WO2019149340A1

WO2019149340A1 - Synchronization in a wlan

Info

Publication number: WO2019149340A1
Application number: PCT/EP2018/052254
Authority: WO
Inventors: Genadiy Tsodik; Shimon SHILO; Doron Ezri; Avi WEITZMAN; Oded Redlich; Ming GAN
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2018-01-30
Filing date: 2018-01-30
Publication date: 2019-08-08

Abstract

In some embodiments disclosed herein a device 102 for network communication transmits an outbound WLAN frame to a remote device 104 via the network 100. The outbound frame includes a frame synchronization portion 802 followed by first ODFM. The device also receives an inbound WLAN frame 808 from the remote device. The inbound frame includes second OFDM symbols. One of: (a) the transmitted outbound frame and (b) the inbound frame, includes generation data 821 for generating the other of the outbound frame, by the device, and the inbound frame, by the remote device. The frame synchronization portion suspends transmission of the first OFDM symbols to be synchronized with the second OFDM symbols. Corresponding methods, computer programs and non-transient computer readable mediums are also disclosed.

Description

SYNCHRONIZATION IN A WLAN

BACKGROUND

The present invention, in some embodiments thereof, relates to a device, method and program product for use in Wireless Local Area Network (WLAN) communication.

Wi-Fi protocols (defined by the IEEE 802.11 suite of standards, herein referred to as 802.11) are popularly employed by many modem devices for WLAN communication. Some WLAN protocols, notably in WiFi, transmit WLAN frames having a payload encoded in Orthogonal Frequency Division Multiplexing (OFDM) symbols spaced by a guard interval, in the form of a cyclic prefix. However, in environments having multiple WLAN frames being transmitted from different sources there is potential for overlapping OFDM symbols in different WLAN frames to interfere with each other.

There is therefore an increasing need to develop WLAN solutions that operate well in crowded environments.

SUMMARY

It is an object of the present invention to provide an apparatus, a computer program product, and a method for network communication in WLAN environments in which multiple WLAN frames are transmitted in overlapping time periods. The foregoing and other objects are achieved by the features of the independent claims.

Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect of the invention, there is provided a device for network communication. The device comprises at least one processor. The at least one processor is configured to instruct a transmission of an outbound Wireless Local Area Network, WLAN, frame to a remote device via the network. The outbound frame includes a frame synchronization portion followed by first Orthogonal Frequency Division Multiplexing, ODFM, symbols. The at least one processor is further configured to receive an inbound WLAN frame from the remote device. The inbound frame includes second OFDM symbols. One of: (a) the transmitted outbound frame and (b) the inbound frame, includes generation data for generating the other of the outbound frame, by the device, and the inbound frame, by the remote device. The frame synchronization portion suspends transmission of the first OFDM symbols to be synchronized with the second OFDM symbols.

The synchronization of the OFDM symbols, most beneficially in the case of being synchronized to within the cyclic prefix, has an advantage of potentially reducing interference between the first OFDM symbols and the second OFDM symbols.

The suspension of transmission occurs by the frame synchronization portion being generated in one of two ways.

The first way is used for cases in which the generation data is included in the outbound frame. For such cases, the frame synchronization portion is generated to have a commencement after the generation data and a duration that is dependent on a known delay and a duration that is dependent on a known delay involved in communicating with the remote device. This first way is in some embodiments used for simultaneous transmission and reception (STR) communication in which an access point (AP) transmits the outbound frame, and a non-AP station (STA) responds by transmitting the inbound frame.

In some embodiments, the known delay involved in communicating with the remote device comprises a processing time between the remote device receiving the generation data and transmitting said inbound frame. The at least one processor is further configured to determine said duration.

In some embodiments, the known delay involved in communicating with the remote device also comprises a time of flight attributed to the inbound frame and a time of flight attributed to the outbound frame. In some embodiments, the frame synchronization portion comprises at least one of: a lengthened portion of at least one of a signal field that includes the generation data; and a lengthened portion of a training field that follows the generation data.

In some embodiments, the outbound frame includes an indicator for identifying the frame synchronization portion. The second way is used for cases in which the generation data is included in the inbound frame. In such cases the frame synchronization portion is generated to have at least one of a commencement time and a duration that is dependent on an interval between (i) the generation data and (ii) a start of an initial one of the second OFDM symbols. This second way is in some embodiments used for STR communication in which a non-AP STA transmits the inbound frame, and in response, an AP transmits the outbound frame.

In some embodiments, the frame synchronization portion comprises an extended portion of a training field that is a first field of the outbound frame. Thus, the synchronization portion is, in some embodiments, extends the overall duration of the frame in which it is included, in comparison with a frame in which the synchronization portion is not included.

In a second aspect of the present invention, there is provides a method for network communicating. The method comprises, at a first device, instructing transmission of an outbound Wireless Local Area Network, WLAN, frame to a remote device. The outbound frame includes a frame synchronization portion followed by first Orthogonal Frequency Division Multiplexing, ODFM, symbols. The method also comprises, at the first device, receiving an inbound WLAN frame from the remote device, the inbound frame including second OFDM symbols. One of: (a) the outbound frame and (b) the inbound frame, includes generation data for generating the other of the outbound frame, by the first device, and the inbound frame, by the remote device. The frame synchronization portion suspends transmission of the first OFDM symbols to be synchronized with the second OFDM symbols by being generated according to any one of two ways. A first of the ways is employed is used for cases in which the generation data is included in the outbound frame. In such cases the frame synchronization portion is generated to have a commencement after the generation data and a duration that is dependent on a known delay and a duration that is dependent on a known delay involved in communicating with the remote device. A second of the ways is employed for cases in which the generation data is included in the inbound frame. In such cases, the frame synchronization portion is generated to have at least one of a commencement time and a duration that is dependent on an interval between (i) the generation data and (ii) a start of an initial one of the second OFDM symbols. Each of the embodiments of the first aspect of the invention are also applicable to the second aspect of the invention. In some implementations of the first or second aspect of the invention, the transmission of the first OFDM symbols and reception of the second OFDM symbols are synchronized at the device, to within a cyclic prefix that spaces the first OFDM symbols and spaces the second OFDM symbols. In some implementations of the first or second aspect of the invention, the generation data encodes one or more of the following parameters that correspond to the OFDM symbols of said one of the transmitted outbound frame and the inbound frame: a frame format; modulation and coding scheme (MCS) data; and guard interval data. The generation data may, as part of the frame format or otherwise, encode a duration of each of the OFDM symbols. A remote device that receives the guard interval and the duration of each of the OFDM symbols, can use this information to define format the OFDM signals said other of the inbound frame and the outbound frame to match the format of the OFDM signals in said inbound frame and the outbound frame transmitted to said remote device. In this manner, not only are that the transmission of the first OFDM symbols and transmission of the second OFDM symbols synchronized at the start of the respective transmissions, but each of the symbols in the first OFDM symbols and each of the symbols in the second OFDM symbols are also synchronized. In other embodiments, the format of the OFDM symbols is pre-configured to be the same, so the cyclic prefix and the duration data of the OFDM symbols need not be transmitted for there to be synchronization for all of the OFDM symbols. However, in any case, it will be understood that in some the OFDM symbols of inbound frame and the OFDM symbols in the outbound frame have a matching format with regards to symbol duration a cyclic prefix. Frame format information, optionally included in the generation data, may include such OFDM symbol format information and/or may include a measure of a duration of the preamble portion of the frame (i.e. the portion of the frame up to the OFDM data payload) of a leading/instigating frame in an STR communication. For example, in the case of said second way of implementing the invention, the frame format information may tell an AP that receives the format information when the UP OFDM symbols will arrive, and in response, the AP can transmit a DL frame having a strong of OFDM symbols starting at the same time as one of the UL OFDM symbols is received. The frame format information may also provide a device receiving the leading frame with knowledge of the duration of the payload and/or size of the leading frame, so that the STR frame transmitted in response to the leading frame finishes being transmitted at the same time as the leading frame. In some implementations of the first or second aspect of the invention, at least one of the OFDM symbols of said other of the outbound frame and the inbound frame encodes transmission parameters including one or more of: MCS data; and guard interval data. The at least one of the OFDM symbols may encode frame format data, and/or a duration of each of the OFDM symbols, the frame duration being defined either as part of, or being separate to, the frame format data. Ordinarily in WiFi, such encoded information is included in a legacy preamble. However, in some embodiments of the present invention the legacy preamble is omitted from the start of said other of the outbound frame and the inbound frame. For such embodiments, such encoded information may therefore instead be included in said at least one of the OFDM symbols.

