A method and system for elimination of the multi-path interference and carry frequency deviation

Abstract

This invention discloses one method to delete multi-radium interference load wave bias frequency, which comprises the following steps: a, even device adopts blind even formula method to remove input signal of its interference data for collecting signals; b, after getting even part to capture formula load wave phase bias by use of blind formula; c, after capturing load wave phase bias, using character estimation aid formula to locking load wave phase bias; d, after locking, even part adopts characters to judge aid LMS formula to delete input signal multi-radium interference.

Description

technical field [0001] The invention relates to the field of communication technology, in particular to a method and system for eliminating multipath interference and carrier frequency offset. Background technique [0002] Quadrature Amplitude Modulation (QAM) is a combined amplitude and phase modulation technology, which uses the amplitude and phase of the carrier to transmit information at the same time, and is widely used in digital communications. The signal at the transmitting end will be affected after entering the channel, such as multipath interference, and an equalizer is needed to eliminate multipath interference; due to the different clock frequencies of the receiving end and the sending end, the carrier frequency of the receiving end is different from the local carrier frequency of the sending end. , there will be a residual carrier frequency deviation signal in the signal at the receiving end; in order to accurately obtain the original signal sent by the sending...

AI Technical Summary

Problems solved by technology

One is that the equalizer adopts a blind equalization algorithm, and the carrier synchronization circuit adopts a blind acquisition algorithm. This method can capture a relatively large range of frequency deviation of the carrier, and the frequency deviation that can be captured is as high as 5% of the symbol rate, but the output of the equalizer is wrong. There are many signals, and the error of the estimated frequency offset output by the carrier synchronization circuit is relatively large. The carrier synchronization circuit does not work at the beginning of this algorithm. After the equalizer works for a period of time and converges, the carrier synchronization circuit starts to work to capture the frequency offset. It is better Eliminate carrier frequency offset, its output signal is Z n , using the decider for Z n Estimate and get the estimated signal , because the blind acquisition algorithm of the equalizer is only compatible with the equalizer input signal X n related to the estimated signal irrelevant, so Z n The estimated signal of On the basis of better elimination of multipath interference, the joint effect of carrier synchronization circuit and equalizer can not be obtained more accurately Therefore, the bit error rate is relatively large. If it is different from the original signal at the transmitter, it is a bit error, and the bit error rate is the ratio of the total number of bit errors to the total number of symbols transmitted

The other is that the equalizer uses the symbol decision-assisted LMS algorithm, and the carrier synchronization circuit uses the symbol estimation auxiliary algorithm. The error of the estimated frequency offset obtained by the carrier synchronization circuit is relatively small, but the frequency offset range of the carrier that can be captured is also very small, which is not It is higher than 1% of the symbol rate. This is because the equalizer and carrier synchronization circuit need a process to reach the steady state of equalization convergence and carrier tracking. In the case of large frequency deviation, it does not reach the steady state when it starts to work. , the work of the equalizer and the carrier synchronization circuit makes the output of the decision device There are many wrong symbols in the carrier synchronization circuit, and the error of the frequency offset estimated when the carrier synchronization circuit uses the symbol estimation auxiliary algorithm is very large, resulting in the output There are more errors, and the equalizer uses symbol decision-assisted LMS algorithm on the basis of error symbols to obtain a large number of error output symbols, and even causes error diffusion, resulting in the equalizer not being able to converge and enter a stable state

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