Carrier recovery method in high order modulation-demodulation

A technology of carrier recovery and high-order modulation, which is applied in the direction of phase-modulated carrier system and multi-carrier system, etc. It can solve the problems that the carrier capture range is less than ±10kHz, the polarity algorithm is complicated, and the implementation is difficult.

Active Publication Date: 2013-10-23
山东泉清通信有限责任公司
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Problems solved by technology

The methods used mainly include: Maximum Likelihood Parameter Estimation (ML) error estimation algorithm, which has a complicated process of finding the likelihood function and is very difficult to implement; Decision-oriented (DD) algorithm, which is simple to implement, but the carrier capture range is less than ± 10kHz, which cannot meet the needs of users; RC algorithm, which is not suitable for 128QAM systems without outer corners; polarity judgment phase detection algorithm is currently the most used algorithm, but when the frequency deviation is very large, the polarity algorithm become very complicated

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[0048] figure 1 It is a schematic diagram of the hardware platform structure required when the present invention is implemented, and the hardware platform is mainly composed of a service interface part, a monitoring unit, an FPGA circuit, a D / A converter, a quadrature modulation circuit, a quadrature demodulation circuit, a local oscillator circuit, an A / D converter composition. After the business information enters the FPGA, after sampling, demultiplexing into frames, multi-level coding mapping, insertion of auxiliary training sequences, shaping filtering, and D / A conversion, it is orthogonally modulated into an intermediate frequency signal; the receiving end will receive the modulated intermediate frequency signal After quadrature demodulation, it becomes two-way quadrature signals of I and Q, and after being filtered by a low-pass filter, it is differentially amplified and sent to the A / D converter. The I and Q 10-bit signals output by the A / D are sent to the FPGA unit. ...

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Abstract

The invention relates to the field of microwave communication, in particular to a carrier recovery method in high order modulation-demodulation. According to the method, carrier recovery is performed by inserting an auxiliary sequence and utilizing the correlation of the auxiliary sequence, and the method comprises the steps of extracting clocks, generating timing frames, recovering and compensating the frequency difference of received carriers and transmitted carriers, recovering and compensating the phase difference of the received carriers and the transmitted carriers, removing phase ambiguity, and the like. According to the method, the auxiliary sequence is utilized repeatedly to carry out correlation operation, computation of the frequency difference and the phase difference, and correlative compensation, so that the anti-interference ability is good, carrier phases can be reliably recovered under the condition of low signal to noise ratio for completing signal demodulation, and the robustness is high, and in addition, a symbol rate is adopted in a realization process, requirements on a dependent hardware platform are lower, and coding is simple to realize.

Description

technical field [0001] The invention relates to the field of microwave communication, in particular to a carrier recovery method in high-order modulation and demodulation. Background technique [0002] With the development of current communication technology, the frequency resources are getting tighter and tighter, and the capacity of traditional communication systems can no longer meet the requirements of users. High-order modulation and demodulation has attracted more and more attention. High-order modulation and demodulation can not only improve the transmission capacity of the system, but also greatly improve the spectrum utilization rate. The development of digital signal processing devices and people's interest in broadband wireless applications have promoted the rapid growth of high-order modulation and demodulation technology. With the high development of microelectronics technology, through the breakthrough and innovation of three key technologies (software and har...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/38H04L27/22
Inventor 赵宪臣王国利曹桂芹蔡学福赵廷玺王传超
Owner 山东泉清通信有限责任公司
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