In some implementations of the first or second aspect of the invention, the device is an access point of a wireless local area network.

In a third aspect of the second invention, there is provided a device comprising at least one processor. The at least one processor is configured to receive an inbound Wireless Local Area Network, WLAN, frame from a remote device via the network, the inbound frame including a frame synchronization portion followed by first Orthogonal Frequency Division Multiplexing, ODFM, symbols. The at least one processor is further configured to instruct transmission of an outbound frame, the outbound frame including second OFDM symbols. One of the transmitted outbound frame and the inbound frame includes generation data for generating the other of the outbound frame, by the device, and the inbound frame, by the remote device. The frame synchronization portion suspends reception of the first OFDM symbols to be synchronized with the second OFDM symbols by any one of two ways. A first of the ways is employed in cases in which that the generation data is included in the inbound frame. In such cases, the frame synchronization portion is generated to have a commencement after the generation data and a duration that is dependent on a known delay and a duration that is dependent on a known delay involved in communicating with the device. This first way is in some embodiments used for STR communication in which an AP transmits the inbound frame, and in response, a non-AP STA transmits the outbound frame.

A second of the ways is employed in cases in which the generation data is included in the outbound frame. In such cases the frame synchronization portion is generated to have at least one of a commencement time and a duration that is dependent on an interval between (i) the generation data and (ii) a start of an initial one of the second OFDM symbols. This second way is in some embodiments used for STR communication in which a non-AP STA transmits the outbound frame, and in response, an AP transmits the inbound frame.

In a fourth aspect of the present invention, there is provided a method for network communicating. The method comprises, at a first device, receiving an inbound Wireless Local Area Network, WLAN, frame from a remote device via the network. The inbound frame includes a frame synchronization portion followed by first Orthogonal Frequency Division Multiplexing, ODFM, symbols. The method further comprises, at the first device, instructing transmission of an outbound frame, the outbound frame including second OFDM symbols. One of the transmitted outbound frame and the inbound frame includes generation data for generating the other of the outbound frame, by the device, and the inbound frame, by the remote device. The frame synchronization portion suspends reception of the first OFDM symbols to be synchronized with the second OFDM symbols by one of two ways. A first of the ways is employed for cases in which the generation data is included in the inbound frame. In such cases the frame synchronization portion is generated to have commencement after the generation data and a duration that is dependent on a known delay involved in communicating with the device. A second of the ways is employed for cases in which the generation data is included in the outbound frame. In such cases, the frame synchronization portion is generated to have at least one of a commencement time and a duration that is dependent on an interval between (i) the instructions and (ii) a start of an initial one of the second OFDM symbols. In some implementations of the third or fourth aspect of the invention, the device is a non-AP STA of a wireless local area network. Thus, embodiments of the third and fourth aspects of the present invention mirror embodiments of the first and second aspect of the present invention, respectively, and are applicable to the first and second aspect of the present invention, bearing in mind that the outbound frame in the first and second aspects of the present invention corresponds to the inbound frame in the third and fourth aspects of the present invention. For the same reason, the inbound frame in the first and second aspects of the present invention corresponds to the outbound frame in the third and fourth aspects of the present invention.

In a fifth aspect of the present invention there is provides a computer program with a program code for performing a method according to the second of fourth aspects of the present invention, when the computer program runs on one or more processing devices. In a sixth aspect of the present invention there is provides a non-transient computer readable medium storing thereon instructions for performing a method according to the second of fourth aspects of the present invention, when instructions are executed by at least one processor. Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced. In the drawings:

FIG. 1 is a conceptual diagram of a wireless network including a first device in accordance with an aspect of the present invention and a plurality of second devices that are in accordance with one or more embodiments of the present invention;

FIG. 2 is a conceptual block diagram that is depicting a device, or a part of a device, that is in accordance with one or more embodiments of the present invention;

FIG. 3 is a conceptual block diagram of a chip that is in accordance with an embodiment of the device; FIG. 4 is a diagram depicting a format of a frame transmitted used in one or more embodiments of the present invention;

FIG. 5 is a diagram depicting a legacy part of a preamble that is included in the frame format; FIG. 6 is a diagram depicting a protocol-specific part of the preamble;

FIG. 7 illustrates an exemplary unsynchronized STR communication, led by a downlink frame;

FIG. 8 illustrates an exemplary STR communication, led by a downlink frame and being in accordance with one or more embodiments of the invention; FIG. 9A illustrates another exemplary STR communication, led by an uplink frame and being in accordance with one or more embodiments of the invention;

FIG. 9B illustrates another exemplary STR communication, led by an uplink frame and being in accordance with one or more embodiments of the invention;

FIG. 10 illustrates another exemplary STR communication, having a specialized preamble for an STR frame and being in accordance with one or more embodiments of the invention;

FIG. 11 illustrates another exemplary STR communication, having a specialized preamble for an STR frame including a signal field and being in accordance with one or more embodiments of the invention; and FIGS. 12A to 12D illustrate flow charts of various exemplary methods, each method being in accordance with one or more embodiments of the invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to a device, method and program product for use in Wireless Local Area Network (WLAN) communication. In terms not intended to limit the scope of the invention, some embodiments or one or more aspects of the invention involve a device for network communication that transmits an outbound WLAN frame to a remote device via the network. The outbound frame includes a frame synchronization portion followed by first ODFM symbols. The device also receives an inbound WLAN frame from the remote device. The inbound frame includes second OFDM symbols. One of: (a) the transmitted outbound frame and (b) the inbound frame, includes generation data for generating the other of the outbound frame, by the device, and the inbound frame, by the remote device. The frame synchronization portion suspends transmission of the first OFDM symbols to be synchronized with the second OFDM symbols. Advantageously, the synchronization of the OFDM symbols can potentially reduce interference between the first OFDM symbols and the second OFDM symbols. In this context, it should be understood that the term“first” in the phrase“first OFDM symbols” is not intended to necessarily imply that the“first OFDM symbols” are at the start of a chain of OFDM symbols, but rather, refer to a plurality of OFDM symbols, which may, in some embodiments, be a segment of chain of OFDM symbols, and are distinct from another plurality of OFDM symbols that are referred to herein as“second OFDM symbols”.

