SMAC-Based WSN Protocol-Current State of the Art, Challenges, and Future Directions

Table 7

Enhanced protocols/algorithms for increased end-to-end delay/latency and packet loss of SMAC protocol.

Reference	Problem	Proposed solution/Purpose	Description	Limitations
[196]	Latency and redundant packet transmission	Express energy-efficient media access control (EX-MAC)	EX-MAC introduces a mechanism that dynamically adjusts the duty cycle based on the traffic load or message queue.	The minimization of redundant packet transmission is not clearly explained and justified. High control packet overhead.
[197]	Delay and packet loss for high-priority applications	Advanced SMAC (ADV-SMAC) protocol	# The protocol uses different queues for high priority and low priority traffic.	# Collisions may occur in sending high-priority packets in ADV-SMAC as channel sensing is excluded in the subphases.
			# It uses a contention-based approach for low priority traffic, while a TDMA approach is used for high-priority traffic.
			# Channel sensing is excluded in ADV-MAC for high-priority packets to aid in faster transmission and reduce end-to-end delay.
[112]	Delay	Designed an analytical model of SMAC	An analytical model of a multihop wireless sensor network incorporating the original SMAC protocol that constitutes a network controller based on network delay for multihop and single-hop scenarios.	# The effects of network scheduling algorithm on network stability.
		Analyzed the delay SMAC		# Analytical model on throughput and energy consumption
[198]	Delay in sending and processing high-priority data	Addition of priority bits to the beacon frame of SMAC for WVSN	# The priority bit introduced in SMAC indicates criticality and the need to process that data first in the coordinator.	# The adaptability of the proposed algorithm in mesh or ring topologies.
			# The priority bit is either 0 or 1. A data sent with a priority bit set to 0 indicates that the data is critical and must be processed first and vice versa.
[78]	Latency	Division-multiple access-media access control (MDA-SMAC)	# MDA-SMAC applies fast-binary exponential backoff algorithm to reduce data latency.	# Heterogenous scenarios
			# To reduce the collision probability of data, schedules are split into multiple microduties.
			# Adopts adaptive duty cycle and backoff algorithm.