Research On Limits Of Statistical Parameters For Radio Interference

The radiation limits provided by International Special Committee on Radio Interference (CISPR) aim to protect analog radio systems, the key parameters of which are quasi-peak (QP) limits for interference sources. However, the key parameter for reliability of digital communication systems is the bit error rate (BER) of sending signal, so the method based on output of the quasi-peak (QP) detector is no longer the best choice to estimate the impact on digital communication systems from interference, a new detection method and radiation limits need to be defined. Amplitude probability distribution (APD) detection technology has been formally brought into the CISPR16-1-1.End.2in2006, but the relevant limits are still under discussion. According to the research and accomplishment on APD technology, a theoretical method for evaluating the BER of digital communication systems, especially the spread spectrum communication systems by using the APD measuring results of interference is proposed in this thesis, In order to provide feasible basis for establishing the APD limits, the feasible scheme of ensuring the limits of APD for different kinds of modulation systems is presented based on the theoretical method.Firstly, the dissertation analyzes the theoretical basis of statistical measurement method, which includes following several parts:(1) The APD characteristics of typical distribution signals are introduced.(2) The thesis builds the simulation model of APD measuring system, the characteristic of APD in different measuring bandwidths is simulated and analyzed, and a method of converting the APD to different measuring bandwidths is presented.(3) The measurement results of APD for different interferences and the BER of PHS system which is impacted by the corresponding interferences are compared. According to the similarity of the two, the conclusion that the APD of interference can be used to evaluate the performance of digital communication systems is proved in this thesis.Secondly, because the phase of interference has not been considered in traditional derivation for the BER of digital communication systems, a new assessment algorithm is presented in this dissertation. Based on the constellation of digital signals, taking into account the phase and amplitude of interference, the assessment algorithm can evaluate the BER of digital communication systems using APD. Supposed that the phase distribution of interference is uniformed, the BEP from theory is achieved by numerical analysis and calculation. The theoretical calculation accords well with simulation result, which shows that the assessment algorithm and the analytical method using constellation are applicable. Particularly, the dissertation applies the algorithm to analyze the BER of direct sequence spread spectrum systems (DSSS) and frequency hopping spread spectrum systems (FHSS), and the assessment algorithm of evaluating the BER of DSSS and FHSS is presented. At the same time, the BER of baseband systems and spread spectrum communication systems are simulated, and the BER of Bluetooth communication system is measured. Through a lot of simulation and practical measurement, the conclusion getting from theoretical analysis in this thesis is verified. Based on all of these, the concept of channel correction factor is proposed, which aims to improve the shortage of the theoretical model for ignoring the channel model.Finally, the feasible scheme of ensuring the limits of APD that meets the BER requirements of baseband modulation systems, spread spectrum systems and error correction coding systems is proposed.The dissertation consists of5chapters, including53figures,6tables, and33references.