近來，IEEE 802.16j的工作小組專注於制定一個藉由中繼技術來延伸傳輸範圍、延伸覆蓋範圍，以及提升網路效能的新網路架構。本論文提出一個適用於IEEE 802.16j多躍中繼網路(Multi-hop Relay Network, MR Network)的路徑選擇機制，此機制除了考量無線鏈結的Spectral Efficiency，並加入無線鏈結的負載量為路徑評估因子，目的是希望選擇出來的路徑是具有較佳的Link Spectral Efficiency，更希望盡可能將擁塞的無線鏈結上的流量分散到其他可能的無線鏈結上以提升網路效能。從實驗結果顯示，相較於之前的相關研究，本論文所提出的路徑選擇機制不但有較佳的Throughput，並可減少Map Overhead。

In the IEEE 802.16j multi-hop relay (MR) network, the design of an effective path selection scheme is an important issue for throughput gain and overhead reduction. This paper proposes a new metric, called SEL, to evaluate the relay path and thereby determine the appropriate one among the possible paths. SEL mainly considers both link spectral efficiency and link load. Based on SEL, a comprising function is also developed to formulate the path cost to select the appropriate relay path. As confirmed by the performance evaluation, the proposed path selection scheme with SEL consideration significantly outperforms the existing path selection scheme in network throughput and map overhead.

1 Introduction 1
2 Preliminaries 5
  2.1 Overview of IEEE 802.16j 5
3 Problem Statements 8
  3.1 PSP in the IEEE 802.16j MR Network 8
  3.2 Link Overloading in PSP 12
4 Proposed Path Selection Scheme 14
  4.1 SEL: Spectral Efficiency and Load-aware Metric 14
  4.2 Link Spectral Efficiency 15
  4.3 Link Load 18
  4.4 Path Cost Calculation 19
  4.5 Routing Information Report and Notification 21
5 Performance Evaluations 22
  5.1 Simulation Setup 22
  5.2 Simulation Results 24
6 Conclusions 29
Bibliography 30

List of Figures
Figure 1.1 The radio links in an IEEE 802.16j MR network 2
Figure 2.1 Transparent RS and non-transparent RS 6
Figure 2.2 Transparent relay frame structure 7
Figure 2.3 A 3-sector system and its corresponding 3-segment frame structure 7
Figure 3.1 The network entry procedure 10
Figure 3.2 Link overloading problem 12
Figure 5.1 Network throughput of various schemes for di®erent scenarios 25
Figure 5.2 Map overhead generated by various schemes for di®erent scenarios 27
Figure 5.3 Enhancement of the SEL-relaying scheme 28

List of Tables
Table 5.1 System-level simulation parameters 22

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