By enabling less interference between the first OFDM symbols and the second OFDM symbols, the invention also facilitates the utilization of simultaneous transmission and reception (STR) in WLAN at a given WLAN transceiver. This addresses a principal challenge in STR transmission, namely self- interference caused by the transmission signal adversely affecting the performance of the detection of the received signal. This may also reduce dependence on having to use expensive RF interference cancellation, and instead allow for potentially improved interference mitigation in a digital processing component that ordinarily processes the received signal after any RF interference cancellation. This may lead to lower requirements of the RF part and thus simpler RF design and possibly lower cost.

In some embodiments, the STR transmission involves uplink and downlink transmissions sharing frequency resources.

Referring now to the drawings, FIG. 1 illustrates a network 100, which in the embodiments described herein is a WLAN, but in other embodiments is another form of a wireless network. The network includes a plurality of a first computing node device 102 which wirelessly communicates with second computing node devices l04(a-d), 106 using a plurality of communication protocols. In this communication each device 102, 104, 106 can both transmit and receive information. The computing node devices 102, 104, 106 may be any electronic device that includes hardware, and any associated software, for administering communication via the protocol(s). Thus or example, the computing node devices 102, 104, 106 may be user equipment, a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant, a smartphone, a laptop, a netbook, a personal computer, a tablet, a camera or consumer electronics, and the like. However, in the exemplary embodiment illustrated in FIG. 1, the first computing node device 102 is a device that includes or consists of a WLAN Access Point (AP), and for ease of explanation is generally referred to hereinafter as an AP. The second computing node devices l04(a-d), 106 act as non-AP station (STA) clients to the AP and are respectively a WLAN extender l04a (which has acts as a non- AP STA to AP 102 and acts as an AP to further non-AP devices (not shown)), a smart phone l04b, a laptop l04c, a WLAN-enabled camera l04d, and a tablet 106.

The AP 102 operates according to a first protocol and/or one or more second protocols, depending on what protocol is required by the client devices 104, 106. In this example, client devices 104 are capable of communicating according to the first protocol and, in some embodiments, the second protocol(s), but the client device 106 is only capable of communicating according to the second protocol(s). In exemplary embodiments, the second protocol(s) comprises one or more of IEEE 802.1 la, 802.1 lg, 802.1 ln, 802.1 lac, and 802.1 lax, i.e. one or more Wi-Fi protocols. Each of these protocols involve transmission of a WLAN legacy pre-amble that consists of Wi-Fi fields L-STF (legacy short training field), L-LTF (legacy long training field) and L-SIG (legacy signal field). The legacy preamble is used by all of the aforementioned IEEE 802.11 protocols for back-compatibility of newer protocols with older protocols, whereby a device that operates only the older protocol will not try to control the transmission medium while the frame of the newer, but back-compatible first protocol is being transmitted. Subsequent frames will also be protected provided they are transmitted within a relevant inter-frame spacing defined by the older protocol.

An exemplary architecture of a device 200 for performing an embodiment of one or more aspects of the present invention is illustrated in FIG. 2. The illustrated architecture of device 200 can be used for either or both of node devices 102, 104. The exemplary architecture is depicted as block diagram illustrating principal conceptual components of an exemplary device 200, and principal connections between those components, to aid a person skilled in the art in performing the invention. Components and connections that are not included in the illustration may therefore nonetheless be understood to be present by the person skilled in the art.

As has been discussed, the device 200 may include any necessary computer hardware that would be understood by the person skilled in the art to needed to perform the functions of the above listed any other possible types of computing nodes. In the illustrated embodiment, the device 200 has a processing system 204 having one or more processors / execution devices. The processing system 204 communicates data with at least one computer readable storage medium in the form of memory 207, via a communication bus 209. The memory 207 has a system memory 208, a volatile memory 210 and a tangible, non-transient memory 212. The system memory may have a read only memory (ROM) that stores a basic input/output system (BIOS). The volatile memory may have a random access memory (RAM), such as dynamic random access memory (DRAM). The non-transient memory 212 may have a hard disk drive(s), a solid state drive(s), and/or a flash memory device(s) and the like, and may store an operating system (e.g. Microsoft Windows, Apple OSX, Unix, and Linux) and/or other program products for running for operating device 200. The computer readable storage medium for providing the non-transient memory 212 may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. The processing system 204 includes a microprocessor 206 that performs tasks by executing software in the form of instructions and data stored on, and read from, the system, volatile, and/or non-transitory memory 208, 210, and 212. The tasks performed by the microprocessor can be some or all of the tasks that form various aspects of the present invention. The instructions are, at least upon powering up the device 200, stored in the non-transient memory 212 or an external data storage device accessed by the computer processing system 202 via an I/O interface 214. In some embodiments, the software may be provided to computer processing system 202 via a wired or wireless communication over a communications interface 218, which provides a network interface. Thus as will be appreciated, computer readable program instructions described herein may be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, a wireless local area network (e.g. Wi-Fi), a wide area network (e.g. the Internet), and/or a cellular network, e.g. Long-Term Evolution (LTE). The communications interface 218 may have additional communications connections, including but not limited to, BlueTooth, ZigBee, and 3G etc. Each of the communications connections may be via a transceiver front end 220 that drives antenna module which may be a single antenna, or a series of antennas for providing beamforming. The transceiver front end 220 includes analog components and mixed analog and digital signal components. The mixed analog and signal components include a digital to analog converter (DAC) 222 that generates RF signals from one or more instructions from the processing system 204. In some embodiments, the one or more instructions include one or more binary data streams to be converted to an analog signal by the DAC 222. The microcontroller 240 may, in some embodiments (not shown), also include one or more control signals to further instruct the transceiver front end 220, e.g. to be control the DAC, an STR hardware interface 228 or an amplifier module (not shown).

