Patent Description:
Relevant background art may be found in documents <CIT> and <CIT>.

In accordance with the present invention, an access point and a method, as set forth in the independent claims are provided. Additional embodiments of the invention are described in the dependent claims.

Mechanisms may be used for multi-channel (MC) setup and access and waveform designs for millimeter wave (mmW) systems. An access point (AP) that is part of a basic service set (BSS) may provide multi-channel (MC) access to one or more stations (STAs) in the BSS. The AP may monitor for beacon frames transmitted by other access point/personal basic service set (PBSS) control point (AP/PCP) associated with overlapping basic service sets (OBSSs). The monitored beacon frames may include service period (SP) scheduling information for the OBSS. The AP may generate an allocations at least one SPs and/or contention based access periods (CBAPs) channels to be used in a beacon interval in consideration of the SP scheduling information for the OBSS. The AP may transmit a beacon frame STA(s) indicating the SP/CBAP allocations. Other mechanisms may include simultaneous transmission of multiple single carrier (SC) waveforms with non-overlapping waveforms to multiple STAs.

<FIG> is a diagram illustrating an example communications system <NUM>. For example, the communications systems <NUM> may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word discrete Fourier transform Spread orthogonal frequency division multiplexing (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

As shown in <FIG>, the communications system <NUM> may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) <NUM>, a core network (CN) <NUM>, a public switched telephone network (PSTN) <NUM>, the Internet <NUM>, and other networks <NUM>, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a station (STA), may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like.

Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN <NUM>, the Internet <NUM>, and/or the other networks <NUM>. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B (NB), an eNode B (eNB), a Home Node B (HNB), a Home eNode B (HeNB), a next generation Node B such as a gNode B (gNB), a new radio (NR) Node B, a site controller, an access point (AP), a personal basic service set (PBSS) control point (PCP), personal basic service set (PBSS) control point (PCP)/access point (AP), a station (STA) that is at least one of a PCP or an AP (PCP/AP), a wireless router, and the like.

The base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface <NUM> using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

The base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access, which may establish the air interface <NUM> using NR.

The base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies.

The base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE <NUM> (i.e., Wireless Fidelity (WiFi), IEEE <NUM> (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 Evolution Data Only/Evolution Data Optimized (EV-DO), Interim Standard <NUM> (IS-<NUM>), Interim Standard <NUM> (IS-<NUM>), Interim Standard <NUM> (IS-<NUM>), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

The base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell.

For example, the transmit/receive element <NUM> may be an antenna configured to transmit and/or receive RF signals. The transmit/receive element <NUM> may be configured to transmit and/or receive both RF and light signals.

Thus, the WTRU <NUM> may include two or more transmit/receive elements <NUM> (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface <NUM>.

The WTRU <NUM> may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the uplink (UL) (e.g., for transmission) and downlink (DL) (e.g., for reception) may be concurrent and/or simultaneous. The full duplex radio may include an interference management unit <NUM> to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor <NUM>). The WTRU <NUM> may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the DL (e.g., for reception)).

<FIG> is a system diagram illustrating the RAN <NUM> and the CN <NUM>.

The eNode-Bs 160a, 160b, 160c may implement MIMO technology.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AP (or equivalently an AP/PCP, which may be a station (STA) that is at least one of a PCP or an AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. 11e DLS or an <NUM>.

The primary channel may be a fixed width (e.g., <NUM> wide bandwidth) or a dynamically set width. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in <NUM> systems.

11af and <NUM>. 11af and <NUM>. 11n, and <NUM>. 11af supports <NUM>, <NUM>, and <NUM> bandwidths in the TV White Space (TVWS) spectrum, and <NUM>. 11ah may support Meter Type Control/Machine-Type Communications (MTC), such as MTC devices in a macro coverage area.

11n, <NUM>. 11ac, <NUM>. 11af, and <NUM>. If the primary channel is busy, for example, due to a STA (which supports only a <NUM> operating mode) transmitting to the AP, all available frequency bands may be considered busy even though a majority of the frequency bands remains idle.

The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing a varying number of OFDM symbols and/or lasting varying lengths of absolute time).

The CN <NUM> shown in <FIG> may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b.

For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of non-access stratum (NAS) signaling, mobility management, and the like. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, and the like. The AMF 182a/182b may provide a control plane function for switching between the RAN <NUM> and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP access technologies such as WiFi.

In view of <FIG>, and the corresponding description of <FIG>, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME <NUM>, SGW <NUM>, PGW <NUM>, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown).

To improve spectral efficiency, <NUM>. 11ac supports DL Multi-User MIMO (MU-MIMO) transmission to multiple STAs in the same symbol's time frame, for example during a DL OFDM symbol. DL MU-MIMO may also be supported by <NUM>. Since DL MU-MIMO, as it is used in <NUM>. 11ac, may use the same symbol timing for multiple STAs, then interference of the waveform transmissions to multiple STAs may not be an issue. However, in this case, all STAs involved in MU-MIMO transmission with the AP/PCP must use the same channel or band, which limits the operating bandwidth to the smallest channel bandwidth that is supported by the STA's which are included in the MU-MIMO transmission with the AP/PCP.

11ad is an amendment to the WLAN standard, which specifies the medium access control (MAC) and physical (PHY) layers for very high throughput (VHT) in the <NUM> band. Example features supported by <NUM>. 11ad include support for data rates up to <NUM> Gbits/s, and/or support for three different modulation modes including a control PHY layer with single carrier (SC) and spread spectrum, a single carrier PHY layer, and an OFDM PHY layer. 11ad may support use of the <NUM> unlicensed band, which is available globally. At <NUM>, the wavelength is <NUM>, which makes compact and antenna or antenna arrays possible. Such an antenna may create narrow RF beams at both transmitter and receiver, which effectively increase the coverage range and reduce the interference. The frame structure of <NUM>. 11ad facilitates a mechanism for beamforming training (discovery and tracking). The beamforming training protocol may include two components: a sector level sweep (SLS) procedure, and a beam refinement protocol (BRP) procedure. The SLS procedure is used for transmit beamforming training, and the BRP procedure enables receive beamforming training, and iterative refinement of both the transmit and receive beams. MIMO transmissions, including both SU-MIMO and MU-MIMO, may not be supported by <NUM>.

11ad may support multiple PHY layer protocols, such as single carrier (SC) PHY, OFDM PHY, Control PHY, low power SC PHY. All supported PHY layer protocols may share the same packet structure, though the detailed designs for each field may be different. <FIG> is an example directional multi-gigabit (DMG) physical layer convergence protocol (PLCP) protocol data unit (PPDU) packet <NUM>. The DMG PPDU packet may include, but is not limited to include, the following fields: short training field (STF) <NUM>, which may be used for automatic gain control (AGC) and/or (frequency offset) synchronization; channel estimation (CE) field <NUM>, which may be used for channel estimation and/or channel correction; header field <NUM>, which may be used for signaling; data field <NUM>, which may carry the users data payload; and/or training (TRN-R/T) subfields <NUM>, which may be used for beam refinement. Each field may have a corresponding time duration, as shown: fSTF, fCE, tHeader, tData, and/or tTRN.

