WO2018222177A1

WO2018222177A1 - Methods and arrangements for collaborative beamforming in multi-access point wi-fi networks

Info

Publication number: WO2018222177A1
Application number: PCT/US2017/035099
Authority: WO
Inventors: Roya Doostnejad; Thomas J. Kenney
Original assignee: Intel Corporation
Priority date: 2017-05-31
Filing date: 2017-05-31
Publication date: 2018-12-06

Abstract

Logic may beamform a set of collaborative access points (C-APs) to facilitate spatial reuse. Logic may transmit a collaborative beamforming (CBF) announcement to initiate CBF and to inform the stations of the order of channel sounding by and identifiers for access points (APs) in the set. Logic may transmit channel sounding and receive one or more feedback reports in response. Logic may transmit one or more report polls to trigger the feedback reports from the remaining stations associated with the set. Logic may request more extensive channel information from primary stations associated with an AP and less extensive channel information from secondary stations associated with the AP. Logic may transmit channel information from each AP in the set for each primary and secondary station. Logic may transmit the channel information to a central server to schedule simultaneous transmissions between multiple APs and multiple primary stations on a channel.

Description

METHODS AND ARRANGEMENTS FOR COLLABORATIVE BEAMFORMING IN

MULTI-ACCESS POINT WI-FI NETWORKS

TECHNICAL FIELD

Embodiments are in the field of wireless communications. More particularly, embodiments may beamform access points (APs) in Wi-Fi (wireless fidelity) networks to facilitate spatial reuse.

BACKGROUND

A wireless communications system may use bi-directional signaling in areas with a high density of users with mobile and static devices and with a high demand for higher wireless data rates such as training centers, conference halls, and stadiums. To support such environments, many APs are located within a given area to service more Wi-Fi devices. Current Wi-Fi only allows one AP to communicate with a station at a time on a channel. Access time to that channel is divided between the links which reduces throughput, increases latency, and reduces link reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of a wireless network for collaborative beamforming (CBF);

FIG. 2A depicts an embodiment of a timing diagram for CBF;

FIG. 2B depicts an alternative embodiment of a timing diagram for CBF;

FIG. 2C depicts an embodiment of transmissions between four stations and an AP;

FIG. 2D depicts an embodiment of a transmission between one station and an AP;

FIG. 2E depicts an embodiment of resource units in a 20 Megahertz (MHz) bandwidth;

FIG. 2F depicts an embodiment of a CBF announcement frame;

FIG. 2G depicts an embodiment of a station information field in a CBF announcement frame;

FIG. 2H depicts an embodiment of a partial bandwidth field in a station information field;

FIG. 21 depicts an embodiment of a channel sounding packet;

FIG. 2J depicts an embodiment of a beamforming report poll;

FIG. 2K depicts an embodiment of a beamforming feedback report;

FIG. 2L depicts an embodiment of a control field of a beamforming feedback report;

FIG. 3 depicts an embodiment of a system for CBF;

FIG. 4 depicts an embodiment of an apparatus to beamform for CBF;

FIG. 5A depicts an embodiment of a flowchart for an AP to beamform for CBF;

FIG. 5B depicts an embodiment of a flowchart for a station for CBF; FIG. 6 depicts an embodiment of a flowchart of a central server for CBF;

FIG. 7 depicts an embodiment of a flowchart for collaborative APs to transmit to

stations simultaneously on the same channel;

DETAILED DESCRIPTION OF EMBODIMENTS

The following is a detailed description of embodiments depicted in the drawings. The detailed description covers all modifications, equivalents, and alternatives falling within the appended claims.

Embodiments may improve current Wi-Fi (wireless fidelity) standards by enabling mechanisms to allow benefit from additional Access Points (APs) operating in the same channel at the same time. Even though several channels are available, if the deployment is dense, the channels should be shared to increase data throughput. However, there is currently no technique for centralized interference alignment between multiple APs.

Embodiments may enable centralized interference alignment between multiple APs for spatial reuse (SR), facilitating multiple AP transmissions at the same time and on the same sets or overlapping sets of subcarriers of the channel. Many embodiments implement collaborative beamforming (CBF) to facilitate SR with channel directionality, transmission power management, and scheduling to manage interference from other devices operating concurrently on the channel.

Several embodiments include a central backhaul controller referred to herein as a central server. The central server may be wired to, or wirelessly connected to, a set of collaborative APs (C- APs) to enable exchanges of information among C-APs and a central server for CBF. In other embodiments, one or more of the C-APs may incorporate functionality of the central server.

In many embodiments, the central server may schedule transmissions between APs in the set of C-APs and stations associated with the APs based on the channel interference caused, by other C- APs in the set, at the stations; directivity of the channels between the C-AP's and their primary and secondary stations; and, in some embodiments, interference caused, by the stations, at the C-APs. The C-APs and the stations may manage channel interference by static transmission power adjustments or dynamic transmission power adjustments while operating in an SR mode.

In some embodiments, a network operator or a central server may define a candidate set of C- APs based on one or more of several potential factors such as on a geographical location of stations and APs, quality of service (QoS) requirements for specific stations, and/or any other criterion specific to the network. Each station may associate with each of the APs in the set of C-APs. The AP, station, or central server may define one primary AP and a set of secondary APs for each station based on, e.g., a Signal-to-Noise ratio (S R) or other signal strength indicator for the station.

In several embodiments, a group of stations may associate with the same primary AP. Such stations may be referred to as primary stations for that AP and secondary stations for all other APs in the set of C-APs. The secondary set of APs associated with each station may include all APs in the set of C-APs that can be sensed at the station or, in some embodiments, all other APs in the set.

In some embodiments, the APs can generate and transmit a collaborative beamforming (CBF) announcement to initiate CBF, to identify the identifier (ID) for each AP in the C-AP set, to identify the ordering of C-APs and stations for channel sounding, and to identify which stations are primary to each AP in the set of C-APs. The CBF announcement may also communicate to the stations the details of the beamforming (BF) feedback reports. Each of the APs in the set of C-APs may transmit training fields for channel sounding in accordance with the ordering of C-APs for channel sounding.

After receiving the CBF announcement, every station is informed on C-APs set and will expect to receive channel sounding from the C-AP set in the order specified in the CBF announcement one by one in a time division multiple access (TDMA) procedure. The CBF announcement may initiate the collaborative channel sounding procedure at the APs as well. In several embodiments, bidirectional BF may occur between an AP and the AP's primary stations.

The APs may be capable of channel sounding and receiving BF feedback reports from the stations in a TDMA procedure. In several embodiments, each AP may instruct one or more groups of primary stations and secondary stations to simultaneously transmit BF feedback reports using Orthogonal Frequency-Division Multiple Access (OFDMA) in uplink transmissions to reduce the training overhead and latency. Such embodiments may measure the channels from all APs in the set of C-APs to all candidate stations (both primary and secondary stations) and all candidate stations may transmit the BF feedback reports to each AP and the central server.

Embodiments may increase SR of Wi-Fi communications with multiple different bandwidths at different frequency bands. Many embodiments focus on bands between 1 Gigahertz (GHz) and 6 GHz. Some embodiments focus on bandwidths such as 20 Megahertz (MHz), 40 MHz, 80 MHz, 160 MHz, and 80+80 MHz, while other embodiments focus on other bandwidths in the same or other frequency bands. However, the embodiments are not limited to the bandwidths and frequency bands described herein.

Various embodiments may be designed to address different technical problems associated with sharing a channel in areas with, e.g., a high density of wireless devices and, e.g., a high data throughput demand. Other technical problems may include facilitation of SR in dense Wi-Fi environments, BF to facilitate SR in dense Wi-Fi environments, facilitation of SR with simplified processing relative to processing required for joint BF and joint transmissions by multiple APs to the same station, reduction in bandwidth required for BF, communicating and determining an order for BF feedback reports, communicating and determining an order for APs to sound a channel, communicating and determining one or more BF feedback report types, and/or the like.

Different technical problems such as those discussed above may be addressed by one or more different embodiments. For instance, some embodiments that address sharing a channel in areas with, e.g., a high density of wireless devices and, e.g., a high data throughput demand may do so by one or more different technical means such as transmitting, by each of the APs of the set, or receiving by a station of a group of stations, a collaborative BF (CBF) announcement frame sequentially in accordance with a predetermined sequence for the set, wherein the CBF announcement frame is addressed to a group of stations and describes the order of channel sounding by a set of C-APs and an order of response to the channel sounding by stations associated with the set; transmitting, by each of the APs of the set, or receiving by each station of a group of stations, a channel sounding packet; transmitting to each station, or receiving by a station of a group of stations, a BF report poll to initiate transmission of the BF feedback report from each station; and receiving, by each of the APs, after transmitting the channel sounding packet, or transmitting by each of the stations, a BF feedback report from each of the stations prior to a subsequent AP of the set, according to the predetermined sequence, transmitting the CBF announcement frame.

Some embodiments are particularly directed to improvements for wireless local area network (WLAN), such as a WLAN implementing one or more Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (sometimes collectively referred to as "Wi-Fi", or wireless fidelity). Such standards may include, for instance, the IEEE 802.11-2016, published March 29, 2012, and the IEEE 802.1 lax/Dl .0, published November 2016. The embodiments are not limited to these.

Embodiments may facilitate wireless communications in accordance with multiple standards. Some embodiments may comprise low power wireless communications like Bluetooth®, cellular communications, and messaging systems. Furthermore, some wireless embodiments may incorporate a single antenna while other embodiments may employ multiple antennas or antenna elements.

While some of the specific embodiments described below will reference the embodiments with specific configurations, those of skill in the art will realize that embodiments of the present disclosure may advantageously be implemented with other configurations with similar issues or problems.

Turning now to FIG. 1, there is shown an embodiment of a wireless network in a collaborative area 1000 comprising a plurality of communications devices, including multiple fixed or mobile communications devices. The plurality of communications devices comprises a central server 1010, APs 1020, 1030, 1040, and 1050, and stations 1060, 1070, 1080, and 1090. The central server 1010 may be wired and wirelessly connected 1015 to each of the APs 1020, 1030, 1040, and 1050 and the stations 1060, 1070, 1080, and 1090 are each within wireless communications range of the APs 1020, 1030, 1040, and 1050.

The collaborative area 1000 may be an area in which a network operator decided to establish a set of collaborative APs (C-APs). The network operator may manually assign APs 1020, 1030, 1040, and 1050 to the set of C-APs or the central server 1010 may be configured to establish the set of C-APs based on default criteria or criteria set by the network operator. For instance, the central server 1010 may select APs 1020, 1030, 1040, and 1050 for inclusion in the set of C-APs based upon their proximity to one another, their proximity to a particular location, quality of service requirements for stations in or expected to be in the location proximate to the APs 1020, 1030, 1040, and 1050, their location within a mobile unit, or other criteria.

The collaborative area 1000 may be a part of a network for a dense set of wireless client devices such as the stations 1060, 1070, 1080, and 1090. The network may include multiple collaborative areas such as the collaborative area 1000 that are form adjacent basic service sets (BSSs) operating on the same or different channels and, in some embodiments, at least partially overlapping basic service sets (OBSSs) that operate on the same or different channels.

