System and method for communicating an orthogonal frequency division multiplexed (OFDM) frame format

An Orthogonal Frequency Division Multiple Access (OFDMA) frame communicated over a 20 MegaHertz (MHz) channel may include eight 26-tone resource units (RUs), one 26-tone bifurcated RU, and a direct current (DC) region. The eight 26-tone RUs may include twenty-six consecutive data and pilot tones, and the bifurcated 26-tone RU may be split into two 13-tone portions each of which include thirteen consecutive data and pilot tones. The DC region may include seven null tones. In one example, the DC region of the 20 MHz MU-OFDMA frame consists of three DC tones and four null-data tones.

TECHNICAL FIELD

The present invention relates to a system and method for wireless communications, and, in particular, to a system and method for communicating an orthogonal frequency division multiplexing (OFDM) frame format.

BACKGROUND

Next generation Wireless Local Area Networks (WLANs) will be deployed in high-density environments that include access points (APs) providing wireless access to large numbers of stations (STAs) in the same geographical area. It is desirable for next generation WLANs to simultaneously support various traffic types having diverse quality of service (QoS) requirements, because mobile devices are increasingly used to access streaming video, mobile gaming, and other services.

SUMMARY OF THE INVENTION

Technical advantages are generally achieved, by embodiments of this disclosure which describe a system and method for communicating an orthogonal frequency division multiplexing (OFDM) frame format.

In accordance with an embodiment, a method for communicating data is provided. In this example, the method includes transmitting an orthogonal frequency division multiple access (OFDMA) frame. The OFDMA frame includes a first set of data and pilot tones, a second set of data and pilot tones, and a direct current (DC) region positioned between the first set of data and pilot tones and the second set of data and pilot tones. The DC region consisting of seven null tones that exclude data and pilot signaling. An apparatus for performing this method is also provided.

In accordance with another embodiment, another method for communicating data is provided. In this example, the method includes receiving an orthogonal frequency division multiple access (OFDMA) frame. The OFDMA frame includes a first set of data and pilot tones, a second set of data and pilot tones, and a direct current (DC) region positioned between the first set of data and pilot tones and the second set of data and pilot tones. The DC region consisting of seven null tones that exclude data and pilot signaling. The method further includes decoding at least a portion of the OFDMA frame. An apparatus for performing this method is also provided.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Institute of Electrical and Electronics Engineers (IEEE) 802.11ac defines a WLAN protocol for communicating data over 2.5 GigaHertz (GHz) and 5 GHz carrier frequencies, and may be capable of supporting aggregate throughput rates of up to 6.77 Gigabits per second (Gits/s). Even higher throughput rates may be needed to satisfy the performance goals of next-generation WLANs. As a result, IEEE 802.11ax is being developed as an extension to IEEE 802.11ac with a goal of providing up to 10 GBits over the 2.4 GHz and 5 GHz carrier frequencies.

