Channel estimation method and apparatus based on OFDM system

Abstract

The invention relates to the wireless communication field, discloses a channel estimation method based on orthogonal frequency division multiplexing system and device thereof, which improves channel estimating precision and channel estimated performance. The method includes: selecting a plurality of pilot symbols form OFDM pilot symbols transmitted by a pilot frequency subcarrier to be measured, wherein, each pilot symbol is in corresponding to a channel coefficient of the pilot frequency subcarrier to be measured, obtained by preliminary estimating of the pilot symbol; filtering these channel coefficients obtained by preliminary estimating to obtain accurate channel coefficients of the pilot frequency subcarrier to be measured; performing frequency domain estimation according to the accurate channel coefficients, to obtain channel coefficients of non-pilot-frequency subcarrier to be measured. The selected pilot symbols are pilot symbols whose correlation coefficient is larger or equal to the prearranged threshold, in the received N pilot symbols, thereby correlation in time-domain is ensured by controlling the correlation degree of the selected pilot symbols.

Description

technical field [0001] The invention relates to the field of wireless communication, in particular to channel estimation technology based on an orthogonal frequency division multiplexing system. Background technique [0002] In recent years, a multi-carrier transmission technology represented by Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing, "OFDM") has attracted widespread attention. Multi-carrier transmission decomposes a data stream into several independent sub-streams, each of which will have a much lower bit rate. Using the low-rate multi-state symbols formed at such a low bit rate to modulate the corresponding subcarriers constitutes a transmission system in which multiple low-rate symbols are sent in parallel. [0003] As a multiplexing technique, OFDM multiplexes multiple signals on different orthogonal subcarriers. The bandwidth is divided into several sub-channels through traditional frequency division multiplexing (Freque...

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Problems solved by technology

[0010] An OFDM symbol usually contains a large number of subcarriers. Calculating the correlation matrix of the channel coefficients on these subcarriers and performing matrix inversion operations require a large amount of computation.

[0011] Moreover, this method uses the channel estimation result of the pilot position in a channel estimation time-frequency block to obtain the channel coefficient at the non-pilot position, which will cause the channel coefficient estimation of the current symbol to depend on the subsequent pilot symbol. It will bring a delay in channel estimation, and this does not conform to the construction principle of the actual filter

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