臺灣博碩士論文加值系統

長期演進（Long Term Evolution；LTE）系統中基地台（eNodeB；eNB）為提供用戶(User-Equipment；UE)空中介面服務的重要角色，依據用戶需求提供服務。由於實際網路中的負載會時隨時間而變化，當用戶因重大的活動而聚集至細胞（Cell）內某個區域（Sector）內時，區域內的用戶大量增加導致Cell內各區域用戶需求及其資源分配嚴重不均的負載不平衡情形。
為因應用戶數量的改變，資源配置也需依用戶需求而適當的調整，但調整頻寬資源時容易產生細胞間干擾（Inter-Cell Interference；ICI）問題。一般常用的研究方法為部份頻率重複使用(Fractional Frequency Reuse; FFR)及軟頻率重複使用(Soft Frequency Reuse; SFR)，它們是透過限制Cell邊緣區域可用的頻寬資源來避免對鄰近的Cell造成干擾，因此對整個Cell而言，整體可利用的頻寬資源因此減少，而且頻寬資源並沒有因服務區域的用戶數不同而進行改變，當服務區域的用戶數改變時，造成資源分配不均和用戶平均傳輸量不公平。
為解決上述問題，本論文提出可調適頻率重複使用方法（Adaptive Resources Adjustment Method；ARAM），重新調整各區域的頻寬資源配置，改善因負載不平衡所造成的資源分配不均，並尋找與鄰近Cell的相鄰區域間，彼此不相干擾的可用資源改善用戶平均傳輸量及資源利用率。從模擬結果得知，本論文的方法在系統未達滿載容量前可以有效的改善用戶平均傳輸量及資源利用率。

The eNB (eNodeB) in Long Term Evolution (LTE) system plays an important role to provide the service of UE (User Equipment) requirement in air-interface. Since the traffic load is time variant in the network, when the UEs gathered into one cell’s sector due to a significant activity happened, a large number of UEs within the region increased in the cell that leads to a huge requirement of UEs and load imbalance situation due to unbalanced resource allocation.
To cope with the variance in amount of UEs, and the allocation of frequency resources also needs to be adjusted appropriately according to the UE requirement but the adjustment is prone to lead to Inter-Cell Interference (ICI) problem, Commonly used methods are Fractional Frequency Reuse (FFR) and Soft Frequency Reuse (SFR) which can avoid interference to nearby cell through restriction of frequency resources availability in their own cell’s sectors, the available resources of entire cell will be reduced and these methods will not be adjusted their frequency resources according to the different numbers of UEs in each sector, when the network topology has been changed, the allocation of frequency resources and UE average throughput are not equally distributed.
In order to resolve above problem, hereby we propose Adaptive Resources Adjustment Method (ARAM) to make adjustment the allocation of frequency resources in each sector to solve the load imbalance issue and find out the available frequency resources that no interference in neighborhood cell’s sectors to improve UE average throughput and resource utility. Based on the simulation result, UE average throughput and resources utilization can be effectively improved beforehand the system reaches full load capacity

摘要 I
Abstract II
誌謝 III
目錄 IV
圖目次 VI
表目次 IX
第一章 緒論 10
1.1 簡介 10
1.2 研究動機與目的 11
1.3章節概要 12
第二章 LTE概述 13
2.1 LTE系統簡介 13
2.1.1規格簡介 13
2.1.2傳輸架構 14
2.1.3訊框結構 16
2.1.4資源區塊 20
2.1.5 X2傳輸介面 24
2.1.6 FFR、SFR介紹 28
2.2相關研究 31
第三章 可調適頻率重複使用方法 34
3.1 問題描述 34
3.2系統基本架構 36
3.3 ARAM演算法 38
3.3.1 演算法 1 ARAM 38
3.3.1.1 初始值參數說明 41
3.3.1.2 主流程參數說明 43
3.3.1.3 潛在Cell間的同頻率干擾 45
3.3.2 演算法 2 建立各區域的可用資源清單 48
3.3.3 演算法 3 資源分配予Cell內各區域 49
第四章 系統模擬與結果 50
4.1 模擬環境 50
4.2 系統參數 54
4.3 效能評估項目與模擬結果分析 59
4.3.1 Cell 0各區域上傳傳輸量 59
4.3.2 Cell 0上傳傳輸量 64
4.3.3 Cell 0用戶平均上傳傳輸量的公平性指數 68
4.3.4 Cell 0封包丟棄率 72
4.3.5 Cell 0資源利用率 76
4.3.6 Cell 1上傳傳輸量 80
4.3.7 Cell 3上傳傳輸量 84
4.3.8系統上傳傳輸量分佈圖(Traffic Load 100%) 87
第五章 結論及未來研究 100
參考文獻 102

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