  Advances in sensor networks enable pervasive health monitoring and
patient-specific treatments that take into account the patients medical
history, current state, genetic background, and personal habits. However,
sensors are often battery power limited and vastly differ in their application
related requirements. In this paper, we address both of these problems.
Specifically, we study IEEE 802.15.6 ultra-wideband (UWB) wireless body area
networks (WBANs) that use impulse radio (IR). We formulate the joint
optimization of the payload size and number of pulses per symbol to optimize
the energy efficiency under the minimum rate constraint. The proposed
algorithm, cross-layer optimization for energy efficiency (CLOEE), enables us
to carry out a cross-layer resource allocation that addresses the rate and
reliability trade-off in the physical (PHY) layer as well as the packet size
optimization and transmission efficiency for the medium access control (MAC)
layer. Simulation results demonstrate that CLOEE can provide an order of
magnitude improvement in to static strategies.
