Improved BER performance in OFDM systems with frequency offset by novel pulse-shaping

An exact method for calculating the bit error rate of pulse-shaped orthogonal frequency-division multiplexing systems in the presence of frequency offset is derived. This method represents a unified way to calculate the bit error rate of different one-dimensional and two-dimensional subcarrier modulation formats, such as, binary phase shift keying (BPSK), quaternary phase shift keying (QPSK), and 16-ary quadrature amplitude modulation (16-QAM). The precise bit error rate expressions are obtained using a characteristic function method. These accurate analytical results are used to examine and compare the bit error rate performance of pulse-shaped orthogonal frequency-division multiplexing systems employing the rectangular pulse, the raised-cosine pulse, and the "better than" raised-cosine pulse when a frequency offset is present. The dependence of the bit error rate on the roll-off factor of the pulse employed for a specific system in the presence of frequency offset is also investigated. Analysis and numerical results show that employing the "better than" raised-cosine pulse rather than the raised-cosine pulse can provide better bit error rate performance in practical systems, by as much as 2-3 dB in SNR.