在正交分頻工多工微型基地台網路中,與大型基地台之間的跨層級干擾和鄰近微型基地台共層級干擾往往會影響整體環境的表現。在上行鏈路中,當大型基地台用戶鄰近微型基地台時, 會對使用者造成極大的干擾,本文將大型基地台用戶換手到微型基地台以解決跨層級干擾之問題。我們把換手機制分成兩部分:通道選擇和功率分配。在通道選擇中,提出不同的考量方式:最大化容量和最小干擾量,並設計一兼俱此兩種方法優勢之混合方式。模擬結果顯示,混合方式選出通道可以達到最大的通道容量。在功率分配方面,我們討論兩種傳送功率的方法,一為貪婪方式, 二為平衡訊號 ––干擾 ––雜訊比值方式,結果顯示,平衡訊號干擾雜訊比值的方式可以較低功率來達到對雙方使用者均衡通道容量。整體而言,本文提出的方法將有助於提升換手機制處理跨層級與共層級干擾問題的表現。 本文最後針對此類問題與其解決方法提出若干深入的討論與可行之建議。

In the OFDMA femtocell network, the cross-layer interference between macrocell and femtocell and co-layer interference between neighboring femtocells can deteriorate the overall affect system performance. In uplink transmissions, when a macrocell user is close to the femtocell base station, it can cause severe interference. In this paper, we propose an algorithm that led the MUE to select a sub-channel in femtocell to eliminate the cross=layer and co-layer interference. We divide the handover procedure into two parts: subchannel selection and power allocation process. In the subchannel selection, we propose three selection schemes: The maximum capacity selection, minimum interference selection and hybrid SINR and interference selection. In the power allocation we discuss greedy power allocation and balanced SINRs allocation schemes. According to the simulation results, we observed that the hybrid selection scheme can achieve higher channel capacity. This observations reveals that the balanced SINRs allocation scheme can achieve balanced SINR among users using less transmission power. To sum up, the propose methods can improve overall system performance thanks to the handover mechanism by eliminiating the cross-layer interference and co-layer interference. Some suggestions for possible research topics in the future are provided in the end of the thesis.

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