| The advantages of Code Division Multiple Access (CDMA) have made it become the core technology of the third generation wireless communication system, but the system performance and capacity is limited by the Mufti-Access Interference(MAI). Mufti-user Detection (MUD) is the key interference cancellation technology of the wideband CDMA communication system, the optimal MUD can overcome the MAI theoretically, but it can not be carried out under the current technological condition due to its high complexity. In order to solve the contradiction, people are searching for new sub-optimum MUD methods.Immune Genetic Algorithm is similar to Genetic Algorithm. It is a mixed improved Genetic Algorithm. The kernel idea is proposed to introduce many characteristics of Immune Genetic Algorithm on the basis of the frame of traditional Genetic Algorithm. The characteristics such as immune regulation mechanism, diversity, maintain strategy and so on. Immune Genetic Algorithm can effectively prevente immaturely restrains problems in search process, so it overcoms many insufficients of general Genetic Algorithm and it is a more effective optimized algorithm.This dissertation introduced the application of the spread spectrum technology in communications. Aiming characteristic in CDMA communication systems, Based on the discussion of some multi-user detection technology, an improvement algorithm was proposed that can enhance band width efficiency and reduce MAI in CDMA communication. On the basis of the research about Immune Genetic Algorithm, an Adaptive Immune Algorithm in CDMA multi-user detection was put foward. The computer simulative experiments were conducted by using the multi-user detection on the basis of Adaptive Immune Algorithm in synchronous CDMA system. The result proved that the use of this algorithm could improve the performance of system and that the performance of system is better than the decorrelating multi-user detection.Finally, the work of the dissertation is summarized, the further study and application of the CDMA multi-user detection is proposed. |
