  In this paper, we first presented an analytically discussion about energy
efficiency of Medium Access Control (MAC) protocols for Wireless Body Area
Sensor Networks (WBASNs). For this purpose, different energy efficient MAC
protocols with their respective energy optimization techniques; Low Power
Listening (LPL), Scheduled Contention and Time Division Multiple Access (TDMA),
are elaborated. We also analytically compared path loss models for In-body,
On-body and Off-body communications in WBASNs. These three path loss scenarios
are simulated in MATLAB and results shown that path loss is more in In-body
communication because of less energy level to take care of tissues and organs
located inside human body. Secondly, power model for WBASNs of Carrier Sense
Multiple Access with Collision Avoidance (CSMA/CA) and beacon mode is also
presented. MATLAB simulations results shown that power of CSMA/CA mode is less
as compared to beacon mode. Finally, we suggested that hybrid mode is more
useful to achieve optimization in power consumption, which consequently results
in high energy efficiency.
