A Differential Polar Modulation Method to Eliminate CPE in OFDM System

Abstract

The invention discloses a differential polarization modulation method for eliminating CPE (common phase error) of an OFDM (orthogonal frequency division multiplexing) system, and belongs to the technical field of wireless communication. The polarization domain of signals is utilized, and the scheme of simultaneously transmitting polarization signals at the same frequency and carrying out reverse phase differential demodulation DPOLSK (differential polarization shift keying) at the receiving end for eliminating the CPE is adopted. Polarization signals are generated at the emitting end through polarization modulation, the phase difference of the two components of the signals is used for carrying emitting information, the two components of the polarization signals are influenced by the CPE at the receiving end, the constellation rotation angles are identical, the constellation rotation direction of one path of component can be opposite through the phase reversing, then, the constellation rotation can be counteracted through differential multiplication, the goal of eliminating the CPE is reached, and meanwhile, the emitting information is demodulated out. The differential polarization modulation has the advantages that the apriori information of the phase noise does not need to be obtained, a complicated prediction algorithm is not used, the real-time performance is high, the method is used for eliminating the influence of the CPUE on the OFDM receiving signals, and the BER (bit rate ratio) of the system is reduced.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, in particular to polar modulation technology and phase noise in OFDM system. Specifically, it refers to a differential polarization modulation method for eliminating CPE in an OFDM system. Background technique [0002] With the advent of the era of wireless broadband networks, Orthogonal frequency division multiplexing (OFDM) technology has been widely used as an efficient multi-carrier technology. symbol interference (ISI) has better suppression performance, and has better robustness to the multipath effect caused by multi-carrier. However, in the OFDM system, the output of the local oscillator is not ideal due to noise and disturbance, and phase noise (Phase Noise, PHN) will be generated, which will cause the common phase error (Common Phase Error, CPE) of the subcarrier constellation of the received signal in the OFDM system, resulting in erroneous Bit rate (Bit Error Ratio, B...

AI Technical Summary

Problems solved by technology

These methods of suppressing CPE have their own deficiencies. For example, the LO hardware design requires more financial support, which will make the equipment more expensive; The additional overhead is to extract and process the information carried in the pilot frequency, which has a large delay and is not practical in high-speed communication; the decision-oriented compensation method depends on the correlation between symbols and is sensitive to decision errors, such as When the change is large, it will cause a large error and high complexity; the frequency spectrum of the self-cancellation method is only half of that of the OFDM system using traditional modulation, and there is a problem of extremely low spectral efficiency

Therefore, the PHN suppression and elimination technology in the existing OFDM system generally has the problems of high consumption and high complexity, and has obvious defects in practical applications, and is not universally applicable.

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