The Research On The Coding Cooperative Diversity And Relay Technology In Wireless Communication Systems

Fading of wireless channels is an important factor which seriously degrades the performance of wireless communication system. Diversity technology is an effective method to resist fading. Spatial diversity is an effective diversity technology and thus very commonly used. Due to the use of multiple antennas, it does not require additional resources of time and frequency, and the diversity order is infinite. Limited by the dimension, weight, power consumption and cost of the terminal equipment of wireless networks, the installation of multiple antennas is very difficult to realize. Cooperative diversity is a kind of spatial diversity technology, which is realized by the cooperation among the wireless terminals each of which has only one antenna. The terminals build a virtual multiple antennas array by sharing their antennas. Cooperative relay technology is one of the key technologies in the decentralized wireless network. It is the relay that makes the communication between any two nodes of the network possible through the cooperation among the nodes. The cooperative diversity technology and cooperative relay technology are the key technologies of the next generation wireless networks. This dissertation focuses on the schemes and protocols of cooperative diversity and cooperative relay adopting code and modulation technology. The main content is as follows.1. The cooperative diversity technology based on channel code is researched. The general schemes of code cooperation are summarized. A cooperative diversity scheme based on LDPC code and another diversity scheme based on the combination of LDPC code and Alamouti's space-time code are developed, and their performances are analyzed and simulated.2. A cooperative diversity technology based on the rotated constellations technology is researched. A bandwidth-effective cooperative diversity scheme is proposed, which is realized by the cooperation between two wireless terminals, and the error rate performance is analyzed and simulated.3. A relay technology employing digital fountain code is researched. The relay schemes are developed in both the scenario when the relay nodes are static and that when the relay nodes are dynamic. Their performances are evaluated with regard to transmission time and transmission efficiency.4. A cooperative relay scheme using both fountain code and rotated constellation is developed, and its performance is analyzed and simulated.