Patent Description:
Next generation Wireless Local Area Networks (WLANs) will be deployed in high-density environments that include multiple access points providing wireless access to large numbers of mobile stations in the same geographical area. Next-generation WLANs will also need to simultaneously support various traffic types having diverse quality of service (QoS) requirements, as mobile devices are increasingly used to access streaming video, mobile gaming, and other services. Institute of Electrical and Electronics Engineers (IEEE) <NUM>. 11ax is being developed to address these challenges, and is expected to provide up to four times the throughput of IEEE <NUM>. 11ac networks.

<CIT> discloses embodiments of a wireless device and method for transmitting a packet comprising one or more orthogonal frequency division multiplexed (OFDM) transmission symbols. <CIT> discloses systems and methods for using travelling pilots for channel estimation.

Technical advantages are generally achieved, by embodiments of this disclosure which describe system and method for OFDMA resource allocation. Embodiments labelled as inventive embodiments in the following, which are not covered by the scope of protection defined by the independent claims, are to be understood as examples helpful for understanding the invention, but not as embodiments of the invention.

In accordance with an embodiment, a method for transmitting data in a wireless network is provided. In this example, the method includes generating an orthogonal frequency division multiple access (OFDMA) frame that includes a <NUM> tone payload consisting of <NUM> tones carried in one or more resource units (RUs) and <NUM> tones excluded from the one or more RUs. The <NUM> tones excluded from the one or more RUs include common pilot tones, null tones, reserved tones, or combinations thereof. The method further includes transmitting the generated OFDMA frame to at least one receiver over a <NUM> megahertz (MHz) frequency channel. An apparatus for performing this method is also provided.

In accordance with another embodiment, a method for communicating scheduling information in a wireless network is provided. In this example, the method comprises transmitting an orthogonal frequency division multiple access (OFDMA) frame carrying a signal (SIG) field and a sequence of resource units (RUs). A subset of RUs in the OFDMA frame are allocated to one or more stations (STAs). Index information embedded in the SIG field associates an identifier (ID) assigned to the one or more STAs with a starting or ending position of the subset of RUs in the sequence of RUs carried by the OFDMA frame. An apparatus for performing this method is also provided.

In accordance with another embodiment, a method for communicating data in a wirless network is provided. In this example, the method comprises transmitting an orthogonal frequency division multiple access (OFDMA) frame to at least one receiver. The OFDMA frame includes a resource unit (RU) consisting of either a multiple of <NUM> tones or a multiple of <NUM> tones. An apparatus for performing this method is also provided.

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:.

The structure, manufacture and use of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.

Aspects of this disclosure provide embodiment frame formats for use in a wireless environment such as an IEEE <NUM>. 11ax network. More specifically, the embodiment frame formats specify that an OFDMA frame carries a <NUM>-tone payload consisting of <NUM> tones carried in one or more resource units (RUs) and <NUM> tones excluded from the one or more RUs. The <NUM> tones excluded from the RUs may include common pilot tones, null tones, reserved tones, or combinations thereof. In one example, the <NUM> tones excluded from the RUs consist of <NUM> common pilot tones and <NUM> null tones. In another example, the <NUM> tones excluded from the RUs consist of <NUM> reserved tones and <NUM> null tones. Guard tones are positioned in-between RUs to mitigate interference, while DC tones are empty subcarriers (e.g., subcarriers that do not carry data/information) that are used by mobile devices to locate the center of an OFDM frequency band. In one embodiment, the <NUM> tones excluded from RUs of the OFDMA frame consist of <NUM> common pilots and <NUM> null tones. In another embodiment, the <NUM> tones excluded from RUs of the OFDMA frame consist of <NUM> reserved tones and <NUM> null tones. Reserved tones are tones that are excluded from the RUs, but are not officially designated as null tones or pilot tones. Reserved tones may be used for any purpose. Notably, RUs in an OFDMA frame may generally carry data tones, which are tones that transport payload data. In one embodiment, each RU in an OFDMA frame consists of a multiple of <NUM> data tones (e.g., <NUM> data tones, <NUM> data tones, <NUM> data tones, etc.). Additionally, RUs in an OFDMA frame may also carry separate pilot tones. In one embodiment, each RU in an OFDMA carries a multiple of <NUM> tones, with each multiple consisting of <NUM> pilot tones and <NUM> data tones. The separate pilot tones carried in an RU may be used to adjust or estimate phase and/or frequency parameters of data tones carried in the RU. For example, in an uplink OFDMA frame carrying RUs transmitted by different mobile devices, the pilot tones carried in the respective RUs may be used by a serving access point to perform residual carrier frequency offset estimation on the uplink OFDMA frame. Residual frequency offset compensation may include estimating a carrier frequency offset based on dedicated pilots carried in OFDMA transmissions. For uplink (UL) OFDMA transmissions, residual carrier frequency offset compensation may allow the access point to track a phase of each symbol based on pilots carried in resource units (RUs).

