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Inbar Fijalkow's HomePage

Inbar Fijalkow,
ETIS, UMR 8051,
6, avenue du Ponceau,
F-95000, Cergy-Pontoise,
Tel: (+33) 1 30 73 66 10
Fax: (+33) 1 30 73 66 27

Signal processing for digital communications
My research interest is in signal processing for digital communications.
Starting from blind equalization and sources separation to mitigate multipath propagation in hostile environments, I enlarged the transmission problems I considered at the same time I learned about communication systems. I also considered multi-user systems based on spread-spectrum such as HS-DPA or GPS in multipath propagation, multicarrier systems such as UWB based on multi-band OFDM, and OFDMA for LTE.

Turbo-processing: turbo-equalization, Hybrid-ARQ
Thanks to Alain Glavieux, I got interested in turbo-equalization, i.e. joint equalization and decoding using soft information passing in an iterative processing. We proposed an original analysis of the turbo-equalizer and proposed joint channel estimation inside the turbo-equalizer. The application to Hybrid-ARQ (retransmission strategy) has also been developped.

Resources allocation with limited channel state information
This first joint approach led me to consider the transmission more globally in a cross-layer fashion. Therefore, I started to deal with resources allocation (of subcarriers, bands, power, modulation order, code rate...) that can be performed from the study of the system performance. The originality of the approach I considered is to consider a very limited channel state information based on the mean channel gain over some band in order to have a low feedback throughput.

Dirty RF
Considering the entire transmission chain, it also important to deal with the effect of the RF frontal which is never totally ideal. Non-linearities, frequency selectivity, mis-synchronisation (IQ-imbalance or carrier frequency offset) impact heavily on the system performance. We analyze these "dirty-RF" impairments and propose numerical processing to mitigate their effects.