Research On The Next Generation Wireless Network Resource Allocation Technology In Cooperative And Cognitive Communications

The development of wireless communication is always pursuing faster transmission rate and better service quality, but limited wireless resource has become the bottleneck problem that drags the wireless communication from fast moving forward. So, more reasonable and optimal resource allocation method is crucial for improving the performance of current communication system. At the same time, researchers constantly look for new technologies to increase network capacity and optimize network performance. Technologies that can further improve system throughput and spectrum efficiency such as cooperative communication, cognitive radio and so on are introduced into the next generation wireless network.Cooperative communication technology changes traditional single direct transfer mode, and increase the spectrum utilization and transmission reliability because of the diversity gain generated by multipath transmission. What’s more, cooperative transmission between users saves the overhead of relay nodes and makes cooperation more flexible. But which user is selected for cooperation, which method is employed for resource allocation between cooperative users play decisive roles in cooperative performance.Cognitive radio technology breaks the bondage of current fixed spectrum allocation policy. By dynamic spectrum sensing and opportunistic spectrum accessing, cognitive radio can vastly increase the spectrum efficiency. But how to effectively use and allocate the spectrum resource are problems need to be solved in cognitive radio network. For cooperative communication, this article proposes a multi-service mixed resource allocation method. In a system model with both Real-Time and Best-Effort users, the QoS requirements and differences are considered to resolve the relay node, relay strategy selection and sub-carrier, power allocation problems. The method aims to increase the overall system throughput while satisfy QoS of both users at the same time. For cognitive radio network that primary user coexist with secondary user in underlay method, this article investigates a network coding based OFDMA cooperative transmission scheme. Considering the fairness between secondary users, it adopts Nash bargaining theory to solve the resource allocation between cooperative user pair. Then, the two user scenario is expanded into more secondary users, and the collaborative user selecting problem is settled. The proposed scheme can achieve relatively high user fairness and system throughput.