Embodiments of this disclosure further provide symbol based RU tone allocation schemes in which an RU carried in an OFDMA frame consists of a multiple of either <NUM> or <NUM> tones. In one embodiment, the RU consists of a multiple of <NUM> tones, with each multiple of <NUM> tones consisting of <NUM> data tones and <NUM> pilot tones. In another embodiment, the RU consists of a multiple of <NUM> tones, with each multiple of <NUM> tones consisting of <NUM> data tones and <NUM> pilot tones.

Aspects of this disclosure also provide an embodiment technique for communicating RU allocations to mobile devices receiving an OFDMA frame. More specifically, index information is embedded in a signal (SIG) field of an OFDMA frame. The index information associates IDs assigned to individual stations, or groups of stations, with starting or ending positions for subsets of assigned RUs in a sequence of RUs carried by the OFDMA frame. For example, the indexing information may indicate a leading RU and/or trailing RU in a subset of RUs allocated to a station, and may allow the station to locate the subset of allocated RUs upon receiving the frame. These and other details are described in greater detail below.

<FIG> illustrates a wireless network <NUM> for communicating data. The wireless network <NUM> includes an access point (AP) <NUM> which has a coverage area <NUM>, a plurality of mobile devices <NUM>, and a backhaul network <NUM>. The AP <NUM> may comprise any component capable of providing wireless access by, among other things, establishing uplink (dashed line) and/or downlink (dotted line) connections with the mobile devices <NUM>. For instance, the AP <NUM> may be a base station, an enhanced base station (eNB), a femtocell, a Wi-Fi AP, and other devices capable of providing wireless access to the mobile devices <NUM>. The mobile devices <NUM> may comprise any component capable of establishing a wireless connection with the AP <NUM>, such as a mobile station (STA), a user equipment (UE), or other wirelessly enabled devices. The backhaul network <NUM> may be any component or collection of components that allow data to be exchanged between the AP <NUM> and a remote end. In some embodiments, there may be multiple such networks, and/or the network may comprise various other wireless devices, such as relays, low power nodes, etc..

