近年來，高速無線連線的需求爆炸性的增加，使用者對於頻寬的需求也逐漸提高，在無線資源有限的情況下，使用者對於頻寬的大量需求容易導致蜂巢式無線網路的基地台擁塞，為了卸載這些壅塞基地台的負載量，異質性網路成為無線通訊重要的研究的領域之一。異質性網路意指在現存的蜂巢式網路架構下，佈建一些較低功率的基地台，使之能夠分流壅塞基地台的負載量為了分析基地台分佈的拓樸對負載分流的影響，多數文獻使用隨機幾何來建構不同層級的基地台，為了分析簡易起見，相關文獻多忽略用戶移動過程造成的基地台換手問題，但現實生活中，使用者並非保持靜止不動，因此本論文將特別針對使用者的移動性，探討基地台佈建於異質性網路下的效能，並且對用戶移動時所產生的換手事件做近一步的數值分析，進而了解換手對移動用戶之連線品質的影響。除此之外，針對移動速率高的用戶，在考量到資源分配以及基地台之間的干擾問題之下，本論文提出三種機制改善整體的網路效能，根據模擬結果可明顯看出系統效能的改善。

In the current wireless cellular network, the massive bandwidth demands from users causes traffic congestions in the network that can dramatically degrade the service provisioning to mobile users. To offload congested base stations (BSs), next-generation cellular network will change from the homogeneous setting to the heterogeneous configuration, where lower-power BSs will be deployed in existing cellular infrastructure, forming the heterogeneous cellular network (HCN). With such a fundamental change of the network infrastructure, maintaining seamless service provisioning in HCN becomes challenging. In this thesis, we theoretically analyze the handoff probability in the two-tier HCN by developing an analytical model based on stochastic geometry. The developed theoretical model captures the randomness of BS locations and the average BS load that are both crucial to the handoff probability. The obtained handoff probability is then used to characterize the coverage probability of HCN considering user mobility. To improve the mobility support in HCN, we propose three mechanisms for different purposes: 1) reducing the handoff probability, 2) mitigating resource shortage, and 3) enhancing traffic offloading. We present numerical results to validate the analysis accuracy and demonstrate the performance of the proposed mechanisms in enhancing service provisioning HCN.

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