Research Interests
MIMO Systems
Multiple-input multiple-output (MIMO) systems are studied in the context of multiple transmit and receive antennas. In particular we are looking at time varying linear transformation precoding and its application to turbo algorithms for MIMO systems. We are developing EXIT charts for analyzing these turbo space-time codes. We are also developing joint detection-estimation techniques for MIMO and MIMO-OFDM systems. This work is building on a large, but completed, effort for developing techniques and analyzing wireless systems with multiple antennas at the receiver only.
OFDM
We study algorithms for reducing the effect of deliberate clipping in OFDM systems. Clipping is an efficient and simple method to reduce peak-to-average power ratio (PAPR) of OFDM signals. However, clipping causes distortion and out-of-band radiation. We are designing iterative receivers that estimate and cancel the distortion caused by clipping noise.
Ultra-Wideband Communications
· Communications at Low-SNR
Current research at NJIT on ultra-wideband (UWB) ranges from fundamental to experimental. On the theoretical side we are looking into the fundamental properties of communications at low signal-to-noise ratio, such as UWB channel capacity, capacity of UWB MIMO systems, and limits on system performance in the absence of channel information.
· UWB Transceivers
We are designing adaptive Rake receivers for operation over time-dispersive channels and evaluating the effects of channel estimation errors on system performance. .
· UWB Antenna Design and Experiments
Experimentally, we are characterizing UWB channel properties with directional antennas. We are also developing a new design of an UWB antenna and testing it experimentally.
Cooperative Networking
Collaboration with Rick Blum\Lehigh U., Len Cimini\U. Del, Larry Greenstein\Rutgers
We are investigating cooperative relaying schemes in fading channels for various cases of available channel state information. We develop power allocation strategies that optimize the average and outage performance.
Radar
Collaboration with Rick Blum\Lehigh U., Len Cimini\U. Del, Eran Fishler, Reinaldo Valenzuela\Bell Labs.
It has been recently shown that multiple-input multiple-output (MIMO) antenna systems have the potential to dramatically improve the performance of communication systems over single antenna systems. Unlike beamforming, which presumes a high correlation between signals either transmitted or received by an array, the MIMO concept exploits the independence between signals at the array elements. In conventional radar, target scintillations are regarded as a nuisance parameter that degrades radar performance. The novelty of MIMO radar is that it takes the opposite view, namely, it capitalizes on target scintillations to improve the radar’s performance. We are currently studying applications of MIMO to diversity, resolution and tracking in radars.
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