The central server 1010 or a network operator may transmit to the APs 1020, 1030, 1040, and 1050 an indication of their assignment to the set of C-APs. In some embodiments, when assigning the APs 1020, 1030, 1040, and 1050 to the set of C-APs, the central server 1000 or a network operator may assign a color to the APs 1020, 1030, 1040, and 1050. The color may distinguish the basic service sets (BSSs) created by each of the APs 1020, 1030, 1040, and 1050 in the set of C-APs from APs in OBSSs and each of the stations 1060, 1070, 1080, and 1090 that associate with the set of C- APs may adopt the color from the C-APs. In some embodiments, the color may be included in a SIG field of the physical layer (PHY) preamble of transmissions from C-APs and stations associated with the C-APs to reduce decoding of packets necessary to distinguish packets originating within a BSS of the C-APs and a packet originating from an OBSS. In other embodiments, each BSS within the set of C-APs may include a different color and, in another embodiment, the color indication may be included in a MAC frame in addition to or as an alternative to inclusion in the PHY preamble.

In many embodiments, the APs 1020, 1030, 1040, and 1050 transmit beacons to the stations 1060, 1070, 1080, and 1090 or the stations 1060, 1070, 1080, and 1090 transmit probe requests to and receive probe responses from the APs 1020, 1030, 1040, and 1050 to begin a process of associating each of the stations 1060, 1070, 1080, and 1090 with the set of C-APs. In some embodiments, the stations 1060, 1070, 1080, and 1090 may transmit association requests to the APs to establish associations and receive association identifiers (AIDs).

Each station 1060, 1070, 1080, and 1090 may associate with each AP 1020, 1030, 1040, and

1050 in the set of C-APs. Each station 1020, 1030, 1040, and 1050 may associate with one of the C- APs as a primary AP and the remainder of the C-APs that can be sensed at the station as secondary APs. Each station 1060, 1070, 1080, and 1090 may determine the AP in the C-AP set with which to associate as a primary AP based on default settings, default criteria, settings by a network operator, or an indication from one or more of the C-APs. In several embodiments, each station 1060, 1070, 1080, and 1090 may select a primary AP based on the signal-to-noise ratio (SNR) associated with communications with, or transmissions from, the C-APs. In further embodiments, the stations 1060, 1070, 1080, and 1090 may select a primary AP from the C-APs based on one or more factors such as a received signal strength indicator (RSSI), a received channel power indicator (RCPI), a signal to interference plus noise ratio (SNIR), a signal to interference ratio (SIR), and/or other channel quality indicators.

In the present embodiment, the station 1060 may associate with AP 1020 as a primary AP based on an SNR determined from the beacon or probe response transmissions from the AP 1020. The station 1060 may also be referred to as a primary station with respect to AP 1020 and a secondary station with respect to other C-APs including the APs 1030, 1040, and 1050. Similarly, stations 1070, 1080, and 1090 may associate with the APs 1030, 1040, and 1050, respectively, as primary APs.

After two or more stations 1060, 1070, 1080, and 1090 associate with the set of C-APs, the C-APs may initiate collaborative beamforming (CBF). CBF may be initiated by one of the APs 1020, 1030, 1040, and 1050. The AP that initiates the CBF may do so based on a default setting, a default process for determining which AP of the C-APs will initiate CBF, by an indication from the central server 1010, by a setting by a network operator, or by another process. The AP 1020 may, for instance, initiate CBF based on having the lowest number least significant bits (LSBs) in the medium access control (MAC) address of the set of C-APs.

The AP 1020 may initiate CBF by transmitting a CBF announcement. The CBF announcement may be a MAC layer CBF announcement frame prepended by a PHY preamble. In some embodiments, the CBF announcement frame may be a CBF null data packet (NDP) announcement frame. The CBF announcement may be broadcast to all the stations 1060, 1070, 1080, and 1090 associated with the set of C-APs.

The CBF announcement may comprise one or more indications or field values to inform stations 1060, 1070, 1080, and 1090 about the CBF such as an indication of the order of upcoming channel sounding by each of the APs 1020, 1030, 1040, and 1050 in the set of C-APs; an identifier (ID) for each of the APs 1020, 1030, 1040, and 1050; an order for transmission of beamforming (BF) feedback reports from the stations 1060, 1070, 1080, and 1090; and an indication of primary stations associated with each of the APs 1020, 1030, 1040, and 1050. The CBF announcement may also include details about the BF feedback reports to transmit in response to the channel sounding. In several embodiments, the CBF announcement frame may include a mapping of stations 1060, 1070, 1080, and 1090 to subchannels or resource units of the channel for transmitting BF feedback reports to the APs 1020, 1030, 1040, and 1050.

After transmitting the CBF announcement, the AP 1020 may transmit a channel sounding packet. In many embodiments, the channel sounding packet may comprise a physical layer PHY null data packet (NDP). For instance, the channel sounding packet may include a very high throughput (VHT) NDP or a high efficiency (HE) NDP. In some embodiments, the PHY logic circuitry of AP 1020 may automatically transmit the channel sounding packet an interframe space (IFS), such as a short interframe space (SIFS), after transmission of the CBF announcement. In other embodiments, the MAC logic circuitry may control the timing of transmission of the channel sounding packet.

If the CBF announcement includes a mapping for subchannels, a group of the primary stations including some or all the primary stations for AP 1020, such as station 1060, may respond to the channel sounding packet simultaneously on different subchannels in accordance with the mapping. In many embodiments, the primary stations for AP 1020 such as station 1060 have a default setting to or receive an indication in the CBF announcement or a BF report poll to transmit full rank, channel state information in the BF feedback report to the AP 1020. In several embodiments, secondary stations for AP 1020, such as stations 1070, 1080, and 1090, have a default setting to or receive an indication in the CBF announcement or a BF report poll to transmit rank one, channel state information in the BF feedback report to the AP 1020. The rank one, channel state information may include channel state information calculated by the station based on one BF eigenvector such as the eigenvector received with the largest eigenvalue.

The AP 1020 may transmit a BF report poll an IFS after receipt of the BF feedback report from station 1020 to the next station in the order indicated in the CBF announcement. The next station 1070 may be a secondary station. In some embodiments, the AP 1020 may transmit a BF report poll addressed to the next station 1070 or may broadcast the BF report poll to all secondary stations. In the former embodiments, each of the stations 1070, 1080, and 1090 will respond an IFS after receipt of their respective BF report polls. In the latter embodiments, the stations 1070, 1080, and 1090 may transmit BF feedback reports to the AP 1020 simultaneously on different subchannels of the channel. In other embodiments, the stations 1070, 1080, and 1090 may determine access windows for response based on the order of station responses indicated in the CBF announcement.

Thereafter, each subsequent AP 1030, 1040, and 1050 in the set of C-APs may perform the CBF similarly to obtain channel information from each of their respective primary and secondary stations in a time-division multiple access (TDMA) procedure. The TDMA procedure may assign a time slot or access window to each of the APs 1020, 1030, 1040, and 1050 to obtain BF feedback reports from each of the primary and secondary stations 1060, 1070, 1080, and 1090.

After receipt of one or more of the BF feedback reports from the primary and secondary stations 1060, 1070, 1080, and 1090; APs 1020, 1030, 1040, and 1050 may transmit processed and/or unprocessed channel information from the BF feedback reports to the central server 1010 via a wired or wireless connection 1015 between the APs 1020, 1030, 1040, and 1050 and the central server 1010.

After the C-APs transmit the channel information from the BF feedback reports to the central server 1010, the CBF may be complete and the central server 1010 may process the channel information to determine one or more schedules for simultaneous transmissions 1025, 1035, 1045, and 1055 by two or more of the APs 1020, 1030, 1040, and 1050 of the set of C-APs, respectively, to two or more of their primary stations 1060, 1070, 1080, and 1090, respectively. The central server 1010 may process the channel information to estimate channel interference at the stations and the C- APs. Based on channel interference, the central server 1010 may determine the one or more schedules of simultaneous transmissions that can occur on the same channel without exceeding a threshold of channel interference at the stations and C-APs receiving the transmissions. FIG. 2A illustrates an embodiment of a timing diagram 2100 for collaborative beamforming (CBF) by one of the access points (APi) in a set of collaborative APs (C-APs) such as the APs illustrated in FIG. 1. For example, the timing diagram 2100 may represent an access window for AP 1030. The AP 1030 may be the second AP in the order indicated to perform CBF in the CBF NDP announcement frame transmitted by the AP 1020. The AP 1030 may transmit a CBF NDP announcement frame 2110 that indicates the same order of APs and stations as indicated in the CBF NDP announcement frame transmitted by the AP 1020. In other embodiments, once the AP 1020 initiates CBF, subsequent CBF announcements do not have to re-transmit the order.

The AP 1030 may transmit channel sounding including a very high throughput (VHT) null data packet (NDP) 2120 a short interframe space (SIFS) after transmitting the CBF NDP announcement frame 2110. The AP 1030 may expect the first primary station to respond to the channel sounding, such as the station 1070 (Primary STAl), a SIFS after completion of the channel sounding. If the Primary STAl has not completed calculations of the channel based on the channel sounding, the Primary STAl may not respond. In some embodiments, the AP 1030 may wait a timeout period, determine that the Primary STAl failed to respond during the timeout period, and respond by transmitting, immediately thereafter, a beamforming (BF) report poll to the Primary STAl . If a station fails to respond a SIFS after receipt of the sounding packet and/or after a transmission of BF report poll, the AP 1030 may determine that the Primary STAl is unable to participate in the CBF. The AP 1030 may also transmit BF report polls to subsequent station(s) such as the station 1070 (Primary STAs) prior to transmitting a BF report poll to the Primary STAl .

If the Primary STAl responds to the VHT NDP 2120 with a BF feedback report 2125 a SIFS after transmission of the VHT NDP 2120, the AP 1030 may proceed to transmit the primary BF report polls 2130 sequentially to each of the remaining primary stations. In the present embodiment, the AP 1030 may transmit a primary BF report poll 2130 to a second primary station (Primary STAs) for AP 1030 and may receive a BF feedback report 2135 from the second primary station (Primary STAs). If additional Primary STAs remain to be polled, the AP 1030 may transmit a primary BF report poll to the next primary station and receive a BF feedback report a SIFS thereafter.

After receiving BF feedback reports from each of the primary stations, the AP 1030 may sequentially transmit secondary BF report polls 2140 to each of the remaining secondary stations 1060, 1080, and 1090. A SIFS after transmitting each secondary BF report poll, each secondary station may respond with a BF feedback report 2145. In some embodiments, the primary and secondary BF report polls comprise the same content with the exception that the recipient address is the address of the intended recipient station. In other embodiments, the primary BF report poll may indicate, for instance, the requested feedback segments for the BF feedback report for the primary stations and the secondary BF report poll may indicate, for instance, different requested feedback segments for the BF feedback report for the secondary stations.

Referring now to FIG. 2B, there is illustrated an alternative embodiment of a timing diagram 2200 for CBF by each of the access points (APi) such as the APs depicted in FIG. 1. The APi may transmit a CBF NDP announcement frame 2210. The CBF NDP announcement frame 2210 may include instructions for a group of stations associated with a set of C-APs to transmit BF feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA). In some embodiments, the CBF NDP announcement frame 2210 may include one or more fields to assign subchannels to the group of stations to facilitate simultaneous transmission of the BF feedback reports from the group of stations on different subchannels of a channel. In several embodiments, the CBF NDP announcement frame 2210 may assign subchannels to the group of stations based on the order of response by the stations indicated in the CBF NDP announcement frame 2210.

