The device can employ multiple input multiple output (MIMO) technology. One or more antennas can receive radio signals. The processor can receive radio signals, such as via one or more antennas. One or more antennas may transmit radio signals (eg, based on signals transmitted from the processor).

The device can have a memory that includes one or more programs for storing programs and/or data (eg, processor executable code or instructions (eg, software, firmware, etc.), electronic materials, databases, or other digits). Information) device. The memory can include one or more storage units. One or more storage units may be integrated with one or more other functions, such as other functions included in a processor device. The memory may include read only memory (ROM) for storing information (eg, erasable programmable read only memory (EPROM), electrically erasable programmable memory (EEPROM), etc.), random memory ( RAM), disk storage media, optical storage media, flash memory devices, and/or other non-permanent computer readable media. The processor can communicate with one or more memory entities, such as via a system bus, directly, and the like.

FIG. 1B is a diagram of an exemplary communication system 100 that can implement one or more of the disclosed features. For example, a wireless network (eg, a wireless network including one or more components of communication system 100) can be configured to extend beyond a wireless network (eg, a walled garden associated with a wireless network) The bearer of the outer) can be assigned a QoS characteristic.

Communication system 100 may be a multiple access system that provides content to a plurality of wireless users, such as voice, data, video, messaging, broadcast, and the like. The communication system 100 allows multiple wireless users to access such content by sharing system resources including wireless bandwidth. For example, communication system 100 can 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 frequency division multiple memory. Take (OFDMA), Single-Carrier Frequency Division Multiple Access (SC-FDMA), and so on.

As shown in FIG. 1B, communication system 100 can include at least one wireless transmit/receive unit (WTRU), such as multiple WTRUs, such as WTRUs 102a, 102b, 102c, and 102d, a wireless access network (RAN) 104, a core network. Path 106, Public Switched Telephone Network (PSTN) 108, Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements . Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and/or receive wireless signals and may include user equipment (UE), mobile stations (eg, WLAN STAs), fixed or mobile subscriber units, pagers , mobile phones, personal digital assistants (PDAs), smart phones, laptops, portable Internet devices, personal computers, wireless sensors, consumer electronics and more.

Communication system 100 can also include base station 114a and base station 114b. Each of the base stations 114a and 114b can be any type of device configured to have access to one or more communication networks through a wireless interface with at least one of the WTRUs 102a, 102b, 102c, 102d (the communication network) Such as core network 106, internet 110, and or network 112). By way of example, base stations 114a, 114b may be base transceiver stations (BTS), Node Bs, eNodeBs, home Node Bs, home evolved Node Bs, base controllers, access points (APs), wireless routers, and the like. While each of the base stations 114a, 114b is depicted as a separate component, it should be understood that the base stations 114a, 114b can include any number of interconnected base stations and/or network elements.

The base station 114a may be part of the RAN 104, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay. Nodes and so on. Base station 114a and/or base station 114b may be configured to transmit and/or receive wireless signals within a particular geographic area, which is referred to as a cell (not shown). Cells can be further divided into cell sectors. For example, a cell associated with base station 114a can be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, that is, one for each of the cells. In another embodiment, base station 114a may use multiple input multiple output (MIMO) technology, and thus multiple transceivers may be used for each sector of a cell.

The base stations 114a, 114b may communicate with one or more of the wireless transmit/receive units WTRUs 102a, 102b, 102c, 102d via an empty intermediation plane 116, which may be any suitable wireless communication link (eg, radio frequency (RF) ), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The empty mediation plane 116 can be established using a suitable radio access technology (RAT).

More specifically, as previously mentioned, communication system 100 can be a multiple access system and can employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, base station 114a and wireless transmit/receive unit WTRUs 102a, 102b, 102c in RAN 104 may perform radio technologies, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), and the technology may use wideband CDMA ( WCDMA) establishes an empty intermediary plane 116. WCDMA may include communication protocols such as High Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High Speed Downlink Packet Access (HSDPA) and/or High Speed Packet Uplink Packet Access (HSUPA).

In another embodiment, the base station 114a and the wireless transmit/receive unit WTRUs 102a, 102b, 102c may implement a radio technology, such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may use Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) to establish an empty media plane 116.

In other embodiments, base station 114a and wireless transmit/receive unit WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.16 (Worldwide Interoperability for Microwave Access (WIMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile Communications (GSM), GSM Enhanced Data Rate Evolution (EDGE), GSM EDGE (GERAN) )and many more.

As an example, base station 114b in FIG. 1B may be a wireless router, a home Node B, a home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, Housing, transportation, campus, etc. In one embodiment, base station 114b and WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, base station 114b and WTRUs 102c, 102d may implement wireless technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In another embodiment, base station 114b and WTRUs 102c, 102d may establish picocells or femtocells using a cell based RAT (eg, WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.). As shown in FIG. 1B, the base station 114b can be directly connected to the Internet 110. Therefore, the base station 114b does not need to access the Internet 110 through the core network 106.

The RAN 104 can communicate with the core network 106, which can be configured to provide voice, data, application, and/or internet protocol voice (VOIP) to one or more of the WTRUs 102a, 102b, 102c, 102d. ) Any type of network that serves. For example, core network 106 may provide call control, billing services, mobile location based services, prepaid calling, internet connectivity, video distribution, etc., and/or perform advanced security functions such as user authentication. Although not shown in FIG. 1B, it should be appreciated that the RAN 104 and/or the core network 106 can communicate directly or indirectly with other RANs that use the same or different RATs as the RAN 104. For example, in addition to being connected to the RAN 104 using E-UTRA radio technology, the core network 106 can also communicate with other RANs (not shown) employing GSM wireless technology.

The core network 106 can 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 interconnected computer network and device system using a public communication protocol, which may be TCP in the Transmission Control Protocol (TCP)/Internet Protocol (IP) Internet Protocol family, User Datagram Protocol (UDP) and IP. Network 112 may include a wired or wireless communication network that is owned and/or operated by other service providers. For example, network 112 may include another core network connected to one or more RANs, which may use the same or a different RAT as RAN 104.

Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities, in other words, the WTRUs 102a, 102b, 102c, 102d may include multiple communications with different wireless networks over different wireless links. transceiver. For example, the WTRU 102c, as shown in FIG. 1B, can be configured to communicate with a base station 114a that uses a cell-based radio technology, and with a base station 114b that can use an IEEE 802 radio technology.

FIG. 1C depicts an exemplary wireless transmit/receive unit WTRU 102. The WTRU may be a User Equipment (UE), a mobile station, a WLAN STA, a fixed or mobile subscriber unit, a pager, a mobile phone, a personal digital assistant (PDA), a smart phone, a laptop, an internet laptop, a personal Computers, wireless sensors, consumer electronics, etc. The WTRU 102 may be used with one or more of the communication systems described herein. As shown in FIG. 1C, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive unit 122, a speaker/microphone 124, a numeric keypad 126, a display/touchpad 128, a non-removable memory 130, and a removable In addition to memory 132, power source 134, global positioning system (GPS) chipset 136, and other peripheral devices 138. It should be appreciated that the WTRU 102 may also include any sub-combination of the aforementioned components while remaining consistent with the embodiments.

The processor 118 can 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, and a dedicated Integrated circuit (ASIC), field programmable gate array (FPGA) circuits, any other type of integrated circuit (IC), state machine, and more. The processor 118 may perform signal decoding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to a transceiver 120 that can be coupled to the transmit/receive element 122. Figure 1C depicts processor 118 and transceiver 120 as separate components, but it should be understood that processor 118 and transceiver 120 can be integrated into an electronic component or wafer.

The transmit/receive element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via an empty intermediate plane 116. For example, in one embodiment, the transmit/receive element 122 can be an antenna configured to transmit and/or receive RF signals. In another embodiment, for example, the transmit/receive element 122 can be a transmitter/detector configured to transmit and/or receive IR, UV or visible light signals. In another embodiment, the transmit/receive element 122 can be configured to transmit and receive RF and optical signals. It should be appreciated that the transmit/receive element 122 can be configured to transmit and/or receive any combination of wireless signals.

Moreover, although the transmit/receive element 122 is depicted as a separate element in FIG. 1C, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may use MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) that transmit and receive wireless signals via the null intermediaries 116.

The transceiver 120 can be configured to modulate a signal to be transmitted by the transmit/receive element 122 and to demodulate a signal received by the transmit/receive element 122. As mentioned previously, the WTRU 102 is multi-mode capable, and thus, the transceiver 120 may include multiple transceivers to allow the WTRU 102 to communicate over multiple RATs such as UTRA and IEEE 802.11.

The processor 118 of the WTRU 102 can be coupled to a speaker/microphone 124, a numeric keypad 126, and/or a display/touchpad 128 (eg, a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and User input data from these components can be received. The processor 118 can also output user data to the speaker/microphone 124, the numeric keypad 126, and/or the display/touchpad 128. In addition, the processor 118 can access information in any type of memory, such as the non-removable memory 130 and/or the removable memory 132, and can store the data in these memories. Non-removable memory 130 may include random access memory (RAM), read only memory (ROM), hard disk, or any other type of storage device. 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 can access information in the memory and can store the data in the memory, the memory not being physically disposed on the WTRU 102, such as on a server or a home computer ( Not shown).

The processor 118 can receive power from the power source 134 and can be configured to distribute power to other components of the WTRU 102 and control power to other components of the WTRU 102. Power source 134 can be any device suitable for powering WTRU 102. For example, the power source 134 can include one or more dry battery packs (eg, nickel chromium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like. .

Processor 118 may also be coupled to GPS chipset 136, which may be configured to provide positioning information (e.g., longitude and latitude) with respect to the current location of WTRU 102. The WTRU 102 may receive positioning information from a base station (e.g., base station 114a, 114b) that adds or replaces GPS chipset 136 information through empty intermediaries 116, and/or from two or more base stations in the vicinity. Signal timing to determine its position. It should be appreciated that the WTRU 102 may obtain location information by any suitable positioning method while remaining consistent with the implementation.

The processor 118 can be further coupled to other peripheral devices 138, which can include one or more software and/or hardware modules that provide additional features, functionality, and/or wired or wireless connections. For example, peripheral device 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photo or video), a universal serial bus (USB) port, a vibrating device, a television transceiver, a hands-free headset, Bluetooth® Modules, FM radio units, digital music players, media players, video game player modules, Internet browsers, and more.

Systems, methods, and tools are disclosed for SIG design of OFDMA in WLAN systems. In an OFDMA WLAN, RUs can be efficiently allocated and signaled to support IoT/MTC. The RU allocation can be signaled in the HE SIG field. For example, the RU allocation can be signaled from the perspective of each RU. The RU allocation may be signaled at each STA, for example, to support distributed RU allocation, for example, when the RUs assigned to the STAs may be evenly distributed over the entire frequency band. The RU schedule information may be signaled, for example, at each STA, for example, to support continuous RU allocation. The RUs assigned to the STAs may be physically contiguous (e.g., contiguous). The RU allocation communication can be uniform over the entire bandwidth or in a frequency band greater than 20 MHz. The allowed RU allocation type can be limited, which reduces the complexity and overhead of messaging. The AP may announce the resource allocation in the resource allocation frame or announce it as part of the previous transmission, such as a PPDU in the A-MDPU or A-MSDU. The RU allocation message can support IoT. The minimum number of resources is available for IoT operations, such as the middle 26 tones. The SIG field can be carried within a symmetric RU allocation, for example, to reduce interference due to RF I/Q imbalance in OFDMA. In an OFDMA-based WLAN system, restrictions can be applied to RU allocation rules, for example, to limit the system to symmetric RU allocation. Dynamic encapsulation (eg, padding) and associated messaging can improve efficiency and reduce messaging overhead.

