Article révisé par les pairs
Résumé : Emerging communication systems can benefit from time-reversal (TR) technology thanks to its goodspatio-temporal signal focusing effect. The recent advances in low-cost wideband devices fabricationfurther leverage the use of TR wideband communication systems. The TR is generally carried out inthe time domain and the focusing effect of TR comes from the use of a high transmit rate back-offfactor (BOF), which is the signal up-sampling rate. In spite of the widely-used orthogonal frequencydivisionmultiplexing (OFDM) modulation, few works have investigated the frequency-domain (FD) TRprecoding in combination with OFDM communication systems. Furthermore, most existing works onFD/TR precoding rely on multiple-antenna technology at the transmitter to create the focusing effect. Inthis paper, we investigate the focusing gain provided by TR precoding in multiple-input single-output(MISO) OFDM systems. In particular, we compare the communication performance of such system atthe intended position and that at the unintended position. Based on the analysis, we demonstrate thatincreasing the BOF and/or the number of transmit antennas significantly improves the focusing effectat the intended position. In contrast, the unintended positions receive less useful power. We deriveapproximated mean-square-error (MSE) expressions of equalized received signals at both intendedand unintended positions. The subsequent focusing gain is presented as a function of the BOF andthe number of antennas, enabling us to gain insights in the contributions of each parameter to thesystem performance. Numerical simulations with multi-path Rayleigh fading channels are carried outto validate the MSE expressions.

Documents en relation

DI-fusion