於無線感測網路中利用網路編碼達成可靠性傳輸

無線感測網路在現今許多領域被廣泛地運用，例如環境監測、健康照護系統、交通控制及野外生態調查。感測節點中如能源、計算能力及資料儲存空間都屬於有限的資源。再加上無線網路中訊號強度的劇變，電波干擾等因素影響。因此本篇論文的重點在於，如何在一個無線感測網路中提供可靠性的資料傳輸，同時考慮到網路存活的時間長短，這也是當今一個重要且富有挑戰性的議題。一般來說，傳統上有多種端對端提供可靠性傳輸的作法，例如自動請求回覆(ARQ)、多徑傳輸(Multipath Forwarding)及前向糾錯(FEC)。但是這種傳統端對端固定傳輸路徑的作法，它們的網路負擔跟效能往往會被傳輸路徑中一兩個品質很差的節點或是鏈接所限制。造成環境很差的情況下效能會快速下降、太多的網路負荷及需要花很多功夫在維持路徑通暢。因此我們認為這種作法無法在無線網路中對環境改變作快速又有效的自我調適。為了解決上述的議題，我們這篇論文主要希望提出在無線感測網路中提供一個有效率的可靠性資料傳輸的方法。換句話說，我們的目的除了保證資料的安全送達外，也希望對網路的負擔愈小愈好，並且我們的方法還要能夠針對網路狀況的改變作適度的自我調適。我們提出的作法是一個以高度為基礎的資料集中式無線感測網路架構。此外，我們會在我們的作法中加入網路編碼的技巧，導出一個數學模型作我們的理論基礎來逐站(hop-by-hop)保證我們的資料安全地被送到目的地。最後，藉由一個我們所提出叫作”Lazy Re-computation”的想法，可以幫助我們的方法更快速地對網路狀況的變動作調整。我們用ns2作為我們的模擬平台來驗證我們的方法。實驗結果證實我們的作法在不同的環境設定情況下，相較於過去的作法都能有較好的表現。

關鍵字

Wireless Sensor Network ； Network Coding ； Reliable Transmission

並列摘要

Wireless sensor network(WSN) has been widely used in many applications, e.g.,environment and habitat monitoring, health-care application, traffic control, or wild ecological survey. Due to scarce resources like energy, computational capability and storage space in a sensor node and rapid change in wireless link characteristics such as signal strength, interference, and multipath propagation, how to provide a reliable data transmission in WSN while prolonging the network lifetime as long as possible is an important and challenging issue, which is the focus of this work. In general, there are several end-to-end approaches, e.g., automatic repeat request, multipath routing and forward error correction coding, used for provision of reliable data transfer in a wireless sensor network. We note that the overhead and performance of such end-to-end fixed-routing approaches are often dominated by some poor-quality links or nodes on the path. This could result in quick degradation in performance, adding too much redundancy data, spending many efforts in route maintenance. That is, these traditional approaches are not able to quickly and properly react in this multihop wireless environment. To cope with the above issues, in this work we would like to propose an efficient reliable data transfer scheme for a wireless sensor network. In other words, the goal of our scheme is to guarantee the reliability in data transmission, to add redundancy data as less as possible, and to self-adapt to the time-varying network environment. Hence, we propose a height-based data-centric routing structure in a WSN. In addition, by applying the network coding, we derive an analytic model to guarantee an end-to-end reliable data transfer in a hop-by-hop manner. At last, with the help of a lazy re-computation scheme, our protocol is able to quickly react to the fluctuation of wireless network environment. We use the simulation in ns2 to evaluate our approach and the results show that, compared with existing reliable data transfer schemes, our approach is able to perform substantially better in various experiment-settings.

並列關鍵字

無線感測網路；網路編碼；可靠性傳輸

參考文獻

”Network Information Flow”. in IEEE Transactions on Information Theory, IT-

[2] Chou, P.A. and Wu, Y. and Jain, K. ”Practical network coding”. in Allerton

Conference on Communication, Control, and Computing, 2003

[3] Li, S.Y.R.Y. and Cai, R.W.N. ”Linear network coding”. in IEEE Transactions

on Information Theory, 2003

國際替代計量

於無線感測網路中利用網路編碼達成可靠性傳輸

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