Title :
On the Need for Knowledge of the Phase in Exploiting Known Primary Transmissions
Author :
Grover, Pulkit ; Sahai, Anant
Author_Institution :
Univ. of California at Berkeley, Berkeley
Abstract :
Recently Tarokh and others have raised the possibility that a cognitive radio might know the interference signal being transmitted by a strong primary user in a non-causal way and use this knowledge to increase its data rates. However, there is a subtle difference between knowing the signal transmitted by the primary and the actual interference experienced at our receiver since there is a wireless channel between these two points. We show that even an unknown phase results in a substantial decrease in the data rates that can be achieved, and thus there is a need to feedback interference channel estimates to the cognitive transmitter. We give a scheme that uses appropriate "training" to obtain such estimates and quantify this scheme\´s required overhead as a function of the relevant coherence time and interference power.
Keywords :
cognitive radio; interference; radio networks; wireless channels; cognitive radio; cognitive transmitter; data rates; feedback interference channel estimation; interference power; receiver; wireless channel; Cognitive radio; Coherence; Fading; Feedback; Interference channels; OFDM; Phase estimation; Radio transmitters; Receivers; Uncertainty;
Conference_Titel :
New Frontiers in Dynamic Spectrum Access Networks, 2007. DySPAN 2007. 2nd IEEE International Symposium on
Conference_Location :
Dublin
Print_ISBN :
1-4244-0663-3
DOI :
10.1109/DYSPAN.2007.67