Research For The 3G's Multi-rate Transmission And Its Improved Multi-rate Scheme

Multi-rate transmission technology is an essential technology for multimedia services in the 3G mobile communication system. The research in this paper is put the emphases on the two 3G's multi-rate schemes-OVSF multi-rate scheme and Multi-code multi-rate scheme at first. Then based on the research, an improved multi-rate scheme is proposed. The main research and results are the following:(1) The properties and problems of the OVSF multi-rate transmission The properties and the model of the OVSF system are introduced, the generation and allocation of OVSF code are analyzed, and the code blocking problem and the Near-Far problem in OVSF system are discussed in detail.(2)The properties and problems of the multi-code multi-rate transmission The system model is presented, the factor of the system's velocity resolution and the allocation of parallel branch codes are discussed, and the problem caused by multi-code system's signal instantaneous magnitude is analyzed.(3) An improved multi-rate scheme In order to take use of the advantages and overcome the disadvantages of OVSF system and multi-code system, an improved multi-rate scheme is proposed in this paper. The improved system models are built, and the key module;-velocity transfer algorithm is analyzed in detail, the general performances of the three multi-rate schemes are compared finally.(4) The BERs of the three multi-rate schemes in AWGN channel The BER model of multi-rate system in AWGN channel is built, and the BERs of the three multi-rate schemes are analyzed and compared, a conclusion that the BERs of the three multi-rate schemes are identical is obtained.