High throughput communication system

A receiver apparatus in a communications system, said receiver apparatus comprising:

• (a) one or more variable-length decoders configured for receiving a variable-length code where variable-length codewords are comprised of an initial transmission sequence of length 1 symbols by itself, or together with a set of up to m−1 increments, where m is an integer greater than one, all increments having the same length Δ, such that if said initial transmission and said increments were transmitted based on non-active ACK/NACK feedback, said variable-length code would approach capacity by exceeding a specified percentage of Shannon capacity of a specified point-to-point channel;
• (b) wherein said variable-length decoders are configured for performing multiple decoding attempts, in which each successive attempt utilizes as its input an input sequence of a previous attempt plus one or more additional increments;
• (c) wherein said one or more variable-length decoders is configured for producing for each attempt either a decoded k-bit message or an indication that no decoded k-bit message is available for that attempt;
• and
• (d) an incremental redundancy decoder configured for receiving as input (d)(i) received symbols corresponding to a common pool of redundancy produced by an incremental redundancy encoder, and (d)(ii) increments produced by already-decoded k-bit messages, and said incremental redundancy decoder is configured for producing output increments for use by said variable-length decoders;
• (e) wherein said one or more variable-length decoders is configured to first attempt decoding of said plurality of L initial transmissions, each corresponding to a k-bit message, which are transmitted over a channel between the transmitter and the receiver, and continue until decoding is successful or no more increments are available;
• (f) wherein said one or more variable-length decoders is configured for continuing to attempt decoding by a variable-length decoder whenever an additional increment is made available from said incremental redundancy decoder for said variable-length decoder for that k-bit message;
• (g) wherein said incremental redundancy decoder is configured for utilizing increments corresponding to each successfully-decoded k-bit message to subsequently produce additional increments for said variable-length decoders until no more new increments from successfully-decoded k-bit messages are available;
• (h) wherein said number of received symbols received by the incremental redundancy decoder is less than L×(m−1)×Δ, corresponding to the common pool of incremental redundancy, which approximates said number of symbols of incremental redundancy that would have been sent by L independently operating variable-length encoders if said increments were received based on non-active ACK/NACK feedback from a receiver on that same channel;
• (i) wherein a communications system utilizing said receiver apparatus approaches Shannon capacity of said specified point-to-point channel, having a rate similar to that achieved by capacity-approaching variable-length code when used with non-active ACK/NACK feedback;
• (j) wherein probability of either failing to decode a k-bit message, or decoding a k-bit message in error, is below a target value;
• and
• (k) wherein k is a number of bits in a message that is encoded by a variable length encoder, is a length in symbols of a transmission, m is a number of stages including an initial transmission and m−1 additional stages of incremental redundancy, and L is a number of short-blocklength codewords.