<FIG> is an example beacon interval <NUM> of a DMG channel access scheme <NUM> in accordance with <NUM>. Beacon interval <NUM> may include a beacon header interval (BHI) <NUM>, and/or a data transmission interval (DTI) <NUM>. The BHI <NUM> may further include a beacon transmission interval (BTI) <NUM>, an association beamforming training (A-BFT) interval <NUM>, and/or an announcement transmission interval (ATI) <NUM>. The DTI <NUM> may include scheduled service periods (SP) <NUM> and SP <NUM>, and/or a contention-based access period (CBAP) <NUM>. Other intervals not shown may be included in beacon interval <NUM>.

The BTI <NUM> may be an access period during which one or more DMG beacon frames are transmitted. Not all DMG beacon frames are detectable by all non-PCP and non-AP STAs. Not all beacon intervals <NUM> contain a BTI <NUM>. In an example, a non-PCP STA that is also a non-AP STA may not transmit during the BTI <NUM> of the BSS of which it is a member. The A-BFT <NUM> may be an access period during which beamforming training is performed with the STA that transmitted a DMG Beacon frame during the preceding BTI <NUM>. The A-BFT <NUM> may or may not be included in the beacon interval <NUM> and its presence may be signaled in DMG beacon frames during the previous BTI <NUM>. The ATI <NUM> may be a request-response based management access period between a PCP/AP and non-PCP/non-AP STAs. The ATI <NUM> may or may not be included in the beacon interval <NUM> and its presence may be signaled in DMG beacon frames during the previous BTI <NUM>. The DTI <NUM> may be an access period during which frame exchanges are performed between STAs. There is may be one DTI <NUM> per beacon interval <NUM>, or more DTIs may be included in the beacon interval <NUM>.

Task Group ay (TGay) is expected to develop an amendment that defines standardized modifications to both the IEEE <NUM> PHY and MAC layers to enable at least one mode of operation capable of supporting a maximum throughput of at least <NUM> gigabits per second (Gbps) as measured at the MAC data service access point, while maintaining or improving the power efficiency per STA. This amendment also defines operations for license-exempt bands above <NUM> while ensuring backward compatibility and coexistence with legacy directional multi-gigabit stations (e.g., as defined by IEEE <NUM>. 11ad-<NUM> amendment) operating in the same band. Although much higher maximum throughput than that of <NUM>. 11ad is the primary goal of TGay, it is also proposed to include mobility and outdoor support. More than ten different use cases are proposed and analyzed in terms of throughput, latency, operation environment and applications. Since <NUM>. 11ay may operate in the same band as legacy standards, the new technology should ensure backward compatibility and coexistence with legacies in the same band. The highlighted two new technologies include MIMO and channel bonding.

11ay is expected to support channel bonding and channel aggregation, which involve combining two or more adjacent channels within a given frequency band to increase throughput. For example, in channel bonding (CB), two sub-channels (e.g. bandwidths <NUM> + <NUM>) may be coded as one effective channel. In channel aggregation (CA), two sub-channels may be combined but coded independently as two separate channels.

A number of elements have been included in the specification framework document (SFD) for <NUM>. For example, the SFD includes full carrier sense and physical and virtual carrier sense shall be maintained on a primary channel. The SFD additionally allows an enhanced directional multi-gigabit (EDMG) STA to transmit a frame to a peer EDMG STA to indicate intent to perform channel bonding transmission to the peer STA. This allows an EDMG STA to choose to operate over multiple channels only after receiving such a frame, thus saving power. 11ay SFD supports that, when using multiple channels, a PCP or an AP may simultaneously transmit to multiple STAs allocated to different channels individually. 11ay SFD supports allocation (scheduling) of SP(s) and scheduled CBAP(s) over more than one channel and/or over a bonded channel. These allocations do not have to include the primary channel. When allocations over different channels overlap in time, the source and destination of such allocations may be different. Channels used for such allocations may be limited to the operating channels of the BSS. Herein, "allocating" and "scheduling" may be used interchangeably with respect to SPs and CBAPs.

<FIG> is an example channelization method <NUM>, where a mix of channel bonding and channel aggregation is supported. One or more proposals consider <NUM>+<NUM> and <NUM>+<NUM> modes for channel aggregation. Channels with bandwidths of <NUM>, <NUM>,<NUM>, <NUM>,<NUM>, and <NUM>, may support single channel and/or bonded channel operations. In the example channelization method <NUM>, aggregation is shown as follows: channels <NUM>-<NUM>, each with bandwidth <NUM>, may be single, bonded and/or aggregated (e.g., aggregation between channels <NUM> and <NUM>); channels <NUM>-<NUM>, each with bandwidth <NUM>, may be single, bonded and/or aggregated (e.g., aggregation between channels <NUM> and <NUM>); channels <NUM>-<NUM>, each with bandwidth <NUM>, may be single and/or bonded (e.g., bonding between channels <NUM> and <NUM>); and channels <NUM>-<NUM>, each with bandwidth <NUM>, may be single and/or bonded (e.g., bonding between channels <NUM> and <NUM>).

The EDMG-Header-A, which is the PHY layer header for EDMG devices, may include, but is not limited to include, the following fields: a bandwidth field, a channel bonding field to differentiate between channel bonding and channel aggregation; and/or a primary channel field. These three fields may be included in the control trailer (i.e., field(s) appended to the end of a control mode PPDU to carry control information) for request to send/clear to send (RTS/CTS) setup. A duplicated RTS/CTS approach (e.g., a transmission format of the PHY layer that duplicates a <NUM> non-EDMG transmission in two or more <NUM> channels and allows a STA in a non-EDMG BSS on any one of the <NUM> channels to receive the transmission) has been proposed to carry the bandwidth information for efficient channel bonding operation.

<FIG> is an example EDMG preamble <NUM> format. The EDMG preamble <NUM> may include, but is not limited to include, the following fields: legacy STF (L-STF) <NUM> (i.e., non-EDMG STF); legacy channel estimation field (L-CEF) <NUM> (i.e., non-EDMG CEF); legacy header (L-header) field <NUM> (i.e., non-EDMG header); EDMG-Header-A field <NUM>; EDMG-STF <NUM>; EDMG-CEF <NUM>; EDMG-Header-B <NUM>; data field <NUM>; automatic gain control (AGC) field <NUM>; and/or training (TRN) field <NUM>. An EDMG preamble <NUM> format may support multi-channel transmission with MIMO, and/or multi-stream transmission of the non-EDMG part of a preamble using cyclic shifts.

