Time-Reversal MIMO OFDM Green communicAtions based on MicRo-structured ANtennas – TRIMARAN

OFDM-MIMO systems are efficient for wireless communications in terms of throughput versus transmit power. Many algorithms have been developed in the physical layer and joint MAC-PHY layers, for both TDD and FDD, in order to achieve the MIMO capacity under maximum transmit power constraint. MIMO-OFDM techniques are theoretically scalable with the number of antennas and the number of sub-carriers.
However, in practice, expected performance is not met due to complexity constraints and implementation impairments. MIMO-OFDM receivers performance prediction is highly complex for large number of antennas and sub-carriers, dispersive channels, and large multi-user or multi-stream interference. Low complexity but unreliable PHY layer performance predictions leads to suboptimal link adaptation and scheduling by MAC layer.
The system lacks of robustness.
Among all MISO beamforming techniques, time reversal (aka matched filtering transmission) appears to be one of the most robust techniques. It is less complex at the transmitter than Zero-Forcing Beamforming (a.k.a inverse filtering) and yet, it leads to a decreasing receiver complexity. Its achieved space-time focusing quality increases in highly scattering environments. Applied alone, time reversal is optimum in the low SINR region (high multi-user interference or low receive power). Combined with coded OFDM and STBC, it meets coded classical beamforming (based on the determination of the unique eigen vector of the MISO channel) performance with lower complexity. Combined with spatial multiplexing, and micro-structured antennas, it achieves MIMO multi-stream communications by sub-wavelength focusing.
Combining OFDM-MIMO, Time Reversal and micro-structured antennas is still to be done.

The aim of this project is to achieve high throughput and high system robustness, in wireless networks, under a maximum transmit power consumption constraint, with large bandwidth and very large numbers of antennas over small terminals and access points, in indoor and indoor-outdoor environments which are highly scattering, and taking into account radio conditions variations due users low speed or due to changing environment.
The project proposes a joint design of OFDM-MIMO and space-time focusing with micro-structured antennas. Focusing quality will be controlled for a better robustness of the receiver performance against implementation impairments and multi-path propagation. Innovative algorithms based on time reversal and space-time focusing techniques will be proposed and evaluated by link and system level simulations. New metrics to measure robustness and human exposure, in addition to traditional metrics, will be defined.
Finally, the most important challenge of this project is to produce an experimental prototype which will provide a proof-of-concept of data transmission with a maximum bandwidth of 40MHz, OFDM-MIMO, time reversal, and NTxNR micro-structured antennas. The prototype will include up to NT=8 transmit antennas and up to NR=4 receive antennas.