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IPv6-based wireless sensor network. Speaker: Yi-Lei Chang Advisor: Dr. Kai-Wei Ke 2012/05/15. Outline. Introduction Challenges of IP over WSNs Things we can do in link layer Add an adaptation layer Make network layer more suitable for WSNs Conclusions. Introduction. WSN Limited power
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IPv6-based wireless sensor network Speaker: Yi-Lei Chang Advisor: Dr. Kai-Wei Ke 2012/05/15
Outline • Introduction • Challenges of IP over WSNs • Things we can do in link layer • Add an adaptation layer • Make network layer more suitable for WSNs • Conclusions
Introduction • WSN • Limited power • Low TX power, unstable link…etc. • Limited computing ability • Low cost lots of nodes • IP over WSN • Why need IP in WSNs • IPv6 vs. IPv4
Challenges of IP over WSNs • WSNs are... • Limited node energy • Less transmitting and computing power • High packets loss rate • Limited bandwidth • 250 Kbps for IEEE 802.15.4 • So, when IP over WSNs… • Large header overhead • 40 bytes IPv6 header • Global addressing scheme • Need auto-configuration • Other implementation challenges • 127 bytes maximum physical layer packet size (IEEE 802.15.4) work with 1280 bytes minimum MTU (IPv6) • Transport protocol • …
Things we can do in link layer • Lower energy cost • Duty-cycled link • Sampled Listening • Scheduling • Listen-After-Send • More quality link • Streaming • Redefined ACK Frame
Adaptation Layer • Transmission of IPv6 Datagram over IEEE 802.15.4 • IPv6 header compression • To reduce header overhead • Datagram fragmentation • Fragmentation header • To support the IPv6 minimum MTU • Support for layer-two forwarding • Layer3 routing, layer2 forwarding • Reduce processing power
Header compression Smaller !! Find mostly used parameter, encode into less bit.
Header compression Cont. • Source/destination address • 00: PI, II • 01: PI, IC • 10: PC, II • 11: PC, IC • PI: Prefix carried in-line • PC: Prefix compressed (link-local prefix assumed). • II: Interface identifier carried in-line • IC: Interface identifier elided (derivable from the corresponding link-layer address)
Header compression Cont. • Traffic Class and Flow Label • 0: not compressed; full 8 bits for Traffic Class and 20 bits for Flow Label are sent • 1: Traffic Class and Flow Label are zero
Header compression Cont. • Next Header • 00: not compressed; full 8 bits are sent • 01: UDP • 10: ICMP • 11: TCP
Header compression Cont. • HC2 encoding • 0: No more header compression bits • 1: HC1 encoding immediately followed by more header compression bits per HC2 encoding format.
Make network layer more suitable for WSNs • Configuration and Management • IPv6 address auto-configuration • IPv6 neighbor discovery • Forwarding • Hop-by-Hop Recovery • Quality of Service • Routing • DAG (Directed acyclic graph) • distance-vector protocol
Configuration and ManagementIPv6 address auto-configuration • Statelessly by combining a 64-bits IEEE EUI-64unique identifier with an IPv6 address prefix (e.g., link-local or subnet ID) server • Using DHCPv6 to assign an address
Configuration and ManagementIPv6 neighbor discovery • Neighbor Table • Cache Table • Reduce address resolution exchange • Address Resolution • Link-local multicast query router advertisement • Neighbor Unreachability Detection (NUD) • Neighbor solicitation (NS) • Neighbor advertisement (NA) link-layer acknowledgments • Router Discovery • Router solicitation (RS) • Router advertisement (RA) • Dynamic RA interval
ForwardingHop-by-Hop Recovery • The two most common reasons for delivery failures • Link transmission failures • Queue congestion at the receiver • Detected using hop-by-hop acknowledgments • Using flag to tell the difference • Forwarder can retransmit/reroute
ForwardingQuality of Service • Classes • ND, routing protocols, and local communication • Upward traffic towards edge routers for data collection • Downward traffic away from edge routers for configuration or control traffic • Queue reservations
Conclusions • We can use link layer mechanism to lower power consumption and improve link quality, make WSNs more powerful to carry IP. • For transmission of IPv6 Datagram (big packets) over IEEE 802.15.4(more smaller packets), add an adaptation layer • We can modify some network layer mechanism so they can be more suitable to WSNs • And more…
Reference [1]J.W. Hui and D.E. Culler, "IPv6 in Low-Power Wireless Networks,“ Proceedings of the [1]IEEE, vol. 98, no. 11, pp. 1865-1878, November 2010. [2]J.W. Hui, "An Extended Internet Architecture for Low-Power Wireless Networks [1]Design and Implementation,” PhD thesis, University of California at Berkeley, [1]Berkeley, CA, USA, 2008. [3]Joel J. P. C. Rodrigues , Paulo A. C. S. Neves "A survey on IP-based wireless sensor [1]network solutions", Int. J. Communication Systems, vol. 23, pp. 963–981, 2010. [4]G. Montenegro, N. Kushalnagar, J. Hui, and D. Culler, “Transmission of IPv6 Packets [1]Over IEEE 802.15.4 Networks,” RFC 4944 (Proposed Standard), September 2007. [5] S. Deering and R. Hinden, “Internet Protocol, Version 6 (IPv6) Specification,” RFC [1]2460 (Draft Standard), December 1998.