Slide 46 -
The principles and concepts behind Smartphones Today’s talk: The triple nature of a smartphone Embedded and pervasive computing platform
run general-purpose programs
have conventional interface
Persistent and ubiquitous device – must be pervasive
Mobile Computing platform
Operates on the go
Adapts to available resources
Wireless sensor platform
It contains an array of sensors
Context-aware Embedded Computing Platform Wireless Sensor
Platform Mobile Computing
Platform Mobile (and adaptive) Computing Mobile computing?
Mobility of communications devices
Difference between mobile computing and mobile communications?
Ex. “Italian restaurant” through search engine.
Ex. Video streaming over the Internet
Limitations of mobile computing devices: energy, screen, …
Security or privacy
Middleware layer What is Mobile Computing The vision of mobile computing
Roam seamlessly with your computing devices while continuing to perform computing and communication tasks uninterrupted.
Global information services at any time from any location
Mobile users as integrated consumers and producers of data and information
Ubiquitous computing where mobile computers become an integral part of daily activities
The ability of a system to hide some characteristics of its underlying implementation from users
Location transparency: name transparency, user mobility
Mobile computing: mobility transparency Adaptability – The key to Mobile Computing Constraints of mobile computing environments
Mobile computers can be expected to be more resource-poor than their static counterparts: e.g., battery
Mobile computers are less secure and reliable.
Mobile connectivity can be highly variable in terms of its performance (bandwidth and latency) and reliability.
Application-transparent (the system is fully responsible for adaptation)
Laissez-faire (the system provides no support at all)
E.g., bandwidth, battery
Fig 1.2 What can be adapted?
The functionality and the data
How to adapt?
Client-server (CS) model
A server with soft or hard state about the clients
Coda File servers (Saty 1996a)
A few trusted servers act as the permanent safe haven of the data.
A large number of un-trusted clients can efficiently and securely access the data.
Good performance is achieved by using techniques such as caching and prefetching.
Security of data is ensured by employing end-to-end authentication and encrypted transmissions. Mechanisms for Adaptation Impact of mobility on the CS model: a resource-poor mobile client = thin clients
Fidelity: the degree to which a copy of data presented for use at the client matches the reference copy at the server.
Video data – frame rate and image quality
Spatial data – minimum feature size
Telemetry data – sampling rate and timeliness
Agility: the speed and accuracy with which an adaptive application detects and responds to changes in its computing environments, e.g., change in resource availability. Detection of changes
software sensors, e.g. for connectivity, monitor the quality of link
State-based approach, i.e. chose an operating state according what is sensed.
Employment of compensating mechanisms
Profiling, Caching, Prefetching
TCP & congestion control
Detection: Use of timers/timeouts. States: governed by window size
Coda (continued data availability) distributed file system
Hoarding (prefetching), Emulating (local reads and writes), Write-disconnected (mixed mode), Reintegration (incorporate backlog of changes to original remote files) Incorporating adaptations in applications Mobility Characteristics Location changes
location management - cost to locate is added to communication
Heterogeneity in services
bandwidth restrictions and variability
Dynamic replication of data
data and services follow users
Querying data - location-based responses
Security and authentication
System configuration is no longer static Adaptivity to mobility: What is affected? Operating systems
Communication architecture and protocols
Hardware and architecture
Real-Time, multimedia, QoS
Application requirements and design
Context-Aware Computing Context awareness: adaptability Context awareness
Adapt to available resources (connectivity, nearby devices
Adapt to the situation (mode, location, time, event)
Intention awareness (?)
Adapt to what the user wants to do Defining Context Dictionary definition: “the interrelated conditions in which something exists or occurs”
One definition [Schilit]:
Computing context: connectivity, communication cost, bandwidth, nearby resources (printers, displays, PCs)…
User context: user profile, location, nearby people, social situation, activity, mood …
Physical context: temperature, lighting, noise, traffic conditions …
Time context (time of day, week, month, year…)
Context history can also be useful Context (cont’d) Is all this information necessary?
“Context is the set of environmental states and settings that either determines an application’s behavior or in which an application event occurs and is interesting to the user”
Active context: influences the behavior of the application
Location in a call forwarding application
Passive context: context that is relevant but not critical
Active map application: display location name and other people in the room
Is all this information measurable?
Temperature? Location? People around? Social situation? Mood? Context-Aware computing How to take advantage of this context information?