The mixed analog and signal components include an analog to digital converter (ADC) 224 for converting received RF signals to digital form which are then processed by the processing system 204. The processing of the analog signal components are handled by an RF front end that includes an interference reduction module 226 that acts to minimize interference between the outbound signal from the DAC and the inbound signal to the ADC and the STR hardware interface 228, which can be any additional hardware understood by a person skilled in the art to be appropriate for simultaneously sending and receiving signals to the antenna module 221. In other embodiments there is no STR hardware interface 228, and in such embodiments different antenna modules can be used for transmitting and receiving signals.

Processing system 204 also includes a processor 230 that may be adapted to perform an embodiment of one or more aspects of the present invention. For example, the in some embodiments the processor 230 is adapted to perform a method of the present invention, for example by executing one or more tasks. In some embodiments, the tasks are provided in instructions stored in the non-transient memory 212. Thus, in some embodiments, the processor 230 may comprise electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PFA) that execute a computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform one or more aspects of the present invention. The processor 230 generates digital instructions that it forwards to the transceiver front end, and it receives the digital signal generated received by the transceiver front end 220. It is therefore convenient to herein refer to the processor 230 to as a transceiver back-end. In the context of the Open Systems Interconnection (OSI) of a telecommunication system, the processor operates digital aspects of the physical layer (PHY) of the OSI model, via digital PHY transmit module 232 and PHY receive module 234, operates the data link layer via data link transmit module 236 and data link receive module 238. In any case, in some embodiments the microcontroller 240 communicates with microprocessor 206 via a communications interface, such as SPI, SDIO, I²C, UART or GPIO. In some embodiments, at least a portion of the data link layer functions are performed by a microcontroller 240.

The processor 230 can include a RAM to enable data storage by the microcontroller 240, the transmit link modules 236, and the receive data link modules 238. Non-transient memory can also be included in the microcontroller 240 to configure the microcontroller’s operation. In other embodiments the processor 230 adapted to perform an aspect of the present invention is an application-specific integrated circuit (ASIC) chip.

In other embodiments some or all of the functions of processor 230 may be integrated into microprocessor 206. It will therefore be appreciated by a person skilled in the art that the processor 230 may be a processing component of a larger processing chip / integrated circuit, or may be a stand-alone processing chip. Further, as will be appreciated by a person skilled in the art that the processor 230 may alternatively be distributed amongst multiple chips.

FIG. 3 illustrates an exemplary embodiment of a processor 330, which is an exemplary embodiment of processor 230 in which the processor 230 is adapted as the back-end (i.e. digital end) of a WLAN transceiver. Features 232, 234, 236, 238, 240, 242 of processor 230 respectively correspond to features 332, 334, 336, 338, 340, 342, of processor 330. However, in processor 330 more specifically has a MAC transmit module 336 and MAC receive module 338 in place of the data link layer transmit and receive modules, respectively. A logical link control sublayer of the data link layer is included in microcontroller 330. The digital components of the PHY layer are provided by IEEE 802.11 compliant transmit and receive components 332 and 334, respectively. In some embodiments, the MAC transmit module 336 generates a MAC layer protocol data unit (MDPU) that includes an aggregated MAC layer data unit in the form of aggregated MAC service data unit (A-MSDU), the A-MSDU having been received from the logical link control sublayer, which generated it. The MAC transmit module forwards the MPDU to the PHY transmit component 332.

In some other embodiments, the MAC transmit module 336 generates an aggregated MAC layer data unit in the form of an A-MPDU, which the MAC transmit module 336 then forwards to the digital PHY transmit component 332. Optionally, the A-MPDU can include one or more A-MSDUs.

In either case, an aggregated MAC layer data unit (A-MPDU or A-MSDU) may be provided to the digital PHY transmit component 332. For exemplary embodiments illustrated hereinafter the PHY transmit component may be any OFDM based PHY component, and thus may be an IEEE 802.11 PHY component, such a PHY component of 802.1 la, 802.1 lg, 802.1 ln, 802.1 lac, 802.1 lax or future 802.11 technologies. However, in some embodiments, the PHY component is more specifically, or may include all features of, an 802.1 lax PHY component. The digital PHY transmit component 332 receives a relevant data unit from the MAC transmit module 336, the received data unit being a PHY service data unit (PSDU). From the PSDU, the digital PHY transmit component 332 generates a PHY protocol data unit (PPDU) that includes a data component generated by a PHY data generator and a header generated by a PHY preamble generator. The PHY data generator modulates and encodes the PSDU, e.g. using BPSK QPSK, 16-QAM, 64-QAM, 256-QAM or 1024-QAM, as in 802.1 lax. Other aspects of the applied modulating and coding scheme can also be in accordance with 802.1 lax.

The modulation and coding scheme is applied to each of a plurality of OFDM subcarriers having a defined bandwidth and being spread at difference frequencies that collectively span a total bandwidth of the PHY layer. The bandwidth of the PHY layer may be selected from any one of 20 MHz, 40 MHz, 80MHz and l60MHz, consistent with 802.1 lax.

The total number of OFDM tones/subcarriers may be selected to be a set of 26, 52, 106, 242, 484 or 996 OFDM tones/subcarriers, consistent with 802.1 lax. In some embodiments, each subcarrier has a bandwidth of 78.125 kHz. In some embodiments, all of the first subcarriers (i.e. the downlink resource unit(s)) can be used to transmit to a single one of the client devices 104. In other embodiments all of the first subcarriers can be used to transmit to each of a selected plurality of the client devices 104, i.e. by multi-cast transmission. In yet other embodiments all of the first subcarriers can be used to transmit to each of the client devices 104, by broadcast transmission.

However, in yet other embodiments of the present invention, the use of the first subcarriers is distributed between the pluralities of the client devices, whereby different client devices receive information on a different, non-overlapping subset of the first subcarriers. Thus the transmission is capable of a Frequency Divisional Multiple Access (FDMA) scheme. In embodiments described herein, the FDMA is achieved by Orthogonal Frequency Duplex Multiplex Access (OFDMA). Further, and in any case, a given set of OFDM tones may be shared by uplink and downlink transmissions. In the exemplary embodiments illustrated in the figures herein, the uplink and downlink transmissions may be on the same OFDM tones. The use OFDM tones can be advantageous in multipath environment and is consistent with Wi-Fi.

The aggregated MAC layer data unit may be an A-MSDU or A-MPDU (including, but not limited to, A-MPDUs that incorporate an A-MSDU), but in exemplary embodiments described hereinafter is an A-MPDU. The PHY data generator receives at least one, and in some embodiments plurality of, aggregated MAC layer data units to be transmitted within a given time interval. The PHY data generator modulates received aggregated MAC layer data units to respective subsets of a set of subcarriers.

The PHY data generator converts the coded and translated aggregated MAC layer data unit to the time domain by calculating an inverse Fast Fourier Transform (IFFT). The calculated signal is forwarded as a payload, with a PHY preamble, to the transceiver front end 220, which converts it to an analog signal and drives transmission of the analog signal, as a frame, from antenna 221.

