無線網路廣泛的使用在人群之中像是有基地台式的無線網路(infrastructure network) 或是無基地台式的無線網路(ad hoc network). 有基地台式的無線網路需要固定的基地台來作為行動裝置與有線固網的連結.兩個行動裝置必須透過基地台跟骨幹網路才能夠做溝通傳輸.ad hoc network中的任何行動裝置可以互相的通訊不需要任何固定式的基地台的架設. ad hoc network通常可以使用在戰地或者是荒野那些沒有固定式基地台的地區. 下一代的ad hoc network需要在任何時間任何地點提供給使用者一個到處存在的傳輸媒介.合適的頻寬與穩定的網路是必須的.為了要提供高頻寬,重複使用資源與避免碰撞是需要被重視的議題.另外ad hoc network使用在特殊的環境沒有電源的提供.如何能夠節省電源以使得網路趨於穩定.多媒體被廣泛的使用像是語音或是影像的傳輸在現在的網路上. 多媒體需要足夠的頻寬跟一個有服務品質保證的環境.以上的個點皆是下一代ad hoc network 需要注重的地方. 在這篇論文中,我們提出了一個整合性得架構(PMQ)在ad hoc network 底下支援多媒體的傳輸.PMQ 系統在MAC 層使用Multi-channel MAC protocol.在連結層使用有優先考量的排程.加上具有服務品質保證的路由機制以達成一個多媒體的ad hoc network.我們使用IEEE 802.11a來架構 ad hoc network因為IEEE 802.11a有足夠的頻寬可以提供多媒體的傳輸.Multi-channel MAC protocol是CSMA/CA的延伸可以減少發生碰撞的機率並且提供較高的頻寬.省電的機制在ad hoc network也是很重要的一部分所以在PMQ的系統裡我們也提出了跟IEEE 802.11標準相對的省電模式.並且路由機制藉由虛擬線路提供合適的頻寬以及可容忍的延遲.總而言之PMQ 系統提供了一個具有服務品質保證的多媒體ad hoc network. Wireless networks have been widely deployed pervasively around human being, either by infrastructure wireless networks or ad hoc networks. Infrastructure wireless networks require fixed base stations to interconnect mobile devices with backbone network services. The successful communications between two mobile devices will rely on the assistance of base stations. In addition to Infrastructure wireless network, ad hoc network is a collection of mobile devices that could communicate with each other without any fixed infrastructure. It could be applied in battlefield and wasteland that is without any fixed wire backbone network. The new generation ad hoc network will compliment mobile users with ubiquitous multimedia communications anywhere and anytime. Key issues, such as adequate bandwidth allocation, efficient radio resource management and effective power utilization will determine corresponding perceived quality. To satisfy high bandwidth demands, channel reusing and collision avoidance demonstrate the enhancement possibility for ad hoc network. For sustaining the longer lifetime of mobile nodes to further improve the network connectivity, an intelligent power saving scheme is required. To realize ad hoc multimedia connections, such as voice and video communication, a high performance and QoS guaranteed network environment is expected. This thesis proposes an integrated PMQ (Power-saving Multi-channel MAC protocol with QoS reservation for multimedia ad hoc networks) architecture to support QoS for multimedia applications in ad hoc network. PMQ system utilizes an advanced multi-channel medium access method, priority queue, and a QoS routing scheme with virtual circuit to ensure QoS in ad hoc network. A multi-carrier system, IEEE 802.11a is adopted to construct ad hoc network due to higher bandwidth and channel orthogonal property. The proposed multi-channel MAC enhanced from CSMA could decrease collision probability and provide high performance. Besides, MAC of PMQ also provides a power-saving approach particularly for ad hoc mobile nodes. Via QoS routing of PMQ, it will provide virtual pipes for multimedia applications in order to guarantee bandwidth and delay time.
