資料無線下載之負載感測天線傳送功率控制

Abstract

在無線蜂巢式網路中，基地台的涵蓋範圍通常會與鄰近的基地台重疊，以提供邊界的使用者能成功通訊的機會，但是卻因此也增加了基地台之間的互相干擾程度，而降低了使用者的資料傳輸速率。所以我們利用基地台天線傳送功率控制，來減輕使用者受到鄰近基地台的干擾，已達到增進使用者資料傳輸效率的目的。我們假設基地台能夠提供兩種分別為高及低的傳輸功率，並藉由感測每一個細胞格的負載狀況，將這兩種傳輸功率適當的分配給每一個基地台。在我們的方法中，是盡量將負載較高的細胞格基地台設定為高傳輸功率，而將其鄰近負載較低的細胞格基地台設定為低傳輸功率。由程式模擬的結果顯示，這樣的方法可以讓使用者傳輸資料的延遲，有不錯的改善。再來我們考慮細胞格內的負載，並不會一直如預期的均勻分布在細胞格內，所以考慮更進階的方法，來克服不均勻的傳輸負載的情況。在進階的方法中，能夠利用細胞格的負載偏向方位，進而設定其附近的基地台天線傳輸功率。程式模擬的結果顯示，在時間上以及空間上的不均勻傳輸負載，我們的方法都能明顯的減少使用者所需等待的延遲時間。We propose power level control schemes to improve the forward link data throughput of mobile users in cell edges where inter-cell interference is significant. We assume that the antenna power of base station (BS) can be adjusted to full power (high power level), reduced power (low power level), and no power. We then propose algorithms by which the cell with the highest loading is first chosen to transmit at high power level while some of its neighboring cells with lighter loading are chosen to transmit at low power level. Such a procedure is repeated until each BS antenna is set to a proper power level. We further assume that the information of sectorized loading is available and then modify the proposed algorithms taking into account the information. Based on numerical data all obtained from simulations, we study the performance of the proportional fair scheduling under proposed power level control schemes. Results show that our schemes are able to achieve more favorable delay-throughput characteristics, less interference holes, and traffic hot-spot relief.