Data Elevators Applying the Bundle Protocol in Delay Tolerant Wireless Sensor Networks Wolf-Bastian P¨ ottner, Felix B¨ usching, Georg von Zengen, Lars Wolf IEEE MASS 2012, 2012-10-09
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Motivation (a) (b) (c) (d) Vineyard Computing ZebraNet SeNDT Observation Delay Tolerance is widely used (and needed) in sensor network research Wolf-Bastian P¨ ottner | Data Elevators | 2
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Common Requirements Measurement Periodic sampling of sensor values Networking Multi-hop data delivery Store, carry and forward Disrupted links, changing topologies Delay is not important, reliability is Hardware Long lifetime → Low-power Minimal installation e ff ort → Wireless Few maintenance cycles → Robust Wolf-Bastian P¨ ottner | Data Elevators | 3
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Wireless Sensor Networks (WSNs) Wireless Sensor Networks Multi-hop wireless Battery powered Wireless Sensor Nodes INGA Based on microcontrollers IEEE 802.15.4 radios App. 16 kB RAM, app. 128 kB ROM Low-power hardware Storage (flash, SD, ...) T-Mote Sky Wolf-Bastian P¨ ottner | Data Elevators | 4
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Outline Introduction Bundle Protocol in Delay Tolerant Wireless Sensor Networks Data Elevator Application Scenario Capacity of Delay Tolerant Wireless Sensor Networks Conclusion Wolf-Bastian P¨ ottner | Data Elevators | 5
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Protocols for Wireless Sensor Networks Predominant WSN Protocols 6LoWPAN : IPv6 over low-power WPAN Contiki’s and TinyOS’ proprietary protocols → Not delay tolerant (not store, carry and forward) Store, Carry and Forward Protocols ZebraNET (non-standardized) Vineyard Computing (non-standardized) Seal-2-Seal (non-standardized) Bundle Protocol (RFC 5050) Wolf-Bastian P¨ ottner | Data Elevators | 6
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Benefits and Drawbacks of Standard Protocols Benefits Drawbacks Seamless integration Not optimized for use case Lower entry barrier Higher overhead Generic solutions Benefits of the Bundle Protocol Flexibility : Variable length header fields, extension blocks, etc. Overlay Protocol : Works on top of heterogeneous technologies Well suited : Designed for unstable links and changing topologies Q: Is the Bundle Protocol too heavy for nodes? Wolf-Bastian P¨ ottner | Data Elevators | 7
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Bundle Protocol Overhead Comparison 19 Contiki‘s RIME 802.15.4 RIME UDP / IPv6 802.15.4 IPv6 UDP 57 69 TCP / IPv6 802.15.4 IPv6 TCP UDP / 6LoWPAN 802.15.4 6LoWPAN UDP 23 TCP / 6LoWPAN 38 802.15.4 6LoWPAN TCP BP / UDPCL / 6LoWPAN 802.15.4 6LoWPAN UDP Bundle Protocol 44 BP / TCPCL / 6LoWPAN 802.15.4 6LoWPAN TCP CL Bundle Protocol 61 BP / IEEE 802.15.4 CL 31 802.15.4 Bundle Protocol Overhead [Bytes] IEEE 802.15.4 maximum frame size is 127 bytes A: Protocol overhead is higher but manageable Wolf-Bastian P¨ ottner | Data Elevators | 8
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Bundle Protocol Complexity Comparison SDNV Operations per Second Parsing of Incoming Data [us] 300 25000 Decode 280 Encode 20000 260 240 15000 220 10000 200 180 5000 6LoWPAN HC06 / UDP 160 Bundle Protocol CBHE 0 8 16 24 32 0 10 20 30 40 50 60 70 Payload Length [bytes] Integer Size [bit] Run on INGA at 8 MHz A: Computational complexity is comparable Wolf-Bastian P¨ ottner | Data Elevators | 9
