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