## 2 Related Work
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Protocol** & **Standard** & **Access Scheme** & **Theme** & **Focused QoS** \\ \hline \multirow{4}{*}{T-MAC [25]} & \multirow{4}{*}{IEEE 802.15.4} & \multirow{4}{*}{Hybrid} & T-MAC allows the nodes to turn on the radios & \multirow{4}{*}{R, E} \\  & & & on pre-synchronized timings and turn off in case of no & \\  & & & communication. T-MAC adjusts radio-on interval with & \\  & & & the traffic rate, so there is no fix radio-on interval & \\  & & & which makes T-MAC adaptive. It provides reliable & \\  & & & and energy efficient communication. & \\ \hline \multirow{4}{*}{S-MAC [14]} & \multirow{4}{*}{IEEE 802.15.4} & \multirow{4}{*}{Hybrid} & S-MAC is considered as a predecessor of T-MAC and & \multirow{4}{*}{D, E} \\  & & & provides fixed radio-on intervals and solves idle & \\  & & & listening problem. The coordinator assigns those & \\  & & & wakeup intervals, after transmission the nodes go to & \\  & & & sleeping mode. S-MAC gives low latency as due to & \\  & & & synchronization there are less chances of collisions. & \\ \hline \multirow{4}{*}{B-MAC [22]} & \multirow{4}{*}{IEEE 802.15.4} & \multirow{4}{*}{Hybrid} & B-MAC [26] presents three bandwidth management schemes i.e., burst, periodic and adjusts bandwidth. & \multirow{4}{*}{E, D} \\  & & & B-MAC works in the environment where there is & \\  & & & synchronization among sensor nodes and gateway & \\  & & & nodes. Therefore, nodes only wakeup for transmit or & \\  & & & receive the data. It uses Contention Free Period (CFP) to & \\  & & & save energy. It also uses CSMA/CA in Intention & \\  & & & Access Period (CAP) for some specific scenario & \\  & & & where network joining conditions are flexible. & \\ \hline \multirow{2}{*}{X-MAC [15]} & \multirow{2}{*}{IEEE 802.15.4} & \multirow{2}{*}{Hybrid} & X-MAC improves the B-MAC by making small preamble & \multirow{2}{*}{E, D} \\  & & & burst with destination address instead of long preamble. & \\ \hline \multirow{2}{*}{PNP-MAC [26]} & \multirow{2}{*}{IEEE 802.15.4} & \multirow{2}{*}{Hybrid} & Preemptive slot allocation and non-preemptive & \multirow{2}{*}{D, E} \\  & & & transmission MAC support medical applications & \\  & & & through superframe adjustments. & \\ \hline \multirow{2}{*}{VMAC [29]} & \multirow{2}{*}{IEEE 802.15.4} & \multirow{2}{*}{Hybrid} & VMAC provides adaptive resource scheduling using & \multirow{2}{*}{R, T} \\  & & & asymmetrical architecture which provides reliability & \\  & & & with bandwidth guarantee. & \\ \hline EMAC [27] & IEEE 802.15.4 & Hybrid & EMAC integrates relay nodes & \\  & & & to save the energy resources. & \\ \hline YNU-MAC [19] & IEEE 802.15.6 & CSMA/CA & Uses SIFS, DIFS and backoff in contention window and & \multirow{2}{*}{T, R} \\  & & & provide efficient channel utilization with high data rates. & \\ \hline \multirow{2}{*}{NICT MAC [10]} & \multirow{2}{*}{IEEE 802.15.6} & \multirow{2}{*}{TDMA} & Suitable for star topology and is usable in beacon & \multirow{2}{*}{E, S} \\  & & & and beaconless mode and introduce the concept & \\  & & & of group BAN superframe for scalability. & \\ \hline WiseMAC [34] & IEEE 802.15.6 & TDMA & It is applicable for both for star and mesh & \\  & & & topology and provides scalability. & \\ \hline \multirow{2}{*}{IMEC [28]} & \multirow{2}{*}{IEEE 802.15.6} & \multirow{2}{*}{Hybrid} & It uses enhanced slotted aloha by & \multirow{2}{*}{E} \\  & & & incorporating dual duty cycling and & \\  & & & provides flexibility and power efficiency. & \\ \hline \multirow{2}{*}{C-MAC [23]} & \multirow{2}{*}{IEEE 802.15.6} & \multirow{2}{*}{TDMA} & C-MAC is made for mobile clusters for & \multirow{2}{*}{C} \\  & & & WBASNs and control the interference & \\  & & & and collisions due to mobile nodes. & \\ \hline MEB- MAC [18] & IEEE 802.15.6 & \multirow{2}{*}{Hybrid} & MEB-MAC protocol inserts a listening window in CFP & \multirow{2}{*}{D} \\  & & & and provides less delay to the medical applications. & \\ \hline MFS-MAC [16] & IEEE 802.15.6 & \multirow{2}{*}{Hybrid} & Improved MAC protocol for WBASN to satisfy the & \multirow{2}{*}{E} \\  & & & energy consumption of implantable devices. & \\ \hline \multirow{2}{*}{DT-SCS [35]} & \multirow{2}{*}{IEEE 802.15.4e} & \multirow{2}{*}{Hybrid} & Performs decentralized time-synchronized & \multirow{2}{*}{T, E} \\  & & & channel swapping (DT-SCS) and reduces certain & \\  & & & convergence and network utilization problems. & \\ \hline \multirow{2}{*}{QL-MAC [36]} & \multirow{2}{*}{IEEE 802.15.4} & \multirow{2}{*}{Hybrid} & A machine learning based approach that & \multirow{2}{*}{T,E} \\  & & & produces significant improvements in & \\  & & & terms of network lifetime and throughput. & \\ \hline \hline \end{tabular}
\end{table}