BER Performance of Stepped θ-QAM

M-ary stepped θ-QAM for M = 2
^2l
, m ≥ 3, was reported recently. Symbol error rate (SER) and optimum angle θ in terms of minimum SER were analyzed and it was confirmed that optimum angle converges to 60°. However bit error rate (BER) of stepped θ-QAM has not been analyzed yet. In this paper, we present a bit-to-symbol mapping by using layer labeling algorithm which is computationally efficient method and analyze the BER performance of M-ary stepped θ-QAM in additive white Gaussian noise (AWGN) channel. We then validate theoretical error performance and show that stepped θ-QAM offers better BER performance than conventional QAMs by Monte Carlo simulations.