<FIG> is a diagram of an embodiment tone allocation scheme for a <NUM>-tone payload <NUM> in an OFDMA frame communicated over a <NUM> frequency channel. As shown, the <NUM>-tone payload <NUM> includes two-hundred and thirty-four tones carried in RUs <NUM>, and twenty-two tones <NUM> excluded from the RUs <NUM>. The twenty-two tones <NUM> excluded from the RUs <NUM> may include null tones, pilot tones, reserved tones, or combinations thereof. Each of the RUs <NUM> carried in the <NUM>-tone payload <NUM> consists of a multiple of <NUM> tones. In the example provided by <FIG>, the two-hundred and thirty-four tones are distributed into nine RUs <NUM> such that each of the RUs consists of <NUM> tones (i.e., one multiple of <NUM> tones). However, it should be appreciated that the two-hundred and thirty-four tones may be distributed into fewer RUs. For example, the two-hundred and thirty-four tones may be distributed into three <NUM>-tone RUs. It should also be appreciated that the two-hundred and thirty-four tones is unevenly distributed into the RUs <NUM> such that at least two RUs in the <NUM>-tone payload <NUM> are different sizes. In one example, the two-hundred and thirty-four tones are distributed into four <NUM>-tone RUs and one <NUM>-tone RU. In another example, the two-hundred and thirty-four tones are distributed into two <NUM>-tone RUs and one <NUM>-tone RU. In yet another example, all of the two-hundred and thirty-four tones are distributed into a single RU. It should also be appreciated that the twenty-two tones <NUM> excluded from the RUs <NUM> may be arranged in any location, or set of locations, within the <NUM>-tone payload <NUM>. For example, each of the twenty-two tones <NUM> could be positioned in a contiguous portion of the <NUM>-tone payload <NUM>, e.g., in the center, top, or bottom portion of the <NUM>-tone payload. As another example, the twenty-two tones <NUM> could be distributed evenly, or unevenly, across the <NUM>-tone payload <NUM>, e.g., in-between the RUs <NUM>, etc..

<FIG> illustrates a diagram of an embodiment tone allocation scheme for an OFDMA resource unit (RU) <NUM>. As shown, the RU <NUM> consists of a multiple of <NUM> tones (N*<NUM>-tones) in the frequency domain (where N ≥ <NUM>). The RU <NUM> may span any number of symbols (M symbols) in the time domain (where M ≥ <NUM>). In one example, the RU <NUM> spans <NUM> symbols in the time-domain. In some embodiments, each multiple of <NUM> tones in the RU <NUM> consists entirely of data tones. In other embodiments, each multiple of <NUM> tones in the RU <NUM> consists of both pilot and data tones, e.g., one pilot and <NUM> data tones, two pilots and <NUM> data tones, etc. In such embodiments, the pilot tones may be used for phase tracking.

<FIG> illustrates a diagram of an embodiment tone allocation scheme for a <NUM>-tone payload <NUM> in an OFDMA frame communicated over a <NUM> frequency channel. As shown, the <NUM>-tone payload <NUM> includes two-hundred and thirty-four tones carried in RUs <NUM>, <NUM> common pilot tones <NUM>, and <NUM> null tones <NUM>. The common pilot tones <NUM> and the null tones <NUM> are excluded from the RUs <NUM>. In one example, the <NUM> null tones <NUM> consist of <NUM> guard tones and <NUM> DC tone. In other examples, the <NUM> null tones <NUM> include multiple DC tones and <NUM> or fewer guard tones. Each of the RUs <NUM> consists of a multiple of <NUM> data tones. In one embodiment, the <NUM>-tone payload <NUM> is carried in a downlink OFDMA frame.

