TRANSMIT POWER CONTROL TECHNIQUES FOR WIRELESS COMMUNICATION SYSTEMS

• US 20090047916A1
• Filed: 10/13/2005
• Published: 02/19/2009
• Est. Priority Date: 10/13/2004
• Status: Active Grant

• Current Assignee: Mcmaster University
• Original Assignee: Mcmaster University
• Inventors: Haykin, Simon
• Granted Patent: US 8,060,035 B2
• Time in Patent Office: Days
• US Class Current: 455/115.100
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels
• CPC Class Codes: H04W 52/265 taking into account the quality of service QoS

Abstract

Methods and systems of controlling transmit power in a multi-user wireless communication system is provided, A transmit power, level for a transmitter is determined according to an algorithm based in communication theory, such as an iterative water-filling procedure, which takes into account an assumption of transmit behaviours of transmitters in the communication system, Actual transmit behaviours of transmitters in the communication system are monitored using a learning algorithm to determine whether any transmitters exhibit transmit behaviours which are not consistent with the assumption.

Claims

1. A method of controlling transmit power in a multi-user wireless communication system, comprising:

determining a transmit power level for a transmitter in the wireless communication system according to a communication theory algorithm, the communication theory algorithm being based on an assumption of behaviours of transmitters in the communication system; and

monitoring behaviours of the transmitters in the communication system using a learning algorithm.

2. The method of claim 1, wherein the communication theory algorithm comprises an iterative water-filling procedure, the iterative water-filling procedure accounting for determined transmit power levels of the transmitter and other transmitters in the communication system.

3. The method of claim 2, wherein the iterative water-filling procedure comprises:

initializing a transmit power distribution across n transmitters;

performing water-filling for the transmitter to determine a transmit power level for a target data transmission rate of the transmitter subject to a power constraint for the transmitter and a level of interference, the level of interference comprising a noise floor plus either initialized transmit power levels or previously determined transmit power levels for the other transmitters;

determining whether a data transmission rate of the transmitter is greater than or less than a target data transmission rate of the transmitter, and if so, adjusting the determined transmit power level for the transmitter;

determining whether a target data transmission rate of at least one of the n transmitters is not satisfied by a respective adjusted transmit power level for the at least one transmitter, and repeating the operation of performing water-filling where the target data transmission rate of at least one of the n transmitters is not satisfied.

4. The method of claim 3, wherein the operations of performing, determining whether a data transmission rate of a transmitter is greater than or less than a target transmission rate, and adjusting are repeated for each of the other transmitters, wherein determining whether the target data transmission rate of at least one of the n transmitters is not satisfied comprises determining whether the target data transmission rates of all of the 1′

transmitters are not satisfied, and wherein repeating the operation of performing water-filling comprises repeating the operation of performing water-filling where the target data transmission rates of all of the ii transmitters are not satisfied.

6. The method of claim 3, wherein adjusting comprises reducing the determined transmit power level for the transmitter where the data transmission rate of the transmitter is greater than the target data transmission rate of the transmitter, and wherein, where the data transmission rate of the transmitter is less than the target data transmission rate of the transmitter, adjusting comprises:

determining whether increasing the determined transmit power level of the transmitter would violate an interference level limit; and

increasing the determined transmit power level of the transmitter where increasing the determined transmit power level of the transmitter would not violate an interference level limit.

10. The method of claims 1, wherein monitoring comprises determining whether the behaviours of the transmitters are consistent with the assumption of behaviours, and wherein the method further comprises:

generating an alert where the behaviour of one or more of the transmitters is not consistent with the assumption.

12. The method of claim 1, further comprising:

detecting at least one spectrum hole,

wherein determining comprises determining a transmit power level for the transmitter for transmission within the at least one spectrum hole.

13. The method of claim 12, further comprising:

predicting subsequent availability of the at least one spectrum hole; and

repeating the operations of determining and monitoring when the at least one spectrum hole is predicted to become unavailable.

14. The method of claim 12, further comprising:

detecting a further spectrum hole;

detecting an increase in interference in the at least one spectrum hole; and

repeating the operations of determining and monitoring to control transmit power levels for the transmitter for transmission within the further spectrum hole responsive to detecting an increase in interference in the at least one spectrum hole.

15. The method of claim 1, further comprising:

determining a position of the transmitter relative to other transmitters in the communication system; and

determining a multi-user path loss matrix of the operating environment of the transmitter based on the determined position of the transmitter relative to the other transmitters.

17. The method of claim 1, wherein the learning algorithm comprises a regret-conscious learning algorithm or a Lagrangian learning algorithm.

19. The method of claim 6, further comprising:

adapting a modulation strategy for transmission of data by the transmitter where the data transmission rate of the transmitter is less than the target data transmission rate of the transmitter and increasing the determined transmit power level of the transmitter would violate an interference level limit.

