High Dynamic Range Transceiver for Cognitive Radio

Abstract

Embodiments of cognitive radio technology can recover and utilize under-utilized portions of statically-allocated radio-frequency spectrum. A plurality of sensing methods can be employed. Transmission power control can be responsive to adjacent channel measurements. Digital pre-distortion techniques can enhance performance. Embodiments of a high DNR transceiver architecture can be employed.

What is claimed is: 
     
         1 . A heterodyne receiver system for cognitive radio comprising:
 a band selection filter selectively coupled with a first image rejection filter,   
       wherein the band selection filter is adapted to receive a first radio frequency signal and to selectively transmit a first specified frequency band, 
       thereby forming a first filtered signal, 
       wherein the first radio frequency signal comprises the first specified frequency band, 
       wherein the first specified frequency band comprises a first intended signal and a first image signal, 
       wherein the first intended signal has a carrier frequency, and, 
       wherein the first intended signal comprises a first specified channel;
 a first image rejection filter adapted to receive the first filtered signal, to selectively transmit the first intended signal, and to reject the first image signal, 
 
       thereby forming a second filtered signal;
 a first receiver mixer coupled with the first image rejection filter and adapted to combine the second filtered signal and a first tone signal, 
 
       thereby forming a modified second filtered signal, 
       wherein the first tone signal corresponds to a specified tone frequency;
 a first channel selection filter coupled with the first receiver mixer and adapted to receive the modified second filtered signal and to selectively transmit the first specified channel, 
 
       thereby forming a first specified channel signal, 
       wherein the first specified channel substantially resides within a specified passband, 
       wherein the specified passband overlaps a specified intermediate frequency, and, 
       wherein the specified intermediate frequency is selected from a set of intermediate frequency candidates; and,
 wherein the specified tone frequency is determined at least partially in response to at least the specified intermediate frequency, the carrier frequency, and the specified frequency band. 
 
     
     
         2 . The system of  claim 1  further comprising:
 a second receiver mixer coupled with the first channel selection filter and adapted to combine a second tone signal and the first specified channel signal, 
 
       thereby forming a modified first specified channel signal, 
       wherein the second tone signal corresponds to the specified intermediate frequency, and, 
       wherein the modified first specified channel signal comprises the first intended signal and a first alias signal. 
     
     
         3 . The system of  claim 2  further comprising:
 a receiver baseband filter coupled with the second receiver mixer and adapted to receive the modified first specified channel signal and to reject the first alias signal, 
 
       thereby forming a third filtered signal. 
     
     
         4 . The system of  claim 3  further comprising:
 an analog-to-digital converter coupled with the receiver baseband filter and adapted to convert the third filtered signal to a first digital signal. 
 
     
     
         5 . The system of  claim 1  further comprising:
 a second channel selection filter adapted to receive a modified fourth filtered signal and to selectively transmit a second specified channel, 
 
       thereby forming a second specified channel signal, 
       wherein the second specified channel substantially resides within the specified passband, and, 
       wherein the second specified channel comprises a second intended signal;
 a first transmitter mixer coupled with the second channel selection filter and adapted to combine the first tone signal and the second specified channel signal, 
 
       thereby forming a modified second specified channel signal, 
       wherein the modified second specified channel signal comprises a second image signal;
 a second image rejection filter adapted to receive the modified second specified channel signal and to reject the second image signal, 
 
       thereby forming a fifth filtered signal; and,
 wherein the band selection filter is selectively coupled with the second image rejection filter and adapted to receive the fifth filtered signal and to selectively transmit a second specified frequency band, 
 
       thereby forming a second radio frequency signal, 
       wherein the second radio frequency signal comprises the second specified frequency band, 
       wherein the second specified frequency band comprises the second intended signal, and, 
       wherein the first specified frequency band has a first set of specified boundaries, the second specified frequency band has a second set of specified boundaries, and the first set and second set of specified boundaries are essentially congruent. 
     
     
         6 . The system of  claim 5  further comprising:
 a digital-to-analog converter adapted to convert a second digital signal into a first analog signal, 
 
       wherein the second digital signal comprises the second intended signal, and, 
       wherein the first analog signal comprises a second alias signal;
 a transmitter baseband filter coupled with the digital-to-analog converter and adapted to receive the first analog signal and to reject the second alias signal, 
 
       thereby forming a fourth filtered signal;
 a second transmitter mixer coupled with the transmitter baseband filter and adapted to combine the fourth filtered signal and a second tone signal, 
 
       thereby forming the modified fourth filtered signal, 
       wherein the second tone signal corresponds to the specified intermediate frequency; and,
 wherein the second channel selection filter is coupled with the second transmitter mixer. 
 
