臺灣博碩士論文加值系統

隨著對無線行動通訊的需求日益提升，無論身在何處，每個人都可以用更高的傳輸速度及更經濟的方式連上網際網路。最近，無線區域網路(WLAN)被視為第三代無線通訊系統(3G)的延伸，使其無線通訊系統更能達到更強大的功能。而其中對於無線區域網路，能提供多媒體傳輸服務品質保證(QoS)就變成一個非常重要的議題。在這篇論文中，我們針對兩個不同等級的服務，在無線區域網路中延伸式分散協調式功能(EDCF)，提出一個能達到公平比例分配頻寬的方法。我們針對兩個不同的等級的服務，利用排隊模型做行為上的分析，並且分析的結果和電腦模擬來比較，由模擬結果可顯示我們可達到公平比例分配頻寬的目標，藉由依照不同的比例目標，調整不同的仲裁訊框間隔 (Arbitration Inter Frame Space) 及競爭視窗 (contention window) 可以公平比例分配頻寬。
再者，在無線區域網路中，我們提出一個在混合協調式功能(HCF)中，整合語音及數據服務的方案，結合輪詢模式(polling-based)及競爭模式(contention-based)的演算法，稱做需求輪詢機制 (on-demand polling)。藉由需求輪詢機制，我們可以在無線區域網路中，保證語音延遲的服務品質，並且有效提升數據服務的總傳輸量。

There is an increasing demand for “mobile information” that everyone can access to the Internet at high speed but with low cost whenever they are. Recently, wireless local area network (WLAN) has been considered as a complement technology for 3rd Generation (3G) technology. The quality of service (QoS) assurance is then becoming an important issue for supporting wireless multimedia services in WLAN. In this thesis, we propose a method to achieve weighted fairness for two classes of services operating under the enhanced distributed coordinator function (EDCF) mode of 802.11e. A queueing model is proposed to analyze the behavior of the two classes. The analytical results have been verified by computer simulation. Simulation results showed that the weighted fairness is achieved by adjusting the Arbitration Inter Frame Space (AIFS) and the contention window (CW) according to the assigned weights for different wireless multimedia services.
Moreover, we consider to support integrated services, such as interactive voice and non-real-time data service, in WLAN. We propose a combination of polling-based and contention-based algorithm based on HCF mode, called on-demand polling (ODP) scheme. The ODP scheme can guarantee the delay requirement of voice and increase the aggregate throughput of non-real-time data service efficiently.

中文摘要 i
Abstract ii
Acknowledgement iii
Contents iv
List of Figures vi
List of Tables viii
Chapter 11 Introduction 1
Chapter 22 On the Weighted Fairness of IEEE 802.11 WLAN under Enhanced DCF 6
2.1 Introduction 6
2.2 The IEEE 802.11 and IEEE 802.11e 9
2.2.1 The Legacy IEEE 802.11 MAC 9
2.2.2 The Enhanced DCF of IEEE 802.11e 10
2.3 Theoretical Analysis of Weighted Fairness 13
2.3.1 Definition of System Parameters and Observation Points 13
2.3.2 The Behavior of a Single Station with Different AIFS 16
2.3.3 The Frame Transmission Probabilities with Different AIFS 22
2.3.4 Throughput and Mean Access Delay 23
2.4 Numerical Examples 25
2.5 Concluding Remarks 41
Chapter 33 Protocol Design and Performance Analysis for Voice over 802.11e HCF 42
3.1 Introduction 42
3.2 System Overview 45
3.2.1 The Legacy IEEE 802.11 MAC 45
3.2.2 Hybrid Coordination Function in 802.11e 47
3.2.3 Two-Way Conversational Voice Source 49
3.3 The On-Demand Polling Scheme 50
3.4 Performance Analysis for ODP scheme 55
3.4.1 Analysis of Two-Way Conversational Voice Source 56
3.4.2 Mean Contention Time of Real-Time Voice QSTA 57
3.4.3 Frame Transmission Probability of Non-Real-Time Data QSTA 60
3.4.4 Aggregate Throughput of Non-Real-Time Data QSTA 64
3.5 Simulation results 66
3.6 Concluding Remarks 69
Chapter 44 Conclusion 70
Bibliography 72

