Apparatus and method for joint power control in a wireless communication system

• US 20080171565A1
• Filed: 01/11/2008
• Published: 07/17/2008
• Est. Priority Date: 01/12/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lim, Eun-Taek, Park, Dong-Seek, Sivanesan, Kathiravetpillai, Shan, Cheng, Lee, Geun-Ho, Mazzarese, David
• Granted Patent: US 8,233,844 B2
• Time in Patent Office: Days
• US Class Current: 455/501
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 52/242 taking into account path loss
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

An apparatus and a method for joint power control in a wireless communication system are provided, in which customer premise equipments to be serviced are selected by scheduling, upon receipt of service requests from the customer premise equipments, the interference level of each of the selected customer premise equipments that affects an incumbent system is calculated, a total interference level affecting the incumbent system is calculated by summing the interference levels of the selected customer premise equipments, and a transmit power of the each customer premise equipment is reduced, if the total interference level is larger than a threshold.

Claims

1. A method for controlling power in a cognitive radio wireless communication system, the method comprising:

selecting customer premise equipments to be serviced by scheduling, upon receipt of service requests from the customer premise equipments;

calculating an interference level of each of the selected customer premise equipments that affects an incumbent system; and

calculating a total interference level affecting the incumbent system by summing the interference levels of the selected customer premise equipments.

2. The method of claim 1, wherein the interference level calculation comprises calculating the interference level of the customer premise equipment using a path loss according to a distance between the customer premise equipment and a protected contour of the incumbent system.

3. The method of claim 2, wherein the interference level calculation comprises calculating the interference level of the customer premise equipments using the following equation,

I(P_CPE,k,d_k,n)=P_CPE,k·

PL(d_k,n)

wherein d_k,n denotes a distance between a customer premise equipment k and the protected contour of the incumbent system, I(P_CPE,k,d_k,n) denotes an interference level induced by transmission of the customer premise equipment k, and PL(d_k,n) denotes a path loss from the customer premise equipment k to the protected contour of the incumbent system according to a channel model.

4. The method of claim 3, wherein the distance between the customer premise equipment and the protected contour of the incumbent system is calculated using at least one of Global Positioning System (GPS) information and statistical distance information.

5. The method of claim 1, wherein if the customer premise equipment is fixed, a distance between the customer premise equipment and the protected contour of the incumbent system is calculated using manually input location coordinates.

6. The method of claim 1, further comprising, if the total interference level is larger than a threshold, reducing a transmit power of the customer premise equipment at a predetermined ratio or by a predetermined decrement.

7. The method of claim 6, wherein the transmit power reduction comprises reducing the transmit power of the customer premise equipment using the following equation,

P_CPE,K^new=P_CPE,K(I−

Δ

_k%)

where Δ

k denotes a predetermined positive percentage constant for each customer premise equipment k (Δ

_k>

0), P_CPE,k denotes a second power of the customer premise equipment k before a joint power control, and P_CPE,k^new denotes a third power of the customer premise equipment k after the joint power control.

8. The method of claim 1, further comprising, if the total interference level is less than a threshold, allocating a transmit power satisfying the total interference level to each customer premise equipment.

9. The method of claim 1, wherein the interference level calculation comprises calculating the interference level of the customer premise equipment taking into account a second interference from an adjacent channel and plurality of interference levels of other customer premise equipments using the same channel.

10. The method of claim 1, wherein the cognitive radio wireless communication system comprises determines whether a specific channel or its adjacent channels are in use.

11. The method of claim 1, wherein the cognitive radio wireless communication system comprises determines whether there is at least one customer premise equipment using the same channel among the scheduled the customer premise equipments.

12. An apparatus for controlling power in a cognitive radio wireless communication system, the apparatus comprising:

a scheduler for selecting customer premise equipments to be serviced by scheduling, upon receipt of service requests from the customer premise equipments;

a path loss calculator for calculating an interference level for each of the selected customer premise equipments that affects an incumbent system, and calculating a total interference level that reaches a protected contour of the incumbent system using the interference levels of the selected customer premise equipments; and

a power controller for, if the total interference level is larger than a threshold, reducing a transmit power of the customer premise equipment.

13. The apparatus of claim 12, wherein the path loss calculator calculates the interference level of the customer premise equipment using a path loss according to a distance between the customer premise equipment and the protected contour of the incumbent system.

14. The apparatus of claim 12., wherein the path loss calculator calculates the interference level of the customer premise equipment, using the following equation,

I(P_CPE,k, d_k,n)=P_CPE,k·

PL(d_k,n)

wherein d_k,n denotes a distance between a customer premise equipment k and the protected contour of the incumbent system, I(P_CPE,k, d_k,n) denotes an interference level induced by a transmission of the customer premise equipment k, and PL(d_k,n) denotes a path loss from the customer premise equipment k to the protected contour of the incumbent system according to a channel model.

15. The apparatus of claim 14, wherein the distance between the customer premise equipment and the protected contour of the incumbent system is calculated using at least one of Global Positioning System (GPS) information and statistical distance information.

16. The apparatus of claim 12, wherein if the customer premise equipment is fixed, the distance between the customer premise equipment and the protected contour of the incumbent system is calculated using manually input location coordinates.

17. The apparatus of claim 12, wherein the power controller is configured to reduce the transmit power of the customer premise equipment at a predetermined ratio or by a predetermined decrement.

18. The apparatus of claim 17, wherein the power controller reduces the transmit power of the customer premise equipment using the following equation,

P_CPE,k^new=P_CPE,k(I−

Δ

_k%)

where Δ

_k denotes a predetermined positive percentage constant for the customer premise equipment k (Δ

_k>

0), P_CPE,k denotes a second power of the customer premise equipment k before a joint power control, and P_CPE,k denotes a third power of the customer premise equipment k after the joint power control.

19. The apparatus of claim 12, further comprising a controller for, if the total interference level is less than a threshold, allocating a second transmit power satisfying the total interference level to each of the customer premise equipmens.

20. The apparatus of claim 12, wherein the path loss calculator calculates the interference level of the customer premise equipment taking into account a second interference from an adjacent channel and a second plurality of interference levels of those customer premise equipments using the same channel.

22. The apparatus of claim 12, wherein further comprising a controller for determining whether there is at least one customer premise equipment using the same channel among the scheduled the customer premise equipments.

21. The apparatus of clam 12, wherein further comprising a controller for determining whether a specific channel or its adjacent channels are in use.

23. A method for controlling power in a cognitive radio wireless communication system, the method comprising:

calculating an interference level of each of base stations that affects an incumbent system;

calculating a total interference level affecting the incumbent system by summing the interference levels of the BSs; and

reducing a transmit power of the base station, if the total interference level is larger than a threshold.

24. The method of claim 23, wherein the interference level calculation comprises calculating the interference level of the base station using a path loss according to a distance between the base station and a protected contour of the incumbent system.

25. The method of claim 23, wherein the distance between the base station and the protected contour of the incumbent system is calculated using at least one of Global Positioning System (GPS) information and statistical distance information.

26. A method for controlling power in a cognitive radio wireless communication system, the method comprising:

acquiring an interference level of each of neighboring base stations adjacent to a first base station, the interference level affecting an incumbent system;

calculating a total interference level affecting the-incumbent system by summing the interference level of the first base station and interference levels of the neighboring base stations; and

reducing a transmit power of each of the first base station and the neighboring base stations, if the total interference level is larger than a threshold.

27. The method of claim 26, further comprising notifying the neighboring base stations of reduced transmit power values, after the power reduction.