US 5,177,739 AGranted

Multiport - multipoint digital data service

AssigneeRacal Data Communications Inc.

InventorsRogelio J. Basnuevo, Jose R. Diaz, Norman J. Donaghue, Jorge A. Valdes, Stephen J. Winter

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Abstract

In a Digital Data System (DDS) a method and apparatus for providing multipoint multiport service. Differences in time delays through the network are compensated by an alignment training wherein the delays from each remote station are measured at a Central station. The Central station determines how much delay to insert at each remote station and then instructs the remote stations to insert the delays. This allows all inbound data to be aligned in time so that when the data are combined within the network by the Multipoint Junction Units (MJU) data errors are not produced. Aligned frames are combined in the MJU operating in data mode in a logical AND operation so that marks transmitted by inactive ports are combined with data from active ports to produce a composite signal which is passed to the Central DSU.

Claims40

Dependent claims

A method for use in a digital data network wherein at least one digital bridging device combines digital data bits from a plurality of remote stations into a composite signal for transmission to a central station, comprising the steps of:

providing said central station with a plurality of central data ports;
providing each of said remote stations with at least one remote data port;
there being at least one said remote data port for receiving said data bits for transmission to each one of said central data ports;
at least two of said remote data ports being operable for receiving said data bits for transmission to a same one of said central data ports;
arranging at said remote stations said data bits from said remote ports into reoccurring fixed size frames with each one of said frames having a plurality of time slots;
there being at least one of said time slots assigned to transmit said data bits to each of said central ports;
said assignment of time slots to said central ports being the same at each of said remote stations;
initially aligning said frames from different said remote stations by adjusting transmission times from at least one of said remote stations so as to cause said frames from said different remote stations to arrive at said central station simultaneously;
transmitting said aligned frames from said remote stations to said central station;
after initially aligning said frames, monitoring to determine if said inbound frames from said remote stations remain in time alignment;
and
if said inbound frames from said remote stations do not remain in time alignment, further aligning said frames from different said remote stations by adjusting transmission times from at least one of said remote stations so as to again cause said frames from said different remote stations to arrive at said central station simultaneously.

9 more elements

A digital data communication system for a digital network wherein digital data bits are transported between a plurality of locations, each said data bit lasting for a predetermined bit time, comprising:

a central station coupled to said network, said central station including a plurality of central data ports, each of said central data ports being associated with a different one of a plurality of independent data applications:
a plurality of remote stations coupled to said network, each of said remote stations having at least one remote data port associated with one of said data applications, the number of said remote data ports being greater than the number of said central data ports, there being a least one of said remote data ports associated with each of said data applications;
said remote stations each including framing means for arranging said data bits from said at least one remote data port into a plurality of time-division multiplexed frames for transmission through said digital network to said central station, each of said frames having a plurality of time slots with at least one of said time slots being assigned to each of said data applications;
alignment means for initially aligning said frames transmitted by said plurality of remote stations so to cause said frames to arrive at said central station simultaneously by adjusting transmission times from at least one of said remote stations by an integer number of said bit times;
means for monitoring alignment of said frames to determine if said frames from said remote stations remain in time alignment after initial alignment of said frames;
and
said alignment means, if said frames from said remote stations do not remain in time alignment, being operable for further alignment of said frames from different said remote stations by again adjusting transmission times from at least one of said remote stations so as to cause said frames from said different remote stations to arrive at said central station simultaneously.

4 more elements

Dependencies are inferred from the claim text.