Automatic retransmission query (arq) with inner code for generating

Abstract

The invention discloses techniques for providing automatic retransmission query (ARQ) functions in a communication system. A transmitter in the system applies an input data packet to a first convolutional encoder operating at a first rate to generate an inner code including multiple encoded packets. The encoded packets are interleaved and applied to a second convolutional encoder operating at a second rate which generates an outer code including a transmit packet generated from each of the encoded packets. A first transmit packet is sent to a receiver, which decodes the transmit packet in a Viterbi decoder operating at the second rate to generate a decoded version of the first transmit packet. The decoded version is inverted to provide a first provisional decoding of the input packet. If a cyclic redundancy code (CRC) check of the first provisional decoding is passed, the receiver sends an ACK signal to the transmitter and no retransmission is required. If the check is not passed, the transmitter sends one or more additional transmit packets, which are processed in a manner similar to the first transmit packet to generate one or more additional provisional decodings of the input data packet. If a CRC check of a given one of these additional provisional decodings is passed, the receiver accepts it as the input packet and sends an ACK signal to the transmitter. If none pass the CRC check, the receiver may combine decoded versions of the transmit packets, and apply the result to a Viterbi decoder operating at the first rate to generate another provisional decoding of the input packet. This provisional decoding is accepted as the input packet if it passes a CRC check.