20. The method of claim 6, wherein determining whether increasing the determined transmit power level of the transmitter would violate an interference level limit comprises determining whether increasing the determined transmit power level of the transmitter would violate an interference level limit within a spectrum hole, the method further comprising, where the data transmission rate of the transmitter is less than the target data transmission rate of the transmitter and increasing the determined transmit power level of the transmitter would violate an interference level limit within the spectrum hole:

detecting a further spectrum hole; and

determining a further transmit power level for the transmitter for transmission within the new spectrum hole.

21. A machine-readable medium storing instructions which when executed perform the method of claim 1.

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22. A system for controlling transmit power in a multi-user wireless communication system, comprising:

an input for receiving information associated with transmit behaviours of transmitters in the wireless communication system; and

a processor operatively coupled to the input and configured to determine a transmit power level for a transmitter in the wireless communication system according to a communication theory algorithm, the communication theory algorithm being based on an assumption of transmit behaviours of transmitters in the communication system, and to monitor the transmit behaviours of the transmitters in the communication system using a learning algorithm.

23. The system of claim 22, wherein the processor is further configured to implement a cognitive radio.

24. The system of claim 22, wherein the communication theory algorithm comprises an iterative water-filling procedure, the iterative water-filling procedure accounting for determined transmit power levels of the transmitter and other transmitters in the communication system.

25. The system of claim 22, wherein the processor is configured to determine a transmit power level for the transmitter by:

initializing a transmit power distribution across n transmitters;

performing water-filling for the transmitter to determine a transmit power level for a target data transmission rate of the transmitter subject to a power constraint for the transmitter and a level of interference, the level of interference comprising a noise floor plus either initialized transmit power levels or previously determined transmit power levels for the other transmitters;

determining whether a data transmission rate of the transmitter is greater than or less than a target data transmission rate of the transmitter, and if so, adjusting the determined transmit power level for the transmitter;

determining whether a target data transmission rate of at least one of the n transmitters is not satisfied by a respective adjusted transmit power level for the at least one transmitter, and repeating the operation of performing water-filling where the target data transmission rate of at least one of the n transmitters is not satisfied.

26. The system of claim 25, wherein the processor is further configured to determine whether the target data transmission rate of at least one of the n transmitters is not satisfied by determining whether the target data transmission rates of all of the n transmitters are not satisfied, and to repeat the operation of performing water-filling where the target data transmission rates of all of the n transmitters are not satisfied.

27. The system of claim 25, wherein the processor is configured to adjust the determined transmit power level by reducing the determined transmit power level for the transmitter where the data transmission rate of the transmitter is greater than the target data transmission rate of the transmitter, and is further configured to adjust the determined transmit power level by:

determining whether increasing the determined transmit power level of the transmitter would violate an interference level limit, where the data transmission rate of the transmitter is less than the target data transmission rate of the transmitter; and

increasing the determined transmit power level of the transmitter where increasing the determined transmit power level of the transmitter would not violate an interference level limit.

31. The system of claim 22, wherein the processor is configured to monitor the transmit behaviours of the transmitters by determining whether the behaviours of the transmitters are consistent with the assumption of behaviours, and wherein the processor is further configured to generate an alert where the behaviour of one or more of the transmitters is not consistent with the assumption.

32. The system of claim 22, wherein the processor is further configured to detect at least one spectrum hole, and to determine a transmit power level by determining a transmit power level for the transmitter for transmission within the at least one spectrum hole.

33. The system of claim 32, wherein the at least one spectrum hole comprises a plurality of spectrum holes, and wherein the processor is configured to determine a transmit power level by determining a set of transmit power levels comprising multiple transmit power levels for transmission within respective ones of the plurality of spectrum holes.

34. The system of claim 32, wherein the processor is further configured to predict subsequent availability of the at least one spectrum hole, and to repeat the operations of determining and adapting when the at least one spectrum hole is predicted to become unavailable.

35. The system of claim 32, wherein the processor is further configured to detect a further spectrum hole, to detect an increase in interference in the at least one spectrum hole, and to repeat the operations of determining and adapting to control transmit power levels for the transmitter for transmission within the further spectrum hole responsive to detecting an increase in interference in the at least one spectrum hole.

36. The system of claim 22, wherein the processor is further configured to determine a position of the transmitter relative to the other users, and to determine a multi-user path loss matrix of the operating environment of the transmitter based on the determined position of the transmitter relative to the other transmitters.

39. The system of claim 22, wherein the learning algorithm comprises a regret-conscious learning algorithm or a Lagrangian learning algorithm.

41. The system of claim 27, wherein the processor is further configured to adapt a modulation strategy for transmission of data by the transmitter where the data transmission rate of the transmitter is less than the target data transmission rate of the transmitter and increasing the determined transmit power level of the transmitter would violate an interference level limit.

42. The system of claim 27, wherein the processor is configured to determine whether increasing the determined transmit power level of the transmitter would violate an interference level limit by determining whether increasing the determined transmit power level of the transmitter would violate an interference level limit within a spectrum hole, and wherein the processor is further configured to detect a further spectrum hole and to determine a further transmit power level for the transmitter for transmission within the further spectrum hole, where the data transmission rate of the transmitter is less than the target data transmission rate of the transmitter and increasing the determined transmit power level of the transmitter would violate an interference level limit within the spectrum hole.

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