Channel state prediction in cognitive radio, Part II: Single-user prediction

Response delay problem and measurements of such delays have been reported in Part I. The response delay has a negative impact on the accuracy of spectrum sensing, which is the cornerstone of cognitive radio. In this paper, single-user prediction of channel state is proposed to minimize the negative impact of response delays caused by hardware platforms. Specifically, a modified hidden Markov model (HMM) based single-secondary-user (single-SU) prediction is proposed and examined. In order to have convincing performance evaluation results, real-world Wi-Fi signals are employed to test the proposed approach, where the Wi-Fi signals are recorded at four different locations simultaneously. Experimental results show that the proposed single-SU prediction outperforms the 1-nearest neighbor (1-NN) prediction which uses a detected current state as an estimate of future states. This work is a part of the effort toward building a cognitive radio network testbed.