Reducing the probability of sync-word false acquisition with Reed-Solomon codes

In our previous work we introduced a method for avoiding/excluding some symbols in Reed-Solomon (RS) codes, called symbol avoidance. In this paper, we apply the symbol avoidance method in sync-word based synchronization of RS encoded data. With the symbol avoidance method we reduce the probability of the RS encoded data being mistaken for the sync-word used to delimit the start/end of the data. The symbols in the RS code are avoided according to the sync-word used, such that the sync-word has very low probability of being found in the RS codewords, where it was not inserted. Therefore, for different sync-words, different symbols need to be avoided in the RS code. The goal here is to reduce the probability of false acquisition of the sync-word in the RS encoded framed data

Application of symbol avoidance in reed-solomon codes to improve their synchronization

Abstract: In our previous work we introduced a method for avoiding/excluding some symbols in Reed-Solomon (RS) codes, called symbol avoidance. In this paper, we apply the symbol avoidance method to make synchronization of RS encoded data more effective. We avoid symbols in a RS code and then perform conventional frame synchronization on RS encoded data by appending sync-words on the data. The symbols in the RS code are avoided according to the sync-word used, such that the sync-word has very low probability of being found in the RS codewords, where it was not inserted. Therefore, for different sync-words, different symbols need to be avoided in the RS code. The goal here is to reduce the probability of mistaking data for the sync-word in the RS encoded framed data. Hence, the probability of successful synchronization is improved. Not only does our symbol avoidance code improve probability of successful synchronization, it also reduces the overall amount of redundancy required when the channel is very noisy

The effects of periodic impulsive noise on OFDM

Abstract: The effect of periodic impulsive (short duration) noise on OFDM is investigated. We present results on the nature of periodic impulsive noise, showing that the PDF of periodic impulsive noise is not exactly Gaussian. We also present results showing that periodic impulsive noise can be more devastating to OFDM compared to random impulsive noise. This is because periodic impulsive noise energy is not spread by the FFT on the receiver side of the OFDM, instead it appears periodic in the frequency domain. Results showing the effect of nulling to mitigate periodic impulsive noise are presented. We suggest a simple short block code (as opposed to long block codes) that can effectively combat the effects of periodic impulsive noise

Segmental analysis of the transmission in CSK systems based on the Euclidean distance

Abstract: This article presents a segmental analysis of the transmission in colour shift keying (CSK). The Euclidean distance is fractionally studied to find the distance limits between the observed and the expected points. Practical segmental characterisation of the CSK receiver is presented to verify the Voronoi segmentation over the CSK channel and confirm crosstalk and correlation between the red, green and blue channels based on the threshold selection

Density operator of a system pumped with polaritons: A Jaynes-Cummings like approach

We investigate the effects of considering two different incoherent pumpings over a microcavity-quantum dot system modelled using the Jaynes-Cummings Hamiltonian. When the system is incoherently pumped with polaritons it is able to sustain a large number of photons inside the cavity with Poisson-like statistics in the stationary limit, and also leads to a separable exciton-photon state. We also investigate the effects of both types of pumpings (Excitonic and Polaritonic) in the emission spectrum of the cavity. We show that the polaritonic pumping as considered here is unable to modify the dynamical regimes of the system as the excitonics pumping does. Finally, we obtain a closed form expression for the negativity of the density matrices that the quantum master equation considered here generates.Comment: 16 pages, 4 figure

Selected subcarriers QPSK-OFDM transmission schemes to combat frequency disturbances

To combat the impairments caused by frequency disturbances in the power line communications (PLC), a modified conventional QPSK-OFDM transmission scheme is presented. The idea of this scheme is to first group the N OFDM subcarriers into groups of M and then transmit data by selecting a subset of the subcarriers in the group. Real and imaginary parts of QPSK symbols are independently assigned to the selected subcarriers in a group, such that the minimum squared Euclidean distance is maximised. With this kind of symbol assignment to subcarriers our scheme has no net loss in terms of SNR requirements, in AWGN, in comparison to the conventional QPSK-OFDM, even though it has half the data rate of the conventional QPSK-OFDM. We refer to the conventional QPSK-OFDM as Scheme A. Our scheme displays a superior performance over Scheme A and another scheme (Scheme B), in the presence of frequency disturbances and also frequency selective fading noise. We further modify Scheme B and come up with additional two new QPSK-OFDM schemes that have better performance than Scheme B in AWGN and impulse noise. To encode, we apply a (n, k) RS code and a simple permutation code on the conventional QPSK-OFDM scheme, which significantly improves the decoder's performance in the presence of frequency disturbances. A simple narrow band noise model is developed and presented

Noise generated by modern lamps and the influence on the smart-grid communication network

Abstract: The metal halide lamp is a high energy electric lamp that produces visible light by an electric arc tube and it is a type of high-intensity discharge (HID) that contains a fused quartz and mixture of gases. These lamps inject noise into the smart-grid power line communications (PLC) network. This can have a strong and negative effect when using the PLC system to control the automatic switching of lamps in public places. In this paper we investigate the effects when the metal halide lamps with electronic or electromagnetic ballasts are seen as noise sources on the smart-grid power line network. It is shown that in the CENELEC band: (3 kHz – 150 kHz) the interference level from metal halide lamps is significantly below the allowed maximum PLC signal levels. In the band 150 kHz – 30 MHz however, PLC signals compete with Electromagnetic Compatibility (EMC) levels. The operational methods of the electronic and electromagnetic ballasts when connected to the metal halide lamps are explained

Low-complexity SOCPBFSK-OOK interface between PLC and VLC channels for low data rate transmission applications

This paper studies and proposes a low cost low complexity interface between power line communications (PLC) and visible light communications (VLC) for low data rate transmission applications. The discussion presents the performance of a spread orthogonal continuous phase binary frequency shift keying (SOCPBFSK) receiver combined with an on-off keying (OOK) modulator to relay low data transmission between PLC and VLC channels. The characteristics of the interface are presented. The results of an experimental test using the proposed interface over the European Committee for Electrotechnical Standardization (CENELEC) bands C and D are presented. The eye diagrams of the combined error are presented as well

On mercury vapor lamps and their effect on the smart-grid PLC channel

Abstract: The mercury vapor lamp is the oldest high intensity discharge technology lamp that uses an electric arc, and comes in different shapes and designs. It creates a very bright light by using an arc through vaporized mercury in a high pressure tube. This lamp can cause unwanted interference to the smart-grid network or power line communications channel when connected to the channel’s wiring system. In this paper we investigate the negative effects that the mercury vapor lamps with electric ballast have on the smart-grid PLC channel. This can have a strong and negative effect when using the smart-grid PLC network to control the automatic switching of lamps in public places. The narrowband and broadband channels are investigated where the interference level from mercury vapor lamps is significantly below the allowed maximum PLC signal levels on the band: (3 kHz – 150 kHz), and competes with Electromagnetic Compatibility (EMC) levels on the 150 kHz – 30 MHz band. The mercury vapor lamp uses an electric ballast to connect to the powerline system. This connection is explained in detail