臺灣博碩士論文加值系統

公平性與服務品質(QoS)是無線寬頻網路中最被重視的問題，對於不同使用者、在不同的環境下，除了要達到不同的服務需求之外，同時還必須兼顧公平性。IEEE 802.16 (WiMAX)在無線寬頻網路中是目前全球最被積極開發的一項技術標準，其中IEEE 802.16j 行動多重轉遞(Mobile Multi-hop Relay)是以IEEE 802.16e為基礎作延伸，目的在於強化移動式WiMAX的系統效能。透過建立轉遞站(relay station)改善基地台涵蓋區域邊緣或掩蔽物造成的訊號不良問題。雖然經由轉遞站能夠擴增涵蓋範圍跟避免掩蔽物影響，不過卻會占用額外的無線資源，這可能造成系統整體容量跟服務品質的下降。因此，本研究目的在於如何透過路徑選擇與排程演算法保證公平性與服務品質。並且，此演算法能同時適用於移動式WiMAX和多重轉遞網路。本篇論文提出同時保證移動式WiMAX和多重轉遞網路公平性與服務品質之跨協定模糊控制 (FQCFC) 排程機制。我們使用跨協定設計來建立不同協定層之間的關係，其中包含應用層運輸需求(TSPEC)、網路層路徑選擇、媒體存取層排程、以及實體層調變機制之間的互動等，並且使用回饋控制來適應動態環境。因為動態環境種種不確定性的影響，標準的控制器很難找到數學模型去代表其行為。所以我們利用模糊控制來解決不確定性的問題，例如:會隨時間改變的流量規格以及通道的干擾等。我們提出的控制器根據服務品質的需求與服務級別，分別調整每條連線的優先權和傳送機會。讓相同級別的連線得到相同程度的服務品質，同時讓沒有服務品質需求的連線公平地分享剩下的資源，藉由這兩個重要的觀念來提供級別內部和不同級別之間的公平性保證。即使在動態的環境，例如會隨時間改變流量規格的移動式WiMAX或者多重轉遞網路，FQCFC能公平地保證延遲、傳輸量、延遲變化量等效能，現今既有文獻中這些保障很少能被同時達成並且維持公平性。

Fairness and quality of service (QoS) are the most important issues for broadband wireless access networks since for various users in different environment guaranteeing diverse QoS and fairness at the same time is necessary. IEEE 802.16 (WiMAX) is the most popular standard for broadband wireless access networks, among which IEEE 802.16j multi-hop relay is an amendment to enhance coverage and throughput of IEEE 802.16e mobile WiMAX by introducing multi-hop relay capacities. Multi-hop relay can improve the performance for subscriber stations near the edge of the cell or in a deep shadowed region. However, transmission through relay station will consume the extra resources in relay link. This may cause the decreases of system capacity and QoS. Our purpose is to guarantee fairness and QoS by path selection and scheduling scheme for mobile WiMAX and multi-hop relay networks. A Fairness and QoS guaranteed scheduling scheme with Cross-layer Fuzzy Controls (FQCFC) is proposed for mobile WiMAX and Multi-hop Relay networks. We use cross-layer design to establish the relationships between different protocol layers, which include the interactions of the requirements (TSPEC) transmission in application layer, path selection in network layer, scheduling in medium access control (MAC) layer, and modulation scheme in physical (PHY) layer. For adapting dynamic environment, we use feedback control theory. However, classical controller requires modeling of the physical reality. It is difficult or even impossible to construct precise mathematical models due to the time-varying of the processes, channel interference, dynamics and uncertainty in mobile environment. We use fuzzy controller to solve the dynamic and uncertainty problems. The proposed controllers respectively adjust priority and transmission opportunity (TXOP) for each connection according to QoS requirements and service classes. The FQCFC provides intra- and inter-class fairness guarantees by making connections within the same class achieve equal degree of QoS while at the same time making those without QoS requirements equally share the remaining resources. Even in dynamic environments such as mobile WiMAX with time-variant traffic specifications or multi-hop relay networks, the FQCFC fairly guarantees delay, throughput and jitter, which are seldom achieved at the same time by state-of-the-art solutions.

LIST OF TABLES VIII
LIST OF FIGURES IX
CHAPTER 1 INTRODUCTION 1
1.1 MOTIVATION 1
1.2 CONTRIBUTIONS 2
1.3 ORGANIZATION OF THIS PAPER 2
CHAPTER 2 BACKGROUND 4
2.1 OVERVIEW OF WIMAX 4
2.1.1 PHY layer in WiMAX 5
2.1.2 MAC layer in WiMAX 9
2.2 IEEE 802.16J MOBILE MULTI-HOP RELAY 12
2.2.1 IEEE 802.16j MMR Network Architecture 13
2.2.2 Frame structures of BS and RS 14
2.3 FUZZY CONTROLLER 16
2.4 CROSS-LAYER DESIGN 17
CHAPTER 3 RELATED WORKS 20
3.1 SCHEDULING MECHANISM 20
3.1.1 Optimization problem 20
3.1.2 Priority-based method 22
3.2 FAIRNESS TYPES 23
3.2.1 Proportional Fairness 24
3.2.2 Max-min Fairness 24
3.2.3 The Proposed Fairness 25
3.3 RS SELECTION SCHEME 25
CHAPTER 4 THE FQCFC DESIGN FOR MMR NETWORKS 28
4.1 SYSTEM ARCHITECTURE 28
4.2 RS SELECTOR IN NETWORK LAYER 29
4.3 SCHEDULER IN MAC LAYER 30
4.3.1 System plant 31
4.3.2 Controller design for Real-time connections 32
4.3.3 Controller design for nrtPS connections 41
4.3.4 Controller design for BE connections 44
4.3.5 Adaptive for MMR networks 44
4.4 LINK ADAPTOR IN PHY LAYER 45
CHAPTER 5 SYSTEM PERFORMANCE EVALUATIONS 47
5.1 FAIRNESS CRITERIA 47
5.1.1 Intra-class fairness index 47
5.1.2 Inter-class fairness index 49
5.2 SIMULATION CONFIGURATION 50
5.2.1 Mobile WiMAX 52
5.2.2 MMR networks 54
5.3 PERFORMANCE EVALUATION 55
5.3.1 Mobile WiMAX 55
5.3.2 MMR networks 59
CHAPTER 6 CONCLUSION AND FUTURE WORK 73
6.1 CONCLUSION 73
6.2 FUTURE WORKS 74
REFERENCES 75

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