Probability of error calculation of OFDM systems with frequency offset

Orthogonal frequency-division multiplexing (OFDM) is sensitive to the carri er frequency offset (CFO), which destroys orthogonality and causes intercar rier interference (ICI). Previously, two methods were available for the ana lysis of the resultant degradation in performance. Firstly, the statistical average of the ICI could be used as a performance measure. Secondly, the b it error rate (BER) caused by CFO could be approximated by assuming the ICI to be Gaussian. However, a more precise analysis of the performance (i.e., BER or SER) degradation is desirable. In this letter, we propose a precise numerical technique for calculating the effect of the CFO on the BER or sy mbol error in an OFDM system. The subcarriers can be modulated with binary phase shift keying (BPSK), quaternary phase shift keying (QPSK), or 16-ary quadrature amplitude modulation (16-QAM), used in many OFDM applications. T he BPSK case is solved using a series due to Beaulieu. For the QPSK and 16- QAM cases, we use an infinite series expression for the error function in o rder to express the average probability of error in terms of the two-dimens ional characteristic function of the ICI.