Broadband PLC channel estimation and equalization techniques

HADAD, M.; FUNES, M.; DONATO, PATRICIO G.; MOYA, S.

Advances in Engineering Research

Nova Science

Lugar: Nueva York; Año: 2020; p. 101 - 133

During recent years, high-speed broadband power line communication (BB-PLC)over low voltage networks have become an option worth of consideration forresidential data transmission. This technology has specific standards that take intoaccount the modulation technique, among other things. Multi-carrier systems, likeorthogonal frequency-division multiplexing (OFDM), or alternatively the use ofsingle-carrier are mainly considered. Both modulation schemes require the use ofchannel estimation and equalization techniques in order to mitigate the effect ofthe physical medium on the transmitted signal, which behaves like a time-variantmultipath channel that severely distorts the transmitted signal. The equalizationcan be performed in the time or frequency domain, with time domain equalizationtechniques often requiring more processing load than frequency domain techniques.To perform frequency domain equalization (FDE), a cyclic prefix is added to thetransmitted signal to transform the effect of the channel into a periodic signal, allowingto process the data packet with a Discrete Fourier Transform (DFT), minimizing thecalculation errors as long as the prefix is longer than the channel impulse response.A crucial part of the equalization process is the correct identification of the channelresponse, since it is required for the calculation fo the equalization term. Thereare several techniques in the literature that allow to obtain the channel responsedynamically, which is a requirement because the channel is time-variant. Thischapter will show frequency domain equalization techniques for single-carrier and OFDM. The described techniques are classic approaches like least squares (LS) andLinear Minimum Mean-Square Error (LMMSE) for OFDM, Zero-Forcing (ZF) andMinimum Mean-Square Error (MMSE) for single carrier, and two different approachesbased on the use of Complementary Sets of Sequences as pilot symbols, one for OFDMand one for single carrier. All the methods will be compared considering the Bit ErrorRate (BER) with respect to Signal-to-Noise ratio (SNR) of transmissions over realisticsimulations of PLC channels. The channel simulations are composed by time-varyingchannel response models and Middleton Class-A noise, which is considered as themodel closer to the real PLC noise. The shown methods are also compared over a realdata transmission, using the number of received errors as the comparison metric.