Patent Description:
Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to legacy compatible signaling for channel bonding.

In order to address the issue of increasing bandwidth requirements demanded for wireless communications systems, different schemes are being developed to allow multiple user terminals to communicate with a single access point by sharing the channel resources while achieving high data throughputs. Multiple-input multiple-output (MIMO) technology represents one such approach that has recently emerged as a popular technique for next generation communication systems. MIMO technology has been adopted in several emerging wireless communications standards, such as the Institute of Electrical and Electronics Engineers (IEEE) <NUM> standard. The IEEE <NUM> standard denotes a set of Wireless Local Area Network (WLAN) air interface standards developed by the IEEE <NUM> committee for short-range communications (e.g., tens of meters to a few hundred meters).

A MIMO system employs multiple (NT) transmit antennas and multiple (NR) receive antennas for data transmission. A MIMO channel formed by the Nr transmit and NR receive antennas may be decomposed into NS independent channels, which are also referred to as spatial channels, where Ns ≤ min{NT , NR}. Each of the NS independent channels corresponds to a dimension. The MIMO system can provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.

In wireless networks with a single Access Point (AP) and multiple user stations (STAs), concurrent transmissions may occur on multiple channels toward different stations, both in the uplink and downlink direction. Many challenges are present in such systems. One solution is provided in <NPL>, disclosing a method in which an RTS is sent including a Service field to both legacy and VHT stations. Although both type of stations can receive the RTS their behaviour to reply is different. While legacy stations proceed to send a CTS if they are addressed by the RTS, VHT stations check the Individual/Group bit in the TA field , whether it is set to <NUM>, and then process the TBD parameter in RXVECTOR to obtain the dynamic bandwidth operation field and the channel bandwidth indication field.

Aspects of the present disclosure provide techniques for providing legacy compatible signaling for MU communication channel bonding by hiding information (e.g., channel bonding information) in a legacy frame that may be decodable by stations (STAs) supporting channel bonding (e.g., non-legacy STAs).

The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims.

The techniques described herein may be used for various broadband wireless communication systems, including communication systems that are based on an orthogonal multiplexing scheme. Examples of such communication systems include Spatial Division Multiple Access (SDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems, and so forth. An SDMA system may utilize sufficiently different directions to simultaneously transmit data belonging to multiple user terminals. A TDMA system may allow multiple user terminals to share the same frequency channel by dividing the transmission signal into different time slots, each time slot being assigned to different user terminal. An OFDMA system utilizes orthogonal frequency division multiplexing (OFDM), which is a modulation technique that partitions the overall system bandwidth into multiple orthogonal sub-carriers. These sub-carriers may also be called tones, bins, etc. With OFDM, each sub-carrier may be independently modulated with data. An SC-FDMA system may utilize interleaved FDMA (IFDMA) to transmit on sub-carriers that are distributed across the system bandwidth, localized FDMA (LFDMA) to transmit on a block of adjacent sub-carriers, or enhanced FDMA (EFDMA) to transmit on multiple blocks of adjacent sub-carriers. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDMA.

The teachings herein may be incorporated into (e.g., implemented within or performed by) a variety of wired or wireless apparatuses (e.g., nodes). In some aspects, a wireless node implemented in accordance with the teachings herein may comprise an access point or an access terminal.

An access point ("AP") may comprise, be implemented as, or known as a Node B, a Radio Network Controller ("RNC"), an evolved Node B (eNB), a Base Station Controller ("BSC"), a Base Transceiver Station ("BTS"), a Base Station ("BS"), a Transceiver Function ("TF"), a Radio Router, a Radio Transceiver, a Basic Service Set ("BSS"), an Extended Service Set ("ESS"), a Radio Base Station ("RBS"), or some other terminology.

An access terminal ("AT") may comprise, be implemented as, or known as a subscriber station, a subscriber unit, a mobile station, a remote station, a remote terminal, a user terminal, a user agent, a user device, user equipment, a user station, or some other terminology. In some implementations, an access terminal may comprise a cellular telephone, a cordless telephone, a Session Initiation Protocol ("SIP") phone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device having wireless connection capability, a Station ("STA"), or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or smart phone), a computer (e.g., a laptop), a portable communication device, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device, or a satellite radio), a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. In some aspects, the node is a wireless node. Such wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link.