[1] 3GPP TR 22.934, “Feasibility study on 3GPP system to wireless local area network (WLAN) interworking,” v. 1.0.0, Release 6, Feb. 2002.
[2] IEEE Standard for Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications, IEEE Std 802.11, Aug. 1999.
[3] IEEE Standard for Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications: Medium Access Control (MAC) Enhancements for Quality of Service (QoS), IEEE Std 802.11e/D3.0, Feb. 2003.
[4] D. Qiao and K.G. Shin, ”Achieving Efficient Channel Utilization and Weighted Fairness for Data Communications in IEEE 802.11 WLAN under the DCF ” Tenth IEEE International Workshop on Quality of Service, pp. 227 -236, 2002.
[5] T. Nandagopal, S. Lu, and V. Bharghavan, “A Unified Architecture for the Design and Evaluation of Wireless Fair Queueing Algorithms,” ACM MOBICOM, Aug. 1999.
[6] S. Lu, V. Bharghavan, and R.Srikant, “Fair Scheduling in Wireless Packet Networks,” ACM SIGCOMM, Cannes, France, Aug. 1997.
[7] M. A. Visser and M.E. Zarki, “Voice and Data Transmission over an 802.11 Wireless Network,” IEEE PIMRC, Toronto, Canada, Sept. 1995.
[8] G. Bianchi, L. Fratta, and M. Oliveri, “Performance Evaluation and Enhancement of the CSMA/CA MAC Protocol for 802.11 Wireless LANs,” IEEE PIMRC, Taipei, Taiwan, Oct. 1996, pp. 407-411.
[9] F.Cali, M.Conti, and E.Gregori, “Dynamic Tunig of the IEEE 802.11 Protocol to Achieve a Theoretical Throughput Limit,” IEEE/ACM Trans. on Networking, vol. 8, no. 6, Dec. 2000.
[10] H. Wu, S. Cheng, Y. Peng, K. Long, and J. Ma, “IEEE 802.11 Distributed Coordination Function(DCF) Analysis and Enhancement,” IEEE ICC, vol. 1,pp. 605-609, 2002.
[11] N. H. Vaidya, P. Bahl, and S. Gupta, “Distributed Fair Scheduling in Wireless LAN,” IEEE MOBICOM, Boston, MA, Aug. 2000, pp. 167-178.
[12] A. Banchs and X. Perez, ”Distributed Weighted Fair Queuing in 802.11 Wireless LAN,” IEEE ICC, vol. 5 , pp. 3121 -3127, 2002.
[13] 3GPP TSG-RAN-1, Nortel Networks, “Nortel Networks’ reference simulation methodology for the performance evaluation of OFDM/WCDMA in UTRAN”, Document R1-03-0518, Meeting #32, Paris, France, May 19-23, 2003.
[14] G. Bianchi ,”Performance Analysis of the IEEE 802.11 Distributed Coordination Function,” IEEE Journal on Selected Area in Communications, vol.18, no.3, pp. 535-547, Mar. 2000.
[15] IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Higher-Speed Physical Layer Extension in the 2.4 GHz Band, IEEE Std 802.11b-1999, Sep. 1999.
[16] S. Keshav, An Engineering Approach to Computer Networking: ATM Networks, the Internet, and the Telephone Netowrk, Addison-Wesley, 1997.
[17] B. P. Crow, I. Widjaja, J. G. Kim, P. Sakai, ”IEEE 802.11 Wireless Local Area Networks,” IEEE Comm. Mag., vol.35, no.9, pp. 116-26, Sep. 1997.
[18] B. P. Crow, I. Widjaja, J. G. Kim, P. Sakai, ”Investigate of IEEE 802.11 Medium Access Control (MAC) Sublayer Functions,” Proc. of IEEE INFOCOM 1997, vol.1, pp. 126 -133, Apr. 1997.
[19] M. Veeraraghavan, N. Cocker, T. Moors, ”Support of voice services in IEEE 802.11 wireless LANs,” Proc. of IEEE INFOCOM 2001, vol.1, pp. 488-497.
[20] ITU-T, “General Characteristics of International Telephone Connections and International Telephone Circuits One-Way Transmission Time,” G.114, Feb. 1996.
[21] P. T. Brady, “A model for on-off speech patterns in two-way conversation,” Bell Syst.Tech.J., vol. 48, pp. 2445-2472, Jan. 1969.
[22] P. T. Brady, “A statistical analysis of on-off patterns in 16 conversations,” Bell Syst.Tech.J., vol. 47, pp. 73-91, Jan. 1968.
[23] M.W. Garrett. ATM Service Architecture: From Applications to Scheduling, ATM Forum Contribution 94-0846 TM SWG, Sep. 1994.
[24] J. Crowcroft, Z. Wang, A.Smith, and J.Adams. “A Rough Comparison of the IETF and ATM Service Models,” IEEE Network Magazine, Vol.9, No.6, November/December 1995.