Kriging was originally developed for geographical interpolation purposes, but has proven to be a powerful tool in many other applications as well. In this study we evaluate kriging for Wi-Fi signal strength estimation in three different complex indoor environments. The empirical investigation of several scenarios is described and the results are analysed. Kriging is shown to be an efficient method for RSSI estimation in complex environments with acceptable results and can be used to construct realistic coverage maps with little effort.

We derive a simple formula to generate a wide-sense systematic generator matrixBfor a Reed-Solomon code. Specifically, we generate the generator matrixBsuch that the columns with indices ¿1, ¿2,..., ¿kare the columns of the identity matrixIk. One possible application of these wide-sense matrices is erasures-only decoding.

We consider the erasures-only decoding of Reed-Solomon codes. One class of erasure decoders of algebraic codes can be viewed as a transformation of the systematic generator matrix, as first noticed by Berlekamp. We extend Berlekamppsilas method to Reed-Solomon codes and compare the performance of the decoder with various other Reed-Solomon erasure decoders. The developed decoder reduces the decoding time of packet erasures significantly when used in conjunction with a modified interleaver found in the literature.

In some networks, data packets either arrive without any bit errors, or one or more packets are lost, with packet switched networks as one of the most evident examples. With real-time data, the delay introduced while recovering from these losses can have a great influence on the quality of service of the application. The paper introduces a decoding algorithm that can recover from bursts of erasures by utilizing cyclic Reed-Solomon codes.

We investigate binary, number-theoretic, bit insertion/deletion correcting codes as pioneered by Levenshtein (1965, 1966, 1989). The weight spectra and Hamming distance properties of single insertion/deletion error-correcting codes are analyzed. These relationships are then extended to investigate codes that can correct multiple random insertions and deletions. From these relationships, new bounds are derived and a general construction for multiple insertion/deletion correcting codes is proposed and evaluated.

Levenshtein (1966) proposed a class of single insertion/deletion correcting codes, based on the number-theoretic construction due to Varshamov and Tenengolt's (1965). We present several interesting results on the binary structure of these codes, and their relation to constrained codes with nulls in the power spectral density function. One surprising result is that the higher order spectral null codes of Immink and Beenker (1987) are sub-codes of balanced Levenshtein codes. Other spectral null sub-codes with similar coding rates, may also be constructed. We furthermore present some coding schemes and spectral shaping markers which alleviate the fundamental restriction on Levenshtein's codes that the boundaries of each codeword should be known before insertion/deletion correction can be effected.

A maximum-likelihood algorithm for devising complete decoders for constrained codes and an algorithm for calculating the resulting error multiplication probabilities are presented. These algorithms make it possible to reduce the error multiplication when decoding the symbols of constrained codes or the symbols of various combined error correcting, constrained coding schemes after reception over channels that introduce bit errors into the symbols.>

Seven new systematic convolutional codes with good distance profiles, mostly of rates not previously investigated, have been found. New systematic convolutional codes of rates R=k/n, 4>