- 期刊
高鐵列車內使用AL-FEC之WiFi多播串流服務
WiFi Multicast Streaming Using AL-FEC Inside the Trains of High-speed Rails
摘要
用以傳送大範圍的多媒體廣播之行動電視系統，如DVB-H以及3GPP MBMS （Multimedia Broadcast Multicast Service，多媒體廣播多播服務），為了減少封包掉落的機率，都已經使用AL-FEG（Application-Layer FEC，應用層前向糾錯技術）來保護串流或是傳送檔案服務。然而，在WiFi multicast環境下使用AL-FEG仍然不是一個被充分地研究的方法。因為對multicast服務而言，確保頻寬穩定在無線網路上實作遠比在傳統的行動電視系統上困難的多。本文使用系統化猛禽碼（systematic Raptor code）以及IETF FEG框架來取代其他的回饋及重傳的機制，結果顯示兩者可進一步保護在高鐵車廂內使用WiFi multicast傳送的RTP封包，以提供車廂內高品質的multicast影音串流服務。
並列摘要
AL-FEC (Application-Layer FEC) is already in used for protecting streaming and file delivery services against packet losses in the field of wide-area multimedia broadcasting, such as in DVB-H and 3GPP MBMS (Multimedia Broadcast Multicast Service) mobile TV systems. However, it is still not a well-studied approach for applying AL-FEC to WiFi multicast since guaranteed bandwidth for a multicast service is more difficult to be allocated in a WiFi network in comparison to traditional mobile TV systems. In this paper, we show our experiences of using an AL-FEC code; i.e. the systematic Raptor code as well the IETF FEC Framework to further protect the RTP packets delivered over WiFi multicast carriers inside the cars of a train for high-speed rails, instead of using any feedback and retransmission mechanisms.