Search

This paper addresses the problem of selecting the optimum training sequence for channel estimation in communication systems over time-dispersive channels. By processing in the frequency domain, a new explicit form of search criterion is found, the gain loss factor (GLF), which minimizes the variance of the estimation error and is easy to compute. Theoretical upper and lower bounds on the GLF are derived. An efficient directed search strategy and optimal sequences up to length 42 are given. These sequences are optimal only for frequency domain estimation, not for time domain estimation.

This paper uses some computational results to show that the peak envelope power (PEP) of orthogonal frequency-division multiplex (OFDM) waveforms can be reduced very substantially by coding to select only those messages with low peak factor as valid codewords in the scheme. It is shown that the asymptotic limit of the PEP is between two and three, and that only four bits of redundancy are necessary to limit the PEP to within 10% of this optimum value as the number of carriers becomes large. Index Terms - Coding, orthogonal frequency-division multiplex, peak envelope power.

In a South London general practice a substantial proportion of patients in some age groups (35 and 45 yr) had tried alternative treatment. Satisfaction with the outcome was limited. The use of alternatives was associated with higher general practice consultation rates, especially among women. Qualitative interviews with users suggested that rapid cures for chronic conditions were rarely expected; rather, an alternative explanation for health problems was sought and a greater sense of autonomy in dealing with them. Negative attitudes towards modern medicine arose from perceptions of excessive technological intervention and iatrogenic disorders arising from long term drug treatment.

The new definitions together with a complete characterization of all eban numbers are presented. The eban numbers are those that do not contain the letter e in its name.

This article, appearing in a special issue on 'King Lear' and theater, analyzes William Shakespeare's play 'The Tempest' and focuses on techniques of dramatic characterization. The interrelationships between bodily portrayal and textual content are discussed.

The author argues that melodrama should not be considered unintellectual or lacking in form and seriousness, and supports this view with a close analysis of several melodramas. Topics addressed include the place of language and spectacle in melodrama, the use of pantomime, and how a lack of speech is used to elicit an emotional response from the audience.