chapter  15
IPTV and WiMAX
Pages 32

TV services have traditionally been delivered to homes using cable TV or DTH or terrestrial broadcasting technologies. All the modes of delivery are based on the availability of a fixed bandwidth (e.g., 5-8 MHz for analog transmissions) or a guaranteed and sustained bit rate (e.g., 2-6 Mbps for MPEG-2 video). These traditional technologies have been very successful in delivering audio and video to the homes, and quality is rarely an issue. On the other hand, the internet has also been used to carry streaming video on a best-effort basis largely for desktop applications. The “internet video” is delivered by streaming using the RTP/RTSP protocol for unicast transmissions. The RTSP protocol was designed for providing minimum latency, which apparently was the fastest way to deliver video over unreliable networks. Because of the non-availability of guaranteed throughput and latency, internet video has traditionally been characterized by small video windows (e.g., QCIF resolution), jerky video, or dropped frames caused by the inability of the network to handle video at sustained bit rates.