<FIG> illustrates a multiple-access multiple-input multiple-output (MIMO) system <NUM> with access points and user terminals. For simplicity, only one access point <NUM> is shown in <FIG>. An access point is generally a fixed station that communicates with the user terminals and may also be referred to as a base station or some other terminology. A user terminal may be fixed or mobile and may also be referred to as a mobile station, a wireless device or some other terminology. Access point <NUM> may communicate with one or more user terminals <NUM> at any given moment on the downlink and uplink. The downlink (i.e., forward link) is the communication link from the access point to the user terminals, and the uplink (i.e., reverse link) is the communication link from the user terminals to the access point. A user terminal may also communicate peer-to-peer with another user terminal. A system controller <NUM> couples to and provides coordination and control for the access points.

While portions of the following disclosure will describe user terminals <NUM> capable of communicating via Spatial Division Multiple Access (SDMA), for certain aspects, the user terminals <NUM> may also include some user terminals that do not support SDMA. Thus, for such aspects, an access point (AP) <NUM> may be configured to communicate with both SDMA and non-SDMA user terminals. This approach may conveniently allow older versions of user terminals ("legacy" stations) to remain deployed in an enterprise, extending their useful lifetime, while allowing newer SDMA user terminals to be introduced as deemed appropriate.

The system <NUM> employs multiple transmit and multiple receive antennas for data transmission on the downlink and uplink. The access point <NUM> is equipped with Nap antennas and represents the multiple-input (MI) for downlink transmissions and the multiple-output (MO) for uplink transmissions. A set of K selected user terminals <NUM> collectively represents the multiple-output for downlink transmissions and the multiple-input for uplink transmissions. For pure SDMA, it is desired to have Nap ≥ K ≥ <NUM> if the data symbol streams for the K user terminals are not multiplexed in code, frequency or time by some means. K may be greater than Nap if the data symbol streams can be multiplexed using TDMA technique, different code channels with CDMA, disjoint sets of subbands with OFDM, and so on. Each selected user terminal transmits user-specific data to and/or receives user-specific data from the access point. In general, each selected user terminal may be equipped with one or multiple antennas (i.e., Nut ≥ <NUM>). The K selected user terminals can have the same or different number of antennas.

The system <NUM> may be a time division duplex (TDD) system or a frequency division duplex (FDD) system. For a TDD system, the downlink and uplink share the same frequency band. For an FDD system, the downlink and uplink use different frequency bands. MIMO system <NUM> may also utilize a single carrier or multiple carriers for transmission. Each user terminal may be equipped with a single antenna (e.g., in order to keep costs down) or multiple antennas (e.g., where the additional cost can be supported). The system <NUM> may also be a TDMA system if the user terminals <NUM> share the same frequency channel by dividing transmission/reception into different time slots, each time slot being assigned to different user terminal <NUM>.

<FIG> illustrates a block diagram of access point <NUM> and two user terminals <NUM> and 120x in MIMO system <NUM>. The access point <NUM> is equipped with Nt antennas 224a through 224t. User terminal <NUM> is equipped with Nut,m antennas 252ma through 252mu, and user terminal 120x is equipped with Nut,x antennas 252xa through 252xu. The access point <NUM> is a transmitting entity for the downlink and a receiving entity for the uplink. Each user terminal <NUM> is a transmitting entity for the uplink and a receiving entity for the downlink. As used herein, a "transmitting entity" is an independently operated apparatus or device capable of transmitting data via a wireless channel, and a "receiving entity" is an independently operated apparatus or device capable of receiving data via a wireless channel. In the following description, the subscript "dn" denotes the downlink, the subscript "up" denotes the uplink, Nup user terminals are selected for simultaneous transmission on the uplink, Ndn user terminals are selected for simultaneous transmission on the downlink, Nup may or may not be equal to Ndn, and Nup and Ndn may be static values or can change for each scheduling interval. The beam-steering or some other spatial processing technique may be used at the access point and user terminal.

On the uplink, at each user terminal <NUM> selected for uplink transmission, a TX data processor <NUM> receives traffic data from a data source <NUM> and control data from a controller <NUM>. TX data processor <NUM> processes (e.g., encodes, interleaves, and modulates) the traffic data for the user terminal based on the coding and modulation schemes associated with the rate selected for the user terminal and provides a data symbol stream. A TX spatial processor <NUM> performs spatial processing on the data symbol stream and provides Nut,m transmit symbol streams for the Nut,m antennas. Each transmitter unit (TMTR) <NUM> receives and processes (e.g., converts to analog, amplifies, filters, and frequency upconverts) a respective transmit symbol stream to generate an uplink signal. Nut,m transmitter units <NUM> provide Nut,m uplink signals for transmission from Nut,m antennas <NUM> to the access point.

