The ultra-wide band technology, which was called Impulse Radio, was originally applied in military field. At present, more and more attention is paid to this short distance communication technology along with the FCC's agreement of its civil use. The current ultra-wide band includes two types: multi-band OFDM (MB-OFDM UWB) and direct sequence spread spectrum (DS-UWB). Because MB-OFDM UWB, which is quite mature, is not essentially different from OFDM technology, it is in dominant position in the competition. However, DS-UWB has commercial potential because of its low power and simple equipment and so on.At present, both of these two kinds of UWB are facing the same problem on how to coexistent with the existing narrow band wireless communication system. Compared with MB-OFDM UWB, the interference problem of DS-UWB is more serious, which is mainly because that the interference origin is complex and the solutions are limited. Based on DS-UWB, this article discusses DS-UWB interference origin and the frequency domain solution.
