Research On Primary-secondary Cooperative Resource Allocation Techniques In Cognitive Radio Networks

The radio spectrum,which is needed for wireless communication systems,is a naturally limited resource.In the past decade,a number of advanced techniques have been proposed in the literatures,such as cognitive radio and cooperative communication.Cognitive radio is an emerging technology intended to enhance the utilization of the radio frequency spectrum.Owing to its remarkable performance,cooperative communication has become more and more attractive recently.Researches have shown that cooperative communication can offer significant performance enhancements in terms of increased capacity,improved transmission reliability,enhanced frequency reuse in a cellular deployment.By integrating cognitive radio with cooperative communication may further improve the future wireless network performance,however,it depends on all sort of resources can be efficiently utilized or not.In this article,a study on primary-secondary users,resource allocation in cooperative cognitive radio networks is investigated.The major contents and contributions are summarized as follows.Firstly,in a single primary user and single secondary user scenario,we propose a spectrum sharing cooperative transmission approach in which the secondary user receives data from the primary user in the first time slot,then in the second time slot acts as relay for the primary user and assists in the transmission of the primary user on some subcarriers.As a reward,the secondary user can transmit its own data on the remaining subcarriers.We obtain a power allocation and subcarrier assignment scheme by lagrangian multiplier method and dual-theory.Simulation results show that the proposed approach can make full use of time-frequency domain resources,contributing to a "win-win" situation for both the primary and the secondary user.Secondly,base on the above results,we consider a multiple primary users and multiple secondary users scenario further.Thanks to the feature of our scenario,we divide it into several independent parts and each with single primary user and multiple secondary users,making the optimization problem less complex.In our proposed scheme,multiple secondary users assist in the transmission of the same primary user on different subcarriers,and the subcarrier allocation gives consideration to the primary networks as well as the secondary networks.Analysis and numerical results illustrate that our scheme achieves about 5%performance increase over the comparison one.