Nup user terminals may be scheduled for simultaneous transmission on the uplink. Each of these user terminals performs spatial processing on its data symbol stream and transmits its set of transmit symbol streams on the uplink to the access point.

At access point <NUM>, Nap antennas 224a through 224ap receive the uplink signals from all Nup user terminals transmitting on the uplink. Each antenna <NUM> provides a received signal to a respective receiver unit (RCVR) <NUM>. Each receiver unit <NUM> performs processing complementary to that performed by transmitter unit <NUM> and provides a received symbol stream. An RX spatial processor <NUM> performs receiver spatial processing on the Nap received symbol streams from Nap receiver units <NUM> and provides Nap recovered uplink data symbol streams. The receiver spatial processing is performed in accordance with the channel correlation matrix inversion (CCMI), minimum mean square error (MMSE), soft interference cancellation (SIC), or some other technique. Each recovered uplink data symbol stream is an estimate of a data symbol stream transmitted by a respective user terminal. An RX data processor <NUM> processes (e.g., demodulates, deinterleaves, and decodes) each recovered uplink data symbol stream in accordance with the rate used for that stream to obtain decoded data. The decoded data for each user terminal may be provided to a data sink <NUM> for storage and/or a controller <NUM> for further processing.

On the downlink, at access point <NUM>, a TX data processor <NUM> receives traffic data from a data source <NUM> for Ndn user terminals scheduled for downlink transmission, control data from a controller <NUM>, and possibly other data from a scheduler <NUM>. The various types of data may be sent on different transport channels. TX data processor <NUM> processes (e.g., encodes, interleaves, and modulates) the traffic data for each user terminal based on the rate selected for that user terminal. TX data processor <NUM> provides Ndn downlink data symbol streams for the Ndn user terminals. A TX spatial processor <NUM> performs spatial processing (such as a precoding or beamforming, as described in the present disclosure) on the Ndn downlink data symbol streams, and provides Nap transmit symbol streams for the Nap antennas. Each transmitter unit <NUM> receives and processes a respective transmit symbol stream to generate a downlink signal. Nap transmitter units <NUM> providing Nap downlink signals for transmission from Nap antennas <NUM> to the user terminals.

At each user terminal <NUM>, Nut,m antennas <NUM> receive the Nap downlink signals from access point <NUM>. Each receiver unit <NUM> processes a received signal from an associated antenna <NUM> and provides a received symbol stream. An RX spatial processor <NUM> performs receiver spatial processing on Nut,m received symbol streams from Nut,m receiver units <NUM> and provides a recovered downlink data symbol stream for the user terminal. The receiver spatial processing is performed in accordance with the CCMI, MMSE or some other technique. An RX data processor <NUM> processes (e.g., demodulates, deinterleaves and decodes) the recovered downlink data symbol stream to obtain decoded data for the user terminal.

At each user terminal <NUM>, a channel estimator <NUM><NUM> estimates the downlink channel response and provides downlink channel estimates, which may include channel gain estimates, SNR estimates, noise variance and so on. Similarly, a channel estimator <NUM> estimates the uplink channel response and provides uplink channel estimates. Controller <NUM> for each user terminal typically derives the spatial filter matrix for the user terminal based on the downlink channel response matrix Hdn,m for that user terminal. Controller <NUM> derives the spatial filter matrix for the access point based on the effective uplink channel response matrix Hup,eff. Controller <NUM> for each user terminal may send feedback information (e.g., the downlink and/or uplink eigenvectors, eigenvalues, SNR estimates, and so on) to the access point. Controllers <NUM> and <NUM> also control the operation of various processing units at access point <NUM> and user terminal <NUM>, respectively.

As illustrated, in <FIG> and <FIG>, one or more user terminals <NUM> may send one or more High Efficiency WLAN (HEW) packets <NUM>, with a preamble format as described herein (e.g., in accordance with one of the example formats shown in FIGs. 3A-<NUM>), to the access point <NUM> as part of a UL MU-MIMO transmission, for example. Each HEW packet <NUM> may be transmitted on a set of one or more spatial streams (e.g., up to <NUM>). For certain aspects, the preamble portion of the HEW packet <NUM> may include tone-interleaved LTFs, subband-based LTFs, or hybrid LTFs (e.g., in accordance with one of the example implementations illustrated in <FIG> and <FIG>).

The HEW packet <NUM> may be generated by a packet generating unit <NUM> at the user terminal <NUM>. The packet generating unit <NUM> may be implemented in the processing system of the user terminal <NUM>, such as in the TX data processor <NUM>, the controller <NUM>, and/or the data source <NUM>.