The PHY preamble is generated by the PHY preamble generator. In some embodiments, the preamble (PA) of the payload is fronted by a legacy WLAN preamble, e.g. a Wi-Fi legacy preamble consisting of L-STF, L-LTF and L-SIG, with the L-SIG field defining a transmission time (duration) of the frame. Additionally preamble fields specific to the first, newer protocol are also generated by the PHY preamble generator. An example of such a preamble, which is be used for some embodiments of the present invention is a High Efficiency (HE) WLAN preamble, being a preamble in accordance with 802.1 lax. The HE preamble has a high efficiency (non-legacy) portion including a HE-SIG-A field; a HE-SIG-B field(s); a high efficiency short training field (HE-STF); and a high efficiency long training field (HE-LTF). At least the L-SIG, HE-SIG-A and the HE-SIG-B fields undergo an IFFT and before being forwarded to the transceiver front end 220. In some embodiments, the HE-LTF also undergoes an IFFT. In some embodiments, the L-STF field also undergoes an IFFT. Upon receiving a frame from another device, on antenna 221, the transceiver front end

220 filters the signal, performs interference reduction via module 226 and converts the signal to digital form via ADC 224 for processing by processor 230. In the more specific example of processor 230 being processor 330, the 802.11 digital PHY receiving component 334 performs an FFT, demodulates and decodes the received data, and performs forward error correction, before finally forwarding the data to the MAC receiving module 338 for higher level processing. The digital PHY receiving component 334 is compliant with the same protocol(s) for which the digital PHY receiving component 334 is compliant. In an event that the received data includes a trigger to transmit a signal, the microcontroller 340 identifies based on the trigger and received duration data, parameters for transmitting the signal, the parameters including the size of the payload to transmit and when to commence transmission of the frame containing the payload. The signal received by the device 200 has its payload on OFDM subcarriers.

In some embodiments the device 200 is an access point 102 whereby its transmitted signal is a downlink signal and its received signal is an uplink signal.

As has been discussed, the client device 104 may have the same architecture as the access point 102. However control over which subcarriers the client device transmits on may be dynamically allocated by a trigger that is included in the WLAN frame received from the access point 102.

In addition to the functions described above, the device 200 may have a variety of other hardware elements. For example, in some embodiments it may be any network-enabled computing device (e.g. a laptop, router etc., as has been described). For example I/O interface 214 may include one or more of a speaker, microphone, keypad, display/touchscreen etc., which may be integrally incorporated into the device. Additionally the device may include a peripherals interface 215 to connect with one or more ancillary devices such as a mouse, keyboard, monitor, scanner, projector, digital camera etc. An environmental sensing system 217 may also be included to provide for example, temperature sensing, or a global positioning system or to measure any other condition of the device’s environment. The device may also include an internal power source 219, such as a battery, which may be a rechargeable battery.

An exemplary frame format of a downlink PPDU frame 400 transmitted in embodiments of the present invention is illustrated in FIG. 4. The frame 400 includes a preamble consisting of a legacy WLAN preamble, and a preamble that is specific to the first protocol, which in some embodiments is a high efficiency portion 404 of HE preamble, as defined in IEEE standard Draft P802.l lax-D2.0, October 2017, which for the purpose of the present disclosure is assumed to be 802.1 lax, or as defined in US 2016/0165589 Al (US’589), published 9 June 2016, and titled“Trigger Frame Format For Orthogonal Frequency Division Multiple Access (OFDMA) communication”. The entire contents of each of US’589 and 802.1 lax are incorporated herein by reference.

A payload 406 is also included. The payload 506 is a data presented in accordance the legacy preamble 402 and the preamble specific to the first protocol, i.e. high efficiency preamble 404. The payload can be, or include, an aggregated MAC layer data unit. The legacy preamble 402 is illustrated in more detail in FIG. 5, showing that the legacy preamble 402 consists of an F-STF field 508, an F-FTF field 510 and an F-SIG field 512, as has been discussed herein. The protocol-specific preamble 404 is illustrated in more detail in FIG. 6. It includes an HE-SIG-A field 514, an HE-SIG-B field 516, a protocol specific short training field 518, and a protocol specific long training field(s) 520, each of these fields being consistent with high efficiency WEAN, as described.

HE-SIG-A includes, amongst other information, a transmission opportunity period (TxOP) field for defining the TxOP. When a client device 104 prepares an uplink frame it calculates how much time will be remaining in the TxOP. The time remaining in TxOP will be the received TxOP value minus SIFS minus the duration of the uplink frame. The calculated time remaining in TxOP is then included in the uplink frame. The HE-SIG-A 514 field also, inter alia, defines modulation and coding features of the HE-SIG-B field. The HE-SIG-B field includes a common information field can be used by all of client devices 104. The HE-SIG-B also field includes, inter alia, MCS information which may be used by the relevant client device to decode a payload 406. Such MCS information is provided on a per STA basis, whereby n STA specific fields are provided to provide MCS information specific to n respective client devices. Each station specific field also includes a MAC address field to address a specific client device 104.

Based on a trigger, which may for example be reception of the HE-SIG-B field, the client device(s) transmits an uplink frame having the uplink payload during a time interval in which the AP transmits a downlink frame.

An uplink PPDU, on the other hand, may include each of the fields described above for a downlink PPDU, but in some embodiments, excludes the HE-SIG-B field. In such embodiments an AP that received the HE-SIG-A field in the uplink PPDU generate a downlink PPDU in response to and during the same time interval in which the uplink PPDU is received. FIG. 7 depicts an exemplary STR communication 700 led by a downlink transmission.