<FIG> is an example multi-stream transmission scheme <NUM> of EDMG preambles over streams <NUM> and <NUM>. The example multi-stream transmission scheme <NUM> shows how the L-STF field <NUM> is constructed on a multi-channel transmission. In this example, channels <NUM> and <NUM> may be different, for example, the <NUM> sub-channels of aggregated/bonded channels. Since channels <NUM> and <NUM> are separated in the frequency domain, the information at the beginning of the header and up to the EDMG-Header-A <NUM> may be the same. In some cases, the EDMG-header-A <NUM> may be different but all other fields may be the same. The example multi-stream transmission scheme <NUM> allows non-EDMG STAs to read legacy header information (e.g., L-STF <NUM>, L-CEF <NUM>, and/or L-Header field <NUM>) and know that a bonded/aggregated EDMG transmission (EDMG-Header-A <NUM>, EDMG-STF <NUM>, and EDMG-CEF <NUM>) is coming.

The preamble <NUM>, including L-STF <NUM> and L-CEF <NUM>, may be constructed using Golay Sequences. Each sequence consists of bipolar symbols (+<NUM> or -<NUM>). These different preamble types carry basic building blocks as Golay sequences (e.g., Ga<NUM> and Gb<NUM>). Golay sequences have the useful property that their out-of-phase aperiodic autocorrelation coefficients sum to zero, which helps with synchronization.

Other EDMG-STF field and EDMG-CEF field designs may be used by TGay. <FIG> is an example EDMG-STF field <NUM> with channel bonding. In this example, the EDMG-STF field <NUM> for spatial stream "i" is built of the multiple repetitions of the GWi sequence. The GWi sequence is composed of Golay sequences, where Gwi = [GaiN, GaiN, GaiN, -GaiN] and N is the Golay sequence length (e.g., N may be equal to <NUM>, <NUM>, and <NUM> for the channel bonding (CB) = <NUM>, <NUM>, and <NUM>, respectively). A chip duration may be Tc = <NUM> nanoseconds (ns). In the example of <FIG>, the single <NUM> does not use channel bonding, and includes <NUM> x <NUM> = <NUM> samples each with size Tc/<NUM>. The <NUM> x <NUM> channel bonded channel has a channel bonding size of two with separate but adjacent channels, and includes <NUM> x <NUM> = <NUM> samples each with size Tc/<NUM>. The <NUM> x <NUM> channel bonded channel has a channel bonding size of four with separate but adjacent channels, and includes <NUM> x <NUM> = <NUM> samples each with size Tc/<NUM>.

An EDMG-Header_B field may or may not be used for MIMO transmission. A modulation and coding scheme (MCS) for EDMG-Header-B has been proposed by TGay in the case of SC PHY MU-MIMO. In an example, an EDMG-Header-B field may be transmitted using two SC symbol blocks. For each SC symbol block, part of the coded and modulated EDMG-Header-B symbols, referred to as blki for ith stream, may be carried by <NUM> chips, and a guard interval (GI) with a Golay Gai<NUM> sequence of length <NUM> chips may be appended. Thus a SC symbol block without channel bonding may be defined by the vector [Gai<NUM>, blki]. For channel bonding with <NUM>, <NUM> and <NUM> channels, the SC symbol block may be defined by matrices as shown in Equation <NUM>: <MAT>.

11ad and/or <NUM>. 11ay may consider an SC waveform that allows frequency domain equalization at the receiver. However, if there are multiple users that access the adjacent bands in the UL or if an AP serves multiple users with multiple SC waveforms operating on the adjacent bands, inter-carrier interference (ICI) may occur after the FFT operation is applied at the receiver because the various SC waveform signals may not be orthogonal to each other. For example, degradation may occur in the UL when the received signal power of the various SC waveform signals differs significantly from each other after beamforming. Thus, the embodiments disclosed herein may ensure the orthogonality in time and frequency between SC waveforms from multiple users.

Channel bonding and/or channel aggregation may not be used in <NUM>. Thus, <NUM>. 11ad may not provide a mechanism to schedule (allocate) an SP and/or a CBAP for multi-channel transmission. Moreover, with a channel bonding/aggregation transmission, more than one channel may be used for a single transmission, such that the transmission may be more vulnerable to interference from an overlapping BSS.

When a transmitting device (e.g., an AP/PCP or a non-AP/non-PCP STA) starts transmission over multiple channels, the receiving device(s) may need to know the analog/baseband beamforming scheme used, and thus corresponding receiving beams may be prepared for the transmission. The embodiments herein include design and transmission schemes for a multi-channel setup frame and multi-channel enabled transmission period that may be used to ensure that the receiving device(s) know the analog/baseband beamforming scheme used.

According to an example embodiment, in accordance with the disclosures herein, SC waveforms generated simultaneously from (or for) different STAs in the UL (or DL) may have a non-overlapping structure in the frequency domain by using a discrete Fourier transform (DFT)-spread OFDM structure. For example, <FIG> is a system diagram of an example BSS <NUM> showing how an AP <NUM> may synthesize two SC waveforms in to a single waveform (signal) <NUM> for simultaneous transmission to STAs <NUM> and <NUM>. Each STA <NUM> and <NUM> may extract its own SC waveform from the received signal <NUM>. The AP <NUM> (similarly, a PCP) may include, but is not limited to include, the following components: DFT-spread blocks <NUM><NUM> and <NUM><NUM>; windowing functions <NUM><NUM> and <NUM><NUM>; and an inverse discrete Fourier transform (IDFT) operation block <NUM>. The STA <NUM> may include, but is not limited to include, the following components: DFT-spread block <NUM><NUM>; equalizer block <NUM><NUM>; de-windowing function <NUM><NUM>; and IDFT operation block <NUM><NUM>. Similarly, STA <NUM> may include, but is not limited to include, the following components: DFT-spread block <NUM><NUM>; equalizer block <NUM><NUM>; de-windowing function <NUM><NUM>; and IDFT operation block <NUM><NUM>. Other components and functionality not shown may be included in the AP <NUM> and the STAs <NUM> and <NUM>.

The inputs u<NUM> ∈ C<NUM>x<NUM>,x<NUM> ∈ C<NUM>x<NUM> are complex numbers with respective lengths <NUM> bits and <NUM> bits (similar definitions apply to inputs u<NUM> and x<NUM>), and are transformed by the DFT-spread blocks <NUM><NUM> and <NUM><NUM>, and weighted by windowing coefficients (the widowing coefficients may not overlap) in windowing functions <NUM><NUM> and <NUM><NUM>, and provided as subcarrier indices to the IDFT block <NUM>, as shown in <FIG>.

