طرح تبعیض خسارت بین لایه ای برای DCCP بر روی شبکه بی سیم ☆

DCCP (Datagram Congestion Control Protocol) is a transport layer protocol that provides congestion control for unreliable data transmission. The congestion control mechanism embedded in DCCP adjusts the packet sending rate according to network condition. However, DCCP does not discriminate congestion losses and wireless link errors resulted from fading and thus it leads to unnecessary rate adjustment. In this paper, we proposed a mechanism to enhance bandwidth utilization of DCCP over wireless network. We employed a cross-layer loss discrimination scheme to distinguish congestion loss and fading loss. The cross-layer based mechanism detects frame loss in the data link layer in real-time to infer the actual fading loss rate. Thereafter, the fading loss can be excluded from the packet loss observed in the transport layer. Once the accurate congestion loss rate is calculated, the sender can make appropriate adjustment on the transmission rate that reflects the current congestion state along the transmitting path using the DCCP rate control procedure. Simulation results show that DCCP with our proposed CCID 3 rate control scheme can discriminate fading loss and achieve from 4.7% to 15.5% improvement on transmission throughput when the fading loss rate varies from 5% to 15% in wireless network.