Power and sub-channel optimization of JPEG 2000 image transmission over OFDM-based cognitive radio networks

Cognitive Radio is an efficient way of spectrum utilization since secondary users with bandwidth-demanding applications such as multimedia can get access to licensed frequency resources opportunistically and resolve their bandwidth limitations. Among all multimedia formats, JPEG 2000 is a suitable candidate for cognitive radio networks thanks to its unique features. In conventional resource allocations for Cognitive Radio systems, all data bits are assumed equally important. However, different parts of the JPEG 2000 bit stream have different contributions to the quality of the received image. Therefore, in this paper, an unequal power allocation method is used to allocate the available power to the coded bits based on their importance in the image quality. Simulated annealing method is used to solve the unequal power allocation problem. Furthermore, bits with higher significance are further protected by using sub-channels with better channel quality. Thus, the likelihood of significant bits being received correctly is increased. The optimal solution is obtained by minimizing the image distortion without violating the interference constraint to the primary users. The performance of the proposed method is demonstrated by simulation results.