Explain WSN protocol stack in detail

Subject : Wireless Network

Topic : Overview of Wireless Sensor Network

Difficulty : Medium

wn(38) • 2.7k  views

The Sensor network protocol stack consists of
1) Physical layer :
a. The physical layer is responsible for frequency selection, carrier frequency generation, signal detection, modulation and data encryption.
b. The 915 MHz band has been widely suggested. “Ultra wideband (UWB) is an attractive candidate because of low transmission power, simple circuitry, use pulse position modulation, resilience to multipath.
c. Modulation depends on transceiver and hardware design constraints, which aim for simplicity, low power consumption, and low cost per unit. Binary modulation schemes are simpler to implement and deemed to be more energy efficient.

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2.Data link layer:
a) Data link layer is responsible for multiplexing data streams, data frame detection, medium access and error control. It ensures reliable Point to Point and point to multi point connections in a communication.
b) The MAC must establish communication links for data transfer in wireless multihope self - organizing sensors network. This form basic infrastructure.
c) MAC protocol must fairly and efficiently share communication resources between sensors nodes. Since there is noise and sensor nodes are mobile, MAC must be power - aware and able to minimize collision with neighbor's broadcast.
d) The main feature of MAC are periodic listen and sleep, collision and overhearing avoidance, and message passing.

3) Network Layer
a. The network layer takes care of routing the data supplied by the support layer.
b. Power efficiency is always an important consideration.

4) Transport layer
a. The Transport layer helps to maintain the flow of data if sensors network application requires it.
b. The Transmission Control protocol (TCP) need to be split into two parts. One connects sensors network to the other network like internet and the other connects the sink node to sensor nodes.

5) Application Layer:
a. Depending on Sensing tasks, different types of application software can be built and used on application layers.
b. These protocols make hardware and software of lowers layers transparent so that system administrators can edit settings.
c. These such protocols are ‘SMP'(Sensors Management protocol) ‘TADAP’ (Task assignment and data advertisement protocol), ‘SQDDP’ (Sensor query and data dissemination protocol).

6) Power, Mobility and Task Management planes.
a. When the power level of sensors node is low, it broadcast to its neighbors that it is low in power and cannot participate in routing messages. This is managed by power management plane.
b. The mobility management plane detects and registers, movement of sensors nodes. The sensors nodes can keep track of who their neighbors are.
c. The task management plane balances and schedules sensing tasks given to a specific region. Not all sensors nodes perform sensing at same time.

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