4 QoS Based Protocols
QoS based protocols ensure sensor nodes balance between energy consumption and pre-determined QoS metrics like delay, energy, reliability and bandwidth, before delivering data to sink node. Sensor nodes have low processing capability, low memory power and limited transmission energy in addition to energy constraints. Hence the constraints impose an important requirement on wireless sensor network QoS support mechanisms including
simplicity. Traffic flows from many sensor nodes to a small subset of sink nodes in most WSN applications. QoS mechanisms must be made for unbalanced QoS-constrained traffic.
A sensor node must route traffic according to QoS requirements as stated below:
1) Priority level based route traffic.
2) Reduce delay to relay event-based packets.
3) Ensure event alerts delivery.
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The aim of SAR algorithm is to reduce average weighted QoS metric throughout network lifetime. Another wireless sensor network QoS routing protocol that ensures soft real-time end- to-end guarantees is SPEED that ensures avoidance of congestion during network congestion.
Diff-MAC is a Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) based QoS-aware MAC protocol with differentiated services and hybrid prioritization. Diff-MAC aims at increasing the utilization of the channel with effective service differentiation mechanisms while providing fair and fast delivery of the data. Primary application field of the Diff-MAC is wireless multimedia sensor networks which commonly carries QoS-constrained heterogeneous traffic.
Equalizer-MAC (EQ-MAC) is designed to provide QoS support for cluster based single-hop sensor networks by service differentiation and uses a hybrid medium access scheme. The protocol is composed of two parts: Classifier- MAC (CMAC) and Channel Access MAC