WiMAX系統下兩階級數據的數據映射演算法之改進

Abstract

IEEE 802.16e標準，採用OFDMA PHY一般被稱為行動WiMAX (Mobile WiMAX)， 在過去的幾年中已經引起了無線通信業界的關注。它是一個基於IP網路的高速遠距離無線寬帶接取技術的優化。在行動WiMAX系統的下行鏈路，數據都被映射到矩形區域。在矩形的限制下，最大化吞吐量是一個NP完全問題。過去有一些啟發式數據映射算法被提出，他們試圖實現系統的高吞吐量。其中有大多數的演算法只處理一種類型的數據。在最近的研究中，一個可映射兩級別的數據請求（即緊急和非緊急數據）的數據映射演算法被提出。然而，它在決定數據映射的順序時卻只有考慮數據請求所需的槽數量。 在這篇論文中，我們提出的增強版本，同時考慮每個行動用戶所需的槽數量和所使用的調變編碼機制。模擬結果顯示，與以前的設計相比，增強的演算法能為緊急數據提供更高的吞吐量。

The IEEE 802.16e standard, which adopts OFDMA PHY and is generally known as Mobile WiMAX, has grabbed the attention of wireless communication industry for the past few years. It is a technology optimized for IP-based high speed long-distance wireless broadband access. In the downlink of Mobile WiMAX systems, data requests have to be mapped into rectangular regions. Such a constraint results in an NP-complete problem in order to maximize throughput. Several heuristic data mapping algorithms were proposed trying to achieve high system throughput. Most of the algorithms handle only one type of data. In a previous research, a data mapping algorithm which maps two levels of requests, i.e., urgent and non-urgent data, has been presented. However, only the number of required slots were considered in determining the order of data mapping. In this thesis, we propose an enhanced version which considers both the number of required slots and the modulation level for each mobile station. Simulation results show that, compared with previous design, the enhanced algorithm serves more urgent data with higher throughput.