US 5,003,534 A · Link utilization control mechanism for demand assignment satellite communications network

Abstract

A link utilization control mechanism for a demand assignment satellite communication network employs a modified point-to-point communications protocol (X.25) in order to simulate point-to-point communication ports and thereby interface what is effectively a multidrop network with point-to-point landlink communication resources. Through an acknowledgement reservation mecahsnism the return link channel is subdivided into interleaved data and (preassigned) acknowledgement time slots, in order to substantially obviate ovrhead and throughput penalties encountered in the use of large data packets to transmit reduced size acknowledgement messages. In addition, the normal contention mode of operation of the return link is augmented with a data time slot reservation mechanism through which, during periods of increased message input density at a remote station, transmission throughput is facilitated, so that congestion at the remote station is reduced.

Claims11

Dependent claims

For use with a communication system having a master station and a plurality of remote stations which communicate with one another over a communications link, each of said remote stations having the capability of transmitting messages over said communications link to said master station on a demand basis, and wherein the successful transmission of a message from said master station to a remote station and receipt thereof by a destination device is acknowledged by the return of an acknowledgement message from said remote station to said master station, a method of controlling the return of acknowledgment messages from a remote station to a master station comprising the steps of:

at said master station,
(a) transmitting, as part of a message to a remote station, the identification of a prescribed time slot, relative to a reference time occurrence, within which an acknowledgement message is to be returned by said remote station;
and
at a remote station,
(b) monitoring said communications link for a message transmitted to that remote station from said master station and, in response to the successful receipt by a destination device of a message from said master station, returning an acknowledgement message to said master station during a time slot as identified as part of the received message.

2 more elements

For use in a data communications network in which digital information packet-containing messages are conveyed between a first station and a plurality of second stations remote from said first station, said first station containing a packet switch having a first port, into which outgoing messages from a plurality of first terminal devices for transmission to second terminal devices at said second stations are coupled and from which incoming messages from second terminal devices at said second stations are output to said first terminal devices, and a second port through which said outgoing messages are coupled to a first communication channel for transmission to each of said second stations and through which said incoming messages are coupled from a second communication channel used by each of said second devices, and wherein messages, as supplied by a second terminal device for transmission from its associated second station to said first station, are formatted in accordance with a point-to-point communication protocol for controlling communications between said associated second station and said first station, a method of controllably enabling said second communications channel to effectively simulate point-to-point communications from each of said second stations to said first station comprising the steps of:

(a) at a second station, from which a message from an associated second terminal device is to be transmitted to said first station for delivery to a first terminal device coupled thereto, incorporating, into the point-to-point communication protocol format of said message, an identification code that identifies said second station and transmitting said message in said point-to-point communication protocol format over said second communication channel to said first station;
(b) at said first station, receiving the message transmitted from said second station in step (a) and coupling the received message to said second point of said packet switch;
(c) storing the received message that has been coupled to said second port of said packet switch in a storage location the identification of which is designated in accordance with the identification code of said second station contained within the received message;
and
(c) outputting, from said storage location within said packet switch, said stored message, absent said identification code, via said first port to a first terminal device.

2 more elements

For use with a communication system having a master station and a plurality of remote stations which communicate with one another over a communications link, each of said remote stations having the capability of transmitting messages over said communications link to said master station on a demand basis, and wherein the successful transmission of a message from said master station to a remote station and receipt thereof by a destination device is acknowledged by the return of an acknowledgement message from said remote station to said master station, an arrangement for controlling the return of acknowledgment messages from a remote station to a master station comprising:

first means, at said master station, for transmitting, as part of a message to a remote station, the identification of a prescribed time slot, relative to a reference time occurrence, within which an acknowledgement message is to be returned by said remote station;
and
second means, at a remote station, for monitoring said communications link for a message transmitted to that remote station from said master station and, in response to the successful receipt by a destination device of a message from said master station, returning an acknowledgement message to said master station during a time slot as identified as part of the received message.

For use in a data communications network in which digital information packet-containing messages are conveyed between a first station and a plurality of second stations remote from said first station, said first station containing a packet switch having a first port, into which outgoing messages from a plurality of first terminal devices for transmission to second terminal devices at said second stations are coupled and from which incoming messages from second terminal devices at said second stations are output to said first terminal devices, and a second port through which said outgoing messages are coupled to a first communication channel for transmission to each of said second stations and through which said incoming messages are coupled from a second communication channel used by each of said second devices, and wherein messages, as supplied by a second terminal device for transmission from its associated second station to said first station, are formatted in accordance with a point-to-point communication protocol for controlling communications between said associated second station and said first station, an arrangement for controllably enabling said second communications channel to effectively simulate point-to-point communications from each of said second stations to said first station comprising:

first means, located at a second station from which a message from an associated second terminal device is to be transmitted to said first station for delivery to a first terminal device coupled thereto, for incorporating, into the point-to-point communication protocol format of said message, an identification code that identifies said second station and causing said message to be transmitted in said point-to-point communication protocol format over said second communication channel to said first station;
second means, located at said first station, for receiving the message transmitted from said second station as a result of the operation of said first means, and coupling the received message to said second port of said packet switch;
third means, coupled with said second means and the ports of said packet switch, for storing the received message that has been coupled to said second port of said packet switch in a storage location thereof the identification of which is designated in accordance with the identification code of said second station contained within the received message;
and
fourth means, coupled with said third means, for outputting, from said storage location of said third means, said stored message, absent said identification code, via said first port to a first terminal device.

2 more elements

Dependencies are inferred from the claim text.

Link utilization control mechanism for demand assignment satellite communications network

Life of this patent

Link utilization control mechanism for demand assignment satellite communications network

Life of this patent

Abstract

Claims11