The CBF NDP announcement frame 2210 may assign, e.g., two subchannels to the group of stations. In some embodiments, the CBF NDP announcement frame 2210 indicates the number or structure of the subchannels and each station determines the subchannel to which the station is assigned based on the order of response for the stations indicated in the CBF NDP announcement frame 2210. In other embodiments, the CBF NDP announcement frame 2210 may include an indication of a subchannel assigned to each station.

The CBF NDP announcement frame 2210 may assign the Primary STA1, Primary STA3, and Secondary STA1 to a first subchannel and may assign the Primary STA2, Primary STA4, and Secondary STA2 to the second subchannel. A SIFS after transmitting the channel sounding packet, VHT NDP 2220, two primary stations, the Primary STA1 and Primary STA2, may transmit BF feedback reports 2225 and 2227 to the APi via the two subchannels of the channel.

A SIFS after receiving the BF feedback reports from the Primary STA1 and Primary STA2, the APi may transmit a primary BF report poll addressed to the Primary STA3 and Primary STA4 or broadcast to all the stations. A SIFS after transmitting the primary BF report poll 2230, the Primary STA3 and Primary STA4 may transmit BF feedback reports 2235 and 2237 via the two subchannels.

The APi may transmit a secondary BF report poll 2240 a SIFS after receipt of the BF feedback reports from the last group of the primary stations, Primary STA3 and Primary STA4 and may receive the BF feedback reports 2245 and 2247 from the secondary stations, Secondary STA1 and Secondary STA2, respectively, a SIFS thereafter.

FIGs. 2C-2E illustrate embodiments of channels and subchannels (or resource units) that can facilitate multiple transmissions simultaneously on different subchannels of a channel such as the transmission of multiple BF feedback reports from different stations associated with a set of C-APs. In some embodiments, after completion of the CBF, a central server, such as the central server 1010 in FIG. 1, may also schedule multiple simultaneous transmissions on multiple overlapping subchannels of the channel between two or more APs in the set of C-APs.

FIG. 2C illustrates an embodiment of transmissions 2400 between four stations and an AP on four different subchannels (or resource units) of a channel via OFDMA. Grouping subcarriers into groups of resource units is referred to as subchannelization. Subchannelization defines subchannels that can be allocated to stations depending on their channel conditions and service requirements. An OFDMA system may also allocate different transmit powers to different subchannels.

In the present embodiment, the OFDMA STA1, OFDMA STA2, OFDMA ST A3, and OFDMA STA4 may represent transmissions by four different stations (STA1, STA2, STA3, and STA4) on four different subchannels of the channel. As a comparison, FIG. 2D illustrates an embodiment of an OFDM transmission 2410 for the same channel as FIG. 2C. The OFDM transmission 2410 may use the entire channel bandwidth for one station, STA.

FIG. 2E illustrates an embodiment of a 20 Megahertz (MHz) bandwidth 2420 on a channel that illustrates different resource unit (RU) configurations 2430, 2440, 2450, and 2460. In OFDMA, for instance, an OFDM symbol is constructed of subcarriers, the number of which is a function of the physical layer convergence procedure (PLCP) protocol data unit (PPDU) (also referred to as the PHY frame) bandwidth. There are several subcarrier types: 1) Data subcarriers which are used for data transmission; 2) Pilot subcarriers which are utilized for phase information and parameter tracking; and 3) unused subcarriers which are not used for data/pilot transmission. The unused subcarriers are the direct current (DC) subcarrier(s), the Guard band subcarriers at the band edges, and the Null subcarriers.

The RU configuration 2430 illustrates an embodiment of nine RUs that each include 26 subcarriers for data transmission including the two sets of 13 subcarriers on either side of the DC. The RU configuration 2440 illustrates the same bandwidth divided into 5 RUs including four RUs with 52 subcarriers and one RU with 26 subcarriers about the DC for data transmission. The RU configuration 2450 illustrates the same bandwidth divided into 3 RUs including two RUs with 106 subcarriers and one RU with 26 subcarriers about the DC for data transmission. Furthermore, the RU configuration 2460 illustrates the same bandwidth divided into 2 RUs including two RUs with 242 subcarriers about the DC for data transmission. Embodiments may be capable of additional or alternative bandwidths such as such as 40 MHz, 80 MHz, 160 MHz and 80+80MHz.

FIG. 2F depicts an embodiment of a collaborative beamforming (CBF) null data packet (NDP) announcement frame 2500 such as the CBF NDP announcement frames 2110 and 2210 illustrated in FIGs. 2A and 2B. The CBF NDP announcement frame 2500 is one embodiment of a frame that can transmit information to initiate the CBF. The choice of fields for communicating information may be application specific. In other embodiments, for example, the frame 2500 may have more or less fields, different fields, and/or fields with different field lengths. In many embodiments, the CBF announcement may communicate to the stations associated with a set of collaborative APs (C-APs) a predetermined sequence or order of channel soundings by the C-APs, an order for stations to respond to channel soundings by the stations, and the identifiers (IDs) of the APs in the set of C-APs.

The CBF NDP announcement frame 2500 may comprise a MAC header 2505 with a frame control field 2510, a duration field 2520, a receive address (RA) field 2525, a transmit address (TA) field 2530, a sounding sequence field 2535, a feedback report type field 2540, and also a set of AP ID fields with primary station fields, an optional padding field 2580, and a frame check sequence (FCS) field 2590. The frame control field 2510 may comprise a protocol version field 2512, a type field 2514, a subtype field 2516, and other frame control bits 2518. The protocol version field 2512 may represent the revision of the corresponding standard that the frame represents. The type field 2514 may identify the type of frame 2514 as, e.g., a control frame. The subtype field 2516 may identify the subtype of the frame as, e.g., a particular type of control frame such as an NDP announcement frame. The other frame control bits 2518 may represent additional fields that may be present in the frame control field such as a more fragments field, a retry field, a power management field, a more data field, or the like.

The duration field 2520 may include a duration of a network allocation vector (NAV) reminder in microseconds. The RA field 2525 may include a broadcast address to broadcast to each station associated with the set of C-APs. The TA address field 2530 may include an address such as a MAC address of the AP that transmits the CBF NDP announcement frame 2500 (the beamformer). The sounding sequence field 2535 may include a value selected by the beamformer to identify the CBF NDP Announcement frame 2500. In many embodiments, the value in the sounding sequence field 2535 may differ between the APs that transmit the CBF NDP Announcement frame 2500.

The feedback report type field 2540 may include values indicative of the requested feedback segments of the BF feedback report. In some embodiments, the feedback report type field 2540 may include values indicative of a full rank feedback for primary stations and a rank one feedback for secondary stations. In further embodiments, the feedback report type field 2540 may include a structure such as the RU configuration for transmitting BF feedback reports to the AP via OFDMA.

The first AP is AP ID1 2545 and the station fields STA info 1-1 2550 through STA info 1- Nl 2555 represent the ID and the primary stations associated with the AP ID1 2545. The last AP in the list is the AP IDk 2560 and stations STA info kl-1 2565 through STA info 1-Nk 2570 represent the ID and primary stations for the AP IDk 2560. In some embodiments, the AP ID fields may include an identifier such as a basic service set identifier (BSSID), a MAC address, a partial or compressed ID, or another ID.

The padding 2580 may be included to adjust the length of the frame and the Frame Check Sequence (FCS) field 2590 may include a 32-bit cyclic redundancy sequence used to detect errors in the received frame.

FIG. 2G illustrates an embodiment of a station information field 2600 in a CBF announcement frame such as the CBF NDP announcement frame 2500 illustrated in FIG. 2F. The station information fields (STA info 1-1 2550 through STA info 1-Nl 2555 ... STA info kl-1 2565 through STA info 1- Nk 2570) may include, for example, an association identifier (AID) field 2610, a partial bandwidth field 2620, and other bits 2630. The AID field 2610 may include the AID or a partial AID for the station. The partial bandwidth field 2620 may identify a partial bandwidth for which the AP is requesting the BF feedback report. Furthermore, the other bits 2630 may include, e.g., a codebook size.

FIG. 2H illustrates an embodiment of a partial bandwidth field 2650 in a station information field such as the station information field 2600 illustrated in FIG. 2G. The partial bandwidth field 2650 may include an RU start index field 2652 and an RU end index 2654. The RU Start Index subfield 2652 may indicate the first 26-tone RU for which the CBF beamformer is requesting feedback. The RU End Index subfield 2654 may indicate the last 26-tone RU for such feedback.

FIG. 21 depicts an embodiment of a channel sounding packet, VHT NDP 2700, such as the

VHT NDPs 2120 and 2220 illustrated in FIGs. 2A and 2B. The VHT NDP 2700 may include a legacy short training field (L-STF 2710) that is 8 microseconds; a legacy long training field (L-LTF 2720) that is 8 microseconds in length; and a legacy signal field (L-SIG 2730) that is 4 microseconds in length. The VHT NDP 2700 may also include a VHT signal-A field (VHT SIG-A 2740) that is 8 microseconds in length and may include bits to indicate a color representing the set of C-APs.

The VHT NDP 2700 may also include a VHT STF field 2750 that is 4 microseconds in length, a VHT LTF field 2760 that is 4 microseconds per symbol in length, and a VHT SIG-B field 2770 that is 4 microseconds in length. In other embodiments, the number of fields and the lengths may vary.

FIG. 2J illustrates an embodiment of a BF report poll frame 2800 such as the primary and secondary BF report polls 2130, 2140, 2230, and 2240 illustrated in FIGs. 2A and 2B. The BF report poll frame 2800 may comprise a frame control field 2810, a duration field 2820, a receive address (RA) field 2825, a transmit address (TA) field 2830, a feedback segment retransmission bitmap field 2835, and a frame check sequence (FCS) field 2890. The frame control field 2810 may comprise a protocol version field 2812, a type field 2814, a subtype field 2816, and other frame control bits 2818. The value of the protocol version field 2812 may represent the revision of the corresponding standard for the frame. The type field 2814 may identify the type of frame as, e.g., a control frame. The subtype field 2816 may identify the subtype of the frame as, e.g., a particular type of control frame such as a BF report poll frame. The other frame control bits 2818 may represent additional fields that may be present in the frame control field such as a more fragments field, a retry field, a power management field, a more data field, or the like.

The duration field 2820 may include a duration of a network allocation vector (NAV) reminder in microseconds. The RA field 2825 may include an address for a station associated with the set of C-APs or a broadcast address. Furthermore, the TA address field 2830 may include an address such as a MAC address of the AP that transmits the BF report poll 2800.

The Feedback Segment Retransmission Bitmap subfield 2835 may indicate the requested feedback segments of a Compressed Beamforming feedback report. Furthermore, the Frame Check Sequence (FCS) field 2890 may include a 32-bit cyclic redundancy sequence used to detect errors in the frame.

FIG. 2K illustrates an embodiment of a compressed BF report such as BF feedback reports illustrated in FIGs. 2A and 2B. The BF feedback report may comprise a MAC layer action frame called a compressed BF report frame 2900. In other embodiments, the BF feedback report may comprise a different type of frame such as a data frame or a physical layer (PHY) frame. The compressed BF report frame 2900 comprises a frame control field 2910, a duration field 2920, a receive address (RA) field 2925, a transmit address (TA) field 2930, VHT action frame fields 2940, and a frame check sequence (FCS) field 2945.

