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The probability density function of sum of a complex Gaussian and the product of two complex Gaussians is derived. This distribution occurs in wireless communications where Gaussian signals are transmitted over Rayleigh channels. The result is validated using the Kolmogorov-Smirnov distance and the accuracy of several approximations are compared, including fitted gamma and Nakagami distributions.
This paper presents a spectrum sensing algorithm for wideband interferers to be used within a cognitive radio. A two staged approach is proposed for the problem of wideband interferer detection. The first step requires that the frequency domain samples received are classified probabilistically amongst a number of possible statistical distributions, i.e. each sample is given a probability rating that...
Spectrum sharing systems such as cognitive radios must both strive to avoid interference and be tolerant to interference. While pilot symbol assisted systems have previously been shown to have detection and synchronization adversely affected by narrowband interference, the impact of wideband interference has received little attention. This paper shows both analytically and by computer simulation that...
This paper presents methods for enhancing blind spectrum sensing of wide-band signals using multiple antennas on a single cognitive receiver. Regulatory bodies in various countries have found that most radio spectrum is inefficiently utilized. Cognitive radio is a paradigm capable of utilizing bands assigned to licensed or primary users when they are not being used. A critical component of a functioning...
Cognitive radio technologies are being developed which allow heterogeneous systems to share spectrum access while minimizing interference to improve the overall efficiency of spectrum usage. Interference minimization requires cognitive radio receivers to be able to detect the presence of all other systems competing for spectrum usage, a process often termed "spectrum sensing". This paper...
Cognitive radio technologies are being developed which allow heterogeneous systems to share spectrum access while minimizing interference to improve the overall efficiency of spectrum usage. Interference minimization requires cognitive radio receivers to be able to detect the presence of all other systems competing for spectrum usage, a process often termed "spectrum sensing". However, the...
This paper introduces a combined geographic and a Media Access Control (MAC) protocol for mesh, ad-hoc and cognitive networks. For mesh and ad-hoc networks, this paper examines the end-to-end (source to destination) link performance characteristics when supporting multimedia traffic. This paper also explains the cognitive network concept prior to analyzing cognitive network related results. The performance...
This paper examines the end-to-end (source to destination) link performance characteristics when a novel media access control (MAC) protocol is used to support multimedia traffic in ad-hoc and mesh networks. The performance analysis was performed by a Monte Carlo simulator, the accuracy of which was verified by an analytical Markov model analysis. An overlaid cell structure was considered for the...
Signal spectra of wireless data systems are well known to be uncorrelated provided the communicated data sequence itself is white. However, multiplicative processes in wireless transmission systems and multipath fading channels produce spectral correlation. This paper shows that, where spectrum sensing opportunities are short in duration, the sample vector spectrum covariance matrix typically remains...
The effect of narrowband interference on OFDM systems is considered, with particular regard to the receiver post-detection bit error rate performance. It is shown both by analysis and by computer simulation that the ensemble average bit error rate is severely affected by narrowband interference and that particular values of interferer carrier frequency and phase can produce bit error rates significantly...
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