Research Of QoE-based Multimedia Transmission Strategies In Cognitive Radio Networks

The rapid development of wireless communication technology and prevalence of smart terminals lead to the rise of mobile internet. The increasing load of wireless communication services has made the current wireless spectrum resource insufficient to support people’s wireless communication applications. As a new technique to improve the utilization of spectrum resource, cognitive radio offers a way solve the problem of spectrum scarcity. In cognitive radio networks secondary users access the idle spectrum opportunistically and can get a relatively high transmission rate, which happens to satisfy people’s need for bandwidth-demanding multimedia transmission services. Therefore designing efficient multimedia transmission strategies in cognitive radio networks is pivotal to the improvement of system performance.This paper focuses on the multimedia transmission strategies in cognitive radio networks. Secondary users usually have different multimedia services and existent research about multimedia transmission strategies only considers users’requirement for Quality of Service (QoS). But it is the user experienced quality of service that really determines the performance of networks. Compared with QoS, quality of experience (QoE) is gaining more attention as a metric to evaluate the performance of network services because it directly reflects human’s satisfaction about services. Therefore, this paper adopts QoE as the measurement of service quality and uses the same QoE metric to unify different services for transmission optimization. Secondary users can access the spectrum owned by primary users in two ways:spectrum overlay and spectrum underlay. Multimedia transmission strategies are designed for the two access mode respectively in this paper.A transmission strategy is proposed for overlay cognitive networks. In the overlay access mode, primary users’arrival process on each channel is modeled as a Poisson process then the packet loss probability caused by collision between secondary users and primary users is estimated. With packet loss and data rate’s impact on QoE considered, the optimal transmission strategy is derived by cross-layer optimization. Simultaneously, fairness parameters are contained in the objective function to ensure fairness among secondary users. Lastly, simulation results prove that the proposed transmission strategy can obviously improve the mean QoE of all secondary users.A transmission strategy is proposed for underlay cognitive networks. In the underlay access mode, secondary users and primary users transmit data on the same spectrum, therefore secondary users has to control their transmission power to ensure primary users’normal communication. With transmission power limitation and data rate’s impact on QoE considered, the optimal transmission strategy is derived by cross-layer optimization which is solved like geometric programming. Simulation results show the proposed transmission strategy’s efficiency in improving the mean QoE of all secondary users.