Modulation level allocation for MGS streaming over a multihop wireless channel

This article introduces a method for efficiently transmitting medium grain scalable video packets over a transmission path consisting of multiple wireless links. Medium grain scalability provides bit rate adaptation according to the available bit rate by dropping a number of video packets in the compressed bit stream. In other words, rate-distortion control can be achieved by means of packet transmission control. The available bit rate and the spectral efficiency are determined by the bandwidth and the modulation level, respectively. Accordingly, the number of packets available for transmission is affected by the modulation level of the packets. However, if we consider modulation levels with higher spectral efficiency in order to increase the number of packets and reduce the expected video distortion, the packet error rate of the transmitted packets can also be increased because the spectrally efficient modulation levels are sensitive to channel noise. This is another reason for the increment in expected video distortion, because the erroneous received packets cannot be used for video reconstruction. Therefore, this article considers the minimization of expected video distortion by the optimization of two factors-packet extraction for transmission and modulation level allocation for the extracted packets. Packet extraction is optimized for the path between the source and destination nodes, whereas the modulation level for each extracted packet is optimized for each link along the transmission path.