Threaded-Tree為基礎之Bluetooth Scatternet形成機制

Threaded-Tree Bluetooth Scatternet Formation

林鈺傑(Yu-Chieh Lin)

指導教授 ： 賴國華

元智大學/資訊學院/資訊工程學系/碩士(2003年)

摘要

Bluetooth是一種短距離無線通訊技術。配備Bluetooth晶片的各種裝置可在2.4G Hz的頻帶上以跳頻的方式與其他Bluetooth裝置形成一個Piconet。多個Piconets則藉由Relays連結成一個Scatternet，使不同Piconet的裝置可以透過Relays的傳遞訊息而互相通訊。 基於Bluetooth在Link層和MAC層上先天的限制，結構良好的Scatternet必須考慮到路由的效率、Master節點的通訊連結數以及Relay節點的個數等特性。針對Bluetooth Scatternet的拓樸形成，我們提出Traffic Dependent Link Formation(TDLF)來改善Bluetooth的規格在實現即時服務上的限制。藉由跳頻及分時特性，充分利用各節點的時槽，建立暫時性連線提供即時傳輸的服務，克服Piconet內中Slave節點間缺乏直接連結的缺點。另外提出Threaded-Tree Scatternet Formation(TTSF)之Bluetooth拓樸形成演算法，達到在動態環境內快速建立具良好通訊特性之Scatternet的目的。藉由設定不同的狀態交替、狀態間隔及節點種類，各節點交換所需的資訊後，可決定各自的角色，進而連接成為樹狀之拓樸。再進一步的引用TDLF機制來建立提供即時傳輸之暫時性連線，建立成一個以Threaded-Tree為基礎的Bluetooth Scatternet。 在模擬實驗中，TDLF對於標準藍芽Piconet架構的系統效能可改善將近33%，另外TTSF在Scatternet的形成速度上最大可達到26%的效能改善。

關鍵字

藍芽 ； 藍芽Scatternet ； 拓樸形成 ； 拓樸最佳化

並列摘要

Bluetooth is a short range wireless communication technique. Portable devices with Bluetooth modules embedded operate at 2.4G ISM band and communicate with each other by forming a Piconet. Multiple Piconets can then be combined to constitute a larger Scatternet and transmit data through the relay (or bridge) nodes. Within the constraints imposed by the emerging standards of Bluetooth Link layer and MAC layer, the routing efficiency, link degree of the Master node, and number of Relay nodes are the major factors need to be taken into account for a well-structured Scatternet. We propose a Traffic Dependent Link Formation (TDLF) to improve the efficiency of real-time services. By adequately employing the time slots of each node, we can construct threads for supporting real-time transmissions. Additionally, we also propose a Threaded-Tree Scatternet Formation (TTSF) algorithm to form a Scatternet in a dynamic environment with different state alternation sequences, state intervals, node types, and data synchronization. Our TTSF algorithm first builds Scatternet by connecting nodes into a tree structure, and then adopts TDLF to evolve the topology into a threaded-tree based Bluetooth Scatternet by forming threads. Simulation results demonstrate that the TDLF approach can make a 33% improvement on the system throughput compared to the standard Master/Slave model. Additionally, TTSF can make a 26% improvement on the Scatternet formation effiency.

並列關鍵字

Bluetooth ； Scatternet ； Topology Formation ； Topology Optimization

參考文獻

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