Spatial spectrum sensing algorithms for cognitive radios

Abstract

Cognitive radio is an artistic technology introduced to overcome the scarcity of electromagnetic spectrum. Spectrum sensing is key element in this technology. Many algorithms are proposed for said purpose but most of them are application specific and their performance degrades rapidly under particular conditions or they perform well but at the cost of high computational complexity. Keeping the advantages and disadvantages in view an adaptive spatial spectrum sensing algorithm is proposed for spectrum sensing. This algorithm adapts the spectrum sensing technique on the basis of channel conditions. If channel conditions are favorable it uses energy detection due to its simplicity and low computational complexity. If the channel goes under deep fading the receiver sense the channel conditions and switches toward the peak to average power ratio based spectrum sensing which outperforms under low signal to noise ratios on the cost of complexity. An analysis on the basis of complexity between energy detection and peak to average power ratio based sensing with proposed algorithm is performed. Simulation results are provided for the measurement of performance. Spatial Multiplexing is most widely used technique to overcome the effect of multipath fading. The advantage of diversity is used to further improve the performance of the cognitive radio system by applying multiple transmit and receive antennas. Simulation results are provided which compares the both adaptive spatial spectrum sensing algorithm and MIMO based algorithm in terms of probability of detection and probability of false alarm. Moreover space time coding is used for the purpose of improvement in spectrum sensing performance on the basis of Pd and Pfa. A better performance is achieved in the context of Pd and Pfa.