Performance evaluation of video streaming over ad hoc networks using flat and hierarchical routing protocols

A performance evaluation of real time services (such as video streaming) over mobile ad-hoc networks using both hierarchical and flat routing protocols is shown in this paper. A variety of workload and scenarios, as characterized by mobility, load and size of the ad hoc network have been simulated using NS-2. We use OLSR (Optimized Link State Protocol) as the flat routing protocol and our own implementation of HOLSR (Hierarchical OLSR)-which uses HNA (Host and Network Association) messages-as the hierarchical one, modifying other previous HOLSR version and maintaining the maximum compatibility with the flat OLSR. We carry out a complete comparison between these protocols focused on video evaluation. The simulation lets us compare the quality of service (QoS) of the video streaming paying attention to objective parameters (PSNR, packet delivery ratio, packet delay and interruptions). Some drawbacks of the hierarchical environment are also analyzed, as the link load between cluster heads and the lack of QoS-state-aware in HOLSR design. Quantitative results indicate that the protocol overhead is reduced (more than 40% in larger networks) and the video quality is improved (from 1 to 6 dB in certain cases) using hierarchical protocols.