The AP <NUM> may use DFT-spreading, via DFT-spread blocks <NUM><NUM> and <NUM><NUM>, and a frequency domain windowing operation, using windowing functions <NUM><NUM> and <NUM><NUM>, before an IDFT operation block <NUM> to synthesize two SC waveforms, intended for STA <NUM> and STA <NUM> respectively, into signal <NUM> transmitted through the antenna (or antennae). In this example, frequency domain windowing <NUM><NUM> and <NUM><NUM> may be similar to time-domain windowing, in which the first and last sample of the output of the corresponding DFT-spread block <NUM><NUM> and <NUM><NUM> is smoothed via the corresponding windowing function <NUM><NUM> and <NUM><NUM> after cyclic prefix and cyclic suffix extensions. The orthogonality between the two SC waveforms within signal <NUM> may be ensured by not overlapping the output of the frequency domain windowing operations <NUM><NUM> and <NUM><NUM> in frequency (e.g., using filter passband and a filter stopband that do not overlap). Each STA <NUM> and <NUM> may respectively process the received signal <NUM>. At the receiving end, STA <NUM> (and similarly STA <NUM>) applies DFT <NUM><NUM> to received signal <NUM>, equalization <NUM><NUM> (e.g., single tap frequency domain equalization), de-windowing <NUM><NUM> (e.g., a weighting operation and a combination operation), and IDFT <NUM><NUM> to recover the signals u<NUM>, u<NUM> and x<NUM>.

<FIG> is a system diagram of an example BSS <NUM> showing the non-overlapping structure in the UL where the STAs <NUM> and <NUM> transmit their SC waveforms <NUM><NUM> and <NUM><NUM> on adjacent channels. The AP <NUM> (similarly, a PCP) may include, but is not limited to include, the following components: IDFT operation blocks <NUM><NUM> and <NUM><NUM>; de-windowing functions <NUM><NUM> and <NUM><NUM>; equalizers <NUM><NUM> and <NUM><NUM>; and DFT-spread block <NUM>. The STA <NUM> may include, but is not limited to include, the following components: IDFT operation block <NUM><NUM>; windowing function <NUM><NUM>; and DFT-spread block <NUM><NUM>. The STA <NUM> may include, but is not limited to include, the following components: IDFT operation block <NUM><NUM>; windowing function <NUM><NUM>; and DFT-spread block <NUM><NUM>. Other components and functionality not shown may be included in the AP <NUM> and the STAs <NUM> and <NUM>. Since the inputs of the IDFT blocks <NUM><NUM> and <NUM><NUM> are not the same, the orthogonality between the signals <NUM><NUM> and <NUM><NUM> transmitted by the STAs <NUM> and <NUM> (i.e., the users) is maintained at the receiver side, which in this case is the AP <NUM>.

According to an example embodiment, in accordance with the disclosures herein, a windowing operation (e.g., windowing operations <NUM>, and <NUM><NUM> in <FIG>) may be generalized to achieve cyclic shifts in the time domain in order to achieve a cyclic delay diversity in MIMO operations. The same property may be used for achieving block-based linear shifts for SC waveforms. According to another example embodiment, the number of frequency bins (i.e., subcarriers, such that each input of a DFT corresponds to a frequency bin) between the DFT-spread blocks (e.g., DFT-spread blocks <NUM><NUM> and <NUM><NUM> in <FIG>) and the separation between the output of the frequency domain windowing operation (e.g., windowing operations <NUM><NUM> and <NUM><NUM> in <FIG>) on the transmitting side (AP or STA) may be larger than zero to allow different windowing types.

More than one design is possible for the windowing function. For example, the windowing function may be designed to have a specific structure in which the windowing achieves vestigial symmetry. This operation may allow for a low-complex receiver structure utilizing a de-windowing operation, as illustrated in the example of <FIG> is a system diagram of an example BSS <NUM> illustrating some details of the windowing and de-windowing operations. The AP <NUM> (similarly, a PCP) may include, but is not limited to include, the following components: DFT-spread blocks <NUM><NUM> and <NUM><NUM>; windowing functions <NUM><NUM> and <NUM><NUM>; and IDFT operation block <NUM>. The STA <NUM> may include, but is not limited to include, the following components: DFT-spread block <NUM>; equalizer <NUM>; de-windowing function <NUM>; and IDFT operation block <NUM>. In the example shown in <FIG>, the size of the data symbols, for example x<NUM>, x<NUM> may or may not be fixed, and the sequences u<NUM>, u<NUM> may or may not be fixed and may be adjusted depending beamforming abilities at the transmitter. In addition, the same structure may be considered to synthesize STF and CEF fields by using constant symbols instead of data symbols.

The frames <NUM>, <NUM> and <NUM> illustrate examples of how windowing works in the BSS <NUM>. At the transmitter <NUM>, output frame <NUM> of DFT block <NUM><NUM> becomes the middle of frame <NUM> after windowing function <NUM><NUM>, with added extensions on either side, where the arrows show how the extension are applied. As part of the windowing function <NUM><NUM>, the extended frame <NUM> is multiplied windowing function <NUM><NUM>, and the resulting frame is mapped to the subcarrier(s) for IDFT transformation <NUM>. At the receiver <NUM>, after DFT <NUM> and equalization <NUM>, de-windowing <NUM> is applied, as illustrated in frame <NUM>. As shown by arrows, de-windowing operation <NUM> overlaps the sidebands to the main lobe of frame <NUM>. After the de-windowing operation <NUM>, IDFT <NUM> is calculated. In another example, different windowing function than what is shown in <FIG> may be used.

According to an example embodiment, in accordance with the disclosures herein, an AP/PCP may allocate an SP and/or a CBAP in the beacon interval. An SP and CBAP scheduling and allocation procedure may be defined for communications using channel bonding/aggregation. <FIG> is a messaging diagram of an example multi-channel access and transmission procedure <NUM> with channel bonding/channel aggregation (CB/CA) over two channels, <NUM> and <NUM>, within a beacon interval <NUM>. In this example, an AP/PCP may transmit a beacon frame <NUM> (e.g., sent on the primary channel <NUM> only or in duplicated mode with a separate beacon frame <NUM> on each channel <NUM> and <NUM>), which may include at least a multi-channel SP/CBAP allocation. In an example not shown in <FIG>, the scheduling signals may be included in an announcement frame or other type of management/control frame(s) (not shown).

The AP/PCP may schedule a SP/CBAP over multiple channels where the AP/PCP may communicate with multiple STAs using the scheduled SP/CBAP. For example, with reference to <FIG>, the AP may communicate with STA1 and STA2 during SP <NUM>. The AP/PCP may schedule a SP/CBAP over multiple channels where each respective channel may be allocated to a pair of transmit and receive (Tx/Rx) STAs. For example, the AP may communicate with STA3 and STA4 over channel <NUM>, and with STA5 and STA6 over channel <NUM> during SP <NUM>, respectively. The AP/PCP may schedule a SP/CBAP over multiple channels where the AP/PCP may communicate with one STA using this SP/CBAP. For example, with reference to <FIG>, the AP may communicate with STA7 over channels <NUM> and <NUM> during SP <NUM>. The AP/PCP may schedule a SP/CBAP over one or more channel(s) (e.g., a subset of the channels) where the AP/PCP may communicate with one or more STAs, or allow for contention-based access, as shown in CBAP <NUM> and CBAP <NUM>. Channel <NUM> in CBAP <NUM>, labeled "empty", may not be used for contention in the BSS (e.g., due to OBSS activity).

