Research On Perfect Discrete Signal And Its Applications

Time-discrete signal with good autocorrelation properties are used in various application in measurement, digital communications and continuous– wave (CW) radar, where the desired information is extracted from the received signal using the periodic autocorrelation in recent several decades. Discrete signal with good correlation properties is an important problem paid eagerly attention and researched deeply in the field of information theory. Several sequence pairs and mismatched filtering signals are researched in this paper.First, a new periodic correlation discrete signal is proposed, which can be called as perfect almost-quadriphase sequence pairs. The transformation properties and existing condition of the perfect almost-quadriphase sequence pairs are presented. A kind of constructing method of perfect quadriphase sequence pair with only one nonuniform element is given, and the length of the signals can be extended. From the result above two, we can design more length perfect quadriphase signals. A constructing method of ternary sequence pairs by using correction identity is presented.Two new methods for constructing sets of zero-correlation zone (ZCZ) sequence pair are proposed. Almost optimal or optimal ZCZ sequence pairs set can be generated from the correlation product of special unitary matrices and difference shifted sequence of perfect sequence pair.Based on known ZCZ sequence pair set, two new methods of constructing ZCZ sequence pairs set with wide zero correlation zone and four kinds of methods of constructing ZCZ sequence pairs with both large family size and wide zero correlation zone are proposed. They can be generated from the correlation product of special unitary matrices and the difference shifted form of original ZCZ sequence pairs set. The researching result enriches the theory of ZCZ sequence pairs set.Periodic and odd-periodic quadriphase mismatched filtering arrays are proposed. Exiting conditions and construction methods of folding and periodic multiplication for periodic and odd-periodic quadriphase arrays are presented. All sidelobe of above periodic or odd-periodic correlation arrays converges to zero so their influences vanished with quadriphase array size is enlarged.The influence of CW interference in direct sequence spread system (DSSS) based on sequence pair is derived, and simulation verification is given later. The ZCZ sequence pair designed above was applied to quasi-synchronous code division multiple access (QS-CDMA) system, simulation results show that they can satisfy the demand of the real system.A new approach which using mismatched filtering sequence and sequence pair to channel estimation in orthogonal frequency division multiplexing (OFDM) systems is proposed. Theoretical analysis and simulation results show that the new method has good property of low complexity, accurate estimation and better BER performance.