近年來無線個人通訊系統快速成長，分碼多重存取（Code Division Multiple Access，簡稱CDMA）是第三代無線通訊系統之關鍵技術。然而CDMA網路之系統容量受雜訊干擾所限制，傳統的分頻多重存取（Frequency Division Multiple Access，簡稱FDMA）及分時多重存取（Time Division Multiple Access，簡稱TDMA）網路則受限於頻寬，且無線網路狀況亦常隨著週遭地形及所在位置之差異而增加決策之難度，因此需對呼叫允入控制（Call Admission Control，簡稱CAC）策略重新設計，使其能適用於CDMA網路中。 由於模糊邏輯控制（fuzzy logic control）有能力在資訊不夠完整時進行接近正確的決策，所以本論文以模糊邏輯技術應用於呼叫允入控制上，並佐以遺傳演算法（Genetic Algorithms，簡稱GA）調整模糊邏輯控制參數至近似最佳值。由模擬的結果得知在系統負載逐漸增加時，使用本論文所提策略可有效地控制遞交呼叫中斷機率，並可確保遞交呼叫之通訊品質。 Recently, the wireless personal communication system grows very fast and the CDMA has become the key technology for multiple accesses in the third generation wireless communication systems. Unlike conventional FDMA and TDMA systems, the capacity of CDMA is limited by the interference. Moreover, it is difficult to make call admission decisions under the wireless network conditions that are varying with the terrain and location. Therefore, a new call admission control policy is proposed to adapt to the changing network conditions for CDMA networks. Due to the fuzzy logic control has the capability to make decisions under ill-defined network environment, a call admission control policy using fuzzy logic control for CDMA networks is proposed in the thesis. The fuzzy rule set and the membership functions are obtained by using genetic algorithms to achieve the near-optimal solution. Simulation results show that, as the system load increases, the proposed CAC policy still can guarantee the dropping probability of handoff calls not beyond a pre-determined value and thus the quality of communications for handoff calls is offered.