After UL transmission, the HEW packet <NUM> may be processed (e.g., decoded and interpreted) by a packet processing unit <NUM> at the access point <NUM>. The packet processing unit <NUM> may be implemented in the process system of the access point <NUM>, such as in the RX spatial processor <NUM>, the RX data processor <NUM>, or the controller <NUM>. The packet processing unit <NUM> may process received packets differently, based on the packet type (e.g., with which amendment to the IEEE <NUM> standard the received packet complies). For example, the packet processing unit <NUM> may process a HEW packet <NUM> based on the IEEE <NUM> HEW standard, but may interpret a legacy packet (e.g., a packet complying with IEEE <NUM>. 11a/b/g) in a different manner, according to the standards amendment associated therewith.

In certain networks (e.g., <NUM>. 11ax networks), the bandwidth of a basic service set (BSS) may be up to <NUM> and may support multi-user transmissions aimed at increasing efficiency. In certain other networks, the bandwidth of the BSS may be any multiple of <NUM> (e.g., <NUM>, and so on). For example, a trigger frame may be used to solicit data from multiple stations in different sub channels in parallel, wherein a sub channel may be <NUM> in width or consist of one or more portions (e.g., Resource Units) of the subchannel.

However, one problem that exists is that such networks often also support legacy stations (STAs) (e.g., 11a, 11n, 11ac, etc.), which always transmit in Single User (SU) mode and are not capable of supporting multi-user transmissions. In general, a legacy station is not capable of interpreting a new functionality, that other STAs in the network are capable of interpreting. For example, as illustrated in <FIG>, when legacy packets are sent, multi-user transmissions may not be performed since there is no signaling for legacy STAs to support the multi-user transmissions. This may result in a loss of efficiency since when legacy STAs are transmitting, only the primary <NUM> channel bandwidth can be used even though the secondary channels (e.g., <NUM>, <NUM>, and/or <NUM>) are idle and could be used for transmitting to other STAs.

Thus, aspects of the present invention present techniques for legacy compatible signaling for channel bonding, which may enable a more efficient use of bandwidth (e.g., by enabling secondary channels to be used for delivering and receiving PPDUs to multiple STAs, while the primary channel is used by legacy STAs). More specifically, aspects of the present disclosure techniques for enabling downlink (DL) and uplink (UL) multi-user channel allocation in a system supporting legacy and non-legacy (e.g., high efficiency (HE)) STAs. In some cases, this may involve "hiding" information (e.g., channel bonding information) in a legacy frame that may enable HE STAs to transmit or receive on secondary channels in parallel with legacy STAs transmitting or receiving on the primary channel. According to certain aspects, the channel bonding information may be decodable by HE stations but may not be decodable by legacy stations.

<FIG> illustrates example operations <NUM> that are performed by a device for providing legacy compatible signaling for channel bonding, in accordance with certain aspects of the present disclosure. Operations <NUM> may be performed by an apparatus, such as an access point (e.g., AP <NUM>). Operations <NUM> begin at <NUM>, by generating a frame having channel bonding information indicating one or more channels available for multi-user (MU) communication by one or more wireless nodes. At <NUM>, the apparatus outputs the frame for transmission.

<FIG> illustrates example operations <NUM> that may be performed by a device for receiving legacy compatible signaling for channel bonding, in accordance with certain aspects of the present disclosure. Operations <NUM> may be performed by an apparatus, such as a wireless node/station (e.g., STA <NUM>). Operations <NUM> may begin at <NUM>, by obtaining a frame comprising channel bonding information. At <NUM>, the wireless node determines, based on the channel bonding information contained in the frame, one or more channels available for multi-user (MU) transmissions. At <NUM>, the wireless node outputs data for transmission on the one or more of the channels determined to be available for MU communication.

As noted above, signaling may be provided, by an access point, in a legacy frame that may enable HE STAs to transmit or receive on secondary channels in parallel with legacy STAs (i.e., STAs that do not support channel bonding) transmitting or receiving on the primary channel. The legacy compatible signaling may be provided in various ways. For example, one way to provide the legacy compatible signaling for channel bonding may be to provide the signaling in a Service field of a PHY Protocol Data Unit (PPDU).

