Non-cooperative cross-channel gain estimation using full-duplex amplify-and-forward relaying in cognitive radio networks

Abstract

In this paper, we propose a new estimation method to obtain the cross-channel gain, which avoids the severe interference to the primary receiver (PR) in existing relay-assisted estimation methods. In our method, we let the cognitive transmitter add a time delay when it conducts the full-duplex amplify-and-forward relaying. This forces the time-difference-of-arrival (TDOA) between the direct and relay signals to be large enough rather than randomly large or small. Then we develop our estimation method only in the large TDOA case and precisely control the interference to the PR. Simulation results indicate that the proposed method can significantly reduce the interference to the PR.

Dynamic Spectrum Sharing in 5G Wireless Networks With Full-Duplex Technology: Recent Advances and Research Challenges

“…However, this approach may not be suitable for the scenarios causing large Time Difference of Arrivals (TDOAs) between the direct signal and the relayed signal since TDOA is a random variable and depends on the locations of the ST, PT and PR. To address this issue, authors in [141] proposed to introduce a time delay at the FD-based ST while performing AF relaying in order to force the TDOA to be large enough. Subsequently, an estimation algorithm was developed to estimate cross-channel gains in the large TDOA case and it has been shown that this delay-enabled method can precisely control the interference to the PR than the relay-assisted only approach.…”

“…In this context, FD relaying-assisted estimator has been proposed in [121] and a delay-enabled method in [141] towards the improving the PUs protection. Furthermore, improper Gaussian signaling at the SUs has been shown to be advantageous in an underlay spectrum sharing problem under certain conditions [138].…”