Embodiment tone plans for communicating Orthogonal Frequency Division Multiple Access (OFDMA) frames over 20 Megahertz (MHz), 40 MHz, and 80 MHz channels are provided herein. One or more of the embodiment tone plans may be adopted by IEEE 802.11ax. In one embodiment, a Multi-User OFDMA (MU-OFDMA) frame is communicated over a 20 MHz channel. A MU-OFDMA frame may carry multiple data streams in different resource units (RUs) to one or more receiving devices. The 20 MHz MU-OFDMA frame may include eight 26-tone resource units (RUs), one 26-tone bifurcated RU, and a direct current (DC) region. The eight 26-tone RUs include twenty-six consecutive data and pilot tones, and the bifurcated 26-tone RU is split into two 13-tone portions each of which include thirteen consecutive data and pilot tones. The DC region may include seven null tones. In one example, the DC region of the 20 MHz MU-OFDMA frame consists of three DC tones and four null-data tones. Null tones are tones that exclude data, pilot, and control signaling, such as DC tones, guard tones, and/or null-data tones (e.g., data tones that have been re-purposed as null tones). Null tones may be positioned in-between adjacent RUs in an OFDMA frame to mitigate inter-symbol interference in-between the respective data streams carried by the adjacent RUs. Null tones may also be positioned in-between adjacent carriers (e.g., in an edge region) to mitigate inter-carrier interference and to protect RUs near the edge region from distortion due to transmission filtering and other effects. The eight 26-tone RUs, as well as the respective 13-tone portions of the bifurcated RU, are be distributed over two data and pilot regions, and the DC region is positioned in-between those data and pilot regions. In particular, four of the 26-tone RUs and one 13-tone portion of the bifurcated RU may be positioned in one data and pilot region; and the remaining four 26-tone RUs, as well as the other 13-tone portion of the bifurcated RU, may be positioned in the other data and pilot region. Each of the data and pilot regions may be positioned in-between the DC region and a corresponding edge region. One of the edge regions may include a pair of null-data tones and six guard tones. The other edge region may include a pair of null-data tones and five guard tones.

In another embodiment, a MU-OFDMA frame is communicated over an 80 MHz channel. The 80 MHz MU-OFDMA frame includes thirty-six 26-tone RUs, one 26-tone bifurcated RU, and a DC region consisting of seven DC tones. The RUs may be distributed over two inner-most data and pilot regions and two outer-most data and pilot regions. In one example, nine of the 26-tone RUs and one 13-tone portion of the bifurcated RU are positioned in each of the inner-most data and pilot regions; and nine of the 26-tone RUs are positioned in each of the outer-most data and pilot regions. The DC region may be positioned in-between the inner-most data and pilot regions, and each one of the outer-most data and pilot regions may be positioned in-between a respective one of the inner-most data and pilot regions and a corresponding edge region. One of the edge regions may include a set of eight null-data tones and twelve guard tones. The other edge region may include a set of eight null-data tones and eleven guard tones. In some embodiments, a set of eight null-data tones is positioned in-between each inner-most data region and the corresponding outer-most data and pilot region. In such embodiments, the 80 MHz MU-OFDMA frame may carry thirty-six null-data tones.

In another embodiment, a Single User OFDMA (SU-OFDMA) frame is communicated over an 80 MHz channel. A SU-OFDMA frame may carry a single data stream to a receiving device. In one example, the 80 MHz SU-OFDMA frame includes 994 data and pilot tones, a 26-tone bifurcated RU, and seven DC tones. The 994 data and pilot tones are distributed over two inner-most data and pilot regions and two outer-most data and pilot regions. The two inner-most data and pilot regions each carry 242 consecutive data and pilot tones and one 13-tone portion of the bifurcated RU. The two outer-most data and pilot regions each carry 242 consecutive data and pilot tones. Similar to the 80 MHz MU-OFDMA frame, the DC region in the 80 MHz SU-OFDMA frame may be positioned in-between the inner-most data and pilot regions. Each one of the outer-most data and pilot regions in the 80 MHz SU-OFDMA frame may be positioned in-between a respective one of the inner-most data and pilot regions and a corresponding edge region. One of the edge regions may include twelve guard tones, and the other edge region includes eleven guard tones. These and other aspects are described in greater detail below.

FIG. 1illustrates a network100for communicating data. The network100comprises an access point (AP)110having a coverage area101, a plurality of mobile stations120, and a backhaul network130. As shown, the AP110establishes uplink (dashed line) and/or downlink (dotted line) connections with the mobile stations120, which serve to carry data from the mobile stations120to the AP110and vice-versa. Data carried over the uplink/downlink connections may include data communicated between the mobile stations120, as well as data communicated to/from a remote-end (not shown) by way of the backhaul network130. As used herein, the term “access point (AP)” refers to any component (or collection of components) configured to provide wireless access to a network, such as an enhanced base station (eNB), a macro-cell, a femtocell, a Wi-Fi access point (AP), or other wirelessly enabled devices. APs may provide wireless access in accordance with one or more wireless communication protocols, e.g., Wi-Fi 802.11a/b/g/n/ac/ax, long term evolution (LTE), LTE advanced (LTE-A), High Speed Packet Access (HSPA), etc. As used herein, the term “mobile station” refers to any component (or collection of components) capable of establishing a wireless connection with an AP, such as a station (STA), a user equipment (UE), and other wirelessly enabled devices. In some embodiments, the network100may comprise various other wireless devices, such as relays, low power nodes, etc.