Schilit’s classification of CA applications:
Proximate selection: user interface where nearby objects are emphasized/made easier to choose
Automatic contextual reconfiguration: a process of adding/removing components or changing relationships between components based on context change
Contextual information and commands: produce different results according to the context in which they are issued
Context-triggered actions: rules to specify how the system should adapt
Are these fundamental/inclusive? Location-Based Services Requirements
Geocoder (convert street addresses to latitude / longitude), Reverse geocoder
Address Helper (many addresses inaccurate or incomplete)
Points of Interest data e.g. pubs, restaurants, cinemas
Business Directory (doctors, plumbers etc by location)
Connection to Telco or satellite Issues
Content providers – Telcos jealously guarding own domain
Proprietary software e.g. Windows Live
Price of map data varies widely, very expensive in some countries e.g. Australia
Integration into customer’s web sites (API’s)
Cognitive Routing – routing / directions using terminology relevant to user (e.g. resident c/f tourist) Mobile social networking meets location based services
Mobile friend tracking & directory services
Proprietary internal messaging connectable to any messaging service
Friends become closer than ever because you know where they are
Location from GPS+map service LBS + Social Networking: BuddyFinder App Mobile Computing Applications Applications:
Vertical: vehicle dispatching, tracking, point of sale, information service (yellow pages), Law enforcement
Horizontal: mail enabled applications, filtered information provision, collaborative computing… Excercise Name a smartphone app and identify its adaptability and context awareness
Handling variable resources
Handling variable context
Location, time Wireless Communications and Networks Wireless Networks Wireless Networks Cellular - GSM (Europe+), TDMA & CDMA (US)
FM: 1.2-9.6 Kbps; Digital: 9.6-14.4 Kbps (ISDN-like services)
Cellular Subscribers in the United States:
90,000 in 1984 (<0.1%); 4.4 million in 1990 (2.1%); 13 million in 1994; 120 million in 2000; 187.6 million by 2004 (Cahner In-State Group Report).
Handheld computer market will grow to $1.77 billion by 2002
Public Packet Radio - Proprietary
19.2 Kbps (raw), 9.6 Kbps (effective)
Private and Share Mobile Radio
Paging Networks – typically one-way communication
low receiving power consumption
Satellites – wide-area coverage (GEOS, MEOS, LEOS)
LEOS: 2.4 Kbps (uplink), 4.8Kbps (downlink) Wireless Networks (Cont.) Wireless Local Area Networks
IEEE 802.11 Wireless LAN Standard based systems, e.g., Lucent WaveLan.
Radio or Infrared frequencies: 1.2 Kbps-15 Mbps
Wireless Metropolitan Area Networks
IEEE 802.16 Worldwide Interoperability for Microwave Access (WiMAX)
Microwave frequencies (2.5-66GHz), broadband (<70MBps), metropolitan coverage (1 to 30 miles)
Packet Data Networks
Cellular Digital Packet Data (CDPD)
Public safety, UPS. Wireless Local Area Network Data services: IP packets
Coverage Area: Offices, buildings, campuses
Roaming: Within deployed systems
Internet access: via LAN.
Type of services: Data at near LAN speed. Variant Connectivity
Low bandwidth and reliability
predictable or sudden
Charges per connection or per message/packet Connectivity may be weak, intermittent and expensive Portability Characteristics Battery power restrictions
transmit/receive, disk spinning, display, CPUs, memory consume power
Battery lifetime will see very small increase
need energy efficient hardware (CPUs, memory) and system software
planned disconnections - doze mode
Power consumption vs. resource utilization
Mobile computers are resource poor
Reduce program size – interpret script languages (Mobile Java?)
Computation and communication load cannot be distributed equally
Small screen sizes
Asymmetry between static and mobile computers Based on Slides by Prof. Loren Schwiebert, CS, Wayne State University
Wireless Sensor Networking: Applications and Challenges What is a Wireless Sensor Network? Wireless Sensor Node = Sensor + Actuator + ADC + Microprocessor + Powering Unit + Communication Unit (RF Transceiver)
An ad hoc network of self-powered and self-configuring sensor nodes for collectively sensing environmental data and performing data aggregation and actuation functions reliably, efficiently, and accurately. GPS Sensor Node Limitations of Wireless Sensors Wireless sensor nodes have many limitations:
Modest processing power – 8 MHz
Very little storage – a few hundred kilobits
Short communication range – consumes a lot of power
Small form factor – several mm3
Minimal energy – constrains protocols
Batteries have a finite lifetime
Passive devices provide little energy Some Sample Applications Industrial and Commercial Uses
Inventory Tracking – RFID
Automated Machinery Monitoring
Smart Home or Smart Office
Military Surveillance and Troop Support
Chemical or Biological Weapons Detection
Enemy Troop Tracking
Traffic Management and Monitoring Retinal Implant Cortical Implant Sensor-Based Visual Prostheses Typical Sensor Node Features A sensor node has:
Physical – Magnetic, Light, Sound
Chemical – CO, Chemical Weapons
Biological – Bacteria, Viruses, Proteins
Integrated Circuitry (VLSI)
A-to-D converter from sensor to circuitry
Packaging for environmental safety
Passive – Solar, Vibration
Active – Battery power, RF Inductance Traffic Management & Monitoring Future cars could use wireless sensors to:
Handle Thefts Sensors embedded in the roads to:
Monitor traffic flows
Provide real-time route updates Ayushman*: A Pervasive Healthcare System Project @ IMPACT Lab, Arizona State University
To provide a dependable, non-intrusive, secure, real-time automated health monitoring.
