Coordinated cancellation and correction of non-stationary noise in OFDM
Final Report Abstract
The first two phases of the project started from actual measurements of impulse noise with an antenna array of 4 antennas in the wireless LAN range. This was modeled by Middleton Class-A. Non-linear detection was improved and compared to standard clipping and blanking approaches. Mitigation of impulse noise using multi-antenna dependencies, diversity reception, space-time coding, amplify-and-forward relaying, and as a special case, aeronautical distance-measuring signals were studied. These first steps were kind of almost solely communications-based, especially also studying OFDM systems. Applications of coding were still limited. The third phase now simplified the transmission system to 2-PSK, but concentrated on the combination of impulse-noise estimation intertwined with LDPC decoding. Here, we still used the Middleton Class-A model with two Markov states, which was already found to be sufficient in the earlier phases of the project. A Viterbi decoder was used to estimate the state to be impulsive or impulse-free, which determines the standard deviation of the disturbance. This standard deviation is included into the intrinsic information of the LDPC decoding, which itself provides a data estimate (mean) to again be used inside the Viterbi algorithm. This establishes an atypical Turbo-like procedure, where two different parameters are exchanged. We found that additional interleaving is essential to make sure that identical or similar variable node degrees are not hit by an impulse burst. We compared results to simplified threshold decisions or weighted sum-based ones, which, as expected, proved the superior performance of the trellis-based iterative state estimation. An also intended direct integration of the state estimation into the LDPC Tanner graph proved to not be possible, since this would have to be based on a hard decision at a previous state, which was found to not be sufficiently reliable.
Publications
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“A receiver design for MIMO systems over Rayleigh fading channels with correlated impulse noise,” 2012 IEEE Global Communications Conference (GLOBECOM), Anaheim, CA, 2012
Saaifan, Khodr A. & Henkel, Werner
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“Efficient nonlinear detector of binary signals in Rayleigh fading and impulsive interference,” 2012 IEEE 76th Vehicular Technology Conference (VTC2012-Fall), Quebec City, Canada, 2012
Saaifan, Khodr A.; Hassan, Khaled & Henkel, Werner
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“A nonlinear diversity combiner of binary signals in the presence of impulsive interference,” IEEE ICC 2013, Budapest, Hungary, 2013
Saaifan, Khodr A. & Henkel, Werner
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“Decision boundary evaluation of optimum and suboptimum detectors in class-A interference,” in IEEE Transactions on Communications, vol. 61, no. 1, pp. 197-205, Jan. 2013
Saaifan, Khodr A. & Henkel, Werner
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“Cancellation of distance measuring equipment interference for aeronautical communications,” in IEEE Transactions on Aerospace and Electronic Systems, vol. 53, no. 6, Dec. 2017
Saaifan, Khodr A.; Elshahed, Ahmed M. & Henkel, Werner
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“Impulse noise modeling and mitigation for OFDM systems,” in ITG Fachgruppe “Angewandte Informationstheorie” Bremen, 2017
K. A. Saaifan and W. Henkel
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“Lattice coding for MIMO systems in impulse noise,” 2017 The 9th International Congress on Ultra Modern Telecommunications and Control Systems (ICUMT), Munich, 2017
Saaifan, Khodr A.; Islam, Nazia & Henkel, Werner
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“Measurements and modeling of impulse noise at the 2.4 GHz wireless LAN band,” 2017 5th IEEE Global Conference on Signal and Information Processing, Montreal, Canada, 2017
Saaifan, Khodr A. & Henkel, Werner
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LDPC codes incorporating source, noise, and channel memory, PhD Thesis, Jacobs University Bremen, 2022
N. S. Islam
