1. 1 SAFIRENET: Next-Generation Networks for Situational Awareness Nalini Venkatasubramanian

2. 2 Situational Awareness for Firefighters Questions to be answered: Where are the firefighters? Are they doing well? Any danger? Limited infrastructure access High network deployment cost Challenges The Problem Deliver contextual data sensed by firefighters to the incident commander

3. 3 Motivation Multitude of technologies  WiFi (infrastructure, ad-hoc), WSN, UWB, mesh networks, DTN, zigbee SAFIRE Data needs  Timeliness immediate medical triage to a FF with significant CO exposure  Reliability accuracy levels needed for CO monitoring Limitations  Resource Constraints Video, imagery Transmission Power, Coverage,  Failures and Unpredictability Goal  Reliable delivery of data over unpredictable infrastructure Sensors Dead Reckoning (don’t send Irrelevant data) Multiple networks Information need DATA NEEDS

4. 4 Experiences with Existing Network Technologies… Lessons Learned: Despite multitudes of technologies, rapidly deployable, self-configuring networks that provide end-to-end & continuous connectivity are hard to create!!!

5. 5 Experiences in deploying WiFi Mesh Commercial mesh routers not good enough 5X improvement with new antenna technology Better signal coverage better building penetration Some Setup effort required Not always feasible Vulnerable to hardware failures

6. 6 SAFIRE Mote Sensor Deployment IEEE 802.15.4 (zigbee) Crossbow MIB510 Serial Gateway Polar Heart Rate Module Polar T31 Heart rate strap transmitter Proprietary EMF transmission To SAFIRE Server IMU (5 degrees of freedom) Crossbow MDA 300CA Data Acquisition board on MICAz 2.4Ghz Mote Heart Rate Inertial positioning Carbon monoxide Temperature, humidityCarboxyhaemoglobin, light

7. 7 Experiences in deploying mote sensors and Zigbee networks Calibration is essential static mobile ↑Density↑Reliability ↑Mobility↓Reliability Network convergence, gateway availability ↑Size↓Reliability Frequency matters!! Topology matters!!

8. 8 (Un) Reliability of Wi-Fi Networks Ad-hoc 1hop > Ad-hoc 2 hops > Private AP >>> Public AP No background traffic Controllable configuration Increased bandwidth share Reduced contentions/collisions Less interferences Distributed Beaconing Varying traffic load Varying traffic load Varying level of contentions and congestions Varying level of contentions and congestions Varying inter-device distance Varying inter-device distance

9. 9 Creating Reliable Networks for Onsite Communication… Goal: Enabling Robust, Timely Data Transfer by combining technologies

10. 10 Approaches Exploit multiple networks that together provide connectivity (Mobiquitous 2005, WCNC 2007, INFOCOM 2009) WiFi mesh – direct connectivity to a mesh router MANETS – hop by hop connectivity to gateway nodes Zigbee adhoc – connect to WiFi backbone through gateway node Exploit mobility when disconnected Store-and-forward networks (Delay Tolerant Networking)  mobile nodes ferry data to gateway node Combine connected network clouds and disconnected networks

11. 11 Reliable Content Delivery in Connected Networks Two aspects: Data delivery, message awareness RADCAST: Flash Broadcast in MANETS (Infocom 2009, Percom 2009) Concurrent dissemination of awareness and content  Data diffusion: based on a mix of push/pull (Pryer)  Awareness assurance: network traversal using walkers (Peddler) Problem: fast network traversal (NP-hard)  Minimizing cover time, termination time and transmission overhead Awareness Assurance Fragmentation Data Diffusion Reliable Content Dissemination Metadata Content Data { { { concurrent Walker concurrent Assures reception Pull Push concurrent Guides Retrieves missing Spreads

12. 12 Supporting Varying Reliability Needs in Connected Networks Reliability Level Reliability Needs Awareness Assurance Data Diffusion Network Size Knowledge Cost Max All reachable nodes receive the content √√ IgnoreHigh Lower- Bounded A specified number of nodes are guaranteed to receive the content √√ ExploitMedium Best-Effort As many nodes as possible receive the content, no guarantee is required √× N/ALow

13. 13 Situational Awareness in a disconnected environment Aggregate contextual data Incident Commander Board Forward bundles upon device encounters Forward bundles upon gateway encounters Periodically sensing e.g., WiFi AP fingerprints, accelerometer readings, residue battery, snapshots, audio/video recording, etc. Visualizing the task execution process spatially and temporally Easy deployment of one or several mesh routers at the edge of the area A Store-Move-and-Forward (DTN) based approach

14. 14 The Store-and-Forward Data Transfer Problem System Model Each device maintains a cache storing bundles from itself and others Devices exchange certain bundles in cache upon encounters Goals High reliability Low storage cost Low transmission cost Short latency How many copies should be generated for each bundle? Replication Which bundles should be forwarded upon device encounters, and in what order? Forwarding W h i c h b u n d l e s s h o u l d b e r e m o v e d t o a c c o m m o d a t e i n c o m i n g b u n d l e s u p o n c a c h e o v e r f l o w ? Purging Sub-Problems

15. 15 Store-and-Forward Data Transfer: Solution Overview Replication Forwarding Context Sens- ing & Collection { Purging Components Fixed Number of Distinct Copies Location- Closeness Based Aliveness-Signi- ficance Based Task Scheduling 0-1 Knapsack StrategiesModeling

16. 16 Implementation on Mobile Devices Applications Middleware DTN-Based Operating System Symbian Maemo Emergency Situ- ational Awareness RADcast Flash Broadcast

17. 17 Note: Reliable networks ≠Reliable Data Collection Sensing Errors Occur  Visibility Readings vary Occlusions etc.  Spikes in SpCO readings due to FF movement  Read errors due to misaligned sensor strip Reliability at application level is also needed needed Sensor Calibration (MMCN08)  Heart-rate, CO exposure Exploitation of Semantics, prediction Exploit application tolerance to errors