Compensating Doppler shifts: Bringing High-Mobility to Wireless Communications
The invention describes a novel method to compensate Doppler shifts of at least one propagation path of an OFDM signal.
In the field of wireless communications, Orthogonal Frequency-Division Multiplexing (OFDM) has received much recent attention because of its high spectral efficiency, simple equalization, low complexity FFT based implementation, among other aspects. Therefore, many systems e.g., Digital Video Broadcasting (DVB), Digital Audio Broadcasting (DAB), Long Term Evolution (LTE), etc. are based on OFDM.
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However, there exist obstacles to high mobility in such systems, as OFDM is very sensitive to Doppler shift, where subcarriers are shifted causing an orthogonality loss in the receiver (inter-carrier interference, ICI). All known methods to cope with ICI are either very complex or inaccurate, and therefore inefficient in practice.
Our new compensation method is based on a sophisticated Matching Pursuit (MP) algorithm combined with an elaborate search algorithm to estimate time delays and the effect of the Doppler shifts, constituting a valid estimate of the channel response of the communication system. Consequently, the compensation of the signal can be reduced to the inversion of a circular channel matrix (estimate) based on FFT (of size N) with just O(N) operations. Hence, our inventive method outperforms state-of-the-art methods having a computational complexity between O(N2) and O(N3) apart from the channel estimation.
- reduced calculation complexity O(N) for the channel matrix inversion
- enhanced Matching Pursuit algorithm combined with elaborate dictionary search with reduced calculation complexity and increased accuracy
- applicability not dependent of the velocity of the moving receiver
- Compensation of the effects of Doppler-shifts with the transition of OFDM signals
Universität des Saarlandes Wissens- und Technologietransfer GmbH
Dr. Christof Schäfer
Universität des Saarlandes Wissens- und Technologietransfer GmbH, Campus, Gebäude A1 1
- EP 15701940 anhängig
Stichworteorthogonal frequency-division multiplexing, OFDM, Doppler shift, compensation, matching pursuit, LTE, DVB, DAB, fourier transformation, FFT