A wireless local area network (WLAN) can have multiple modes of operation, such as an Infrastructure Basic Service Set (BSS) mode and an Independent BSS (IBSS) mode. A WLAN in an infrastructure BSS mode may have an access point (AP) for a BSS. One or more stations (STAs) may be associated with the AP. The AP may have access and/or interfaces to a distribution system (DS) or other type of wired and/or wireless network that carries traffic outside of the BSS and outside the BSS. The traffic from the outside of the BSS to the STA can be reached through the AP, and the AP can transmit the traffic to the STA. Traffic originating from the STA and arriving at a destination outside the BSS can be sent to the AP, which can transmit the traffic to its respective destination. Traffic between STAs within the BSS can be sent by the AP, for example, from the source STA to the AP and from the AP to the destination STA. The traffic between STAs in the BSS can be peer-to-peer. Peer-to-peer traffic can be sent directly between the source STA and the destination STA, for example, by using 802.11e DLS or 802.11z Tunneled DLS (TDLS) Direct Connection Establishment (DLS). A WLAN in an Independent BSS (IBSS) mode may not have an AP, and STAs may directly communicate with each other. Communication in IBSS mode can be referred to as "ad-hoc" mode communication.

The AP can transmit beacons on fixed channels (eg, primary channels), for example, in the operation of the 802.11ac infrastructure mode. The channel can be, for example, 20 MHz wide. The channel can be the operating channel of the BSS. The STA can use the channel, for example, to establish a connection with the AP. The channel access mechanism in 802.11 systems is Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). The STA including the AP can listen to the primary channel, for example, in the CSMA/CA mode of operation. For example, when a channel is detected to be busy such that only one STA can transmit in a given BSS at that time, the STA may fall back.

High throughput (HT) STAs can communicate using, for example, a 40 MHz wide channel, as in 802.11n. The main 20 MHz channel can be combined with an adjacent 20 MHz channel to form a 40 MHz wide continuous channel.

Very high throughput (VHT) STAs support channels such as 20 MHz, 40 MHz, 80 MHz, and 160 MHz wide, as in 802.11ac. The 40 MHz and 80 MHz channels can be formed by, for example, combining successive 20 MHz channels. A 160 MHz channel can be formed by, for example, combining eight consecutive 20 MHz channels or by combining two non-contiguous 80 MHz channels, which can be referred to as an 80+80 configuration. The 80+80 configuration can be split into two stream segment parseres, for example, after channel encoding. For example, inverse fast Fourier transform and time domain processing can be performed separately for each stream. Streams can be mapped to two channels. Data can be transferred on both channels. The receiver can reverse the encoding process within the mechanism of the transmitter. The receiver can recombine the data transmitted on multiple channels. The recombined material can be sent to the Media Access Control (MAC).

Sub-GHz (eg, MHz) mode operation is supported, for example, by 802.11af and 802.11ah. The channel operation bandwidth and carrier can be reduced, for example, the associated bandwidth and carrier used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in, for example, the Television White Space (TVWS) spectrum. 802.11ah supports, for example, 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths in the non-TVWS spectrum. An example of an 802.11ah use case can be supported for use with a Meter Type Control (MTC) device in a macro coverage area. MTC devices can have limited capabilities (eg, limited bandwidth) and can be designed to have very long battery life.

WLAN systems (eg, 802.11n, 802.11ac, 802.11af, and 802.11ah systems) can support multiple channels and channel widths, such as channels designated as primary channels. The primary channel may, for example, have a bandwidth that is equal to the maximum common operating bandwidth supported by the STAs in the BSS. The bandwidth of the main channel can be limited by STAs that support the minimum bandwidth mode of operation. In the 802.11ah example, the primary channel can be 1 MHz wide, for example, when there are one or more STAs (eg, MTC type devices) that support 1 MHz mode, while the AP and other STAs support 2 MHz, 4 MHz, 8 MHz, 16 MHz or other channel bandwidth mode of operation. Carrier sense and NAV settings can depend on the state of the primary channel. For example, all available frequency bands may be considered busy and remain idle, although available, for example, when the primary channel is busy due to STAs supporting the 1 MHz mode of operation transmitting to the AP on the primary channel.

The available frequency bands can vary between different regions. For example, in the United States, the available frequency bands used by 802.11ah can range from 902 MHz to 928 MHz in the United States, 917.5 MHz to 923.5 MHz in Korea, and 916.5 MHz to 927.5 MHz in Japan. The total bandwidth available can vary from region to region. For example, depending on the country code, the total available bandwidth for 802.11ah can range from 6 MHz to 26 MHz.

For example, in time frames of the same symbol, such as during downlink OFDM symbols, spectral efficiency may be improved by downlink multi-user multiple input/multiple output (MU-MIMO) transmissions to multiple STAs. For example, downlink MU-MIMO can be implemented in 802.11ac and 802.11ah. When downlink MU-MIMO uses the same symbol timing to multiple STAs, interference to waveform transmissions of multiple STAs can be avoided. For example, when a STA involving a MU-MIMO transmission of an AP uses the same channel or frequency band, the operation bandwidth of the MU-MIMO transmission can be limited to the minimum channel bandwidth supported by the STA in the MU-MIMO transmission with the AP. .

IEEE 802.11TM High Efficiency WLAN (HEW), which can be referred to as High Efficiency (HE), enhances the quality of service experienced by wireless users in multiple usage scenarios, such as high-density deployment of APs and STAs in the 2.4 GHz and 5 GHz bands. (QoS). HE WLAN Radio Resource Management (RRM) technology supports a variety of applications or usage scenarios, such as data transfer for stadium events, such as high user density scenarios in train stations or corporate/retail environments, wireless services for video delivery and medical applications.

Short packets that can be generated by web applications can be applied to a variety of applications, such as virtual office, TPC acknowledgment (ACK), video streaming ACK, device/controller (eg, mouse, numeric keypad, game console), access (eg, probe request/response), network selection (eg, probe request, access network query protocol (ANQP)), and network management (eg, control frame).

MU features such as uplink (UL) and downlink (DL) orthogonal frequency division multiple access (OFDMA) and UL and DL MU-MIMO may be implemented in the WLAN. The DL acknowledgement sent in response to the UL MU transmission can be multiplexed.

OFDMA numerology for HEW is available. The OFDMA building blocks can be, for example, 20 MHz, 40 MHz, and 80 MHz.

Figure 2 is an example of an OFDMA numerology 200 for a 20 MHz component. For example, a 20 MHz OFDMA component can be defined as 26 tones with 2 pilots, 52 tones with 4 pilots, and 106 tones with 4 pilots. For example, there may be 7 DC nulls (DC NULL) and (6, 5) guard tones (eg, 6 guard tones on the left hand side and 5 guard tones on the right hand side), as shown in FIG. 2 . An OFDMA PPDU can carry a mix of different tone unit sizes within a boundary of 242 tone units.

Figure 3 is an example of an OFDMA numerology 300 for a 40 MHz component. For example, a 40 MHz OFDMA component can be defined as 26 tones with 2 pilots, 52 tones with 4 pilots, 106 tones with 4 pilots, and 242 tones with 8 pilots. For example, there may be 5 DC nulls and (12, 11) guard tones, as shown in Figure 3.

Figure 4 is an example of an OFDMA numerology 400 for an 80 MHz component. For example, an 80 MHz OFDMA component can be defined as 26 tones with 2 pilots, 52 tones with 4 pilots, 106 tones with 4 pilots, 242 tones with 8 pilots, and 16 guides. Frequency 484 sound. For example, there may be 7 DC nulls and (12, 11) guard tones, as shown in Figure 4.

One or more of the traditional Short Training Field (STF), Long Training Field (LTF), and Signal (SIG) fields may be provided. Efficient (HE) SIG-A and SIG-B designs are available.

The HE PLCP (Physical Layer Convergence Protocol) Protocol Data Unit (PPDU) may include legacy (L) preambles (eg, L-STF, L-LTF, and L-SIG) that may be replicated on each 20 MHz block, For example, for backward compatibility with conventional devices.

The HE-SIG-A field can be copied on each 20 MHz block, for example, after the traditional preamble to indicate common control information. For example, the HE-SIG-A field can be implemented using a 3.2 us discrete Fourier transform (DFT) period and a subcarrier with an interval of 312.5 kHz.

For example, the HE-SIG-B field can be implemented using a 3.2 us DFT period and a 312.5 KHz resource allocation carrier spacing in other technologies.

The MAC header may include a Receive Address (RA) and/or a Destination Address (DA). The RA in the MAC header may indicate the MAC address of the next immediate STA on the wireless medium receiving the frame in, for example, single user 802.11. The DA may indicate the MAC address of the final destination of the received frame.

The resource allocation information may be set in a physical layer (PHY) header (eg, VHT-SIG-A1) as, for example, a partial association identifier (AID) and a STA (a) from a 48-bit BSSID in 802.11ac. Multiple) 16-bit AID. The group ID can be signaled in the VHT SIG-A, for example, such that it can be used by the STA to determine if the MU PPDU means for it and which of the DL-MU-MIMO transmissions are to be demodulated . The assignment of the STA to the group can be managed by the group ID management frame.

Resource allocation in BSS using OFDMA can be more complicated than OFDM systems. For example, a BSS with a bandwidth of 80 MHz may have 37 RUs and may be assigned to multiple STAs simultaneously. A valid RU allocation message may indicate the assigned RU and/or associated STA, for example, to enable OFDMA operation in the WLAN system. The messaging scheme can be scalable between different system bandwidths, such as 20, 40, 80, 160 or 80 + 80 MHz.

Low-cost MTC and/or IoT type devices can be supported in HE WLANs. Low bandwidth MTC and/or IoT devices can use narrow bandwidth (eg, 5 MHz). RU allocation messaging and/or RU based feedback can enable efficient operation of low cost MTC and IoT devices.

RF I/Q imbalance in OFDMA can cause interference. In an OFDMA-based system, one or more frequency resources presented in the form of subchannels may be assigned to different wireless links that may be in the uplink direction or the downlink direction. Due to the RF I/Q amplitude and/or phase imbalance, the signal transmitted on the subchannel allocated on one side of the channel relative to the center frequency can cause interference to the other side of the channel as an image of the original signal.

Figure 5 is an exemplary power spectral density of a partially loaded OFDM signal with RF I/Q imbalance. Figure 5 depicts an example with 256 subcarriers in a 20 MHz channel. Subchannels with subcarriers 199 through 224 (shown as subchannel (SC) A) can load data. The RF I/Q imbalance can produce interference close to 23dBr in images with sub-carriers -199 to -224 sub-channels (shown as SC B).

In a single BSS scenario, for example, in OFDMA DL, the interference may not be significant, for example, since the transmit (Tx) power on all subchannels at each STA is the same as the Rx power on these subchannels. However, in OFDMA UL, for example when there is no power control or power control is inaccurate, the interference at the image sub-channel (eg, SC B) may be significant. STAs using subchannel B may be farther away from the AP than STAs using channel A.

