Wireless Communication Transmission Research Articles

Performance of Nondiversity Receivers for Spread Spectrum in Indoor Wireless Communications

In this work we have considered direct-sequence spread-spectrum transmission for indoor wireless communications. We have modeled the indoor communications medium, which is a multipath fading channel, by a discrete set of Rayleigh faded paths. We have proposed new analytical techniques to evaluate the probability of error for the receiver terminals studied in this work. Numerical results reveal that, for the nondiversity receivers considered here, Rayleigh fading is very hostile to this form of modulation/multipleaccess technique. The results also indicate that either some form of operation to prevent Rayleigh fading or diversity operation to counteract Rayleigh fading is required.

Adaptive transform coding of speech using vector quantization

AbstractA digital wireless communication and speech packet transmission are two types of communication in which medium‐band (4.8‐9.6 kbps) speech coding for transmission and storage is essential. This paper investigates the minimization of waveform distortion using a waveform coding which is affected little by ambient noise.An adaptive transform coding of speech using vector quantization (ATC‐VQ) is proposed. Two methods are introduced to utilize vector quantization in a frequency domain.