FIG. 2is a diagram of an embodiment frame structure for a downlink (DL) OFDM frame200. As shown, the downlink OFDM frame200includes a legacy short training field (L-STF)/long training field (LTF)201, a legacy signaling field (L-SIG)/repeated legacy (RL) SIG field202, a high efficiency (HE) first signal (SIGA) field204, a HE second signal (SIGB) field206, a HE-STF/LTF field208, and a data payload field210. Scheduling index information is embedded in the SIGB field206. The index information associates identifiers (IDs) assigned to individual STAs or groups of STAs, with starting or ending positions for subsets of assigned RUs in a sequence of RUs carried by the OFDM frame. For example, the scheduling index information may indicate a leading RU and/or trailing RU in a subset of RUs allocated to a STA, and may enable the STA to locate the subset of allocated RUs upon receiving the frame.

FIG. 3Ais a diagram of an embodiment tone plan for a MU-OFDMA frame301that is communicated over a 20 MHz channel. As shown, the MU-OFDMA frame301includes eight 26-tone RUs310, two portions311,312of a bifurcated 26-tone RU, null-data tones320, and DC tones330. In this example, three DC tones330and four null-data tones320are included in a DC region350. Four of the 26-tone RUs310and one portion311of the bifurcated RU are included in the data and pilot region381, and four of the 26-tone RUs310and the remaining portion312of the bifurcated RU are included in the data and pilot region382. The DC region350is positioned in-between the data and pilot region381and the data and pilot region382. Two of the null-data tones320are included in an edge region391and two of the null-data tones320are positioned in an edge region392. Additionally, six guard tones340are included in the edge region391, and the five guard tones340are included in the edge region392. In some embodiments, the guard tones340are included within the 20 MHz channel over which MU-OFDMA frame301is transmitted. In other embodiments, the guard tones340tones that are outside the 20 MHz channel over which the ME-OFDMA frame301is transmitted.

FIG. 3Bis a diagram of an embodiment tone plan for a SU-OFDMA frame302that is communicated over a 20 MHz channel. As shown, the SU-OFDMA frame302includes data and pilot regions315,316and DC tones330. In this example, the data and pilot regions315,316each include one-hundred and twenty-one consecutive data and pilot tones. The DC tones330are positioned in-between the data and pilot regions315,316. The data and pilot region315is positioned in-between six guard tones340and the DC tones330. The data and pilot region316is positioned in-between the DC tones330and five guard tones340. In some embodiments, the guard tones340are included within the 20 MHz channel over which the SU-OFDMA frame302is transmitted. In other embodiments, the guard tones340are positioned outside the 20 MHz channel over which the SU-OFDMA frame302is transmitted.

Embodiments of this disclosure provide tone plans for OFDMA frames communicated over 40 MHz channels.FIG. 4Ais a diagram of an embodiment tone plan for a MU-OFDMA frame401that is communicated over a 40 MHz channel. As shown, the MU-OFDMA frame401includes eighteen 26-tone RUs410, null-data tones420, and DC tones430. Five DC tones430and eight null-data tones420are included in a DC region450. Nine of the 26-tone RUs410are included in a data and pilot region481, and nine of the 26-tone RUs410are included in a data and pilot region482. The DC region450is positioned in-between the data and pilot region481and the data and pilot region482. Four null-data tones420are included in an edge region491, and four null-data tones420are included in an edge region492. Additionally, twelve guard tones440are included in the edge region491, and the eleven guard tones440are included in the edge region492. In some embodiments, the guard tones440are included within the 40 MHz channel over which the MU-OFDMA frame401is transmitted. In other embodiments, the guard tones440tones are outside the 40 MHz channel over which the MU-OFDMA frame401is transmitted.