In the case of HE WLAN a DL or UL frame, needs to decodes generation data, included in an HE-SIG-B (when receiving a DL frame) or HE-SIG-A (when receiving an UL frame), in order to understand the required parameters for an STR frame (a UL STR frame or a DL STR frame, respectively), and to decide to transmit the STR frame. This means that there is a decoding delay preventing an STR frame from starting immediately after receipt HE-SIG-B/A. In the case of the embodiment illustrated in FIG. 7, a first, DL frame 702 is transmitted, e.g. by AP 102. A non-AP STA (e.g. one or more of l04(a to d), but for simplicity is assumed hereinafter to be just l04b) finishes receiving the generation data at time 704, corresponding to the end of the HE-SIG-B field of the DL frame 702. However, there is a processing delay 706 in the non- AP STA 104, before the non-AP STA l04b commences transmission of the UL STR frame 108. Further, in some network configurations there may a significant distance between the AP 102 and the non-AP STA l04b, leading to a non-negligible time-of- flight delay that further separates the respective commencements of the DL and UL frame transmissions. The DL frame 702 and the UL frame 108 have respective data payloads in OFDM signals 712 and 718, respectively. Each of the OFDM signals is of multiple OFDM symbols 716, 720. In the example illustrated in FIG 7, all of the OFDM symbols are marked as being data symbols, but other examples the OFDM signal include part of the preamble, such as the HE-LTF field Each of the OFDM symbols have a common duration 722, and are separated by a cyclic prefix 724, each cyclic prefix having the same guard interval length (cyclic prefix duration). As can be seen from FIG. 7, none of the OFDM symbols 716 of the downlink OFDM signal are synchronized with any of the OFDM symbols 720 of the uplink OFDM signal. FIG. 8 depicts an STR WLAN communication 800, as seen at either AP 102 or at least one non-AP STA 104 (e.g. non-AP STA l04b). If there is a negligible time-of- flight delay between the AP 102 and relevant non-AP STA(s) 104, then the communication 800 may be as seen at both the AP 102 and non-AP STA(s) 104. The communication 800 is the same as in communication 700, in that a DL 802 frame triggers an UL frame 808 based on generation data included in (and, optionally, before) the HE-SIG-B field. Like in communication 700, in the case of communication 800, there is a delay 806 between the time at which all of the generation data has been received and the time at which transmission of the UL frame 808 commences. The duration of the delay 806 is known by the AP 102, and is adjusted for in the DL frame 802 by extending the DL frame 802 by a frame synchronization portion 809. The frame synchronization portion 809 commences after the generation data (i.e. at the normal end of HE- SIG-B) and has a duration that matches the known delay 806. In other embodiments, one or both of the HE-STL and HE-LTL fields in the DL are of different from those in the UL. In such embodiments this difference can further contribute to a relative temporal displacement between uplink and downlink OLDM symbols in the respective uplink and downlink payloads. Therefore for such embodiments, the duration of the frame synchronization portion may be adjusted from the known delay 806 to also account for that further contribution to relative temporal displacement. The presence of the frame synchronization portion 809 extends suspends transmission of first OLDM symbols 811 of the DL frame 802 to be synchronized with second OLDM symbols 813 in the UL frame 808. The term“first” in the preceding sentence is not intended to imply that the transmission- suspended OLDM symbols 811 are necessary the first OLDM symbols to appear in the DL frame 802. Lor example, the HE-SIG- A and HE-SIG-B field are OLDM symbols, but precede the aforementioned“first OLDM symbols”. Likewise term “second” in that sentence is not intended to imply that the transmission- suspended OLDM symbols 813 are the second OLDM symbols to appear in the

UL frame 808. Lurther, while indicated OLDM 811, 813 symbols are shown as the data payload other field may also be synchronized. In the case of communication 800, the HE-LTL fields 819 are also synchronized and, in some embodiments of communication 800, HE-LSL fields 817 are also synchronized. The synchronization of the HE-LTL and, in some cases HE-STL, may be implemented regardless of whether HE-LTL and HE-STL are or are not OLDM symbols.

The duration of the known delay 806, and hence the duration of the frame synchronization portion, may be determined by the AP 102. Lor example, the delay 806 may be determined from a look-up table, stored in a memory component of AP 102, for the relevant non-AP STA 104. The look-up table may, for example, be based on known hardware behavior for a type of device (for example a specific model) of which the given non-AP STA 104 is a member. Alternatively, the delay 806 may derived from a previous communication or handshake procedure between the AP 102 and the relevant non-AP STA 104 that measures delay that includes not only processing delay, but also any other delay, such as time-of- flight delay.

In some embodiments, the frame synchronization portion 809 is an extension to the HE- SIG-B field 821 of the DL frame 802. In some other embodiments, the frame synchronization portion 809 is an extension to the HE-STF field 817 of the DL frame 802. In yet other embodiments, the frame synchronization portion 809 is an extension to the frame 802, in the form of a new field that is between the HE-SIG-B field 821 and the HE-STF field 817.

In some embodiments, the outbound frame 802 includes an indicator for identifying the frame synchronization portion 809. The indicator may, for example, be included in the frame synchronization portion 809. In some embodiments the indicator encodes a type of frame extension corresponding to the frame synchronization portion. For example, the indicator may encode a first value (e.g.‘ 1 O’) in an event that the frame synchronization portion is an extension to an HE-STF field; and a second value (e.g.‘0G) in an event that the frame synchronization portion is an extension to an HE-SIGB field. In some embodiments a third value (e.g.‘00’) may be used to provide further information, or may be reserved for future use.

Another way of implementing one or more aspects of the invention can be used for embodiments where a first frame in an STR communication is an UL frame, which leads to an STR DL frame. Some examples of such embodiments are included in FIGS. 9-11. For example, turning to the STR communication 900 in FIG. 9A, a UL frame 908 is transmitted by a non-AP STA, for example non-AP STA l04b. Generation data is included in the HE-SIGA field 910 of the uplink frame 908 and encodes frame format and, optionally, modulation and coding scheme data of UL frame 908. The frame format data includes preamble duration and frame duration information and guard interval duration and OFDM symbol duration information of the N OFDM symbols 918 of UL frame 908. The AP 102 decodes this data decides whether to transmit an STR DL frame, for example based on whether the AP 102 has allocated medium usage, at that time, to an STR DL transmission. Assuming a decision to provide an STR transmission is in the affirmative, the AP 102 transmits a DL STR frame 902 with a DL OFDM symbol format (symbol duration and cyclic prefix) matching the UL ODFM symbols. In some embodiments the OFDM symbol format is predefined, while in other embodiments it is flexible and drawn from the received generation data in the UL frame 908. Once all data necessary for generating a DL STR frame has been received by the AP 102, at time ti, for example, in some embodiments, at the end of the HE- SIGA field 910, the AP 102 transmits the DL frame 908 at time t₂. In some embodiments, the AP 102 transmits the DL frame 902 as soon as it can, but there is still a delay 906 between ti and t₂. Were the DL frame 902 to commence with a normal HE-STL field, which would have the same size as HE-STL field 911 ofthe UL frame 908, each OLDM symbols in the DL payload 920 would be unsynchronized with OLDM symbols in the UL payload 918. However, in the embodiment of STR communication 911 a first portion 912 of the DL frame 902 that precedes the DL OLDM symbols, and which in LIG. 9A includes the DL HE-STL field, has a start time and duration that causes a start of an initial OLDM symbol 914 of the DL OLDM symbols in the payload 920 into synchronization with an OLDM symbol 916 of the UL payload 918. Since each of the DL OLDM symbols have a format matching the UL OLDM symbols, the a plurality of DL OLDM symbols (from a I^st Data symbol to an N-l^th data symbol in communication 900) are synchronized with a plurality of UL OLDM symbols (from a 2^nd Data symbol to an N^th data symbol in communication 900). Additionally the HE-LTL field has the same duration as an OLDM data symbol so the HE-LTL field 918 in the DL frame 902 is synchronized with the I^st OLDM data symbol 919 in the UL frame 908. As shown in LIG. 9A there is an interval T, 922, between generation data (at time ti) and a start of a first of the UL OLDM symbols (at time t₃₎. The first portion 912 of the DL frame 902 is thus configured to act as a frame synchronization portion of the DL frame 902 that leads to the synchronization of the OLDM symbols, starting with symbols 914 and 916 as discussed above. The duration of the first portion/frame synchronization portion 912, is equal to the interval T, 922, minus the delay 906, and a start time at t_2, at the end of the delay 906. In the embodiment shown in LIG. 9A the frame synchronization portion 912 is an extended HE-STL field. Lor example it may be a normal HE- STL field with padded bits and/or additional information, such as information identifying that there is frame extension and, if there are various different frame extension that may be used, then it may also identify a type of frame extension.

