Influência da Quantização no Sensoriamento Espectral via Teorema dos Círculos de Gerschgorin

Abstract

Resumo-No sensoriamento espectral cooperativo centralizado rádios cognitivos monitoram faixas do espectro e enviam dados a um centro de fusão para detectar, mais acuradamente, faixas ociosas. Na prática, tais dados são quantizados antes do envio, podendo gerar perda de desempenho devidoà distorção. Dentre outras vantagens, o novo detector baseado no Teorema dos Círculos de Gerschgorin (Gerschgorin radii and centers ratio, GRCR) mostrou-se robusto em cenários práticos, por exemplo, sob o efeito do ruído dinâmico e/ou não uniforme, contudo ainda não testado sob o efeito da quantização. Este artigo faz essa análise e mostra que o GRCR tambémé robusto neste cenário. Nota-se que a quantização uniforme pode ser preferida em alguns casos. Palavras-Chave-Sensoriamento espectral, detector GRCR, quantização uniforme e não uniforme.

Performance of the Gerschgorin Radii and Centers Ratio Detector for Cooperative Spectrum Sensing under Burst Control Channel Errors

“…After the publication of [8], the performance of the GRCR detector has been the subject of a few research, for instance [1], where the errors induced by uniform and nonuniform quantizers were investigated under nonuniform noise across the CRs. The results in [1] show that uniform quantization may be preferred when the number of quantization bits is greater than 2, because of the lower complexity and the absence of need for knowing the statistics of the signal to be quantized. As far as quantization is concerned, an scheme based on the Kullback-Leibler divergence is proposed in [9] in order to reduce the amount of data in the control channel.…”

“…The importance of reducing the amount of data in the control channel and the robustness of the test statistic against the signal distortion due to quantization with low resolution are the focus of [1], [9]- [11]. However, the bit errors produced during the transmission to the FC have not been considered, i.e., the control channel has been considered error-free.…”

“…In summary, [1], [9]- [14] consider quantization errors in some cases, and in others the effects of the quantization errors are added to the errors produced by the control channel. To the best of our knowledge, no analysis has been made assuming burst errors in the information transmitted to the FC.…”

“…Since this type of error is common in a wireless mobile channel, it is important to consider it in performance analyzes of spectrum sensing schemes. Therefore, in this article, which is an extension of the research presented in [1], we consider the effects of burst errors in the control channel and the problem of signal distortion caused by two nonuniform (nonlinear) quantization methods and a uniform (linear) one, in the centralized CSS with sample fusion, applying the GRCR detector as the test statistic at the FC. Our results show that: i) the GRCR detector is robust in the scenarios analyzed, ii) the uniform quantization may be preferred in some cases when the control channel is assumed to be perfect, iii) the nonuniform quantization attains better performance under errors in the control channel, and iv) the effect of memory in the control channel can generate performance gains with respect to the memoryless channel (especially with uniform quantization) when both are subjected to the same average bit error probability.…”

“…The research reported in [1] analyzes the effect of quantization on the performance of the GRCR detector in centralized CSS with sample fusion. The samples in each CR are quantized in three different ways: i) standard uniform quantization, ii) nonuniform quantization under the maximum output entropy (MOE) design criterion, and iii) nonuniform quantization under the minimum mean square error (MMSE) design criterion.…”