<FIG> illustrates a frame format for a PPDU 600A, in accordance with certain aspects of the present disclosure. As illustrated, the PPDU may comprise an L-STF/L-LTF/LSIG field 602A, a Service field 604A, and a PHY Service Data Unit 606A. Additionally, as illustrated in <FIG>, the Service field 604A may comprise <NUM> bits (e.g., bits <NUM>-<NUM>), which may be split up into a Scrambler Initialization portion 608B (e.g., spanning bits <NUM>-<NUM>) and a Reserved portion 610B (e.g., spanning bits <NUM>-<NUM><NUM>).

According to invention, , the legacy compatible signaling for channel bonding is peprovided in the Service field 604A. Additionally, in some cases, one or more of the bits in the Reserved portion 610B of the Service field 604A may be used to protect the information carried in the Service field 604A. Further, bits B8-B15 may be set differently depending on a type of the PPDU 600A. For example, if the PPDU 600A comprises a high throughput (HT) PPDU, bits B8-B15 may be set to all os. Additionally, if the PPDU 600A comprises a very high throughput (VHT) PPDU, bits B8-B15 may comprise a SIG-B cyclic redundancy check (CRC).

According to certain aspects, the legacy compatible signaling for channel bonding may comprise a list of idle channels (e.g., a channel index, CH_IDX) that may be used for multi-user UL/DL transmissions in parallel with legacy transmissions (e.g., 11a, 11n, 11ac, and/or HE single user transmissions). In some cases, a list of multi-user STAs that are allowed to access the idle channels may be provided by the AP in advance to the list of idle channels.

<FIG> illustrate an example mapping of the secondary idle channel bandwidths to bits in the scrambler initialization portion 608B of the Service field. For example, <FIG> illustrates a secondary <NUM> channel bandwidth that may comprise a primary channel bandwidth, CB_P2, and a corresponding secondary channel bandwidth, CB_S2. Additionally, as illustrated, a secondary <NUM> channel bandwidth may comprise primary channel bandwidths, CB_P3 and CB_P4, and corresponding secondary channel bandwidths, CB_S3 and CB_S4.

As illustrated in <FIG>, the idle channel bandwidths listed in the channel index, CHB IDX, may be indicated using a combination of three or more bits of the scrambler initialization portion 608B of the Service field 604A. For example, a value of <NUM> (i.e., <NUM>) may indicate that no secondary channels are idle while a value of <NUM> (i.e., <NUM>) may indicate that primary channels CB_P3 and CB_P4 of the secondary <NUM> channel bandwidth are idle. While <FIG> illustrates one mapping of bit values to idle channels, it should be understood that other mappings may exist.

According to certain aspects, contiguous channel bonding may be supported using the secondary idle channels illustrated in <FIG>. For example, as illustrated, there may be three channels which are eligible for channel bonding (e.g., CB_P2, CB_P3, and CB_P4) and once a primary channel is selected (e.g., CB_P2) by a STA for transmission, the AP may also inform the STA that the STA may expand its transmission over the corresponding secondary channel (e.g., CB_S2). According to certain aspects, if contiguous channel bonding is supported the bandwidth of transmissions may be up to <NUM>, while if contiguous channel bonding is not supported, the bandwidth of the transmissions may only be <NUM> on the idle secondary channels.

According to certain aspects, the mapping illustrated in <FIG> assumes a basic service set (BSS) bandwidth of <NUM>. However, when the BSS bandwidth is lower, the number of bits needed to indicate the idle channels may be less (e.g., <NUM> bits instead of <NUM>). Thus, the left over bit may be used for scrambling. For example, when the BSS bandwidth is <NUM>, the most significant bit may be assigned to the scrambler. Additionally, the left over bit may be used for providing better resolution. For example, when the BSS bandwidth is <NUM>, each bit can indicate a status of each <NUM> channel.

As noted above, another way to provide legacy compatible signaling for channel boding, may be to indicate a list of idle channels in the reserved portion of the Service field.

For example, as illustrated in <FIG>, a bitmap of <NUM> bits may be provided in which each bit of the bitmap may indicate a different idle channel (e.g., CB_P2, CB_S2, CB_P3, CB_S3, etc., as illustrated in <FIG>) that may be available for channel bonding. Additionally, one bit in the reserved portion of the service field may be used as a parity bit to protect (e.g., used for checking for errors) the <NUM>-bit bitmap sequence. According to certain aspects, the bandwidth of transmissions may be <NUM> for this option. Additionally, according to certain aspects, this option may inherit request to send (RTS)/clear to send (CTS) bandwidth signaling from <NUM>. 11ac and may maintain <NUM> bit (in an RTS) and <NUM> bits (in a CTS) for scrambling.

