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Abstract

A method for allowing upstream channels having the same multiplexing type but different symbol rates or the same symbol rates but different multiplexing types to be transmitted on the same frequency band without interfering with each other. In particular, a method for allowing DOCSIS 1.0 TDMA only cable modems to coexist on a digital data delivery distributed system with advanced PHY TDMA or SCDMA mode cable modems without the need for modification of the DOCSIS 1.0 cable modems or the need for the DOCSIS 1.0 modems to transmit on a different frequency. The method comprises: using a plurality of upstream channel descriptor messages transmitted from said central modem to said distributed modems to define a plurality of different upstream logical channels sharing the same frequency band, each said logical channel having either a different symbol rate but the same multiplexing type or the same multiplexing type but a different symbol rate, said upstream channel descriptor messages assigning each of said distributed modems to logical channels appropriate to the symbol rate and modulation type of said distributed modem; and, scheduling transmission bursts on each said logical channel by transmitting a bandwidth award and scheduling message for each logical channel each of which defines and controls which distributed modems on the logical channel to which the bandwidth award and scheduling message can transmit and when they can transmit, said bandwidth award and scheduling messages being coordinated by said central modem so that there is never any overlap in time between transmission bursts on different logical channels sharing the same frequency band.

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First Claim