Wireless networks - Lecture 37: Transport protocols/security in WSN

Wireless networks - Lecture 37: Transport protocols/security in WSN. The main topics covered in this chapter include: transport protocols for WSN; TCP/UDP for WSN; protocols; security threats in WSN; TinySec; motivations of link layer security; TinySec design goals; semantic secure encryption in TinySec;...

Wireless Networks Lecture 37 Transport Protocols/Security in WSN Part IV Dr Ghalib A Shah Outlines  Transport Protocols for WSN  TCP/UDP for WSN  Protocols ► PSFQ ► ESRT ► CODA      Security Threats in WSN TinySec Motivations of Link Layer security TinySec Design goals Semantic Secure Encryption in TinySec Last Lecture  Routing Challenges and Design Issues ► Deployment, Routing method, heterogeneity, fault tolerance, power, mobility etc  Routing Protocols ► ► ► ► ► ► ► ► SPIN Directed Diffusion ACQUIRE LEACH TEEN/APTEEN GAF GEAR SPEED Reliable Transport Protocols for Wireless Sensor Networks Sink-to-Node(s) Transport    Pump Slow Fetch Quickly (PSFQ) Reliable Multi-Segment Transport (RMST) Garuda Nodes-to-Sink Transport   Event-to-Sink Reliable Transport (ESRT) End-to-End Reliable Event Transfer in WSNs Congestion Control   Congestion Detection and Avoidance (CODA) Mitigating Congestion in WSNs Why not TCP or its variants for WSN?  Higher overheads for short data transmissions  Flow and congestion control cause unfair bandwidth for farther nodes  Throughput degrades under wireless due to higher packet losses  End-to-end congestion needs longer time to mitigate congestion, causing more congestion to occur  End-to-end reliability consumes more energy and bandwidth than hop-by-hop  Packet-based reliability, which is not required for eventdriven applications Why not UDP?  Lower over overheads but ► No congestion control ► No flow control ► No reliability Pump Slowly, Fetch Quickly (PSFQ)  Nodes broadcast fragments, in-sequence to next hop, which stores and forwards If a node detects gap it broadcasts a NACK Hop-by-hop store and forward Applic atio n Reprogramming or re­tasking of sensor networks Fe ature s NACK, In sequence caching, Loss due to transmission  drops not congestion, Hop­by­hop error recovery Go als Operate under high error rates, minimum support from  underlying layers, low latency, minimize no of  transmissions for lost detection and recovery De s c riptio n Pump, Fetch, Report Msgs C.Y Wan, A.T Campbell, and L Krishnamurthy, “PSFQ: A Reliable Transport Protocol for Wireless Sensor Networks,” WSNA'02, Atlanta, Georgia, USA, September 28, 2002 PSFQ Operations Pump Ope ratio n   User Node broadcasts a packet to its neighbors every Tmin Decrements TTL and schedules a transmission ► ► Tmin