Study On Joint Detection Algorithm Based On Channel Estimation In TD-SCDMA System

TD-SCDMA, which combines all the advantage of the TDD and CDMA, isone of the three main standards of third-generation mobile radio system.TD-SCDMA is an interfere-limiter system. Here includes multi-pathinterference, multi-user interference of intra-cell and inter-cell interference.Those destroy the orthogonality of each channel which reduces the utility offrequence-spectrum in TD-SCDMA system. As a key technique of TD-SCDMA,Joint Detection takes all interferer users as useful signals which can makefulluse of the spread code, range, timing and delay of all users. In this paper wework over the Joint Detection technology in TD-SCDMA which is based onarray antenna. The main works of this paper can be summarized as follows:1. The detailed mathematics inference of the Joint Detection algorithm isgiven, and the key of Joint Detection algorithm—system matrix is introduced.Analyze three kinds of linear joint detection algorithm, describe their principleand compare the performance of them. At last, give the system matrix respectively.2. Investigated the channel estimation algorithm in TD-SCDMA system,especially elaborated the channel estimation which based on training sequence.The construct of training sequence in TD-SCDMA is described and thesimulation model of channel estimation is given. Simultaneously theperformance of channel estimate algorithm which uses training sequence issimulated with joint detection algorithm. The results shown that: theconclusions of channel estimation algorithm which based on training sequenceis very close to the reality value, and achieves the communication standard.3. Due to high computational complexity of Joint Detection algorithm, weintroduce block Fourier algorithm and explain its principle and the applicationin TD-SCDMA system in detail. Select ZF-BLE as the simulate algorithm,simulate Joint Detection algorithm performance in different occasions, such asvarying antenna number, user number and traveling speed. Combining theoryanalyses and simulation results, we draw some conclusions: without reducingthe performance of TD-SCDMA system, the improver algorithm has higheroperation efficiency, the order of magnitude less than O(n~2), and the storagedescends with times than tradition algorithm.