Method for adaptively controlling other cell interference

• US 20080051096A1
• Filed: 08/22/2006
• Published: 02/28/2008
• Est. Priority Date: 08/22/2006
• Status: Active Grant

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Rao, Anil M.
• Granted Patent: US 7,873,327 B2
• Time in Patent Office: Days
• US Class Current: 455/449
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/247 where the output power of a terminal is based on a path parameter sent by another terminal

Abstract

Disclosed is a method of controlling a transmit power constraint at a mobile station using a pilot power ratio (PPR) or other measurement of relative received powers (or signal strengths) between a neighbor cell transmission and a serving cell transmission such that other-cell interference produced by the mobile station may be managed. The transmit power constraint may, for example, correspond to a total or per sub-carrier maximum allowable mobile station transmit power. The transmit power constraint may be decreased if an adjacent neighbor cell, or an adjacent neighbor cell with a strongest pilot signal strength at the mobile station, is interference overloaded, i.e., interference levels in the adjacent neighbor cell is above a threshold interference level. Such decrease may be based on a pilot power ratio between a received pilot power of the overloaded adjacent neighbor cell at the mobile station and a received pilot power of the serving cell at the mobile station. Conversely, the transmit power constraint may be decreased if at least one adjacent neighbor cell, or the adjacent neighbor cell with the strongest pilot signal strength at the mobile station, is not interference overloaded. Such increase may be based on a pilot power ratio between a received pilot power of the adjacent neighbor cell with the strongest pilot signal strength at the mobile station and a received pilot power of the serving cell at the mobile station.

Claims

1. A method of controlling transmit power in a wireless communication system comprising the steps of:

determining a transmit power constraint for a mobile station based on relative received powers of transmissions by a neighbor cell and a serving cell.

2. The method of claim 1, wherein the neighbor cell is an overloaded adjacent neighbor cell.

3. The method of claim 2, wherein the transmit power constraint is determined using a pilot power ratio corresponding to a ratio between a received pilot power of the overloaded adjacent neighbor cell at the mobile station and a received pilot power of the serving cell at the mobile station.

4. The method of claim 3, wherein the transmit power constraint is determined by increasing a previous transmit power constraint an amount based on the pilot power ratio.

5. The method of claim 2, wherein the overloaded adjacent neighbor cell is an adjacent neighbor cell with a strongest pilot signal strength at the mobile station among all adjacent neighbor cells which are interference overloaded.

6. The method of claim 1, wherein the neighbor cell is an adjacent neighbor cell with a strongest pilot signal strength at the mobile station.

7. The method of claim 6, wherein the transmit power constraint is determined using a pilot power ratio corresponding to a ratio between a received pilot power of the adjacent neighbor cell with the strongest pilot signal strength at the mobile station and a received pilot power of the serving cell at the mobile station.

8. The method of claim 7, wherein the transmit power constraint is determined by decreasing a previous transmit power constraint an amount based on the pilot power ratio.

9. The method of claim 1, wherein the transmit power constraint is determined at a base station associated with the serving cell and transmitted to the mobile station.

10. The method of claim 1, wherein the transmit power constraint is determined at the mobile station and transmitted to a base station associated with the serving cell.

11. The method of claim 1, wherein the transmit power constraint corresponds to a maximum transmit power spectral density constraint indicating a maximum allowable transmit power per sub-carrier frequency.

12. A method of controlling transmit power in a wireless communication system comprising the steps of:

receiving overload information from a plurality of adjacent neighbor cells; and

determining a transmit power constraint for a mobile station based on relative received powers of transmissions by a neighbor cell and a serving cell if a condition associated with the overload information is met.

13. The method of claim 12, wherein the condition is met if the overload information indicates that an adjacent neighbor cell with a strongest pilot signal strength at the mobile station is interference overloaded, and the transmit power constraint is determined by decreasing a previous transmit power constraint using relative received powers of transmissions by the adjacent neighbor cell that is interference overloaded and the serving cell.

14. The method of claim 12, wherein the condition is met if the overload information indicates that at least one adjacent neighbor cell is interference overloaded, and the transmit power constraint is determined by decreasing a previous transmit power constraint using relative received powers of transmissions by the at least one adjacent neighbor cell that is interference overloaded and the serving cell.

15. The method of claim 12, wherein the condition is met if the overload information indicates that no adjacent neighbor cell is interference overloaded, and the transmit power constraint is determined by increasing a previous transmit power constraint using relative received powers of transmissions by an adjacent neighbor cell and the serving cell.

16. The method of claim 12, wherein the condition is met if the overload information indicates that an adjacent neighbor cell with a strongest pilot signal strength at the mobile station is not interference overloaded, and the transmit power constraint is determined by increasing a previous transmit power constraint using relative received powers of transmissions by the adjacent neighbor cell with the strongest pilot signal strength and the serving cell.

17. The method of claim 12, wherein the overload information is received at a base station associated with the serving cell, and the transmit power constraint is determined at the base station.

18. The method of claim 12, wherein the overload information is received at the mobile station, and the transmit power constraint is determined at the mobile station.

19. The method of claim 12 comprising the additional step of:

transmitting the determined transmit power constraint if the condition is met.

20. The method of claim 12, wherein the step of determining the transmit power constraint includes increasing or decreasing a previous transmit power constraint using a pilot power ratio corresponding to a ratio between a received pilot power of an adjacent neighbor cell at the mobile station and a received pilot power of the serving cell at the mobile station.