FIG. 4Bis a diagram of an embodiment tone plan for a SU-OFDMA frame402that is communicated over a 40 MHz channel. As shown, the SU-OFDMA frame402includes data and pilot regions415,416and DC tones430. In this example, the data and pilot regions415,416each include two-hundred and forty-two consecutive data and pilot tones. The DC tones430are positioned in-between the data and pilot regions415,416. The data and pilot region415is positioned in-between twelve guard tones440and the DC tones430. The data and pilot region416is positioned in-between the DC tones430and eleven guard tones440. In some embodiments, the guard tones440are included within the 40 MHz channel over which the SU-OFDMA frame402is transmitted. In other embodiments, the guard tones440tones are outside the 40 MHz channel over which the SU-OFDMA frame402is transmitted.

Embodiments of this disclosure provide tone plans for OFDMA frames communicated over 80 MHz channels.FIG. 5Ais a diagram of an embodiment tone plan for a MU-OFDMA frame501that is communicated over an 80 MHz channel. As shown, the MU-OFDMA frame501includes 26-tone RUs510, portions511,512of a bifurcated 26-tone RU, null-data tones520, and five DC tones530. In this example, the 26-tone RUs510and the portions511,512of the bifurcated RU are distributed over four data and pilot regions581,582,583,584. In particular, the data and pilot region581includes nine 26-tone RUs510and one portion511of the bifurcated RU, and the data and pilot region582includes nine 26-tone RUs510and the remaining portion512of the bifurcated RU. The four data and pilot regions583,584each include nine 26-tone RUs510. The DC region550is positioned in-between the data and pilot region581and the data and pilot region582. The data and pilot region581is positioned in-between the DC region and the data and pilot region584, and the data and pilot region582is positioned in-between the DC region and the data and pilot region583. The data and pilot region584is positioned in-between the data and pilot region581and an edge region591, and the data and pilot region583is positioned in-between the data and pilot region582and an edge region592. Because of their relative positioning with respect to one another, the data and pilot regions581,582may be referred to herein as the inner-most data and pilot regions of the MU-OFDMA frame501, and the data and pilot regions583,584may be referred to herein as the outer-most data and pilot regions of the MU-OFDMA frame501. Eight null-data tones520are included in an edge region591, and eight null-data tones520are included in an edge region592. Additionally, thirteen guard tones540are included in the edge region591, and twelve guard tones540are included in the edge region592. In some embodiments, the guard tones540are included within the 80 MHz channel over which the MU-OFDMA frame501is transmitted. In other embodiments, the guard tones540tones are outside the 80 MHz channel over which the MU-OFDMA frame501is transmitted. Eight null-data tones520are positioned in-between the data and pilot region581,584. Similarly, eight null-data tones520are positioned in-between the data and pilot region582,583.

FIG. 5Bis a diagram of an embodiment tone plan for a SU-OFDMA frame502that is communicated over an 80 MHz channel. As shown, the SU-OFDMA frame502includes data and pilot regions515,516,517,518, portions511,512of a bifurcated 26-tone RU, and five DC tones530. In this example, the data and pilot regions515,516,517,518each include two-hundred and forty-two consecutive data and pilot tones. The five DC tones530are positioned in-between the data and pilot regions515,516. The data and pilot regions515,518are positioned in-between twelve guard tones540and the DC tones530. The data and pilot region516,517are positioned in-between the DC tones530and eleven guard tones540. In some embodiments, the guard tones540are included within the 80 MHz channel over which the SU-OFDMA frame502is transmitted. In other embodiments, the guard tones540tones are outside the 80 MHz channel over which the SU-OFDMA frame502is transmitted.

