Data transmission using arithmetic coding based continuous error detection

Apparatus for data transmission using automatic repeat request to obtain continuous error detection, comprising:

• means to partition data into packets and introduce a forbidden symbol which is not intended to be transmitted;
• an arithmetic encoder to encode the data in packets and transmit them;
• means to decode data received at a receiver;
• means to identify an error within a packet during transmission based on whether a forbidden symbol is decoded;
• and
• means to request retransfer of only a portion of the packet with the error, which portion occurs after a location of the error, whereby a need to retransmit an entire data packet wherein an error has occurred is obviated.

A method of transmitting data from a transmitter to a receiver using an automatic repeat request (ARQ) to obtain continuous error detection, comprising the steps of:

• partitioning the data into packets and introducing into process of encoding the partitioned data a forbidden symbol which is not intended to be normally transmitted, nor decoded at the receiver, receiving the transmitted data and checking to see if a decoded version of the forbidden symbol exists, indicating a transmission error;
• deciding in which data packet said transmission error occurred;
• and
• initiating retransmission of a portion of the data packet where said error occurred, said portion being located after occurrence of the error whereby data transmission is rendered more efficient.

In image and data communications, of the type using automatic repeat request (ARQ) protocols wherein data is parsed into data blocks for transmission and wherein those blocks which are deemed to contain errors are required to be retransmitted, an improved method for error detection comprising:

• using arithmetic coding for coding data, and introducing into the data, a forbidden symbol which is never encoded, said forbidden symbol occupying a controllable amount of coding space;
• using an existing arithmetic coder, if any, for both entropy coding and continuous error detection;
• ascertaining, if said forbidden symbol is decoded;
• and
• controlling a time interval from when an error occurs to when aforbidden symbol is decoded, said controlling being effected by manipulating said coding space which said forbidden symbol occupies, thus controlling a number of bits which need to be retransmitted, whereby error detection is continually done without having to retransmit entire data blocks in which an error is detected, and only that portion of a data block which occurs after an error location needs to be retransmitted.