臺灣博碩士論文加值系統

IEEE 802.16標準是針對無線城域網路(Wireless Metropolitan Area Network)而設計的，它支援服務品質(QoS)，而且具有相當高的傳輸速率。每一種應用服務都有不同的型態，根據這些不同的型態，802.16 定義了四個不同的服務品質類別。然而，最關鍵的部份－封包排程卻沒有被定義在802.16標準裡面。在這篇論文中，我們提出了一套完整的允入控管(call admission control)和上行封包排程的架構。首先，我們先以令牌桶(token bucket)機制為基礎，設計了一套802.16專用的允入控管和上行封包排程的模組。接著我們介紹如何將令牌桶機制套用至一般的連線。我們找出了一個預測連線的延遲(delay)和漏失率(loss rate)的模型，接著可以利用這個模型，並透過簡單的搜尋演算法來找出適合的令牌速率和令牌桶的大小。模擬的結果表示，我們的允入控管和上行封包排程能夠確實對具有即時性質的連線的提供保證，且我們將令牌桶機制套用到一般連線的模組也能準確的運作。最後，我們也提出了一個簡單的整合實例並評估其效能。

The IEEE 802.16 standard was designed for Wireless Metropolitan Area Network (WMAN). It supports QoS and has very high transmission rate. According to different application types, there are four QoS classes defined in the IEEE 802.16 standard. The key part of 802.16 for QoS– packet scheduling, was undefined. In this thesis, a complete call admission control (CAC) and uplink packet scheduling is presented. We first proposed a token-bucket based uplink packet scheduling combined with CAC. Then a model of characterizing traffic flows by token bucket parameters, namely token rate and bucket size, is presented. We proposed a queuing model to predict the delay and loss rate for a token bucket controlled traffic flow. In order to fulfill token bucket based CAC, we need to find appropriate token rate and bucket size for any flows. A simple search algorithm coupled with our queuing model can be used to achieve this. Multiplexing of two traffic flows is also introduced. The simulation results show that our CAC and uplink packet scheduling can promise the delay requirement of real-time flows and prevent each class from starvation. The precision of our token rate estimation model is also validated. Finally, a simple integration of our CAC, uplink scheduling, and multiplexing is evaluated.

CHAPTER 1 Introduction 1
1.1 Background 2
1.1.1 Token Bucket Mechanism 2
1.1.2 The IEEE 802.16 Standard 3
1.2 Motivation 7
1.3 Organization 8
CHAPTER 2 Related Work 9
CHAPTER 3 CAC and Uplink Packet Scheduling 17
3.1 Call Admission Control (CAC) 17
3.1.1 The Bandwidth Requirements of rtPS flows 18
3.1.2 The CAC Algorithm 21
3.2 Uplink Packet Scheduling Algorithm 25
CHAPTER 4 Token Rate Estimation Model 28
4.1 Case of Infinite Queue 28
4.1.1 Case Analysis 29
4.1.2 Markov Chain State 30
4.1.3 Results 33
4.2 Case of Finite Queue 37
4.2.1 Case Analysis 37
4.2.2 Markov Chain State 38
4.2.3 Results 40
4.3 A Simple Search Algorithm 45
CHAPTER 5 Simulation Results 47
5.1 CAC and Uplink Packet Scheduling 47
5.2 Token Rate Estimation Model 50
5.2.1 Case of Infinite Queue 50
5.2.2 Case of Finite Queue 52
5.3 Multiplexing 53
CHAPTER 6 An Example of Integration 55
CHAPTER 7 Conclusions and Future Work 58
REFERENCES 60

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