Should be scalable and flexible enough to be used in diverse scenarios from home based monitoring to disaster relief, with minimal customization. Vision * Sanskrit for long life To provide a realistic environment (test-bed) for testing communication
protocols and systems for medical applications. K. Venkatasubramanian, G. Deng, T. Mukherjee, J. Quintero, V Annamalai and S. K. S. Gupta,
"Ayushman: A Wireless Sensor Network Based Health Monitoring Infrastructure and
Testbed", In Proc. of IEEE DCOSS June 2005 Environmental
Sensors (Temperature etc) Medical Sensors
(EKG, BP) controlled
By Mica2 motes Body Based
Intelligence Home/Ward Based
Intelligence External Gateway Central Server Medical Facility Based
Professional Internet Stargate
Gateway Ayushman: Current Setup Internet Environmental
Light) Blood Pressure Oximeter ZigBee 802.11 Remote Clients Central Server Base
Station Body Area Network RS232 Properties
Hardware and software based architecture
Real-time, continuous data collection
Query support (past, current data)
Remote monitoring capability through the Internet
Simple alarm generation database Bluetooth Enabling Technologies TOS v.1.x-2.0 Ad-hoc
Networking Mica2 TelosB Imote2 Mica2Dot Iris MicaZ Commercially available sensor boards Open source OS with support for ad hoc networking + Phone to WSN Interface Design Principles:
To minimize the changes to the existing WSN architecture (required to maintain backward compatibility with previous apps.)
To leverage COTS hardware and existing software solutions (to minimize the development time).
Issues to address:
Phone to sensors interface
Data handling on the cell phone Monitoring and Control Software Context Generation Physiological
Heart Rate) Environmental
(Home, Gym, Office,
Sensor Network Knowledge Context
Processor Medical Context
Is an aggregate of 4 base contexts.
Each physiological event has to be characterized by all 4 base contexts for accurate understanding of patient’s
A contextual template can be created for specific physiological events for future reference.
How to determine the aggregate medical context from the four base contexts?
How to create a contextual template for a patient? Aggregate
Context Base Context Security in Pervasive Healthcare Context
Patient data is transmitted wirelessly by low capability sensors
Patient data is therefore easy to eavesdrop on
Security schemes utilized may not be strong enough for cryptanalysis
Patient data is stored in electronic format and is available through the Internet
Makes it easy to access from around the world and easy to copy
Data can be moved across administrative boundaries easily bypassing legal issues.
Electronic health records store more and more sensitive information such as psych reports and HIV status
Preserving patient’s privacy is a legal requirement (HIPAA)
Wireless connectivity is always on
No clear understanding of:
Security policies for medical environment
Devices are heterogeneous with limited capabilities
Traditional schemes too expensive for long term usage Security Related Issues New Attacks
Fake emergency warnings.
Legitimate emergency warnings prevented from being reported in times.
Unnecessary communication by malicious entity with sensors can cause:
Battery power depletion
Tissue heating Technology
Efficient cryptographic primitives
Cheaper encryption, hash functions
Better sensor hardware design
Cheap, tamper-resistant sensor hardware
Better communication protocol design
Better techniques for controlling access to patient EHR Legislation
Health Information Privacy and Accountability Act (HIPAA)
Passed in 1995
Provides necessary privacy protection for health data
Developed in response to public concern over abuse of privacy in health information
Establishes categories of health information which may be used or disclosed Requirements
Integrity - Ensure that information is accurate, complete, and has not been altered in any way.
Confidentiality - Ensure that information is only disclosed to those who are authorized to see it.
Authentication – Ensure correctness of claimed identity.
Authorization – Ensure permissions granted for actions performed by entity. Energy Efficiency Need
Sensors have very small battery source.
Sensors need to be active for long time durations.
For implantable sensors, it is not possible to replace battery at short intervals.
Battery power not increasing at same rate as processing power.
Small size (hence less energy) of the batteries in sensors. Solutions Solar Energy Better Battery Vibration Body Thermal Power End of class Follow-up question in on-line discussion
Next class (January 27th)
Topic: Pervasive Location-based services
Review material: Chapters 2 & 4 of the textbook Extra Slides Mobile Computing Applications: Vertical Applications Serve a narrow, niche application domain
– Services dispatch (taxi, fire, police, trucking)
– Sales tracking (point of sale, market trends)
– Mail and package tracking (courier, postal)
Relatively easy to implement due to
restrictions and assumptions
– homogeneous MUs
– limited numbers of users
Mobile Computing Applications: Horizontal Applications Broad, domain-independent applications serving a mass-market
– Electronic Mail and News
– Yellow Pages Directory Services
– Multimedia Merchant Catalogs
– Digital Libraries
– Location-based Information Filtering
Driving force of mobile computing research