為了因應近年來不斷發展的網路多媒體娛樂以及應用，無線寬頻網路也不斷的快速發展，其中IEEE802.16WiMAX是最近熱門的新技術之一。WiMAX網路為了服務各種不同的連線需求，將所有的資料連線分成五類，分別是非請求的頻寬分配(UGS)，即時輪詢服務(rtPS)，擴展即時輪詢服務(ertPS)，非即時輪詢服務(nrtPS)和盡力服務(BE)。這五種類型的資料連線分別有其相對應的服務品質參數。在WiMAX基地台裡，排程器負責決定哪條連線的資料需要優先送出以及頻寬的分配，因此在排程器中可以因應網路供應商不同的策略來改變排程的方法。如果一個排程器設計得不好，可能會造成頻寬的浪費，或者是網路服務品質的低落。 此論文提出了一個以IEEE 802.16無線都會網路通道狀態為主之具服務品質保證的排程器。此排程器考慮了服務品質參數中的最大延遲時間，能夠保證即時輪詢服務連線的最大延遲時間。除了滿足服務品質參數之外，此排程器另外考慮了各個連線的網路通道狀況，並優先服務通道狀況良好的連線，因此此排程器能夠使網路整體的吞吐量達到最高。從模擬結果可以看出此排程器除了滿足服務品質參數外並且與其他排程器相比擁有較高的整體網路吞吐量。 In order to response the developing of internet multimedia and application, Broadband Wireless Access (BWA) systems are also developed quickly. IEEE 802.16 WiMAX is one of the hottest new technologies in recent years. For the sake of serving different kinds of connections, IEEE 802.16 WiMAX classifies data connections into five types. These types are Unsolicited Grant Service (UGS), Real-time Polling Service (rtPS), Non-real-time Polling Service (nrtPS), and Best Effort (BE). Each type of connections has its own corresponding quality of service (QoS) parameters. In a WiMAX base station (BS), the scheduler is responsible for that which packet should be sent first and how the bandwidth would be allocated. Thus the network provider can change the scheduling algorithm in the scheduler according to policies. If a scheduler uses an improper scheduling algorithm, the scheduler may waste bandwidth or lower the quality of service of connections. This thesis proposes a channel-aware QoS scheduler for IEEE 802.16 wireless metropolitan networks. This scheduler mainly considers WiMAX QoS parameter: the Maximum Latency. It is able to guarantee the Maximum Latency of rtPS connections. In addition to QoS parameter, the proposed scheduler also considers the channel condition of each connection and first serves the connections which have better channel condition. Thus the proposed scheduler can maximize the total throughput of the network. Simulation results also show that the proposed scheduler not only guarantees the QoS but also has better total network throughput than other schedulers.
