Dr. Bergel's Lab
Dr. Itsik Bergel of the Faculty of Engineering develops methods for interference mitigation in wireline and wireless communication systems. His research focuses on the use of limited cooperation between terminals to increase the data rates of all users in the network.
Dr. Bergel’s methods bridge the gap between the ideal performance predicted by theory – which, because of computational complexity, cannot be achieved in the real world – and modern, state-of-the-art communication systems. His techniques can be applied to various platforms, including DSL wireline systems and wireless add-hoc networks (such as wireless LAN).
Asymptotic Performance of Ad-Hoc Networks with Multiple Antennas
The performance of wireless ad hoc networks is mostly limited by the self interference caused by the network members.
Dr. Bergel’s team explores the effect of various transmission strategies on the network interference, and the resulting transmission capacity of slotted ALOHA and slotted CSMA networks. The analysis is based on a Poisson point process (PPP) shot noise model for the aggregate interference. The resulting achievable rates are used to study the effect of interference mitigation on multi-hop wireless ad hoc network.
Efficient Multi-Antenna Communication Schemes in Cognitive Radio
Cognitive radio networks allow secondary users to share the spectrum of primary users under an interference limit constraint.
Dr. Bergel’s group studies the performance of multi-antenna cognitive networks under various transmission schemes. In particular, they quantify the effects of imperfect channel state information (CSI), and derive low complexity robust transmission schemes that can achieve near optimal rates with imperfect CSI.
Communication over Unknown Channels
Although communication systems are often analyzed under the assumption of some prior knowledge of the channel, this is rarely the case in practical systems, which usually need to estimate the channel from the received signal.
Dr. Bergel and his team derive bounds on the capacity of non-coherent channels. Through these bounds they define and study the effective coherence time of the system. While their current projects derive bounds for single antenna OFDM systems, they intend to study MIMO systems and multiple access systems as well.
Adaptive Precoding for Multi-User Interference Mitigation in DSL Systems
Dr. Bergel’s group investigates the performance of an adaptive downstream multichannel VDSL precoder that is based on error signal feedback.
The precoder has been shown to completely suppress far end cross talk (FEXT) in a static scenario. Their analysis presents sufficient conditions for precoder convergence and a steady state error analysis for various configurations, including partial FEXT cancellation and low rate quantization of the error signal feedback.