Example principles for multi-channel scheduling in a beacon interval include the following, in accordance with the disclosures herein. In an example, the AP/PCP may allocate SP/CBAPs over more than one channel using either channel bonding/aggregation. In another example, the AP/PCP may allocate SP for multi-channel multi-user transmission; for example, the AP may use the SP to communicate with multiple STAs where each STA may be allocated to one channel (e.g., an exclusive channel per STA). In another example, the AP/PCP may allocate SP for multi-channel multi-user transmission. For example, the AP may use the SP to communicate with multiple STAs where each STA may be allocated to a channel, which may be shared (e.g., using MU-MIMO transmission) for simultaneous transmission and/or reception (UL and/or DL) with two or more STAs.

In order to mitigate inter-BSS interference during a SP and/or a CBAP, the AP/PCP may coordinate with a neighboring overlapping BSS (OBSS) (i.e., a BSS with a coverage area that overlaps with the coverage area of the BSS), and allocate the SPs to its STAs accordingly. In this way, the AP/PCP may monitor the beacon frames and/or the announcement frames from OBSS AP/PCPs.

In another example, all the STAs (in the BSS) may monitor all of the beacon frames, including the beacon frames transmitted from an OBSS AP/PCP. A non-AP STA that overheard (received) beacon frame(s) from an OBSS AP/PCP may, in some cases, report the received information to its associated AP/PCP (in the same BSS). In an example scenario, if the associated AP/PCP may send a message requesting non-AP STAs in its BSS to report OBSS scheduling information. In another example, the associated AP/PCP may include a list of OBSS AP/PCPs from which the associated AP/PCP may monitor/receive/hear the beacon frames. In this case, the non-AP STAs may report information from AP/PCPs which are not on the list. In another example, the AP/PCP may indicate its capability of monitoring OBSS beacon transmissions in its own beacon frame, or any other type of management frame. In this case, the associated non-AP STAs may indicate its capability of monitoring OBSS beacon transmissions in its capability field of an association frame or any other type of management frame. The STAs, including both AP/PCP STAs and non-AP STAs, may monitor the beacon frames which may be transmitted from AP/PCP which may have a capability field set.

In an example, the allocation (scheduling) of SPs in a BSS may avoid the allocated SPs in another BSS (e.g., an OBSS). For example, the AP/PCP may notice another AP/PCP (e.g., in an OBSS) assigns an SP starting from time t<NUM> with duration T. In an example, the AP/PCP may treat a scheduled OBSS SP differently from a scheduled OBSS CBAP. For example, the AP/PCP may not allocate anything if an OBSS SP is present. If an OBSS CBAP is present, the AP/PCP may try to allocate other non-overlapping/non-occupied time/frequency slot(s) first. If no non-overlapping/non-occupied time/frequency slot are available, the AP/PCP may allocate the CBAP occupied time/frequency slot. In an example, the AP/PCP may allocate a CBAP during the occupied OBSS CBAP.

Based on the property of this SP or CBAP assignment (allocation), the AP/PCP may assign multi-channel transmissions using any of one or more of the following methods. For a channel (e.g., a first channel) that may not be interfered by the OBSS transmission, the AP/PCP may allocate that channel to its associated STAs. The allocation may be for a SP and/or a CBAP. For a channel (e.g., a second channel) that is overlapping with the OBSS and has been allocated, the AP/PCP may not allocate corresponding time blocks (e.g., leave the corresponding time blocks empty) so that the corresponding time blocks may be used by the OBSS STAs. For a channel (e.g., a third channel) that is overlapping with the OBSS and has been allocated, the AP/PCP may allocate corresponding time blocks on the channel that may also be used by the OBSS STAs. In this case, the AP/PCP may include a field to indicate the time blocks may be used by the OBSS STAs in the allocation signaling (e.g., in an extended schedule element, a dynamic allocation information field, a modified extended schedule element, and/or a modified dynamic allocation information field control trailer field). Additionally, the AP/PCP may include more fields in the SP/CBAP allocation to indicate the usage of the OBSS STA, including, but not limited to, the following example fields: SP allocation; CBAP allocation; a truncate indicator field to indicate whether the allocation is able to be truncated; an extendable indicator field to indicate whether the allocation is extendable; and/or an indicator field to indicate whether the allocation is dynamic. Thus the STAs may be protected by specific protection mechanisms while perform transmission on the allocated time block on the channel. Examples of protection mechanisms, include, but are not limited to, the following mechanism: carrier-sensing (e.g., carrier-sensing multiple access (CSMA)); virtual carrier-sensing; and/or an RTS/CTS procedure.

According to an example embodiment, in accordance with the disclosures herein, a group allocation mechanism may be used to mitigate the OBSS interference. For example, the AP/PCP may group SPs/CBAPs with certain properties into pre-defined periods, which may be referred to as allocation group periods (AGPs). For example, the AP/PCP may group SPs/CBAPs with similar channel bonding/aggregation properties into one or more AGPs, such that each AGP may include one or more SPs and/or CBAPs. For example, the AP/PCP may group SPs/CBAPs using CB/CA in one or more AGPs, group SPs/CBAPs without CB/CA in one or more other (different) AGPs. A beacon interval may include one or more AGPs.

<FIG> is a messaging diagram of an example multi-channel access and transmissions procedure <NUM> using multiple AGPs <NUM>, <NUM>, <NUM>, and <NUM> during beacon interval <NUM>. CB/CA may or may not be used over channels <NUM> and <NUM> in different AGPs. For example, in AGP <NUM>, the AP/PCP may allocate/schedule SPs <NUM>, <NUM> and <NUM> for CB/CA transmission. In this example, the AP/PCP may communicate with STA1 and STA2 in SP <NUM>, and with STA3, STA4, STA5, and STA6 in SP <NUM>, and with STA7 in SP <NUM>. In AGP <NUM>, the AP/PCP may allocate/schedule CBAPs for CB/CA transmission using channels <NUM> and <NUM>. In AGP <NUM>, the AP/PCP may allocate/schedule SPs/CBAPs to transmit over channel <NUM> (e.g., channel <NUM> may be the primary channel) while not allocating transmission over channel <NUM> and thus not using CB/CA. In this example, during AGP <NUM>, the AP/PCP may communicate on channel <NUM> with STA10 in SP <NUM>, and STA11 and STA12 in SP <NUM>, and STA13 in SP <NUM>. In AGP <NUM>, the AP/PCP may allocate/schedule SPs/CBAPs to transmit over channel <NUM> (e.g., channel <NUM> may be a secondary channel) while not using channel <NUM> and thus not using CB/CA. In this example, in AGP <NUM> channel <NUM> may be used for CBAP. In this way, AGP <NUM> and AGP <NUM> may be shared with neighboring OBSS transmissions. For example, the OBSS AP/PCP may allocate/schedule AGPs using the empty channel (e.g., channel <NUM> in AGP <NUM> and channel <NUM> in AGP <NUM>).

