A decoding-based fusion rule for cooperative spectrum sensing with nonorthogonal transmission of local decisions

Simin Bokharaiee,Ed Shwedyk,Ha H Nguyen

doi:10.1186/1687-1499-2013-184

Simin Bokharaiee, Ed Shwedyk + Show 1 more

Open Access

https://doi.org/10.1186/1687-1499-2013-184

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Abstract

Abstract Cooperative spectrum sensing in cognitive radio (CR) networks is studied in which each CR performs energy detection to obtain a binary decision on the absence/presence of the primary user. The problem of interest is how to efficiently report and combine the local decisions to/at the fusion center under fading channels. In order to reduce the required transmission bandwidth in the reporting phase, the paper examines nonorthogonal transmission of local decisions by means of on-off keying. Proposed and analyzed is a novel decoding-based fusion rule that essentially performs in three steps: (1) estimating minimum mean-square error of the transmitted information from cognitive radios, (2) making hard decisions of the transmitted bits based on the estimated information, and (3) combining the hard decisions in a linear manner. Simulation results support the theoretical analysis and show that the added complexity of the decoding-based fusion rule leads to a considerable performance gain over the simpler energy-based fusion rule when the reporting links are reasonably strong.

Highlights

Cognitive radio (CR) is an attractive technology to deal with the spectrum scarcity issue as the number of wireless applications and systems grows quickly
The fusion center aggregates the information pieces transmitted from the CRs and combines them according to some fusion rule in order to make a final decision about the absence or presence of the primary user in the band of the interest
It is pointed out that the simple expressions of the probability of false alarm and the probability of detection (Equations (18) and (19) for the energy-based fusion rule, or (36) and (37) for the decoding-based fusion rule) are very convenient in determining the threshold at the fusion center (λ(E) or λ(D)) for a given target probability of false alarm, and in evaluating the performance of different sets of signature vectors used in nonorthogonal transmission of local decisions

Summary

Introduction

Cognitive radio (CR) is an attractive technology to deal with the spectrum scarcity issue as the number of wireless applications and systems grows quickly. The technique of distributed spectrum sensing, in which the observations of CR nodes are collected and transmitted to a fusion center (FC) for a final sensing decision, has received a great interest in recent years. To further reduce bandwidth consumption while maintaining simple fusion processing, nonorthogonal transmission of local decisions can be employed by means of on-off keying (OOK) [1] In such a transmission technique, the CRs are allocated with nonorthogonal (correlated) signature vectors (SVs). The local decisions are transmitted to the fusion center over Rayleigh fading channels. For such transmission, the same framework presented in [1] is adopted. For a given sensing time, maximizing the throughput function for a target P D is equivalent to minimizing the probability of false alarm

Energy-based fusion rule

Simulation results

Findings

Conclusions