System and method for side lobe suppression using controlled signal cancellation

• US 8,929,322 B1
• Filed: 11/20/2013
• Issued: 01/06/2015
• Est. Priority Date: 11/20/2013
• Status: Expired due to Fees

• Current Assignee: Magnolia Broadband Incorporated
• Original Assignee: Magnolia Broadband Incorporated
• Inventors: Kludt, Kenneth, Harel, Haim
• Primary Examiner(s): Jaroenchonwanit, Bunjob
• Application Number:
  US14/085,352
• Time in Patent Office: 412 Days
• Field of Search: None
• US Class Current: 370/329
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 3/2617 Array of identical elements
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 72/27 between access points
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

A system and method for selective suppression of sidelobe signals using controlled signal cancellation. An indication may be received from a single user equipment (UE) at each of two or more access points (APs) over the same channel. A relatively stronger power signal is received over a primary lobe of a communication beam of one of the APs and the relatively weaker power signal is received over a side lobe of a communication beam of another one of the APs. The efficacy of signal cancellation may be tested by turning signal cancellation on and off to measure the UE signals received at one of the APs. If interference is lower when signal cancellation is turned on, signal cancellation may be applied for continued communication with said UE to cancel side lobe signals and if interference is lower when signal cancellation is turned off, no signal cancellation may be applied.

Claims

1. A method for selective suppression of sidelobe signals using controlled signal cancellation, the method comprising:

receiving an indication that a signal from a single user equipment (UE) is received at each of two or more access points (APs) over the same channel, wherein the relatively stronger power signal is received over a primary lobe of a communication beam of one of the APs and the relatively weaker power signal is received over a side lobe of a communication beam of another one of the APs;

testing the efficacy of signal cancellation by turning signal cancellation on and off to measure the UE signals received at one of the APs; and

if interference is lower when signal cancellation is turned on, applying said signal cancellation for continued communication with said UE to cancel side lobe signals and

if interference is lower when signal cancellation is turned off, communicating with said UE without applying said signal cancellation.

2. The method of claim 1 further comprising detecting the signal modulation of the UE'"'"'s signal and applying continuous signal cancellation to the UE if the modulation requires a below threshold maximum interference level and applying said selective cancellation of sidelobe signals if the modulation allows an above threshold maximum interference level.

3. The method of claim 1, wherein applying said signal cancellation during receiving includes applying coupling coefficients h_ij as a function of the received signal over each beam i to the received signal over each beam j.

4. The method of claim 3, wherein applying said signal cancellation during transmitting includes applying coupling coefficients h_ji when transmitting over both beams i and j.

5. The method of claim 1 comprising applying the coupling coefficients h_ji for signal cancellation coincident with the transmission.

6. The method of claim 1 comprising providing an additional channel of coverage by an additional AP using an antenna that covers an entire sector serviced by the two or more APs.

7. The method of claim 6, further comprising determining whether a greater than threshold amount of interference is experienced when signal cancellation is both on and off, and if so, then assigning the UE to communicate with the additional AP over the additional channel.

8. The method of claim 1, wherein adjacent APs communicate over different channels to provide continuous coverage to UEs at boundaries between beams of different APs.

9. The method of claim 1, wherein the primary lobe of each beam is oriented in a direction of a main axis of symmetry of the beam and the sidelobe of each beam is oriented in a direction askew from the main axis of symmetry of the beam.

10. The method of claim 1 comprising tapering signals by individually applying weights to signals transmitted/received to/from each of a plurality of antennas.

11. A method for selective suppression of sidelobe signals using controlled signal cancellation, the method comprising:

transmitting/receiving signals to/from a plurality of access points (APs) along the direction of a plurality of (N) different respective beams, wherein each of the plurality of (N) beams includes a primary lobe providing relatively high signal power surrounded by two or more side lobes providing relatively low signal power, wherein a primary lobe of one beam is substantially separated from a primary lobe of another beam communicating over the same channel but at least partially overlapping one or more side lobes of the beam,

determining if user equipment (UE) detected by two or more APs is communicating using a side lobe signal or a primary lobe signal, and

applying signal cancellation to suppress the sidelobe signals if the UE is determined to communicate using a sidelobe signal but not applying signal cancellation if the UE is determined to communicate using a primary lobe signal.

