Data rate for DS-UWB communication systems in wireless personal area networks

A direct sequence ultrawideband system has been investigated to examine the upper bound on the achievable throughput of such a system in a practical multipath environment of a typical office. A time domain 3-D ray tracing model is adopted to consider the specific communication environment. The channel impulse responses from a reference transmitter and/or interfering users are predicted from the deterministic 3-D model with time domain expressions. The simulations are carried out for a pragmatic antenna pattern e.g. the discone antennas rather than the ideal isotropic antenna considered in many previous simulations. Pulse distortions caused by antennas and scatterers along propagation paths, the inter-symbol interference and multi-user interference are taken into account. The source signals are carefully selected to ensure the radiated signal meet the requirements of the FCC emission mask. In a single-user system, the throughput is determined to converge to 725 Mbps at a range of 5 meters between transmitter and receiver, with a minimum pulse transmission period of 1.38 ns. In multi-user systems, the data rate per user reduces exponentially with the number of users to retain an acceptable bit-error performance. It is concluded that in a typical personal office space with 10 active users, the upper bound on the data rate per user can reduce to 34 Mbps with an average bit error rate of 10^-4.