Presented by Viraj Anagal Kaushik Mada Presented to Dr. Mohamed Mahmoud ECE 6900 Fall 2014 Date: 09/29/2014 1
Outline Motivation • Overview • Wireless Sensor Network Components • Characteristics of Wireless Sensor Network • Individual Wireless Sensor Network Architecture • Role of Micro Processors or Embedded Systems • Wireless Sensor Network Architectures • Radio options for Wireless Sensor Network • Power considerations in Wireless Sensor Network • Applications of Wireless Sensor Network • Conclusion • 2 References •
Motivation Sensors integrated into systems. • Efficient delivery of sensed information. • Limiting the number of sensors that may be deployed. • Fewer catastrophic failures. • Conservation of natural resources. • Improved manufacturing productivity, • Improved emergency response • Enhanced homeland security • 3
OUTLINE Motivation • Overview • Wireless Sensor Network Components • Characteristics of Wireless Sensor Network • Individual Wireless Sensor Network Architecture • Role of Micro Processors or Embedded Systems • Wireless Sensor Network Architectures • Radio options for Wireless Sensor Network • Power considerations in Wireless Sensor Network • Applications of Wireless Sensor Network • Conclusion • 4 References •
Overview A Wireless Sensor Network (WSN) consists of base stations and a number of wireless sensors (nodes). Data is collected at the wireless sensor node, compressed, and transmitted to the gateway directly. If required, uses other wireless sensor nodes to forward data to the gateway. 5
OUTLINE Motivation • Overview • Wireless Sensor Network Components • Characteristics of Wireless Sensor Network • Individual Wireless Sensor Network Architecture • Role of Micro Processors or Embedded Systems • Wireless Sensor Network Architectures • Radio options for Wireless Sensor Network • Power considerations in Wireless Sensor Network • Applications of Wireless Sensor Network • Conclusion • 6 References •
Wireless Sensor Network Components 7
OUTLINE Motivation • Overview • Wireless Sensor Network Components • Characteristics of Wireless Sensor Network • Individual Wireless Sensor Network Architecture • Role of Micro Processors or Embedded Systems • Wireless Sensor Network Architectures • Radio options for Wireless Sensor Network • Power considerations in Wireless Sensor Network • Applications of Wireless Sensor Network • Conclusion • 8 References •
Characteristics Of WSN Requirements: small size, large number, tether ‐ less, and low cost. • The ideal wireless sensor is networked and scaleable, consumes very • little power. Is smart and software programmable, capable of fast data acquisition, • reliable and accurate over the long term. Costs little to purchase and install, and requires no real maintenance. • Examples of low data rate sensors include temperature, humidity, and • peak strain captured passively. Examples of high data rate sensors include strain, acceleration, and • vibration. Constrained by Energy, computation, and communication • Small size implies small battery • Low cost & energy implies low power CPU, radio with minimum • bandwidth and range Ad ‐ hoc deployment implies no maintenance or battery replacement • To increase network lifetime, no raw data is transmitted • 9
OUTLINE Motivation • Overview • Wireless Sensor Network Components • Characteristics of Wireless Sensor Network • Individual Wireless Sensor Network Architecture • Role of Micro Processors or Embedded Systems • Wireless Sensor Network Architectures • Radio options for Wireless Sensor Network • Power considerations in Wireless Sensor Network • Applications of Wireless Sensor Network • Conclusion • 10 References •
Individual Wireless Sensor Node Architecture Sensor event ‐ driven data collection model minimizes the power consumed by the • system. Depending on the sensors to be deployed, the signal conditioning block can be re ‐ • programmed or replaced. The radio link may be swapped out as required for a given applications wireless range • requirement and the need for bidirectional communications. The use of flash memory allows the remote nodes to acquire data on command from a • base station, or by an event sensed by one or more inputs to the node. 11
OUTLINE Motivation • Overview • Wireless Sensor Network Components • Characteristics of Wireless Sensor Network • Individual Wireless Sensor Network Architecture • Role of Micro Processors or Embedded Systems • Wireless Sensor Network Architectures • Radio options for Wireless Sensor Network • Power considerations in Wireless Sensor Network • Applications of Wireless Sensor Network • Conclusion • 12 References •
Role of Microprocessors or Embedded Systems The Microcontroller Unit (MCU) is the primary choice for in ‐ node • processing Power consumption is the key metric in MCU selection. • The MCU should be able to sleep whenever possible, like the radio. • Memory requirements depend on the application • ATmega128L and MSP430 are popular choices • Managing data collection from the sensors • Performing power management functions • Interfacing the sensor data to the physical radio layer • Managing the radio network protocol. • The hardware should be designed to allow the microprocessor to • judiciously control power to the radio, sensor, and sensor signal conditioner. 13
Radio Commercially ‐ available chips • Available bands: 433 and 916MHz, 2.4GHz ISM bands • Typical transmit power: 0dBm. • Power Control Sensitivity: as low as ‐ 110dBm • Narrowband (FSK) or Spread Spectrum communication. DS ‐ SS (e.g., • ZigBee) or FH ‐ SS (e.g., Bluetooth) Relatively low rates (<100 kbps) save power. • Power Supply AA batteries power the vast majority of existing platforms. They dominate the node • size. Alkaline batteries offer a high energy density at a cheap price. The discharge curve is • far from flat, though. Lithium coin cells are more compact and boast a flat discharge curve. • Rechargeable batteries: Who does the recharging? • Solar cells are an option for some applications. • Fuel cells may be an alternative in the future. • Energy scavenging techniques are a hot research topic (mechanical, thermodynamical, • electromagnetic). 14
OUTLINE Motivation • Overview • Wireless Sensor Network Components • Characteristics of Wireless Sensor Network • Individual Wireless Sensor Network Architecture • Role of Micro Processors or Embedded Systems • Wireless Sensor Network Architectures • Radio options for Wireless Sensor Network • Power considerations in Wireless Sensor Network • Applications of Wireless Sensor Network • Conclusion • 15 References •
Wireless Sensor Networks Architecture Star Network (Single Point ‐ to ‐ Multipoint) • Mesh Network • Hybrid Star – Mesh Network • 16
Wireless Sensor Networks Architecture Star Network (Single Point ‐ to ‐ Multipoint) A single base station can send and/or receive a message to a number of remote nodes. • The remote nodes can only send or receive a message from the single basestation, • they are not permitted to send messages to each other. Advantages • Is in its simplicity and the ability to keep the remote node’s power consumption • to a minimum. low latency communications between the remote node and the basestation. • Disadvantages • Basestation must be within radio transmission range of all the individual nodes • Not as robust as other networks due to its dependency on a single node to • 17 manage the network.
Wireless Sensor Networks Architecture Cont. Mesh Network Any node in the network to transmit to any other node in the network that is within its • radio transmission range. This allows for what is known as multihop communications • It can use an intermediate node to forward the message to the desired node. • Advantages • Redundancy and Scalability • The range of the network is not necessarily limited by the range in between single • nodes. Disadvantages • Power consumption is higher for multihop communications. • Limited battery life. • The time to deliver the message also increases due to increase in nodes in path. 18 •
Wireless Sensor Networks Architecture Cont. Hybrid Star – Mesh Network The lowest power sensor nodes are not enabled with the ability to forward messages. • This allows for minimal power consumption to be maintained. • Other nodes on the network are enabled with multihop capability, allowing them to • forward messages from the low power nodes to other nodes on the network. Generally, the nodes with the multihop capability are higher power, and if possible, are • often plugged into the electrical mains line. This topology is implemented by the coming mesh networking standard known as • ZigBee. 19
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