具有跳頻機制之無線感測器網路媒體存取控制協定設計

Design of Medium Access Control Protocol with Frequency Hopping for Wireless Sensor Networks

王建昌(Chien-Chang Wang)

指導教授 ： 曾傳蘆 博士

國立臺北科技大學/電資學院/電機工程系研究所/碩士(2011年)

摘要

為了使感測器網路在低功率通訊時擁有更高的可靠性，及節點在同一時間通訊而不受其他網路的干擾，本論文提出一具有跳頻重傳機制之媒體存取控制，且適用於無線感測器網路野外生態監測的媒體存取控制(F-MAC)協定。
由於F-MAC協定在資料傳輸過程中，當發生資料遺失而進行補傳時，只透過多重路徑的方式將資料回傳，並未考慮資料是否回傳成功。有鑑於此，本論文修改F-MAC之同步流程並設計一可靠的資料傳輸機制。本機制參考了藍牙所使用之適應性跳頻技術，並考慮同樣為2.4 GHz其他網路之間的干擾，藉此提出一個簡化藍牙之跳頻機制。透過節點在傳輸資料時，判斷接收端未收到傳送端回覆的ACK筆數，作為產生跳頻序列的輸入，對應到一個由雜湊方式所產生跳頻序列表，以完成跳頻的動作，來提高抗干擾及通訊碰撞問題，讓此協定有更好的效率。
最後，本論文透過實作並分析測試本機制之封包遺失率、網路流量及跳頻效能評估等性能指標，由結果發現其平均封包接收率較單一頻道佳。除此之外，本論文所設計的跳頻重傳機制亦比原先F-MAC補傳資料之傳送成功率高出2.09 %，未來將應用於野外生態監測系統上，以提高資料傳輸可靠性。

關鍵字

無線感測器網路 ； 跳頻 ； 媒體存取控制

並列摘要

This thesis presents a retransmission mechanism with frequency-hopping media access control to achieve the goal of higher reliability of low-power consumption sensor networks without interference in communication from other networks. This mechanism can also be applied to the media access control protocol (e.g. F-MAC) for ecological monitoring.
In the F-MAC protocol, lost data can be retransmitted by the multi-path mechanism, but no mechanism exists to confirm a successful transmission. Therefore, the thesis proposes a modified synchronization mechanism for F-MAC and a more reliable data transmission method . Based on the adaptive frequency hopping (AFH) of the Bluetooth technology, a simplified Bluetooth frequency-hopping mechanism is developed, while taking the interference from other networks that also use the 2.4 GHz frequency band to transmit data into account. Before the transmission, a sender (node) determines the amount of data that will be transmitted to a receiver (node) and the sequence number of the data. The receiver will immediately reply an acknowledgement (ACK) message to the sender to confirm that the data which has been received. When data is lost during transmission, the sender records the number of missing ACK messages. This number will serve as the frequency hopping input that corresponds to the frequency hopping sequence table generated by the hash method to complete the frequency-hopping action.
Finally, the experimental results show that the average package receiving rate using the proposed mechanism is higher than the rate using a single channel to transmit data after packet loss, network traffic and the performance of frequency hopping are examined. Besides, the successful transmission rate generated by the frequency-hopping retransmission mechanism is 2.09 % higher than the rate using the retransmission mechanism built in the F-MAC. The proposed mechanism will be applied to ecological monitoring systems in the future to improve the data transmission reliability.

並列關鍵字

Wireless Sensor Network ； Frequency Hopping ； Medium Access Control

參考文獻

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