PN code FFT parallel acquisition method based on majority decision

Abstract

The invention discloses a PN code FFT parallel acquisition method in wireless communication techniques. The method includes the steps of generation of a short pseudo code set of a transmitting end, generation of a base band modulating signal, up-conversion processing and signal transmission, generation of a short pseudo code set of a receiving end, signal receiving and down-conversion processing, frequency domain matching and correlation solving, and majority decision. According to the method, a long pseudo code is converted into G short pseudo codes, all the short pseudo codes are connected in a cascading mode to generate the short pseudo code sets, the short pseudo code sets in the same cascading mode are adopted in a receiver at the same time so as to carry out frequency domain matching coherent processing, and then majority decision based on chip delay is carried out; in this way, the method has the advantages that the sensitivity to channel noise is low, accurate channel estimation is not needed during acquisition, acquisition accuracy is high, and the robustness of decision criteria is improved as well due to the adoption of majority decision. A required signal-to-noise ratio in a Rayleigh channel is -13dB or so when the acquisition probability of the method is 95%, and the gain of the signal-to-noise ratio is improved by 12dB or so when compared with the required signal-to-noise ratio of -1dB in background technologies.

Description

Technical field [0001] The invention belongs to the field of wireless communication technology, and specifically relates to a PN code FFT (Fast Fourier Transform) parallel acquisition decision method based on large number decision in a direct sequence spread spectrum (DSSS) communication system. Background technique [0002] In a spread spectrum communication system, in order to perform despreading correctly, pseudo code synchronization must be performed, that is, a pseudo code synchronized with the sender is generated at the receiving end and changes with the pseudo code of the sending end (that is, the phase and rate are the same) . Pseudo-code synchronization is the key to a spread spectrum system. It is divided into two stages: acquisition (coarse synchronization) and tracking (fine synchronization). Among them, acquisition is the most difficult problem to solve in the synchronization problem. Its performance directly determines the reliability and effectiveness of the sprea...

AI Technical Summary

Problems solved by technology

[0019] 1. Synchronous acquisition judgment is highly sensitive to channel noise. In engineering applications, with the real-time change of channel noise, it is easy to cause wrong judgment of synchronous acquisition;

[0020] 2. Synchronous capture decision criterion is too simple: the criterion for successful synchronous capture is only related to the threshold value V T A single comparison is performed once the threshold V T There is a large error in the calculation, that is, it is easy to cause wrong judgment of synchronous capture

Images