In implant body area networks (BANs), an ultra-wideband (UWB) technology is a promising candidate to accomuplish high data rate. However, due to its frequency, the UWB signals suffer from large attenuation in the implant communication link. This fact suggests the difficulty on achieving reliable communication. For achieving reliable communication, it is well known that a spatial diversity technique is efficient. In this study, the authors pay attention to the fact that it is possible to further miniaturise the UWB antenna due to its very high frequency. Then, the authors aim to develop a transmit polarisation diversity antenna for implant UWB communications, and apply the developed transmit diversity system to a UWB-impulse radio (UWB-IR) scheme and a multiband-orthogonal frequency division multiplexing (MB-OFDM) scheme, respectively. For evaluating the proposed system, the authors first analyse the propagation characteristics in the implant UWB channel, using the finite difference time domain numerical analysis technique. Then, the authors evaluate and discuss the communication performances of the both modulation schemes for the transmit polarisation diversity. As a result, at a communication distance of 7 cm, the throughputs have accomplished to 300 Mbps for the MB-OFDM scheme and 30 Mbps for UWB-IR scheme, respectively.
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