Figure 6 is an example of the bit error rate (BER) performance of the interfered signal. Figure 6 shows an exemplary BER performance of a signal transmitted on sub-channel B, which suffers from interference due to transmissions on sub-channel A with I/Q imbalance. The line specified by dP can represent the power difference between sub-channels A and B. dP > 0 indicates that the signal power on SC B is lower than the signal power on SC A. As shown in Figure 6, for example, when power is not well controlled, significant performance penalty can occur.

For example, RU allocation in an uplink OFDMA scenario may result in and/or compensate for the effects of I/Q imbalance. The RU can be designed to distribute communications to, for example, prevent system damage due to I/Q imbalance.

The RU can be efficiently allocated and/or signaled in an OFDMA-based wireless local area network (WLAN) to support Internet of Things (IoT) and MTC (Machine Type Communication).

The HE WLAN or similar HE system can be implemented in a variety of ways (eg, technology, implementation). Technology can have multiple subsets (eg, variants) techniques. Techniques and/or subsets may be combined and/or modified.

The RU assignment can be signaled in the PLCH header. An example of RU allocation messaging in the HE SIG and/or legacy SIG may be provided.

In the first example, the RU allocation can be, for example, signaled from the perspective of each RU. Several RU allocation messaging techniques may be a variant of signaling RU assignments from each RU perspective.

The RU assignment can be signaled for a 20 MHz bandwidth system. Signaling the RU allocation for a 20 MHz bandwidth may include one or more of the following.

The STA ID in the resource allocation may be signaled or represented, for example, by AID/PAID or pre-assigned group ID and intra-group STA location. The group ID can be signaled, for example, in SIG-A (eg, IEEE 802.11ac SIG-A). SIG-A can be transmitted before HE SIG-A and/or HE SIG-B. The SIG-A can be signaled in the HE SIG-A and / or HE SIG-B preambles. The group ID field can have N bits. A group can include up to K STAs. The STA (e.g., each STA) may have a corresponding STA location in the group.

The RU allocation information can be signaled in the HE SIG-B or split between the HE SIG-A and the HE SIG-B. The RU allocation field can be used to carry the RU allocation information. The assigned STA ID may be signaled for each minimum size RU (eg, 26 tones in 802.11ax), for example, using the STA location or AID/PAID in the group. In some cases, not all RUs can be assigned. A predefined codeword (e.g., all 0s or all 1s) may be used to present an "unallocated" condition for RUs that are not assigned to any of the STAs in the BSS.

FIG. 7 is an exemplary format of the RU allocation field 702. The RU allocation field 702 can use the format shown in Figure 7, for example, when the assigned STAs may use different modulation and decoding schemes (MCS) and may have different numbers of spatial streams on each assigned RU. . Exemplary RU allocation field 702 can include STA ID 704, MCS 706, and/or N _StS 708.

Figure 8 is an exemplary format of the RU allocation field 802. The RU allocation field 802 can use the format shown in Figure 8, for example, when the assigned STAs can be restricted to use the same MCS and can have the same number of spatial streams on all assigned RUs within the BSS. The order of the assigned STA information fields may be determined based on previous fields assigned by one or more RUs (eg, implicit decisions). The exemplary RU allocation field 802 can include an MCS 804 and/or an N _StS 806.

The RU allocation can be signaled for bandwidths greater than 20 MHz. A bandwidth greater than 20 MHz can be represented by p times 20 MHz (eg, p x 20 MHz). 20 MHz RU allocation messaging can be extended, such as linearly. For bandwidths greater than 20 MHz, one or more variations can be used to extend 20 MHz RU allocation messaging. Such RU allocation messaging may include one or more of the following.

The STA ID in the resource allocation may be signaled or represented, for example, by AID/PAID or pre-assigned group ID and intra-group STA location. When group IDs are used, group management with bandwidths greater than 20 MHz OFDMA can be handled in a variety of ways. For example, a group can be used for all STAs allocated across the entire bandwidth. A single group ID can be signaled in SIG-A (eg, IEEE 802.11ac SIG-A), and SIG-A can be transmitted in one or more of the following ways: in HE SIG-A and HE SIG-B Previously, it was part of the preamble in HE SIG-A and/or in HE SIG-B. As another example, a group can be used for each of the 20 MHz bands in the entire bandwidth. There may be p group IDs signaled to the STA. The p group IDs may be sequentially signaled, for example, in HE SIG-A and/or HE SIG-B in the order of the associated 20 MHz bands. The first 20 MHz group ID is signaled first, followed by the second 20 MHz group ID, and so on. In one example, a respective group ID of 20 MHz bandwidth may be signaled in HE SIG-B, for example, when non-replicating HE SIG-B is transmitted on each 20 MHz band.

The RU allocation field for bandwidths greater than 20 MHz may be a linear extension of one or more 20 MHz bandwidth RU allocation field formats. STA ID subfield can be added The bits are signaled for the corresponding group ID of the p group IDs to be used for the entire bandwidth, for example, when one or more of the following conditions are true: the group ID and/or the STA in the group The location can be used to characterize the assigned STA ID; one common HE SIG-B can be used for the entire bandwidth or the common HE SIG-B can be replicated on each 20 MHz band; or p group IDs can be Used for the entire bandwidth (eg, for one group per 20 MHz band).

Numerical analysis of the 20, 40 and 80 MHz bands provides an estimate of the following communication overhead: for example, N bits for group ID index and group size (eg, 6 bits in 802.11ac) can allow up to 9 STAs. The 36-bit common RU allocation field may permit 4 bits to signal the location of STAs in a group of 9 RUs per 20 MHz band. The total overhead may be N + 36 bits for the 20 MHz band, N + (5 * 28) bits for 60 MHz, and N + (6 * 37 for 80 MHz) ) bit. The group ID management frame can contain 320 bits (eg, 2^N (group array) + 2^N*4 (position array) = 320 bits), 384 bits (eg, 2^N (group) Array) +2^N*5 (position array) = 384 bits) or 448 bits (eg, 2^N (group array) + 2^N*6 (position array) = 448 bits), for example, Support group, which allows up to 9 STAs.

The RU allocation may be signaled for downlink operation, for example, according to one or more of the following.

The AP may perform group management of two or more STAs capable of performing OFDMA-based transmission and reception using a group management frame, for example, when a group ID is used in the RU allocation communication STA ID.

The AP can monitor the conditions of the BSS (eg, the amount of downlink data buffered at the AP, power savings/sleep cycles, etc.). For example, when one or more conditions guarantee OFDMA transmission, the AP may determine to perform an OFDMA transmission. As an example, several STAs may have sufficient downlink data buffered at the AP such that the amount of data may allow for efficient OFDMA resource utilization.

The AP may select one or more STAs for DL transmission. For example, according to a suitable scheduling algorithm, the AP may select corresponding resource allocation and/or transmission parameters for one or more STAs, such as the assigned RU, MCS, MIMO parameters, the amount of data to be transmitted, and the like.

Accordingly, the AP can perform downlink OFDMA transmission. In an OFDMA transmission, the AP may set one or more RU allocation and/or DL transmission parameters in the PLCP header, for example, using the RU allocation communication described herein.

The STA may decode the detected PLCP header (eg, legacy SIG, HE SIG-A, HE SIG-B) and may interpret the received PLCP header, eg, according to the format specified in the RU allocation message described herein.

The STA may tune its receiver to the assigned RU(s) to receive and decode its downlink according to one or more parameters of the received SIG (eg, legacy SIG, HE SIG-A, and SIG-B). Road information.

Figure 9 is an example of tone planning and RU unit marking in the 20 MHz band. The STA may determine one or more tone plans (eg, including pilot and DC null values) based on the assigned RUs. As an example, the RU unit labeled "Unit 10" in Figure 9 may be assigned to the STA, for example, when the received RU allocation message indicates that RU units 1 and 2 are assigned to the STA.

For example, RU allocation messaging in the uplink may be provided in accordance with one or more of the following.

The AP may perform group management of the STA, and the STA can perform OFDMA-based transmission and reception using the group management frame, for example, when the group ID is used for the STA ID in the RU allocation communication.

The AP may monitor conditions of the BSS (eg, amount of uplink data buffered at the STA, power save/sleep period, path loss, or received power of a single STA at the AP). For example, when the condition guarantees transmission, the AP may determine to perform uplink OFDMA transmission. For example, several STAs may have sufficient uplink data, the amount of data may allow for efficient OFDMA resource utilization, at the AP, several STAs have similar received power, and the like.

The AP may select one or more STAs for UL transmission. For example, based on a suitable scheduling algorithm, the AP may select corresponding resource allocation and/or transmission parameters for the STA, such as the assigned RU, MCS, MIMO parameters, amount of data to be transmitted.

The AP may trigger a frame requesting transmission of UL MU PPDUs from the selected STA. The AP may set the RU allocation and DL transmission parameters in the trigger frame using the previously described RU allocation message.

The STA may interpret the RU allocation message in the received trigger frame, for example, according to the format specified in the previously described RU allocation message, for example, after receiving a valid trigger frame with the RU assignment for it. .

The STA may transmit the UL MU PPDU as an immediate response to the trigger frame according to the RU allocation and transmission parameters received in the trigger frame.

The STA may determine the tone plan (eg, including pilot and DC null values) based on the assigned RU. For example, the RU unit labeled as unit "10" in Fig. 9 may be assigned to the STA, for example, when the received RU allocation message indicates that RU units 1 and 2 are assigned to the STA.

The RU allocation may be signaled at each STA, for example, to support the distributed RU allocation, such as when the RUs assigned to the STAs are evenly distributed over the entire frequency band.

Figure 10 is an example of decentralized RU messaging with fixed STA information size. The RU communication field can be designed as shown in Figure 10. There may be N STA information fields 1010 (eg, STA information 1 to N). The 'k' (eg, 1 to N) STA information field may carry the RU schedule and other information for the kth STA. The STA information field may include one or more fields, such as STA ID field 1012, RU start location field 1014, RU interval field 1016, MCS field 1018, and/or N _sts field 1020.

The STA ID field 1012 can be used to carry STA identification. The STA ID may be, for example, a combination of a group ID and an STA location within a group. As an example, the STA ID may indicate an STA within a group of locations L, such as [Group M, Location L]. The STA ID in the messaging field may not be restricted to a special group. The STA ID may be, for example, a compressed version of an Association ID (AID) and a BSSID. The STA ID can be, for example, a compressed version of the AID. As an example, other types of BSSID or BSS identity may be signaled in the common SIG field.

The RU Start Location field 1014 can be used to indicate the location of the first RU assigned to the STA. For example, the location can be signaled using the RU index on the entire channel or using the band index and the RU offset on that band. In an embodiment of a total bandwidth of 80 MHz, two bits can be used to indicate four 20 MHz sub-bands and that k bits can be used to signal up to 2k RU offset locations, where each 20 MHz The subband can support up to 2k RUs.

The RU Interval field 1016 can be used to indicate the interval between the assigned RUs (eg, in RU).

The MCS field 1018 may indicate the MCS assigned to the STA. One MCS can be assigned to an RU (eg, all RUs) assigned to the STA.

The N _sts field 1020 may indicate the number of space-time streams assigned to the STA.

The RU schedule can be decentralized. Figure 11 is an example of a distributed RU schedule. In the example shown in Fig. 11, the RU under the dotted line can be assigned to the STA. The distance between these RUs can be indicated as an RU interval.

The RU allocation may be signaled for uplink and downlink operations, for example, according to the uplink and downlink RU allocations for uplink and downlink operations in the first example.

