METHOD AND SYSTEM FOR EXPLICIT AP-TO-AP SOUNDING IN AN 802.11 NETWORK
A method of one AP accessing a channel occupied by a neighboring AP within CCA range, by acquiring channel knowledge via performing cooperative sounding and setting a null towards the neighboring AP, under certain conditions verifications, is provided herein. The method may include: transmitting and receive signals via a plurality of radio circuitries connected to plurality of antennas; monitoring signals received by the radio circuitries and generating a list of neighboring co-channel access points that each has plurality of antennas and are further located within a clear channel assessment (CCA) range of the access point; and instructing the radio circuitries to transmit a sounding sequence to the list of neighboring access points, and receive Channel State Information (CSI).
1 . An access point (AP) comprising:
a plurality of antennas;
a plurality of radio circuitries configured to transmit and receive signals via the plurality of antennas; and
a baseband processor configured to monitor the signals received by the radio circuitries and generates a list of neighboring co-channel access points (APs), each is further located within a clear channel assessment (CCA) range of said access point,
wherein the baseband processor is further configured to establish a subgroup of neighboring co-channel APs which agree to join an access point sounding set (APSS), instruct the radio circuitries to transmit a sounding sequence to said APSS, and receive channel state information (CSI) therefrom.
2 . The access point according to claim 1 , wherein the baseband processor is further configured to set weights on the radio circuitries to produce a null at one or more antennas of said APSS which currently transmits on a same frequency channel and download a packet to a station (STA), or a group of STAs.
3 . The access point according to claim 2 , wherein the null weights are determined via explicit sounding process invoked between said access point and each of the APSS, based on APSS Null Data Packet (NDP) announcement by said AP and response by APSS.
4 . The access point according to claim 3 , wherein the AP sends an APSS NDP announcement to all APs in APSS, followed by an NDP, and a V compressed response from a first neighboring AP and a series of poll requests to a next neighboring AP and a corresponding V compressed response, until all APs in APSS are polled and all V compressed responses are consummated, wherein V is a compressed matrix representing the channel response.
5 . The access point according to claim 3 , wherein the APSS NDP announcement and NDP comprise an APSS ID field replacing in the IEEE 802.11ac MU MIMO sounding protocol the STA ID field.
6 . The access point according to claim 3 , wherein the Poll Request field is retrofitted to address a neighboring APs rather than STAs in the IEEE 802.11ac MU MIMO sounding protocol.
7 . A method of performing an explicit sounding process to neighboring access points (APs) by a beamformer access point (AP) comprising:
transmitting and receiving signals via a plurality of radio circuitries connected to a plurality of antennas;
monitoring the signals received by the radio circuitries and generating a list of neighboring co-channel access points, each being located within a clear channel assessment (CCA) range of the access point;
establishing a subgroup of neighboring co-channel APs which agree to join an access point sounding set (APSS); and
instructing the radio circuitries to transmit a sounding sequence to the list of neighboring co-channel access points, and receive channel state information (CSI) from APs in APSS.
8 . The method according to claim 7 , wherein the baseband processor is further configured to set weights on the radio circuitries to produce a null at one or more antennas of said APSS which currently transmits on a same frequency channel and download a packet to a station (STA), or a group of STAs.
9 . The method according to claim 8 , wherein the null weights are determined via explicit sounding process invoked between said access point and each of the APSS, based on APSS Null Data Packet (NDP) announcement by said AP and response by APSS.
10 . The method according to claim 9 , wherein the AP sends an APSS NDP announcement to all APs in APSS, followed by an NDP, and a V compressed response from a first neighboring AP and a series of poll requests to a next neighboring AP and a corresponding V compressed response, until all APs in APSS are polled and all V compressed responses are consummated, wherein V is a compressed matrix representing the channel response.
11 . The method according to claim 9 , wherein the APSS NDP announcement and NDP comprise an APSS ID field replacing in the IEEE 802.11ac MU MIMO sounding protocol the STA ID field.
12 . The method according to claim 9 , wherein the Poll Request field is retrofitted to address a neighboring APs rather than STAs in the IEEE 802.11ac MU MIMO sounding protocol.