Wireless sensor network

Wireless sensor network

• 1.
  2014 Real TimeCommunication In Wireless Sensor Networks (WSN) Submitted by:-
• 2.
  WHAT IS WSN?
• 3.
  Abstract:- Advances insilicon technology have led to the development of next-generation, low-cost, low-power, multifunctional, sensor devices. These devices communicate wirelessly to transmit their readings. They are called wireless sensors and compact devices that integrate communication and computation devices into a single chip. A sensor network is a collection of communicating sensing devices or nodes. A large number of sensors can be spread across a geographical area and networked in many applications that require unattended operations, hence producing a wireless sensor network (WSN). A WSN is a network that is made of hundreds or thousands of these sensor nodes which are densely deployed in an unattended environment with the capabilities of sensing, wireless communications and computations.
• 4.
  Routing Protocols forWSNs A number of routing protocols have been defined for the WSN communication. These are the following:- i)Flooding ii)Gossiping iii)Spin iv)Gear
• 5.
  1)FLOODING:- In Flooding,a node sends out the received data or the management packets to its neighbors by broadcasting, unless a maximum number of hops for that packet are reached or the destination of the packets is arrived. DEFICIENCIES:- Implosion: is the case where a duplicated data or packets are sent to the same node.  Overlap: if two sensor nodes cover an overlapping measuring region, both of them will sense/detect the same data. As a result, their neighbor nodes will receive duplicated data or messages.
• 6.
  2)GOSSIPING Gossiping protocolis an alternative to flooding mechanism. In Gossiping, nodes can forward the incoming data/packets to randomly selected neighbor node. This technique assists in energy conservation by randomization. Gossiping can solve the implosion problem.
• 7.
  3)SPIN SPIN (SensorProtocols for Information via Negotiation) is a family of adaptive protocols for WSNs.  Their design goal is to avoid the drawbacks of flooding protocols mentioned above by utilizing data negotiation and resource-adaptive algorithms
• 8.
  4)GEAR GEAR (Geographicaland Energy Aware Routing) is a recursive data dissemination protocol WSNs. It uses energy aware and geographically informed neighbor selection Heuristics to route a packet to the targeted region.
• 9.
  Different Networking Technologiesfor Wireless Sensor Networks: A. Bluetooth: IEEE 802.15.1 standard, popularly known as Bluetooth, offers moderate data rates at lower energy levels. It is ideally suited for high end WSN applications that require higher data rates with harder real time constraints. Bluetooth is used in star topology. B. ZigBee: IEEE 802.15.4 standard, popularly known as ZigBee, offers low data rates at very low energy levels. It is ideally suited for applications requiring infrequent smaller data transfers where battery life is an important issue.
• 10.
  C. UWB: Ultra wide band is a technology for transmitting information spread over a large bandwidth (>500 MHz).  Ideally suited for short distance, high speed communications with very low power budget.  As it is based on wide band technology, it can achieve very high geo-location accuracy to the sub-meter levels. D. Wi-Fi: Wi-Fi represents group of WLAN technologies defined under IEEE 802.11 standard body. Wi-Fi technologies are capable of providing very high throughput (>100 Mbps) at longer range but required very high power budget.  Also, Wi-Fi can locate end point location to the accuracy of several meters only. Because of this limitation, use of Wi-Fi is mostly restricted to devices with fixed power supply.
• 11.
  Operating systems usedin WSN A. TinyOS:  TinyOS can support concurrent programs with very low memory requirements.  The OS fits in 400 bytes.  The TinyOS component library includes network protocols, distributed services, sensor drivers, and data acquisition tools. B. Contiki OS Contiki is a lightweight open source OS written in C for WSN sensor nodes.  Contiki is a highly portable OS. A typical Contiki configuration consumes 2 kilobytes of RAM and 40 kilobytes of ROM.
• 12.
  Applications Various fieldsof applications of wireless sensor networks are: A. Area Monitoring: In area monitoring, the WSN is deployed over a region where some phenomenon is to be monitored. A military example is the use of sensors detects enemy intrusion. B. Environmental/Earth Monitoring: The term Environmental Sensor Networks, has evolved to cover many applications of WSNs to earth science research. This includes sensing volcanoes, oceans ,glaciers, forests .
• 13.
  C. Air pollutionMonitoring: Wireless sensor networks have been deployed in several cities (Stockholm, London or Brisbane) to monitor the concentration of dangerous gases for citizens. These can take advantage of the ad-hoc wireless links rather than wired installations. D. Forest fire Detection: A network of Sensor Nodes can be installed in a forest to detect when a fire has started. The nodes can be equipped with sensors to measure temperature, humidity and gases which are produced by fire in the trees or vegetation. The early detection is crucial for a successful action of the firefighters.
• 14.
  E. Landslide Detection: A landslide detection system, makes use of a wireless sensor network to detect the slight movements of soil and changes in various parameters that may occur before or during a landslide. Through the data gathered it may be possible to know the occurrence of landslides long before it actually happens. F. Water Quality Monitoring: Water quality monitoring involves analyzing water properties in dams, rivers, lakes & oceans, as well as underground water reserves. The use of many wireless distributed sensors enables the creation of a more accurate map of the water status, and allows the permanent deployment of monitoring stations in locations of difficult access.
• 15.
  G. Others: AcousticDetection Seismic Detection Military Surveillance Medical Monitoring Agriculture Sector Medical Sector