The RU message field can be inserted into the SIG-A field, the SIG-B field, or the SIG-A/SIG-B field. The RU message field inserted into the SIG-A/SIG-B field can be split into two parts, the first part of the SIG-A field and the second part of the SIG-B field.

The RU communication field can be carried in the control frame transmitted before the OFDMA transmission period. For example, the RU communication field can be carried in the trigger frame, and the trigger frame can be used to initialize the uplink OFDMA transmission.

RU schedule information can be signaled at each STA, for example, to support continuous RU allocation. The RUs assigned to the STAs may be physically contiguous.

Figure 12 is an example of a continuous RU message with a fixed STA information size. For example, the RU messaging field can be designed as shown in FIG. There may be N STA information fields 1210 (eg, STA information 1 to N). The 'k' (eg, 1 to N) STA information field 1210 may carry the RU schedule and other information for the kth STA. The STA information field 1210 may include one or more fields, such as a STA ID field 1212, an RU start location field 1214, an RU quantity field 1216, an MCS field 1218, or an N _sts field 1220.

The STA ID field 1212 can be used to carry the identification of the STA. The STA ID may be, for example, a combination of a group ID and an STA location within a group. As an example, the STA ID may indicate a STA in the group M with the location L, such as [Group M, Location L]. The STA ID in the messaging field may not be restricted to the special group. The STA ID may be, for example, a compressed version of an Association ID (AID) and a BSSID. The STA ID can be, for example, a compressed version of the AID. As an example, other types of BSSID or BSS identity may be signaled in the common SIG field.

The RU Start Location field 1214 can be used to indicate the location of the first RU assigned to the STA. For example, the location of the first RU assigned to the STA can be signaled using the RU index on the entire channel. The location of the first RU assigned to the STA can be signaled using the band index and the RU offset on that band. In the example for a total bandwidth of 80 MHz, two bits can be used to indicate four 20 MHz sub-bands and up to 2k RU offset locations can be signaled using k-bits, where each 20 MHz sub-segment The belt can support up to 2k RUs.

The RU Quantity field 1216 can be used to indicate the number of consecutive RUs assigned to the STA.

The MCS field 1218 may indicate the MCS assigned to the STA. The MCS can be assigned to one or more (eg, all) RUs assigned to the STA.

The N _sts field 1220 may indicate the number of spatial streams assigned to the STA.

Figure 13 is an example of a continuous RU schedule. Two or more RUs can be allocated continuously.

Figure 14 is an example of a contiguous RU allocation with multiple RU sets. A STA may be assigned multiple RU sets. The RU set can be considered to be continuously allocated.

Figures 15A and 15B are examples of continuous RU messaging field designs with variable STA information sizes. For example, when the number of RU sets assigned to a STA is variable, the STA information field 1510 may have different sizes. For example, the number of RU sets assigned to the STA may be signaled in another messaging field, which may be transmitted before the RU communication field. In another example, a STA delimiter may be added in each STA information field to cause the STA to detect the delimiter and the beginning of the STA information field. The STA delimiter may be a predetermined sequence or a transmitter-receiver (e.g., ad hoc). CRC protection can be applied to STA delimiters.

Figure 15A shows the design of a messaging field with each STA MCS assignment. For example, the RU communication field can be designed as shown in FIG. 15A or FIG. 15B. There may be N STA information fields (eg, STA information 1 to N). The 'k' (eg, 1 to N) STA information field may carry the RU schedule and other information for the kth STA. The STA information field may include one or more of the following: STA Separation Symbol Field 1512, STA ID Field 1514, One or more RU Set Fields 1520, MCS Field 1522, or N _sts Field 1524.

The STA Separation Symbol field 1512 is available. The STA Separation Symbol field 1512 may be optional, for example, when the size of each STA information field 1510 is signaled in the SIG field prior to the RU communication field.

The STA ID field 1514 can be used to carry STA identification. The STA ID may be, for example, a combination of a group ID and an STA location within a group. As an example, the STA ID may indicate a STA in the group M with the location L, such as [Group M, Location L]. The STA ID in the messaging field may not be restricted to the special group. The STA ID may be, for example, a compressed version of an Association ID (AID) and a BSSID. The STA ID can be, for example, a compressed version of the AID. As an example, other types of BSSID or BSS identity may be signaled in the common SIG field.

The RU set field 1520 (eg, RU set 1 to RU set k) can be used to indicate a continuous RU set allocation. The RU set field 1520 may include an RU start location field 1526 and/or an RU quantity field 1528. The RU Start Location field 1526 can be used to indicate the location of the first RU assigned to the STA. The RU Quantity field 1528 can be used to indicate the number of consecutive RUs assigned to the STA.

The MCS field 1522 may indicate the MCS assigned to the STA. The MCS can be assigned to one or more (eg, all) RUs assigned to the STA.

The N _sts field 1524 may indicate the number of space time streams assigned to the STA.

Figure 15B shows the communication field design for each RU set MCS assignment. For example, one or more of the RU set information fields 1520 can include an MCS field 1532 and/or an N _sts field 1534.

The RU allocation may be signaled for uplink and downlink operations, for example, according to the uplink and downlink RU allocations described herein for uplink and/or downlink operation.

The RU message field can be inserted into the SIG-A field, the SIG-B field, or the SIG-A/SIG-B field. The RU message field inserted into the SIG-A/SIG-B field can be divided into two parts, the first part of the SIG-A field and the second part of the SIG-B field.

The RU communication field can be carried in the control frame transmitted before the OFDMA transmission. For example, the RU message frame field can be carried in the trigger frame. The trigger frame can be used to initialize an uplink OFDMA transmission.

The RU allocation may include flat RU allocation messaging for bandwidths greater than 20 MHz, such as 40 MHz, 80 MHz, and/or 160 (or 80 + 80) MHz. Flat RU allocation across the entire bandwidth or a band greater than 20 MHz (eg, 160 (80+80) MHz) compared to the first example containing 20 MHz based hierarchical RU allocation for bandwidths greater than 20 MHz Can be used to signal the RU allocation.

Figure 16 is an example of flattening RU allocation messaging.

The STA ID in the resource allocation can be signaled or represented, for example, by AID/PAID. The STA ID in the resource allocation or the pre-assigned group ID and the STA location in the group. For example, when a group ID is used with a flat RU allocation that spans the entire bandwidth greater than 20 MHz, one group can be used for one or more (eg, all) STAs allocated throughout the bandwidth. In the preamble, the group ID (eg, IEEE 802.11ac group ID) can be signaled before HE SIG-A and HE SIG-B. The group ID field may have N bits, each group may contain up to K STAs and each STA may have a corresponding STA location in the group. For example, the 802.11ac group ID field that reuses N=6 bits and K=4, 5, and 6 bits can support up to 9, 18, and 37 in groups of 20 MHz, 40 MHz, and 80 MHz, respectively. STA.

The RU allocation information can be signaled. The RU allocation information can be signaled in HE SIG-A, HE SIG-B or split between HE SIG-A and HE SIG-B. The RU schedule information can be signaled at each STA by one or any combination of the following three examples and/or other implementations.

A one-dimensional (1D) minimum RU M-dot map (1D min_RU bitmap) can be used to signal the RU allocation for each STA, where M can represent the minimum for a given bandwidth (or band) The total number of RUs in size. As an example, 9-dot, 18-dot, and 37-dot can be used to signal each STA for 20 MHz, 40 MHz, and 80 MHz (or 160 (80+80) MHz), respectively. Send the RU assignment. The bits in the bitmap may be binary (eg, 1 or 0), for example, to indicate whether the corresponding minimum size (minimized) RU is assigned to the STA. For example, 1 may indicate that the minimized RU is assigned to the STA, and 0 may indicate that the STA is not allocated. The 37-map can be used to signal the RU assignment for 80 MHz. For example, the 1st and 37th bits in the bitmap may be equal to 1 to indicate that the first and last (eg, 37th) 26-tone RUs are assigned to the STA.

The RU size associated with the bitmap RU assignment may be signaled (e.g., explicitly signaled) to the STA for demodulation and decoding. For example, a three-bit (3 bit) RU size indication (eg, a RU size indication) may indicate six different RU sizes, such as 26 tone RU, 52 tone RU, 106 tone RU, 242 tone RU, 484 tone RU, and 996 tone. RU. The mapping between the 6 RU sizes and the 3-bit size indications may be predefined or in any format. A number (eg, T) of 3-bit RU size indications may be signaled, eg, based on the total number of RUs assigned to the STA (eg, T). T 3-bit RU size indications may be signaled after, for example, a 1D min_RU bitmap.

The RU size associated with the bitmap RU assignment may be signaled (e.g., implicitly signaled) to the STA for demodulation and decoding, for example, when a single "1" bit may be predefined or assumed to indicate that the RU allocation is greater than The minimum size RU (eg, 26 tone RU size). In the example where the 37-dot pattern is used to signal the RU allocation for 80 MHz, the first and second bits of the bitmap are equal to one. The first 52-tone RU is available for signal transmission to the STA. Implicit messaging of different RU sizes can be used to allocate different sized RUs across the entire frequency band.

In the example where the 37 dot pattern is used to signal the RU allocation for 80 MHz, for example, as shown in FIG. 16, the 1, 2, 3, 4, and 5 bits of the bitmap are equal to 1 available signal indication. Two 52-tone RUs or one 106-tone RU plus one 26-tone RU (5th bit) are assigned to the STA. In one example, only the 5th 26-tone can be assigned, for example, since the 52-tone and the 106-tone RU cannot be assigned to the 5th 26-tone position as indicated in the example shown in FIG.

L bits can be used to signal a configurable RU allocation across the entire bandwidth (eg, frequency band). L may be subject to a total number of configurable RU allocations across the entire bandwidth (or frequency band), eg, 2 ^L >= total number of configurable RU allocations across the entire bandwidth (or frequency band). For the examples of 20 MHz, 40 MHz, and 80 MHz, there may be, for example, 16, 33, and 68 configurable RU allocations, where L equals 4, 6, and 7 bits may be used to signal the configurable RU to the STA, respectively. distribution. The mapping between configurable RU locations and L-bit indications can be predefined and/or specified in any format. The L bits can signal which configurable RU is assigned to the STA, for example, when each STA is assigned an RU. The total number of RUs assigned to the STA (eg, T RUs) may be signaled, for example, when more than one RU can be assigned to the STA. The L-bit index assigned by the T RUs can follow the RU allocation communication.

A two-dimensional (2-D) RU bitmap can signal the location of the RU allocation across the entire bandwidth (or band). The first dimension of the 2D RU bitmap can signal the RU size, which can correspond to the columns of RU components, as shown in FIG. Columns 1, 2, 3, 4, 5, and 6 may indicate 26 tone RU, 52 tone RU, 106 tone RU, 242 tone RU, 484 tone RU, and 996 tone RU, respectively. The second dimension of the 2D RU bitmap can signal the index of the RU for a given column or RU size assigned to the desired STA. The size of the different 1D bitmaps can be used for different RU sizes. For example, the 2D size can be [1, 37], [2, 16], [3, 8], [4, 4], [5, 2], and/or [6, 1]. For example, one or more 1D RU bitmaps may be signaled for the RU allocation of the STA based on the bandwidth. As an example, 4, 5, and 6 2D RU bitmaps may be signaled, for example, for 20 MHz, 40 MHz, and 80 MHz, respectively.

