Method for a Canceling Self Interference Signal Using Active Noise Cancellation in the Air for Full Duplex Simultaneous (In Time) and Overlapping (In Space) Wireless Transmission & Reception on the Same Frequency band

• US 20120155335A1
• Filed: 12/13/2011
• Published: 06/21/2012
• Est. Priority Date: 12/13/2010
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Laboratories America Inc (NEC Corporation)
• Inventors: Khojastepour, Mohammad A., Sundaresan, Karthikeyan, Rangarajan, Sampath
• Granted Patent: US 8,879,433 B2
• Time in Patent Office: Days
• US Class Current: 370/278
• CPC Class Codes: H01Q 21/00 Antenna arrays or systems arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system H01Q3/00
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

A method for full duplex communication includes creating a canceling self interference signal using active noise cancelation in the air by using a plurality of transmit antennas and feeding the plurality of antennas with an RF signal in so that part of said RF signal is destructively combined at a receive antenna, and attaining full-duplex simultaneous in time and overlapping in space wireless transmission and reception on same frequency band responsive to the step of creating a canceling self interference signal.

Claims

1. A method for full duplex communication comprising the steps of:

creating a canceling self interference signal using active noise cancelation in the air by using a plurality of transmit antennas and feeding the plurality of antennas with an RF signal in so that part of said RF signal is destructively combined at a receive antenna; and

attaining full-duplex simultaneous in time and overlapping in space wireless transmission and reception on same frequency band responsive to the step of creating a canceling self interference signal.

2. The method of claim 1, wherein the transmit antennas are grouped into two sets:

a first group (driving transmit antennas) from which the signal of interest is transmitted and a tandem group that generates destructive interference at a receive antenna based on the signal of the first group of antennas and the channel between the transmit and receive antennas.

3. The method of claim 2, wherein the antennas are omni-directional antennas.

4. The method of claim 3, wherein the base of the driving transmit antennas are placed in a straight line and the same number of tandem antennas are placed in the same line such that each pair of driving antenna and its tandem antenna are in symmetric position with respect to the base of a receive antenna.

5. The method of claim 4, wherein the RF signal transmitted though a transmit antenna and its tandem transmit antenna are 180 degrees phase shifted.

6. The method of claim 2, wherein the distance between a transmit antenna and its tandem antenna is integer multiple of λ

(λ

is the wavelength of the carrier frequency) plus λ

/2.

7. The method of claim 6, wherein the RF signal transmitted though a transmit antenna and its tandem transmit antenna have zero phase shift.

8. The method of claim 6, wherein a received antennas is placed on the line passing through a transmit antennas and its tandem transmit antenna outside the line segment between the transmit antenna and its tandem antenna.

9. The method of claim 6, wherein a received antennas is placed on the line passing through a transmit antennas and its tandem transmit antenna inside the line segment between the transmit antenna and its tandem antenna at a position that its distances from these points is an integer multiple of λ

.

10. The method of claim 1, wherein the antennas are directional antenna.

11. The method of claim 2, wherein each antenna and its tandem antenna have the same RF characteristics such as antenna pattern and insertion loss.

12. The method of claim 1 wherein polarized antennas are used. (we can further restrict this claim later by adding some phrase similar to this:

“

such that the each (transmit or receive) antenna and its tandem antenna have the same RF characteristics.

13. The method of claim 12, wherein the same polarization is used for transmit antennas.

14. The method of claim 12, wherein the same polarization is used for receive antennas

15. The method of claim 14, wherein the polarization of the transmit antennas are orthogonal to the polarization of the receive antennas

16. The method of claim 5, wherein a BALUN is used to split the transmit signal and generate two signals that are 180 degrees out of phase.

17. The method of claim 10, wherein the antennas are directional wherein such that the each transmit or receive antenna and its tandem antenna have the same RF characteristics.

18. The method of claim 1, wherein placing an antenna on a straight line comprising placing a base on the antenna in a straight line and positioning the antennas in the same direction in the air vertical, horizontal or with the same degree.