According to certain aspects, an HE AP may define one or more "alternate temporary primary channels" (e.g., the secondary idle channel bandwidths illustrated in <FIG>). In some cases, the AP may allocate (or pre-allocate meaning allocated before the actual availability of the channels is signaled) each of its HE STA a different alternate temporary primary channel.

<FIG> illustrates that, according to certain aspects, at some point before a (legacy data) transmission with limited bandwidth, the AP may send a channel allocation (CHA) frame (e.g., a data frame, RTS frame, CTS frame, etc.), comprising legacy compatible signaling (e.g., channel bonding information) for channel bonding, notifying HE STAs of a possible simultaneous HE transmission (i.e., MU transmissions) on the alternate temporary primary channels. In some cases, the channel bonding information in the CHA frame may comprise at least one bit indicating whether or not one or more of the allocated channels are available for MU communication. In some cases, the at least one bit may comprise a plurality of bits corresponding to the one or more channels, each bit indicating whether or not the corresponding one or more channels are available for MU communication.

According to certain aspects, and which will be described in greater detail below, the HE AP may transmit the channel allocation frame to a legacy STA which may receive the channel allocation in a primary channel (e.g., the <NUM> primary channel), as illustrated in <FIG>. The channel allocation frame may also be received by other HE STAs which, upon receiving the channel allocation frame, may switch and wait for (HE) PPDUs in the alternate temporary primary channels indicated in the channel allocation frame. According to certain aspects, the HE STAs may stay on the alternate temporary primary channel for a time indicated in the channel allocation frame or for a predefined time negotiated outside of the channel allocation frame.

<FIG> illustrates that the time after which PPDU transmissions on the alternate temporary primary channels is initiated may be longer than the time at which the transmission on the primary channel is initiated. For example, <FIG> illustrates that the time at which PPDUs are transmitted on the primary (e.g., <NUM>) channel, T1, may be SIFS time after transmission of the channel allocation frame, whereas the time at which PPDUs are transmitted on the alternate temporary primary channels, T2, may be PIFS time after transmission of the channel allocation frame. According to certain aspects, transmitting on the alternate temporary primary channels at a later time than on the primary channel may avoid ambiguities during the detection of the bandwidth of the PPDU transmission sent on the primary channel.

<FIG> illustrates a timeline of providing legacy compatible signaling for channel boding for DL PPDUs, in which the channel allocation frame, as described above, comprises an RTS frame. For example, as illustrated, an HE AP may transmit an RTS frame <NUM> to legacy STA1 on the primary <NUM> channel, initiating (or during) a legacy transmission opportunity (TXOP). According to certain aspects, the Service field of the RTS frame <NUM> may comprise a list of channels (e.g., the CHB_IDX, as described above) that are idle and available for channel bonding. As noted above, the bandwidth/channel bonding signaling may be provided in a scrambler initialization portion or a reserved portion of the service field. Additionally, in some cases, the RTS frame may be duplicated (e.g., if the AP is capable, it may transmit "enhanced" RTS frames <NUM> to non-legacy STAs <NUM> and <NUM>).

As illustrated in <FIG>, upon reception of the RTS frame <NUM> from the AP, STA1 may respond with a CTS frame <NUM>, indicating that the primary channel is idle. Additionally, non-intended receivers that are capable of channel bonding (e.g., channel bonding (CB) STAs <NUM> and <NUM>) may receive the RTS frame <NUM> and determine the list of idle channels (i.e., CHB_IDX). For example, the CB STAs may check if their pre-allocated channel bonding channel is included in the list of idle channels. If the CB STA determines that one of its pre-allocated channel bonding channels is in the idle channel list, the CB STA may synchronize to one or more of the pre-allocated channel bonding channels to receive DL buffer units (BUs) (i.e., downlink data). According to certain aspects, the CB STA may have <NUM>*Short Interface Space (SIFS) + CTSTxTime to synchronize. In some cases, a full duplex mode may be supported in which the CB STAs may be able to transmit UL BUs while the AP is transmitting DL BUs to the STAs not supporting channel bonding.

As illustrated in <FIG>, the channel bonding STA may then receive DL BUs <NUM> from the AP in the allocated channel bonding channels in parallel with data delivery to legacy STA1. The STAs may then transmit acknowledgements (ACKs) in their allocated channel bandwidths.

As noted above, channel bonding STAs may receive an RTS frame <NUM> intended for a legacy station and may determine if a pre-allocated channel bonding channel is included within a list of idle channels in the RTS frame. However, the CB STAs scheduled to receive DL BUs during a legacy TXOP need to know which of the channels in CB_IDX list (i.e., the list of idle channels) are pre-allocated for their DL BUs.