The RU messaging field can be used to carry one or more of the following RU allocation information.

The STA information k field may carry the RU schedule and/or other information for the kth STA. The STA information field may include, for example, one or more of a STA delimiter, a STA ID, and/or one or more RU allocation fields.

A STA delimiter may be added to each STA information field, for example, to permit the STA to detect the beginning of the delimiter and/or STA information field. The STA delimiter may be a specified sequence or a transmitter-receiver (eg, ad hoc). CRC protection can be applied to STA delimiters. For example, when the number of RUs assigned to a STA may be different, the STA Separation Symbol fields may have different sizes. The STA Separation Symbol field may be optional, for example, when the size of the STA information field can be signaled in the SIG field before the RU communication field.

The STA ID field can be used to carry STA identification information. The STA ID information may include, for example, an AID/PAID or a pre-assigned group ID and a STA location in the group.

One or more RU allocation fields may be used to indicate one or more RUs assigned to the STA. The RU field may include one or more of the following subfields, for example, depending on the RU allocation implementation.

Figures 17A and 17B are examples of flattening RU communications. The 1D min_RU bitmap field 1716 can be used to signal the RU allocation for each STA. The 1D min_RU bitmap may be, for example, 9-dot, 18-dot, and 37-dot for 20 MHz, 40 MHz, and 80 MHz (or 160 (80+80) MHz, respectively). The bits in the bitmap may be binary (eg, 1 or 0) to indicate whether the corresponding minimum size RU is assigned to the STA.

The RU size indication field 1720 may be, for example, 3 bits to indicate one of 6 different RU sizes, 6 different RU sizes such as 26 tone RU, 52 tone RU, 106 tone RU, 242 tone RU, 484 tone RU, and 996 tone RU.

Figure 17A shows an example of RU messaging with one (e.g., common) MCS field 1722 and _Nsts field 1724 for each RU assigned to the STA. For example, each STA information field 1710 may include one MCS field 1722 and one N _sts field 1724 for the STA. Figure 17B shows an example of RU messaging with each RU MCS and Nsts assignment, where different RUs with different RU sizes may carry their own MCS and Nsts. Each STA information field 1710 can include a plurality of MCS fields 1722 and/or a plurality of Nsts fields 1724. For example, each STA information field 1710 can include a plurality of RU size indication fields 1720. Each of the plurality of RU size indication fields 1720 can include an MCS field 1722 and/or an Nsts field 1724.

Figures 18A and 18B are examples of flattening RU messaging. Each STA information field 1810 may include a total number of RU fields 1816 and/or an index of one or more RU fields 1820. The total number of RU fields 1816 may indicate the number of RUs assigned to the STA. The index of one or more RU fields 1820 may indicate the index of the RU using the length of the L bits. For example, L=4, 6, and 7 bits can represent 16, 33, and 68 RU allocations for 20 MHz, 40 MHz, and 80 MHz, respectively.

Figure 18A shows an example of RU messaging with one (e.g., common) MCS field 1822 and Nsts field 1824 for all RUs assigned to the STA. For example, each STA information field 1810 may include one MCS field 1822 and one N _sts field 1824 for the STA. Figure 18B shows an example of RU messaging with each RU MCS and Nsts assignment, where different RUs with different RU sizes may carry their own MCS and Nsts. Each STA information field 1810 can include a plurality of MCS fields 1822 and/or a plurality of N _sts fields 1824. For example, each STA information field 1810 can include a field 1820 of multiple RU indexes. Each of the plurality of RU index fields 1820 can include an MCS field 1822 and/or an N _sts field 1824.

Figures 19A and 19B are examples of flattening RU communication. Each STA information field 1910 may include a plurality of 2D RU bitmap fields 1920. The 2D RU bitmap field 1920 may be signaled to have different sizes (eg, [1, 37], depending on the video width). Six 2D RU dot patterns of [2, 16], [3, 8], [4, 4], [5, 2], and [6, 1], for example, to indicate the RU allocation of the STA.

Figure 19A shows an example of RU messaging with one (e.g., common) MCS field 1922 and _Nsts field 1924 for each RU assigned to the STA. For example, each STA information field 1910 may include one MCS field 1922 and one Nsts field 1924 for the STA. Figure 19B shows an example of RU messaging with each RU MCS and Nsts assignment, where different RUs with different RU sizes may carry their own MCS and Nsts. Each STA information field 1910 may include a plurality of MCS fields 1922 and/or a plurality of N _sts fields 1924. For example, each STA information field 1910 can include a plurality of 2D RU bitmap fields 1920. Each of the plurality of 2D RU bitmap fields 1920 may include an MCS field 1922 and/or an N _sts field 1924.

The MCS field 1922 may indicate the MCS assigned to the STA. The same or different MCS can be assigned to all RUs assigned to the STA.

The N _sts field 1924 may indicate the number of space-time streams assigned to the STA. The number of space-time streams may be the same or different for each RU assigned to the STA.

Flattening RU allocation messaging can support flexible scheduling, such as supporting any continuous or non-contiguous RU allocation to any STA on any bandwidth (or band), including when not all RUs for the entire bandwidth (or band) distribution. Flattening assignments can be applied to any bandwidth, such as greater than, less than, or equal to 20 MHz.

The RU allocation may be signaled for uplink and downlink operations, for example, according to the uplink and downlink RU allocations described herein for uplink and downlink operations.

One or more RU allocation patterns can be limited, which can reduce communication complexity and/or overhead. For example, in a 20 MHz bandwidth, the RU allocation pattern can be limited (eg, limited to the RU allocation pattern as shown in FIG. 20).

Figure 20 is an example of a limited RU allocation for the 20 MHz band. Larger bandwidths, such as continuous bandwidths greater than 40 MHz, such as 60 and 80 MHz, may include additional 26-tone RUs associated with the exemplary RU allocation pattern shown in FIG.

Type 1 messaging can be revealed. The RU allocation can be signaled at each STA. In an example, each STA may be assigned a unit (eg, 1 to 16) in a 20 MHz bandwidth. The STA ID and RU unit index may be sent to assign resources to the STA.

The STA ID in the resource allocation can be signaled or represented by AID/PAID. The STA ID in the resource allocation may be signaled or represented by a pre-assigned group ID and a STA location in the group. The group ID can be signaled in a legacy 802.11ac SIG-A (eg, it can be transmitted before HE SIG-A and/or HE SIG-B), in an HE SIG-A preamble, or in a HE SIG-B preamble . The group ID field can have N bits. A group can include up to K STAs. The STA may have a corresponding STA location in the group.

The RU allocation information can be signaled. The RU allocation information can be signaled in the HE SIG-B. The RU allocation information can be split between HE SIG-A and HE SIG-B. The RU allocation field can be used to carry RU allocation information, for example, a RU unit index (eg, 1 to 16 can be indicated by 4 bits).

The communication overhead can be calculated, such as the number of assigned STAs* (STA ID + 4). In the example, the maximum overhead can be 9 * (STA ID + 4).

Figure 21 is an example of type 1 messaging that explicitly signals the number of STAs.

Figure 22 is an example of type 1 messaging that explicitly signals the number of STAs.

In an example, the number of STAs in the allocation can be signaled and the STA ID and RU allocation fields can be signaled, for example, after the number of STAs. In an example, a separator, such as [0000], may be placed after the STA ID, for example, to indicate the total number of STAs allocated.

Type 2 messaging can be revealed. A bitmap (e.g., 16 bits) of the assigned RU unit can be sent, for example, to indicate the allocated resources. The number of STAs in the allocation can be implicitly signaled. The STA IDs may, for example, be sent in the order of positive bitmaps. In an example, separate bitmaps may be sent to each of the plurality of STAs to indicate the allocated resources. In an example, a single bitmap may be sent to multiple (eg, all) STAs to indicate a particular assignment. When a single bitmap is sent to indicate the allocation of multiple STAs, the STA ID is implicitly mapped to the allocated resources. A single STA can have multiple assignments. The STA ID in the resource allocation can be signaled or represented by AID/PAID. The STA ID in the resource allocation may be signaled or represented by a pre-assigned group ID and a STA location in the group. The RU allocation information can be signaled in the HE SIG-B. The RU allocation information can be split between HE SIG-A and HE SIG-. The RU allocation field can be used to carry RU allocation information, such as, for example, a RU unit index.

The communication overhead can be calculated, for example, the number of assigned STAs *STA ID + 16. In one example, the maximum overhead can be 9 *STA ID + 16.

Figure 23 is an example of type 2 messaging that implicitly signals the number of STAs.

Figure 24 is an example of type 2 messaging that implicitly signals the number of STAs.

Figure 25 is an example of type 2 messaging that implicitly signals the number of STAs.

In an exemplary scenario, [1, 2, 5, 11, 15] can be assigned and the STA ID can be 6 bits. Type 1 messaging can include 50 bits, while Type 2 messaging can include 46 bits.

For example, when the AP and STA agree on the minimum allowed allowed bandwidth and/or the allowed allowed bandwidth (eg, only one bandwidth), the overhead can be reduced. The 26 RU channel between the DC or 20 MHz band (such as channel 5) can be assigned (eg, always).

Figure 26 is an example of the minimum allowable bandwidth. In one example, three-bit messaging may be provided with a minimum allowed bandwidth of 52 tones and an allocation based on RUs with indices of [5, 10, 11, 12, 13, 14, 15, 16].

Figure 27 is an example of a limited number of allowed bandwidths. In one example, 2-bit messaging is provided when the only allowed bandwidth is 104 and the allocation is based on [5, 14, 15].

The resulting bitmap can be used with the Type 1 and Type 2 RA packets discussed above.

The RU allocation may be signaled for uplink and downlink operations, for example, according to the uplink and downlink RU allocations described herein for uplink and downlink operations.

The AP can announce the resource allocation in the resource allocation frame. The AP may announce the resource allocation as part of the previous transmission, for example, a PPDU or an A-MDPU in the A-MSDU. The allocated resources can be associated with an index. The preamble, such as the SIG-A or SIG-B of the resource, can contain an index. The index may indicate the resources allocated to the STA.

Figure 28 is an example of a resource allocation frame format.

The resource allocation frame can include one or more of a PLCP header 2802, a MAC header 2804, one or more session information fields 2806, or an FCS field 2808.

The PLCP header 2802 may include information indicating that the frame is a resource allocation frame.

The MAC header 2804 may contain information (e.g., type or subtype) indicating that the frame is a resource allocation frame.

Session information field 2806 may include information about one or more sessions (eg, from session 1 to session N). The resource allocation frame can include a plurality of session information fields 2806. E.g. Each session may have a corresponding session information field 2806. The session information field may include one or more of the following information items regarding the session during which the AP or one or more STAs may transmit UL and/or DL traffic. One or more of the applicable session number fields 2810 can identify sessions within a certain time period, such as within a plurality of time units within the same TXOP, such as microseconds (ms).

Timing offset field 2812 identifies the offset at which the session begins. The offset can be defined from the transmission of the current frame or a reference to a time.

Session type field 2814 may be, for example, UL, DL, UL/DL, random access, content based, or a combination of the above.

The duration field 2816 can specify an approximate duration of the session.

The group ID field 2818 can identify a group of STAs involved in the session.

The assigned amount field 2820 can be included in the session information field 2806. The Allocation Amount field 2820 can indicate how many allocations are provided to the session.

