A Survey on Sensor Networks Rick Han CSCI 7143 Secure Sensor Networks Fall 2004 Introduction Overall architecture Sensor node components Sensor nets vs traditional ad hoc nets Design factors Protocol stack Physical layer Data link layer Network layer Transport layer Application layer Conclusion Differences Between Sensor Nets and Ad Hoc Nets Greater number of sensor nodes Sensor nodes are densely deployed Sensor nodes are failure prone Topology of sensor net changes frequently Broadcast not point to point Sensor node limitations power computational capabilities memory Potentially no global identification for sensor nodes Sensor Network Overview Sensor Node Components Design Factors Fault Tolerance Scalability Production Costs Hardware Constraints Sensor Network Topology Transmission Media Power Consumption Protocol Stack Protocol Stack Physical Layer Responsible for Frequency selection Carrier frequency generation Signal detection Modulation Encryption Protocol Stack Physical Layer Issues Hardware cost How do we get down to 1 node Radio Ultrawideband Zigbee IEEE 802 15 4 Protocol Stack Data Link Layer Responsible for The multiplexing of data streams Data frame detection Medium access Error control Data Link Layer Medium Access Control Goals Creation of the network infrastructure Fair and efficient sharing of of communication resources between sensor nodes Data Link Layer Medium Access Control Problems with existing MAC protocols Cellular system single hop network is impractical for sensor networks Power conservation is not stressed Security is not considered WEP for 802 11 is broken Do we care about link layer security Data Link Layer Medium Access Control Current technology Bluetooth and Mobile Ad Hoc Network MANET Both technologies are designed for smaller numbers of nodes Power consumption is still an issue Data Link Layer Medium Access Control Alternative MAC schemes MAC for sensor networks Self Organizing Medium Access Control for Sensor Networks SMACS and the Eavesdrop And Register EAR Algorithm CSMA Based Medium Access Hybrid TDMA FDMA Based Data Link Layer Medium Access Control Power Savings Basic strategy turn off radio transmitter when idle This can be ineffective due to startup costs Dynamic power management schemes may provide an answer Data Link Layer Medium Access Control Issues MAC for mobile sensor networks Power saving modes Link layer ARQ and FEC Protocol Stack Network Layer Design principles Power efficiency Data centric nodes Data aggregation is not always desirable Attribute based addressing and location awareness Minimum Energy Routing Maximum PA route Minimum energy route Minimum hop MH route Maximum minimum PA node route Directed Diffusion Route based on attributes and interests Protocol Stack Network Layer Approaches Maximum PA route Minimum energy route Minimum hop MH route Maximum minimum PA node route Protocol Stack Network Layer Schemes Data centric routing Directed Diffusion Data Aggregation Small minimum energy communication network SMECN Flooding Gossiping Sensor protocols for information via negotiation SPIN Sequential assignment routing SAR Low Energy Adaptive Clustering Hierarchy LEACH Protocol Stack Transport Layer End to end Reliability Multi hop retransmission Congestion End to end security Like SSL authentication encryption data integrity Protocol Stack Application Layer Sensor network management Database queries Time synchronization calibration Other Omissions Operating system discussion is missing TinyOS MANTIS OS Smart Card OS Security Encryption Authentication Data Integrity Availability DOS attacks Also Non repudiation and Authorization Conclusion Overall architecture Sensor node components Sensor nets vs traditional ad hoc nets Design factors Protocol stack