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion How can we implement the Bundle Protocol on nodes? Literature Bundle Protocol as overlay protocol over 6LoWPAN Our Approach on the Nodes: µ DTN BP in IEEE 802.15.4 data frames Cross-layer, avoiding layers 3 and 4 Implementation based on Contiki OS Our Approach on the PC IEEE 802.15.4 radio attached to PC IBR-DTN software extension to handle radio Wolf-Bastian P¨ ottner | Data Elevators | 10
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Data Elevator Application Scenario Opening Question How can we get temperature readings from the rooftop into our lab? Concept Temperature Sensor #1 #2 Rooftop th Floor Node with sensor on rooftop 15 14 th Floor Elevator is data mule Elevator: 1 st 14 th Floor #3 Building A Delay tolerant network Building B Setup #5 #4 3 rd Floor 1 sensor, 3 relays, 1 sink µ DTN with RAM storage Wolf-Bastian P¨ ottner | Data Elevators | 11
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Evaluation: Temperature and Delay (Weekend) 8 24 7 21 Temperature [Degree Celsius] 6 18 Bundle Delay [h] 5 15 4 12 3 9 2 6 1 3 0 0 0 2 4 6 8 10 12 14 16 18 20 22 0 Time of Day [h] Bundle Delay Temperature Wolf-Bastian P¨ ottner | Data Elevators | 12
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Evaluation: Delay Distribution (Weekend) 100 Number of Occurrences [%] 90 80 70 60 50 40 30 20 10 0 >0-5 >10-15 >20-25 >30-35 >40-45 >50-55 >60-65 >70-75 >80-85 >90-95 >100 Bundle Delay Bins [m] Delay Distribution Accumulated Delay Distribution Wolf-Bastian P¨ ottner | Data Elevators | 13
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion DT-WSN Capacity Model Sender( Receiver( BundleRate i S Cap ,Recv S Cap , Send Storage(Capacity(( S Send , i S Recv, i Bundles(in(Storage( Channel Capacity: C i , j = Duration i · BundleRate i T i = min ( S Send , i , C i , j ) Transmitted Bundles: Storage Sender: S Send , i = min ( S Send , i − 1 − T i − 1 + N i , S Cap , Send ) S Recv , i = min ( S Recv , i − 1 + T i , S Cap , Recv ) Storage Receiver: Wolf-Bastian P¨ ottner | Data Elevators | 14
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Evaluation: Capacity Model 80 Permanently Lost Bunldes [%] 70 60 50 40 30 20 10 0 0 50 100 150 200 250 300 Sample Interval [s] Storage: 100 Bundles Storage: 500 Bundles Storage: 300 Bundles unlimited Wolf-Bastian P¨ ottner | Data Elevators | 15
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Conclusions Wolf-Bastian P¨ ottner poettner@ibr.cs.tu-bs.de http://www.ibr.cs.tu-bs.de/projects/mudtn Protocols Standard protocols are generic solutions to common problems BP is de facto standard in DTNs and should be in DT-WSNs µ DTN Bundle Protocol implementation for Contiki Overhead is comparable to 6LoWPAN Integration into existing DTNs via transparent gateway nodes Data Elevator Data is delivered with delay but without loss Wolf-Bastian P¨ ottner | Data Elevators | 16
Wolf-Bastian P¨ ottner | Data Elevators | 17
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Evaluation: Temperature and Delay (Weekday) 8 24 7 21 Temperature [Degree Celsius] 6 18 Bundle Delay [h] 5 15 4 12 3 9 2 6 1 3 0 0 0 2 4 6 8 10 12 14 16 18 20 22 0 Time of Day [h] Bundle Delay Temperature Wolf-Bastian P¨ ottner | Data Elevators | 18
Introduction Bundle Protocol Data Elevator Network Capacity Conclusion Evaluation: Delay Distribution (Weekday) 100 Number of Occurrences [%] 90 80 70 60 50 40 30 20 10 0 >0-5 >10-15 >20-25 >30-35 >40-45 >50-55 >60-65 >70-75 >80-85 >90-95 >100 Bundle Delay Bins [m] Delay Distribution Accumulated Delay Distribution Wolf-Bastian P¨ ottner | Data Elevators | 19
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