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Actualités de l'école

13/12/2019

Soutenance de doctorat de Safa NAJJAR



Soutenance de thèse de doctorat le  13/12/2019 à 09H30 à l'amphi Ibn Khaldoun de SUP'COM.

 

Intitulé : Optimized Narrowband Power Line Communication Scheme Robust to the Attenuation and Noise Effects of the Channel


Présentée par :  Safa NAJJAR




JURY


Président

M. Slim REKHIS

Professeur, SUP'COM

 

 

 

Rapporteurs

M. Jalel BEL HADJ SLAMA

Professeur, ENISO

 

Mme Ines KAMMOUN JEMAL

Professeur, ENIS

 

Examinateur

M. Fethi TLILI

Maître de Conférence, SUP’COM

 

 

 

Directeur de Thèse :

M. Adel GHAZEL

Professeur, SUP'COM


Abstract:

Narrow-band powerline communication (NB-PLC) offers an excellent opportunity to enable Smart Grid and smart cities. They were not fully taken advantage of due to the competition with low-cost wireless solutions. Besides, the harsh channel and noise conditions, as well as the lack of their characterization and modeling studies in the low frequencies, slowed their development.  Currently, more attention is given to multi-carrier systems, characterized by their high data rates and high complexity, which are not suitable for the requirements of the home automation applications.

In this thesis, the design of a communication scheme, gathering low complexity and high performance, is proposed. The proposal of this scheme was based on a previous characterization study that allowed a good understanding of the NB-PLC channel. The different stages of the designed modem were tested under the harsh channel conditions to be validated.

The first step was the selection of the mono-carrier modulation technique. Frequency shift keying (FSK) was widely used in the literature because it meets these needs. Although the binary systems did not have the best performances in terms of bit error rates (BER), the use of the quaternary modulation justified our choice.  In the CENELEC band, the quaternary FSK and spread FSK (SFSK) reached BER = 10-4 at a signal-to-noise ratio (SNR) of 25 dB under the PLC channel attenuation and impulse noise effect. In the FCC band, the error floor of the quaternary SFSK is 5×10-4. Then, we proposed to add a bloc of permutation code to the modulator to immunize the communication system to the channel impairments. This scheme is not widely used in practical implementation due to the complexity of the commonly used decision methods studied in the literature. For that end, we recommend a new simple decoding rule for permutation codes inspired by the classical FSK decision. We showed, analytically and by simulation, its performances in terms of decision accuracy, in comparison with the soft decision method. The binary coded modulation did not bring a coding gain in the low SNRs but improved the error floor, caused by the impulse noise presence, of the coded system. The quaternary coded FSK showed that the error floor almost disappears in the CENELEC band. Finally, the addition of a short block code was investigated. The design parameters of a Bose–Chaudhuri–Hocquenghem (BCH) and Reed-Solomon (RS) codes were chosen based on their capacity to mitigate the impulse noise (IN) effect. A simple 2-error correcting BCH code showed effective in mitigating the error floors and the high attenuation effect. A bit error rate equal to 10-5 was obtained at SNR = 15 dB for both CENELEC and FCC bands. The use of syndrome decoding for the BCH code allows simple decoding with low implementation complexity.

Keywords: Power Line Communication, Smart Grid, Home Automation Applications, channel attenuation, impulse noise, error floor, modulation, FSK, SFSK, permutation code, select largest, channel coding, BCH, RS.