Genetic-Algorithms-Based Fuzzy Call Admission Control for CDMA Cellular Systems

Wireless personal communication systems grow very fast, and the Code Division Multiple Access (CDMA) system has become the key technology for multiple accesses in the third generation communication systems. Unlike conventional FDMA and TDMA systems, the capacity of CDMA is limited by the interference. Moreover, the quality of the wireless communications varies with the terrain and the location, and thus it is difficult to make decisions for call admissions. In the paper, a call admission control (CAC) scheme is proposed to adapt to the changing wireless network conditions for CDMA systems. Due to the fuzzy logic control has the capability to make decisions under the ill-defined network environment, the proposed CAC scheme is based on the fuzzy logic control, where the fuzzy rule sets and the membership functions are obtained by using genetic algorithms to achieve the near-optimal solution. Simulation results show that, even at the heavy load, the proposed CAC policy is capable of guaranteeing the dropping probability of handoff calls to meet a predefined value. Key-Words: call admission control, Code Division Multiple Access, fuzzy logic control, genetic algorithms The research was supported by Ministry of Education of the Republic of China under contract A-91-H-FA07-1-4.