毫米波無線個人通訊網路適於群播應用之排程演算法

Abstract

由於近年來對於高速多媒體傳輸的要求變得很受歡迎，IEEE 802.15.3c訂定了媒體存取控制與實體層的標準。其實體層的特性包含了使用頻帶在60GHz ISM上和波束成形技術，60GHz ISM 造成了較高的訊號路徑衰退，波速成形技術則是增加了空間重複利用性。從現今應用的角度來看，多媒體資料傳輸較適合以群播方式傳輸。從 Shannon 的頻寛理論來看，我們可以發現群播資料流的容量和接收者的數目多寡、傳輸者和最遠接收者的距離、傳輸者的波束角度大小有關。而且，對於每一個群播資料流的接收者選擇方式將會影響空間的重複利用性。每個群播資料流有指數種單一分群方式和可排程之接收者分群集合。我們的目標是針對群播資料流提出一個有效的連線樣本選擇方式並且結合所提出的公平的排程演算法達到最大化網路效能且不失去公平性。模擬結果顯示提出的連線樣本方法所選擇的連線樣本在效能上比原本的連線樣本和全部都拆成單播資料流連線樣本更好，且其效能可近似區域最佳解。和REX 排程演算法相比，所提出的排程演算法有較好的效能但也失去一些公平性。

The high speed multimedia transmission applications had been become popular in recent year, the IEEE 802.15.3c task group had been compose the media access control (MAC) and physical layer (PHY) standard. The physical characteristics include adopting frequency at 60GHz ISM band and beamforming technique which respectively causes high path loss and increases the spatial reusability. In the recent application view, the operation of multimedia data transmission prefers adopt multicast transmission scheme. With the observation of Shannon capacity, we can find out the capacity of a multicast flow is highly correlated with number of receivers (links), distance between sender and receivers and beamwidth of the flow. Also, the link pattern selection of each multicast flow would affect the spatial reusability. Each multicast flow has exponential number of link flow patterns and schedulable link flows set. Our objective is to propose an efficient link pattern selection scheme for each multicast flow and joint the fair scheduling algorithm to maximize the system throughput without losing the fairness. The simulation results show that the proposed joint link pattern selection and flow scheduling scheme is better than only unicast link pattern and original link pattern, and the performance approximate to local optimal link pattern selection scheme in throughput. Compare with REX scheduler, the proposed scheduling scheme is better in throughput but with minor loss in fairness.