  In this paper, we study the performance of two cross-layer optimized dynamic
routing techniques for radio interference mitigation across multiple coexisting
wireless body area networks (BANs), based on real-life measurements. At the
network layer, the best route is selected according to channel state
information from the physical layer, associated with low duty cycle TDMA at the
MAC layer. The routing techniques (i.e., shortest path routing (SPR), and novel
cooperative multi-path routing (CMR) incorporating 3-branch selection
combining) perform real-time and reliable data transfer across BANs operating
near the 2.4 GHz ISM band. An open-access experimental data set of 'everyday'
mixed-activities is used for analyzing the proposed cross-layer optimization.
We show that CMR gains up to 14 dB improvement with 8.3% TDMA duty cycle, and
even 10 dB improvement with 0.2% TDMA duty cycle over SPR, at 10% outage
probability at a realistic signal-to-interference-plus-noise ratio (SINR).
Acceptable packet delivery ratios (PDR) and spectral efficiencies are obtained
from SPR and CMR with reasonably sensitive receivers across a range of TDMA low
duty cycles, with up to 9 dB improvement of CMR over SPR at 90% PDR. The
distribution fits for received SINR through routing are also derived and
validated with theoretical analysis.
