Guilherme R. Colen

Clustered-orthogonal frequency division multiplexing for power line communication: when is it beneficial?

This study presents a comprehensive analysis to highlight advantages and disadvantages, in terms of channel capacity and computational complexity (CC), of a so-called clustered-orthogonal frequency division multiplexing (OFDM) scheme for power line communication (PLC) technologies for access networks. By taking into account filtering, decimation and upsampling techniques, the implementations of two transmitter schemes, named 𝒫(·)-I and 𝒫(·)-II, and three receivers ones, named 𝒬(·)-I, 𝒬(·)-II and 𝒬(·)-III, that can be easily derived from the hermitian symmetric OFDM (HS-OFDM) scheme are discussed. Numerical results show that the clustered-OFDM schemes based on HS-OFDM provide the same bit-error-rate performance as that of HS-OFDM, double sideband-OFDM and single sideband-OFDM. Also, clustered-OFDM based on the combination of 𝒬(·)-II and 𝒬(·)-III offers the lowest CC for both baseband and passband data communications. Further, it is demonstrated that the clustered-OFDM schemes can trade off channel capacity for CC, which can give rise to low-priced transceivers for PLC technologies. Finally, a comparative analysis of clustered-OFDM and orthogonal frequency division multiple access (OFDMA) points out the scenarios in which clustered-OFDM can be competitive if the complexity of the OFDM transceiver is a primary consideration.

A temporal compressive resource allocation technique for complexity reduction in PLC transceivers

This work introduces a novel resource allocation technique for dealing with linear and periodically time-varying power line channels when an orthogonal frequency division multiplexing scheme is applied. By exploiting the correlations within one cycle of the mains signal, among cycles of mains signal and a combination of these connections, the proposed technique can offer three distinct trade-offs between computational complexity reduction and data-rate loss. Numerical results, which are based on measured data, are used to analyse these trade-offs, when these inter-cycle and intra-cycle relationship are taken into account. Also, we verify that the use of the normalised signal-to-noise ratio incurs very low performance degradation, and because of computational complexity rationale, its use is strongly recommended. Additionally, we show that those cases, in which the correlations among the cycles of the mains signal is relevant, offer the best trade-off between computational complexity reduction and data-rate loss. Finally, we show that the proposed technique can achieve the optimal data-rate and offers substantial improvements in terms of computational complexity when compared with existing approaches, including the Institute of Electrical and Electronics Engineers 1901 standard. Copyright

A Spectral Compressive Resource Allocation Technique for PLC Systems

This paper focuses on the benefits of the existing relationship among consecutive subchannels (spectral information) in a multi-carrier modulation-based power line communication system for reducing the computational complexity and signaling overhead associated with resource allocation techniques. In this regard, we introduce the spectral compressive resource allocation technique, which reduces the computational complexity and the signaling overhead by grouping subcarriers into chunks, whose length/bandwidth is defined with basis on the so-called normalized signal to noise ratio coherence bandwidth. Moreover, we address the combination of the proposal with another technique that exploits the existing temporal relationship within periodically time-varying power line channels. Based on a data set composed of in-home power line channel estimates and additive noise measurements, we quantify the tradeoff between computational complexity reduction and data rate degradation under distinct scenarios and conditions, and indicate circumstances in which the proposed technique is more useful. Finally, we show that the exploitation of both temporal and spectral information altogether results in more computational complexity reduction and/or less data rate degradation in comparison to other techniques.

A novel power line communication system for outdoor electric power grids

This paper outlines a novel power line communication (PLC) system that was specified, designed, and prototyped to address the features of low-voltage and outdoor Brazilian electric power grids when the frequency band between 1.7 and 50 MHz, which complies with the Brazilian regulation for broadband PLC, is considered. The proposed PLC system is constituted by a PLC base station and several PLC modems. Also, it makes use of the clustered orthogonal frequency division multiplexing scheme to divide the total frequency bandwidth into several subchannels (clusters). As a result, the maximum throughput achieved by a PLC modem is a fraction of the maximum throughput that a PLC base station can offer and, as a consequence, the computational complexity as well as hardware resource utilization demanded by a PLC modem is considerably reduced in relation to the PLC base station. Data-rate as high as 24 Mbps can be attained in each subchannel at the application level, finally, but not the least, this PLC system can be useful for smart grid communication and digital inclusion.

Statistical analysis and modeling of a novel parameter for resource allocation in multicarrier PLC systems

This work outlines a novel parameter that is capable of characterizing the flatness of the normalized signal-to-noise ratio for resource allocation purposes in power line communication (PLC) systems, which are based on multicarrier modulation schemes. This parameter, named normalized signal-to-noise ratio coherence bandwidth, can be used for grouping adjacent subchannels therefore reducing the computational complexity of resource allocation techniques. Additionally, we discuss a comparative analysis between the proposed parameter and the coherence bandwidth for resource allocation purposes, which leads us to conclude that the former is more appropriate than the latter for PLC systems. Moreover, we show a statistical analysis of the proposed parameter and model it with different distributions based on noise measurements and channel estimates of broadband in-home, outdoor, and hybrid PLC-wireless environments. On the basis of data sets obtained from measurement campaigns covering the frequency bands of 1.7 to 30, 1.7 to 50, and 1.7 to 100 MHz, we show that the best distributions for modeling the proposed parameter are inverse Gaussian, Nakagami, gamma, and Gaussian mixture, depending on the type of the channel (in home, outdoor, and hybrid PLC wireless) and the frequency band.

Resource allocation in OFDM-based PLC systems impaired by additive impulsive Gaussian noise

This work outlines a procedure for choosing the gap from the Shannon capacity curve in order to solve resource allocation problems in orthogonal frequency-division multiplexing-based power line communication systems impaired by impulsive Gaussian noise. In this regard, we perform statistical analyses of additive impulsive Gaussian noise models in order to measure the effect of the noise information on the proposed technique. Next, we solved resource allocation problems under symbol error rate constraint to verify the correctness of the proposed technique.

Narrow-band interference error correction in coded OFDM-based PLC systems

This work analyzes different error-correcting schemes for combating the effects of narrow-band interference in coded orthogonal frequency-division multiplexing-based narrow-band power line communication systems. In this sense, we analyze an error-correcting scheme widely acclaimed in the literature, which is constituted by the concatenation of a Reed-Solomon (RS) code, a convolutional code and an bit interleaver, and an alternative error-correcting scheme with less computational complexity composed of an RS code concatenated with a short block code. Base on a comparative performance analysis of both error-correcting schemes in terms of bit error rate, we conclude that the alternative error-correcting scheme offers satisfactory performance in terms of bit error rate and considerable computational complexity reduction when compared to the usual one.

A bit loading technique with reduced complexity for periodically time varying PLC channel

This paper focuses on a novel bit loading technique that is capable of reducing the computational complexity associated with the resource allocation in power line communication (PLC) system based on orthogonal frequency division multiplexing (OFDM) scheme. Basically, the proposed technique exploits the existing connection among microslots within one cycle and/or among consecutive cycles of the mains signal to trade computational complexity with data-rate when the channel is periodically time varying. Numerical results, which are based on measured data set, reveal considerable computational complexity savings with low probability of data-rate loss ratio and, as a consequence, the proposed technique can be useful to reduce hardware resource utilization in PLC transceiver based on OFDM scheme for in-home scenario.