Vertical adaptive antenna array for a discrete multitone spread spectrum communications system

• US 6,782,039 B2
• Filed: 05/08/2003
• Issued: 08/24/2004
• Est. Priority Date: 02/24/1997
• Status: Expired due to Term

• Current Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Original Assignee: AT&T Wireless Services Incorporated (AT&T, Inc.)
• Inventors: Becker, Joel E., Stolarz, Douglas Frank, Alamouti, Siavash
• Primary Examiner(s): Ghebretinsae, Temesghen
• Application Number:
  US10/435,304
• Publication Number:
  US 20030231700A1
• Time in Patent Office: 474 Days
• Field of Search: 375/130, 375/147, 375/150, 375/349, 455/562
• US Class Current: 375/147
• 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: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04J 13/16 Code allocation
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 5/026 using code division

Abstract

Two or more antenna elements are arranged in the vertical direction to give vertical spatial adaptivity to a wireless discrete multitone spread spectrum communications system. The system is based on a combination of Discrete Multitone Spread Spectrum (DMT-SS) and multi-element adaptive antenna array technologies. This enables the automatic positioning of a beam in the vertical direction to position nulls where interferers are located on the same azimuth but are separated in elevation.

Claims

1. A communication method, comprising:

receiving at a station a spread signal, wherein the station has a multi-element antenna array with a first set of elements arranged in a spaced vertical direction and a second set of elements arranged in a spaced horizontal direction, and wherein the spread signal is a data signal spread over multiple discrete tones according to a remote spreading code of a remote station;

adaptively despreading the received signal by using a first despreading code based on characteristics of the received signal at the first set of elements of the array, wherein a vertical displacement of the first set of elements enables the station to perform vertical beam steering; and

adaptively despreading the signal received by using a second despreading code based on characteristics of the received signal at the second set of elements of the array, wherein a horizontal displacement of the second set of elements enables the station to perform horizontal beam steering.

2. The communications method of claim 1, further comprising:

spreading a second data signal with a second spreading code derived from the first despreading code to distribute the second data signal over multiple discrete tones, and forming a first spectrally spread signal that is spatially spread vertically to perform vertical transmit beam steering; and

spreading the second data signal with a second spreading code derived from the second despreading code to distribute the second data signal over multiple discrete tones, and forming a second spectrally spread signal that is spatially spread horizontally to perform horizontal transmit beam steering.

3. The communications method of claim 2, wherein the spreading includes multiplying a complex number representation of multiple second spreading codes by a complex number representation of the data signal to be transmitted.

4. The communications method of claim 2, wherein the spreading includes adaptively positioning transmitted signal energy of the spread signals towards a source of the received spread signal and adaptively diminishes transmitted signal energy towards interferers.

5. The communications method of claim 1, wherein the spread signals have a spectral form of a discrete multitone signal transmitted on multiple elements in the array.

6. The communications method of claim 1, wherein the despreading includes multiplying a complex number representation of multiple despreading codes by a complex number representation of the received spread signal.

7. The communications method of claim 1, wherein the despreading includes determining values of complex despreading codes which are then multiplied with a complex number representation of the received signals, resulting in an estimate of the first data signal.

8. The communications method of claim 1, wherein the despreading includes adaptively adjusting spatial direction of receive sensitivity towards a desired signal source and diminishing receive sensitivity from interfering sources.

9. The communications method of claim 1, wherein the antenna array has a planar symmetry.

10. The communications method of claim 1, wherein the antenna array has a cylindrical symmetry.

11. A communications system comprising:

a station having a multi-element antenna array with a first set of antenna elements arranged in a spaced vertical direction and a second set of antenna elements arranged in a spaced horizontal direction;

a receiver at the station for receiving a spread signal, the spread signal being a data signal spread over multiple discrete tones in accordance with a remote spreading code assigned to a remote station;

despreading circuitry configured to adaptively despread the received signal by way of a first despreading code that are based on characteristics of the received signals at the first set of elements of the array, wherein a vertical displacement of the first set of elements is configured to perform vertical receive beam steering; and

wherein the despreading circuitry is further configured to adaptively despread the signal received by using a second despreading code based on characteristics of the received signals at the second set of elements of the array, wherein a horizontal displacement of the second set of elements is configured to perform horizontal receive beam steering.

12. The communications system of claim 11, further comprising:

spreading circuitry configured to spread a second data signal with first spreading codes derived from the first despreading code to distribute the second data signal over multiple discrete tones and the first set of elements of the array, and form a first spectrally spread signal that is spatially spread vertically to perform vertical transmit beam steering; and

wherein the spreading circuitry is further configured to spread the second data signal with second spreading codes derived from the second despreading code to distribute the second data signal over the multiple discrete tones and the second set of elements of the array, and form a second spectrally spread signal that is spatially spread horizontally to perform horizontal transmit beam steering.

13. The communications system of claim 12, wherein the receiver is configured to multiply a complex number representation of the second spreading codes by a complex number representation of the data signal to be transmitted.

14. The communications system of claim 12, wherein the station is configured to adaptively position transmitted signal energy of the spread signals towards a source of the received spread signal and adaptively diminish transmitted signal energy towards interferers.

15. The communications system of claim 11, wherein the spread signals have a spectral form of a discrete multitone signal transmitted on elements in the array.

16. The communications system of claim 11, wherein the despreading is a multiplication of a complex number representation of the despreading codes times a complex number representation of the received spread signal.

17. The communications system of claim 11, wherein the despreading circuitry is further configured to determine values of complex despreading codes which are then multiplied with a complex number representation of the received signals, resulting in an estimate of the data signal.

18. The communications system of claim 11, wherein the despreading circuitry is further configured to adaptively position the spatial direction of receive sensitivity towards a desired signal source and diminish receive sensitivity from interfering sources.

19. The communications system of claim 11, wherein the antenna array has a planar symmetry.

20. The communications system of claim 11, wherein the antenna array has a cylindrical symmetry.