Multi-beam co-channel Wi-Fi access point

• US 9,385,793 B2
• Filed: 03/16/2015
• Issued: 07/05/2016
• Est. Priority Date: 02/13/2013
• Status: Active Grant

• Current Assignee: Magnolia Broadband Incorporated
• Original Assignee: Magnolia Broadband Incorporated
• Inventors: Harel, Haim, Chen, Phil F., Kludt, Kenneth, Jeffery, Stuart S., Wang, Sherwin J., Abreu, Eduardo
• Primary Examiner(s): Phan, Man
• Assistant Examiner(s): KAVLESKI, RYAN C
• Application Number:
  US14/658,986
• Publication Number:
  US 20150249487A1
• Time in Patent Office: 477 Days
• Field of Search: 370/338, 375/346, 455/63.1, 455/562.1
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/043 using best eigenmode, e.g. beam forming or beam steering
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04W 36/22 for handling the traffic
• CPC Class Codes: H04W 74/0816 with collision avoidance
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A system and method for providing multi-beam Wi-Fi access points. The system includes one or more Wi-Fi transmit antennas beamformers; one or more Wi-Fi receive antennas or receive beamformers; and a number N of co-channel Wi-Fi access points (APs) and a number of M non co-channel APS, where all APs comply with IEEE802.11xx standard, connected to the Wi-Fi transmit antennas beamformers, wherein the Wi-Fi transmit antennas beamformers are configured to produce a plurality of non spatially adjacent beams of a common frequency, directed at a plurality of Wi-Fi user equipment (UE) such that the directional beams are sufficiently isolated from each other, and at least some of the Wi-Fi UEs communicate simultaneously with the plurality of Wi-Fi access points.

Claims

1. A system comprising:

one or more Wi-Fi transmit beamformers, each comprising a plurality of transmit antennas;

one or more Wi-Fi receive beamformers, each comprising a plurality of receive antennas; and

a number N of co-located co-channel Wi-Fi access points (APs), each of said Wi-Fi APs having Wi-Fi transmitters and receivers and connected to the Wi-Fi transmit beamformers and the Wi-Fi receive beamformers,

wherein the Wi-Fi transmit beamformers and the Wi-Fi receive beamformers are configured to produce a plurality of directional beams of a common frequency, directed at a plurality of Wi-Fi user equipment (UE) devices such that the directional beams are sufficiently isolated from each other, so that at least some of the Wi-Fi UE devices communicate simultaneously with the plurality of Wi-Fi APS,

wherein beam patterns of the transmit antennas exhibit contaminating transmit signals being an accumulated contribution of side lobes and back lobes, wherein the system further comprises amplitude/phase modules associated with said transmit antennas and null transmit module configured to receive a difference between signals received by said receive antenna and said contaminating transmit signals detected in the receiving circuitry and control said amplitude/phase modules so that transmit signal component in the receiver are reduced using accurate destructive interference manifested via closed loop.

2. The system according to claim 1, wherein the Wi-Fi AP protocol has a basic medium contention in which Wi-Fi devices packets are not synchronized or delayed and wherein a distributed coordination function is applied via at least one of:

carrier sense and random back-off, for collisions avoidance.

3. The system according to claim 1, wherein signals generated by the N co-channel Wi-Fi transmitters are sufficiently isolated from N respective receivers such that a transmission power of a signal received by N−

1 of the N co-channel Wi-Fi transmitters is lower than a white Gaussian noise level present at the N respective receivers.

4. The system according to claim 3, wherein the isolation is achieved by a spatial separation that attenuates the transmitted signal of the directional beams by at least 100 dB.

5. The system according to claim 3, wherein the receive antennas and/or the transmit antennas are positioned so that side lobes are directed to each other, wherein the antennas are designed such that said side lobes are suppressed.

6. The system according to claim 3, wherein the receive and/or transmit antennas comprise an array of antenna elements and wherein said arrays are implemented with tapering that further reduces side lobe levels of the beams.

7. The system according to claim 6, wherein the tapering is carried out by monitoring traces of transmitted signals originated from said APs, and manipulating antennas weights to reduce said traces, and wherein said traces are fed into a cancellation process in which samples of the original signal are subtracted from said traces.

8. The system according to claim 1, wherein the directional beams use a first Wi-Fi frequency channel, said system further comprising an omni/sector antenna using a second Wi-Fi frequency channel whose power leakage to the first Wi-Fi frequency channel is lower than −

90 dBm, wherein gaps between the directional beams using said first Wi-Fi frequency channel, are filled by the omni/sector antenna using the second Wi-Fi frequency channel.

9. The system according to claim 1, wherein the one or more Wi-Fi receive antennas are implemented by one or more beamformers.

10. The system according to claim 1, further comprising a gateway and an access point coordinator configured to instruct the beamformers to spatially manipulate the beams, based on data received from the Wi-Fi UE devices, so as to maintain the sufficient isolation between the beams, over time.

11. The system according to claim 1, wherein at least some of the directional beams are served by a single AP.

12. The system according to claim 1, wherein a population of served UE devices is subdivided into two groups:

a first group in which the transmission of a UE device served by a given beam is received by one or more beams'"'"' receivers, and a second group in which UE devices'"'"' transmission is receivable exclusively by its serving beam.

