Bit by bit error rate performance of land mobile satellite system (LMSS) under fading channel using QPSK/MSK

Aspects of error performance of the land mobile satellite system (LMSS) using QPSK (quaternary phase-shift keying) and MSK (minimum shift keying) under fading channel conditions have been studied. In contrast to the sole use of average bit-error rate (BER) as a performance measure, bit-by-bit-error rates are calculated for the sequence of transmitted data under various fading conditions by computer simulation. For this purpose, various measured data from field experiments are collected and processed to yield the scaled version of fade amplitudes and phases for several data transmission cycles. Under the condition of a moving vehicle at a speed of 55 m.p.h. at 850-MHz transmission, a series of 256-b data streams at the rate of 2.4 kb/s are simulated using coherent QPSK and MSK. A total of 203.2 wavelength fade data is used to give actual fading effects. Results show that bit-by-bit error under fast varying fade can predict the exact location of error bits among the sequence of transmitted data, which cannot be done by using average BER