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무선 메쉬 네트워크를 위한 효율적인 라우팅 기법 연구

Improving Efficiency of Routing Protocols for Wireless Mesh Networks

초록/요약

최근 수년 사이 무선 메쉬 네트워크(Wireless Mesh Network: WMN)가 간편한 망 구축과 낮은 비용, 그리고 높은 확장성과 같은 장점을 바탕으로 차세대 기간통신망 기술로써 주목 받고 있다. 메쉬 네트워크 기술은 무선 다중 홉 통신에 기반을 두고 있기 때문에, 메쉬 단말 간에 효율적인 경로를 설정하는 것이 무엇보다도 중요한 문제이다. 본 논문에서는 메쉬 네트워크의 특성을 살펴보고, 이를 바탕으로 효율적인 라우팅 프로토콜이 반드시 고려해야 하는 요구 사항에 대해 정리하였다. 또한 라우팅 프로토콜을 크게 단일한 목적지 주소를 갖는 유니캐스트 라우팅과 다수의 단말로 구성된 그룹에게 위치 정보를 기반으로 데이터를 전송하는 지오캐스트 라우팅으로 구분하여, 각각의 경우에 적합한 라우팅 기법을 연구하였다. 유니캐스트 라우팅을 위해서는 무선 채널 특성을 반영하면서 동시에 IEEE 802.11s 표준과 호환이 가능한 기법을 제안하였으며, 또한 보다 높은 성능을 제공할 수 있는 링크 상태 기반의 새로운 MAC 계층 라우팅 기법을 제안하였다. 그리고 다수의 목적지 영역에 효율적으로 데이터를 전달할 수 있는 지오캐스트 라우팅 기법을 제안하였다. 이와 같이 본 논문에서 제시하는 무선 메쉬 네트워크에 특화된 라우팅 기법을 이용하여 네트워크의 성능을 극대화할 수 있을 것으로 기대한다.

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초록/요약

In the last decade, wireless mesh networks (WMNs) have received great attention as a next-generation wireless multi-hop infrastructure, thanks to many of its advantages such as easy deployment, low management cost and good scalability. Since WMNs are inherently based on the multi-hop wireless communication, it is the most important to select efficient paths between communicating nodes. This thesis first summarizes characteristics of WMNs and the design considerations for developing efficient routing protocols. We categorize routing protocols into two groups; unicast routing protocols and geocast routing protocols for location based group communication, and then we have conducted research to develop the efficient solutions for each group. For unicast communication, we propose a channel aware routing protocol which is fully compatible with the IEEE 802.11s that is a standard for wireless LAN mesh networks. In other to achieve better performance in the multi-interface and multi-channel environment, the lightweight link-state routing protocol is proposed as another solution for unicast communication. Moreover, we propose an efficient geocast protocol that efficiently delivers data to the multiple target groups. This thesis provides performance evaluation of the proposed protocols by simulation and testbed studies as well as the theoretical analysis. Therefore, the proposed routing protocols are expected to increase capacity and performance of WMNs.

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목차

CHAPTER 1 INTRODUCTION 1
1.1 Design Considerations to Develop Efficient Routing Protocols 3
1.1.1 Network Layer vs. MAC Layer 3
1.1.2 Consideration of Multi-interface and Multi-channel 5
1.1.3 Standard-based Approach 6
1.1.4 Utilization of Location Information 7
1.2 Classifications of Routing Protocols 8
1.3 Contributions of This Thesis 11
1.4 Thesis Overview 11
CHAPTER 2 RELATED WORKS 13
2.1 Standard Activity for Wireless LAN based Mesh Networks 13
2.2 Unicast Routing Protocols 16
2.2.1 How to Use Multi-channel and Multi-interface 16
2.2.2 Link-state Routing Protocols in Wireless Multi-hop Networks 17
2.2.3 Analysis and Evaluation of the HWMP 18
2.2.4 Implementations of the IEEE 802.11s Standard 18
2.3 Geocast Routing Protocols 19
CHAPTER 3 AN EFFICIENT ROUTING PROTOCOL COMPATIBLE WITH THE WLAN MESH STANDARD 22
3.1 Introduction 22
3.2 Preliminary Analysis: Path Instability Problem of the HWMP 25
3.3 Proposed Scheme 27
3.3.1 Channel-aware Path Selection Phase 27
3.3.2 Control Message Reduction Phase 31
3.4 Performance Evaluation 33
3.4.1 Simulation Study 33
3.4.2 Testbed Implementation 39
3.4.3 Experiment Results 40
3.5 Chapter Summary 48
CHAPTER 4 A LIGHTWEIGHT LINK-STATE ROUTING PROTOCOL 49
4.1 Introduction 49
4.2 Proposed Scheme 50
4.2.1 Lightweight Link-state Update Phase 51
4.2.2 Path Selection Phase 53
4.3 Performance Evaluation 55
4.3.1 Theoretical Analysis 55
4.3.2 Testbed Implementation 57
4.3.3 Experiment Results 59
4.3.4 Performance Comparison between Proposed Schemes 65
4.4 Chapter Summary 68
CHAPTER 5 AN EFFICIENT GEOCAST ROUTING PROTOCOL WITH MULTI-TARGET REGIONS 69
5.1 Introduction 69
5.2 Background: the Geometric Concept of Fermat Point 71
5.3 Proposed Schemes 73
5.3.1 Simple Region Chaining Scheme 73
5.3.2 Basic Fermat Point Based Scheme in a Simple Case 74
5.3.3 Generalized Fermat Point Based Schemes: Multiple Fermat Point and Fermat Point Chaining 76
5.4 Performance Evaluation 78
5.4.1 Theoretical Analysis 78
5.4.2 Simulation Environment 80
5.4.3 Simulation Result 81
5.5 Chapter Summary 89
CHAPTER 6 CONCLUSIONS 90
6.1 Achievements 92
6.2 Limitations and Future Works 94
REFERENCES 95

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