Data transmission in a point-to multipoint network

摘要

A point to multipoint network includes a central node and a plurality of terminals connected to the central node via a transmission medium. The central node transmits frames of data downstream to said terminals in timeslots and said terminals transmit data packets upstream in timeslots allocated by transmission permits contained in the downstream data. When transmitting a transmission permit to a terminal the central node reserves a time period in the future downstream data stream during which data destined for the terminal will be blocked from transmission. The reserved time period commences at a time location in the future data stream and has a duration, such that data transmitted to the terminal in a timeslot immediately following the reserved time period will arrive at said terminal after the same has terminated transmission of data in response to the permit. This reliably ensures that a terminal will not transmit and receive data simultaneously. Thus interference between a transmitter and receiver in a terminal is avoided without recourse to costly filter circuitry.