Abstract :
The authors address considerations of repeatability and accuracy in the measurement of BER on a 256 QAM digital radio system. When viewed in terms of state occupancies and vector transition magnitudes, pseudorandom binary sequences (PRBSs) only weakly exercise the sequences of state occupancies and transition magnitudes that statistically characterise an infinite random QAM payload. This is further aggravated if the mapping of bits into QAM symbols is static in each PRBS repetition. We have synthesised and tested a binary sequence which better imitates the statistics of an infinite random sequence in the vector symbol space. In simulation trials, the new test sequence more closely predicts the BER obtained with a much longer nonrepeating random pattern