According to an example embodiment, in accordance with the disclosures herein, an AP/PCP may use hierarchical signaling to indicate the AGP and/or SP/CBAP scheduling. The hierarchical scheduling information may be carried in a control frame, such as a beacon frame, an announcement frame or any other type of control or management frames. The hierarchical signaling may be used to enable multi-channel multi-user transmission over the SP/CBAPs. The hierarchical signaling may be used to enable MIMO transmission over the SP/CBAPs.

SPs/CBAPs in each AGP may share one or more common properties such as CB/CA properties, and thus a common signaling field may be used to indicate the common properties for the periods scheduled in an AGP. Thus, the common information may not need to be repeated, which reduces the signaling overhead. In an exmaple, a common information field may indicate the number of individual allocations in the AGP. An individual SP/CBAP allocation field may be signaled for each SP/CBAP in an AGP and may carry specific information for the respective SP/CBAP.

<FIG> is an example hierarchical signaling element (or frame) <NUM> for group allocation using AGP for multi-channel access and transmission. The hierarchical signaling element <NUM> may be carried, for example, in a beacon frame, an announcement frame or other type of control/management frame. The hierarchical signaling element <NUM> may include, but is not limited to include, any of the following fields: an element identification (ID) field <NUM>, which may be used to indicate the hierarchical allocation/schedule signaling; a length field <NUM>, which may be used to indicate the length of the hierarchical signaling element <NUM>; and/or AGP fields <NUM><NUM>. <NUM>n for the n AGP groups, which may carry information about the respective AGP groups. The example shown in <FIG> (and <FIG>) shows signaling using an information element (IE)-type format, however the disclosed fields and solutions may be used in formats other than IEs, such as extension fields. For example, if extension field format is used, then the element ID field <NUM> and/or the length field <NUM> may not be used.

Each AGP field <NUM><NUM>. <NUM>n may include subfields, as illustrated for AGP <NUM><NUM>. For example, AGP field <NUM><NUM> may include a common information field <NUM>, which may carry common information shared by the SPs/CBAPs in the corresponding AGP. Multiple examples of common information that may be included in the common information field <NUM> are given in following. For example, the common information field <NUM> may include channel information (e.g., one or more channel information fields). Examples of such channel information may include, but is not limited, any one or more of the following fields (not shown): a CB/CA field, which may be used to indicate whether channel bonding, and/or channel aggregation is allowed; a multi-channel multi-user field, which may be used to indicate whether multi-user transmission is supported; a maximum operation bandwidth field, which may be used to indicate the maximum allowed operation channel bandwidth; and/or a channel allocation information field, which may be used to indicate which channel or channels may be allocated to the AGP (e.g., a channel index or a channel index bitmap may be used to indicate the channel allocation).

The common information field <NUM> may carry an SP/CBAP field, which may indicate whether the AGP include SPs, or CBAPs or a mix of SPs and CBAPs; a number of allocations in the AGP; an allocation properties field which may be used to indicate whether the allocations in the AGP are pseudo static, able to be truncated, extendable, PCP/AP active. The common information field <NUM> may carry an interference field, which may indicate whether interference is in the AGP (examples of interference include OBSS interference and/or interference from spatial sharing transmission within the same BSS). In an example, the AP/PCP may set the interference field if the AP/PCP detects the OBSS beacon or announcement frames (which may carry SP/CBAP assignment) transmitted by the OBSS AP/PCP on the channels by the OBSS. In the case that CB/CA is used, the interference field may be used to indicate the interference condition on each channel.

The common information field <NUM> may carry a spatial sharing field, which may indicate whether spatial sharing operation is allowed or not. Spatial sharing may be performed over the channel(s) indicated in channel information field. The spatial sharing field may indicate whether spatial sharing is allowed on each channel. Spatial sharing may refer to transmissions between two pairs of transmitters and receivers within one BSS or in different BSS (e.g., STA1 and STA2 may communicate using an SP or CBAP, while STA3 and STA4 may communicate using the same time slot, where STA1, STA2, STA3, and STA4 belong to one or more BSSs).

The common information field <NUM> may carry a MIMO field, which indicate whether MIMO transmission are allowed or not. The MIMO field may include subfields to indicate whether SU-MIMO and/or MU-MIMO are allowed. The MIMO transmission may be performed over the channel(s) indicated in channel information field, and/or the MIMO field may indicate whether MIMO (or SU-MIMO and MU-MIMO) is allowed on each channel.

The common information field <NUM> may carry a beamforming training field, which may indicate whether beamforming training is allowed or not. The beamforming training field may indicate the SPs/CBAPs in the AGP that are dedicated for or include beamforming training and feedback frames. The beamforming training may be performed over the channel(s) indicated in channel information field, or the beamforming training field may indicate whether beamforming training is allowed on each channel. The beamforming training SPs/CBAPs may sweep using multiple beams, and thus may introduce more interference to neighboring transmissions. In the case that beamforming training field is set, the OBSS AP/PCP and STAs may expect interference and/or beam sweep on the assigned channel(s).

The common information field <NUM> may carry a multi-user field, which may indicate whether multi-user transmission is allowed or not.

Another subfield of AGP field <NUM><NUM> may be an individual SP/CBAP field <NUM>, which may carry allocation information fields <NUM><NUM>. <NUM>m for each individual SP/CBAP allocation (there are m SP/CBAP allocations in this example). For example, the individual SP/CBAP field <NUM> may carry, for each allocation in its respective allocation fields <NUM><NUM>. <NUM>m, any one or more of the following information: allocation start information; allocation block duration; a number of blocks for the allocation; an allocation block period; and/or an allocation duration. A detailed example of an allocation information fields <NUM><NUM>. <NUM>m is shown in <FIG>. Moreover, some fields that may be included in the common information field <NUM> may be carried by the individual SP/CBAP information fields <NUM>, for example in the case that the corresponding AGP may allow different settings on the corresponding field.

<FIG> is an example allocation information field <NUM> that may be included in a hierarchical signaling element for group allocation using AGP for multi-channel access and transmission. The example allocation information field <NUM> may include, but is not limited to include, any of the following fields: an allocation ID field <NUM> identifying the SP/CBAP allocation; one or more source association identifier (AID) fields <NUM> (may depend on the properties indicated in the common field); on or more destination AID fields <NUM>, (may depend on the properties indicated in the common field); an allocation start time field <NUM>; an allocation block duration field <NUM>; an number of blocks field <NUM>; and/or an allocation block period field <NUM>. In an example, one source AID and one destination AID may be included in each allocation information field <NUM>. In the case of MU-MIMO transmission and multi-channel multi-user transmission, more than one allocation may be defined for the same time slot.