FIG. 6Ais a diagram of an embodiment tone plan for a MU-OFDMA frame601that is communicated over an 80 MHz channel. The RUs610,611,612, tones620,630,640, and regions650,681,682,683,684,691,692in the MU-OFDMA frame601have similar arrangements and configurations to like components/regions of the MU-OFDMA frame501, except that the DC region650includes seven DC tones630, the edge region691includes twelve guard tones640, and the edge region692includes eleven guard tones640.

FIG. 6Bis a diagram of an embodiment tone plan for a SU-OFDMA frame502that is communicated over an 80 MHz channel. The data and pilot regions in the SU-OFDMA frame602have similar arrangements and configurations to like components/regions of the SU-OFDMA frame502, except that the DC region650includes seven DC tones630, as well as that there are twelve guard tones640positioned outside of the data and pilot region618and eleven guard tones640positioned outside of the data and pilot region617.

Aspects of this disclosure provide embodiment frame formats for use in a wireless environment such as an Institute of Electrical and Electronics Engineers (IEEE) 802.11ax network. Embodiments provide tone plans for the orthogonal frequency division multiple access (OFDMA) resource units (RUs) for 20 MHz, 40 MHz, and 80 MHz OFDMA transmissions. An embodiment at 20 MHz includes 6 null tones on one edge of an orthogonal frequency division multiplexing (OFDM) frame, 5 null tones on the other edge of the OFDM frame, and three null tones in a direct current (DC) region. An embodiment OFDM frame for 40 MHz has 242×2=484 data and pilot tones grouped in RUs, with additional null tones in the DC region and on the edges. Single user (SU) frames are scheduled for a single user. Multi-user OFDMA frames can be scheduled for multiple users. In other embodiments, for 80 MHz OFDM transmission, there are either 5 null tones in the DC region or 7 null tones in the DC region. In another embodiment, 20 MHz, 40 MHz, and 80 MHz OFDMA tone plans use 26-tone RUs, and 20 MHz SU scheduling uses 242-tone RUs. The OFDMA or SU frame may be a downlink frame or an uplink frame.

In an embodiment OFDM frame, there are 8 leftover tones within each 242 tone block. Leftover tones may be used as separators between different RUs, especially smaller size RUs, to reduce leakage from adjacent blocks. Additional null tones near the edge may be used for protection from pulse shaping filters, adjacent blockers, etc. No data is transmitted on the leftover tones, DC tones, or edge tones. That is, leftover tones, DC tones, and edge tones are all null tones. Leftover tones may be adjacent to edge tones, in which case the number of null tones near the edge is equal to the sum of the number of edge tones and the number of leftover tones adjacent to the edge tones. Also, leftover tones may be adjacent to the DC tones, in which case the number of null tones in the DC region is equal to the sum of the number of DC tones and the number of leftover tones adjacent to the DC region. Edge tones may also be known as guard tones.

There are several factors which may be considered in determining tone plans and RU allocation. RUs may be aligned between 20 MHz, 40 MHz, and 80 MHz frame configurations. Null tones in the DC regions and null tones at the edges may be allocated based on spectral mask and carrier frequency offset (CFO) requirements to protect tones in RUs near the edge tones and the DC tones. Other considerations in determining tone plans and RU allocations include the utilization of leftover tones, for example, to align the RUs and protect tones in RUs near DC tones and edge tones. Edge tones, DC tones, and leftover tones are null tones, and are not used for transmitting data or pilots.

