未來無線網路的目標是以IP通訊協定為基礎提供使用者各種即時的應用，並支援機動性。在網際網路上，即時傳輸通訊協定(Real-time Transport Protocol, RTP)透過UDP/IP能夠傳遞即時資料串流。對應於RTP，即時傳輸控制通訊協定(RTP Control Protocol, RTCP)能監督RTP的連線狀況，適時地回報控制訊息。
傳統上，流量控制會在封包遺失率高的時候降低傳輸率，如此便可以減少網路壅塞，進而降低封包遺失率。另外，重傳和向前錯誤更正(Forward Error Correction)也被提出來恢復遺失的封包。這些方法都是根據有線網路的特性去設計的，並不能完全套用到無線網路端。

另一方面，RTP封包本身也造成了嚴重的標頭浪費。譬如傳遞聲音的封包標頭的部分可能就是聲音訊框的兩倍大小。因此，標頭壓縮的RTP(Compressed RTP, CRTP)就被提出來。它可以將RTP/UDP/IP三層的標頭做壓縮，然後透過下層做點對點的傳輸。然而，無線連結的高錯誤率會造成許多封包因為無法正確解壓縮而丟棄，使得播放品質大受影響。

由於無線網路上位元錯誤率高、頻寬較少，使用者也可能到處地移動，因此RTP必須做一番改進來適應無線網路的特性。我們研究的目標就是以重傳為基礎來改善CRTP。在無線網路上，我們要用最少的頻寬來成功傳輸最多的封包，即使無線連結是在高位元錯誤率或使用者移動到其他細胞的情況下，我們所提的方法也都能夠改善無線頻寬的效率以及即時多媒體播放的品質。

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