Efficient multimedia transmission in wireless sensor networks

Real-time multimedia data such as video are usually loss-tolerant but require timely delivery in order to be useful to the application. Loss recovery through the retransmission of lost data may introduce unacceptable delays, which is the reason why these data types are usually delivered with no transport layer reliability, using erasure coding and similar techniques to maximize data recovery at the receiver. However, in Wireless Multimedia Sensor Networks (WMSNs), these mechanisms are not enough to provide an acceptable image quality and, thus, reliable transport protocols adapted to these requirements are needed. This paper presents some mechanisms to improve multimedia transmissions in WMSNs when reliable transport layer protocols are used. They consist of assigning a budget of time for the sending of certain amount of information and estimating if the channel conditions allow to complete the transmission or not. If it is not likely to complete it, then the transmission is stopped, thus saving important energy resources in the sensors. We evaluate this approach by modifying the behavior of a previously proposed reliable transport protocol (DTSN). Our proposal, M-DTSN, improves DTSN flexibility by managing the trade-off between media quality and timely delivery for real-time multimedia data with some degree of loss-tolerance. The simulation results demonstrate that the advantages of M-DTSN for the transmission of multimedia data are quite significant when compared with the original DTSN protocol.