隨著網路的快速發展，使用者對於網路的應用也漸漸改變，從一開始的單一資料傳輸演變成多媒體傳輸。但在有限的網路資源下，不同資料類型會有不同的品質要求，而服務品質(Quality of Service, QoS)是一種控制機制，它針對不同使用者或者不同資料類型的資料流採用相應的優先順序，或者是根據應用程式的要求，保證資料流的效能達到一定的水準。
無線網狀區域網路是由一些支援網狀服務(mesh service)的節點所組成的通訊網路。在IEEE802.11s草案中，除了導入網狀網路架構外，亦加入以預約為基礎的存取機制，稱為MDA(mesh deterministic access)。MDA能讓節點以較少的競爭與碰撞來進行無線存取。而在之前的研究中，有提出可以讓MDA運行在多通道環境下的機制，稱之為Multi-channel MDA(MMDA)。但在MMDA的機制下，並沒有針對不同的資料類型給予不同的傳輸優先順序，所以本論文便是延伸之前的研究，針對MMDA加入服務品質的機制。
由於MMDA將mesh DTIM interval切割為競爭區間(Contention Period)及資料傳輸區間(Data Transmission Period)。本論文提出了在競爭區間時根據節點內資料類型的組成，來改變節點的後退時間(backoff time)，讓資料組成之中擁有較多高優先權資料的節點可以提高預約到MDA Opportunity(MDAOP)的機率。而在資料傳輸區間以期限(deadline)以及權重循環(Weighted Round Robin, WRR)排序來進行佇列傳送的排序。使得高優先權的資料在佇列中能有較高的傳送優先權，以減少資料被丟棄的機會，來提升高優先權資料的傳輸效能。

With the rapid development of the Internet, the user application for network has changed from a single data transmission into multimedia transmission. However, the Internet resources are limited. Quality of service (QoS) is a control mechanism. It provides different users or different types of data stream use the corresponding priority, or base on the application requirements to ensure the performance of the data stream to reach certain level.
A wireless mesh LAN is a communications network made up of radio nodes that support Mesh service. In IEEE 802.11s draft, not only the Mesh network topology be introduced, but also a new reservation based MAC access scheme, MDA, be introduced. Nodes that support MDA can access wireless medium with lower collision probability. In a previous study, it was suggested so that MDA can operate on multi-channel environment. Compared with the MDA, MMDA does effectively enhance the system performance. It doesn't offer different data types to have different transmission priorities in MMDA, so we propose to add the quality of service for MMDA based on previous research.
MMDA divides mesh DTIM interval into Contention Period and Data Transmission Period. This paper propose a scheme, which change the node backoff time according to data type composition in node at Contention Period, the data which is composed of high-priority data in node will have more chance to reservation MDA Opportunity (MDAOP). In this thesis we consider deadline and use Weighted Round Robin (WRR) to sort the queue in Data Transmission Period. Makes high-priority data in the queue have a higher chance to transfer data, to reduce drop ratio, enhance high-priority data transmission performance.

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