Identification method of digitally modulated signal with frequency offset and phase offset in multipath fading channel
A digital modulated signal and multipath fading channel technology, applied in the field of communication, can solve the problems of unsatisfactory recognition effect and poor recognition performance, and achieve the effect of improving recognition performance and good recognition performance
Inactive Publication Date: 2016-03-23
XIDIAN UNIV
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Problems solved by technology
WilliamC.Headly et al. proposed an asynchronous modulation identification method for amplitude-phase modulation signals in flat fading channels, but the identification performance of this method is poor in the case of low signal-to-noise ratio
To sum up, these studies are all carried out under Rayleigh fading or flat fading channel conditions, but they are not suitable for frequency-selective multipath fading channels in actual non-cooperative communication systems, and the identification effect is not ideal in the case of low SNR
Therefore, the above methods are not suitable for application in actual non-cooperative communication systems
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[0021] The present invention will be described in detail below in conjunction with specific embodiments.
[0022] Please refer to Figure 1 to Figure 6 , the specific implementation steps of the present invention are as follows:
[0023] Step 1, sample the received signal y(t) to obtain y[n];
[0024] Step 2, calculate the cyclic spectrum of y[n]
[0025] Assuming that the baseband receives the signal y(t), there is a phase deviation θ 0 , frequency offset f c , the influence of additive white Gaussian noise n(t) and the multipath fading channel with path number P, expressed as:
[0026]
[0027] In the formula and t l respectively l The channel response and receiving delay on the path, x(t) corresponds to different modulation signals. make
[0028]
[0029] Normally the signal y 1 (t) and noise ω(t) are uncorrelated, and the cyclic spectrum of the received signal y can be obtained from the cyclic spectrum properties of the uncorrelated added signal for: ...
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The invention relates to a method for identifying a digital modulation signal containing frequency deviation and phase deviation under a multipath fading channel, which comprises the steps of (1) sampling a received MPSK (Multi-Phase Shift Keying) signal y(t) to obtain y(n); (2) calculating a cyclic spectrum shown in the abstract; (3) calculating an amplitude (shown in the abstract) of a spectrum coherent equation of a digital modulating signal; (4) searching the maximum value of the amplitude on a frequency shaft f, and taking the maximum value as an identified characteristic value; (5) setting a judgment threshold of a signal set to be as the formula shown in the abstract, wherein delta i is a threshold values of adjacent signals or signals Y1 and Y2, max (rY1) is the maximum value of the mean value of characteristic values of the signal Y1, and max (rY2) is the minimum value of the mean value of the characteristic values of the signal Y2; and (6) identifying BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying ) and 8PSK (8-Phase Shift Keying) signals containing frequency deviation and phase deviation according to the set judgment threshold.
Description
【Technical field】 [0001] The invention belongs to the technical field of communication, and in particular relates to a method for identifying a digital modulation signal containing frequency offset and phase offset in a multipath fading channel, which can be used to identify the modulation mode type of the digital modulation signal in a non-cooperative communication system. 【Background technique】 [0002] Non-cooperative communication is a communication mode that accesses the cooperative communication system without affecting the normal communication between the cooperative communication parties. It is an unauthorized access communication mode. It has a wide range of applications in spectrum management in civilian communications, communication fault detection, and communication countermeasures in military communications. In an actual non-cooperative communication system, after the receiver estimates the carrier frequency, it needs to down-convert the signal. It is possible ...
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IPC IPC(8): H04L25/02H04L27/20H04B1/711
Inventor 李兵兵刘明骞曹超凤孙珺
Owner XIDIAN UNIV