According to an example embodiment, in accordance with the disclosures herein, a backward compatible allocation signaling scheme may be used for multi-channel access and transmission. An extended schedule information element (IE) may be used to carry SP/CBAP scheduling information, and may be extended to signal additional information. In order to maintain backward compatibility (e.g., with <NUM>. 11ad), the reserved bits and/or bits not fully used in an extended schedule IE may be used to carry additional information. In this way, only limited information may be carried using the extended schedule IE.

<FIG> is an example static allocation signaling element (or frame) <NUM> that includes multi-channel information. The static allocation signaling element <NUM> may include, but is not limited to include, any one or more of the following fields: element ID field <NUM>; length field <NUM>; and/or allocation fields <NUM><NUM>. <NUM>n for each individual SP/CBAP allocation (there are n SP/CBAP allocations in this example). Each allocation field <NUM><NUM>. <NUM>n may include, but is not limited to include, any one or more of the following fields: allocation control field <NUM>; beamforming (BF) control field <NUM>; source AID field <NUM>; destination AID field <NUM>; allocation start time field <NUM>; allocation block duration field <NUM>; number of blocks field <NUM>; and/or allocation block period <NUM>. The allocation control field <NUM> may include, but is not limited to include, any one or more of the following fields: allocation ID field <NUM>; allocation type field <NUM>; pseudo-static field <NUM>; truncate indicator field <NUM>; extendable indicator field <NUM>; PCP active field <NUM> may indicate that the PCP is available to transmit or receive during the CBAP or SP; lower-power (LP) SC indicator field <NUM> may be used to indicate that low-power SC mode is used (e.g., single bit); and/or a reserved field <NUM>.

In an example, any of the BF control field <NUM>, the allocation type field <NUM>, and/or the reserved field <NUM>, which may be not fully used in legacy systems, may be modified to carry more multi-channel related information, including, but not limited to, the following subfields (not shown): a MIMO field; CB/CA field; multi-user field; and/or a spatial sharing field. For example, the MIMO field may indicate whether MIMO transmission is allowed or not. The MIMO field may further include two subfields to indicate whether SU-MIMO and MU-MIMO are allowed. The MIMO transmission may be performed over the channel(s) indicated in a channel information field, or the MIMO field may indicate whether MIMO (or SU-MIMO and MU-MIMO) is allowed on each channel. The CB/CA field may indicate whether channel bonding and/or channel aggregation is allowed, and the multi-user field may indicate whether multi-user transmissions are allowed or not. In the case that an AGP may include one allocation, a common information field and an individual SP/CBAP information field may be used together to carry information for a single allocation.

The spatial sharing field may indicate whether a spatial sharing operation is allowed or not. Spatial sharing may be performed over the bonded/aggregated channels. The spatial sharing field may indicate whether spatial sharing is allowed on each channel. Spatial sharing may refer transmissions between two pairs of transmitters and receivers within one BSS or in different BSS (e.g., STA1 and STA2 may communicate using a SP or CBAP, while STA3 and STA4 may communicate and using the same time slot, where STA1, STA2, STA3 and STA4 may belong to one or more BSSs).

According to another example embodiment, in accordance with the disclosures herein, a backward compatible allocation signaling scheme may be used for multi-channel access and transmission. A dynamic allocation information field may be used to allocate channel access during scheduled SPs and CBAPs. For example, the dynamic allocation information field may be carried in a service period request (SPR) frame, a grant frame and/or any other type of control/management frames. In order to maintain backward compatibility, the multi-channel multi-user information, and/or MIMO information may be carried in a control trailer that may be appended at the end of the frame which carries the dynamic allocation information field.

<FIG> is an example control frame <NUM> carrying multi-channel multi-user related information. The control frame <NUM> may include, but is not limited to include, any one or more of the following elements (fields): L-STF <NUM>; L-CEF <NUM>; L-header field <NUM>; MAC frame <NUM>; and/or trailer <NUM>. The MAC frame <NUM>, which may be backwards compatible with older <NUM> releases, may include, in addition to standard or legacy MAC IEs (not shown), a dynamic allocation information field <NUM>. The dynamic allocation information field <NUM> may include, but is not limited to include, any one or more of the following fields: traffic identifier (TID) field <NUM>; allocation type field <NUM>; source AID field <NUM>; destination AID field <NUM>; allocation duration field <NUM>; and/or reserved field <NUM>.

The control trailer <NUM> may include more information about the allocation. For example, some bits of the reserved field <NUM> in the dynamic allocation information field <NUM> may be used to indicate that more allocation information is carried in the control trailer <NUM>. The control trailer field <NUM> may include, but is not limited to include, any one or more of the following fields: a trailer type field <NUM>; a MIMO field <NUM>; a CB/CA field <NUM>; a multi-user field <NUM>; and/or a spatial sharing field <NUM>. The trailer type field <NUM> may indicate the type of the control trailer <NUM>. For example, the control trailer type may be an RTS/CTS extension, or a dynamic allocation extension.

The MIMO field <NUM> may indicate whether MIMO transmission is allowed or not. The MIMO field <NUM> may include two subfields (not shown) to indicate whether SU-MIMO and MU-MIMO are allowed. The MIMO transmission may be performed over the channel(s) indicated in a channel information field (not shown). The MIMO field <NUM> may indicate whether MIMO (or SU-MIMO and/or MU-MIMO), is allowed on each channel. The CB/CA field <NUM> may indicate whether channel bonding, and/or channel aggregation is allowed. The multi-user field <NUM> may indicate whether multi-user transmission is allowed or not. The spatial sharing field <NUM> may indicate whether a spatial sharing operation is allowed or not. The spatial sharing may be performed over the bonded/aggregated channels. The spatial sharing field <NUM> may indicate whether spatial sharing is allowed on each channel. Spatial sharing may refer to transmissions between two pairs of transmitters and receivers within one BSS or in different BSS.

According to another example embodiment, in accordance with the disclosures herein, a multi-channel transmission setup frame may be used to setup the Tx/Rx beam pairs on multiple channels. In an example, the setup frame may be omitted when one or more of following conditions are met: the transmission is a single-user single data stream transmission using beams trained on a primary channel and/or a bonded/aggregated channel in which a transmitter and receiver may know the corresponding Tx/Rx beams (thus, setup may not be needed); and/or the transmission uses default Tx/Rx antenna beams and/or analog beams. In an example, the setup frame may be used when one or more of following conditions are met: more analog beams may be used in the multi-channel transmission; or multi-channel multi-user transmission may be performed, for example, in the case that an PCP/AP may transmit simultaneously to multiple users.

