Table 2.

Low power MAC protocol.

Protocol	Protocol Summary
S-MAC	Saves energy by switching between active and sleep states. Maintains a common sleep schedule between neighbor nodes in low duty cycle operations. Duty cycle needs synchronizing to a specific load which can affect performance.
T-MAC	Uses adaptive duty cycle to dynamically end active part of the cycle to reduce energy wasted on idle listening. Can suffer from idle listening, reduced throughput, and increased latency.
DMAC	Utilizes data gathering trees to solve interruption problem. Adapts duty cycle depending on load.
B-MAC	Incorporates preamble sampling to reduce wakeup period. Drawback is that all nodes need to listen to the long preamble.
WiseMAC	Uses preamble sampling to mitigate overhearing and reduce power consumption. WiseMAC suffers from a long preamble and has no mechanism to adapt to changing traffic patterns. For the same delay, preamble sampling lowered power consumption by 57% when compared to 802.15.4.
X-MAC	Uses reduced length preamble, early node acknowledgement resulting in increased energy savings. Offers flexible adaptation to both bursty and periodic data sources.
NCCARQ-WSN	Network coding based. Uses less control packets than traditional cooperative ARQ protocols. Up to 50% more energy efficient without compromising QoS.
NC-PAN	Uses a hybrid cooperative network coded ARQ technique. Performance gains of up to 35% compared to B-PAN and C-PAN.