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Pi/2 phase shift non-square M-QAM modulation and demodulation method and its system

A modulation and demodulation, M-QAM technology, applied in the field of digital information transmission, can solve the problems of different, unsatisfactory equalization effect, difficult to realize, etc.

Inactive Publication Date: 2005-08-03
TSINGHUA UNIV
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Problems solved by technology

[0005] Since QAM modulation uses both the amplitude and phase of the signal to convey information, it is more susceptible to channel nonlinearity
The AM-AM response and AM-PM response of the nonlinear channel will distort the constellation diagram of the QAM signal and seriously affect its transmission performance
In a system using QAM modulation, a common way to combat channel nonlinearity is to use the above-mentioned pre-distortion or channel nonlinear equalization. As mentioned above, pre-distortion technology not only needs to have a clear understanding of the nonlinear characteristics of the channel Understand, but also at the cost of power; nonlinear equalization generally has high complexity and is not easy to implement; and it is different from the equalization of multipath signals, and the equalization effect is not very ideal

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  • Pi/2 phase shift non-square M-QAM modulation and demodulation method and its system
  • Pi/2 phase shift non-square M-QAM modulation and demodulation method and its system
  • Pi/2 phase shift non-square M-QAM modulation and demodulation method and its system

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Embodiment Construction

[0041] Due to the general non-linear characteristics of the channel, the constellation diagram of the data modulated by the QAM modulation method will be distorted during the channel transmission, thereby affecting the transmission performance. The present invention proposes a method of transmitting two constellation diagrams with a difference of π / 2 at odd and even moments, which eliminates the 180-degree phase jump in signal transmission and reduces the fluctuation of the envelope, so it is better than the commonly used QAM modulation method It can better resist the nonlinearity of the channel.

[0042] First, at the sending end, use the frequency-divided clock as the odd-even time control signal to control the phase of the carrier signal, keep the phase constant at the odd time, and shift the carrier phase by π / 2 at the even time, and then use the controlled carrier to The baseband data is modulated, so that the constellation diagrams of the modulated data at odd and even m...

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Abstract

The modulation / demodulation method of non-square M-QAM of pi / 2 phase shift characterizes in transmitting two signal constellation patterns different in pi / 2 at odd-even time, which can effectively eliminate 180deg phase jump in the modulation of non-square M-QAM so as to reduce the envelope fluctuation of the signals.

Description

technical field [0001] The invention belongs to the technical field of digital information transmission, in particular to a π / 2 phase-shifted non-square M-QAM modulation and demodulation technology. Background technique [0002] Commonly used digital modulation and demodulation techniques include amplitude shift keying (ASK), frequency shift keying (FSK) and phase shift keying (PSK) as well as quadrature amplitude phase (QAM) modulation and demodulation techniques, as well as their variation and extension. Some modulation and demodulation techniques. Among them, compared with other digital modulation methods, the QAM modulation method can achieve better transmission performance under the same spectrum utilization rate, so more and more people pay attention to it, and it is also widely used in various digital communications. system. Square QAM modulations such as 16QAM, 64QAM and 256QAM are more commonly used, but non-square QAM modulation methods such as 8QAM, 32QAM and 12...

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Application Information

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IPC IPC(8): H04L27/34
Inventor 杨知行刘昌清郭兴波潘长勇王军
Owner TSINGHUA UNIV
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