Indoor Off-Body Wireless Communication : Static Beamforming versus Space-Time Coding

Abstract EN

The performance of beamforming versus space-time coding using a body-worn textile antenna array is experimentally evaluated for an indoor environment, where a walking rescue worker transmits data in the 2.45 GHz ISM band, relying on a vertical textile four-antenna array integrated into his garment.

The two transmission scenarios considered are static beamforming at low-elevation angles and space-time code based transmit diversity.

Signals are received by a base station equipped with a horizontal array of four dipole antennas providing spatial receive diversity through maximum-ratio combining.

Signal-to-noise ratios, bit error rate characteristics, and signal correlation properties are assessed for both off-body transmission scenarios.

Without receiver diversity, the performance of space-time coding is generally better.

In case of fourth-order receiver diversity, beamforming is superior in line-of-sight conditions.

For non-line-of-sight propagation, the space-time codes perform better as soon as bit error rates are low enough for a reliable data link.