Research On Video Transmission Technology In Broadband Wireless Trunking

As broadband wireless transmission technology has become more sophisticatedand the demanding of private network such as public safety network for video andother data services has increased rapidly, trunking communication system isgradually evolving towards broadband. A new generation trunking communicationsystem-Broadband Wireless Trunking (BWT) has received more and more attentionin academia and industry field.Compared to traditional narrowband trunking systems, the wireless accessbandwidth of BWT has been greatly improved, making it possible to supportsefficient wireless video transmission services. Compared with other videotransmission systems, BWT supports three wireless access modes: medium-speed,high-speed and ultra-high-speed. So video transmission algorithm must be deeplystudied to simultaneously accommodate three different wireless access bandwidths.Regarding to video distribution business in BWT, the paper focused on unequalerror protection, which was based on a joint source-channel coding algorithm inorder to improve the recovery video quality in three different access modes whilereducing complexity of the algorithm. The research has important practicalsignificance in the realization of using multiple access modes for video transmissionto meet the users’ needs in BWT. And it also has a certain theoretical reference valuefor video compression algorithm in the video transmission system which hasvariable bandwidth.Firstly, the paper presents a joint source-channel bits allocation algorithmswhich can adapt to different target rate with lower computational complexity in thecase that several groups of channel codes with different rates has been given. Thealgorithm includes intra-frame forward planning algorithm and inter-frame bitallocation algorithm. When calculated the rate-distortion curve for each frame, firstovercomes the deficiencies of original enhancement layer contribution distortionmodel by adding two variable parameters. Simulation results show that theimprovement can enhance the quality of recovery of the received video. At the sametime aiming at high computational complexity, an optimization grid algorithm hasalso been proposed, which has greatly reduced the amount of computation withoutchanging the final calculations cases by deleting unreasonable branch path inadvance. During the inter-frame bit allocation, the paper presents a GOP-based bitallocation method-slope search algorithm, make full use of the rate-distortion information of each frame within a GOP. The simulation results show that thereconstructed video quality has a certain increase compared with the traditionalbisection algorithm.Finally, bit allocation algorithm is applied to the BWT, and a video distributionsystem is designed based on the slope search algorithm. The analysis results showthat server processing cost is proportional to the numbers of the kinds of all theusers’ channels’ SNR in the system, while having little relationship with the numberof users. And the simulation results show that the system can adapt to differentwireless access mode of different users.