Distortion may affect tones in RUs near the edges of OFDMA frames more significantly than tones in RUs near the edges of SU frames. In one example, the tone plans used for both SU frames and OFDMA frames are similar. Alternatively, the tone for for SU frames and OFDMA frames are different. In one example, additional null tones are used in OFDMA frames to provide additional protection for RUs near the edge and in the DC region. Thus, an OFDMA frame may have more null tones near the edge and null tones in the DC region compared to an SU frame. Null tones near the edge are positioned at the edges of the transmission bands as guard tones to mitigate the effect of transmission filtering on the data and pilot tones. Null tones in the DC region are empty subcarriers (i.e. subcarriers that do not carry data/information) that are used by mobile devices to locate the center of the OFDM frequency band.

Embodiments provide tone plans for 40 MHz and 80 MHz OFDM frames. In some embodiments, 5 DC tones are used, for example with 40 ppm CFO. In other embodiments, for example with 80 MHz, 7 DC tones or 5 DC tones may be used. In various embodiments, the null tones are utilized to align the RUs and to protect tones near the DC region and the edge.

In an embodiment 40 MHz tone plan there are 2 242-tone RUs containing data and pilot tones, and 28 tones allocated for null tones in the DC region and null tones near the edge. In one example, there are 5 null tones in the DC region and [12,11] null tones near the edges. The notation [A, B] denotes A edge tones on one edge of an OFDM frame and B edge tones on the other edge of the OFDM frame. In an embodiment 80 MHz tone plan, there are [13,12] null tones near the edges and 5 null tones in the DC region. In another embodiment 80 MHz tone plan, there are [12,11] null tones near the edges and 7 null tones in the DC region. There may be 994 tones for data, pilots, and leftover tones. In one embodiment, the tone plan is the same for SU frames and OFDMA frames. Alternatively, the tone plan for SU frames is different than the tone plan for OFDMA frames.

Before frames are transmitted, transmission filtering may be performed. The transmission filter may be based on the spectral mask. Leftover tones may be used to protect RUs near null tones at the edges and null tones in the DC region.

In OFDMA, different RUs are allocated to different STAs. Any number of RUs may be allocated for a particular STA. Each STA estimates the channel and recovers the entire message. The signaling field is used by each STA to determine which RU(s) are allocated to that particular STA.

FIG. 7illustrates a tone plan740for a 20 MHz OFDMA frame. There are a total of 242 data, pilot, and leftover tones. Leftover tones are used for the protection of RUs near the DC tones and edge tones, to increase the number of null tones in the DC region and the number of null tones near the edges. A leftover tone used to protect the RUs near the DC tones increases the number of null tones in the DC region. Also, a leftover tone used to protect the RUs near the edge tones increases the number of null tones near the edges. DC tones, edge tones, and leftover tones are all null tones. The tones in RUs744include data and pilot tones, and the tones746,747, and742are the leftover tones, which are null tones. Pilot tones may be distributed throughout the RUs in the tones in RUs744. The separate pilot tones carried by an RU may be used to adjust or estimate the phase and/or frequency offsets of data tones carried in the RU. For example, in an uplink OFDMA frame carrying RUs transmitted by different STAs, the pilot tones carried in the respective RUs may be used by a serving AP to perform residual carrier frequency offset estimation on the uplink OFDMA frame. There are 234 data and pilot tones, including the 8 26-tone RUs744and the 26-tone RU745that is split into 13 tones on each side of the null tones in the DC region743. There are 8 leftover tones, which are used to protect RUs near edge tones and DC tones. Two of the leftover tones742are used on each side of the DC tones748. The two leftover tones746are placed adjacent to the 6 edge tones749, for 8 null tones near the edge747. Also, the two leftover tones746are adjacent to the 5 edge tones749for 7 null tones near the edge747.

FIG. 8illustrates tone plans850for a 40 MHz transmission for OFDMA and SU frames. There are 484 tones for data, pilot, and leftover tones, and 28 tones for DC and edge tones. Tone plans850includes the OFDMA tone plan870and the SU tone plan872. The tones in the OFDMA tone plan870are sent to or received from multiple STAs. The tones in the SU tone plan872are sent to or received from a single STA.

