Transmit power control techniques for wireless communication systems

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.

1 . A device for controlling transmit power in a multi-user cognitive radio network, the device comprising:
 a transceiver and one or more antennas; and   a processor coupled to the transceiver and to a memory, the processor being configured to determine a transmit power level for a transmitter in the transceiver according to an iterative water-filling procedure and to monitor transmit behavior of other transmitters using a learning algorithm,   transmit behavior of other transmitters being monitored through a receiver of the transceiver and the one or more antennas.   
     
     
         2 . The device of  claim 1 , wherein the one or more antennas comprise a MIMO (Multiple-Input Multiple Output) antenna architecture. 
     
     
         3 . The device of  claim 1 , wherein the device comprises a mobile communication device. 
     
     
         4 . The device of  claim 1 , wherein the device comprises a base station. 
     
     
         5 . The device of  claim 1 , wherein the device comprises equipment in a wireless communication system. 
     
     
         6 . The device of  claim 1 , wherein the processor is further configured to implement a cognitive radio. 
     
     
         7 . The device of  claim 1 , wherein the iterative water-filling procedure comprises:
 initializing a transmit power distribution across n transmitters;   performing water-filling for the transmitter of the transceiver 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 adjusting the determined transmit power level for the transmitter based on the determination;   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 on determining that the target data transmission rate of at least one of the n transmitters is not satisfied.   
     
     
         8 . The device of  claim 7 , 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 on determining that the target data transmission rates of all of the n transmitters are not satisfied. 
     
     
         9 . The device of  claim 7 , wherein the processor 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 on determining that 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 on determining that increasing the determined transmit power level of the transmitter would not violate an interference level limit.   
     
     
         10 . The device of  claim 9 , 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, on determining that the data transmission rate of the transmitter is less than the target data transmission rate of the transmitter and that increasing the determined transmit power level of the transmitter would violate an interference level limit within the spectrum hole. 
     
     
         11 . The device of  claim 1 , 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. 
     
     
         12 . The device of  claim 11 , 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. 
     
     
         13 . The device of  claim 11 , wherein the processor is further configured to predict subsequent availability of the at least one spectrum hole, and to determine a new transmit power level on predicting that the at least one spectrum hole is to become unavailable. 
     
     
         14 . The device of  claim 11 , wherein the processor is further configured to detect a further spectrum hole, to monitor interference in the at least one spectrum hole, and to determine a new transmit power level for the transmitter for transmission within the further spectrum hole on detecting an increase in interference in the at least one spectrum hole. 
     
     
         15 . The device of  claim 1 , wherein the processor is further configured to determine a position of the transmitter relative to the other transmitters, 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. 
     
     
         16 . The device of  claim 1 , wherein the learning algorithm comprises a regret-conscious learning algorithm or a Lagrangian learning algorithm. 
     
     
         17 . A method for controlling transmit power in a multi-user cognitive radio network, the method comprising:
 determining a transmit power level for a transmitter of a transceiver according to an iterative water-filling procedure; and   monitoring transmit behavior of other transmitters using a learning algorithm,   the monitoring comprising monitoring transmit behavior of the other transmitters through a receiver of the transceiver.   
     
     
         18 . The method of  claim 17 , wherein the iterative water-filling procedure comprises:
 initializing a transmit power distribution across n transmitters;   performing water-filling for the transmitter of the transceiver 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 adjusting the determined transmit power level for the transmitter based on the determination;   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 on determining that the target data transmission rate of at least one of the n transmitters is not satisfied.   
     
     
         19 . The method of  claim 18 , wherein the 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. 
     
     
         20 . The method of  claim 19 , 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 n transmitters are not satisfied, and repeating the operation of performing water-filling on determining that the target data transmission rates of all of the n transmitters are not satisfied. 
     
     
         21 . The method of  claim 18 , wherein adjusting comprises:
 determining whether increasing the determined transmit power level of the transmitter would violate an interference level limit on determining that 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 on determining that increasing the determined transmit power level of the transmitter would not violate an interference level limit.   
     
     
         22 . The method of  claim 21 , 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:
 detecting a further spectrum hole; and   determining a further transmit power level for the transmitter for transmission within the further spectrum hole, on determining that the data transmission rate of the transmitter is less than the target data transmission rate of the transmitter and that increasing the determined transmit power level of the transmitter would violate an interference level limit within the spectrum hole.   
     
     
         23 . The method of  claim 21 , further comprising:
 adapting a modulation strategy for transmission of data by the transmitter on determining that 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.   
     
     
         24 . The method of  claim 17 , further comprising:
 detecting at least one spectrum hole,   wherein determining a transmit power level comprises determining a transmit power level for the transmitter for transmission within the at least one spectrum hole.   
     
     
         25 . The method of  claim 24 , wherein the at least one spectrum hole comprises a plurality of spectrum holes, and wherein determining a transmit power level comprises determining a set of transmit power levels comprising multiple transmit power levels for transmission within respective ones of the plurality of spectrum holes. 
     
     
         26 . The method of  claim 24 , further comprising:
 predicting subsequent availability of the at least one spectrum hole; and   determining a new transmit power level on predicting that the at least one spectrum hole is to become unavailable.   
     
     
         27 . The method of  claim 24 , further comprising:
 detecting a further spectrum hole;   monitoring interference in the at least one spectrum hole; and   determining a new transmit power level for the transmitter for transmission within the further spectrum hole on detecting an increase in interference in the at least one spectrum hole.   
     
     
         28 . The method of  claim 17 , further comprising:
 determining a position of the transmitter relative to the other transmitters; 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.   
     
     
         29 . The method of  claim 17 , wherein the learning algorithm comprises a regret-conscious learning algorithm or a Lagrangian learning algorithm. 
     
     
         30 . A non-transitory machine-readable medium storing instructions which when executed perform the method of  claim 17 . 
     
     
         31 - 153 . (canceled)