Research On Unequal Error Protection Based On Joint Coded Modulation

With the development of the third generation communication system, multimedia communication mainly for image and video is becoming more and more important and hot in the modern communication area. How to reduce the influence of channel errors and improve the transmission quality of image and video becomes a key problem of multimedia communication. Unequal error protection adopts different channel guarding schemes by the contribution of various parts of the bit stream to the quality of reconstructing source. Although it impairs the performance of less important bit stream, it improves the overall performance of the receiver.Firstly, this dissertation studies the joint coded modulation technology, including TCM, BICM, and BICM-ID. Then we analyze and compare their academic property over AWGN channel and flat fading channel. Additionally simulation is done to the joint coded modulation technology over the two kind channels.Then the dissertation studies the unequal error protection technology based on nonuniformly spaced constellations. Due to the characteristic of nonuniformly spaced constellations, this UEP technology doesn't need to use complex coder and decoder. Compared with the traditional UEP technology, this UEP system could be well simplified. Meanwhile, it can get different UEP property by altering the specified parameter of the nonuniformly spaced constellations instead of changing the coder and decoder, so it has strong adaptability.In order to improve the performance of UEP technology based on nonuniformly spaced constellations further, the dissertation applies the joint coded modulation technology to this UEP technology. According to the performance of joint coded modulation over different channel, we proposed the UEP technology based on TCM which suits the AWGN channel and the UEP technology based on BICM-ID which suits the flat Raleigh fading channel. At the same time, we simulate the two technology schemes and analyze and compare their simulation results.At last, the dissertation applies the UEP technology based on joint coded modulation to the transmission of image. Compared with the equal error protection (EEP) transmission, the simulation results show that the quality of image transmitted by UEP based on joint coded modulation is improved apparently.