Low complexity channel estimation method based on orthogonal sequence design

Abstract

The method is used in MIMO-OFDM system having virtual carrier and comprises: the designed orthogonal training sequence is distributed in equal interval in valid sub-carrier on each transmitting antenna; they are pair-wise orthogonal and the rest is filled zero; the transmitting end intercepts a section from the time domain symbol obtained from inverse fast Fourier transform, adds a cycle prefix on it and then transmits it through antenna; the receiving end makes self-copy for the received time domain symbol and then converts it to a frequency domain symbol; the fast Fourier transform, over-sampling and the finite impulse response low-pass interpolating filer are used to make low complexity channel estimation.

Description

technical field [0001] The invention belongs to the technical field of MIMO-OFDM (Multiple-Input Multiple-Output-Orthogonal Frequency Division Multiplexing) communication, and in particular relates to a low-complexity channel estimation method based on orthogonal sequence design. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM, Orthogonal Frequency Division Multiplexing) technology has attracted more and more attention due to its high spectrum utilization rate and low implementation complexity. Since the 1980s, OFDM technology has not only been widely used in broadcast digital audio and video fields, but also has become a part of the wireless local area network standard. With the increase of people's demand for communication data, broadband, personalization and mobility, OFDM technology has been applied in many high-speed information transmission fields. At present, people are considering using OFDM technology MIMO (Multiple Input Multiple Out...

AI Technical Summary

Problems solved by technology

This method is simple to implement, but there are two inherent defects: one is that this method needs to transmit multiple continuous OFDM symbols, and in mobile time-varying channels, the channel information reflected in some transmission periods cannot reflect the continuous OFDM The symbols correspond to the frequency domain response statistics on the pilot subcarriers; the second is that each antenna selects different subcarriers to transmit pilots at the same time period, although mutual interference is avoided, it also leads to the loss of signal-to-noise ratio. N i When there are two transmitting antennas, it will cause a loss of 10log in the signal-to-noise ratio 10 N i dB

[0005] In addition, G.L.St "uber et al published "Broadband MIMO-OFDM wireless communications" in Proceedings of the IEEE, vol.92, No.2, pp.271-294.Feb.2004, using space-time coding structure to design MIMO-OFDM The disadvantage of the training sequence of the system is that too many OFDM symbols are used as the training sequence, and the performance loss is large in the time-varying channel

Z.Wu et al. published "Design of Optimal Pilot-tones for Channel Estimation in MIMO-OFDMSystems" in IEEE WCNC 2005, using the space-frequency coding structure to design the training sequence design of MIMO-OFDM systems. This method has advantages for time-varying channels Strong robustness, but the performance loss is serious when the channel order is large

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