This paper presents an analytical model to evaluate the performance of the multistage multicarrier demultiplexer/demodulator (M-MCDD) in the presence of quantization noise as well as additive white Gaussian noise (AWGN) and adjacent channel interference (ACI). The analysis has been limited to halfband filter coefficient quantization. A procedure for numerical computation of the probability of bit error based on the Gram-Charlier series technique is introduced.

This paper, tutorial in nature, describes the effort of many investigators who have and still are conducting channel measurements and modeling for land mobile satellite communications. Various channel measurement results, ranging from ultrahigh frequency to Ka-band, are given. Many statistical channel models and simplified models that have been developed are referred to. Some of the models are applicable to geostationary and nongeostationary communications satellites. A statistical model developed by Loo (1985) is described in detail, as well as its extension to modeling land mobile satellite communications at Ka-band. This was accomplished by including a Gaussian probability density function to account for weather conditions. Also, practical computer-generated statistical channel models are given. These computer models should facilitate the estimation of performance of satellite communications systems.

This paper presents an analytical model to evaluate the performance of the multistage multicarrier demultiplexer/demodulator (M-MCDD) for satellite communications in the presence of additive white Gaussian noise (AWGN) and adjacent channel interference (ACI). The probability of bit error is derived. A procedure for numerical computation of the probability of bit error based on the Gauss quadrature rule (GQR) is introduced. Effects of imperfect filtering and channel separation on the performance are discussed.

This paper examines the effect of timing errors on QPSK/FDMA signals regenerated by a SAW-based group demodulator. The presence of a timing offset not only degrades the performance of that channel, but also increases the amount of its interference into other channels. Time windowing of the input to the chirp Fourier transform is shown to reduce the impact of the timing errors, but at the cost of an increased output noise variance. Measurements are presented for the bit-error rate (BER) performance of a single channel with a fixed timing offset using a surface acoustic wave (SAW) group demodulator based on the convolve-multiply-convolve (CMC) configuration with Kaiser-Bessel windowing.

This paper describes measurement results of a 20/30 GHz land mobile satellite channel at Ka-band in terms of signal envelope, signal phase and their probability distribution. The measured data represents several environmental conditions such as relatively open areas to wooded areas, lightly wooded areas and densely wooded areas. Also, the measured values show that Gaussian models can be used to approximate the signal phase characteristics under light shadowing conditions. The results described should be useful for the design of land mobile satellite communications at Ka-band.>

Derivations of the chirp Fourier transforms that can be easily implemented with surface acoustic wave (SAW) devices are described. Two configurations-the multiply-convolve-multiply (MCM) and convolve-multiply-convolve (CMC)-are treated. The derivations show that one gives the Fourier transform precisely and the other is an approximation, although a good one under most circumstances. Numerical results for the CMC are given. The results show that windowing is an effective means of reducing the sidelobe level of the output transform, but it is at the expense of widening the main lobe.>

An analytical derivation of the probability of bit error noncoherent frequency-shift keying (FSK) and coherent phase-shift keying (PSK) signals transmitted through a land-mobile satellite channel is described. The channel characteristics used in the analysis are based on a recently developed model which includes the combined effects of fading and shadowing. Analytical expressions for the probability of bit error of FSK and coherent phase-shift keying (CPSK) signals are obtained. The results show that large amounts of signal-to-noise ratio (SNR) are required to compensate for the combined effect of fading and shadowing. An analytical expression for the irreducible probability of bit error of a CPSK signal due to phase variations caused by fading and shadowing is derived. The results described should be useful in the design of land mobile satellite communication systems.>

The performance of 8-PSK and 8-DPSK trellis codes is presented for a class of fast fading, land mobile satellite communication channels. The fading model is Rician but, in addition, the line-of-sight path is subjected to a fast lognormal attenuation that represents tree shadowing. The fading parameters used in this study represent the degree of shadowing and are based on measured data. The primary application considered is for digital speech transmission and thus, bit error probabilities in the order of 10/sup -3/ are emphasized. Sensitivity of the bit error probability to amplitude fading, amplitude and phase fading, and decoding delay is presented. Performance is determined via digital computer simulation. Optimal four- and eight-state codes are determined and optimality is found to be dependent on the presence of lognormal shadowing.>