This paper investigates the performance of the space-time-frequency coded (STFC) multiband orthogonal frequency division multiplexing ultra-wideband (MBOFDM UWB) system over wireless body area network (WBAN) channels, using the Alamouti code. Different MIMO configurations and different modulations are used for comparison. The effect of body directions is also assessed by simulation in this paper. Simulation results show that the proposed STFC MB-OFDM UWB system provides a significantly better BER performance, compared to the conventional MB-OFDM system, even from a reasonably low Eb/No range. The simulations also confirm that the body direction affects the system performance significantly due to the availability of line-of-sight (LOS) or partial LOS paths. Overall, the STFC MB-OFDM UWB system can provide an energy efficient and robust, high data rate transmission for WBAN applications.