## 4 Energy Efficient Protocols, and Scheduling in WBSNs
### Energy Efficient Protocols in MAC Layer
\begin{table}
\begin{tabular}{c c c c c} \hline
**PROTOCOOLS** & **MAC OPERATION** & **ADVANTAGES** & **DISADVANTAGES** & **COMMENTS** \\ \hline \multirow{6}{*}{BodyMAC [44]} & \multirow{6}{*}{TDMA} & Flexible bandwidth allocation. Nodes and & \multirow{6}{*}{Unsuitable scheme for collision avoidance.} & Star topology and \\  & & gateway synchronized & & \\  & & allowing sleep mode. Good & & \\  & & for periodic data sensing & & \\  & & and event reporting. & & \\ \hline \multirow{6}{*}{MEDMAC [45]} & \multirow{6}{*}{ADAPTIVE TDMA} & Maximize energy efficiency through dynamical & \multirow{6}{*}{Low performance for high data rate applications.} & Star topology. TDMA synchronization. \\  & & adjustments for QoS & & \\  & & requirements. Good for low rate (Class 0) and medium & & \\  & & data rate (Class 1) medical & & \\  & & applications. & & \\ \hline \multirow{6}{*}{NEW IMPROVED LEACH [43]} & \multirow{6}{*}{TDMA/ Clustering} & Distributed protocol, control information from the base station is not required. MD node is introduced to allow sleep mode periodically.} & \multirow{6}{*}{Extra overhead for dynamic clustering.} & A clustering topology is used. Efficiency is increased 50\% than LEACH protocol. \\ \hline \multirow{6}{*}{POWER EFFICIENT MAC [46]} & \multirow{6}{*}{TDMA/superframe enabled} & Better performance in energy saving and delay compared to WiseMAC, ZigBee, B-MAC, and XL-MAC protocols Wakeup mechanism enabled to reduce energy consumption with sleep mode. & \multirow{6}{*}{No existing evaluation for security and QoS parameters. Nodes must wake up to receive the beacon.} & Network lifetime is increased thanks to an overhead reduction. Two priorities for traffic: periodic or normal, and random or emergency. \\ \hline \multirow{6}{*}{HIGHLY HELIABLE ENERGY-SAVING MAC [20]} & \multirow{6}{*}{Distributed Queuing Body Area Network.} & QoS parameters are considered. A Cross-layer fuzzy logic scheduler is used. & Star topology for BSN under two different realistic hospital \\  & & fuzzy logic scheduler is used. & & \\  & & fuzzy logic scheduler is used. & & \\  & & by using Energy-aware & Nodes must wake up to & \\  & & radio-activation policies, & receive the beacon. & \\  & & prosors transmit at lowest & & \\  & & possible level specified & & \\  & & in 802.15.4. & & \\ \hline \multirow{6}{*}{EQ-MAC [47]} & \multirow{6}{*}{Hybrid TDMA and CSMA schemes} & Efficient node’s battery usage and support for QoS based on the service differentiation concept (data & Data redundancy in the sensor network. Low & Sensor Simulator is used for large-scale networks. EQ-MAC \\  & & & differentiation concept (data & rates. High latency without & outperforms Q-MAC \\  & & prioritization traffic levels). & traffic prioritization. & and S-MAC protocols. \\ \hline \end{tabular}
\end{table} 
Table 3: Comparison between different energy efficient MAC protocols. introduces a Guard Band (GB) for each time slot to allow the sleeping mode of nodes between one or several beacon periods. The GB is calculated by an Adaptive Guard Band Algorithm (AGBA) so that each node has a dedicated time slot to avoid collisions. To compare MEDMAC with IEEE 802.15.4 MAC protocol, three types of data classes are mentioned:  
* Class 0: Low grade data (e.g., respiratory, pulse and temperature sensor). * Class 1: Medium grade data (e.g., ECG, EEG, blood pressure, Sp02). * Class 2: High grade data (video, medical imaging, EMG, capsule endoscope). Results indicate that MEDMAC can work more efficiently for low and medium data rate than IEEE 802.15.4 MAC. IEEE 802.15.4 has higher power consumption due to overhead; at medium grade data, MEDMAC performance is stable up to 24 nodes, while IEEE 802.15.4 is unstable for more than 13 nodes. Also, MEDMAC consumes less than 10% of the energy that IEEE 802.15.4 MAC protocol does. An energy efficient MAC protocol using wake up radio is presented in [46]. Two basic priorities for traffic are defined: periodic or normal, and random traffic or emergency.