LIG. 9B illustrates another exemplary STL communication 950 resulting in the same synchronization as depicted in LIG. 9A. The reference numerals in LIG. 9B that match reference numerals in FIG. 9A are intended to indicate corresponding elements in the communications 900, 950. In the case of communication 950, the frame synchronization portion 912' is a normal HE-STF field but the commencement of the synchronization portion 912' is configured to have a start time at t₄ that is delayed from the ordinary and earliest possible transmission time, t_2. In this case, the start time t₄ is equal to the time ti plus the time interval T, 922, minus the duration of the frame synchronization portion 912'. Considered another way the frame synchronization portion is delayed beyond t₂ by an amount which is equal to T, 922, minus the delay 906 minus the duration of the frame synchronization portion 912'. As will be appreciated, the frame synchronization portion may in other embodiments include some degree of extension to a normal HE-STF and some degree of delay beyond t₂.

In yet other embodiments, of which one example is illustrated in STR communication 1000 in FIG. 10, a speciaFnew STR preamble 1001 may be employed in the STR DL frame 1002 that commences in response to a leading UL frame 1008. The STR preamble may comprise the frame synchronization portion 912 or 912' of FIGS. 9A and 9B respectively also include the data in the HE-LTF field. In some embodiments the new STR preamble includes at least the same preamble information discussed in embodiments of FIGS. 9A and 9B (i.e. at least the information in HE-STF, HE-LTF), however the arrangement of information within the preamble may be different and/or may have a different duration. Further, additional data is in some cases added to the new preamble. One example of a specialized STR preamble is depicted in communication 1100 in FIG.

11. The STR preamble 1105 includes a frame synchronization portion 1112, which may for example have the same features as frame synchronization portion 912 (as is shown to be the case in FIG. 11) or frame synchronization portion 912'. The STR preamble 1105 also includes an HE-LTF field 1118. The STR preamble 1105 also includes an STR signal field 1120. The STR signal field 1120 has the same duration as an OFDM symbol, so though it further delays the start of the DL payload 1122, the OFDM symbols in the payload 1122 will nonetheless be synchronized with OFDM symbols in the UL frame 1108. In each of the embodiments of FIGS. 8 to 11, the second, STR frame 808, 902, 1002, 1102 being transmitted partway through a first/instigating frame 802, 908, 1008, 1108, omits the legacy WLAN portion (the legacy WiFi preamble comprised of STF, LTF and L-SIG) of the ordinary HE WLAN preamble. By having a shorter preamble, data transfer is more efficient. The legacy WLAN preamble is ordinarily included in WLAN transmissions because, amongst other reasons, it enables devices that receive the transmission to identify the transmission and act accordingly, e.g. by reserving medium access for the transmission. However, because the second frame is transmitted during a first WLAN frame, the medium is already reserved for the transmission, by virtue of the legacy WLAN preamble in the first frame. Thus the legacy WLAN preamble may be omitted from the start of the second frame. However, omitting the legacy WLAN preamble completely would result in some other useful information, such as the size of the frame second, being lost. Thus, in the embodiment in FIG. 11, the STR-SIG field 1120 can include, for example any or all of the information that could have otherwise been transmitted in HE-SIG-A. Though the specialized preamble is illustrated with respect to the second frame being a DL frame (e.g. FIGS. 9 to 11), the specialized preamble may additionally by used in the case of the second frame being a UL frame (e.g. FIG. 8).

FIGS. 12A to 12D illustrate flow charts of various methods in accordance with one or more embodiments of the invention.

Method 1200 of FIG 12A may for example correspond the embodiment shown in FIG. 8, from the perspective of an AP. At step 1202, the AP instructs transmission of an outbound

WFAN frame to a remote device, such as non-AP STA. The outbound frame includes a frame synchronization portion followed by first ODFM symbols and generation data for generating an inbound frame including second OFDM symbols, by the remote device. The frame synchronization portion suspends transmission of the first OFDM symbols to be synchronized with the second OFDM symbols by being generated to have a commencement after the generation data and a duration that is dependent on a known delay and a duration that is dependent on a known delay involved in communicating with the remote device. At step 1204, the AP receives the inbound WFAN frame from the remote device.

Method 1210 of FIG 12B may for example correspond the embodiment shown in FIG. 9A and/or FIG. 9B, from the perspective of an AP. At step 1212 the AP receives an inbound WFAN frame from a remote device such as a non-AP STA. The inbound frame includes second OFDM symbols and generation data for generating an outbound. At step 1214, the AP instructs transmission of the outbound WFAN frame to the remote device. The outbound frame includes a frame synchronization portion followed by first ODFM symbols. The frame synchronization portion suspends transmission of the first OFDM symbols to be synchronized with the second OFDM symbols by being generated to have at least one of a commencement time and a duration that is dependent on an interval between (i) the generation data and (ii) a start of an initial one of the second OFDM symbols.

Method 1220 of FIG 12C may for example correspond the embodiment shown in FIG. 8, from the perspective of a non-AP STA. At step 1222, receives an inbound WLAN frame from a remote device such as an AP. The inbound frame includes a frame synchronization portion followed by first ODFM symbols and generation data for generating an outbound frame including second OFDM symbols, by non-AP STA. The frame synchronization portion suspends reception of the first OFDM symbols to be synchronized with the second OFDM symbols by having a duration that is dependent on a known delay involved in communicating with non-AP STA. At step 1204, the non-AP STA instructs transmission of the outbound frame.

Method 1230 of FIG 12D may for example correspond the embodiment shown in FIG. 9A and/or FIG. 9B, from the perspective of a non-AP STA. At step 1232, the non-AP STA instructs transmission of an outbound frame including second OFDM symbols and generation data for generating an inbound frame, by a remote device, such as an AP. At step 1234, the non- AP STA receives the inbound WLAN frame from the remote device. The inbound frame includes a frame synchronization portion followed by first ODFM symbols. The frame synchronization portion suspends reception of the first OFDM symbols to be synchronized with the second OFDM symbols by having at least one of a commencement time and a duration that is dependent on an interval between (i) the instructions and (ii) a start of an initial one of the second OFDM symbols.

It is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the above description and/or illustrated in the drawings and/or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways. The present invention may be a system, a method, and/or a computer program product.

The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention.

Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions.

The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions.

Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims.