The frame control field 2910 may comprise a protocol version field 2912, a type field 2914, a subtype field 2916, and other frame control bits 2918. The type field 2914 may identify the type of frame as, e.g. an action frame. The subtype field 2916 may identify the subtype of the frame as, e.g., a VHT action frame. The duration field 2920 may include a duration of a network allocation vector (NAV) reminder. The RA field 2925 may include an AP address to identify the destination AP of the set of C-APs. Furthermore, the TA address field 2930 may include an address such as a MAC address of the station that transmits the compressed BF report frame 2900.

The VHT action frame fields 2940 may comprise a category field 2932, a VHT action field 2933, VHT MIMO control field 2934, a VHT compressed BF report field 2935, and a multi-user (MU) Exclusive BF report 2936. In several embodiments, some of these fields are optional and are only included if applicable to the deployment. The VHT Action field 2933, in the octet immediately after the Category field, differentiates the VHT Action frame formats. The category field 2932 may be set to a value for VHT. The VHT action field 2933 may be set to the value for VHT Compressed Beamforming. The VHT MIMO control field 2934 may include values to describe the feedback.

The presence and contents of the VHT Compressed Beamforming Report field and the MU Exclusive Beamforming Report field are dependent on the values of the Feedback Type, Remaining Feedback Segments, and First Feedback Segment subfields of the VHT MIMO control field 2934. Furthermore, the VHT compressed BF report field 2935 may indicate compressed BF feedback matrices.

FIG. 2L illustrates an embodiment of a very high throughput multiple input, multiple output (VHT MIMO) control field such as VHT MIMO control field 2934 illustrated in FIG. 2K. The VHT MIMO control field 2950 may comprise one or more fields such as an Nc index field 2952, an Nr index field 2954, a channel width field 2956, a grouping field 2958, a codebook information field 2960, a feedback type field 2962, a remaining feedback segments field 2964, a first feedback segment field 2966, a reserved field 2968, and a sounding token field 2970. The Nc index field 2952 may include a value that indicates the number of columns in the compressed feedback matrix minus 1 and the Nr index field 2954 may include a value that indicates the number of rows in the compressed feedback matrix minus 1. The channel width field 2956 may include a value that identifies the bandwidth of the channel for which the measurement is made. For instance, the channel width field 2956 value may be set to zero to indicate 20 MHz, one to indicate 40 MHz, two to indicate 80 MHz, and 3 to indicate 160 MHz or 80+80 MHz.

The grouping field 2958 may include a value that indicates a subcarrier grouping used for the compressed BF feedback matrix. The codebook information field 2960 may include a value that indicates the size of codebook entries. The feedback type field 2962 may include a value that indicates whether the feedback is single user (SU) or multi-user (MU). The remaining feedback segments 2964 may include a value to indicate the number of remaining feedback segments for the associated VHT compressed BF frame. The first feedback segment field 2966 may include a value to indicate if this is the first segment of a report or the only segment of the report and a value to indicate if neither the Compressed Beamforming Report field nor the MU Exclusive Beamforming Report field are present in the frame. The reserved field 2968 may be bits reserved for another function. Furthermore, the sounding dialog token 2970 may include the sounding sequence from the CBF NDP Announcement frame soliciting feedback such as the value in the sounding sequence field 2535 in FIG. 2F.

FIG. 3 depicts an embodiment of a system 3000 to beamform a set of collaborative APs (C-

APs) as well as to generate, transmit, receive, decode, and interpret simultaneous transmissions between multiple APs and multiple primary stations. The system 3000 comprises a plurality of communication devices 3010, 3030, 3050, 3055, and 3060 connected via the network 3005. The central server 3060 may comprise a station such as a computer, laptop, netbook, smart phone, or other processing device that can be wired to or wirelessly connected to the APs 3010 and 3055. A network operator or the central server 3060 may assign the APs 3010 and 3055 to a set of C-APs and the APs 3010 and 3055 may each establish a basic service set (BSS).

The stations 3030 and 3050 may comprise a communications device such as a computer, laptop, netbook, smart phone, or other wireless-capable devices. Furthermore, the stations 3030 and 3050 can associate with multiple APs. For instance, the station 3030 may associate with AP 3010 as a primary AP and with AP 3055 as a secondary AP. The station 3050 may associate with AP 3055 as a primary AP and with AP 3010 as a secondary AP. Thus, the station 3030 may be considered a primary station with respect to the AP 3010 and a secondary station with respect to the AP 3055. Furthermore, the station 3050 may be considered a primary station with respect to the AP 3055 and a secondary station with respect to the AP 3010. The CBF logic circuitry 3014 may be part of the MAC logic circuitry 3018 in AP 3010 and may initiate CBF by transmitting a CBF announcement such as the MAC CBF NDP announcement frame 2500 illustrated in FIG. 2F. The CBF logic circuitry 3014 may broadcast the CBF announcement to all stations 3030 and 3050 associated with the C-APs to inform the stations 3030 and 3050 that CBF is starting. The CBF announcement may provide the stations 3030 and 3050 with the identifiers (IDs) of all the APs 3010 and 3055 in the set of C-APs, inform the stations 3030 and 3050 of the order of channel sounding by the APs 3010 and 3055, and inform the stations 3030 and 3050 of the order in which the stations are expected to respond to the channel soundings with BF feedback reports.

After transmitting the CBF announcement, the CBF logic circuitry 3014 may perform channel sounding by transmitting, e.g., the VHT NDP 2700 illustrated in FIG. 21. Transmission of the CBF announcement may initiate a physical layer (PHY) procedure implemented by the PHY logic circuitry 3029 and PHY logic circuitry of primary stations such as PHY logic circuitry 3039 of station 3030 to perform the remainder of the BF process. In such embodiments, the PHY logic circuitry 3029 may transmit PHY BF feedback report polls, process channel information received from stations, and transmit channel information from the stations to the MAC layer after completion of the CBF process. In other embodiments, the CBF logic circuitry 3014 may initiate each step of the CBF process for AP 3010 and may transmit MAC layer BF report polls.

The CBF logic circuitry 3034 of MAC logic circuitry 3038 of the first station 3030 may respond to channel sounding an interframe space after receipt of the channel sounding packet with a BF feedback report such as the compressed BF report frame 2900 illustrated in FIG. 2K. The CBF logic circuitry 3014 may then transmit a BF report poll to each of the remaining stations such as station 3050 to trigger transmission of BF feedback reports from the remaining stations.

Once the AP 3010 receives BF feedback reports from all the stations 3030 and 3050, the AP 3010 may transmit channel information from the BF feedback reports to the CBF logic circuitry 3066 of the central server 3060 via the AP interface 3070 and then the next AP 3055 may perform CBF. The AP interface 3070 may comprise a wired and/or wireless communications interface to facilitate communications between the APs 3010 and 3055 and CBF logic circuitry 3066.

The CBF logic circuitry 3066 may comprise one or more processors and memory or may interface with the processor(s) 3062 and code in memory 3064 of the central server 3060. The CBF logic circuitry 3066 may process the channel information from the stations 3030 and 3050 for channel interference estimation and channel directivity in relation to each AP 3010 and 3055 in the set of C- APs. The CBF logic circuitry 3066 may estimate a magnitude of interference caused at each station 3030 and 3050 and at each access point 3010 and 3055. The CBF logic circuitry 3066 may also base one or more channel interference calculations on adjusted transmission power levels for APs and stations capable of operating in a spatial reuse mode, which may reduce transmission power by adjusting power amplification by a power amplifier in the front end of a transmitter.

After estimating the channel interference and channel directivity, the scheduling circuitry 3068 may process the interference information and channel directivity associated with each of the simultaneous transmissions in a schedule to determine schedules for transmissions between each of the APs 3010 and 3055 and their primary stations 3030 and 3050, respectively. The central server 3060 may transmit the schedules via the AP interface 3070 to the APs 3010 and 3055. In some embodiments, the schedules may include transmission power adjustments.

The AP 3010, the station 3030 and the central server 3060 comprise processor(s) 3001, 3002, and 3062, and memory 3011, 3031, and 3064, respectively. The processor(s) 3001, 3002, and 3062 may comprise any data processing device such as a microprocessor, a microcontroller, a state machine, and/or the like, and may execute instructions or code in the memory 3011, 3031, and 3064. The memory 3011, 3031, and 3064 may comprise a storage medium such as Dynamic Random Access Memory (DRAM), read only memory (ROM), buffers, registers, cache, flash memory, hard disk drives, solid-state drives, or the like. The memory 3011, 3031, and 3064 may store 3012 and 3032 the frames, frame structures, frame headers, etc., and may also comprise code to execute CBF logic.

The MAC logic circuitry 3018 and 3038 may comprise one or more circuits to implement

MAC layer functionality and management service interfaces through which MAC layer management functions may be invoked. The MAC logic circuitry 3018 and 3038 may comprise one or more processors to execute MAC layer code stored in the memory 3011 and 3031, respectively. In other embodiments, the MAC logic circuitry 3018 and 3038 may comprise interface circuitry to execute code on the one or more processors 3001 and 3002, respectively.

The MAC logic circuitry 3018 and 3038 may communicate with the physical layer (PHY) logic circuitry 3029 and 3039, respectively, to transmit a PHY frame such as a channel sounding packet or may provide a MAC frame such as the CBF DP announcement frame to the PHY logic circuitry 3029 and 3039 to transmit to the station 3030 and the AP 3010, respectively. The MAC logic circuitry 3018 and 3038 may generate frames such as management, data, and control frames.

The PHY logic circuitry 3029 and 3039 may prepare the MAC frame for transmission by, e.g., determining a preamble to prepend to a MAC frame to create a PHY frame. The preamble may include one or more short training field (STF) values, long training field (LTF) values, and signal (SIG) field values. The PHY layer device such as the transmitters of the transceivers (RX/TX) 3020 and 3040 may then process the PHY frame to transmit.

After processing the PHY frame, a radio 3025 and 3045 comprising an RF transmitter and an RF receiver, may impress digital data onto subcarriers of RF frequencies for transmission by electromagnetic radiation via elements of an antenna array or antennas 3024 and 3044, respectively. The RF receiver receives electromagnetic energy, extracts the digital data, and decodes the frame.

FIG. 4 depicts an embodiment of an apparatus to generate, transmit, receive, and interpret or decode PHY frames and MAC frames. The apparatus comprises a transceiver 400 coupled with MAC logic circuitry 401 and PHY logic circuitry 402. The MAC logic circuitry 401 may determine a frame such as a CBF announcement frame and the PHY logic circuitry 402 may determine a physical layer convergence procedure (PLCP) protocol data unit (PPDU) by prepending the frame or multiple frames, also called MAC protocol data units (MPDUs), with a preamble to transmit.

The transceiver 400 comprises a receiver 404 and a transmitter 406. Embodiments have many different combinations of modules to process data because the configurations are deployment specific. FIG. 4 illustrates some of the modules that are common to many embodiments.

The transmitter 406 may comprise one or more of an encoder 408, a stream deparser 464, a frequency segment parser 407, an interleaver 409, a modulator 410, a frequency segment deparser 460, an OFDM 412, an IFFT 415, a GI 445, and a transmitter front end 440. The encoder 408 of transmitter 406 receives and encodes a data stream destined for transmission from the MAC logic circuitry 402 with, e.g., a binary convolutional coding (BCC), a low-density parity check coding (LDPC), and/or the like. After coding, scrambling, puncturing and post-FEC padding, a stream parser 464 may optionally divide the data bit streams at the output of the FEC encoder into groups of bits. The frequency segment parser 407 may receive data stream from encoder 408 or streams from the stream parser 464 and optionally parse each data stream into two or more frequency segments to build a contiguous or non-contiguous bandwidth based upon smaller bandwidth frequency segments. The interleaver 409 may interleave rows and columns of bits to prevent long sequences of adjacent noisy bits from entering a BCC decoder of a receiver.

