Patent ID: 6252885
Filing Date: 2001-06-26
Classification: H04H

Abstract:
A communication method between a center device and a plurality of terminal devices connected by a network, said method comprising the steps of:(a) transmitting, from said center device to said terminal devices, cyclically a group of downstream timeslots each of which is distinctive from each other, each downstream timeslot being a first unit of data communication and each of said downstream timeslots including upstream timeslot occupancy information indicating the vacancy of an upstream timeslot corresponding to the downstream timeslot if the upstream timeslot is vacant, assignment information of the upstream timeslot indicating the one of the plurality of terminals which is being assigned to the upstream timeslot when the upstream timeslot is occupied, and downstream data, said transmitting step (a) transmitting the upstream timeslot occupancy information regardless of whether the upstream timeslot is vacant or occupied;(b) checking, at the terminal device, the upstream timeslot occupancy information in the downstream timeslots to detect a downstream timeslot including the upstream timeslot occupancy information of a vacant state;(c) sending timeslot use request, from said terminal device to said center device, by an upstream timeslot specified by the upstream timeslot occupancy information of the vacant state at a timing corresponding to the downstream timeslot detected in the step (b), each upstream timeslot being a second unit of data communication;(d) receiving, at said center device, the upstream timeslot sent in the step (c), and sending a downstream timeslot, to the terminal devices, which includes the assignment information indicating that the timeslot is assigned to the terminal device which has sent the timeslot use request and the upstream timeslot occupancy information of the occupied state;(e) detecting, at said terminal device, the assignment information in the downstream timeslots and, if the assignment information indicating the assignment of the upstream timeslot to the terminal device, sending upstream data using the upstream timeslot assigned to the terminal device, wherein the address of the downstream data included in the downstream timeslot is irrelevant to the address of the terminal devices.