The SU tone plan872includes the 5 DC tones852. The 5 DC tones852are included in a DC region. On each side of the DC tones852is a 242-tone RU864. Each 242-tone RU includes 4 pilot tones and 238 data tones. One edge includes 12 edge tones866. The other edge includes 11 edge tones868.

RUs and leftover tones of the OFDMA tone plan870are aligned with RUs of the SU tone plan872. The OFDMA tone plan870includes 5 DC tones852. Four leftover tones854are on each side of the DC tones852for 13 null tones in the DC region853to protect the RUs near the null tones in the DC region853. On one edge there are 12 edge tones860. Four leftover tones856are adjacent to edge tones860for 16 null tones near the edge16. On the other edge are 11 edge tones862and four leftover tones857adjacent to the edge tones862for 15 null tones near the edge863. The 468 data and pilot tones are distributed over 18 26-tone RUs. Nine of the 26-tone RUs are positioned on each side of the DC region853. Each 26-tone RU includes 2 pilot tones and 24 data tones.

FIG. 9illustrates the 80 MHz tone plans950for OFDMA and SU frames. There are 994 data, pilot, and leftover tones, and 30 DC and edge tones. The tone plans950include the OFDMA tone plan979and the SU tone plan978. The tones in the OFDMA tone plan979are sent to or received from multiple STAs. The tones in the SU tone plan978are sent to or received from a single STA. The RUs for the OFDMA tone plan979are aligned with the RUs of the SU tone plan978.

The SU tone plan978contains 5 DC tones966. The RU968is split into two 13-tone portions. The five DC tones966are positioned in-between the respective 13-tone portions of the RU968. The tones in RU970include two sets of 242-tone RUs on each side, for 4 242-tone RUs. 13 edge tones974are at one edge and 12 edge tones975are at the opposite edge.

RUs, DC tones, and edge tones of the OFDMA tone plan979are aligned with RUs, DC tones, and edge tones of the SU tone plan978, respectively. There are 262 pilot and data tones in the OFDMA tone plan979, grouped into 37 26-tone RUs. The OFDMA tone plan979includes 5 DC tones952, which are aligned with DC tones966. There are a total of 5 null tones in the DC region. Also, the OFDMA tone plan979includes 13 edge tones964. 8 leftover tones962are adjacent to the edge tones964, for a total of 21 null tones at the edge963. Also, OFDMA tone plan979contains 12 edge tones965. The leftover tones963are adjacent to the edge tones965, for a total of 20 null tones near the edge967. The 26-tone RU954is split by DC tones952, with 13 tones on each side of DC tones952. There are four sets of 9 26-tone RUs960,956,957, and961. The leftover tones include the tones962,958,959,963. The tones958and959are between sets of 9 26-tone RUs.

FIG. 10illustrates 80 MHz tone plans1080for OFDMA frames and SU frames. There are 294 data, pilot, and leftover tones, and 30 DC and edge tones. The tone plans1080include the OFDMA tone plan1006and the SU tone plan1008. The tones in the OFDMA tone plan1006are sent to or received from multiple STAs. The tones in the SU tone plan1008are sent to or received from a single STA. The RUs, DC tones, and edge tones of the OFDMA tone plan1006are aligned with the RUs, DC tones, and edge tones of the SU tone plan1008, respectively.

The SU tone plan1008contains 7 DC tones1096. There are a total of 7 null tones in the DC region. Also, the RU1098includes two 13-tone portions. The DC tones1096are positioned in-between the respective 13-tone portions of the RU1098. The RUs1000include two sets of 242-tone RUs on each side of the DC tones1096and the RU1098. 12 edge tones1002are at one edge, for a total of 12 null tones at that edge, and 11 edge tones1004are at the opposite edge, for 11 null tones at that edge.

