Application of maximum-distance generalised quantiser for cooperative spectrum sensing in cognitive radio

To reduce the bandwidth requirement for reporting channel, the application of maximum-distance generalised quantiser for cooperative spectrum sensing (CSS) in cognitive radio is considered. The maximum-distance generalised quantiser, which uses Matsushita distance, is turn out to be a minimum mean square error quantiser of log-likelihood ratio (LLR) under absence hypothesis. Therefore the maximum-Matsushita distance quantiser CSS is achieved by utilising the well-known Lloyd-Max quantisation algorithm without the requirement of the prior probabilities of primary signal at each user. The probability density function of the LLR of the sensing information is also formulated for designing the quantiser. Simulation results reveal that the proposed quantiser with only few quantisation bits can provide the same sensing performance of the LLR test using raw data when primary signal has low signal-to-noise ratio.