According to certain aspects, an AP may provide STAs with an indication of an assignment of pre-allocated channels in various ways. For example, an AP may deliver the pre-allocated channels assignment information in a beacon that precedes the beacon interval (BI) during which the RTS with CB signaling (i.e., the list of idle channels) is sent. According to certain aspects, more than one CB STA may be specified for a given CB channel and the indication may be valid for one BI.

According to certain aspects, the AP may deliver the pre-allocated channels assignment information in a target wake time (TWT) element that precedes a TWT service period (SP) during which the RTS with CB signaling is sent. Similarly, more than one CB TWT STA may be specified for a given CB channel and the indication may be valid for one or more TWT SPs.

According to certain aspects, the AP may deliver the pre-allocated channels assignment information in a frame that is sent to the CB STA(s) prior to the RTS frame with CB signaling. For example, the AP may send a Trigger to the CB STA(s) at a time of SIFS or more prior to transmitting the RTS frame. The indication may be valid for a pre-defined amount of time, which may be negotiated or specified in the frame itself.

Additionally, in some cases, the AP may deliver the allocated channels assignment information in the channel allocation frame (e.g., an RTS and/or CTS frame) itself, which may be valid for a pre-defined amount of time.

<FIG> illustrates a timeline of providing legacy compatible signaling for channel boding for UL PPDUs, in which the channel allocation frame, as described above, comprises an CTS frame. For example, a legacy STA (e.g., STA1) may transmit an RTS <NUM> to an HE AP. Upon reception of the RTS frame <NUM>, the HE AP may transmit a CTS frame <NUM> to STA1 during a legacy TXOP. According to certain aspects, the Service field of the CTS frame <NUM> may comprise a list of channels (e.g., CHB_IDX) that are idle and available for channel bonding. As noted above, the bandwidth/channel bonding signaling may be provided in a scrambler initialization portion or a reserved portion of the service field. Additionally, in some cases, the CTS frame <NUM> may be duplicated (e.g., if the AP is capable, it may transmit "enhanced" CTS frames <NUM> to CB STAs <NUM> and <NUM>). In some cases, the AP may also transmit a CTS frame as a CTS-to-self for STA1.

According to certain aspects, upon reception of the CTS frame, STA1 may respond with data (i.e., UL BUs) <NUM>. Additionally, non-intended receivers that are capable of channel bonding (e.g., channel bonding (CB) STAs <NUM> and <NUM>) may receive the CTS frame <NUM> and determine the list of idle channels (i.e., CHB_IDX). For example, the CB STAs may check if their pre-allocated channel bonding channel is included in the list of idle channels. If the CB STA determines that one of its pre-allocated channel bonding channels is in the idle channel list, the CB STA may synchronize to one or more of the pre-allocated channel bonding channels to transmit UL buffer units (BUs). In some cases, the CBs may be able to randomly select one of the idle channels to transmit on. The CB STAs may then transmit data (i.e., UL BUs) on their indicated CB channels either after SIFS, staggered in time, or, if the medium was idle PIFS, before the CTS, as illustrated in <FIG>.

According to certain aspects, in some cases, a full duplex mode may be supported in which the CB STAs may be able to receive DL BUs from the AP while the AP is receiving UL BUs from the STAs not supporting channel bonding.

As noted above, CB STAs may receive an CTS frame intended for a legacy station and may determine if a pre-allocated channel bonding channel is included within a list of idle channels in the CTS frame. However, the CB STAs scheduled to transmit UL BUs during a legacy TXOP need to know which of the channels in CB_IDX list (i.e., the list of idle channels) are pre-allocated for their UL BUs. Knowing the allocated channels may be particularly important if the access in the CB channels is done SIFS time any only be one CB STA (i.e., without contention).

According to certain aspects, the AP may deliver the information about the allocation of CB channels in a Beacon preceding the beacon interval (BI) during which CTS with CB signaling is sent. According to certain aspects, more than one CB STA can be specified for a given CB channel and the indication may be valid for one BI. Additionally, this option may be available when CB STAs are allowed to contend for the CB channel.

According to certain aspects, the AP may deliver the information about the allocation of CB channels in a TWT element that precedes a TWT SP during which the CTS with CB signaling is sent. Similarly, more than one CB TWT STA may be specified for a given CB channel and the indication may be valid for one or more TWT SPs.