The OFDMA tone plan1006is aligned with the SU tone plan1008. There are a total of 37 26-tone RUs in the OFDMA tone plan1006. The OFDMA tone plan1006includes 7 DC tones1082, for a total of 7 null tones in the DC region. Also, the OFDMA tone plan1006includes 12 edge tones1094and 11 edge tones1095. The leftover tones include four sets of eight tones1092,1088,1089, and1093. The 8 tones1092are adjacent to edge tones1094, for 20 null tones at the edge1093. Also, 8 leftover tones1093are adjacent to edge tones1095, for 21 null tones at the edge1097. The tones1088and the tones1089are between sets of 9 26-tone RUs. The 26 tones1084include 13 tones on each side of the DC tones1082. There are four sets of 9 26-tone RUs1090,1086,1087, and1091

In another embodiment, there are a total of 37 26-tone RUs. One of the 26-tone RUs may be used for scheduling STAs.

Additional examples may include different sized RUs. For example, RUs may contain 26 tones, 52 tones, 106 tones, 242 tones, or another number of tones.

For a downlink frame based on the signaling field of the frame, the receiver determines which RUs are scheduled for that STA. The receiver may perform CFO estimation using the pilots. Residual frequency offset compensation may include estimating a carrier frequency offset based on dedicated pilots carried in OFDMA transmission.

Embodiments include tone plans for 40 MHz and 80 MHz OFDMA transmissions. In one embodiment, the OFDMA tone plan is the same as or similar to the SU tone plan. Alternatively, the OFDMA tone plan is different than the SU tone plan. In an embodiment, there are 5 DC tones for 40 ppm CFO. In an embodiment, 26-tone RUs for OFDMA frames are aligned with 242-tone RUs for SU frames, and one RU does not overlap the position of another RU. In an embodiment, leftover tones are utilized to align RUs and protect tones near DC tones and edge tones. In an embodiment, one 26-tone RU is used for scheduling in 80 MHz.

FIG. 11a block diagram of an embodiment processing system1100for performing methods described herein, which may be installed in a host device. As shown, the processing system1100includes a processor1104, a memory1106, and interfaces1110-1114, which may (or may not) be arranged as shown inFIG. 11. The processor1104may be any component or collection of components adapted to perform computations and/or other processing related tasks, and the memory1106may be any component or collection of components adapted to store programming and/or instructions for execution by the processor1104. In an embodiment, the memory1106includes a non-transitory computer readable medium. The interfaces1110,1112,1114may be any component or collection of components that allow the processing system1100to communicate with other devices/components and/or a user. For example, one or more of the interfaces1110,1112,1114may be adapted to communicate data, control, or management messages from the processor1104to applications installed on the host device and/or a remote device. As another example, one or more of the interfaces1110,1112,1114may be adapted to allow a user or user device (e.g., personal computer (PC), etc.) to interact/communicate with the processing system1100. The processing system1100may include additional components not depicted inFIG. 11, such as long term storage (e.g., non-volatile memory, etc.).

In some embodiments, one or more of the interfaces1110,1112,1114connects the processing system1100to a transceiver adapted to transmit and receive signaling over the telecommunications network.FIG. 12illustrates a block diagram of a transceiver1200adapted to transmit and receive signaling over a telecommunications network. The transceiver1200may be installed in a host device. As shown, the transceiver1200comprises a network-side interface1202, a coupler1204, a transmitter1206, a receiver1208, a signal processor1210, and a device-side interface1212. The network-side interface1202may include any component or collection of components adapted to transmit or receive signaling over a wireless or wireline telecommunications network. The coupler1204may include any component or collection of components adapted to enable bi-directional communication over the network-side interface1202. The transmitter1206may 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 interface1202. The receiver1208may 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 interface1202into a baseband signal. The signal processor1210may 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)1212, or vice-versa. The device-side interface(s)1212may include any component or collection of components adapted to communicate data-signals between the signal processor1210and components within the host device (e.g., the processing system1100, local area network (LAN) ports, etc.).