在能量擷取網路中可靠性廣播傳輸機制之設計與分析

Abstract

在本篇論文中，我們探討在能量擷取網路環境中的可靠性廣播機制。透過能量擷取裝置，通訊設備可以從環境中獲取能量，例如太陽能，動能，熱能等。在傳統的網路中，資料在傳輸過程中可能因為傳輸媒介的可靠度不佳，或外在因素的干擾而遭到破壞，造成傳輸失敗。而在能量擷取網路中， 可靠傳輸將面臨另一項挑戰：當電池的能量用盡時，通訊設備將無法接收或傳輸資料。綜合以上考量，我們採用糾刪編碼(Erasure Coding)來達成可靠性的廣播傳輸，此外，提出能量感知接收機制及提前終止接收機制來提升能量的使用效率。同時，我們也提出了數學模型來分析效能。從理論結果發現，調整不同的廣播週期，傳輸量和可靠性之間存在取捨關係。針對不同種類的資料，我們提出了三種廣播方針來決定廣播週期。第一是傳輸量優先方針， 目的是最大化整體的傳輸量。第二是可靠性優先方針，目的是確保每個接收器能成功接受。最後是折衷方針，也就是兼顧傳輸量和可靠性的傳輸方法。最後，我們利用程式模擬來驗證數學分析，我們發現分析結果和模擬結果相符合，並且也可以看出使用能量感知接收及提前終止接收機制的效能明顯優於單純使用糾刪編碼的傳輸。

In this paper, we study the reliable broadcast transmission in energy harvesting networks. It is assumed that the base station has some broadcast data to multiple energy harvesting devices. The transmission errors may occur by noise or other impairments during transmission. The technique of forward error correction (FEC) is widely used for controlling errors. In additional to transmission error, the other main challenge posed to a reliable transmission in energy harvesting networks: energy deficiency. It refers that the energy harvesting node cannot work when its battery is exhausted. To deal with this problem, we propose the energy-aware receiving scheme and early-termination scheme. Combining the above issues, we take both transmission error and energy deficiency into account and propose system design and the theoretical analysis for reliable broadcast transmissions. We also investigate the trade-off between reliability and throughput in different broadcast period. For different requirements, we propose the reliability-first policy, throughput-first policy and eclectic policy to determine the broadcast period. The simulation results are in line with the theoretical values. It also indicates that proposed schemes can dramatically improve the performance of broadcast transmission.