Method for pilot transmitting, channel estimation and noise power estimation in OFDM system

Abstract

The invention discloses a pilot signal transmitting method in an OFDM system, which is used for carrying out frequency domain windowing processing to pilot sequences and then transmitting. The invention also discloses a channel estimation method and a noise power estimation method, comprising the following steps of: receiving pilot signals processed by frequency domain windowing, carrying out channel estimation according to pilot sequences without windowing to determine an initial value HLS-W(k) of frequency domain channel response on each subcarrier corresponding to a user, and utilizing HLS-W(k) to determine corresponding channel time domain response hW(n); calculating signal power of channel time domain response with the index value of larger than NCP-W in the channel time domain response hW(n) as noise power of the system; setting the channel time domain response valve with the index value of larger than NCP-W in the channel time domain response hW(n) to be 0, completing denoising processing of channel estimation, carrying out Fourier transformation and dewindowing processing to CIR by denoising processing and obtaining the final frequency domain channel response of each subcarrier. The invention can improve accuracy of noise power estimation and channel estimation.

Description

technical field [0001] The present invention relates to technology in Orthogonal Frequency Division Multiplexing (OFDM) system, in particular to a pilot transmission method, a channel estimation method and a noise power estimation method in the OFDM system. Background technique [0002] OFDM technology is a multi-carrier digital modulation technology. Due to its high spectrum utilization, low cost, and good performance in multipath and mobile environments, OFDM technology is widely used in digital audio and video broadcasting, wireless local area network, LTE and other communication systems. [0003] OFDM technology uses multiple carriers with mutual orthogonal characteristics to improve frequency utilization. At the same time, through figure 1 The shown method of inserting a cyclic prefix (CP) effectively suppresses intersymbol interference caused by multipath. OFDM converts the high-rate data stream through serial-to-parallel conversion, so that the data symbol duration...

AI Technical Summary

Problems solved by technology

Usually, when channel noise power estimation and channel estimation are performed, the channel time-domain response outside the main lobe range (that is, outside the CP length) is treated as noise, and the noise power includes part of the CIR leakage energy, which affects The accuracy of noise power measurement also affects the denoising effect of channel estimation, which reduces the accuracy of channel frequency response on subcarriers

[0006] In addition, in a communication system using OFDM as the main multiple access technology, since the system bandwidth is usually shared by multiple users, for any user, the ratio between the total number of system subcarriers N and the number of occupied system subcarriers M The difference between them will be larger, so the energy leakage problem of CIR is also more serious

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