Research On The HARQ System And Its Encoding And Decoding Technology

Hybrid automatic repeat request (HARQ) technique is the main support technique for the high speed data transmission in 3GPP standard. The paper focus on the HARQ technique of the HSDPA system. The conventional HARQ system could be divided into three types: type-â… , type-â…¡and type-â…¢HARQ system. Based on the analysis of conventional type-â… HARQ system, the new type-â… and type-â…¡sub-packet HARQ systems are given. Based on the conventional type-â…¡and type-â…¢HARQ system, the new HARQ systems based on RCPC, RCPT and LDPC code are given. The structure of the new HARQ system is generated. The advantages of the new HARQ system are proved by the theoretical analysis and simulations. The details of the innovations of the paper are as follows.(1)Two novel sub-packet hybrid ARQ (SPHARQ) systems are proposed by combining the sub-packet transmission system with type-â… HARQ system. A method with the fixed retransmission times is investigated for type-â… SPHARQ system to decrease the transmission delays. Based on type-â… S PHARQ system, type-â…¡SPHARQ system is constructed. Two methods of adding tail bits to each sub-packet and doing combination before being despread to increase the performance of type-â…¡SPHARQ are investigated.(2)Based on the type-â…¡a nd type-â…¢HARQ system and RCPC code, a new HARQ system is proposed in which F sub-packets could be transmitted in one data packet, at receiver the same F sub-packets are combined with each other to form a reliable packet equal to the punctured combined sequence after F retransmission. The optimal number of repeat sub-packets is obtained to improve the performance of new HARQ system. The new HARQ system has the advantages of type-â…¡a nd type-â…¢HARQ system.(3)Based on the type-â…¡a nd type-â…¢HARQ system and RCPT code, a new HARQ system is proposed by combining the sub-packet transmission scheme with the averaged diversity combining technique. In the new HARQ system the diversity combining of a data packet and its copies in the retransmissions is converted to the diversity combining of the identical sub-packets in one data packet. A new interleaver is designed for the new HARQ system which helps to the combination of parity sub-packets of RSC2 of Turbo code. In addition the delay for interleaving of Turbo code in new HARQ system is decreased greatly. The minimum distance of Turbo code...