Beacon-Assisted Spectrum Access with Cooperative Cognitive Transmitter and Receiver

TL;DR

This paper introduces cooperative communication protocols for cognitive radios that enhance spectrum hole detection and capacity by dynamically assigning relays, analyzing the impact of detection errors and imperfect information exchange.

Contribution

It proposes novel cooperative models for spectrum access, including protocols with explicit information exchange, and evaluates their performance under realistic wireless conditions.

Findings

Cooperative protocols improve spectrum detection accuracy.

Imperfect information exchange reduces secondary channel capacity.

Bandwidth costs impact throughput in cooperative spectrum access.

Abstract

Spectrum access is an important function of cognitive radios for detecting and utilizing spectrum holes without interfering with the legacy systems. In this paper we propose novel cooperative communication models and show how deploying such cooperations between a pair of secondary transmitter and receiver assists them in identifying spectrum opportunities more reliably. These cooperations are facilitated by dynamically and opportunistically assigning one of the secondary users as a relay to assist the other one which results in more efficient spectrum hole detection. Also, we investigate the impact of erroneous detection of spectrum holes and thereof missing communication opportunities on the capacity of the secondary channel. The capacity of the secondary users with interference-avoiding spectrum access is affected by 1) how effectively the availability of vacant spectrum is sensed by the secondary transmitter-receiver pair, and 2) how correlated are the perceptions of the secondary transmitter-receiver pair about network spectral activity. We show that both factors are improved by using the proposed cooperative protocols. One of the proposed protocols requires explicit information exchange in the network. Such information exchange in practice is prone to wireless channel errors (i.e., is imperfect) and costs bandwidth loss. We analyze the effects of such imperfect information exchange on the capacity as well as the effect of bandwidth cost on the achievable throughput. The protocols are also extended to multiuser secondary networks.