[[alternative]]Designing User Location Tracking Strategies in Personal Mobile Communication Networks

計畫編號：NSC92-2213-E032-011研究期間：200308~200407研究經費：487,000[[sponsorship]]行政院國家科學委員

Efficient Cache Invalidation in Mobile Environments

[[abstract]]In a mobile environment, caching data items at the mobile clients is important as it reduces the data access time and bandwidth utilization. While caching is desirable, it may cause data inconsistency between the server and the mobile clients if their communication is disconnected for a period of time. To ensure information coherence between the source items and their cached items, the server can broadcast invalidation reports to the mobile clients who then use the reports to update the cached data items. Cache invalidation is indeed an effective approach to maintaining such data coherence. This paper presents a new cache invalidation strategy which is shown through experimental evaluation to maintain data consistency between the server and mobile clients in a more efficient way than existing invalidation strategies.[[notice]]補正完畢[[incitationindex]]E

[[alternative]]The Design of Advanced Value Predictors

計畫編號：NSC90-2213-E032-019研究期間：200108~200207研究經費：357,000[[sponsorship]]行政院國家科學委員

[[alternative]]The Design of Cache Invalidation Schemes in Mobile Computing Environments

計畫編號：NSC91-2213-E032-013研究期間：200208~200307研究經費：440,000[[sponsorship]]行政院國家科學委員

[[alternative]]Design of Fault-Tolerant Routing and Security Protocols in Sensor Networks

計畫編號：NSC93-2213-E032-032研究期間：200408~200507研究經費：631,000[[abstract]]近年來，無線網路技術的研發進展極為迅速，相關應用日益普遍，感測器網路便是 其中之一。有鑒於感測器網路在未來的應用發展，前景熱絡可期，我?計畫運用以往的 研究成果及心得，從兩個方向探索，為增進感測器網路的效能而努力。我?的研究目標 包括：一﹑設計一個可以容錯並且突破現有效率的感測器網路路由協定，以提升網路之 資料彙集速度：我?構想在設計感測器網路路由協定之際，帶入超立方體拓樸之特性， 利用一定之演算步驟，先行確認感測器節點如何依距離構成超立方體拓樸，然後經由類 似超立方體傳輸樹進行資料彙集，並在感測器節點發生故障或死亡時，藉由容錯傳輸樹 或不完全超立方體的方式，加速達成資料彙集的目的。二﹑為強化感測器網路的資訊安 全，本計畫擬將「多重路徑路由」融入所預計研發、以超立方體為基礎之感測器網路路 由，將資料拆開經由不同路徑送至目的端後，再重新組合，以降低資料被劫的危險。此 外亦將深入研究感測器網路之認證與加密兩項議題，參考文獻上既有之無線網路認證協 定與加密協定，經適當調整改進，設計出一套便利可行且適用於具耗電低、便宜特性之 感測器網路的安全協定，以維護感測器網路中資料傳輸的安全。[[sponsorship]]行政院國家科學委員

Employing Variable Cross-Reference Prediction and Iterative Dispatch to Raise Dynamic Branch Prediction Accuracy

[[abstract]]To improve branch prediction accuracy for the two-level adaptive branch predictor, two schemes dealing respectively with the prediction and dispatch parts, are presented in this paper. The proposed VCR prediction scheme is able to achieve desirable prediction accuracy, with reasonably low time complexity and no extra hardware cost, by variably cross-referring traces in the PHT to make predictions. The Iterative dispatch approach utilizes the PHT history to do dispatching for an additional layer of pattern history which helps providing more information for making better predictions. To attain desirable prediction accuracy at reduced cost, a combined predictor formed by the proposed VCR scheme and the optimal PPM algorithm is also considered. Extensive trace-driven simulation runs have been conducted to evaluate the performance of our proposed schemes and other predictors. As the results indicate, our proposed schemes compare favorably in most of the situations in terms of prediction accuracy.[[notice]]補正完畢[[incitationindex]]E

[[alternative]]Research on Balancing Traffic to Enhance Performance in Meshes

計畫編號：NSC89-2213-E032-039研究期間：200008~200107研究經費：401,000[[sponsorship]]行政院國家科學委員

Dynamic channel selection: an efficient strategy for balancing traffic in meshes

[[abstract]]This paper uses the idea of dynamic channel selection to balance traffic in a mesh network. The key point is to maintain the history of channel utilisation in each node. Based on the recorded information, the node router can predict the current load distribution and route packets through less trafficked channels to avoid congestion. To fit different routing characteristics, three dynamic channel selection policies, DCS-I, DCS-II and DCS-III, are presented. Experimental results show that when network traffic gets heavy, DCS-II and DCS-III yield constantly better throughput, lower communication latency and more even buffer utilisation – pinpointing the important link between balanced network traffic and desirable performance.[[notice]]補正完

[[alternative]]Wireless Optical Network Design(III)

計畫編號：NSC95-2745-E032-001-URD研究期間：200608~200707研究經費：834,000[[sponsorship]]行政院國家科學委員

[[alternative]]Designing Complete Key Distribution and Node Revocation Schemes to Enhance Communication Security of Wireless Sensor Networks

計畫編號：NSC97-2221-E032-018研究期間：200808~200907研究經費：485,000[[sponsorship]]行政院國家科學委員