| 摘要: | ZigBee(蜂訊)是一種短距離、低傳輸速率、收發少量資料、 低耗電 、容易布建網路的無線傳輸技術，由於其多點通訊造成通訊負擔，因此需要有效率的使用有限的電量。
動態源路由協定(Dynamic Source Routing, DSR)主要是為了能夠延長整個感測器節點的生存時間，因此不採取每次資料傳輸時才廣播尋找傳輸路徑之機制，而採取路由快取(Route Cache)方式記錄路徑。
此機制在執行路由維護(Route Maintenance)過程中，發生路由錯誤(Route Error, RERR)時，則使路由快取選取路徑，可能發生選取到舊有路徑(Stale Route)，但因原本路徑上之節點移動，造成路徑斷裂(Route breakage)，由於Stale Route之Route breakage問題導致資料傳輸失敗、Route Cache儲存空間浪費、資料傳輸必須重新選定路徑重傳等問題，以上問題導致感測節點電量之耗損失效，導致整體網路連通性降低，另外因要選定路徑重傳也增加End to End Delay。所以為了解決Stale Route造成的問題，需要有效區分Stale Route以及fresh route。
本論文提出使用馬可夫鏈(Markov chain)，將緩衝區、封包遺失、傳輸範圍外為參數使用當前其節點time out的機率，推測未來time out的機率進而達成到期提醒，達到有效管理路由快取，因而可以有效減少封包遺失，End to End Delay，提高DSR執行效能。
Simply ZigBee is a short-range, low transmission rate, receive a small amount of data, low power consumption, easy provisioning of wireless network transmission technology. because of its multi-point communications cause communication burden, thus the need for efficient use of limited power. Dynamic source routing(DSR) designed primarily to be able to prolong the survival time of the whole sensor nodes, perform Route Maintenance process occurs when the Route Error, Route Cache is used to select a path that may occur selected to Stale Route, causing Route breakage, so in order to solve this issue needs to effectively distinguish Stale Route and fresh route.
In this thesis, we propose use Markov chain, the buffer, packet loss, transmission out of range ,three parameters to prediction the time out of their nodes. Achieve effective management of Route Cache, can effectively reduce packet loss, End to End Delay and improved DSR performance. |
