Design And Implementation Of Video Transmission In Cognative Radio System

With the rapid development of science and technology, wireless communication plays a more and more important part in daily lives. However, due to the fixed spectrum allocation policy, spectrum utilization gets lower and spectrum resources become scarce, which have been a major factor of restricting the wireless communication development. The proposed idea of cognitive radio shows people an effective solution of low spectrum utilization problem. The idea has been a hot research topic in wireless communication field.Work mentioned in this paper, relied on 863 projects, is aimed at improving the original cognitive radio hardware platform in the laboratory. The original platform supports many functions including spectrum sensing, spectrum access and spectrum handover. Voice service and low rate data service can also be found. Nonetheless, there are some disadvantages. In spectrum sensing module, there are some shorts such as rare sampling points, inadequate judging mechanisms, and large delay in frequency handover. All these above will affect the system performance. In addition, rare kinds of service model in this system are not sufficient in verifying the algorithms about high rate service model.In this paper, spectrum sensing and service model are the main points to be improved. In addition to get an optimization in sensing accuracy and shorten the sensing time, more sampling points will be added and a new switching method will be introduced to decrease the delay. Besides mentioned above, video transmission model will be added. Compared with voice and low rate data model, video transmission model has the characteristics of high rate, wide bandwidth and low latency. In cognitive radio environment, because of the limited bandwidth and the influence brought by other users, design and implementation of video transmission model in the hardware platform is necessary and a number of issues will be studied.Optimization in this paper is based on the original Universal Software Radio Peripheral hardware platform. The optimized platform can achieve a more accurate result of the surrounding environment spectrum utilization within a shorter time. It can select the most appropriate spectrum hole for video transmission and reserve the suboptimal hole for spectrum handover.This last section of the paper describes that the hardware platform is tested in a real environment and get a close result with expectations.