- 學位論文
具QoS的無線區域網路之HCCA MAC允入控制與資源配置
Optimal Admission Control and Resource Allocation for WLAN HCCA MAC with QoS Guarantee
摘要
隨著在無線區域網路中多媒體應用的廣泛使用，因此在無線區域網路中支援QoS也將變的越來越重要。為了支援即時性(real-time)的多媒體應用並提供QoS保證，因而有了IEEE 802.11e標準之制定。雖然IEEE 802.11e已經制定了具有QoS功能的MAC層，但是如何把這些機制應用在QoS的議題上，並沒有明確的指示。而在這些QoS議題的研究中，兩種較為有效的作法：adaptive contention window和加入call admission control則是同時具有挑戰性及實際效果的提案。本論文旨在探討多媒體影音資料在無線區域網路上傳遞時所遇到的問題，期盼能夠在滿足服務品質QoS (Quality of Service)保證的前提之下，找出最佳無限資源配置方案。本論文係根植於IEEE 802.11e之EDCA媒介存取機制下，將多媒體服務資料型態分類後，再附以不同的優先權的觀念，到免競爭傳輸(CFP)週期下的HCCA存取機制下的同步式訊框(Beacon)之資源架構，再利用MDP理論建立其數學模型，以求取最佳之允入與無線通道資源配置方案，並經由各項數據分析驗證最佳方案的效能。
並列摘要
With the extensive use of multimedia applications, supporting QoS in wireless networks draws a lot attention from researchers and service providers. In order to support real-time multimedia application and provide QoS guarantee for IEEE 802.11-based WLAN, the standard IEEE 802.11e arose. Although IEEE 802.11e defined both EDCA and HCCA MAC functions for QoS, how to implement the functions in reality remains unspecified. Many studies made efforts on QoS issues. Among those proposals, two categories, adaptive contention window control and applying call admission control, revealed the effectiveness and challenge in both aspects of research and practice. This research investigated the QoS problems for wireless multimedia communication and developed an effective admission control strategy for IEEE 802.11e HCCA mechanism under a non-competitive transmission cycle. Based on the QoS support on IEEE 802.11e EDCA MAC, the wireless traffics were categorized into four classes with different bandwidth requirements and access priority. This thesis properly modeled the system resource as multiple time slots and applied the theory of Markov Decision Process to setup the mathematical model for admission control of resource allocation. The analytical model for optimal admission control policy was then solved by linear programming. Various numerical results and discussion presented the effectiveness and performance of the design proposed by the thesis, in comparison to that with no control.