Turbo iterative equalization detection method based on MCMC

Abstract

The invention discloses a turbo iterative equalization detection method based on MCMC. The method comprises the steps of establishing an OFDM (Orthogonal Frequency Division Multiplexing) system receiver model; determining prior distribution of channel impulse response, frequency domain interference signal variance and a frequency domain sending signal in an OFDM system; calculating conditional distribution of the channel impulse response, the frequency domain interference signal variance and the frequency domain sending signal; calculating estimated values of the channel impulse response and the frequency domain interference signal variance and a posterior probability of the frequency domain sending signal; carrying out iterative equalization processing to obtain a decoded output signal through utilization of a turbo iterative structure; and the like. According to the method, under the condition that impulse noise prior knowledge is unknown, the estimated values of the channel impulseresponse and the interference noise variance are obtained, moreover, the signal detection is realized, and the system reliability is improved. Influences of impulse noises on the OFDM system can be effectively suppressed, so the system performance is improved. The influences of the impulse noises can be eliminated, so the channel estimation precision is improved.

Description

technical field [0001] The invention belongs to the technical field of pulse noise interference removal of an orthogonal frequency division multiplexing system, in particular to an MCMC-based turbo iterative equalization detection method. Background technique [0002] Orthogonal frequency division multiplexing (OFDM) is a multi-carrier digital modulation technology, which has been widely used in wireless due to its advantages such as suitable for multi-path channel transmission, high spectrum efficiency, and convenient modulation and demodulation. communication systems and power line communication systems. [0003] figure 1 It is a schematic diagram of a currently commonly used OFDM system transmitter model, such as figure 1 As shown, the system sends a mutually independent binary bit sequence c, passes through a channel encoder with a coding rate R to obtain a coded bit sequence b, and then obtains an interleaved bit sequence d after passing through an interleaver, and mo...

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Problems solved by technology

[0023] However, the parameter method has two main problems: the difficulty in setting the optimal clipping threshold and the generation of subcarrier interference, which limits the further improvement of OFDM system performance.

In order to determine the optimal clipping threshold, the above-mentioned existing adaptive clipping threshold setting method based on the minimum bit error rate and the method of selecting clipping threshold based on time domain and frequency domain calculation all need to know the prior knowledge of the noise, when the noise When there is a deviation between the model and the power coefficient estimation, the optimal threshold cannot be obtained, which will lead to the deterioration of the overall system performance

In order to solve the problem of subcarrier interference caused by blanking, the existing iterative interference cancellation method mentioned above has the problem of slow convergence speed, which limits the application of this method

[0024] The compressed sensing method in the non-parametric method needs to meet the following constraints: the number of impulse signals in one OFDM symbol cannot exceed the minimum threshold of the number of Fourier transform points and the number of empty subcarriers. Due to the randomness of the impulse noise signal itself, the above Constraints limit the use of this method

Another method, the sparse Bayesian learning method, needs to know the state information of impulse noise and Gaussian noise when reconstructing the impulse noise signal, and the computational complexity is high, so it is difficult to apply in the actual system

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