Joint Resource Allocation In Cognitive Radio Network

With traditional static human spectrum allocation policy, a large number of available spectrum are leaving idle and waste. As a dynamic spectrum access technology, cognitive radio technology is generally considered to be the best solution of the low utilization of wireless spectrum resource. With the intelligent detection ability, cognitive equipment is able to sense and rational use the spectrum hole as much as possible to improve spectrum utilization, while avoiding the interference to other users.Cognitive users can access the spectrum hole to improve spectrum efficiency in wireless communication. For the under utilized spectrum distributed in different geographical locations and time dimension, how to allocate spectrum to multiple independent cognitive users and power to these spectrum to maximize the system throughput is an important issue in cognitive radio resource allocation. In the actual cognitive radio network, different spectrum that cognitive users choose to access has different power allocation. On the other hand, different power allocation on spectrum holes lead to different channel capacity, SINR, etc., which act as performance indicators spectrum allocation. Therefore, the spectrum allocation and power allocation are coupled together and should be considered jointly to optimize system performance.Research on joint resource allocation in cognitive radio network are based on opportunistic spectrum access, spectrum sharing access as well as hybrid spectrum access. And joint resource allocation based on the hybrid spectrum access scheme can improve the network performance effectively, where cognitive users can access all the licensed channel at any time no matter the primary users (PUs) are idle or not. However, related studies are all based on the communication between a single SU pair, where only power allocation among the accessed channels under different channel status and interference constraints are involved. And the previous research cannot be applied to the general scene of multiple cognitive user communication where multiple independent SUs are exploiting to access all the licensed channel under hybrid scheme. In the general scene of multiple cognitive user communication, we need to consider the channel allocation where multiple independent cognitive users are exploiting to access all the licensed channel under hybrid scheme, and power allocation to this channel under different channel status. Besides, different data demand of cognitive users and the interference among cognitive users in multiuser environment are taken into account.To solve the problem above, we propose a joint resource allocation algorithm based on the hybrid scheme in multi-user cognitive radio network. With these coupled inequality constraints of traffic demand, transmit power constraints and interference of cognitive users, Lagrange dual composition method is introduced for this nonlinear optimization problem. Exact expressions of power allocation and the channel allocation scheme are derived under power and interference limits and QoS demands. Simulation results are presented to verify the influencing factors and advantage of the proposed algorithm compared to opportunistic spectrum access. And the applicable scenario of the proposed algorithm are analyzed.