Research Of TD-SCDMA Physical Layer And Key Technique

TD-SCDMA was proposed in 1998 on behalf of China by CATT (Chinese Academy of Telecommunication Technology), and approved by ITU (International Telecommunications Union) as one of the international CDMA standards for 3G mobile communications in May 2000. TD-SCDMA adopts a series of techniques, such as TDD, synchronous CDMA, smart antenna, joint detection, software radio, baton handover, dynamical channel allocation, and so on. Its expected advantages are unpaired frequency band, flexible frame structure, suitable for asymmetrical service, higher expected theoretical spectral efficiency, low expected cost of infrastructure by using smart antenna and TDD technology, etc.The paper firstly introduces these international CDMA standards for 3G mobile communications, including WCDMA, CDMA2000, TD-SCDMA and WiMAX approved by ITU in Oct 2007.Then the architecture of TD-SCDMA physical layer is simply described. According to the specifications of 3GPP LCR TDD physical layer, the system framework of TD-SCDMA physical layer simulation platform is issued, and the paper concretely describes the part of transportation channels coding and multiplexing, including the modules of channel coding, transportation multiplexing, convolution codes & Turbo codes, interleaving, rate matching and etc. Lastly, the results of simulation experiment of TD-SCDMA transportation channels disposal is given and analyzed.This paper finally introduces HSDPA theory and key techniques, and then analyzes application of HSDPA technique in TD-SCDMA system. HSDPA is a combination of several key techniques which all contribute to the enhanced capabilities of the downlink channel. 3GPP R5 HSDPA includes HARQ (hybrid automatic request), AMC (adaptive modulation and coding) and NodeB fast scheduling functionality. It relies on a new type of transport channel, the HS-DSCH, which is terminated in the Node B and controlled by MAC-hs. Based on N frequency Cell technique, TD-SCDMA multi-carrier HSDPA, by multi-carrier binding and little alteration, can efficiently improve the peak speed and cell data throughput.