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The Application of Time-Domain Phase-Inversion Symmetric Method in CDMA
Author: HanXiaoFeng
Tutor: XiaoBaoZuo
School: Taiyuan University of Technology
Course: Communication and Information System
Keywords: Inverse symmetry method CDMA Noise Correlation
CLC: TN929.533
Type: Master's thesis
Year: 2011
Downloads: 18
Quote: 1
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Abstract
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CDMA is a direct sequence spread spectrum technology (Direct Sequence Spread Spectrum DSSS). DSSS abbreviated for the DS, it is obtained by increasing the bandwidth to the strong anti-interference ability. But correlation, spreading gain not achieve the desired results due to the adjacent timeslot noise between. In order to make full use of the limited spectrum resources for a stronger anti-interference ability, using a variety of techniques. Of the adverse effects of such orthogonal codes and quasi-orthogonal codes, chaotic sequence spread spectrum, but they can not overcome the noise. Inverting symmetric Act (Phase-Inversion Symmetric Method, PISM), my mentor proposed the use of noise to suppress noise, unfavorable factors into favorable factors, significantly improves the signal-to-noise ratio, and get a Chinese invention patents. Paper mainly on the time domain PISM PISM with DS has been improved without increasing the bandwidth conditions, allowing the system SNR. The main work is as follows: (1) on the band-limited noise correlation analysis. Using MATLAB software on the adjacent slot noise simulation results show that the adjacent slot noise correlation, and the time slot, the stronger the smaller the correlation. Oscilloscope to test the the adjacent timeslot artificial noise and natural noise correlation data, the results show that the adjacent slot man-made noise is greater than the natural noise. After repeated tests showed that both natural noise or man-made noise in the adjacent slot are positively correlated, the correlation coefficient p gt; 0. (2) describes the basic principles of PISM theoretical analysis and system simulation of the time domain PISM noise immunity. Analysis PISM principle to obtain the PISM SNR gain formula for GPISM, = 2 / (1-ρ). Analysis of the relationship of PISM Shannon theorem. Range of obtained PISM applicable. The anti-noise performance compared PISM existing diversity techniques. Through feasibility of time domain PISM of theoretical analysis, get the band-limited noise conditions, The SNR gain time domain PISM system GPISM ≈ 3.1. The anti-noise performance under PISM different chip rate simulation experiment using MATLAB software. (3) combine PISM and DS structures PISM-DS system model, test the model of Gaussian white noise, narrowband interference, comb interference, anti-interference ability of broadband interference. Using Multisim software codec circuit design PISM. The experimental results show that, in the same bandwidth, the same messaging rate and the same signal-to-noise ratio conditions, PISM-DS system is stronger than the DS system's anti-interference ability.
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CLC: > Industrial Technology > Radio electronics, telecommunications technology > Wireless communications > Mobile Communications > Cellular mobile communications systems (mobile phones, mobile phone handsets ) > Code Division Multiple Access (CDMA) mobile communication
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