Hybrid error recovery protocol for video streaming in vehicle ad hoc networks

Recently, video streaming in Vehicular Ad hoc NETworks (VANETs) is considered as one of the most important challenge in vehicular communication because of the high packet loss rate and the increased transmission delay due to the highly dynamic of VANET topology. This specificity makes difficult to apply the conventional transport protocols such as UDP and TCP to video streaming over VANET. To deal with these limits and to ensure a high video quality at the end receiver, we propose in this paper a Hybrid Error Recovery Protocol (HERP) for video streaming in VANETs. The proposed protocol integrates the Sub-Packet Forward Correction (SPFEC) mechanism to recover the uniform transmission errors and the retransmission technique to recover burst errors mainly due to the network congestion and route disconnection. In order to avoid the network overload and to reduce the transmission delay, HERP adapts dynamically the redundancy rate, retransmission limit and transmission rate according to the network condition measured by the Bit Error Rate and the network load indicated by queue length of intermediate vehicles. HERP uses the reporting technique to control the network condition and the network load. To improve the video streaming quality, HERP suggests an unequal protection of video frames type (i.e. I, P, B frames). The experimental results show that HERP achieves significant improvements of transmitted video compared to native UDP protocol and UDP based on SPFEC.