  We present the performance of MIMO for in vivo environments, using ANSYS HFSS
and their complete human body model, to determine the maximum data rates that
can be achieved using an IEEE 802.11n system. Due to the lossy nature of the in
vivo medium, achieving high data rates with reliable performance will be a
challenge, especially since the in vivo antenna performance is strongly
affected by near field coupling to the lossy medium and the signals levels will
be limited by specified specific absorption rate (SAR) levels. We analyzed the
bit error rate (BER) of a MIMO system with one pair of antennas placed in vivo
and the second pair placed inside and outside the body at various distances
from the in vivo antennas. The results were compared to SISO simulations and
showed that by using MIMO in vivo, significant performance gain can be
achieved, and at least two times the data rate can be supported with SAR
limited transmit power levels, making it possible to achieve target data rates
in the 100 Mbps.
