This paper examines the impact of different physical modes on network QoS parameters such as throughput, bit error rate, and retransmission delays. An efficient technique for the transmission of MPEG-2 bit stream over HIPERLAN/2 networks is presented that exploits the hierarchical structure of the MPEG-2 bit stream. We show that for a given video bit stream use of multiple modulation schemes chosen based on the characteristics of underlying video data yields superior throughput and better picture quality in terms of PSNR.