Transcript UPnP & DLNA
IPv6-based wireless sensor network Speaker: Yi-Lei Chang Advisor: Dr. Kai-Wei Ke 2012/05/15 1 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 2 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 3 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 • … 4 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 5 Sampled Listening 6 Sampled Listening Chirp Frame 7 Scheduling (Optimization) 8 Redefined ACK Frame 9 Listen-After-Send 10 Adaptation Layer ? 11 Node Software Architecture 12 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 13 14 IPv6 header compression Header stack 15 IPv6 header compression IPv6 header 16 Header compression HC1 encoding (1byte) Non-Compressed fields source address destination address Traffic Class and Flow Label Next Header HC2 encoding 2bit 2bit 1bit 2bit 1bit Smaller !! Find mostly used parameter, encode into less bit. 17 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) 18 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 19 Header compression Cont. • Next Header – 00: not compressed; full 8 bits are sent – 01: UDP – 10: ICMP – 11: TCP 20 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. 21 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 22 Configuration and Management IPv6 address auto-configuration • Statelessly by combining a 64-bits IEEE EUI64unique identifier with an IPv6 address prefix (e.g., link-local or subnet ID) server • Using DHCPv6 to assign an address 23 Configuration and Management IPv6 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 24 Forwarding Hop-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 25 Forwarding Quality 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 26 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… 27 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. 28 Thanks for Listening Q&A 29