The modulator 410 may receive the data stream from interleaver 409 and may impress the received data blocks onto a sinusoid of a selected frequency for each stream via, e.g., mapping the data blocks into a corresponding set of discrete amplitudes of the sinusoid, or a set of discrete phases of the sinusoid, or a set of discrete frequency shifts relative to the frequency of the sinusoid. In some embodiments, the output of modulator 410 may optionally be fed into the frequency segment deparser

460 to combine frequency segments in a single, contiguous frequency bandwidth of, e.g., 160 MHz.

Other embodiments may continue to process the frequency segments as separate data streams for, e.g. a non-contiguous 80+80 MHz bandwidth transmission.

After the modulator 410, the data stream(s) are fed to an OFDM module 412. The OFDM module 412 may comprise a space-time block coding (STBC) module 411, and a digital beamforming

(DBF) module 414. The STBC module 411 may receive constellation points from the modulator 410 corresponding to one or more spatial streams and may spread the spatial streams to a greater number of space-time streams. Further embodiments may omit the STBC.

The OFDM module 412 impresses or maps the modulated data formed as OFDM symbols onto a plurality of orthogonal subcarriers so the OFDM symbols are encoded with the subcarriers or tones. The OFDM symbols may be fed to the DBF module 414. Generally, digital beam forming uses digital signal processing algorithms that operate on the signals received by, and transmitted from, an array of antenna elements. Transmit BF processes the channel state to compute a steering matrix that is applied to the transmitted signal to optimize reception at one or more receivers. This is achieved by combining elements in a phased antenna array in such a way that signals at particular angles experience constructive interference while others experience destructive interference.

The Inverse Fast Fourier Transform (IFFT) module 415 may perform an inverse discrete

Fourier transform (IDFT) on the OFDM symbols to map on the subcarriers. The guard interval (GI) module 445 may insert guard intervals by prepending to the symbol a circular extension of itself. The

GI module 445 may also comprise windowing to optionally smooth the edges of each symbol to increase spectral decay.

The output of the GI module 445 may enter the transmitter front end 440. The transmitter front end 440 may comprise a radio 442 with a power amplifier (PA) 444 to amplify the signal and prepare the signal for transmission via the antenna array 418. In many embodiments, entrance into a spatial reuse mode by a communications device such as a station or AP may reduce the amplification by the PA 444 to reduce channel interference caused by transmissions.

The transceiver 400 may also comprise duplexers 416 connected to antenna array 418. The antenna array 418 radiates the information bearing signals into a time-varying, spatial distribution of electromagnetic energy that can be received by an antenna of a receiver. In several embodiments, the receiver 404 and the transmitter 406 may each comprise its own antenna(s) or antenna array (s). The transceiver 400 may comprise a receiver 404 for receiving, demodulating, and decoding information bearing communication signals. The receiver 404 may comprise a receiver front-end 450 to detect the signal, detect the start of the packet, remove the carrier frequency, and amplify the subcarriers via a radio 452 with a low noise amplifier (LNA) 454. The receiver 404 may comprise a GI module 455 and a fast Fourier transform (FFT) module 419. The GI module 455 may remove the guard intervals and the windowing and the FFT module 419 may transform the communication signals from the time domain to the frequency domain.

The receiver 404 may also comprise an OFDM module 422, a frequency segment parser 462, a demodulator 424, a deinterleaver 425, a frequency segment deparser 427, a stream deparser 466, and a decoder 426. An equalizer may output the weighted data signals for the OFDM packet to the OFDM module 422. The OFDM 422 extracts signal information as OFDM symbols from the plurality of subcarriers onto which information-bearing communication signals are modulated.

The OFDM module 422 may comprise a DBF module 420, and an STBC module 421. The received signals are fed from the equalizer to the DBF module 420. The DBF module 420 may comprise algorithms to process the received signals as a directional transmission directed toward to the receiver 404. Furthermore, the STBC module 421 may transform the data streams from the space- time streams to spatial streams.

The output of the STBC module 421 may enter a frequency segment parser 462 if the communication signal is received as a single, contiguous bandwidth signal to parse the signal into, e.g., two or more frequency segments for demodulation and deinterleaving.

The demodulator 424 demodulates the spatial streams. Demodulation is the process of extracting data from the spatial streams to produce demodulated spatial streams. The deinterleaver 425 may deinterleave the sequence of bits of information. The frequency segment deparser 427 may optionally deparse frequency segments as received, if received as separate frequency segment signals, or may deparse the frequency segments determined by the frequency segment parser 462. The decoder 426 decodes the data from the demodulator 424 and transmits the decoded information, the MPDU, to the MAC sublayer logic 402.

The MAC logic circuitry 401 may parse the MPDU based upon a format defined in the communications device for a frame to determine the particular type of frame by determining the type value and the subtype value. The MAC logic circuitry 401 may then interpret the remainder of MPDU.

While the description of FIG. 4 focuses on a single spatial stream system for simplicity, many embodiments are capable of multiple spatial stream transmissions and utilize parallel data processing paths for multiple spatial streams from the PHY logic circuitry 402 through to transmission. Further embodiments may include the use of multiple encoders to afford implementation flexibility.

FIG. 5 A-B depict embodiments of flowcharts for CBF of APs in a set of C-APs. In particular, FIG. 5A depicts an embodiment of a flowchart 500 for an AP to beamform as part of a set of C-APs such as the APs illustrated in FIG. 1. The flowchart 500 begins with MAC logic circuitry generating a CBF announcement frame (element 505). In some embodiments, the MAC logic circuitry may determine a control frame to initiate CBF. The control frame may include a feedback report type for primary and secondary stations and a predetermined sequence of channel sounding for each of the APs in the set of C-APs along with identifiers for each of the APs and information about each primary station associated with each of the APs. In some embodiments, the order of IDs for the APs indicates an order for channel sounding by each of the APs and the order of the information for primary stations may indicate the order in which each of the stations are expected to respond to the channel sounding with a channel information, or channel state information, in the form of a BF feedback report. The MAC logic circuitry may transmit the MAC frame to the PHY layer device to transmit.

After prepending a PHY preamble, the PHY device may transmit the CBF announcement frame to a group of stations associated with the set of C-APs (element 510). The PHY layer device may transmit a channel sounding packet an interframe space after transmitting the CBF announcement frame (element 515). The channel sounding packet may comprise a PHY frame including one or more short training fields, one or more long training fields, and one or more signal fields. The MAC logic circuitry may expect the first station in the order of stations to respond to the channel sounding packet with a BF feedback report, e.g., a short interframe space (SIFS) after receipt of the channel sounding packet.

A first group of one or more stations may transmit BF feedback reports simultaneously via different resource units or subchannels, in accordance with the order indicated in the CBF announcement frame (elements 520). In other embodiments, stations may transmit the BF feedback reports successively in accordance with the order indicated in the CBF announcement frame.

After receiving the one or more BF feedback reports from the stations a SIFS after transmission of the channel sounding packet, the MAC logic circuitry of the AP may determine if additional stations should respond to the channel sounding packet (element 525). If so, the MAC logic circuitry of the AP may generate and transmit a BF report poll to one or more of the remaining stations sequentially (element 530) to trigger transmissions to receive the BF feedback reports at element 520. The AP may process the channel information from each of the stations to complete digital BF for each of the primary stations for the AP. Furthermore, the AP may transmit channel information from both the primary and secondary stations for the AP to a central server (element 535). Transmitting the channel information to the central server may facilitate generation of schedules for simultaneous transmissions by two or more of the APs in the set of C-APs on the channel.

FIG. 5B depicts an embodiment of a flowchart 550 for a station to beamform a set of C-APs such as the stations illustrated in FIG. 1. The flowchart 550 begins with a PHY logic circuitry of the station receiving a PHY frame that includes the CBF announcement frame (element 555). The PHY logic circuitry may detect the communication by detection of an energy level at the receiver front end and, in response, begin processing the incoming OFDM packet. In some embodiments, after performing decoding the CBF announcement frame, the PHY logic circuitry may transmit the CBF announcement frame to MAC logic circuitry to deparse and interpret.

After receiving the CBF announcement frame, the PHY logic circuitry may receive a sounding packet (element 560) such as the VHT DP 2700 illustrated in FIG. 21. Based on the sounding packet, the PHY device of the station may calculate channel state information (element 565) including calculating a channel estimate. The extent of the calculations and the channel estimate may be based on whether the station is associated with the AP as a primary AP or a secondary AP. If the station is associated with the AP as a primary AP (i.e., a primary station), the CBF announcement frame may indicate that the station shall respond with, e.g., full rank, channel state information in a BF feedback report. On the other hand, if the station is associated with the AP as a secondary AP (i.e., a secondary station), the CBF announcement frame may indicate that the station shall respond with, e.g., rank one, channel state information in a BF feedback report.

Based on the order of response for stations indicated in the CBF announcement frame, the station may determine an access window during which to respond to the channel sounding packet (element 575). For instance, the station may calculate an access window based on knowledge of the timing for transmitting the channel sounding, the SIFS between transmissions of BF feedback reports, and timing for transmission of one or more BF report polls. In further embodiments, the station may determine that the access window will be a SIFS after receipt of a BF report poll addressed to the station. In further embodiments, the station may determine the access window by other methods.

At the access window, the MAC logic circuitry of the station may transmit a BF feedback report via a PHY device of the station (element 580). If there are more APs (element 585) in the set of C-APs to perform channel sounding, the station may begin again at element 555 with receipt of another CBF announcement frame from the next AP in the sequence of channel soundings indicated in the initial CBF announcement frame from the first AP to perform channel sounding.

FIG. 6 depicts an embodiment of a flowchart 600 of a central server to BF a set of C-APs such as the central servers 1010 and 3060 illustrated in FlGs. 1 and 3. The flowchart 600 may begin with determining a set of C-APs (element 605). The central server may receive a setting from a network operator indicating the APs to include in a set of C-APs. Or, the central server may determine a set of C-APs based on one or more of multiple different factors such as the location of APs being near a point of interest, locations of other sets of C-APs, quality of service considerations, and other potential factors.

Upon determining the set of C-APs, the central server may transmit an indication of the set of

C-APs such as basic service set identifiers (BSSIDs) and/or addresses for each of the APs in the set to other APs in the set (element 610). In some embodiments, the central server may broadcast a frame with the indications of APs in the set of C-APs to the APs. In other embodiments, a network operator may configure each of the APs with settings indicative of being part of the set of C-APs.

After establishing the set of C-APs, the set of C-APs may perform CBF and the central server may receive channel information from each of the APs in the set for each station associated with the set of C-APs (element 615). In some embodiments, the APs may pre-process the channel information from the primary and/or secondary stations. In other embodiments, the APs may relay channel information received in BF feedback reports from the group of stations.

The CBF logic circuitry of the central server may process the channel information from each of the stations based on channel sounding by each of the APs to estimate channel interference for the set of C-APs and the group of stations. Based on the channel interference estimated at each of the APs and each of the stations, from transmissions between APs and their primary stations, the CBF logic circuitry of the central server may determine one or more schedules for transmissions between APs and their primary stations (element 620). The schedules may include one or more access windows during which two or more of the APs are communicating with two or more of the stations simultaneously on the same sets of subcarriers or overlapping sets of the subcarriers of the channel.

