全球互通微波存取(WiMAX)是新一代的無線寬頻網路存取技術，相較於傳統有線網路，WiMAX架設費用以及之後的維護費用較為廉價，因此它亦成為一個解決"最後一哩"問題的不錯方案。由於現代網路及其應用的多樣性，所以在IEEE所定義的WiMAX標準中提供了五種不同的等級的服務類別(service class)，藉以支援系統裡不同的服務質量(Quality of Service)。而IEEE特意將允入控制 (admission control)以及封包排程 (packet scheduling)的相關機制空下不做定義，為的是要提供WiMAX供應商有各自自由發揮的空間，讓他們能以有效或以特殊目的為主的方式來分配資源。

本篇論文提出一個是適用於WiMAX網路中的允入控制以及一個封包排程演算法稱為 "Revenue-Aware Scheduling (RAS)"。允入機制中我們利用從RAS裡傳回的回饋資訊來調整保留給欲進入系統之連線的頻寬，而在RAS中我們首要服務的是那些尚未達到QoS要求的連線，接著再以能獲得較多收益的方式來選擇要服務的連線，最後再以佇列長度以及所使用的調變及編碼方式(Modulation and Coding Scheme)當作依據來分配剩餘資源。

為了評估所提出的方法，我們進行了一些不同情況的模擬來驗證，模擬結果顯示我們所提出的允入控制以及封包排程演算法可以讓我們在收益這方面有不錯的表現。

Worldwide Interoperability for Microwave Access (WiMAX) standard represents a new generation technology for high speed Broadband Wireless Access (BWA) system. Because of the lower cost on the infrastructure installation and maintenance, it becomes a good solution of last mile problem. Due to the diversity of modern network systems and their applications, WiMAX standards define five service classes to support different Quality of Service in the system. IEEE allows WiMAX vendors to design their admission control schemes and scheduling algorithms to achieve the efficiency or some special purpose of allocating network resources. Many scheduling algorithms have been proposed for WiMAX system. However most of them do not consider the revenue issues from service providers' standpoint.

In this thesis, we propose an admission control scheme and a packet scheduling algorithm – Revenue-Aware Scheduling algorithm (RAS) in the WiMAX MAC layer. In admission control scheme, we use the feedback from RAS and adjust the reserved bandwidth for the incoming connections. In RAS, the connections that do not meet their Quality of Service (QoS) requirements will be served first. Then RAS will choose the connections from which can obtain the most revenue to serve. Finally, RAS will allocate the residual resource to connections based on their queue length and Modulation and Coding Scheme (MCS).

To evaluate the proposed scheme, we perform some simulations with different scenarios. Our simulation results show that our proposed admission control scheme and RAS can obtain more revenue.

