Embedded Systems

Introduction: -

• computation is integrated with the control and is embedded into the physical system
• Wiring is expensive- so wireless communication between the nodes to become inevitable requirement. so wireless sensor network emerged.
• thesis Networks Consists of individual nodes That are able to interact with Their environment by sensing or controlling physical parameters, hypothesis nodes have to collaborate to Fulfill Their tasks as Ready for a single node is incapable of doing so, and They use wireless communication to enable this collaboration ,

Application examples: -

• Disaster relief Application: - wildfire detection.
• Environment Control and Biodiversity Mapping: - surveillance of the marine ground helps to find the need of offshore wind farms.
• Intelligent buildings: - Building waste vast energy by humidity ventilation and air-conditioning.
• Facility management: - Keyless entry point application where people wear badges did allow a wireless sensor network to check Which person is allowed to enter.
• Machine surveillance and preventive maintenance: - fix sensor nodes to difficult to reach area (main advantage cable free operation).
• Precision Agriculture: - Allows precise agriculture by precise irrigation and fertilizing by placing humidity or soil composition sensor.
• Medicine and healthcare: - postoperative and intensive care; Directly sensor are attached to patients; Doctor patient tracking system.
• Logistics: - embedded in the streets or roadsides can gather information about traffic

Types of application: - 

• Sources of data: - the actual nodes did sense data.
• Sinks: - nodes where the data Should be delivered to 
• Interaction pattern: - between sources and sinks show some typical patterns. Some are as follows: -1. Event Detection report once theyhave detected the occurrence of the specified event; - Event classification-> Numerous event OCCURS. 2.Periodic measurements- Periodically reporting Measured values ​​and triggered by a detected event. 3. Function approximation and Edge Detection temperature changes from one place to another and approximate mapping Should be made available at the sink. 4. Tracking source of an event can be mobile.

Examples: -

• Deployment options: - 1. Fixed deployment Machinery Maintenance Application. 2. Random deployment large number of nodes from at aircraft over a forest fire.
• Maintenance Option
• Options for Energy Supply.

Challenges of Wireless Sensor Network: -

• Characteristic Requirements Type of Service: -

1. Wireless sensor network is expected to Provide meaningful information and / or actions about a Given Task
2. service type rendered by a Conventional Communication Network is evident- it moves bits from one place to another.
3. people want answers not numbers
4. New paradigms of using a search network are required alongwith New Ways of Thinking about the service of a network.

• Quality of service: -

1. closely related to network service
2. Traditional Quality of Service include bounded delay or minimum bandwidth are irrelevant When applications are tolerant to latency.
3. Bandwidth of the Transmitted Data is very small in the first place.
4. Delay is important When actuators are to be controlled in a real time fashion by a sensor network.
5. Packet Delivery Ratio is an insufficient metric.

• Fault Tolerance: -

1. Nodes may run out off energy or Might Be damaged 
2. wireless communication between 2 nodes can be permanently interrupted
3. wireless sensor network is able to tolerate faults search.

• Lifetime: -

1. Nodes will rely on Limited Supply of Energy
2. energy efficient way of operation of the wireless sensor node is Necessary.
3. solar cells are not powerful enough to Ensure Continuous operation of the network but can Provide some recharging of batteries 
4. , Lifetime of the network therefore has direct trade-offs against quality of service.
5. precise definition depends on the application at hand
6. time until the first node fails as the network lifetime.

• Scalability: -

1. since wireless sensor network might include large nodes, the employed architectures and protocols must be able to scale to the numbers.

• Wide range of densities: -

1. Number of nodes per unit area and density can vary considerably.
2. different application has different node density
3. Density is non homogeneous network so Should Adapt to search variations.

• Programmability: -

1. nodes alongwith processing of information theywill have to react flexibility on changes in Their task.
2. Should be programmable and programming must be changeable during operation. When New Task Becomes important fixed way of processing is insufficient information.

• Maintainability: -

1. wireless sensor network changes and The System Has to Adapt.
2. network has to maintain itself
3. Interact with external maintenance mechanism to Ensure its extended operation at a required quality

Required mechanism: -

• Multihop wireless communication: -

1. long distance communication is Possible only through multihop.
2. reduce total power required due to the use of intermediate nodes as relays

• Energy efficient operation

1. Forming of hotspots is an issue

• Auto Configuration: -

1. self location 
2. tolerate failing nodes
3. integrate new nodes

• Collaboration and in Network Processing: -

1. several nodes have to collaborate to detect on event
2. EC., to find the average temperature of an area.

• Data centric: -

1. Data Transfer Among Devices dealing with Common Data
2. EC., average temperature of an area.

• Address centric: -

1. Transfer of Data between 2 specific devices equipped with one network address.

• Locality: -

1. exploit trade-offs: 1. node density. 2. Energy Efficiency.