A physical layer synchronization method and system of a narrowband communication system

Abstract

The invention discloses a narrowband communication system physical layer synchronization method and system, and the method comprises the steps: firstly dividing a physical frame into an automatic power control part, a first synchronization code part, and an information sequence part, wherein the first synchronization code part is disposed between the automatic power control part and the information sequence part; then, introducing a linear frequency modulation signal sequence into the first synchronous code part; and finally, adding a PN sequence into the information sequence part. The linearfrequency modulation signal sequence is used as a synchronous code and is not influenced by individual bit error codes caused by interference and noise, and due to the fact that the PN code is introduced, after the linear frequency modulation signal sequence is processed, even if a synchronous error of one or more symbols exists, correction can be conducted through the PN code.

Description

technical field [0001] The invention belongs to the field of railway communication, in particular to a physical layer synchronization method and system of a narrowband communication system. Background technique [0002] In various communication systems, the purpose of frame synchronization is to find the start and end time of each frame or to give the beginning and end time of each frame. When a communication system receives a frame, it is only captured after a successful synchronization, and the information it carries is then decoded. Therefore, before the frame is sent, it is necessary to insert a synchronization code into the frame. In the existing synchronization technology, the insertion position of the synchronization code can not only be inserted at the frame header and at the same time at the frame header and frame tail, but also can be inserted in a known position in the information code. The positions are scattered for insertion. In a system with a fixed frame le...

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Problems solved by technology

[0004] However, in practical applications, there are bit errors caused by various noises, interference, and Doppler frequency shifts in the existing synchronization code implementation methods, which cause errors in individual bits in the synchronization code, resulting in missed recognition at the receiving end of the communication system. Or misrecognition, if the information code contains the same symbol as the synchronization code, false synchronization may also occur in the communication system, among which missing recognition, misrecognition and false synchronization will cause decoding failure

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