An access protocol to support multimedia traffic over hybrid fiber/coax systems

Hybrid fiber/coax plant is being widely deployed to deliver broadband interactive services to the home. Many of these services require a two-way high-speed channel, for example, extending the office LAN into the home. This is a challenging problem over HFC because most of the plant has only a small fraction of the bandwidth allocated to the upstream path, it is a noisy path and it is not possible to sense the medium prior to transmitting. For these reasons a protocol tuned to the medium is necessary. The centralized priority reservation (CPR) protocol is specifically designed for HFC plant with a primary goal of keeping the protocol within the station as simple as possible, consistent with efficient use of the channel. The basic CPR protocol has been described previously. In this paper we describe the application of CPR to the transmission of multimedia type traffic and the performance that is obtained. It supports multiple levels of priority in the transmission of asynchronous data with fine control over the level of priority. It also supports synchronous streams of information. Channel capacity not required by the streams is available to the asynchronous data