Distributed Power Control in Wireless Networks

無線網路主要的特性就是稀有的無線資源和移動裝置或無線感應器的有限電池能量。並且，一個電力控制的無線網路頻寬會隨著使用者的移動、訊號的衰減和屏蔽效應等因素而改變。因此，無線網路中無法保證所有的使用者都可以維持他們的服務品質或是訊號品質。在這個研究中，我們提出一個二階段分散式的子集合的選擇方法，用來找出一子集合的無線使用者，使得他們的服務品質可以被保證。在第一個階段，我們的方法可以找出一個基本可行的集合，然後在第二階段，再將這個基本可行的集合擴大。針對預防無資源可用的使用者，我們討論在電力領域和時間領域的衝突解決方式。經過模擬，我們可以在平均可行的連線個數、平均執行的時間上和最大等待時間等方面來檢驗我們所提方法的效能。在跨層設計這方面的研究，我們考慮無線感應式網路，因為無線感應網路能夠用來探測環境的現象，所以受到愈來愈多的重視。因為每一個無線感應裝置都有有限的電力，如何能有效的利用電力在設計無線感應網路相關協定上是相當重要的課題。在無線感應網路中，資料匯集是可以有效降低電力消耗的方法之一。在這個研究上，我們提出一個結合資料匯集跨層的方法，這個方法可以最小化電力消耗。最重要的是，我們提出來的方法是分散式的，因此很適合用於無線感應網路上。從數值分析上，我們得到一個結論，並不是所有的資料都在被送至目的地前都需要被匯集才可以達到最省電。除此之外，我們透過模擬，評估我們方法帶給網路使用期的長短。

關鍵字

電力控制；子集合選取；服務品質；連線允許控制；資料聚集；無線感應網路

並列摘要

The main characteristics of wireless networks are the scarce radio resource and the limited battery of mobile stations or wireless sensors. The capacity of a power controlled wireless network can be changing due to user's mobility, fading or shadowing effects. As a result, the quality of service (QOS) of all users may not be guaranteed in a wireless network. In this study, we propose a two-phase distributed subset selection algorithm to identify a subset of wireless users whose QOS is guaranteed. In the first phase, it finds a basic feasible set, and then it tries to expand the basic feasible set in the second phase. For starvation prevention, we discuss conflict resolution in the power domain and in the time domain. Through simulations we evaluate the performance of the proposed scheme in terms of the number of average feasible links, the average execution time and maximum of the cycle time. In the study of cross-layer design, we consider the wireless sensor networks since wireless sensor networks attract more and more attention due to being capable of monitoring the environment. Since wireless sensor nodes typically have limited energy and power, power efficiency is a main concern in designing protocols for wireless sensor networks. Data aggregation is one of the strategies that can reduce the power consumption in wireless sensor networks. In this study, we propose a distributed cross- layer algorithm with data aggregation to minimize the power consumption. Most importantly, our proposed algorithm is distributed and therefore, it is suitable for wireless sensor networks. From numerical results, we conclude that not all data packets should be aggregated before they arrive the destination nodes. In addition, we evaluate the performance of our proposed algorithm in the network lifetime.

並列關鍵字

Power Control ； subset selection ； quality of service ； connection admission control ； data aggregation ； wireless sensor networks

參考文獻

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國際替代計量

Distributed Power Control in Wireless Networks

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