The central server may then transmit the schedules to the APs in the set of C-APs to facilitate spatial reuse of the channel by the set of C-APs (element 630). In some embodiments, the central server may qualify the schedules based on potential movement of the stations. FIG. 7 depicts an embodiment of a flowchart 700 of a central server to BF a set of C-APs such as the central servers 1010 and 3060 illustrated in FIGs. 1 and 3. The flowchart 700 begins with an AP of a set of C-APs receiving a schedule from a central server for transmissions to and from primary stations of that AP (element 705). In some embodiments, the schedule may identify two or more of the APs in the set of C-APs to perform transmissions to primary stations simultaneously.

Each AP identified in the schedule may transmit a communication to the identified primary station of the AP simultaneously and on the same channel in accordance with the schedule (element 710). The simultaneous transmissions on the same channel may use the full bandwidth of the channel or may use the same or overlapping subchannels of the channel.

After transmitting the communications, each AP may receive concurrent responses from their primary stations on the channel (element 715). The concurrent responses on the same channel may use the full bandwidth of the channel or may use the same or overlapping subchannels of the channel.

Several embodiments have one or more potentially advantageous effects. For instance, transmitting, by each of the APs of the set, a collaborative beamforming (CBF) announcement frame sequentially in accordance with a predetermined sequence for the set, wherein the CBF announcement frame is addressed to a group of stations (STAs), may advantageously initiate CBF by multiple APs in the set of collaborative APs. Transmitting, by each of the APs of the set, a CBF announcement frame sequentially in accordance with a predetermined sequence for the set, wherein the CBF announcement frame is addressed to a group of STAs, may advantageously inform the group of STAs of the BF feedback report types for the primary STAs and for the secondary STAs, advantageously instruct the group of STAs to transmit BF feedback reports via OFDMA, and advantageously identify a BF report type with a rank one BF feedback indication for the one or more STAs. Such embodiments may advantageously reduce data traffic associated with CBF by reducing the feedback for secondary STAs.

EXAMPLES OF FURTHER EMBODIMENTS

The following examples pertain to further embodiments. Specifics in the examples may be used anywhere in one or more embodiments.

Example 1 is an apparatus to beamform as part of a set of collaborative access points (C-APs), the apparatus comprising: medium access control (MAC) logic circuitry to generate a collaborative beamforming (CBF) announcement frame to initiate CBF, wherein the CBF announcement frame is addressed to a group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; and a physical layer device coupled with the MAC logic to transmit the CBF announcement frame; to transmit a channel sounding packet after transmission of the CBF announcement frame; and to receive, after transmitting the channel sounding packet, a beamforming feedback report from each of the stations in an order indicated in the CBF announcement frame. In Example 2, the apparatus of Example 1, further comprising a processor, a memory coupled with the processor, a radio coupled with the physical layer device, and one or more antennas coupled with the radio to transmit the CBF announcement frame. In Example 3, the apparatus of Example 1 can optionally include the MAC logic circuitry is configured to trigger transmission of beamforming feedback reports from each station of the group of stations associated with the apparatus as a primary station prior to triggering transmission of beamforming feedback reports from each station of the group of stations associated with the apparatus as a secondary station. In Example 4, the apparatus of Example 1 can optionally include the CBF Announcement frame comprises fields to identify an identifier for each of the access points in the set. In Example 5, the apparatus of Example 1 can optionally include the CBF Announcement frame comprises fields to identify the order in which each of the stations are instructed to respond to channel sounding packet with the beamforming feedback report. In Example 6, the apparatus of Example 1 can optionally include the CBF announcement frame comprises instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA). In Example 7, the apparatus of Example 1, further comprising physical layer logic circuitry coupled with the physical layer device to receive beamforming feedback reports from two or more stations in the group of stations simultaneously on different subchannels of a channel. In Example 8, the apparatus of Example 1 can optionally include the CBF Announcement frame comprises one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on two or more subchannels.

In Example 9, the apparatus of Example 1 can optionally include the CBF Announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a primary access point, and to identify a beamforming report type with a full rank beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the full rank beamforming feedback indication provides a full rank, channel state information. In Example 10, the apparatus of Example 1 can optionally include the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information, wherein the rank one. In Example 11, a system comprising the apparatus of any one of Examples 1-12 can optionally include logic circuitry to determine a schedule for simultaneous transmissions by the C-APs on the same channel based on channel information from the BF feedback reports.

Example 12 is a method to beamform as part of a set of collaborative access points (C-APs), the method comprising: generating, by an access point of the set of C-APs, a collaborative beamforming (CBF) announcement frame to initiate CBF, wherein the CBF announcement frame is addressed to a group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; transmitting, by the access point, the CBF announcement frame; transmitting, by the access point, a channel sounding packet after transmission of the CBF announcement frame; and receiving, by the access point, after transmitting the channel sounding packet, a beamforming feedback report from each of the stations in an order indicated in the CBF announcement frame. In Example 13, the method of Example 12, further comprising receiving, by the access point and from a central server, an indication to assign the access point to the set. In Example 14, the method of Examplel2, further comprising transmitting channel information from the beamforming feedback reports received from each station to a central server. In Example 15, the method of Example 12 can optionally include the CBF Announcement frame comprises fields to identify an identifier for each of the access points in the set. In Example 15, the method of Example 12 can optionally include the CBF Announcement frame comprises fields to identify the order in which each of the stations are instructed to respond to channel sounding with the beamforming feedback report.

In Example 17, the method of Example 12 can optionally include generating the CBF announcement frame comprising instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and wherein receiving the beamforming feedback report comprises receiving beamforming feedback reports from two or more stations in the group of stations simultaneously. In Example 18, the method of Example 12 can optionally include generating the CBF Announcement frame comprising one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on two or more subchannels. In Example 19, the method of Example 12 can optionally include each station of the group of stations is associated with one of the C-APs as a primary access point and other access points of the set that can be sensed at each station as secondary access points. In Example 20, the method of Example 12 can optionally include generating the CBF Announcement frame comprising fields to identify associations of one or more stations of the group with the access point as a primary access point, and to identify a beamforming report type with a full rank beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the full rank beamforming feedback indication provides full rank, channel state information. In Example 21, the method of Example 12 can optionally include generating the CBF Announcement frame comprising fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information matrix. Example 22 is a storage medium for storing a computer program of any one of Examples 12-21. And example 23 is a computer program for causing at least one processor to perform any one of Examples 12-21.

Example 24 is an apparatus to beamform as part of a set of collaborative access points (C- APs), the apparatus comprising: a means for generating, by an access point of the set of C-APs, a collaborative beamforming (CBF) announcement frame to initiate CBF, wherein the CBF announcement frame is addressed to a group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; a means for transmitting, by the access point, the CBF announcement frame; a means for transmitting, by the access point, a channel sounding packet after transmission of the CBF announcement frame; and a means for receiving, by the access point, after transmitting the channel sounding packet, a beamforming feedback report from each of the stations in an order indicated in the CBF announcement frame. In Example 25, the apparatus of Example 24, further comprising a means for receiving, by the access point and from a central server, an indication to assign the access point to the set. In Example 26, the apparatus of Example 24, further comprising a means for transmitting channel information from the beamforming feedback reports received from each station to a central server. In Example 27, the apparatus of Example 24 can optionally include the CBF Announcement frame comprises fields to identify an identifier for each of the access points in the set. In Example 28, the apparatus of Example 24 can optionally include the CBF Announcement frame comprises fields to identify the order in which each of the stations are instructed to respond to channel sounding with the beamforming feedback report.

In Example 29, the apparatus of Example 24 can optionally include a means for generating the CBF announcement frame comprising instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and wherein receiving the beamforming feedback report comprises receiving beamforming feedback reports from two or more stations in the group of stations simultaneously. In Example 30, the apparatus of Example 24 can optionally include a means for generating the CBF Announcement frame comprising one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on two or more subchannels. In Example 31, the apparatus of Example 24 can optionally include each station of the group of stations is associated with one of the C-APs as a primary access point and other access points of the set that can be sensed at each station as secondary access points. In Example 32, the apparatus of Example 24 can optionally include a means for generating the CBF Announcement frame comprising fields to identify associations of one or more stations of the group with the access point as a primary access point, and to identify a beamforming report type with a full rank beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the full rank beamforming feedback indication provides full rank, channel state information.

In Example 33, the apparatus of Example 24 can optionally include a means for generating the CBF Announcement frame comprising fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information matrix.

Example 34 is a computer program product comprising: a non-transitory medium containing instructions to beamform as part of a set of collaborative access points (C-APs), wherein the instructions, when executed by a processor, causes the processor to perform operations, the operations comprising: generating a collaborative beamforming (CBF) announcement frame to initiate CBF, wherein the CBF announcement frame is addressed to a group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; transmitting the CBF announcement frame; transmitting a channel sounding packet after transmission of the CBF announcement frame; and receiving, after transmitting the channel sounding packet, a beamforming feedback report from each of the stations in an order indicated in the CBF announcement frame. In Example 35, the computer program product of Example 34 can optionally include the operations further comprise receiving, by the access point and from a central server, an indication to assign the access point to the set. In Example 36, the computer program product of Example 34 can optionally include the operations further comprise transmitting channel information from the beamforming feedback reports received from each station to a central server. In Example 37, the computer program product of Example 34 can optionally include the CBF Announcement frame comprises fields to identify an identifier for each of the access points in the set.

In Example 38, the computer program product of Example 34 can optionally include the CBF

Announcement frame comprises fields to identify the order in which each of the stations are instructed to respond to channel sounding with the beamforming feedback report. In Example 39, the computer program product of Example 34 can optionally include generating the CBF announcement frame comprising instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and wherein receiving the beamforming feedback report comprises receiving beamforming feedback reports from two or more stations in the group of stations simultaneously. In Example 40, the computer program product of Example 34 can optionally include generating the CBF Announcement frame comprising one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on two or more subchannels. In Example 41, the computer program product of Example 34 can optionally include each station of the group of stations is associated with one of the C-APs as a primary access point and other access points of the set that can be sensed at each station as secondary access points. In Example 42, the computer program product of Example 34 can optionally include generating the CBF Announcement frame comprising fields to identify associations of one or more stations of the group with the access point as a primary access point, and to identify a beamforming report type with a full rank beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the full rank beamforming feedback indication provides full rank, channel state information.

In Example 43, the computer program product of Example 34 can optionally include generating the CBF Announcement frame comprising fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information matrix.