One or more allocation fields 2822 may be included in the session information field 2806. Each of the one or more allocation fields 2822 may include information assigned to one or more STAs, such as index field 2824, STA information field 2826, and/or resource field 2828. One or more of the following may apply. Index field 2824 can be used to identify one or more resources assigned to one or more STAs. The STA information field 2826 may identify one or more STAs, for example, by STA MAC address, AID, and/or other identifiers. Resource field 2828 may indicate one or more resources assigned to one or more STAs identified in STA information field 2826. For example, one or more resources may be identified by a bitmap. The "1" indicated in the bitmap may be associated with a resource block (RB) assigned to one or more STAs. The size of the bitmap can be specified by the bandwidth. Resource field 2828 may include an indication of the RB size. Resources can be identified by the number associated with the RB.

The collection or subset of portions of the resource allocation frame can be implemented as part of an information element, an activity frame, an NDP frame, control, management, data or extension frame, MAC or PLCP header, and the like.

The AP may announce resource allocations for one or more sessions (eg, upcoming upcoming sessions in the near future), for example, using resource allocation frames as part of other frames, as part of the TXOP, as an A-MPDU. Part of it, as part of the M-DSDU frame and/or as part of the trigger frame. The resource allocation can be associated with one or more of a session number, a group ID, or an index.

Figure 29 is an example of a resource allocation frame announced parameter to indicate resource allocation in a future session. Figure 29 illustrates an example of how the parameters announced in the resource allocation frame are included in the transmission of future sessions.

The session number may, for example, be included in a common portion of one or more transmissions in the session, such as in the SIG-A of the UL and/or DL transmission of the STA.

The group ID may for example comprise a common part of one or more transmissions in the session, for example in the SIG-A of the UL and/or DL transmission of the STA allocated in the session, for example when the group of STAs has been assigned All the resources of the special channel. The group ID may be included in SIG-B (eg, in SIG-B associated with the RB assigned to the STA group), for example, when a group of STAs has been assigned to a portion of the channel.

The index may, for example, be included in a portion of one or more transmissions in the session, for example, in SIG-B associated with an RB assigned to one or more STAs identified in the resource allocation frame.

The AP may not include an additional indication in the DL transmission in the preamble for resource allocation. For example, when the AP has announced resource allocation using the resource allocation frame, the AP may not include an additional indication in the DL transmission preamble.

The STA can wake up at the time determined by the time offset. The time offset may be associated with a session in which the STA has been assigned a resource, for example, when the STA has received a resource allocation frame. When in a awake state, such as by receiving a DL transmission from an AP, the STA may search for an appropriate group ID and/or an index in the preamble (eg, SIG-A and SIG-B), for example, to find a suitable assignment to Your own resources. The index and/or group ID can identify more than one STA. The identified STA may decode the remainder of the transmission, such as a MAC header, for example, to identify whether the resource is allocated to itself or whether the resource is allocated as a group transmission.

The AP may include one or more of a session number, a group ID, or an index in the UL case in the trigger frame. The STA may receive the trigger frame and the STA may search for resources allocated to the STA in the UL session. The STA may transmit one or more UL transmissions to the AP according to the identified resources. The STA may include resource allocation information, such as SIG-A and/or SIG-B portions or other portions of the preamble. The resource allocation information may include one or more of a session number, a group ID, or an index in the uplink transmission.

IRU allocation messaging can support IoT. Low cost MTCs can be enabled, for example, by efficient techniques and/or low cost of resource allocation and/or scheduling by MTC type devices. For example, an IoT device may not require a large amount of resources and/or bandwidth for IoT operations. A minimum amount of resources can be used for IoT operations. For example, an IoT operation can use the middle 26 tones.

Figure 30 is an example of narrow band allocation for IoT operation.

In the example, the radio can support operation on the 2.5 MHz spectrum for data manipulation. For example, backward compatibility is enabled by transmitting a preamble on the 20 MHz bandwidth and signaling the field. The HE PPDU may not include legacy preambles (eg, L-STF, L-LTF, and L-SIG), for example, in narrowband (<20 MHz) uplink transmissions using UL-OFDMA, such as the presented IoT example .

SIG-B can be used to indicate narrowband operation, such as for UL-OFD MA. One or more of the following may be indicated for narrowband data transmission, control power, transmission power, control of the number of transmitted pilots, control of the location of the transmitted pilot, indication to other STAs that narrowband operation is in progress Or an indication of the MCS that can be supported.

The SIG can have a symmetric RU allocation. Symmetric RU allocation may, for example, reduce interference caused by RF I/Q imbalance in OFDMA. One or more restrictions may be applied to RU allocation rules in an OFDMA-based WLAN system. For example, the system can be limited to symmetric RU allocation.

Figure 31 is an example of symmetric RU allocation. For example, as shown in FIG. 31, the first RU (e.g., RU1) can be paired with the last RU (e.g., RU9) to form a symmetry. A symmetric RU pair 1 (eg, SRU1) may indicate a symmetric pairing of RU1 and RU9, eg, SRU1=[RU1, RU9]. Similarly, SRU2 may indicate symmetric pairing of RU2 and RU8 (eg, [RU2, RU8]), SRU3 may indicate symmetric pairing of RU3 and RU7 (eg, [RU3, RU7]), and SRU4 may indicate symmetry of RU4 and RU6 Pairing (eg, [RU4, RU6]).

A public messaging field (eg, HE-SIG-A or HE-SIG-B field) may use one or more bits to indicate a symmetric RU allocation. SRU indexes (eg, alternatives to RU indexes) can be used, for example, to distribute the messaging portion in a detailed RU to reduce messaging overhead.

The RU allocation communication field can be carried in the control frame, such as the trigger frame, before the OFDM transmission. Symmetric RU allocations can be signaled in the control frame prior to OFDM transmission. One or more SRU indexes can be used for RU allocation messaging.

Paired RUs can be assigned to the same STA. The RU information on the SRU can represent the RU information on the two paired RUs. The disclosed techniques can be applied to or applied with symmetric RU allocation techniques, for example, by using SRU indexes instead of RU indexes. Symmetric RU assignments mitigate the effects of RF I/Q imbalance.

Dynamic packaging and associated messaging are available. Dynamic packaging improves efficiency and/or reduces messaging overhead.

Multiple OFDM symbols can be sent via the MAC PDU. Each of the plurality of OFDM symbols can be associated with a first length and/or a first duration of the material. The first duration may be associated with the number of modulation symbols assigned to the STA within the OFDM symbols of the plurality of OFDM symbols. The first length of the data may be associated with the length of the material (eg, the maximum length), which may be carried by the STA in each of the plurality of OFDM symbols. The data can be mapped to multiple OFDM symbols.

The system can support one or more last OFDM symbol formats. The final OFDM symbol format may be based, for example, on the size of the modulated data symbols left for the last OFDM symbol and/or the length of the data transmitted in the last OFDM symbol (eg, the second length of the material).

In a first format (eg, Format 1), the last OFDM symbol of the plurality of OFDM symbols may have a duration of 3.2 us in addition to the GI, eg, when the size of the modulated symbol is and/or for the last OFDM The second length of the symbol's material is equal to or less than 1⁄4 of the first length of the material.

In a second format (eg, Format 2), the last one of the plurality of OFDM symbols may have a duration of 6.4 us in addition to the GI, eg, when the size of the modulated symbol is and/or for the last OFDM The second length of the symbol's material is equal to or less than 1⁄2 of the first length of the material but greater than 1⁄4 of the first length of the material.

In a third format (eg, Format 3), the last OFDM symbol of the plurality of OFDM symbols may have a duration of 9.6 us in addition to the GI, eg, when the size of the modulated symbol is and/or for the last OFDM The second length of the symbol's material is equal to or less than 3⁄4 of the first length of the material but greater than 1⁄2 of the first length of the material.

In a fourth format (eg, Format 4), the last OFDM symbol of the plurality of OFDM symbols may have a duration of 12.8 us in addition to the GI, eg, when the size of the modulated symbol is and/or for the last OFDM The second length of the symbol's data is greater than 3⁄4 of the first length of the data.

The first length of the data may be the number of modulated symbols assigned to the STA by one OFDM symbol. When considering GI, the duration of the last symbol can be [3.2, 6.4, 9.6, 12.8] + GI us, where GI can be 0.8 us, 1.6 us, or 3.2 us.

The second length of the data can be determined, for example, the length of the data transmitted in the last OFDM symbol. For example, it may be determined that the second length of the material transmitted in the last OFDM symbol is less than the first length of the material. The last OFDM symbol can be associated with a transmission duration, such as a first duration. For example, the transmitter can measure the length of the data transmitted in the last symbol. The length of the data (eg, the second length) transmitted in the last OFDM symbol may be compared to the length of the available data carrier (eg, the first length) in the last OFDM. The second length can be determined to be less than the first length. The last OFDM symbol can be modified based on the second length (eg, using a ratio of the second length to the first length). For example, the last OFDM symbol can be modified to be 1⁄4, 1⁄2 or 3⁄4 of the first duration depending on the second length. For example, when the second length of the material in the last OFDM symbol is less than or equal to 1⁄4 of the first length of the material, the last OFDM symbol can be modified to 1⁄4 of the first duration. In another example, when the second length of the material is less than or equal to 1⁄2 of the first length of the material but greater than 1⁄4 of the first length of the material, the last OFDM symbol can be modified to 1⁄2 of the first duration. In another example, when the second length of the material is less than or equal to 3⁄4 of the first length of the material but greater than 1⁄2 of the first length of the material, the last OFDM symbol can be modified to 3⁄4 of the first duration. In another example, when the second length of the material is greater than 3⁄4 of the first length of the material, the last OFDM symbol may not be modified. The second duration of the last OFDM symbol can be indicated via a PHY header or a MAC header. In another example, the ratio of the second length of the material to the first length of the material may be indicated via a PHY header or a MAC header.

The subcarrier mapping can be changed to enable the generation of periodic symbols and one period of periodic symbols can be transmitted, for example, when the amount of data is less than the length of the symbol (eg, using 802.11 if a 20 MHz channel is assigned to the STA) 1⁄4 or 1⁄2 of the 64 symbols or 128 symbols of ax numerology. A periodic symbol can be generated based on the second length of the last OFDM symbol.

The receiver can determine the length of the last OFDM symbol by a variety of methods. As an example, the length of the last OFDM symbol can be signaled in the PHY or MAC header. For example, the receiver can estimate (e.g., in a blind manner) the length of the last OFDM symbol, e.g., based on different lengths of the last OFDM symbol (e.g., four), such as 1⁄4, 1⁄2, 3⁄4, and 1 OFDM symbols. For example, the length field in the L-SIG can be re-interpreted to indicate a segment of the OFDM symbol. For example, the length field defined in the L-SIG can be calculated using an OFDM symbol duration of 4 us. 802.11ax supports two basic symbol durations, such as 3.2 us+GI and 12.8 us+GI. As indicated in Equation 1, four (4) us can be considered as 3.2 us symbol duration plus 0.8 us GI: Equation 1 where TXTime can be the total transmission duration of the packet of us. When the 1⁄4 or 1⁄2 OFDM symbol duration is used for the last symbol, TX_Time can be calculated based on the 1⁄4 or 1⁄2 OFDM symbol duration. The T_Lpreamble can be the duration of a microsecond traditional preamble (eg, including L-STF, L-LTF, and L-SIG). The ratio can be a bit of each encoded symbol signaled in the L-SIG field. Nsym can be the number of decoded symbols carried by an OFDM system used in legacy mode, such as 48 decoded symbols.