According to certain aspects, the AP may deliver the information about the allocation of CB channels in a frame that is sent to the CB STA(s) prior to the CTS frame with CB signaling. For example, the AP may send a Trigger to the CB STA(s) at a time of SIFS or more prior to transmitting the CTS frame. The indication may be valid for a pre-defined amount of time, which may be negotiated or specified in the frame itself.

According to certain aspects, the information about the allocation of CB channels may also include an indication of whether the allocated CB channel assigned for DL or UL. In some cases, the information about whether the CB channel is assigned for DL or UL may be indicated in the Service field of the RTS frame and/or the CTS frame which includes the indication about which secondary channels are idle.

For example, operations <NUM> illustrated in <FIG> correspond to means 400A illustrated in <FIG>. Additionally, operations <NUM> illustrated in <FIG> correspond to means 500A illustrated in <FIG>.

For example, means for transmitting (or means for outputting for transmission) may comprise a transmitter (e.g., the transmitter unit <NUM>) and/or an antenna(s) <NUM> of the access point <NUM> or the transmitter unit <NUM> and/or antenna(s) <NUM> of the user terminal <NUM> illustrated in <FIG>. Means for receiving (or means for obtaining) may comprise a receiver (e.g., the receiver unit <NUM>) and/or an antenna(s) <NUM> of the access point <NUM> or the receiver unit <NUM> and/or antenna(s) <NUM> of the user terminal <NUM> illustrated in <FIG>. Means for processing, means for generating, means for performing frequency offset adjustment, means for determining, means for using (e.g., means for using one or more bits of a service field), and/or means for providing may comprise a processing system, which may include one or more processors, such as the RX data processor <NUM>, the TX data processor <NUM>, the TX spatial processor <NUM>, and/or the controller <NUM> of the access point <NUM> or the RX data processor <NUM>, the TX data processor <NUM>, the TX spatial processor <NUM>, and/or the controller <NUM> of the user terminal <NUM> illustrated in <FIG>.

In some cases, rather than actually transmitting a frame a device may have an interface to output a frame for transmission (a means for outputting). For example, a processor may output a frame, via a bus interface, to a radio frequency (RF) front end for transmission. Similarly, rather than actually receiving a frame, a device may have an interface to obtain a frame received from another device (a means for obtaining). For example, a processor may obtain (or receive) a frame, via a bus interface, from an RF front end for reception.

The steps of a method or algorithm described in connection with the present disclosure may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in any form of storage medium that is known in the art. Some examples of storage media that may be used include random access memory (RAM), read only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM and so forth. A storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium.

The functions described may be implemented in hardware, software, firmware, or any combination thereof.

The processor may be responsible for managing the bus and general processing, including the execution of software stored on the machine-readable media. Machine-readable media may include, by way of example, RAM (Random Access Memory), flash memory, ROM (Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The computer-program product may comprise packaging materials.

In a hardware implementation, the machine-readable media may be part of the processing system separate from the processor. However, as those skilled in the art will readily appreciate, the machine-readable media, or any portion thereof, may be external to the processing system. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer product separate from the wireless node, all which may be accessed by the processor through the bus interface.

The processing system may be configured as a general-purpose processing system with one or more microprocessors providing the processor functionality and external memory providing at least a portion of the machine-readable media, all linked together with other supporting circuitry through an external bus architecture. Alternatively, the processing system may be implemented with an ASIC (Application Specific Integrated Circuit) with the processor, the bus interface, the user interface in the case of an access terminal), supporting circuitry, and at least a portion of the machine-readable media integrated into a single chip, or with one or more FPGAs (Field Programmable Gate Arrays), PLDs (Programmable Logic Devices), controllers, state machines, gated logic, discrete hardware components, or any other suitable circuitry, or any combination of circuits that can perform the various functionality described throughout this disclosure.

The machine-readable media may comprise a number of software modules. The software modules include instructions that, when executed by the processor, cause the processing system to perform various functions.

A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.

Claim 1:
An apparatus (<NUM>) for wireless communications, comprising:
a processing system configured to generate a frame including a service field, the service field including a plurality of bits indicating channel bonding information indicating whether each of a plurality of channels are available for multi-user, MU, communication by one or more wireless nodes of a first type, the one or more wireless nodes of the first type having a first MU communication capability, wherein
the frame is decodable by the one or more wireless nodes of the first type and one or more wireless nodes of a second type, the one or more wireless nodes of the second type not having the first MU communication capability; and
the channel bonding information is interpretable by the one or more wireless nodes of the first type but not interpretable by the one or more wireless nodes of the second type; and
a first interface configured to output the frame for transmission.