Example 44 is an apparatus to beamform a set of collaborative access points (C-APs), the apparatus comprising: medium access control (MAC) logic circuitry to receive, as a station of a group of stations associated with the set of C-APs, a collaborative beamforming (CBF) announcement frame from each access point in the set of C-APs, wherein the CBF announcement frame is addressed to the group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; and a physical layer device coupled with the MAC logic circuitry to receive, from each access point in the set of C-APs, a channel sounding packet on the channel in accordance with the order of channel sounding; to calculate channel state information based on receipt of the channel sounding packet; and to transmit a beamforming feedback report in response to receipt of the channel sounding packet. In Example 45, the apparatus of Example 44, further comprising a processor, a memory coupled with the processor, a radio coupled with the physical layer device, and one or more antennas coupled with the radio to transmit the CBF announcement frame. In Example 46, the apparatus of Example 44 can optionally include the MAC logic circuitry comprises logic to associate with all access points in the set of C-APs that are within a wireless communications range of the station, the logic to associate with a first access point in the set of C-APs as a primary station and to associate with all access points in the set of C-APs that are within a wireless communications range of the station except the first access point as a secondary station. In Example 47, the apparatus of Example 44 can optionally include the MAC logic circuitry comprises logic to associate with one of the access points in the set of C-APs as a primary access point and all other access points in the set of C-APs that are within a wireless communications range of the station as secondary access points. In Example 48, the apparatus of Example 44 can optionally include the CBF announcement frame comprises instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and to transmit the beamforming feedback reports from the station and one or more other stations in the group of stations simultaneously. In Example 49, the apparatus of Example 44 can optionally include the CBF announcement frame comprises one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on the two or more subchannels.

In Example 50, the apparatus of Example 44 can optionally include the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a primary access point, and to identify a beamforming report type with a full rank beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the full rank beamforming feedback indication provides full rank, channel state information. In Example 51, the apparatus of Example 44 can optionally include the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information. In Example 52, A system comprising the apparatus of any one of Examples 44-51 can optionally include the system further comprises logic circuitry to determine a schedule for simultaneous transmissions by the C-APs based on channel information from the BF feedback reports.

Example 53 is a method to beamform a set of collaborative access points (C-APs), the method comprising: receiving, by a station of a group of stations associated with the set of C-APs, a collaborative beamforming (CBF) announcement frame from each access point in the set of C-APs, wherein the CBF announcement frame is addressed to the group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; receiving, by the station from each access point in the set of C-APs, a channel sounding packet on the channel in accordance with the order of channel sounding; calculating channel state information based on receipt of the channel sounding packet; and transmitting, by the station, a beamforming feedback report in response to receipt of the channel sounding packet. In Example 54, the method of Example 53, further comprising associating, by the station, with one of the access points in the set of C-APs as a primary access point and all other access points in the set of C-APs that are within a wireless communications range of the station as secondary access points. In Example 55, the method of Example 53 can optionally include the CBF announcement frame comprises instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and wherein transmitting the beamforming feedback report comprises transmitting beamforming feedback reports from the station and one or more other stations in the group of stations simultaneously.

In Example 56, the method of Example 53 can optionally include the CBF announcement frame comprises one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on the two or more subchannels. In Example 57, the method of Example 53 can optionally include the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a primary access point, and to identify a beamforming report type with a full rank beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the full rank beamforming feedback indication provides full rank, channel state information. In Example 58, the method of Example 53 can optionally include the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information. Example 59 is a storage medium for storing a computer program of any one of Examples 53-58. Example 60 is a computer program for causing at least one processor to perform any one of Examples 53-58.

Example 61 is an apparatus to beamform a set of collaborative access points (C-APs), the method comprising: a means for receiving, by a station of a group of stations associated with the set of C-APs, a collaborative beamforming (CBF) announcement frame from each access point in the set of C-APs, wherein the CBF announcement frame is addressed to the group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; a means for receiving, by the station from each access point in the set of C- APs, a channel sounding packet on the channel in accordance with the order of channel sounding; a means for calculating channel state information based on receipt of the channel sounding packet; and a means for transmitting, by the station, a beamforming feedback report in response to receipt of the channel sounding packet. In Example 62, the apparatus of Example 61, further comprising a means for associating, by the station, with one of the access points in the set of C-APs as a primary access point and all other access points in the set of C-APs that are within a wireless communications range of the station as secondary access points.

In Example 63, the apparatus of Example 61 can optionally include the CBF announcement frame comprises instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and wherein transmitting the beamforming feedback report comprises transmitting beamforming feedback reports from the station and one or more other stations in the group of stations simultaneously. In Example 64, the apparatus of Example 61 can optionally include the CBF announcement frame comprises one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on the two or more subchannels. In Example 65, the apparatus of Example 61 can optionally include the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a primary access point, and to identify a beamforming report type with a full rank beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the full rank beamforming feedback indication provides full rank, channel state information. In Example 66, the apparatus of Example 61 can optionally include the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information.

Example 67 is a computer program product comprising: a non-transitory medium containing instructions to beamform a set of collaborative access points (C-APs), wherein the instructions, when executed by a processor, causes the processor to perform operations, the operations comprising: receiving, by a station of a group of stations associated with the set of C-APs, a collaborative beamforming (CBF) announcement frame from each access point in the set of C-APs, wherein the CBF announcement frame is addressed to the group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C- APs; receiving, by the station from each access point in the set of C-APs, a channel sounding packet on the channel in accordance with the order of channel sounding; and transmitting, by the station, a beamforming feedback report in response to receipt of the channel sounding packet, the beamforming feedback report comprising channel state information calculated based on receipt of the sounding packet. In Example 68, the computer program product of Example 67, further comprising receiving a beamforming report poll from each access point in the set of C-APs to trigger transmission of the beamforming feedback report to each access point in the set of C-APs. In Example 69, the computer program product of Example 67, further comprising associating, by the station, with one of the access points in the set of C-APs as a primary access point and all other access points in the set of C-APs that are within a wireless communications range of the station as secondary access points.

In Example 70, the computer program product of Example 67 can optionally include the CBF announcement frame comprises one or more fields to indicate an order of response to the channel sounding for each station in the group of stations. In Example 71, the computer program product of Example 67 can optionally include the CBF announcement frame comprises instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and wherein transmitting the beamforming feedback report comprises transmitting beamforming feedback reports from the station and one or more other stations in the group of stations simultaneously. In Example 72, the computer program product of Example 67 can optionally include the CBF announcement frame comprises one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on the two or more subchannels. In Example 73, the computer program product of Example 67 can optionally include the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a primary access point, and to identify a beamforming report type with a full rank beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the full rank beamforming feedback indication provides full rank, channel state information. In Example 74, the computer program product of Example 67 can optionally include the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information.

Example 75 is an apparatus to schedule simultaneous transmissions on a channel by a set of collaborative access points (C-APs), the apparatus comprising: a logic circuitry to receive channel information from a group of stations from each of the set of C-APs based on channel sounding packets transmitted by each of the set of C-APs; scheduling circuitry coupled with the logic circuitry to process the channel information to determine a schedule for simultaneous transmissions between two or more access points of the set of C-APs and two or more stations of the group of stations, wherein the scheduling circuitry determines the schedule based on channel interference caused at each of the stations by each of the access points in the set of C-APs and channel directivity associated with each of the simultaneous transmissions in the schedule; and a physical layer device coupled with the scheduling circuitry to transmit the schedule to the two or more access points. In Example 76, the apparatus of Example 75, further comprising a processor, memory, and a communications interface to couple with each access point in the set of C-APs. In Example 77, the apparatus of Example 76 can optionally include the communications interface comprises a wireless communications interface to wirelessly connect to one or more of the access points in the set of C-APs. In Example 78, the apparatus of Example 76 can optionally include the communications interface comprises a wired communications interface to communicate with one or more of the access points in the set of C-APs.

Example 79 is a method to schedule simultaneous transmissions on a channel by a set of collaborative access points (C-APs), the method comprising: for each access point in the set of C- APs: receiving, by a central server, channel information from a group of stations from each of the set of C-APs based on channel sounding packets transmitted by each of the set of C-APs; processing, by the central server, the channel information to determine a schedule for simultaneous transmissions between two or more access points of the set of C-APs and two or more stations of the group of stations, wherein the scheduling circuitry determines the schedule based on channel interference caused at each of the stations by each of the access points in the set of C-APs and channel directivity associated with each of the simultaneous transmissions in the schedule; and transmitting, by the central server, the schedule to the two or more access points. In Example 80, the method of Example 79 can optionally include transmitting the schedule wirelessly via a communications interface. In Example 81, the method of Example 79 can optionally include transmitting the schedule via a communications interface to communicate with one or more of the access points in the set of C-APs. Example 82 is a storage medium for storing a computer program of any one of Examples 79-81. Example 83 is computer program for causing at least one processor to perform any one of Examples 79-81.

Example 84 is an apparatus to schedule simultaneous transmissions on a channel by a set of collaborative access points (C-APs), the method comprising: for each access point in the set of C- APs: a means for receiving, by a central server, channel information from a group of stations from each of the set of C-APs based on channel sounding packets transmitted by each of the set of C-APs; a means for processing, by the central server, the channel information to determine a schedule for simultaneous transmissions between two or more access points of the set of C-APs and two or more stations of the group of stations, wherein the scheduling circuitry determines the schedule based on channel interference caused at each of the stations by each of the access points in the set of C-APs and channel directivity associated with each of the simultaneous transmissions in the schedule; and a means for transmitting, by the central server, the schedule to the two or more access points. In Example 85, the apparatus of Example 84, further comprising a processor, memory, and a communications interface to couple with each access point in the set of C-APs. Example 86 is a computer program product comprising: a non-transitory medium containing instructions to schedule simultaneous transmissions on a channel by a set of collaborative access points (C-APs), wherein the instructions, when executed by a processor, causes the processor to perform operations, the operations comprising: receiving channel information from a group of stations from each of the set of C-APs based on channel sounding packets transmitted by each of the set of C-APs; processing the channel information to determine a schedule for simultaneous transmissions between two or more access points of the set of C-APs and two or more stations of the group of stations, wherein the scheduling circuitry determines the schedule based on channel interference caused at each of the stations by each of the access points in the set of C-APs and channel directivity associated with each of the simultaneous transmissions in the schedule; and transmitting the schedule to the two or more access points. In Example 87, the computer program product of Example 86 can optionally include transmitting the schedule wirelessly via a wireless communications interface. In Example 88, the computer program product of Example 86 can optionally include transmitting the schedule via a wired communications interface.

Several embodiments comprise central servers, access points (APs), and/or stations (STAs) such as modems, routers, switches, servers, workstations, netbooks, mobile devices (Laptop, Smart Phone, Tablet, and the like), sensors, meters, controls, instruments, monitors, home or office appliances, Internet of Things (IoT) gear (watches, glasses, headphones, and the like), and the like. Some embodiments may provide, e.g., indoor and/or outdoor "smart" grid and sensor services. In various embodiments, these devices relate to specific applications such as healthcare, home, commercial office and retail, security, and industrial automation and monitoring applications, as well as vehicle applications (automobiles, self-driving vehicles, airplanes, and the like), and the like.

Another embodiment is implemented as a program product for implementing systems and methods described with reference to FIGs. 1-7. Some embodiments can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment containing both hardware and software elements. One embodiment is implemented in software, which includes but is not limited to firmware, resident software, microcode, etc.

Furthermore, embodiments can take the form of a computer program product (or machine- accessible product) accessible from a computer-usable or computer-readable medium providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer-usable or computer readable medium can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.

The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device). Examples of a computer-readable medium include a semiconductor or solid-state memory, magnetic tape, a removable computer diskette, a random- access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and an optical disk. Current examples of optical disks include compact disk - read only memory (CD-ROM), compact disk - read/write (CD-R/W), and DVD.

A data processing system suitable for storing and/or executing program code will include at least one processor coupled directly or indirectly to memory elements through a system bus. The memory elements can include local memory employed during actual execution of the program code, bulk storage, and cache memories which provide temporary storage of at least some program code to reduce the number of times code must be retrieved from bulk storage during execution.

