Ultra wideband (UWB) technology is one of the promising solutions for future short-range communication which has recently been receiving increasing attention by many researchers. So far, two standards have been proposed to the IEEE 802.15.3a task group (TG3a) as high-speed physical technologies for next-generation wireless personal area networks (WPAN). These standards are based on multiband orthogonal frequency division multiplexing (MB-OFDM) UWB or direct-sequence (DS) UWB, two different technologies that will have to coexist in the near future. In this paper, we provide a performance analysis of MB-OFDM UWB communication in the presence of binary phase-shift keying time-hopping (BPSK-TH) UWB or BPSKDS UWB interfering transmissions. In the bit error rate (BER) analysis, it is considered that there are multiple UWB interferers affecting the MB-OFDM signal. A Gaussian approximation is considered for the DS-UWB and TH-UWB interferers under consideration and used in the analysis of the BER performance of a MB-OFDM UWB system. Furthermore, a waveforming technique is suggested for mitigating the effect of interference and its efficiency is illustrated in terms of BER improvement. Numerical and simulation results are provided and compared for different coexistence scenarios.