Method and apparatus for directional radio communication

• US 6,393,303 B1
• Filed: 09/17/1999
• Issued: 05/21/2002
• Est. Priority Date: 02/13/1997
• Status: Expired due to Term

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Katz, Marcos
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): Vuong, Quochien B.
• Application Number:
  US09/367,240
• Time in Patent Office: 977 Days
• Field of Search: 455/561, 455/562, 455/63, 455/67.1, 455/67.3, 455/73, 455/269, 455/277.1, 455/277.2, 342/359, 342/360, 342/368, 342/383, 370/334, 370/342, 370/347
• US Class Current: 455/562.1
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

A method of directional radio communication between a first station and a second station comprises the following steps. A first signal transmitted from the second station is received at the first station. The first signal is receivable from a plurality of different directions. A principle beam direction from which the first signal is received by the first station is determined. A plurality of beam directions for transmitting a radiation beam is defined at the first station. Each of the beam directions is selectable. The determined principle beam direction and at least one other auxiliary beam direction is selected at the first station. The at least one auxiliary beam direction is adjacent to the determined principle beam direction. A second signal is transmitted from the first station to the second station in the selected beam direction.

Claims

1. A method of directional radio communication between a first station and a second station, said method comprising the steps of:

receiving at said first station a first signal transmitted from said second station, said first signal being receivable from a plurality of different directions;

determining a principal beam direction from which said first signal is received by said first station;

defining at the first station a plurality of beam directions for transmitting a radiation beam, wherein each of said beam directions is selectable; and

selecting at said first station said determined principal beam direction and at least one other auxiliary beam direction, said at least one auxiliary beam direction being adjacent to said determined principal beam direction and transmitting a second signal from said first station to said second station in said selected beam directions, wherein the transmission power in each of said beam directions is individually determinable and wherein the strength of the second signal transmitted in said at least one auxiliary direction is less than or equal to the strength of the second signal transmitted in said determined principal direction, and wherein the ratio of the strength of the second signal transmitted in said at least one auxiliary direction to the strength of the second signal transmitted in said determined principal direction is proportional to the ratio of the strength of the first signal received by said first station from said at least one auxiliary direction to the strength of the first signal received by the first station in said determined principal direction.

2. A method as claimed in claim 1, wherein said two ratios are substantially equal.

3. A method as claimed in claim 1, wherein the strength of said signal transmitted in said at least one auxiliary beam direction is determined in dependence on a parameter of the first signal received in said at least one auxiliary direction.

4. A method as claimed in claim 1, wherein at least one auxiliary direction comprises the beam directions on either side of the determined principal direction.

5. A method as claimed in claim 1, wherein the direction from which the strongest version of the first signal is received is determined to be said principal direction.

6. A method as claimed in claim 1, wherein the direction from which a version of first signal is first received is determined to be the principal direction.

7. A method as claimed in claim 1, wherein if the strength of the first signal received in said at least one other auxiliary direction is very much smaller than the strength of the first signal received in the determined principal direction, then said second signal transmitted from said first station to said second station is only transmitted in said determined principal direction.

8. A method as claimed in claim 1, wherein if the strength of the first signal received in said determined principal direction and in said at least one auxiliary direction are substantially the same, then the first station is arranged to transmit the second signal in said determined principal direction and in at least one other auxiliary direction at substantially the same signal strength.

9. A method as claimed in claim 1, wherein the strength of the second signal transmitted by the first station in at least one of said determined principal directions and the at least one auxiliary direction is dependent on the strength of the first signal received by said first station in the corresponding direction.

10. A method as claimed in claim 1, wherein the strength of the second signal in at least one of said determined principal directions and at least one auxiliary direction is dependent on the average strength of a plurality of preceding signals received by said first station from said second station in the corresponding direction.

11. A method as claimed in claim 1, including the step of determining if the distance between the second station and the first station is below a predetermined value, and if so then the second signal transmitted from said first station to said second station is transmitted with a relatively wide angular spread.

12. A method as claimed in claim 1, wherein said first station is a base transceiver station in a cellular network system.

13. A method as claimed in claim 1, wherein said second station is a mobile station.

14. A first station for directional radio communication with a second mobile station, said first station comprising:

receiver for receiving a first signal transmitted by said second station, said first signal being receivable from a plurality of different directions;

circuitry for determining the principal direction from which said first signal is received;

a transmitter for transmitting a second signal from the first station to the second station, said transmitter being arranged to transmit a radiation beam in a plurality of beam directions, wherein each of said beam directions is selectable; and

a controller for controlling said transmitter, wherein said controller is arranged to control the transmitter to transmit said second signal to said second station in the determined principal beam direction, said at least one auxiliary direction being adjacent to the determined principal direction, wherein the transmission power in each of said beam directions is individually determinable and wherein the strength of the second signal transmitted in said at least one auxiliary direction is less than or equal to the strength of the second signal transmitted in said determined principal direction, wherein the ratio of the strength of the second signal transmitted in said at least one auxiliary direction to the strength of the second signal transmitted in said determined principal direction is proportional to the ratio of the strength of the first signal received by said first station from said at least one auxiliary direction to the strength of the first signal received by the first station in said determined principal direction.

15. A first station as claimed in claim 14, wherein said receiver and said transmitter comprise an antenna array which is arranged to provide a plurality of signal beams in a plurality of different directions.

16. A first station as claimed in claim 14, wherein the controller is arranged to select the strength of said second signal in said auxiliary direction in dependence on a parameter of the first signal received in said at least one auxiliary direction.

17. A first station as claimed in claim 15, wherein the controller is arranged to select the strength of said second signal in said auxiliary direction in dependence on a parameter of the first signal received in said at least one auxiliary direction.