Distributed body-worn communication system with the use of electro-textiles.

摘要

Electro-textiles made by incorporating conductive threads into fabrics are as flexible and washable as normal fabrics, and some exhibit comparable conductivity to a solid metal laminate. Wearable antennas fabricated from these electro-textiles demonstrate high antenna efficiency (78%) and moderate bandwidth (4-8% at 2.4 GHz). To explore the advantage of a body-worn wireless communication system to address multipath fading problem, distributed signal reception can be realized through multiple wearable antennas at widely spaced locations on clothing. By taking advantage of antenna diversity techniques or MIMO (Multiple Input Multiple Output) techniques, such a system can effectively mitigate "signal drop" phenomenon in most wireless communication environment. Using theoretical modeling, numerical simulation and indoor channel measurements, the performance of the above multi-antenna transceiver system was fully evaluated. It was found that the combination of pattern diversity and spatial diversity can significantly improve system gain (8-12dB diversity gain in received signal strength, about 300% increase in 10% MIMO outage capacity) compared to conventional antennas in handheld devices. To achieve a truly wearable wireless system, it is necessary to integrate the wearable antennas with other RF and baseband circuit blocks. Here, we propose a distributed multi-transceiver integration with separate RF local oscillator for each receiver chain. The proposed design is compared with traditional designs with a single shared LO reference through system modeling and simulation.