臺灣博碩士論文加值系統

隨著無線技術漸漸地被普遍採用來架構區域網路，以無線方式傳輸資料的品質愈加重要。參考文獻[1]中，由電氣和電子工程師協會（IEEE）所提出的802.11標準中提出一種無線網路傳輸資料的方法，稱為基礎建設模式（Infrastructure mode）。在基礎建設模式的無線網路中，所有的無線裝置都要透過一台稱為存取中心（Access point）的機器來接收或傳送資料。若是一個無線主機可以有機會連接到多個存取中心來傳輸資料，此無線主機便可以選擇能夠提供最好傳輸頻寬的存取中心來連接上網。如何判斷哪一台存取中心能提供較好的傳輸頻寬，便是本論文所要研究的問題。
在本論文中，我們提出一個新的設計去研究如何在基礎建設模式的無線網路中達到動態平衡頻寬分配，除了無線主機可以根據無線訊號的強度大小來選擇存取中心，為了達到更有效的頻寬利用，我們會根據無線頻寬的使用情況來動態分配所有無線主機與存取中心的連結，如此無線主機可以分配到較高的使用頻寬，而整個無線區域網路所能提供的總傳輸頻寬也能盡可能地被充分的使用。

As the wireless technology gradually becomes a common solution to set up a local area network (LAN) , the quality of transmitting data on the wireless media is more important. One application of wireless local area network (WLAN) is called the “infrastructure mode”, which is proposed in the IEEE Std 802.11[1]. An infrastructure-mode wireless LAN is a centralized wireless network in which all wireless stations (STAs) send or receive their data through a special device called the “access point (AP)”. If there are more than one AP that a wireless STA can connect to, the wireless STA can choose and connect to the one that can provide the best transmission quality. What we want to discuss in this thesis is how a wireless STA chooses the AP that can provide the highest
transmission bandwidth.
In this thesis, we propose a new design which is suitable for infrastructure-mode wireless networks. This new design supports dynamic load balancing under the infrastructure-mode. It distributes all wireless STAs to all APs not only based on the strength of wireless signal power, but also based on these APs’ dynamic wireless link utilizations. Thus, a wireless STA can get a higher transmission bandwidth, and the total bandwidth provided by the whole wireless network can be better
utilized.

Table of Contents
1 Introduction
1.1 Infrastructure mode wireless network
1.2 Motivation
1.3 Related work
1.4 Organization
2 Dynamic Load Balancing
2.1 Basic mechanism
2.1.1 Assumptions
2.1.2 Definition
2.1.3 Control message types
2.2 Operation overview
2.2.1 Information exchange between APs
2.2.2 Policies of dynamic load balancing
2.2.2.1 Policies for an AP
2.2.2.2 Policies for a STA
3 Simulation Results
3.1 Simulation tool
3.2 Simulation examples
3.3 Result discussion
4 Conclusion
Future work
Reference

References
[1] IEEE Std 802.11 Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, June (1997).
[2] Shiann-Tsong Sheu and Chih-Chiang Wu, “Dynamic Load Balance Algorithm (DLBA) for IEEE 802.11 Wireless LAN”, Tamkang Journal of Science and Engineering, vol 2, No 1, pp.45-52 (1999).
[3] I. Papanikos and M. Logothetis, “A Study on Dynamic Load Balance for IEEE 802.11b Wireless LAN”, Proc. 8th International Conference on Advances in Communication & Control, COMCON 8, Rethymna,
Crete, June, 2001.
[4] C. H. Huang, “The Design and Implementation of the NCTUns 1.0 Network Simulation Engine”, master thesis, National Chiao Tung University, Hsinchu, Taiwan, 2002.