Anil Mengi

Successive impulsive noise suppression in OFDM

We consider orthogonal frequency division multiplexing (OFDM) for high data rate narrowband power line communication (PLC) in the frequency bands up to 500 kHz. In narrowband PLC, the performance is strongly influenced by the impulsive noise with very large amplitudes with short durations. Simple iterative impulsive noise suppression algorithms can effectively improve the error rate performance in OFDM systems. However, the convergence speed depends on the number of subcarriers, N. For N ≤ 256, the algorithms converge slowly or not even at all. In this paper, we extend the iterative receiver design to enable a fast convergence for N ≫ 64 and to improve the error rate performance for N ≤ 64. These extensions include 1) a clipping and nulling technique at the input of the iterative algorithm 2) a novel low complexity syndrome decoder which uses the redundancy that is transmitted for synchronization or other purposes. Simulation results are provided to show the improvement in error rate

Analysis of the devolo's 500 kHz G3-PLC access technology based on smart grid field trials

In the smart grid, the G3-PLC solution is in direct competition with other IP-based communications technologies such as GPRS or DSL. In this paper, we present the devolos 500 kHz G3-PLC access technology and its analysis based on smart grid field trials in Germany. The focus of the analysis in this paper is concentrated on the following parameters: The influencing factor of near and far transmission throughput, the influence of a repeater on the throughput, and the influence of different UDP packet size on the throughput.

Coded Frequency Modulation with RLL Sequences for CENELEC Band Applications

This paper addresses low frequency range power-line communications (PLC), where the transmitters are output voltage and bandwidth limited. We propose an efficient transmission method of combining Reed Solomon (RS) coding with run length limited (RLL) codes. Our proposed transmission model consists of three main parts: RS encoder followed by a one or two bit(s) look-ahead RLL encoder and 2-FSK modulator. The resulting transmission has a constant envelope signal modulation, no bandwidth expansion and more concentrated spectra in the carrier frequencies. This is an important result, directly applicable to the CENELEC band. In addition, a soft decoder based on minimum distance criteria for the RLL codes is introduced to yield an additional coding gain. We present the spectral analysis of RLL coding. Finally, the performance of the detectors is analyzed theoretically as well as through simulations.

500 kHz G3-PLC access technology for the roll-outs in Germany

The development of smart grid triggered more and more demand for high reliable communication technologies. Powerline communication is the only access technology that uses the topology of the power distribution network. Since 2005, OFDM based access PLC technologies have issued different products and standards allowing reliable high data rate com- munications between transformer substations and meters. This paper evaluates the powerline communication for the deployment in Germany. We conclude that the development of PLC communication network using the 150-500 kHz fulfills the requirements and offers cost advantage solution.

Impulsive noise error correction in 16-OFDM for narrowband power line communication

Orthogonal frequency division multiplexing (OFDM) with a small number of subcarriers (≤ 64) is shown to be promising in the narrowband power line communication (PLC) when the peak-to-average power ratio is reduced to the CENELEC standards. Although many authors studied the performance of the OFDM systems under the impulsive noise, their considerations are mostly restricted to OFDM systems with a large number of subcarriers. In that case, discrete Fourier transform (DFT) spreads the impulsive noise in such a way that its distribution in the frequency domain can be approximated as Gaussian. If the number of subcarriers is small, these methods can be hardly used. We describe an iterative algorithm for correcting the impulsive noise erors for the OFDM transmission with a small number of subcarriers. Simulation results for a 16-OFDM-QPSK systems show that the influence of impulive noise can be essentially reduced.

Electromagnetic compatibility in Europe for OFDM based PLC access data transmission in the frequency range 150 kHz to 500 kHz

Electromagnetic Compatibility (EMC) is a key consideration for the development and operation of Power Line Communication (PLC) systems. Applicable EMC requirements and related standards may change depending on the considered regulatory regions (typically Japan, the United States and Europe have different regulations). This white paper focuses on EMC aspects to be considered for PLC roll-outs in the European market in the frequency range 3 kHz to 500 kHz.

Coded modulation with a constraint on the minimum channel symbol duration

A coded modulation scheme is described which improves the error performance of constant envelope data transmission without requiring more bandwidth. This is achieved by controlling the minimum channel symbol duration by run-length limited (RLL) encoding. It is shown that the same amount of information can be transmitted within the same minimum channel symbol duration with a coding gain of 4 dB compared with the uncoded modulation. The bandwidth is analyzed using the power spectra of channel signals. As a practical application, we consider bandwidth limited transmission with a restriction on the maximum transmitted power. Following a discussion of a coded modulation principle, constructed RLL codes and the evaluation of their code performances are provided, and the simulation results for BPSK and 2-FSK modulations are presented. Comparisons are strictly made on the basis of equal information rate and the same minimum channel symbol duration.

Maximum-likelihood block decoding of noncoherent coded FSK for the CENELEC band

This paper addresses low frequency range power line communications (PLC), where the transmitters are output voltage and bandwidth limited. We investigate the block decoding of coded non-coherent 2-FSK modulation for the transmission over the impulsive noise channel with narrow band interference. The maximum-likelihood (ML) receiver is analyzed and suboptimum decoding algorithms improving the bit error rate performance are derived. Furthermore, an efficient transmission method of combining Reed Solomon (RS) coding with run length limited (RLL) codes is incorporated to obtain coding gain without expanding the bandwidth. Simulation results show the improved performance of the proposed RS-RLL scheme. Our coding/modulation scheme is in agreement with the existing CENELEC standard.

IEEE 1905.1 hybrid home networking standard and its implementation with PLC, Wi-Fi and Ethernet technologies

This paper considers “hybrid networking” with a convergence mechanism at layer 2.5 as addressed by the IEEE 1905.1 standard. The developed hybrid infrastructure network provides a seamless integration of three different communication technologies: Ethernet, Wireless LAN, and Power line Communication (PLC). The network enables a global view of the network topology regardless of the technologies running in the home network. Among other functions, it allows the use of parallel links to transmit flows and to reroute traffic in case of links degradation or failure. The major benefits of this implementation include the ease of use for the end users, the auto network configuration, the improved network diagnostic and the increased robustness.

Constrained coded modulation in the time domain

We describe the application of constrained coded FSK-modulation in the time domain. We combine error correcting codes and Run Length Limited RLL-codes before FSK modulation to obtain a system where we have almost no change in the Power Spectral Density function but a net positive coding gain as for coded modulation invented by Ungerböck. The RLL-code is designed in such a way, that the minimum spacing between two transitions is the same as for the uncoded symbol duration. Furthermore, the RLL-codes have a minimum distance larger than 1 to also allow for soft decision RLL decoding. We give the performance for a Reed-Solomon error correcting code of length 255 symbols of 8 bits. The overall coding gain obtained is about 4 dB.