Pseudo-code sequence blind estimation of synchronous DS-CDMA (Direct Sequence-Code Division Multiple Access) signal containing residual frequency offsets

Abstract

The invention claims to protect a pseudo-code sequence blind estimation method of a synchronous DS-CDMA (Direct Sequence-Code Division Multiple Access) signal containing residual frequency offsets based on the combination of eigen decomposition and a DPLL (Digital Phase Lock Loop), and belongs to the technical field of signal processing. The pseudo-code sequence blind estimation method comprises the following steps: on the premise of knowing a pseudo-code sequence period and a chip width, segmenting a received signal according to a single-fold pseudo-code period in order to construct a signal covariance matrix and performing eigenvalue decomposition; estimating the user number of the DS-CDMA signal according to an MDL (Minimum Description Length) principle in order to further extract a feature vector corresponding to a maximum eigenvalue which is equal to the user number, and realize rough extraction of each user pseudo-code sequence; lastly, inputting the pseudo-code sequence undergoing the rough estimation into the DPLL to eliminate the residual frequency offsets, wherein an I-path signal output by the DPLL is taken as a pseudo-code sequence undergoing final blind estimation. By adopting the method, aliasing residual frequency offsets in the pseudo-code sequence are eliminated through the DPLL, and the estimation problem of the pseudo-code sequence of the DS-CDMA signal containing the residual frequency offsets under a low signal-to-noise ratio is solved effectively; moreover, an algorithm is easy to operate and is not limited by a spreading code type, and the method has important engineering practical significance.

Description

technical field [0001] The invention relates to blind processing of direct sequence spread spectrum signals in the field of communication, in particular to a method for blindly estimating pseudocode sequences of synchronous DS-CDMA signals with residual frequency offset under low signal-to-noise ratio. Background technique [0002] The Direct Sequence-Code Division Multiple Access (DS-CDMA) system is one of the Direct Sequence Spread Spectrum (DSSS) communication systems. The DS-CDMA signal uses multiple pseudo-random codes Modulating the information code to broaden the spectrum, compared with conventional narrowband communication signals, has the advantages of good concealment, anti-interference, low probability of interception, and strong confidentiality, and is widely used in military and civilian communications. Such as: communication, radar, GPS global satellite timing positioning system, remote sensing and remote control and other fields. However, in non-cooperative s...

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Problems solved by technology

[0005] The technical problem to be solved by the present invention is to propose a Pseudo-code sequence containing residual frequency offset combined with eigendecomposition and DPLL for the current problem that it is difficult to estimate the pseudo code sequence of the synchronous DS-CDMA signal containing residual frequency offset in the case of low signal-to-noise ratio. A Blind Estimation Method of Pseudocode Sequences for Synchronous DS-CDMA Signals

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