A Channel Estimation Method in Power Line Ofdm Communication System
A channel estimation, communication system technology, applied in distribution line transmission system, channel estimation, transmission system and other directions
Active Publication Date: 2020-02-18
北京中宸微电子有限公司
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[0004] In order to solve the channel estimation problem in the power line OFDM communication system, the present invention provides a low-complexity channel estimation method called polynomial expansion channel estimation, that is, on the basis of the existing LMMSE estimation, the P-order polynomial expansion is used to replace the LMMSE The inverse operation in the method, this method greatly reduces the computational complexity while ensuring the estimation accuracy
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[0031] The block diagram of pilot-based channel estimation in low-voltage power line OFDM communication system is as follows: figure 1 Shown:
[0032] At the sending end, the input binary bit information is first modulated into a frequency domain signal, and then the signal is converted into a parallel signal through serial-to-parallel conversion, and then an appropriate pilot frequency is inserted according to the characteristics of the power line communication system to obtain a new information sequence X m (k), assuming that the number of modulated subcarriers is N, X m (k) represents the information transmitted by the kth subcarrier on the mth OFDM symbol. After the IFFT operation, the frequency domain information is transformed into time domain information, and the output sequence x corresponding to the mth OFDM symbol is obtained m (n), then x m (n) is expressed as:
[0033]
[0034] In order to eliminate the inter-symbol interference ISI and inter-carrier interfer...
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The invention relates to a channel estimation method in a power line orthogonal frequency division multiplexing (OFDM) communication system. The channel estimation method comprises a first step of at a sending terminal, modulating information into a frequency domain signal, and converting the frequency domain signal into parallel signals; a second step of inserting a pilot, and converting the frequency domain information into time domain information after inverse fast Fourier transformation (IFFT); a third step of adding a cyclic prefix in the signal subjected to IFFT, so as to eliminate ISI and ICI in the OFDM system, entering a low-voltage power line channel after parallel to serial conversion, and arriving at a signal receiving terminal; a fourth step of removing the cyclic prefix at the receiving terminal, then performing FFT so as to obtain the frequency domain signal; and a fifth step of extracting information in a pilot position in the signal, performing channel estimation on the information, expanding a P-order polynomial to replace an inversion operation in an adopted linear minimum mean squares error (LMMSE) estimation method, and optimizing a coefficient of the polynomial so as to obtain a channel response estimation value in the pilot position. The channel estimation method can estimate a channel response value in the OFDM communication system effectively, improves the estimation accuracy and lowers the calculation complexity.
Description
technical field [0001] The invention relates to the technical field of communication, in particular to a channel estimation method in a power line OFDM communication system. Background technique [0002] Power line communication is a communication method that uses power lines as the medium to transmit data signals. It does not need to lay additional lines, which greatly reduces communication costs. However, due to the mismatch between the branch structure of the power grid and the impedance at the node, the power line communication channel has significant multipath characteristics, and Orthogonal Frequency Division Multiplexing OFDM (Orthogonal Frequency Division Multiplexing OFDM) technology can effectively overcome channel multipath delay, and spectrum utilization High rate, suitable for power line communication system. Not only does the power line channel have multipath effects, but the channel is a time-varying system, and the transfer function of the channel changes wi...
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IPC IPC(8): H04L25/02H04L27/26H04B3/54
CPCH04B3/54H04L25/024H04L25/0256H04L27/2628
Inventor 李桂林
Owner 北京中宸微电子有限公司