- 學位論文
指向型陣列天線對多目標
Multi-Objective Optimization for Directional Antenna Arrays
摘要
本論文在一個室內超寬頻系統環境下模擬，分別測試了將8根發射天線以及8根接收天線做環型陣列的擺設，以及將8根發射天線以及1根接收天線做環型陣列的擺設，分別利用射線彈跳追蹤法計算出任意給定室內無線環境之脈衝響應，在發射端與均使用波束合成的技術，接收端為8根天線的亦使用波束合成的技術，使能量聚焦，減少通道之間的多路徑效應干擾；接收端為單根天線的則只有發射端使用波束形成技術，以此做出差異性來做比較。發射端和接收端同時利用自我適應之動態差異型演化法(Self-Adative Dynamic Differential Evolution, SADDE)以及粒子群聚最佳化法(Particle Swarm Optimization,PSO)來調整天線的激發電流及每一根陣列元素上的饋入線長度，並以降低傳輸位元錯誤率、提高通道容量以及提高接收端做為目標函數，所搜尋到的天線輻射場型能滿足良好的通訊品質。 根據室內超寬頻的環境裡，增加接收端的天線模擬結果顯示，在接收端使用波束合成的技術比起在接收端只放單一一根天線的狀況下，使發射與接收天線合成出更具指向性的輻射場型，傳輸能量因而提升，更能降低位元錯誤率。而使用SADDE演算法的情況下，不論收斂速度或是適應值都優於PSO粒子群演算法。
並列摘要
In this paper, ultra-wide band communication systems with eight transmit ring antenna arrays are implemented to test the bit error rate and capacity performance of the receivers with single antenna and eight antennas respectively. By using the ray tracing technique to computer any given indoor wireless environment, the impulse response of the system can be calculated. The synthesized beamforming problem can be reformulatedinto a multi-objective optimization problem. Self-adaptive dynamic differential evolution (SADDE) and particle swarm optimization (PSO) are used to find the feed line length of each antenna to form the appropriate beam pattern. This pattern can reduce bit-error rate,increase channel capacity and receiving energy.Numerical results show that receiver with eight antennas can reduce BER and increase the capacity substantiallycompared to single antenna receiver. It is also found the fitness value and convergence speed by SADDEis better than those by PSO. Moreover, SADDE can get better resultsfor both line-of-sight and non line-of-sight cases