Adaptive Subchannel Allocation and Admission Control for the IEEE 802.16 OFDMA Systems

[[abstract]]IEEE 802.16在無線?會型網?下可提供高速無線存取的服務，而為了有效的使用頻寬資源並且達到即時性服務的品質需求，必須透過動態次通道分配和允入控制演算法來達成，但標準並未對這個部分做出定義，因此，適合的動態次通道分配和允入控制演算法將是非常重要的。 本論文中，我們針對了在IEEE 802.16的無線寬頻網路下的即時性服務提出了動態次通道分配和允入控制的方法。首先，我們會先根據目前佇列的狀態來決定downlink和uplink subframe的邊界，接著我們考慮平均封包遺失比率較大的連線和可以使用最好調變的連線優先分配。此外，我們利用統計多筆連線近似成一個高斯分佈，並且基於高斯分佈所設定的封包遺失比率來判斷新的連線是否可以被建立或是拒絕。 在本論文中，我們考慮了實體層和媒體存取控制層，希望透過跨層的設計得到一個較高的頻譜效率並符合服務品質的需求，從模擬的結果可以證明我們所提出的演算法確實可以有效的提升頻率效率並符合服務品質的需求。[[abstract]]The IEEE 802.16 provides high-speed wireless access in Metropolitan Area Network. In order to use bandwidth resource efficiently and guarantee QoS requirement of real-time service, adaptive subchannel allocation and admission control are necessary. However, methods for adaptive subchannel allocation and admission control were not defined in the standard. Therefore, feasible adaptive subchannel allocation and admission control algorithms are very important. In this thesis, we present an adaptive subchannel allocation and admission control method for real-time services in the IEEE 802.16 broadband wireless networks. First, we select the position of the boundary between the downlink and uplink subframes according to current queue status. Second, the subchannels are allocated to proper connections based on their current loss rate and modulation scheme. Moreover, by modeling the aggregated traffic as a Gaussian distribution, we perform the admission control by checking if there is enough resource to guarantee the loss rate. In this thesis, we consider the physical layer and the MAC layer. By cross-layer design, we hope achieve high spectral efficiency, and guarantee quality-of-service (QoS) requirements. Simulation results show that the proposed algorithm can increase spectral efficiency and meet the QoS requirement for real-time services.[[note]]碩