US 6,643,815 B1Granted

Data compression over communications links which are exposed to occasional errors

AssigneeInternational Business Machines Corporation

InventorsGordon Taylor Davis, Malcolm Scott Ware, Charles Robert Young

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Abstract

Re-synchronization of sets of transmit and receive state variables in a communication system is achieved when an error is detected, without disrupting the connection. Each of first and second transceivers, connected by a communications channel, have a common set of transmit and receive state variables supporting a data encoding algorithm function. The transmitter of one of the first and second transceivers fist encodes data to be transmitted and updates the transmit state variables according to the data encoding algorithm and the receiver of the receiving transceiver validates whether or not each data block has been received correctly. During the process of decoding the data, the receive state variables are updated according to the same algorithm used to update the transmit state variables, thereby keeping the two sets of state variables in synchronism with each other. When an error is detected, re-synchronization occurs by switching to transparent mode in the direction of communication in which the error occurred and resetting the corresponding transmit and receive sets of state variables.

Claims23

Dependent claims

A data communication system which allows re-synchronization when an error is detected, without disrupting the connection, comprising:

first and second transceivers connected by a communications channel, each of said transceivers having a common set of transmit and receive state variables supporting encoding and decoding functions, respectively, of a data compression algorithm;
a transmitter of one of the first and second transceivers first encoding data to be transmitted and updating the transmit state variables according to said encoding function of said data compression algorithm and generating a syndrome or signature for use by an error detection mechanism for each data block to be transmitted, the transmitter then transmitting the data across the communications channel to a receiver of the other of the first and second transceivers;
and
the receiver of the receiving transceiver converting the received signal into a bit stream and processing the bit stream by an error detection mechanism validating whether or not each data block has been received correctly, and passing the data blocks passed through the decoding function of said data compression algorithm, which converts the data to correspond to its original form, and during the process of decoding the data, updating the receive state variables of said data compression algorithm, said data compression algorithm being the same algorithm used to update the transmit state variables, thereby keeping the two sets of state variables in synchronism with each other.

1 more element

In a data communication system, a method of re-synchronization when an error is detected, without disrupting the connection comprising the steps of:

encoding data to be transmitted by a transmitter of one of first and second transceivers using an encoding function of a data compression algorithm;
updating a set of transmit state variables according to the encoding function of said data compression algorithm;
generating a syndrome or signature for use by an error detection mechanism for each data block to be transmitted and transmitting the data across a communications channel to a receiver of the other of the first and second transceivers;
receiving the data transmitted across the communications channel by the receiver of the other of the first and second transceivers;
converting the received signal into a bit stream;
processing the bit stream by an error detection function to validate whether or not each data block has been received correctly;
passing the data blocks through a decoding function of said data compression algorithm, which converts the data to correspond to its original form;
and
during the process of decoding the data, updating a set of receive state variables according to a decoding function of said data compression algorithm, said data compression algorithm being the same algorithm used to update the set of transmit state variables, thereby keeping the two sets of state variables in synchronism with each other.

6 more elements

Dependencies are inferred from the claim text.