In method of communicating over a channel group of a communication system wherein a central station transmits to a plurality of terminals over a forward channel, and transmissions by at least one of the plurality of terminals to the central station occur over a return channel of the channel group, a method comprising the step of transmitting by the at least one of the plurality of terminals data to the central station at a data rate that is automatically set by a network management message received over the forward channel by the at least one of the plurality of terminals from the central station;
- wherein the data includes a return channel descriptor packet (RCDP) describing slot allocations of the return channels of a channel group that are in-use, and
- wherein as a number of the at least one of the plurality of return channels in-use in the channel group vary based on traffic conditions in the channel group, a length of the RCDP also varies.