具時效性資料無線傳輸之跨層最佳化

Abstract

隨著科技日益進步，無線多媒體之應用愈來愈普及。例如：行動電視，無線網路電話和視訊會議等等。多媒體為一即時性之應用，故此對於延遲、時延抖動以及封包遺失非常敏感。由於無線通道之變異性相當大，容易造成封包遺失，封包延遲抵達目的地，以及時延抖動之增大。因此在無線環境裡傳送即時性的應用是極具挑戰的。本論文之貢獻如下：(1)分析在無線通訊系統裡，具時效性封包之遺失率，並提出最佳的傳輸封包方法以獲得最低之遺失率； (2)針對影像傳輸之應用，分析視頻禎之遺失率，並提出最佳的封包傳輸方法使得影像品質最高。(3)分析無線通訊系統所造成的時延抖動之機率分佈，以便接收端設計最佳的播放緩衝時間；理論分析與模擬結果之吻合，驗證了理論分析之準確性。本論文之研究能應用於基地台、無線存取點，以及合作式通信中傳輸節點之具時效性封包傳輸。

Nowadays, the applications of real-time data transmissions in the Internet become more and more popular, such as mobile TV, VoIP, video conference, and etc. However, the real-time data is extremely sensitive in delay, delay jitter and packet loss, so that it is challenging to transmit the delay sensitive data over the wired network and the wireless network. Our goals is to design the optimal schemes for delay sensitive packet transmissions. There are three main contributions in the thesis: (1) analyses the packet error rate (PER) which combines the nite queueing behavior and the wireless transmission with Adaptive Modulation and Coding (AMC). The optimal transmission scheme is then proposed for minimizing PER. (2) is to analyse the video frame error rate (VFER) and evaluate the video quality. The optimal transmission scheme is then proposed to maximize video quality. (3) is to analyse the delay jitter distributions for the optimal bu ering design for the receivers. The simulation results matching with the analytical results prove the accuracy of theoretical analysis. The theoretical analysis and optimal transmission schemes can be applied to the devices which transmit delay sensitive data, such as base station, wireless Access Points, relay nodes in cooperative communication, and etc.