適用於分散式存取系統且具有強健性的劃分演算法

Abstract

在無線通訊上,分散式媒介允許控制(Medium Access Control)協訂常用於傳送資料。我們考量輸出以及當錯誤發生時的穩定性來設計我們的協定為了解決輸出過低的問題，我們參考兩種不同的媒介允許控制協定,slotted Aloha和劃分演算法(Splitting algorithm)為了改善這兩者的缺點我們提出一種輸出和劃分樹狀演算法的輸出差不多且在對抗錯誤傳輸時更強健的協定。和劃分樹狀演算法不同得是我們的協定更適用於較分散式的系統。由於在我們的協定中我們假設每個使用者都知道現在有多個使用者想要傳送所以我們稱呼我們的協定為 N以知的劃分演算法。這個方法的輸出約0.45。而強健在無線通訊上另一個重要問題。此外我們針對錯誤傳輸列舉了一些極端的情形並且去討論我們的方法對錯誤傳輸的容忍度。並且模擬在不同的錯誤率下的輸出。根據模擬結果我們可得知在錯誤率很小的情形我們的輸出約等於無錯誤時的輸出減去錯誤率

Distributed MAC protocols have long been used in the existing wireless communications for data transfer. In devising our protocol, both throughput and robustness against error-prone transmission are considered. In order to improve the throughput, our proposed protocol is based on two kinds of medium access control protocol, Slotted Aloha and splitting algorithm. In doing so, our proposed protocol supplements the drawbacks of these two protocols by achieving the throughput as high as the splitting tree algorithm whereas sustaining the robustness against the error-prone transmission. Besides, unlike the splitting tree algorithm, our protocol can be rendered into the highly distributed system. Due to the assumption that the number of active or so-called backlogged users needs to be known in our protocol a priori, we call it as “N is known splitting algorithm”. By analysis, we show that the maximum throughput of our proposed protocol is around 0.45. In addition, we enumerate certain critical cases and discuss the capability of our method against the erroneous transmission. We simulate our method in different error rate and verify their throughputs. According to our simulation results, we can find that our throughput of an error rate is similar to the throughput of no error minus the error rate when the error rate is small enough.