Importance of Symbol Equity in Coded Modulation for Power Line Communications

The use of multiple frequency shift keying modulation with permutation codes addresses the problem of permanent narrowband noise disturbance in a power line communications system. In this paper, we extend this coded modulation scheme based on permutation codes to general codes and introduce an additional new parameter that more precisely captures a code's performance against permanent narrowband noise. As a result, we define a new class of codes, namely, equitable symbol weight codes, which are optimal with respect to this measure

Elusive Codes in Hamming Graphs

We consider a code to be a subset of the vertex set of a Hamming graph. We examine elusive pairs, code-group pairs where the code is not determined by knowledge of its set of neighbours. We construct a new infinite family of elusive pairs, where the group in question acts transitively on the set of neighbours of the code. In our examples, we find that the alphabet size always divides the length of the code, and prove that there is no elusive pair for the smallest set of parameters for which this is not the case. We also pose several questions regarding elusive pairs

Product Construction of Affine Codes

Binary matrix codes with restricted row and column weights are a desirable method of coded modulation for power line communication. In this work, we construct such matrix codes that are obtained as products of affine codes - cosets of binary linear codes. Additionally, the constructions have the property that they are systematic. Subsequently, we generalize our construction to irregular product of affine codes, where the component codes are affine codes of different rates.Comment: 13 pages, to appear in SIAM Journal on Discrete Mathematic

Diagonally Neighbour Transitive Codes and Frequency Permutation Arrays

Constant composition codes have been proposed as suitable coding schemes to solve the narrow band and impulse noise problems associated with powerline communication. In particular, a certain class of constant composition codes called frequency permutation arrays have been suggested as ideal, in some sense, for these purposes. In this paper we characterise a family of neighbour transitive codes in Hamming graphs in which frequency permutation arrays play a central rode. We also classify all the permutation codes generated by groups in this family

Evaluation of mixed permutation codes in PLC channels, using hamming distance profile

Abstract: We report a new concept involving an adaptive mixture of different sets of permutation codes (PC) in a single DPSK-OFDM modulation scheme. Since this scheme is robust and the algorithms involved are simple, it is a good candidate for implementation for OFDM-based power line communication (PLC) systems. By using a special and easy concept called Hamming distance profile, as a comparison tool, we are able to showcase the strength of the new PC scheme over other schemes reported in literature, in handling the incessant noise types associated with PLC channels. This prediction tool is also useful for selecting an efficient PC codebook out of a number of ! similar ones

Frequency optimization for narrowband power-line communications

Abstract: Optimized frequency tones for the power line channel is presented from an experimental scenario. Four sets of frequency tones, grouped according to CENELEC’s regulation on frequency use for narrow band power line applications are selected according to their signal-to-noise ratio (SNR) performance. COMBLOCKS, a prototyping hardware was used for the implementation. Often times, M-FSK/OFDM have been presented and used as the modulation scheme of choice for power line communications (PLC), the choice of best frequencies to use is however, an area that has hardly been explored. This paper is concentrated on the choice of such optimal frequencies