於行動網路上的視訊串流常受到訊號衰減與屏蔽效應的影響。舉例而言，當一輛火車行駛在路線固定的軌道上，訊號將隨著移動路徑而改變，特別是在隧道或地下道等特定地點中。這種劇烈的訊號變化將導致封包的遺失並影響到影片播放品質，若隧道的長度過長，更可能導致行動裝置端串流緩衝資料量(streaming buffer)的不足。因此，我們提出了一個於火車情境下的適地性視訊串流控制機制(Location-Based Video Streaming Control Scheme for Trains)。基於火車具行駛於固定路線等特性，訊號狀況的變化將會呈現特定的模式。我們所提出的LBVS-T機制，可以根據地形環境變化所導致的網路連線中斷情形，調整資料的傳送速率。從效能測試結果可看出，在火車接近隧道、行駛於隧道中以及離開隧道的各個期間，我們所提出的機制可改善串流緩衝資料量用盡的狀況，並且提供較為平順的串流品質。

Video streaming over the wireless mobile network suffers from signal fading and shadowing effects. For instance, when the train is moving in a fixed route over the railway, the signal will vary along the moving route, especially on some specific positions, e.g., tunnels and underground. This serious signal variation results in packets loss and affects the video presentation quality. Furthermore, if the length of the tunnel is too long, the streaming buffer at the client side will have the starvation phenomenon. In this paper, we proposed a video streaming control mechanism called Location-Based Video Streaming Control mechanism for Trains (LBVS-T). Since the characteristics of the train are moving on a fixed route, the signal variation will show a specific pattern. The proposed mechanism can adjust the transmission rate based on the network disruption situation, which is caused by the geographic environment. The performance results demonstrate that, LBVS-T can tackle the buffer starvation problem and have more smooth streaming performance when a train is moving before entering into, inside and just outside tunnels.

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