The transmitter can map the data to multiple OFDM symbols in the frame. The transmitter can measure the number of remaining data symbols to be mapped to the last OFDM symbol.

Figure 32 is an example of dynamic padding in each of the fourth subcarriers (1/4 data). The plurality of OFDM symbols can have a first duration. A plurality of OFDM symbols can be associated with a first length of material. For example, each of the plurality of OFDM symbols can transmit a first length of the material. The data may be placed in each of the fourth carriers, for example, when the data length (e.g., the second length) is less than or equal to 1⁄4 of the length of the last OFDM symbol 3102. For example, the second length of the material may be determined to be less than the first length of the material for the last OFDM symbol 3102. When the IFFT of the last OFDM symbol is performed, the generated time domain symbol may be a periodicity having four periods. The last three cycles can be removed and the modified last OFDM symbol 3104 can be sent. The modified last OFDM symbol 3104 may be 1⁄4 of the last OFDM symbol. For example, the last OFDM symbol 3102 can be modified (eg, reduced) to the modified last OFDM symbol 3104 based on the second length of the material. The last OFDM symbol 3102 may be reduced from a first duration to a second duration (eg, modified OFDM symbol 3104) based on removing excessive padding using an FFT/IFFT relationship. The length of the cyclic prefix used can be the same for the entire subframe.

Figure 33 is an example of dynamic padding in each second subcarrier (1/2 data). The plurality of OFDM symbols can have a first duration. A plurality of OFDM symbols can be associated with a first length of material. For example, each of the plurality of OFDM symbols can transmit a first length of the material. Data may be placed in each second carrier, for example, when the data length (e.g., the second length) is greater than the length of the first duration of the last OFDM symbol 3202 and less than or equal to the duration of the last OFDM symbol 3202. 1⁄2 of time. When performing IFFT of an OFDM symbol, the generated time domain symbol may be a periodicity having two periods. The second period can be removed and the modified symbol duration 3204 can be sent. The modified symbol 3204 can be 1⁄2 of the last OFDM symbol 3202. For example, the last OFDM symbol 3202 can be modified from a first duration to a second duration (eg, modified OFDM symbol 3204) based on the length of the material. The last OFDM symbol 3202 may be reduced from a full OFDM symbol duration to a partial OFDM symbol duration (eg, modified symbol 3204) based on removing excessive padding using FFT/IFFT relationships. The length of the cyclic prefix used can be the same for the entire subframe.

The data can be transmitted normally, for example, when the data length is greater than 1⁄2 of the first length of the material transmitted in the last OFDM symbol 3202.

Figure 34 is an example of dynamic padding of two truncated OFDM symbols transmitted (e.g., 3/4 data) for a duration of 1⁄4 and duration. Two truncated OFDM symbols of duration 1⁄2 and duration may be transmitted, for example, when the data is greater than the first length of the last OFDM symbol 3302 but less than or equal to the first length of the last OFDM symbol 3302 3⁄4 hours. A data equal to 1⁄2 of the length of the last OFDM symbol 3302 can be placed in each of the second subcarriers. When performing IFFT of an OFDM symbol, the generated time domain symbol may be a periodicity having two periods. The second period can be removed and a symbol duration of 3304 can be sent. The remaining data can be placed in each of the fourth subcarriers. When the IFFT of the OFDM symbol is performed, the generated time domain symbol may be a period having four periods. The last three cycles can be removed and a symbol duration of 3306 can be sent. For example, the 1⁄2 duration of the last OFDM symbol 3302 and the two symbols of the 1⁄4 duration may be transmitted. The length of the cyclic prefix used can be the same for the entire subframe.

In an example of blind estimation, the receiver may estimate the duration of the last OFDM symbol based on the length of the frame in the MAC or PHY header. In the example of messaging, the receiver can obtain the length of the last OFDM symbol in the frame.

The receiver can map the received data to a 256-length symbol, such as by four times copying the received signal, for example, when the data length is less than 1⁄4 of the first length of the data. When the symbol is FFT, the resulting frequency domain symbol can replicate the original transmitted signal. The receiver can also perform a 64-point FFT on the received signal and map it to each fourth subcarrier in the frequency domain.

The receiver can map the received data to 256-length symbols, such as by copying the received signal twice, for example, when the data length is less than 1⁄2 of the length of the last OFDM symbol. When the symbol is FFT, the resulting frequency domain symbol can replicate the original transmitted signal. The receiver can also perform a 128-point FFT on the received signal and map it to each second subcarrier in the frequency domain.

The receiver can process the data normally, for example when the data length is greater than 1⁄2 of the length of the OFDM symbol.

Figure 35 is an example of dynamic padding in an OFDMA transmission. The disclosed techniques can be used for OFDMA transmission, for example, when a STA in an OFDMA transmission has a last transmission of one of the previously discussed lengths, for example, a maximum length.

A smaller number of subcarriers and/or low modulation and decoding schemes for transmission may limit the maximum allowed PSDU size. For example, 9 bits can be used to signal the length in the SIG field in an 802.11ah 1 MHz bandwidth format (eg, 26 available subcarriers). 9 bits can be used to signal a PSDU of up to 511 bytes or 511 OFDM symbols. 511 OFDM symbols may carry more than 511 bytes or less than 511 bytes, for example, depending on the modulation and decoding scheme used. A 511 OFDM symbol can carry more than 511 bytes, for example, when the MCS value is high and each OFDM symbol carries a large number of information bits. 511 OFDM symbols may carry less than 511 bytes, for example, when the MCS value is low and each OFDM symbol carries a limited number of information bits. The maximum allowed PSDU size can be limited to 511 bytes (eg, in these cases) and the TCP packet can contain approximately 1500 bytes, eg, the PSDU size can be less than (eg, significantly less than) the TCP packet size .

The maximum allowed PSDU size can be limited (eg, limited to a specific number). An example may be when OFDMA is used and when the smallest RU has 26 subcarriers.

The length field can be carried in the SIG field (eg, in the PLCP report). The length field may define the length of the PSDU (eg, current PSDU) in units of bytes or in units of OFDM symbols. The maximum allowed PSDU size can be limited by the design of the length field, for example, due to the limited size of the SIG field.

One or more length field designs are available. The length field can be signaled in the SIG-A and/or SIG-B fields. The length field can be extended by using one or more other fields. For example, the SIG field can include a length field, an MCS field, and/or an aggregate field. The length field can be multiple bytes, for example, when the aggregate field is off (OFF). The length field can be multiple OFDM symbols, for example, when the aggregate field is turned "ON".

In an example, one or more of the following may be applied. Two or more MCS sets (eg, MCS Set 1 and MCS Set 2) can be defined. MCS set 1 may correspond to a high MCS value. MCS set 2 may correspond to a low MCS value. MCS Set 1 and MCS Set 2 may not overlap. MCS Set 1 and MCS Set 2 may (e.g., by a combination of MCS Set 1 and MCS Set 2) override the MCS values used in the system (e.g., all MCS values).

The value of the aggregation field can depend on the set of MCS used. For example, for MCS Set 1, the aggregation field can be set to On. For MCS Set 2, the aggregation field can be set to off. The aggregation field can be used as a length extension field, for example, when the receiver implicitly obtains the aggregated value from the MCS value. The receiver may implicitly obtain aggregated values from the MCS values, for example, when using MCS set-aggregation setup mapping (as described herein) and/or signaling MCS values. The bit(s) used to aggregate the fields along with the original length field may be used to indicate a range of PSDU sizes (eg, a wider range of PSDU sizes).

The Network Allocation Vector (NAV) may include virtual carrier sensing. The MAC header in the frame may include a duration field. The Duration field specifies the specified transmission time for the frame request. Wireless media may be busy, for example, during transmission time. STAs listening via wireless media can read the duration field and set its NAV (eg, based on the duration field). The NAV can instruct the STA to postpone (e.g., must delay) how long to access the wireless medium.

More than one MAC frame can be transmitted simultaneously, for example, when there is a DL MU transmission (eg, OFDMA transmission). Each MAC header can include a duration field. The STA may detect a PHY header containing the SIG-A and/or SIG-B fields. The STA can determine if it is a potential receiver for transmission. In the case where the STA is not the desired receiver for this DL MU transmission, for example, instead of rejecting the reception transmission and going to the power save mode, the STA may need (eg, must) detect each MAC frame carried in the MU transmission. And set its NAV accordingly. This NAV setup process reduces power efficiency. An undesired STA can determine how long it has delayed (eg, must be deferred) without detecting each MAC frame.

Virtual carrier sensing is available. More than one desired response frame for the current DL MU transmission may exist with the MU transmission. One or more unintended STAs may utilize response frames having the longest OFDM symbol duration, for example, to set their MU Allocation Vector (MAV). The MAV can instruct the STA to delay (eg, must delay) how long to access the channel media. The PLCP header (eg, (HE) SIG-A and/or SIG-B fields) may carry a MU Response Indication (MRID), such as with a DL MU transmission. One or more unintended STAs may use the MRID to set the MAV. For example, one or more of the following may be applied to the AP side and/or the STA side.

For the AP, one or more of the following can be applied. The PLCP header transmitted by the DL MU may contain the MRID value. The MRID value set can be defined to classify different possible response frames. The response frame may include one or more of the following: UL data frame; UL management frame, such as probe request, (re)authentication request, (re)association request, etc.; or UL control frame, eg, PS - Polling, (MU-) CTS, CF-End (CF-End), ACK, Block ACK, etc. Based on the size of the potential response frame, N MRID values can be defined. Each of the N MRID values can be used to indicate a duration range. The duration range can vary by units of microseconds or multiples of microseconds. The MRID value can linearly represent the duration range. For example, MRID = 0 may indicate a duration range [0, D-1], and MRID = 1 may indicate a duration range [D, 2D-1], and the like. The MRID value can represent the duration range in the form of an exponent. For example, MRID=0 may indicate a duration range [0, 2^D-1], and MRID=1 may indicate a duration range [2^D, 2^(2D)-1], and the like. With MU transmission, the AP can schedule one or more UL MU response frames. With MU transmission, the AP can estimate the size of the response frame. The AP can identify the longest transmission duration from UL users (eg, each UL user). The longest transmission duration may be a function of the response frame size, the MCS assigned or suggested for the UL frame transmission, and/or the resources allocated for the UL frame transmission. The AP can determine the MRID value by comparing the longest transmission duration to the duration range.

For the STA side, one or more of the following may be applied. The STA may receive resource allocation information in the PLCP header, for example, when the STA is the intended receiver for the DL MU transmission. Thus the STA can receive and/or detect TCP packets on one or more assigned Rus. The STA may check the MRID value in the PLCP header, such as when the STA is not the intended receiver for the DL MU transmission. The MRID counter can begin at the end of the DL MU transmission. The DL MU PPDU(s) may include one or more PSDUs, where each PSDU may include its own duration field (eg, in a corresponding MAC header). One or more of the following may be applied (eg, when the PSDU(s) carried by the MU PPDU contains its own duration field): the STA may be postponed based on the longest NAV value, eg, when the STA succeeds Each of the PSDUs is detected; or the STA may postpone and ignore the obtained NAV based on the MAV, such as when the STA does not detect each of the PSDUs in the DL MU transmission.

The processes and tools described herein can be applied in any combination and can be applied to other wireless technologies and other services.

