A kind of demodulation method of tcm-cpm signal in multipath channel

Abstract

The present invention provides a method for demodulating a TCM-CPM signal in a multipath channel. The implementation steps are as follows: a TCM-CPM modulator modulates a binary sequence, a frequency offset estimator performs frequency offset compensation on the modulated signal, and a demodulator performs frequency offset compensation on the modulated signal. The first Viterbi demodulation is performed on the frequency offset compensation signal, and then the demodulator performs the second Viterbi demodulation on the frequency offset compensation signal. The present invention uses the demodulated symbol, the current demodulated symbol and the modulated signal corresponding to the first demodulation result as the reference signal and the channel gain value during the second Viterbi demodulation calculation branch metric process. It can suppress the influence of multipath interference on the demodulation result to the greatest extent, and effectively reduce the bit error rate.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, and further relates to a method for demodulating a TCM-CPM signal in a multipath channel, which can be used for demodulating a TCM-CPM signal in a multipath environment. Background technique [0002] TCM-CPM modulation has received close attention due to its excellent power and bandwidth efficiency. By introducing inherent inter-symbol interference (ISI) into the signal, the spectral shape of the TCM-CPM signal can be easily adjusted to meet system requirements. [0003] Continuous phase modulation CPM originated in the late 1970s and is less affected by nonlinear distortion due to its constant envelope characteristics. Coupled with its compact spectrum, less high-frequency components, and large sidelobe suppression, it has a good development prospect. But in today's complex wireless communication environment, pure CPM modulation technology cannot achieve better bit error perform...

AI Technical Summary

Problems solved by technology

In order to eliminate multipath interference and reduce the bit error rate, an equalizer can be added in front of the demodulator to eliminate multipath interference, but this will inevitably lead to a complex structure at the receiving end and increase the design difficulty of the receiving end

[0006] In Zhang Rongbo's master thesis TCM-CPM modulation and demodulation technology research published in 2017, a low-complexity coherent and non-coherent TCM-CPM signal demodulation method is disclosed. In coherent demodulation, this method The phase distance path exclusion algorithm is used to reduce the amount of correlation calculation at the receiving end. In the non-coherent demodulation, the simplified state non-coherent sequence detection algorithm based on decision feedback can be used to reduce the number of decoding states through reasonable state merging. Under the condition of small performance loss, the complexity of the receiver is reduced, but it is under the premise of Gaussian additive white noise channel. When the channel condition is a multipath channel, the problem of multipath interference cannot be solved, which will lead to errors higher code rate

Images