[1] IEEE, “IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems,” IEEE 802.16-2001.
[2] IEEE, “IEEE Standard for Local and Metropolitan Area Networks – Part 16: Air Interface for Fixed Broadband Wireless Access Systems – Amendment2: Medium Access Control Modifications and Additional Physical Layer Specifications for 2-11 GHz,” IEEE 802.16-2003.
[3] IEEE, “IEEE Standard for Local and Metropolitan Area Networks. Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems. Amendent 2:Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation I Licensed Bands and Corrigendum 1,” IEEE 802.16e-2005.
[4] N. Abu Ali, P. Dhrona, H. Hassanein, “A Performance Study of Scheduling Algorithms in Point-to-Multipoint WiMAX Networks,” IEEE Conference on Local Computer Networks, 2008, (LCN 2008), pp. 843 – 850.
[5] H. Artail, M. Karam, S. Khayat, H. Safa and R. Soudan, “New Scheduling Architecture for IEEE 802.16 Wireless Metropolitan Area Network,” IEEE/ACS International Conference on Computer Systems and Applications, 2007, pp. 203 – 210.
[6] A. Asadi and T.S. Wei “An Enhanced Cross Layer Downlink Scheduling Algorithm for IEEE 802.16 Networks,” International Conference on Information Networking, 2011, (ICOIN 2011), pp. 212 – 217.
[7] D. Black, S. Blake, M. Carlson, E. Davies, Z. Wang, and W. Weiss, “An Architecture for Differentiated Services,” IETF RFC 2475, Dec. 1998.
[8] J.F. Borin and N. da Fonseca, “Admission Control Policies for Revenue and Utility Maximization in IEEE 802.16 networks,” IEEE Global Telecommunications Conference, 2010, (GLOBECOM 2010), pp1 – 5.
[9] J.F. Borin and N. da Fonseca, “Uplink Scheduler and Admission Control for the IEEE 802.16 standard” IEEE Global Telecommunications Conference, 2009, (GLOBECOM 2009), pp. 1 – 6.
[10] R. Braden, D. Clark, and S. Shenker, “Integrated Services in the Internet Architecture: an Overview,” IETF RFC 1633, Jun. 1994.
[11] J. Chen, W. Jiao and H. Wang, “A Service Flow Management Strategy for IEEE 802.16 Broadband Wireless Access Systems in TDD Mode,” IEEE International Conference on Communications, 2005, (ICC 2005), vol 5, pp. 3422 – 3426.
[12] N. Chilamkurti, C-K Shieh, P-C Ting; C-Y Yu, T-H Wang, “A Proposed RED-based Scheduling Scheme for QoS in WiMAX Networks,” IEEE International Symposium on Wireless Pervasive Computing, 2009, (ISWPC 2009), pp.1 – 5.
[13] C. Cicconetti, C. Eklund, L. Lenzini, E. Mingozzi, “Quality of Service Support in IEEE 802.16 Networks,” IEEE Network Magazine,2006, Vol 20, Issue 2, pp. 50 – 55.
[14] Debabrata Das, D. Jayaram, N. Sreenivasulu, K. Vinay, “Performance Evaluation of End-to-End delay by Hybrid Scheduling Algorithm for QoS in IEEE 802.16 Network”, IEEE International Conference on Wireless and Optical Communications Networks, 2006, pp. 11 – 13.
[15] A. Ganz, and K. Wongthavarawat, “Packet scheduling for QoS support in IEEE 802.16 broadband wireless access systems,” International Journal of Communication Systems, 16(1):81 – 96, February 2003.
[16] G.B. Giannakis, Q. Liu, X. Wang, “Cross-Layer Scheduler Design with QoS Support for Wireless Access Networks,” IEEE International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks, 2005, pp. 8 – 21.
[17] H. Liu and G. Li, “OFDM - Based Broadband Wireless Network – Design and Optimalization,” first edition, 2005, ISBN:0-471-72346-0.
[18] H.A. Mantar, M. Oktay, “A Real-Time Scheduling Architecture for IEEE 802.16 - WiMAX Systems,” IEEE International Symposium on Applied Machine Intelligence and Informatics, 2011, (SAMI 2011), pp. 189 – 194.
[19] H.K. Rath and A. Karandikar, “On TCP-aware uplink scheduling in IEEE 802.16 networks,” International Conference on Communication Systems Software and Middleware and Workshops, 2008, (COMSWARE 2008), pp. 349 – 355.
[20] H.K. Rath, A. Karandikar, “Performance Analysis of TCP and UDP-based Applications in a IEEE 802.16 deployed Network,” International Symposium on Wireless Personal Multimedia Communications (WPMC), 2011, pp. 1 – 5.
[21] H.K. Rath, A. Karandikar and V. Sharma, “Adaptive Modulation-based TCP-Aware Uplink Scheduling in IEEE 802.16 Networks,” International Conference on Communications, 2008, (ICC 2008), pp. 3230 – 3236.
[22] M. Shreedhar, G. Varghese, “Efficient fair queuing using deficit round-robin,” IEEE/ACM Transactions on Networking, 1996, vol 4, Issue 3, pp. 375 – 385.
[23] AT &T charge plans , March 2012
Available at http://www.att.com/shop/wireless/plans.html
[24] Verizon charge plans , March 2012
Available at http://www.verizonwireless.com
[25] The network simulator - NS2 Notes and documentation and source code Available at http://www.isi.edu/nsnam/ns/