Logic circuitry, devices, and interfaces herein described may perform functions implemented in hardware and also implemented with code executed on one or more processors. Circuitry may refer to one or more circuits. Each circuit may perform a particular function. A circuit of the circuitry may comprise discrete electrical components interconnected with one or more conductors, an integrated circuit, a chip package, a chip set, memory, or the like. Integrated circuits include circuits created on a substrate such as a silicon wafer and may comprise components. Furthermore, integrated circuits, chip packages, and chipsets may comprise one or more processors.

Processors may receive signals such as instructions and/or data at the input(s) and process the signals to generate the at least one output. A processor may comprise circuits to perform one or more sub-functions implemented to perform the overall function of the processor. One example of a processor is a state machine or an application-specific integrated circuit (ASIC) that includes at least one input and at least one output. A state machine may manipulate the at least one input to generate the at least one output by performing a predetermined series of serial and/or parallel manipulations or transformations on the at least one input.

Memory may comprise any storage arrangement including optical media, magnetic media, and circuitry with one or more circuits such as buffers, cache, flash, dynamic random access memory, programmable read only memory, and the like. Furthermore, code may comprise software, firmware, microcode, or any other form of instructions and/or data designed to accomplish functionality. The logic as described above may be part of the design for an integrated circuit chip. The chip design is created in a graphical computer programming language, and stored in a computer storage medium (such as a disk, tape, physical hard drive, or virtual hard drive such as in a storage access network). If the designer does not fabricate chips or the photolithographic masks used to fabricate chips, the designer transmits the resulting design by physical means (e.g., by providing a copy of the storage medium storing the design) or electronically (e.g., through the Internet) to such entities, directly or indirectly. The stored design is then converted into the appropriate format (e.g., GDSII) for the fabrication.

The resulting integrated circuit chips can be distributed by the fabricator in raw wafer form (that is, as a single wafer that has multiple unpackaged chips), as a bare die, or in a packaged form. In the latter case, the chip is mounted in a single chip package (such as a plastic carrier, with leads that are affixed to a motherboard or other higher level carrier) or in a multichip package (such as a ceramic carrier that has either or both surface interconnections or buried interconnections). In any case, the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product.

Claims

WHAT IS CLAIMED IS:

1. An apparatus to beamform as part of a set of collaborative access points (C-APs), the apparatus comprising:

medium access control (MAC) logic circuitry to generate a collaborative beamforming (CBF) announcement frame to initiate CBF, wherein the CBF announcement frame is addressed to a group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; and

a physical layer device coupled with the MAC logic circuitry to transmit the CBF announcement frame; to transmit a channel sounding packet after transmission of the CBF announcement frame; and to receive, after transmitting the channel sounding packet, a beamforming feedback report from each of the stations in an order indicated in the CBF announcement frame.

2. The apparatus of claim 1, further comprising a processor, a memory coupled with the processor, a radio coupled with the physical layer device, and one or more antennas coupled with the radio to transmit the CBF announcement frame.

3. The apparatus of claim 1, wherein the MAC logic circuitry is configured to trigger transmission of beamforming feedback reports from each station of the group of stations associated with the apparatus as a primary station prior to triggering transmission of beamforming feedback reports from each station of the group of stations associated with the apparatus as a secondary station.

4. The apparatus of claim 1, wherein the CBF announcement frame comprises instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA).

5. A method to beamform as part of a set of collaborative access points (C-APs), the method comprising:

generating, by an access point of the set of C-APs, a collaborative beamforming (CBF) announcement frame to initiate CBF, wherein the CBF announcement frame is addressed to a group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; transmitting, by the access point, the CBF announcement frame;

transmitting, by the access point, a channel sounding packet after transmission of the CBF announcement frame; and

receiving, by the access point, after transmitting the channel sounding packet, a beamforming feedback report from each of the stations in an order indicated in the CBF announcement frame.

The method of claim 5, wherein generating the CBF announcement frame comprises generating the CBF Announcement frame comprising one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on two or more subchannels.

The method of claim 5, wherein each station of the group of stations is associated with one of the C-APs as a primary access point and other access points of the set that can be sensed at each station as secondary access points.

The method of claim 5, wherein generating the CBF announcement frame comprises generating the CBF Announcement frame comprising fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information matrix, wherein the rank one, channel state information matrix comprises channel state information based on one beamforming eigenvector.

A computer program product comprising:

a non-transitory medium containing instructions to beamform as part of a set of collaborative access points (C-APs), wherein the instructions, when executed by a processor, causes the processor to perform operations, the operations comprising: generating a collaborative beamforming (CBF) announcement frame to initiate CBF, wherein the CBF announcement frame is addressed to a group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs;

transmitting the CBF announcement frame;

transmitting a channel sounding packet after transmission of the CBF announcement frame; and

receiving, after transmitting the channel sounding packet, a beamforming feedback report from each of the stations in an order indicated in the CBF announcement frame.

The computer program product of claim 9, wherein the operations further comprise transmitting channel information from the beamforming feedback reports received from each station to a central server.

The computer program product of claim 9, wherein the CBF Announcement frame comprises fields to identify the order in which each of the stations are instructed to respond to channel sounding with the beamforming feedback report.

The computer program product of claim 9, wherein generating the CBF announcement frame comprises generating the CBF announcement frame comprising instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and wherein receiving the beamforming feedback report comprises receiving beamforming feedback reports from two or more stations in the group of stations simultaneously.

An apparatus to beamform a set of collaborative access points (C-APs), the apparatus comprising:

medium access control (MAC) logic circuitry to receive, as a station of a group of stations associated with the set of C-APs, a collaborative beamforming (CBF) announcement frame from each access point in the set of C-APs, wherein the CBF announcement frame is addressed to the group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs; and a physical layer device coupled with the MAC logic circuitry to receive, from each access point in the set of C-APs, a channel sounding packet on the channel in accordance with the order of channel sounding; to calculate channel state information based on receipt of the channel sounding packet; and to transmit a beamforming feedback report in response to receipt of the sounding packet.

The apparatus of claim 13, further comprising a processor, a memory coupled with the processor, a radio coupled with the physical layer device, and one or more antennas coupled with the radio to transmit the CBF announcement frame.

The apparatus of claim 13, wherein the MAC logic circuitry comprises logic to associate with a first access point in the set of C-APs as a primary station and to associate with all access points in the set of C-APs that are within a wireless communications range of the station except the first access point as a secondary station.

The apparatus of claim 13, wherein the CBF announcement frame comprises instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and to transmit the beamforming feedback reports from the station and one or more other stations in the group of stations simultaneously.

A method to beamform a set of collaborative access points (C-APs), the method comprising: receiving, by a station of a group of stations associated with the set of C-APs, a collaborative beamforming (CBF) announcement frame from each access point in the set of C-APs, wherein the CBF announcement frame is addressed to the group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs;

receiving, by the station from each access point in the set of C-APs, a channel sounding packet on the channel in accordance with the order of channel sounding;

calculating channel state information based on receipt of the channel sounding packet; and transmitting, by the station, a beamforming feedback report in response to receipt of the channel sounding packet. The method of claim 17, further comprising associating, by the station, with one of the access points in the set of C-APs as a primary access point and all other access points in the set of C- APs that are within a wireless communications range of the station as secondary access points.

The method of claim 17, wherein the CBF announcement frame comprises one or more fields to assign two or more subchannels to two or more of the stations to facilitate simultaneous transmission of beamforming feedback reports from the two or more of the stations on the two or more subchannels.

The method of claim 17, wherein the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a secondary access point, and to identify a beamforming report type with a rank one beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the rank one beamforming feedback indication provides a rank one, channel state information.

A computer program product comprising:

a non-transitory medium containing instructions to beamform a set of collaborative access points (C-APs), wherein the instructions, when executed by a processor, causes the processor to perform operations, the operations comprising:

receiving, by a station of a group of stations associated with the set of C-APs, a collaborative beamforming (CBF) announcement frame from each access point in the set of C-APs, wherein the CBF announcement frame is addressed to the group of stations, wherein the CBF announcement frame comprises an indication of an order of channel sounding by each access point in the set of C-APs;

receiving, by the station from each access point in the set of C-APs, a channel sounding packet on the channel in accordance with the order of channel sounding; and

transmitting, by the station, a beamforming feedback report in response to receipt of the channel sounding packet, the beamforming feedback report comprising channel state information calculated based on receipt of the sounding packet. The computer program product of claim 21, wherein the CBF announcement frame comprises one or more fields to indicate an order of response to the channel sounding for each station in the group of stations.

The computer program product of claim 21, wherein the CBF announcement frame comprises instructions for the group of stations to transmit beamforming feedback reports via Orthogonal Frequency Division Multiple Access (OFDMA) and wherein transmitting the beamforming feedback report comprises transmitting beamforming feedback reports from the station and one or more other stations in the group of stations simultaneously.

The computer program product of claim 21, wherein the CBF announcement frame comprises fields to identify associations of one or more stations of the group with the access point as a primary access point, and to identify a beamforming report type with a full rank beamforming feedback indication for the one or more stations, wherein the beamforming feedback report associated with the full rank beamforming feedback indication provides full rank, channel state information.

An apparatus to schedule simultaneous transmissions on a channel by a set of collaborative access points (C-APs), the apparatus comprising:

a logic circuitry to receive channel information from a group of stations from each of the set of C-APs based on channel sounding packets transmitted by each of the set of C-APs; scheduling circuitry coupled with the logic circuitry to process the channel information to determine a schedule for simultaneous transmissions between two or more access points of the set of C-APs and two or more stations of the group of stations, wherein the scheduling circuitry determines the schedule based on channel interference caused at each of the stations by each of the access points in the set of C-APs and channel directivity associated with each of the simultaneous transmissions in the schedule; and a physical layer device coupled with the scheduling circuitry to transmit the schedule to the two or more access points.

The apparatus of claim 25, further comprising a processor, memory, and a communications interface to couple with each access point in the set of C-APs. A method to schedule simultaneous transmissions on a channel by a set of collaborative access points (C-APs), the method comprising:

receiving, by a central server, channel information from a group of stations from each of the set of C-APs based on channel sounding packets transmitted by each of the set of C- APs;

processing, by the central server, the channel information to determine a schedule for simultaneous transmissions between two or more access points of the set of C-APs and two or more stations of the group of stations, wherein the scheduling circuitry determines the schedule based on channel interference caused at each of the stations by each of the access points in the set of C-APs and channel directivity associated with each of the simultaneous transmissions in the schedule; and

transmitting, by the central server, the schedule to the two or more access points.

The method of claim 27, wherein transmitting the schedule comprises transmitting the schedule wirelessly via a communications interface.

A computer program product comprising:

a non-transitory medium containing instructions to schedule simultaneous transmissions on a channel by a set of collaborative access points (C-APs), wherein the instructions, when executed by a processor, causes the processor to perform operations, the operations comprising:

receiving channel information from a group of stations from each of the set of C-APs based on channel sounding packets transmitted by each of the set of C-APs;

processing the channel information to determine a schedule for simultaneous transmissions between two or more access points of the set of C-APs and two or more stations of the group of stations, wherein the scheduling circuitry determines the schedule based on channel interference caused at each of the stations by each of the access points in the set of C-APs and channel directivity associated with each of the simultaneous transmissions in the schedule; and

transmitting the schedule to the two or more access points.

The computer program product of claim 29, wherein transmitting the schedule comprises transmitting the schedule wirelessly via a wireless communications interface.