<FIG> illustrates a diagram of another embodiment tone allocation scheme for a <NUM>-tone payload <NUM> in an uplink OFDMA frame communicated over a <NUM> frequency channel. As shown, the <NUM>-tone payload <NUM> includes two-hundred and thirty-four tones carried in RUs <NUM>, <NUM> reserved tones <NUM>, and <NUM> null tones <NUM>. The reserved tones <NUM> and the null tones <NUM> are excluded from the RUs <NUM>. In one example, the <NUM> null tones <NUM> consist of <NUM> guard tones and <NUM> DC tone. In other examples, the <NUM> null tones <NUM> consist of multiple DC tones and fewer than <NUM> guard tones, e.g., <NUM> DC tones + <NUM> guard tones, <NUM> DC tones + <NUM> guard tones, etc. Each of the RUs <NUM> consists of a multiple of <NUM> tones, with each multiple of <NUM> tones consisting pilot tones and data tones. In the example configuration depicted by <FIG>, each multiple of <NUM> tones in a given one of the RUs <NUM> consists of two pilot tones and twenty-four data tones (<NUM> pilots + <NUM> data tones). It should be appreciated that other configurations are also possible, e.g., <NUM> pilot + <NUM> data tones, <NUM> pilots + <NUM> data tones, etc. In the example configuration depicted by <FIG>, the <NUM> reserved tones <NUM> are evenly distributed over the <NUM>-tone payload <NUM>. In such an example, the reserved tones <NUM> may serve as guard bands between RUs in the uplink OFDMA frame. It should be appreciated that the <NUM> reserved tones <NUM> may be distributed differently (e.g., unevenly) in the <NUM>-tone payload <NUM>, and that two or more of the reserved tones <NUM> may be positioned in a contiguous portion of the <NUM>-tone payload <NUM>. It should also be appreciated that the reserved tones <NUM> may be used for other purposes. In one embodiment, the <NUM>-tone payload <NUM> is carried in an uplink OFDMA frame.

<FIG> illustrates simulation results of spectrum efficiency for different size resource units (RUs). The simulation was performed to evaluate how spectrum efficiency was affected by the size of resource units carried in OFDMA frames communicated over different IEEE <NUM> non-line-of-sight (NLOS) channel models. In this example, the simulation was performed over IEEE <NUM> B, C, D, E, and F NLOS channel conditions, which have varying rms delay spreads. As shown, the spectrum efficiency begins to be substantially reduced for all channel conditions as the RU is increased from <NUM>^<NUM> to <NUM>^<NUM>.

<FIG> illustrates a block diagram of an embodiment RUs indexing scheme <NUM>. As shown, the RUs indexing scheme <NUM> comprises a group of subcarriers <NUM>, <NUM>, <NUM>, <NUM> in the time domain (e.g., OFDMA symbol) and the frequency domain (e.g., subcarrier). More specifically, each of the group of subcarriers <NUM>, <NUM>, <NUM>, <NUM> comprises a set of RUs having index information that includes a sequence number associated with the set of RUs in the time domain. The number of RUs that are embedded in an OFDMA frame depends on the number of OFDMA symbols (k) and the number of subcarriers (n). In an embodiment, an index number is sequentially allocated to RUs that are located in different groups of subcarriers. For example, an index number is sequentially allocated to the last RU (e.g., RU4j) in the group of subcarriers <NUM> from the first RU (e.g., RU<NUM>) in the group of subcarriers <NUM>. In another embodiment, an index number is sequentially allocated to RUs that are located in the same group of subcarriers. For example, an index number is sequentially allocated to the RUj from the RU<NUM> in the same group of subcarriers <NUM>.

<FIG> illustrates a diagram of an embodiment RU allocation scheme <NUM>. As shown, the RU allocation scheme <NUM> allocates portions of subcarrier groups (SCGs) <NUM>, <NUM>, <NUM>, <NUM> to a plurality of users. Different sets of RUs in the SCG <NUM> are allocated to a first user (user-<NUM>) and a second user (user-<NUM>). All RUs in the SCG <NUM> are allocated to a third user (user-<NUM>). Different sets of RUs in the SCG <NUM> are allocated to a fourth user (user-<NUM>) and a fifth user (user-<NUM>), while some RUs in the SCG <NUM> carry padding bits (e.g., null RUs) that are not allocated to any users. All RUs in the SCG <NUM> are allocated to a sixth user (user-<NUM>). Specifically, sets of RUs that are located in different SCGs are not allocated to the same user. In some embodiments, individual users may be allocated any number of RUs in a subcarrier group. For instance, in the example depicted by <FIG>, all RUs in the SCH <NUM> are allocated to a single user (i.e., user <NUM>). In other embodiment, allocation schemes may restrict the number of RUs that can be allocated to an individual user. In one embodiment, an allocation scheme mandates that no more than two RUs are allocated to an individual user.

