無線網狀網路(Wireless Mesh Networks)因為具有建置容易跟成本低廉的優點，已成為目前熱門的廣域無線網路接取技術。本論文所討論的無線網狀網路為兩階層式的架構，包含用戶接取端(Access Tier)及骨幹接取端(Backhaul Tier)。用戶接取端主要負責無線網路用戶和骨幹網路間的傳輸；而骨幹接取端則是負責網狀網路節點間的資料傳遞並連接至網際網路。為了達到服務品質保證，我們針對不同的議題進行研究以提升網路品質傳輸。
在用戶接取端，我們提出新的差異性服務模型稱之為per-CLAss Flow fixed proportional differentiated service model (CLAF)，來確保每個服務等級中的資料流都能有固定的頻寬分配比率，根據傳統IEEE 802.11的架構，我們提出可調式競爭時框(contention window)以確保頻寬分配；此外，我們所提出的差異性服務模型更可搭配允入控制(admission control)來支援網路電話等即時應用之服務。
在骨幹接取端，我們研究TCP在多重跳躍無線網路(multi-hop wireless networks)上的行為，清楚定義多重跳躍無線網路中著名的隱藏終端問題(hidden terminal problem)與暴露終端問題(exposed terminal problem)，並利用模擬的方式呈現這兩個問題對於TCP效能的影響。為避免無線網路的傳輸競爭與干擾及考慮到TCP不對稱流量的特性，我們提出分時多工存取排程(spatial TDMA scheduling)來提升TCP的效能。

Wireless mesh networking technology is currently receiving a great deal of attention because it offers a promising solution to the challenges presented by next generation networks. In this dissertation, the Infrastructure/Backbone Wireless Mesh Network with access tier that connects the client wireless device to a mesh node and the backhaul tier that interconnects the mesh nodes to forward traffic to and from wireline Internet entry points or gateway mesh nodes is considered. To fulfill the quality of service guarantee in the two-tier wireless mesh access networks, different issues on the access and backhaul tier are addressed.
In the access tier, we propose a new per-CLAss Flow fixed proportional differentiated service model (CLAF) and a companioning medium access control scheme for multi-service wireless LANs (WLANs), based on the IEEE 802.11 framework. Different from conventional differentiated services, CLAF provides a) policy-based fixed proportional differentiated service; b) such fixed proportional service differentiation is on per-class flow basis; and c) each class contention window size is adjusted to reflect the actual traffic load of the class.
In the backhaul tier, we analyze how the multi-hop hidden terminal and exposed terminal problems affect the TCP throughput performance in multi-hop wireless networks via simulations. It shows that the performance interference due to the hidden and exposed terminal problems between wireless links is location-dependent. Therefore, based on the spatial reuse properties and considering the asymmetric traffic load of TCP connections, we propose spatial TDMA scheduling algorithm to resolve channel access contentions and thus improve the TCP performance in multi-hop wireless networks. The simulation results show that the proposed spatial TDMA scheduling algorithm can achieve better throughput performance. Since there is no channel interference within wireless links, the end-to-end TCP throughput is limited by the available bandwidth as expected.

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