適用於異質性無線網路之錯誤可調性TCP

• Main Authors: 張碩瀚, Chang,Sol-Han
• Language: 英文
• Published: 國立政治大學
• Subjects: 異質性無線網路; 多媒體服務; TCP; Heterogeneous wireless networks; Congestion Avoidance Algorithm; Streaming service
• Online Access: http://thesis.lib.nccu.edu.tw/cgi-bin/cdrfb3/gsweb.cgi?o=dstdcdr&i=sid=%22G0093753018%22.

現今我們所住的世界不再只是一個單純的有線網路，隨著WLAN的無線區域網路的存取點越來越普遍，每個家庭使用有線網路做為後端網路然後使用無線區域網路的存取點作為最後一哩的情況也隨著變的常見了，所以現在的網路世界不再只是一個單純的有線網路而是一個有線跨無線的異質性無線網路了，TCP一個我們所常用的傳輸層的協定當遇到異質性無線網路時已經被證實會對封包遺失的原因有誤判，在無線傳輸時封包遺失的理由包括訊號品質不好以及用戶端之間在無線介質中的競爭，因此我們設計了一個具有跨層考量的EATCP-Assisted模組來幫助傳送端收集媒體存取控制層的資訊並使的傳送端在調整競爭視窗上面更有效率，在EATCP中有兩大部分：第一部份是估算階段，第二階段就是EATCP的擁塞控制機制，藉由EATCP-Assisted模組所收集到的wirelessRTT以及utilization我們可以有效的估算出wiredBW以及wirelessBW，並藉由這兩個參數我們可以準確的將封包遺失的原因從頻道衰減以及用戶端之間的競爭中分別出來，因此一個適當的競爭視窗就可以藉由這些資訊來調整出來。 === Recently, with the growth of WLAN, the world we live today is no longer a pure wired network, it’s a heterogeneous wireless network. The TCP that we commonly used has been proven to have misjudgements of packet loss in heterogeneous wireless networks. We design a cross-layer architecture called EATCP-Assisted module to help the sender collect MAC layer information, and adjust the congestion window more efficiently. In EATCP, there are two important parts: the first is estimation phase; the second is congestion control algorithm. By collecting the wirelessRTT, and utilization we can estimate the wiredBW and wirelessBW. The EATCP will distinguish the causes of packet loss from network congestion, channel fading, or contention between wireless clients. Thus, appropriate congestion window adjustment can be done accordingly. The simulation results show that our EATCP outperforms other versions of TCP.