<FIG> illustrates a diagram of index information <NUM> for embedding in a signal (SIG) field of an OFDM frame. As shown, the scheduling information <NUM> comprises an identifier (ID) field <NUM>, an RU start index <NUM>, and an RU end index <NUM>. The ID field <NUM> may specify an ID assigned to an individual station (e.g., a PAID) or an ID assigned to a group of stations (e.g., a Group ID (GrpID). The RU start index <NUM> may specify a starting location (e.g., a leading RU) in a set of RUs allocated to the station or group of stations identified by the ID field <NUM>. The RU start index <NUM> may specify an ending location (e.g., a trailing RU) in a set of RUs allocated to the station or group of stations may include two or more RUs. A leading RU in the set of RUs may precede (e.g., be positioned in front of) all others RUs in the set of RUs. Likewise, a trailing RU in the set of RUs may follow (e.g., be positioned after) all other RUs in the set of RUs.

<FIG> illustrates a flow chart of an embodiment method <NUM> for transmitting RUs. As shown, the method <NUM> begins at step <NUM>, where a transmitter generates an OFDMA frame including a <NUM>-tone payload that consists of two-hundred and thirty-four tones carried in one or more resource units (RUs), and <NUM> tones excluded from the one or more RUs. The <NUM> tones excluded from the one or more RUs may consist of <NUM> common pilot tones and <NUM> null tones or of <NUM> reserved tones and <NUM> null tones. The <NUM> null tones may consist of guard tones and at least one direct current (DC) tone. In one embodiment, the OFDMA frame is a downlink OFDMA frame, and the <NUM>-tone payload includes <NUM> pilot tones, <NUM> null tones, and one or more RUs each of which including an integer multiple of <NUM> subcarriers. In such an embodiment, the integer multiple of <NUM> subcarriers include either an integer multiple of <NUM> data tones or an integer multiple of <NUM> data tones and <NUM> pilot tones carrying data to one or more STAs. In another embodiment, the OFDMA frame is an uplink OFDMA frame, and the <NUM>-tone payload includes <NUM> reserved tones, <NUM> null tones, and one or more RUs each of which including an integer multiple of <NUM> subcarriers. In such an embodiment, the integer multiple of <NUM> subcarriers include an integer multiple of <NUM> data tones and <NUM> pilot tones carrying data to one or more STAs. Subsequently, the method <NUM> proceeds to step <NUM>, where the transmitter transmits the OFDMA frame including the one or more RUs to at least one receiver.

In one embodiment, a resource unit (RU) consists of a multiple of <NUM> tones, with each multiple of <NUM> tones consisting of <NUM> pilot tones and <NUM> data tones. For example, the RU may consist of <NUM> pilot tones and <NUM> data tones; <NUM> pilot tones and <NUM> data tones; <NUM> pilot tones and <NUM> data tones; <NUM> pilot tones and <NUM> data tones; or <NUM> pilot tones and <NUM> data tones. In another embodiment, a RU consists of a multiple of <NUM> tones, with each multiple of <NUM> tones consisting of <NUM> pilot tones and <NUM> data tones. For example, the RU may consist of <NUM> pilot tones and <NUM> data tones; <NUM> pilot tones and <NUM> data tones; <NUM> pilot tones and <NUM> data tones; <NUM> pilot tones and <NUM> data tones; or <NUM> pilot tones and <NUM> data tones. Other combinations are also possible.