Although the disclosed features, elements, and techniques (eg, disclosed techniques) are described in a plurality of examples with multiple combinations, each feature, element or technique can be implemented separately and with other described features, elements and techniques. It is implemented with different combinations of combinations and non-bindings.

While the examples are presented in relation to 802.11, the disclosed techniques are applicable to other wireless systems and protocols.

Although the examples are presented in Inter-Short Interframe Space (SIFS) format to indicate multiple inter-frame spacing, the disclosed techniques can be applied to other inter-frame spacing applications, such as reduced inter-frame spacing (RIFS) or other agreed time. interval.

A WTRU may refer to the identity of an entity device or the identity of a user, such as an identity associated with a subscription, such as an MSISDN, SIP URI, and the like. A WTRU may refer to an application based identity, such as a username that can be used in each application.

The processes described above can be implemented in a computer program, software or firmware embodied on a computer readable medium, executed by a computer or processor. Examples of computer readable media include, but are not limited to, electronic signals (transmitted over wired and/or wireless connections) and/or computer readable storage media. Computer readable storage media includes, but is not limited to, read only memory (ROM), random access memory (RAM), scratchpad, cache memory, semiconductor storage devices, magnetic media (such as but not limited to internal hard drives and A removable disk), a magneto-optical medium, and/or an optical medium (such as a CD-ROM disk and/or a digital versatile disk (DVD)). A processor associated with the software can be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

BER‧‧‧Bit rate
BSS‧‧‧Basic Service Set
MAC‧‧‧Media Access Control
MCS, 706, 804‧‧‧ modulation and decoding scheme
OFDMA‧‧ Orthogonal Frequency Division Multiple Access
PLCP‧‧‧ physical layer convergence process
RF‧‧‧RF
SC‧‧‧Subchannel
100‧‧‧Communication system
102‧‧‧Access Point (AP)
102a, 102b, 102c, 102d‧‧‧WTRU (wireless transmitting and receiving unit)
104‧‧‧Wireless Access Network (RAN)
1069‧‧‧ Core Network
108‧‧‧Public Switched Telephone Network (PSTN)
110, 112‧‧‧ Station (STA)
114‧‧‧Network
114a, 114b‧‧‧ base station
116‧‧‧Intermediate mediation
118‧‧‧Processor
120‧‧‧ transceiver
122‧‧‧Send/receive unit
124‧‧‧Speaker/Microphone
126‧‧‧Digital keyboard
128‧‧‧Display/Touchpad
130‧‧‧Cannot remove memory
132‧‧‧Removable memory
134‧‧‧Power supply
136‧‧‧Global Positioning System (GPS) chipset
138‧‧‧ Peripherals
OFDMA numerology of 200‧‧‧20 MHz components
OFDMA numerology of 300‧‧.40 MHz components
OFDMA numerology of 400‧‧80 MHz components
702, 802‧‧‧RU allocation field
708, 806‧‧‧N _StS
1010, 1210, 1510, 1710, 1810, 1910, 2826‧‧‧ STA information fields
704, 1012, 1212, 1514‧‧‧ STA ID field
1014, 1214, 1526‧‧‧RU starting position field
1016‧‧‧RU interval field
1018, 1218, 1522, 1532, 1722, 1822, 1922‧‧‧ MCS fields
1020, 1220, 1524, 1534, 1724, 1824, 1924‧‧‧N _sts fields
1216, 1528‧‧‧RU quantity field
1512‧‧‧STA separated symbol field
1520‧‧‧RU field
1716‧‧‧1D min_RU bitmap field
1720‧‧‧RU size indication field
1816, 1820‧‧‧RU field
1920‧‧‧2D RU dot matrix field
2802‧‧‧PLCP header
2804‧‧‧MAC header
2806‧‧‧Session information field
2808‧‧‧FCS field
2810‧‧‧session number field
2812‧‧‧Time offset field
2814‧‧‧Session type field
2816‧‧‧ Duration field
2818‧‧‧Group ID field
2820‧‧‧ assigned number field
2822‧‧‧One or more allocation fields
2824‧‧‧ Index field
2828‧‧‧ Resource field
3302‧‧‧Last OFDM symbol
3204‧‧‧Modified OFDM symbols

Figure 1A shows an exemplary wireless local area network (WLAN) device. FIG. 1B is a diagram of an exemplary communication system in which one or more of the disclosed features may be implemented. FIG. 1C depicts an exemplary wireless transmit/receive unit WTRU. Figure 2 is an example of OFDMA numerology for a 20 MHz component. Figure 3 is an example of OFDMA numerology for a 40 MHz component. Figure 4 is an example of OFDMA numerology for an 80 MHz component. Figure 5 is an exemplary power spectral density of a partially loaded OFDM signal with RF I/Q imbalance. Figure 6 is an example of the bit error rate (BER) performance of the interfered signal. Figure 7 is an exemplary format of a RU allocation domain. Figure 8 is an exemplary format of a RU allocation domain. Figure 9 is an example of a tone plan and RU unit tag for the 20 MHz band. Figure 10 is an example of decentralized RU messaging with fixed STA information size. Figure 11 is an example of a distributed RU schedule. Figure 12 is an example of a continuous RU message with a fixed STA information size. Figure 13 is an example of a continuous RU schedule. Figure 14 is an example of a contiguous RU allocation with multiple RU sets. Figures 15A and 15B are examples of a continuous RU messaging domain design with variable STA information size. Figure 16 is an example of flat RU messaging. Figures 17A and 17B are examples of flattening RU communications. Figures 18A and 18B are examples of flattening RU messaging. Figures 19A and 19B are examples of flattening RU communication. Figure 20 is an example of a limited RU allocation for the 20 MHz band. Figure 21 is an example of type 1 messaging that explicitly signals the number of STAs. Figure 22 is an example of type 1 messaging that explicitly signals the number of STAs. Figure 23 is an example of type 2 messaging that implicitly signals the number of STAs. Figure 24 is an example of type 2 messaging that implicitly signals the number of STAs. Figure 25 is an example of type 2 messaging that implicitly signals the number of STAs. Figure 26 is an example of the minimum allowable bandwidth. Figure 27 is an example of a limited number of allowed bandwidths. Figure 28 is an example of a resource allocation frame format. Figure 29 is an example of the resource allocation frame announced parameters indicating resource allocation for future sessions. Figure 30 is an example of a narrow band allocation for Internet of Things (IoT) operations. Figure 31 is an example of symmetric RU allocation. Figure 32 is an example of dynamic padding in each of the fourth subcarriers (1/4 data). Figure 33 is an example of dynamic padding in each second subcarrier (1/2 data). Figure 34 is an example of dynamic padding of two truncated OFDM symbols of length 1⁄4 and length 1⁄2 transmitted (3/4 data). Figure 35 is an example of dynamic padding in an OFDMA transmission.

MAC‧‧‧Media Access Control

3202‧‧‧Last OFDM symbol

3204‧‧‧Modified OFDM symbols

Claims (22)

A method of transmitting a protocol data unit (PDU), the method comprising: mapping data to a plurality of OFDM symbols of the PDU, wherein each of the plurality of OFDM symbols is associated with a first duration, and wherein And each of the plurality of OFDM symbols is associated with a first length of the data; determining that a second length of the data transmitted in a last OFDM symbol of the plurality of OFDM symbols is less than or equal to the first portion of the data a length of 1⁄4, 1⁄2 or 3⁄4; based on a second length of the data, modifying the last OFDM symbol from the first duration to a second duration, wherein the second duration is the first duration And transmitting an indication of the second duration associated with the last OFDM symbol in a PHY header, wherein the indication indicates that the second duration is the first duration 1⁄4, 1⁄2 or 3⁄4. The method of claim 1, wherein the last OFDM symbol is modified to be 1⁄4 of the first duration when the second length of the data is less than or equal to 1⁄4 of the first length of the material. The method of claim 1, wherein the last OFDM symbol is when the second length of the material is greater than 1⁄4 of the first length of the material and less than or equal to 1⁄2 of the first length of the material. Modified to 1⁄2 of the first duration. The method of claim 1, wherein the last OFDM symbol is modified when the second length of the material is greater than 1⁄2 of the first length of the material and less than or equal to 3⁄4 of the first length of the material. For the first duration of 3⁄4 The method of claim 1, wherein modifying the last OFDM symbol from the first duration to the second duration comprises using an inverse FFT (IFFT) relationship for the last in the time domain. The OFDM symbol produces the second duration. The method of claim 5, wherein modifying the last OFDM symbol from the first duration to the second duration further comprises removing one or more redundancy periods due to using the IFFT relationship . The method of claim 1, wherein the method further comprises generating a periodic symbol based on the second duration of the last OFDM symbol. The method of claim 1, wherein the first length of the data is associated with a maximum data length carried in an OFDM symbol. The method of claim 1, wherein the PDU is a Physical Layer Convergence Procedure (PLCP) PDU (PPDU). The method of claim 1, wherein the first length of the material and the second length of the material are associated with one of the available carriers. The method of claim 1, wherein the indication indicates that the second duration is equal to the first duration when the second length of the material is greater than 3⁄4 of the first length of the data. An access point (AP), the access point comprising: a processor configured to: map data to a plurality of OFDM symbols of a protocol data unit (PDU), wherein each of the plurality of OFDM symbols Associated with a first duration, and wherein each of the plurality of OFDM symbols is associated with a first length of data; determining data transmitted in a last OFDM symbol of the plurality of OFDM symbols a second length less than or equal to 1⁄4, 1⁄2 or 3⁄4 of the first length of the data; based on the second length of the data, modifying the last OFDM symbol from the first duration to a second duration, wherein The second duration is 1⁄4, 1⁄2 or 3⁄4 of the first duration; and transmitting an indication of the second duration associated with the last OFDM symbol in a PHY header, wherein the indication indicates the The second duration is 1⁄4, 1⁄2 or 3⁄4 of the first duration. The AP of claim 12, wherein when the second length of the data is less than or equal to 1⁄4 of the first length of the material, the last OFDM symbol is modified to be 1⁄4 of the first duration. The AP of claim 12, wherein when the second length of the material is greater than 1⁄4 of the first length of the material and less than or equal to 1⁄2 of the first length of the material, the last OFDM symbol is Modified to 1⁄2 of the first duration. The AP of claim 12, wherein when the second length of the data is greater than 1⁄2 of the first length of the material and less than or equal to 3⁄4 of the first length of the material, the last OFDM symbol is Modified to 3⁄4 of the first duration. The AP of claim 12, wherein configuring to modify the last OFDM symbol from the first duration to the second duration comprises using an inverse fast Fourier transform (IFFT) relationship to The second duration is generated for the last OFDM symbol in the time domain. The AP of claim 16, wherein the being configured to modify the last OFDM symbol from the first duration to the second duration further comprises being configured to remove due to use of the IFFT relationship One or more redundancy cycles. The AP of claim 12, wherein the processor is further configured to generate a periodic symbol based on a second duration of the last OFDM symbol. The AP of claim 12, wherein the first length of the data is associated with a maximum data length carried in one OFDM symbol. The AP of claim 12, wherein the PDU is a Physical Layer Convergence Procedure (PLCP) PDU (PPDU). The AP of claim 12, wherein the first length of the material and the second length of the data are associated with a number of available carriers. The AP of claim 12, wherein when the second length of the material is greater than 3⁄4 of the first length of the data, the indication indicates that the second duration is equal to the first duration.