Full Duplex Wireless Communications for Cognitive Radio Networks

TL;DR

This paper introduces a full duplex wireless communication scheme for cognitive radio networks that enables secondary users to detect primary users while transmitting, significantly reducing primary user packet loss compared to traditional half duplex systems.

Contribution

The paper proposes a novel full duplex scheme with specific interference cancellation techniques, allowing secondary users to detect primary users during transmission, which is a significant advancement over existing half duplex methods.

Findings

Packet loss rate of primary users is significantly reduced.

Full duplex CRNs outperform half duplex CRNs in primary user packet loss.

Simulation results validate the effectiveness of the proposed scheme.

Abstract

As a key in cognitive radio networks (CRNs), dynamic spectrum access needs to be carefully designed to minimize the interference and delay to the \emph{primary} (licensed) users. One of the main challenges in dynamic spectrum access is to determine when the \emph{secondary} (unlicensed) users can use the spectrum. In particular, when the secondary user is using the spectrum, if the primary user becomes active to use the spectrum, it is usually hard for the secondary user to detect the primary user instantaneously, thus causing unexpected interference and delay to primary users. The secondary user cannot detect the presence of primary users instantaneously because the secondary user is unable to detect the spectrum at the same time while it is transmitting. To solve this problem, we propose the full duplex wireless communications scheme for CRNs. In particular, we employ the Antennas Cancellation (AC), the RF Interference Cancellation (RIC), and the Digital Interference Cancellation (DIC) techniques for secondary users so that the secondary user can scan for active primary users while it is transmitting. Once detecting the presence of primary users, the secondary user will release the spectrum instantaneously to avoid the interference and delay to primary users. We analyze the packet loss rate of primary users in wireless full duplex CRNs, and compare them with the packet loss rate of primary users in wireless half duplex CRNs. Our analyses and simulations show that using our developped wireless full duplex CRNs, the packet loss rate of primary users can be significantly decreased as compared with that of primary users by using the half duplex CRNs.