Wireless Sensor Networks

By. P. Victer Paul

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A sensor is a electronic device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument.

A wireless sensor network (WSN) consists of spatially distributed autonomous sensors to cooperatively monitor physical or environmental conditions,

such as  temperature, sound, vibration, pressure, motion or pollutants.

Flexible.

Implementation cost is cheaper than wired network.

Ideal for the non-reachable places such as across river, or mountain or boarder areas.

Ideal for temporary network setups. 

Lower speed compared to wired network. (of course!)

Less secure because hacker's laptop can act as Access Point.

More complex to configure than wired network.

Affected by surrounding. E.g: walls (blocking), microwave oven (interference), far distance (attenuation)

Limited Energy,

Limited Memory,

Limited Computing Power,

Limited Communication Bandwidth,

Limited Communication Range

Node Deployment Node Capabilities Network Topology Scalability Energy Consumption Data Delivery Model Data Aggregation QoS

Node Deployment: affects the performance of the routing protocol.

Node Capabilities: relaying, sensing and aggregation

Network Topology: affects latency, robustness, and capacity.

Scalability: Sensor network routing protocols should be scalable enough to respond to events in the environment.

Energy Consumption: computations and transmitting

Data Delivery Model: continuous, event-driven, query-driven, periodic, or a hybrid.

Data Aggregation: duplicate suppression, minima, maxima, and average.

QoS (quality of services): should support the life time, the data reliable, and location-awareness.

Microcontroller performs tasks, processes data and controls the functionality of other components in the sensor node.

A microcontroller is often the best choice for  embedded systems because of its flexibility to connect to other devices, ease of programming, and low power consumption.

Sensor nodes make use of ISM band which gives free radio, spectrum allocation and global availability.

The function both of transmitter and receiver are combined into a single device know as transceivers are used in sensor nodes

Flash memories are used due to its cost and storage capacity.

 Two categories of memory based on the purpose of storage ◦ a) User memory used for storing application related or

personal data. ◦ b) Program memory used for programming the device.

For the Sensing, Communication and Data Processing.

Dynamic Power Management (DPM) and Dynamic Voltage Scaling (DVS)

Spoofed, altered, or replayed routing information. Selective forwarding Sinkhole attack The Sybil attack Wormhole attack HELLO flood attack

Spoofed, altered, or replayed routing information: Affects: routing loops, attract or repel network traffic, extend

or shorten source routes, generate false error messages, partition the network, increase end-to-end latency, etc.

Selective forwarding: In a selective forwarding attack, malicious nodes may refuse to forward certain messages and simply drop them, ensuring that they are not propagated any further.

Sinkhole attacks: Sinkhole attacks can enable many other attacks(e.g. selective forwarding).

The Sybil attack: In a Sybil attack, a single node presents multiple identities to other nodes in the network.

Wormhole attack: Wormhole attacks commonly involve two distant malicious nodes colluding to understate their distance from each other by relaying packets along an out-of-bound channel available only to the attacker.

HELLO flood attack: Laptop-class attacker broadcasting routing or other information with large enough transmission power could convince every node in the network that the adversary is its neighbor.

Homeland security Multisensory Data Fusion Nondestructive Evaluation and Remote Sensing Integrated System Health Management (ISHM) Commercial Development Agriculture Mines Industrial

 Standards and specifications

  Hardware

Software

Simulators

ISA100 (industrial control applications).

Wireless HART (designed for Industrial applications like Process Monitoring and Control).

IETF RPL(Routing Protocol for Low power and Lossy Networks). IETF 6LoWPAN IEC 62591(industrial communication networks)

ZigBee  networking specification for transmission of packets over IEEE 802.15.4 is intended for uses such as embedded sensing, medical data collection, consumer devices like television remote controls, and home automation.

EnOceanis the originator of patented energy-harvesting wireless sensor technology.

The main challenge is to produce low cost and tiny sensor nodes. With respect to these objectives, current sensor nodes are mainly prototypes. Miniaturization and low cost are understood to follow from recent and future progress in the fields of MEMS and NEMS.

TOSSIM,   J-Sim 

Atarraya.

An extensive list of simulation tools for Wireless Sensor Networks can be found at the CRUISE WSN Simulation Tool Knowledgebase.

Tanq