The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein. The terms "comprises", "comprising", "includes", "including",“having” and their conjugates mean "including but not limited to". This term encompasses the terms "consisting of' and "consisting essentially of'.

As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

The word“exemplary” is used herein to mean“serving as an example, instance or illustration”. Any embodiment described as“exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments.

The word“optionally” is used herein to mean“is provided in some embodiments and not provided in other embodiments”. Any particular embodiment of the invention may include a plurality of“optional” features unless such features conflict.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting.

Claims

WHAT IS CLAIMED IS:

1. A device (102) for network communication, comprising:

at least one processor (204) configured to:

instruct a transmission of an outbound Wireless Local Area Network, WLAN, frame (802, 902) to a remote device (104) via the network (100), the outbound frame including a frame synchronization portion (809, 809’ 912, 912’) followed by first Orthogonal Lrequency Division Multiplexing, ODLM, symbols; and

receive an inbound WLAN frame (808, 908) from the remote device, the inbound frame including second OLDM symbols,

wherein one of the transmitted outbound frame and the inbound frame includes generation data (821 , 910) for generating the other of the outbound frame, by the device, and the inbound frame, by the remote device; and

the frame synchronization portion suspends transmission of the first OLDM symbols to be synchronized with the second OLDM symbols by the frame synchronization portion being generated to have any one of:

in an event that the generation data is included in the outbound frame, a commencement after the generation data and a duration that is dependent on a known delay (806) involved in communicating with the remote device; and in an event that the generation data is included in the inbound frame, at least one of a commencement time and a duration that is dependent on an interval (922) between (i) the generation data and (ii) a start of an initial one of the second OLDM symbols. 2. The device according to claim 1, wherein in the event that the generation data is included in the outbound frame the known delay involved in communicating with the remote device comprises a processing time between the remote device receiving the generation data and transmitting said inbound frame; and

the at least one processor is further configured to determine said duration.

3. The device according to claim 2, wherein the known delay involved in communicating with the remote device also comprises a time of flight attributed to the inbound frame and a time of flight attributed to the inbound frame to the outbound frame.

4. The device according to any one of claims 2 to 3, wherein:

in the event that the generation data is included in the outbound frame, the frame synchronization portion comprises at least one of:

a lengthened portion of at least one of a signal field that includes the generation data; and

a lengthened portion of a training field that follows the generation data; and in the event that the generation data included in the inbound frame, the frame synchronization portion comprises an extended portion of a training field that is a first field of the outbound frame.

5. The device according to any one of claims 1 to 4, wherein in the event that the generation data is included in the outbound frame, the outbound frame includes an indicator for identifying the frame synchronization portion. 6. The device according to any one of claims 1 to 5, wherein transmission of the first

OFDM symbols and reception of the second OFDM symbols are synchronized at the device, to within a cyclic prefix that spaces the first OFDM symbols and spaces the second OFDM symbols. 7. The device according to any one of claims 1 to 6, wherein at least one of the OFDM symbols of said other of the outbound frame and the inbound frame encodes transmission parameters including one or more of:

modulation and coding scheme data; and

guard interval data.

8. The device according to any one of claims 1 to 7, wherein the generation data encodes one or more of the following parameters that correspond to the OFDM symbols of said one of the transmitted outbound frame and the inbound frame:

modulation and coding scheme data; and

guard interval data.

9. The device according to any one of claims 1 to 8, wherein the device is an access point of a wireless local area network.

10. A device (104) for network communication, the device comprising: at least one processor (204) configured to:

receive an inbound Wireless Local Area Network, WLAN, frame (802, 902) from a remote device (102) via the network (100), the inbound frame including a frame synchronization portion (809, 809’ 912, 912’) followed by first Orthogonal Frequency Division

Multiplexing, ODFM, symbols; and

instruct transmission of an outbound frame (808, 908), the outbound frame including second OFDM symbols;

wherein one of the transmitted outbound frame and the inbound frame includes generation data (821, 910) for generating the other of the outbound frame, by the device, and the inbound frame, by the remote device; and

wherein the frame synchronization portion suspends reception of the first OFDM symbols to be synchronized with the second OFDM symbols by having any one of:

in an event that the generation data is included in the inbound frame, a commencement after the generation data and a duration that is dependent on a known delay (806) involved in communicating with the device; and

in an event that the generation data is included in the outbound frame, at least one of a commencement time and a duration that is dependent on an interval (922) between (i) the generation data and (ii) a start of an initial one of the second OFDM symbols.

11. A method for network communicating, the method comprising, at a first device

(102):

instructing transmission of an outbound Wireless Local Area Network, WLAN, frame (802, 902) to a remote device (104), the outbound frame including a frame synchronization portion (809, 809’ 912, 912’) followed by first Orthogonal Frequency Division Multiplexing, ODFM, symbols; and

receiving an inbound WLAN frame (808, 908) from the remote device, the inbound frame including second OFDM symbols,

wherein one of the outbound frame and the inbound frame includes generation data

(821, 910) for generating the other of the outbound frame, by the first device, and the inbound frame, by the remote device; and the frame synchronization portion suspends transmission of the first OFDM symbols to be synchronized with the second OFDM symbols by being generated to have any one of:

in an event that the generation data is included in the outbound frame, a commencement after the generation data and a duration that is dependent on a known delay (806) involved in communicating with the remote device; and in an event that the generation data is included in the inbound frame, at least one of a commencement time and a duration that is dependent on an interval (922) between (i) the generation data and (ii) a start of an initial one of the second OFDM symbols.

12. The method according to claim 11, wherein in the event that the generation data is included in the outbound frame the known delay involved in communicating with the remote device comprises a processing time between the remote device receiving the generation data and transmitting said inbound frame; and

the method further comprises determining said duration.

13. The method according to claims 11 or 12, wherein the first OFDM symbols of the outbound frame and reception of the second OFDM symbols of the inbound frame are synchronized at the first device, to within a cyclic prefix that spaces the first OFDM symbols and spaces the second OFDM symbols.

14. A method for network communicating, the method comprising, at a first device

(104):

receiving an inbound (802, 902) Wireless Local Area Network, WLAN, frame from a remote device (102) via the network (100), the inbound frame including a frame synchronization portion (809, 809’ 912, 912’) followed by first Orthogonal Frequency Division Multiplexing, ODFM, symbols;

instructing transmission of an outbound frame (808, 908), the outbound frame including second OFDM symbols;

wherein one of the transmitted outbound frame and the inbound frame includes generation data (821, 910) for generating the other of the outbound frame, by the device, and the inbound frame, by the remote device; and wherein the frame synchronization portion suspends reception of the first OFDM symbols to be synchronized with the second OFDM symbols by having any one of:

in an event that the generation data is included in the outbound frame, at least one of a commencement time and a duration that is dependent on an interval (922) between (i) the instructions and (ii) a start of an initial one of the second OFDM symbols.

15. A computer program with a program code for performing a method according to any of claims 11 to 14, when the computer program runs on a computer.