13. The system according to claim 12, wherein the first group is allocated with one Wi-Fi channel and served by an omni/wide sector antenna, and wherein the second group is allocated with a second and a third Wi-Fi channel and is served by the directional beams.

14. The system according to claim 1, further comprising a coordinator which serves the plurality of APs, and configured to perform traffic analysis and to execute load sharing between beams by forcing UE devices handover based on load balancing requirements.

15. The system according to claim 14, wherein the forcing of the UE devices handover between beams is carried out via Extended Service Set (ESS), or via AP denial of service to a given UE device at a given beam.

16. The system according to claim 14, wherein crosstalk between co-channel directional beams is periodically estimated using UE devices estimation of alternative or neighboring N APs, and a relative power level of such neighbors versus the serving AP is reported by the UE to the AP, to be reported to the coordinator, generating for each UE crosstalk values originated by N−

1 co channel directional beams.

17. The system according to claim 16, wherein the coordinator initiates a handover of victim UE devices being affected by victimizing beams which cause crosstalk to said UE devices, to said victimizing beams.

18. The system according to claim 17, wherein the coordinator reports a crosstalk table indicating crosstalk between victimizing beams and victim UE devices to the victimizing beams and the victim UE devices and the APs feeding the victim UE and the victimizing beam perform time sharing when victim UEs are served.

19. The system according to claim 1 wherein said directional beams have a side lobe pattern of approximately −

30 dB, achieved via digital tapering, implemented by both mathematical calculation and closed loop cancellation using feedback from at least one of;

UE devices and calibration transmitters.

20. The system according to claim 1 wherein digital beamforming is performed by using an integrated Wi-Fi AP chip, converting all of the transmission RF paths into low frequency, digitizing, converting all of the receiving RF paths into low frequency and digitizing it, feeding said digital signals into a digital processing module which performs beamforming, tapering and cancellation, and then converting the outputs of the said digital processing module back to RF level and feeding the transmission and the receiving antenna arrays.

21. The system according to claim 1 where digital beamforming is performed by separating AP chip sets into two parts, one being the transceiver, the other being the baseband, lining up the baseband in groups and connecting the baseband to inputs of a digital processing module which performs beam forming, tapering, and cancellation, the transceiver in similar groups and connecting transceiver to the outputs of the said digital processing module, wherein the RF portion of the said transceivers are connected to a Transmission Antenna Array and a Receiving Antenna Array.

22. The system according to claim 1, wherein APs are configured to tune power level of the transmission and receiving sensitivity of receivers, to establish a range of coverage, so as to maximize the UE device population in an area covered by the serving AP receiver'"'"'s beam, but not covered by non-serving APs'"'"' receiving sidelobe beams.

23. The system according to claim 1, wherein the Wi-Fi transmit antennas beamformers are configured to produce and transmit a plurality of directional beams of at least first and second common frequencies having power leakage lower than −

90 dBm, wherein gaps between the directional beams using the first Wi-Fi frequency channel are filled by directional beams using the second Wi-Fi frequency channel.

24. A method comprising:

providing one or more Wi-Fi transmit beamformers, each comprising a plurality of transmit antennas;

providing one or more Wi-Fi receive antennas beamformers, each comprising a plurality of receive antennas;

providing a number N of co-located co-channel Wi-Fi access points (APs), connected to the Wi-Fi transmit beamformers and the Wi-Fi receive beamformers; and

producing a plurality of spatially directional beams of a common frequency, directed at a plurality of Wi-Fi user equipment (UE) such that the directional beams are sufficiently isolated from each other, so that at least some of the Wi-Fi UEs communicate simultaneously with the plurality of Wi-Fi access points,

wherein beam patterns of the transmit antennas exhibit contaminating transmit signals being an accumulated contribution of side lobes and back lobes, wherein the system further comprises amplitude/phase modules associated with said transmit antennas and null transmit module configured to receive a difference between signals received by said receive antenna and said contaminating transmit signals detected in the receiving circuitry and control said amplitude/phase modules so that transmit signal component in the receiver are reduced using accurate destructive interference manifested via closed loop.

25. The method according to claim 24, wherein the Wi-Fi AP protocol has a basic medium contention in which Wi-Fi devices packets are not synchronized or delayed and where a distributed coordination function is applied via at least one of:

carrier sense and random back-off, for collisions avoidance.

26. The method according to claim 24, wherein the N co-channel Wi-Fi transmitters are sufficiently isolated from N respective receivers such that the transmission power received by N−

1 of the N co-channel Wi-Fi transmitters is lower than a white Gaussian noise present in the N respective receivers.

27. The method according to claim 24, where a sample of transmitted signal of each beam, is used as a reference for an individual cancellation process for each antenna elements of the receiver systems, or for each beam of the receiver system.

28. The method according to claim 24, wherein APs are configured to have power level of the transmission, and receiving sensitivity of receivers, tuned to determine a range of cell'"'"'s coverage, in a way that sets up most of the UE devices population in an area that is covered by the serving AP receiver'"'"'s beam, but not covered by non-serving APs'"'"' receiving sidelobes beams.