<FIG> illustrates a block diagram of an embodiment processing system <NUM> for performing methods described herein, which may be installed in a host device. As shown, the processing system <NUM> includes a processor <NUM>, a memory <NUM>, and interfaces <NUM>-<NUM>, which may (or may not) be arranged as shown in <FIG>. The processor <NUM> may be any component or collection of components adapted to perform computations and/or other processing related tasks, and the memory <NUM> may be any component or collection of components adapted to store programming and/or instructions for execution by the processor <NUM>. In an embodiment, the memory <NUM> includes a non-transitory computer readable medium. The interfaces <NUM>, <NUM>, <NUM> may be any component or collection of components that allow the processing system <NUM> to communicate with other devices/components and/or a user. For example, one or more of the interfaces <NUM>, <NUM>, <NUM> may be adapted to communicate data, control, or management messages from the processor <NUM> to applications installed on the host device and/or a remote device. As another example, one or more of the interfaces <NUM>, <NUM>, <NUM> may be adapted to allow a user or user device (e.g., personal computer (PC), etc.) to interact/communicate with the processing system <NUM>. The processing system <NUM> may include additional components not depicted in <FIG>, such as long term storage (e.g., non-volatile memory, etc.).

In some embodiments, the processing system <NUM> is included in a network device that is accessing, or part otherwise of, a telecommunications network. In one example, the processing system <NUM> is in a network-side device in a wireless or wireline telecommunications network, such as a base station, a relay station, a scheduler, a controller, a gateway, a router, an applications server, or any other device in the telecommunications network. In other embodiments, the processing system <NUM> is in a user-side device accessing a wireless or wireline telecommunications network, such as a mobile station, a user equipment (UE), a personal computer (PC), a tablet, a wearable communications device (e.g., a smartwatch, etc.), or any other device adapted to access a telecommunications network.

In some embodiments, one or more of the interfaces <NUM>, <NUM>, <NUM> connects the processing system <NUM> to a transceiver adapted to transmit and receive signaling over the telecommunications network. <FIG> illustrates a block diagram of a transceiver <NUM> adapted to transmit and receive signaling over a telecommunications network. The transceiver <NUM> may be installed in a host device. As shown, the transceiver <NUM> comprises a network-side interface <NUM>, a coupler <NUM>, a transmitter <NUM>, a receiver <NUM>, a signal processor <NUM>, and a device-side interface <NUM>. The network-side interface <NUM> may include any component or collection of components adapted to transmit or receive signaling over a wireless or wireline telecommunications network. The coupler <NUM> may include any component or collection of components adapted to facilitate bi-directional communication over the network-side interface <NUM>. The transmitter <NUM> may include any component or collection of components (e.g., up-converter, power amplifier, etc.) adapted to convert a baseband signal into a modulated carrier signal suitable for transmission over the network-side interface <NUM>. The receiver <NUM> may include any component or collection of components (e.g., down-converter, low noise amplifier, etc.) adapted to convert a carrier signal received over the network-side interface <NUM> into a baseband signal. The signal processor <NUM> may include any component or collection of components adapted to convert a baseband signal into a data signal suitable for communication over the device-side interface(s) <NUM>, or vice-versa. The device-side interface(s) <NUM> may include any component or collection of components adapted to communicate data-signals between the signal processor <NUM> and components within the host device (e.g., the processing system <NUM>, local area network (LAN) ports, etc.).

Claim 1:
A wireless apparatus, comprising:
a processor (<NUM>); and
a non-transitory computer readable storage medium (<NUM>) storing programming for execution by the processor, the programming, when executed by the processor, instructing the wireless apparatus to:
communicate an orthogonal frequency division multiple access, OFDMA, frame over a <NUM> megahertz, MHz frequency channel,
wherein the OFDMA frame including a <NUM> tones (<NUM>, <NUM>, <NUM>) consisting of <NUM> tones carried in a plurality of resource units, RUs (<NUM>, <NUM>, <NUM>), and <NUM> tones (<NUM>, <NUM>, <NUM>, <NUM>,<NUM>) excluded from the plurality of RUs;
wherein the plurality of RUs comprises <NUM> first RUs, or at least one first RU and at least one second RU, wherein each of the at least one first RU consists of <NUM> data tones and <NUM> pilot tones, each of the at least one second RU consists of <NUM> data tones and <NUM> pilot tones.