     
     
         7 . A heterodyne receiver method for cognitive radio comprising the steps of:
 receiving a first radio frequency signal,   
       wherein the first radio frequency signal comprises a first specified frequency band, 
       wherein the first specified frequency band comprises a first intended signal and a first image signal, 
       wherein the first intended signal has a carrier frequency, and, 
       wherein the first intended signal comprises a first specified channel;
 filtering the first radio frequency signal to selectively transmit the first specified frequency band, 
 
       thereby forming a first filtered signal;
 filtering the first filtered signal to selectively transmit the first intended signal and to reject the first image signal, 
 
       thereby forming a second filtered signal;
 mixing the second filtered signal and a first tone signal, thereby forming a modified second filtered signal, 
 
       wherein the first tone signal corresponds to a specified tone frequency;
 filtering the modified second filtered signal to selectively transmit the first specified channel, 
 
       thereby forming a first specified channel signal, 
       wherein the first specified channel substantially resides within a specified passband, 
       wherein the specified passband overlaps a specified intermediate frequency, and, 
       wherein the specified intermediate frequency is selected from a set of intermediate frequency candidates; and,
 determining the specified tone frequency at least partially in response to at least the specified intermediate frequency, the carrier frequency, and the specified frequency band. 
 
     
     
         8 . The method of  claim 7  further comprising the step of:
 mixing a second tone signal and the first specified channel signal, 
 
       thereby forming a modified first specified channel signal, 
       wherein the second tone signal corresponds to the specified intermediate frequency, and, 
       wherein the modified first specified channel signal comprises the first intended signal and a first alias signal. 
     
     
         9 . The method of  claim 8  further comprising the step of:
 filtering the modified first specified channel signal by rejecting the first alias signal, 
 
       thereby forming a third filtered signal. 
     
     
         10 . The method of  claim 9  further comprising the step of:
 converting the third filtered signal to a first digital signal. 
 
     
     
         11 . The method of  claim 7  further comprising the steps of:
 filtering a modified fourth filtered signal by selectively transmitting a second specified channel, 
 
       thereby forming a second specified channel signal, 
       wherein the second specified channel substantially resides within the specified passband, and, 
       wherein the second specified channel comprises a second intended signal;
 mixing the first tone signal and the second specified channel signal, 
 
       thereby forming a modified second specified channel signal, 
       wherein the modified second specified channel signal comprises a second image signal;
 filtering the modified second specified channel signal by rejecting the second image signal, 
 
       thereby forming a fifth filtered signal; and,
 filtering the fifth filtered signal by selectively transmitting a second specified frequency band, 
 
       thereby forming a second radio frequency signal, 
       wherein the second radio frequency signal comprises the second specified frequency band, 
       wherein the second specified frequency band comprises the second intended signal, and, 
       wherein the first specified frequency band has a first set of specified boundaries, the second specified frequency band has a second set of specified boundaries, and the first set and second set of specified boundaries are essentially congruent. 
     
     
         12 . The method of  claim 11  further comprising the steps of:
 converting a second digital signal into a first analog signal, 
 
       wherein the second digital signal comprises the second intended signal, and, 
       wherein the first analog signal comprises a second alias signal;
 filtering the first analog signal by rejecting the second alias signal, 
 
       thereby forming a fourth filtered signal; and,
 mixing the fourth filtered signal and a second tone signal, 
 
       thereby forming the modified fourth filtered signal, 
       wherein the second tone signal corresponds to the specified intermediate frequency. 
     
     
         13 . A heterodyne transmitter system for cognitive radio comprising:
 a channel selection filter adapted to receive a first signal and to selectively transmit a specified channel,   
       thereby forming a specified channel signal, 
       wherein the first signal comprises an intended signal, 
       wherein the specified channel comprises the intended signal, 
       wherein the specified channel substantially resides within a specified passband, 
       wherein the specified passband overlaps a specified intermediate frequency, and, 
       wherein the specified intermediate frequency is selected from a set of intermediate frequency candidates;
 a transmitter mixer coupled with the channel selection filter and adapted to combine a first tone signal and the specified channel signal, 
 
       thereby forming a modified specified channel signal and a specified carrier frequency, 
       wherein the modified specified channel signal comprises an image signal, and, 
       wherein the first tone signal corresponds to a specified tone frequency;
 an image rejection filter coupled with the transmitter mixer and adapted to receive the modified specified channel signal and to reject the image signal, thereby forming a first filtered signal; 
 a band selection filter selectively coupled with the image rejection filter and adapted to receive the first filtered signal and to selectively transmit a specified frequency band, 
 
       thereby forming a radio frequency signal, 
       wherein the radio frequency signal comprises the specified frequency band, and, 
       wherein the specified frequency band comprises the intended signal; and,
 wherein the specified tone frequency is determined at least partially in response to at least the specified intermediate frequency, the carrier frequency, and the specified frequency band.