Power control in cognitive radio systems based on spectrum sensing side information

Abstract

For cognitive radio systems, the transmit power of a cognitive radio device is controlled so that the cognitive, unlicensed radio device does not interfere with the use of a shared spectrum by a primary, licensed device. Controlling the transmit power includes determining a distance, or a function of the distance, between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process. The maximum transmit power of the cognitive radio device is then dynamically controlled based on the distance, or the function of the distance, while considering a worst case scenario of an underlying cognitive radio model, to guarantee a quality of service requirement of the primary device.

What is claimed is: 
     
         1 . A method comprising:
 controlling, by a system comprising a processing device, a transmit power of a cognitive radio device using an average probability of a missing energy detection of a primary transmitter of a primary device, wherein the missing energy detection is determined using sensing information associated with the cognitive radio device.   
     
     
         2 . The method of  claim 1 , wherein the controlling comprises controlling the transmit power of the cognitive radio device to satisfy a quality of service requirement for the primary device. 
     
     
         3 . The method of  claim 1 , further comprising:
 determining a distance parameter between the primary transmitter and the cognitive radio device using the average probability of the missing energy detection.   
     
     
         4 . The method of  claim 3 , wherein the controlling comprises:
 determining a maximum transmit associated with a quality of service requirement of the primary device based on a path loss function of the distance parameter; and   limiting the transmit power to the maximum transmit power.   
     
     
         5 . The method of  claim 3 , wherein the determining the distance parameter comprises:
 determining a plurality of candidate distances between the primary transmitter and the cognitive radio device using the average probability of the missing energy detection; and   setting the distance parameter to a shortest distance of the plurality of candidate distances.   
     
     
         6 . The method of  claim 1 , further comprising:
 determining the sensing information by monitoring an energy of a signal received by the cognitive radio device in a predefined bandwidth for a predefined period of time.   
     
     
         7 . A cognitive radio device, comprising:
 a memory, coupled to a processing device, that stores computer-executable instructions, comprising:   a control component configured to control a transmit power of a cognitive radio device using an average probability of a missing energy detection of a primary transmitter of a primary, wherein the missing energy detection is determined using sensing information associated with the cognitive radio device.   
     
     
         8 . The cognitive radio device of  claim 7 , wherein the control component is configured to control the transmit power of the cognitive radio device to satisfy a quality of service requirement for the primary device 
     
     
         9 . The cognitive radio device of  claim 7 , wherein the computer-executable instructions further comprise:
 a spectrum sensing component configured to determine a distance parameter between the primary transmitter and the cognitive radio device using the average probability of the missing energy detection.   
     
     
         10 . The cognitive radio device of  claim 9 , wherein the control component is further configured to:
 determine a maximum transmit power associated with a quality of service requirement using a path loss function of the distance parameter; and   prevent the transmit power from exceeding the maximum transmit power.   
     
     
         11 . The cognitive radio device of  claim 9 , wherein the spectrum sensing component is further configured to:
 identify a plurality of candidate distances between the primary transmitter and the cognitive radio device using the average probability of the missing energy detection; and   set the distance parameter to a shortest distance of the plurality of candidate distances.   
     
     
         12 . The cognitive radio device of  claim 7 , wherein the computer-executable instructions further comprise:
 a spectrum sensing component configured to determine the sensing information by monitoring energy of a signal received by the cognitive radio device in a predetermined spectrum for at least one predetermined time slot.   
     
     
         13 . A computer readable storage device comprising computer executable instructions that, in response to execution, cause a device comprising a processing device to perform operations, comprising:
 setting a transmit power of a cognitive radio device based on an average probability of a missing energy detection of a primary transmitter of a primary device, wherein the missing energy detection is based on sensing information associated with the cognitive radio device.   
     
     
         14 . The computer readable storage device of  claim 13 , wherein the setting comprises modifying a transmit power of the cognitive radio device based on the distance parameter to satisfy a quality of service requirement for the primary device. 
     
     
         15 . The computer readable storage device of  claim 13 , wherein the operations further comprise:
 estimating a distance parameter between the primary transmitter and the cognitive radio device based on the average probability of the missing energy detection.   
     
     
         16 . The computer readable storage device of  claim 15 , wherein the setting comprises:
 identifying a maximum transmit associated a quality of service requirement of the primary device based on a path loss function of the distance parameter.   
     
     
         17 . The computer readable storage device of  claim 16 , wherein the setting further comprises:
 setting the transmit power to the maximum transmit power.   
     
     
         18 . The computer readable storage device of  claim 15 , wherein the estimating comprises:
 estimating a plurality of candidate distances between the primary transmitter and the cognitive radio device based on the average probability of the missing energy detection.   
     
     
         19 . The computer readable storage device of  claim 18 , wherein the estimating further comprises:
 selecting a distance as a function of a shortest distance of the plurality of candidate distances as the distance parameter.   
     
     
         20 . The computer readable storage device of  claim 13 , wherein the operations further comprise obtaining the sensing information by monitoring energy of a signal received by the cognitive radio device in a predefined bandwidth for one or more predefined time intervals.