12. The method of claim 11 further comprising detecting the signal modulation of the UE and applying continuous signal cancellation to the UE regardless of said determination if the modulation requires a below threshold maximum interference level and applying said selective cancellation of sidelobe signals contingent upon said determination if the modulation allows an above threshold maximum interference level.

13. A system for selective suppression of sidelobe signals using controlled signal cancellation, the system comprising:

a processor configured to;

receive an indication that a signal from a single user equipment (UE) is received at each of two or more access points (APs) over the same channel, wherein the relatively stronger power signal is received over a primary lobe of a communication beam of one of the APs and the relatively weaker power signal is received over a side lobe of a communication beam of another one of the APs;

test the efficacy of signal cancellation by turning signal cancellation on and off to measure the UE signals received at one of the APs; and

if interference is lower when signal cancellation is turned on, apply said signal cancellation for continued communication with said UE to cancel side lobe signals and

if interference is lower when signal cancellation is turned off, communicate with said UE without applying said signal cancellation.

14. The method of claim 13, wherein the processor is further configured to detect the signal modulation of the UE'"'"'s signal and apply continuous signal cancellation to the UE if the modulation requires a below threshold maximum interference level and apply said selective cancellation of sidelobe signals if the modulation allows an above threshold maximum interference level.

15. The system of claim 13, wherein the processor is further configured to apply said signal cancellation during receive intervals by applying coupling coefficients h_ij as a function of the received signal over each beam i to the received signal over each beam j.

16. The system of claim 15, wherein the processor is further configured to apply said signal cancellation during transmit intervals by applying coupling coefficients h_ji when transmitting over both beams i and j.

17. The system of claim 13, wherein the processor is further configured to apply the coupling coefficients h_ji for signal cancellation coincident with the transmission.

18. The system of claim 13, wherein the processor is further configured to provide an additional channel of coverage by an additional AP using an antenna that covers an entire sector serviced by the two or more APs.

19. The system of claim 18, wherein the processor is further configured to assign the UE to communicate with the additional AP over the additional channel if a greater than threshold amount of interference is experienced when signal cancellation is both on and off.

20. The system of claim 13, wherein adjacent APs communicate over different channels to provide continuous coverage to UEs at boundaries between beams of different APs.

21. The system of claim 13, wherein the primary lobe of each beam is oriented in a direction of a main axis of symmetry of the beam and the sidelobe of each beam is oriented in a direction askew from the main axis of symmetry of the beam.

22. The system of claim 13, wherein the processor is further configured to taper signal amplitudes by individually applying weights to signals transmitted/received to/from each of a plurality of antennas.

23. A system for selective suppression of sidelobe signals using controlled signal cancellation, the system comprising:

a processor configured to control an antenna array to;

transmitting/receiving signals to/from a plurality of access points (APs) along the direction of a plurality of (N) different respective beams, wherein each of the plurality of (N) beams includes a primary lobe providing relatively high signal power surrounded by two or more side lobes providing relatively low signal power, wherein a primary lobe of one beam is substantially separated from a primary lobe of an adjacent beam communicating over the same channel but at least partially overlapping one or more side lobes of the adjacent beam,

determine if user equipment (UE) detected by two or more APs is communicating using a side lobe signal or a primary lobe signal, and

apply signal cancellation to suppress the sidelobe signals if the UE is determined to communicate using a sidelobe signal but not apply signal cancellation if the UE is determined to communicate using a primary lobe signal.

24. The system of claim 23, wherein the processor is further configured to detect the signal modulation of the UE and apply continuous signal cancellation to the UE regardless of said determination if the modulation requires a below threshold maximum interference level and the processor is adapted to apply said selective cancellation of sidelobe signals contingent upon said determination if the modulation allows an above threshold maximum interference level.