<FIG> is a signaling diagram of an example channel access procedure <NUM> for multi-channel (MC) transmission using a MC setup frame <NUM>. In this example, an AP/PCP <NUM> communicates with STAs <NUM> and <NUM>, which may be part of the same BSS. The AP/PCP <NUM> may schedule one or more SPs and/or CBAPs for multi-channel transmission by including scheduling information in a beacon frame <NUM> (e.g., sent on the primary channel <NUM> only, or on all channels <NUM> and <NUM> using duplicated mode), for example to schedule SP/CBAP <NUM>. The AP/PCP <NUM> may decide whether or not to transmit the MC setup frame <NUM>. If transmitted, the MC setup frame <NUM> may be transmitted in the scheduled SP/CBAP <NUM> (e.g., a first transmission in the SP/CBAP <NUM>). In the case that the MC setup frame <NUM> is transmitted, the MC setup frame <NUM> may include, but is not limited to include, any of the following fields (not shown): a frame purpose/type field, which may indicate that the frame <NUM> is an MC setup frame; one or more receiving address (RA) fields (e.g., multiple RA fields may be used for the multi-user transmission case), such that in the case of multi-channel multi-user transmission, a broadcast or multicast address may be indicated by the RA field(s); and/or a user specific information field.

A user specific information field in the MC setup frame <NUM> may include, but is not limited to include, any of the following fields (not shown): an AID field; an channel assignment field; an analog beam assignment field; and/or a digital/baseband precoding scheme field.

The AID field may indicate the AID or compressed/partial AID of the STA (user). The channel assignment field may indicate the channel assigned to the STA (user). A channel index may be used for the signaling, and/or the bonded/aggregated channels may be numbered in predetermined order and the numbering may be included in the signaling. For example, the bonded/aggregated channels may be numbered in descending or ascending order based on the central frequency or the channel index.

The user specific information field may include an analog beam assignment field including, for example, an antenna index, polarization information, and/or a beam/sector index, which may be used to uniquely define an analog beam on the assigned channel(s). In the case that more than one channel is assigned to a STA (user) and different beams may be applied to different channels, the analog beam assignment may carry beam/antenna/polarization etc. information for each channel.

The digital/baseband precoding scheme information may be used to specify detailed precoding scheme on the assigned channel(s). In the case that more than one channel is assigned to a STA (user), different precoding schemes may be allowed to be applied to different channel, and the digital/baseband precoding scheme information may accordingly be signaled per channel.

Intended STAs employing MC setup procedure and thus able to receive the MC setup frame <NUM> may respond to the MC setup frame <NUM> by sending response frames to the AP/PCP <NUM>. For example, two (or) more response frames <NUM> may be transmitted concurrently by STA <NUM> using different frequency channels <NUM> and <NUM>, where the channels <NUM> and <NUM> may be assigned to STA <NUM> by the AP/PCP <NUM> in the MC setup frame <NUM>. Similarly, STA <NUM> may send response frames <NUM> concurrently over channels <NUM> and <NUM>, where the channels <NUM> and <NUM> may be assigned to STA <NUM> by the AP/PCP <NUM> in the MC setup frame <NUM>. The channels <NUM> and <NUM> used by STA <NUM> may be the same or different than the channels <NUM> and <NUM> used for STA <NUM>, such that any of the channels may be primary or secondary channels, and two or more channels may be combined using channel aggregation and/or channel bonding. In other examples, not shown, response frames may be sent concurrently using different spatial domain beams/weights, or sequentially in different time slots. A response frame <NUM> and/ or <NUM> may be polled or scheduled; in the case with polling, a first response frame may be transmitted without polling. The transmission of response frames may be performed by quasiomni transmission or directional transmission. In an example, the response frames may not be transmitted and may be omitted for overhead reduction.

MC setup frame <NUM>, poll frames <NUM> and <NUM>, and ACK/BA frames <NUM> and <NUM> are control frames, which may be transmitted over a primary channel, an assigned channel, or combined channels using channel bonding/aggregation. The AP/PCP <NUM> may perform MC transmission by transmitting MU frame <NUM> after receiving the response frame(s) (e.g., response frames <NUM> and/or <NUM>). The MU frame <NUM> may be a data frame, and may be transmitted to STA <NUM> on a channel (or combined channel) assigned to STA <NUM>, and to STA <NUM> on a channel (or combined channel) assigned. The AP/PCP <NUM> may wait an inter-frame space (xIFS) time duration after reception of the response frame <NUM> before performing MC transmission. The MC transmission may be directional using the beams and precoding schemes set by the MC setup frame <NUM>. In the case where the response frame is omitted, the MC transmission may be performed xIFS time after the transmission of MC setup frame <NUM>. In the case the response frame is not omitted, the AP/PCP <NUM> may not detect all of the response frames <NUM> and <NUM>. In this case, the AP/PCP <NUM> may transmit to the STAs <NUM> and <NUM> from which the response frame(s) <NUM> and <NUM> may be successfully detected or the AP/PCP <NUM> may transmit a control frame (not shown) to terminate the SP/CBAP <NUM>.

Intended STAs <NUM> and <NUM> may send ACK/BA frames <NUM> and <NUM>, respectively back to the AP/PCP <NUM> to acknowledge successful reception of the MC transmission(s). The ACK/BA frames <NUM> and <NUM> may be transmitted using directional transmission. In an example, ACK/BA frames <NUM> may be transmitted by STA <NUM> concurrently using different frequency channels <NUM> and <NUM>, where the channels <NUM> and <NUM> may be assigned by the AP/PCP <NUM> in the MC setup frame <NUM>. In other examples, not shown, ACK/BA frames may be sent by STAs concurrently using different spatial domain beams/weights, or sequentially in a different time slots. An ACK/BA frame may be polled or scheduled; in the case of polling, the first ACK/BA frame may be transmitted without polling.

<FIG> is a flow diagram of an example multi-channel scheduling (allocation) procedure <NUM> for scheduling PSs/CBAPs performed by an AP/PCP. At <NUM>, the AP/PCP may monitor for beacon frames and announcement frames transmitted by at least one other access AP/PCP associated with at least one OBSS. The monitored beacon frames and announcement frames may include SP/CBAP scheduling information for the OBSS. At <NUM>, the AP/PCP may generate an allocation of SP/CBAP (one or more SPs/CBAPs) over multiple channels to be used in a beacon interval taking into account the SP scheduling information for the OBSS. At <NUM>, the AP/PCP may transmit a beacon frame (or announcement frame) to STA(s) (WTRUs) in its BSS including the allocation of the SP/CBAP.

Claim 1:
An access point, AP (<NUM>), that is part of a basic service set, BSS, and configured to provide multi-channel, MC, access to at least one station, STA (<NUM>), in the BSS, the AP comprising:
a receiver configured to receive at least a first beacon frame from at least one other access point/personal basic service set, PBSS, control point, AP/PCP, associated with at least one overlapping basic service set, OBSS, wherein the first beacon frame includes at least service period, SP scheduling information for the OBSS; and
a transmitter and a processor configured to transmit a second beacon frame to the at least one STA in the BSS, wherein the second beacon frame includes information indicating an allocated at least one SP associated with the BSS on at least two channels to be used in the BSS in a beacon interval, wherein the at least one SP on the at least two channels is allocated by the AP at least in part based on the SP scheduling information for the OBSS.