LTE-Advanced利用毫微微基地台載波聚集消除雜訊制

Abstract

因為無線網路的需求大量增加，不論是在網路流量和延遲方面的要求都越來越高。所以在第四代行動通訊系統，對網路品質的要求就變得相當高，為了達到這麼高的要求，基地台就部建得比較密集，以提升接收端地接收能量強度。但是在一些特殊的地方，像是建築物之內，或是距離基地台比較遠的地方，接收能量強度都會受到很大的影響，這樣就會拉低整個系統的效能。另外，有的時候可能使用者較多，基地台能提供的流量有限，使用者的傳送速度就會受影響。 在這種情況下，毫微微蜂巢式基地台就會被使用。毫微微蜂巢式基地台是由網路的使用者自行部建的，所以毫微微基地台的分布是部經過規劃的。因此，毫微微基地台之間相互干擾的情況有可能會非常嚴眾，尤其是在毫微微基地台比較密集的地方，這樣部建密集的毫微微基地台所提升的網路效能濟會被限制住。另外，不只有毫微微基地台之間的干擾，毫微微基地台也會對一般基地台造成干擾。所以如何有效控管這些基地台之間的互相干擾是非常重要的。 在這篇論文中，我們提出了在LTE-Avanced的通訊系統中，利用carrier aggregation的方法，依照通信系統中的狀況進行頻道的配置，來避免基地台之間的互相干擾。

Due to the increasing demand of capacity in wireless cellular networks, the small cells such as pico and femto cells become more popular to enjoy a spatial reuse gain, and thus cells with different sizes are expected to coexist in a complex manner. In such a heterogeneous environment, the role of interference management (IM) becomes more importance, but technical challenges also increase, since the number of cell-edge users, suffering from severe interference from the neighboring cells, will naturally grow. In the thesis, we consider the condition that the users are on the edge of the cell. Because of the long distance from the users to the base station, the femtocell are placed densely to enhance the capacity. However the interference between femtocell may become very severe, and the capacity of the users is influenced dramatically. In our observation, the interference can be greatly decreased by dividing the frequency band into subbands and correctly allocate the subbands to the femtocells. The capacity can be improved when the interference is lower. In order to overcome the interference between the femtocells we proposed an algorithm to allocate the subbands to the femtocells. In the result, we show that when the place far from base station and with many femtocell the total capacity can be improved by our proposed algorithm.