基於WiMAX 802.16e與802.16j共構環境下效能提升之研究

Abstract

本研究的目的在於探討在WiMAX 802.16e 與802.16j 共構環境下之系統效能提升，我們考慮二階層式系統（Two-Layer System）以增加系統容量、提高資源使用率（Utilization）傳輸速率（Data Transmission Rate）與通話成功率（Call completion Rate）。考慮802.16j細胞完全覆蓋802.16e的細胞下，我們以速度將用戶分類為二個群組：高移動速度用戶由涵蓋範圍較大的802.16e基地台服務，而移動速度較慢的用戶如行人則由802.16j基地台服務，藉此減少換手（Handoff）次數以避免其產生之種種問題。Overflow策略、Channel Reservation策略以及混合式策略（Hybrid Method）亦對提高系統效能。 本論文的貢獻為： 1． 提出在WiMAX 802.16e 與802.16j 共構環境下產生系統最大容量最之頻率分配。 2． Overflow策略、Channel Reservation策略能有效提高系統效能如與通話成功率（Call completion rate）與資源使用率（Utilization）。 3． 提出混合式策略（Hybrid Method）以期效能有更進一步的改善。

The objective of this thesis is to study the performance improvement under the co-existence of 802.16e and 802.16j WiMAX systems. The two-layered architecture is adapted to investigate the performance measurements including the system capacity, call successful rate, and channel utilization. Under the environment of full coverage of 802.16j cells in 802.16e, the cells of 802.16e cover larger area and designed to serve high speed users. On the other hand, cells of 802.18j cover smaller areas are designed to server pedestrian and low speed user so as to reduce the handover failure rate. The overflow, channel reservation, and the hybrid algorithms are also studied for further improvement. Our main contributions are as follow 1. Proposed the frequency assignment under co-existence of 802.16j and 802.16e following constrain of 802.16 specifications to achieve the maximum capacity. The frequency pattern and adaptive modulation are also taken into consideration. 2. The overflow and channel reservation algorithms are studied to improve the performance including call successful rate, and channel utilization. 3. The hybrid algorithm is proposed for further improvement.