MEDiSN : SPECIAL TOPICS IN MEDICAL SECURITY AND PRIVACY

Transcription

1 MEDiSN : SPECIAL TOPICS IN MEDICAL SECURITY AND PRIVACY April 9,

2 Discussion Topics Class discussion recap Background System Requirements Architecture Tool Evaluation Simulation, Comparisons, and Pilot Security Questions Related work 2 2

3 Class Discussion Recap Real-time monitoring systems WAITER Monitors and issues alerts Uses BlueTooth On-site processing AMON 3 3

4 Background Capacity of US healthcare system Demographic trends Fatalities from lack of monitoring Disaster scenarios Inefficient tools Automated monitoring = efficiency and quality Focus on two scenarios: Mass Casualty Events Hospital Use 4 4

5 System Requirements Scalability Geographic reach Traffic direction and types QoS requirements Security Mobility Support Physiological Monitor Characteristics Presentation 5 5

6 Architecture: Conceptual Diagram 6 6

7 Architecture: Overview Physiological Monitors (PM) Multiple monitoring capabilities All UI components remotely configurable Support for motes with different sensor suites Listens to RP beacons Relay Points (RP) Routing based on Collection Tree Protocol (CTP) Dynamically adjust max retransmits and inter-packet interval (IPI) PMs do not use CTP Patient Info Packet (PIP) for downstream traffic route Periodically advertise beacons to PMs 7 7

8 Architecture: Overview (continued ) Gateway: Traffic dissemination to authenticated end-users Backend MEDiSN server N-tier architecture, using web-based services 4 Layers: data, message, business logic, and web services Authenticated clients have access and control History, configuration, user authentication, alarm monitoring and generation Light-weight server, deployable on consumer laptop Message Oriented Middleware (MOM) Uses JMS: a message queuing system to ensure transmission receipt JMS built-in security, multicast, and data buffering 8 8

9 Tool Evaluation: Simulation Parameters: network size and configuration TOSSIM (TinyOS simulator) Use ECG samples with lossless compression Node transmits 3 packets/sec: 2 ECG data packets and 1 packet with pulse oximetry, pulse rate, and control data Mushroom Topology For >90% delivery ratio, PM max is 15 per RP (after mod) Line Topology RP selection improves reception ratio Mesh Topology Reception ratio decreases on average the more PMs are supported per RP Large Networks Only critical data; 1 transmission every 30 seconds 20 RP, 500 PMs: Average Reception Ratio: above 99% Increase capacity by aggregating messages 9 9

10 Tool Evaluation: Comparisons MEDiSN vs. CodeBlue Performance of CodeBlue deteriorates with increasing number of repeaters CodeBlue has multiple levels of network priority MEDiSN treats all packets as equal; improves reliability of transmission MEDiSN outperforms CodeBlue in ARR % Two-tier (MEDiSN) vs. CTP-based PM CTP-based PM: 73.99% ARR, MEDiSN PM: 96.43% ARR Mobile vs. Static PMs Lower ARR for mobile MEDiSN PMs, but still above 90% ARR CodeBlue has 50-80% ARR for mobile PMs 10 10

11 Tool Evaluation: Pilot University of Maryland Shock Trauma Center 8 RP covering ORs and the PACU Up to 8 PMs used to track from entry including time in PACU Average reception ration 98.25% with Std.Dev. = 1.08 Johns Hopkins Hospital Emergency Room 10 days, 6 PM to midnight in ER; 46 patients Average ARR 95.43% with Std Dev = 5.41 Measurement accuracy: Sample size: 5 measurements for each of 14 participants Oxygen saturation measurements: r(14) = 0.995, p < 0.01 Pulse rate measurements r(14) = 0.98, p < 0.01 Additional Notes: Noise from other Wi-Fi devices PM battery lifespan 11 11

12 Security Questions Replay attacks (e.g. gateway requests) Periodic RP advertising: rouge RPs? PIP: route table poisoning? Data encryption? Data integrity? Node authentication? 12 12

13 Related Work AlarmNet Collecting data from sensors to monitor behavior Sophisticated query, privacy control, and data analysis Focus on longitudinal data HealthGear Similar architecture integrated with cell phones SMART project Use PDAs to collect and transmit med info 13 13

14 Questions? 14 14

15 Additional References CodeBlue AlarmNet HealthGear SMART Project 05/smart/smart.html 15 15