PCUP: pipelined cyclic upstream protocol over hybrid fiber coax

In order to bring the NII (National Information Infrastructure) into the home, the community cable TV networks have to be reengineered to support two-way interactive services. The authors propose the PCUP (pipelined cyclic upstream protocol) as the upstream MAC (medium access control) protocol for the HFC (hybrid fiber coax) community access network. The PCUP is designed with the intention of pipelining the upstream channel. This is achieved by proper station positioning, which measures the station propagation offset from the headend, and transmission scheduling which assigns each station a transmission starting time and duration in a cycle. By taking into account the propagation offsets and transmission lines, transmitted cells can appear back-to-back (i.e., pipelined) at the headend. Since only the active stations are scheduled to transmit in a cycle, a membership control mechanism, which runs a contention-based tree walk algorithm, is executed periodically to allow the stations to join or leave. The authors also compare the PCUP with various schemes proposed to the IEEE 802.14 committee.