Lan F.Akyildiz,Weilian Su, Erdal Cayirci,and Yogesh sankarasubramaniam IEEE Communications Magazine 2002 Speaker:earl A Survey on Sensor Networks

Outline Introduction Communication architecture Protocol stack Conclusion

Sensor Networks … low-cost, rapid deployment, self-organizing, and fault tolerance Application areas: heath, military, and home Large number of sensor nodes that are densely deployed Nodes use their processing abilities to locally carry out simple computations and transmit the required and partially processed data Introduction

Application areas - heath

Compress data to reduce storage and communication bandwidth! Application areas - military

Inactive Sensor Application areas

Active Sensor Application areas

Ad hoc networks are not suitable for the sensor networks because of their unique features and application requirement The sensor network may have a much larger number of nodes Transmission power and radio range Topology changes Mobility rate Power conservation Introduction

Internet and Satellite Sink Task manager node User Sensor nodes Sensor field A B C D E Communication Architecture

Fault Tolerance the ability to sustain sensor network functionalities without any interruption due to sensor node failures Scalability the density of sensor nodes can range from few sensor nodes to few hundred sensor nodes in a region Production Costs the cost of sensor node should be much less than US$1 in order for the sensor network to be feasible Environment can work in different environments Design Factors

Power Unit Power generator Location finding systemMobilizer Transceiver SensorADC Sensing Unit Processing Unit Processor Storage Design Factors Hardware Constraints

Sensor Network Topology Predeployment and deployment phase Post-deployment phase Redeployment of additional nodes phase Transmission Media links between nodes can be formed by radio, infrared, or optical media Power Consumption battery lifetime design of power-aware protocols and algorithms Design Factors

Protocol Stack Application layer Transport layer Network layer Data link layer Physical layer Power management plane Mobility management plane Task management plane

Multiplexing of data streams Data frame detection Medium access and error control Ensures reliable point-to-point and point- to-multipoint connections in a communication network The Data Link Layer

Goals share communication resources between sensor nodes fairly and efficiently The Data Link Layer - Medium Access Control

MAC protocolPower conservation SMACS and EAR[13]Random wakeup during setup and turning off while idle Hybrid TDMA/FDMA[8]Hardware-based approach for system energy minimization CSMA-based[9]Constant listening time for energy efficiency The Data Link Layer -Some of the proposed MAC protocols

Power saving modes of operation Turning the transceiver off during idling may not always be efficient due to energy spent in turning it back on each time Error control Two modes of error control:  Forward Error Correction(FEC) decoding complexities  Automatic Repeat Request (ARQ) additional retransmission energy cost and overhead The Data Link Layer

The Data Link Layer -Research issues MAC for mobile sensor networks Determination of lower bounds on the energy required for sensor network self-organization Error control coding schemes Power-saving modes of operation

Task: energy efficient routes Sink A (PA=2) B (PA=2) C (PA=2) T D (PA=3) E (PA=1) F (PA=4) α 1 =1 α α 10 =2 α α α α α α α 5 =2 3 =2 4 =2 2 =1 6 =2 7 =1 8 =2 9 =2 Route 1: Sink-A-B-T, total PA=4, total α = 3 Route 2: Sink-A-B-C-T, total PA=6, total α = 6 Route 3: Sink-D-T, total PA=3, total α = 4 Route 4: Sink-E-F-T, total PA=5, total α = 6 Approaches: Minimum PA route: route 4 Minimum Energy (ME) route: route 1 Minimum hop (MH) route: route 3 Maximum minimum PA node route: route 3 PA: available power α:: energy required Network Layer

Data Aggregation, data fusion A B C D E F G Sink Network Layer

Flooding each node receiving a data or management packet repeats it by broadcasting Deficiencies  Implosion  Overlap Gossiping send the incoming packets to a randomly selected neighbor Deficiency: takes a long time to propagate the message to all sensor nodes Network Layer - Routing techniques

Sensor Protocols for Information via Negotiation (SPIN) Step 1 ADV Step 2 REQ Step 3 DATA Step 4 ADV REQ Step 5Step 6 DATA Network Layer

Sequential Assignment Routing (SAR) Creates multiple trees where the root of each tree is a one-hop neighbor from the sink Low-Energy Adaptive Clustering Hierarchy (LEACH) Forms clusters to minimize energy dissipation Directed diffusion Sets up gradients for data to flow from source to sink during interest dissemination Network Layer

LEACH and Directed diffusion LEACH Directed diffusion

Conclusion Sensor network is a new Research issue