光徑是一種單向的節點到節點的全光式波段，主要優點是光徑所經過的中繼節
點也能透過光徑上傳和下載資料，因此在流量疏導上提供了更大的彈性。 流量疏導
技術能夠允許多個小流量的連線需求透過一個高速的通訊通道傳輸，藉此提升頻譜
使用率。 本博士論文將分別研究使用光波分割多工技術的光徑網路下的靜態和動態
流量疏導問題。
首先，我們研究使用光波分割多工技術的光徑網路下的靜態流量疏導問題， 我
們的目標是最大化網路的流通量。我們提出了一個先進的啟發式演算法能夠根據光
徑的有效頻寬使用率來挑選承載連線需求的光徑。 實驗結果顯示我們所提出的演算
法相較先前文獻的演算法有更高的網路的流通量。
接著， 我們研究使用光波分割多工技術的光徑網路下的動態流量疏導問題。 在
以往的研究中，已有數種針對光徑網路下的動態流量疏導問題所提出的輔助圖模型。
我們發現這些輔助圖模型都存在至少一個以上無法反映光徑特性的缺陷。我們著眼
於改善這些舊有輔助圖的缺陷，提出一個能夠完整反映光徑特性的全新的輔助圖模
型。藉由所提出的輔助圖模型，我們設計了兩個有效的動態流量疏導演算法。實驗
結果顯示我們所提出的輔助圖模型和動態流量疏導演算法相較先前文獻的輔助圖和
演算法有更低的連線阻擋率。
最後， 我們研究使用光波分割多工技術的光徑網路下的動態群播流量疏導問題，
研究目標是降低連線阻擋率。 我們提出一個輔助圖以協助進行光徑網路下的繞徑與
流量疏導。 藉由所提出的輔助圖模型， 我們提出了兩個有效的動態群播流量疏導演
算法。實驗結果顯示我們所提出動態群播流量疏導演算法相較先前文獻的動態群播
流量疏導演算法有更低的連線阻擋率。

A light trail in a wavelength-division multiplexing (WDM) optical network is an optical communication channel that allows intermediate nodes to access the channel providing the flexibility for multiplexing traffic of multiple connections into the optical communication channel at intermediate nodes. Traffic grooming technique is able to multiplex multiple low-rate connections into a single high-speed communication channel in order to increase channel utilization in optical WDM networks. This dissertation studies static and dynamic traffic grooming problems in light-trail optical WDM mesh networks.
First of all, given a set of traffic demands in the network, we study the problem of designing a set of light trails to accommodate as much traffic as possible. We propose a novel heuristic algorithm to select a set of light trails based on effective bandwidth utilization. The proposed heuristic algorithm is shown to yield a high throughput ratio via simulation.
Next, we study the dynamic unicast traffic grooming problem that deals with dynamically arriving and departing connection requests in light-trail optical WDM mesh networks. In the literature, several auxiliary graph models have been developed for traffic grooming in light-trail optical WDM mesh networks. These auxiliary graph models have one or more drawbacks that do not fully reflect the characteristics of a light trail. We develop a novel auxiliary graph model that has none of these drawbacks and can reflect all the characteristics of a light trail. Based on this auxiliary graph model, we propose two effective dynamic unicast traffic grooming algorithms. The proposed dynamic traffic grooming algorithms are shown to yield low request blocking ratios via simulation.
Finally, we study the problem of dynamic multicast traffic grooming in light-trail WDM optical networks. Our objective is to reduce blocking ratio. We propose an auxiliary graph model for light-trail WDM optical networks that can be used for routing and traffic grooming purposes. Based on the auxiliary graph model, two dynamic multicast traffic grooming algorithms are studied. Compared with existing algorithms in the literature, the
two algorithms yield significantly better performance.

摘要 i
ABSTRACT ii
致謝 iii
CONTENTS iv
LIST OF TABLES vii
LIST OF FIGURES viii
1 Introduction 1
1.1 Optical WDM Mesh Networks 1
1.2 Light Trail Architecture 1
1.3 Traffic Grooming in Light trail Optical WDM Networks 3
1.3.1 Static Traffic Grooming Problem 4
1.3.2 Dynamic Traffic Grooming Problem 4
1.4 Research Topics and Proposed Approaches 5
1.5 Dissertation Organization 6
2 Light Trail Design with Traffic Grooming In Light-trail Optical WDM Networks 8
2.1 Background Information 8
2.2 The Light Trail Design Problem 9
2.3 Heuristic Algorithm 11
2.3.1 Select Light Trails Using a Greedy Procedure 11
2.3.2 Select Light Trails Using an Auxiliary Graph 12
2.3.3 Computational Complexity 14
2.4 Performance Study 14
2.4.1 Comparison of Throughput Ratios 16
2.4.2 Comparison of Bandwidth Blocking Ratios 17
2.5 Chapter Summary 20
3 Dynamic Traffic Grooming in Light-trail Optical WDM Mesh Networks 21
3.1 Background Information 21
3.2 Auxiliary Graph Model 22
3.2.1 Vertices and Edges 23
3.2.2 Representation of a Light Trail and Channel Access for Intermediate Nodes 24
3.2.3 Multi-hop Grooming 26
3.2.4 Reflecting the Total Cost for the Drop-and-continue Property 26
3.3 Dynamic Traffic Grooming Algorithms 28
3.3.1 Assignment of Edge Weights for the Bw‑Tx/Rx Algorithm 28
3.3.2 Assignment of Edge Weights for the O/E/O Algorithm 29
3.3.3 General steps of the Algorithms 30
3.3.4 Computational Complexity 31
3.4 Performance Study 31
3.4.1 Comparison of Request Blocking Ratios 33
3.4.2 Comparison of Average Numbers of Light Trails per Connection Request 38
3.4.3 Comparison of Wasted‑bandwidth Utilization Factors 42
3.4.4 Effects of Different Hop Length Limits 46
3.5 Chapter Summary 50
4 Dynamic Multicast Traffic Grooming in Light-trail Optical WDM Mesh Networks 51
4.1 Background Information 51
4.2 Auxiliary Graph Model 52
4.2.1 Vertices and Edges 54
4.2.2 Generating and Updating the Auxiliary Graph 55
4.2.3 Reflecting the Total Cost for Multiplexing Traffic into a Light trail 55
4.3 Dynamic Multicast Traffic Grooming Algorithms 56
4.3.1 Assignment of Edge Weights 56
4.3.2 Tree Branch Selection Methods 57
4.3.3 The Two Dynamic Multicast Grooming Algorithms 59
4.3.4 Computational Complexity 60
4.4 Performance Study 60
4.4.1 Comparison of Request Blocking Ratios 62
4.4.2 Comparison of Bandwidth Utilization Factors 64
4.4.3 Comparison of Wasted-bandwidth Utilization Factors 69
4.4.4 Comparison of Receiver Utilization Factors 72
4.4.5 Comparison of Transmitter Utilization Factors 75
4.4.6 The Effect of the Numbers of Tunable Optical Transmitters and Receivers 79
4.4.7 The Effect of the Maximum Hop Length of a Light Trail 80
4.5 Chapter Summary 84
5 Conclusion and Future Works 85
Conclusion and Future Works 85
Reference 87
Publication List 90

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