Indirect Channel Sensing for Cognitive Amplify-and-Forward Relay Networks

TL;DR

This paper proposes an indirect primary channel sensing method for cognitive amplify-and-forward relay networks, enabling cognitive radios to estimate channels without modifying primary receivers or using extra spectrum.

Contribution

It introduces a novel indirect sensing approach utilizing relay retransmissions, combined with least squares and sparse estimation techniques, to improve channel estimation in cognitive AF relay networks.

Findings

The method achieves acceptable channel estimation performance.

It avoids the need for primary receiver modifications.

It effectively handles dense and sparse multipath channels.

Abstract

In cognitive radio network the primary channel information is beneficial. But it can not be obtained by direct channel estimation in cognitive system as pervious methods. And only one possible way is the primary receiver broadcasts the primary channel information to the cognitive users, but it would require the modification of the primary receiver and additional precious spectrum resource. Cooperative communication is also a promising technique. And this paper introduces an indirect channel sensing method for the primary channel in cognitive amplify-and-forward (AF) relay network. As the signal retransmitted from the primary AF relay node includes channel effects, the cognitive radio can receive retransmitted signal from AF node, and then extract the channel information from them. Afterwards, Least squares channel estimation and sparse channel estimation can be used to address the dense and sparse multipath channels respectively. Numerical experiment demonstrates that the proposed indirect channel sensing method has an acceptable performance.