Sandeep K. S. Gupta School of Computing and Informatics Arizona State University

1. CSE 535 – Mobile ComputingLecture 2: An Overview of Mobile Computing: Part I – Motivation and Challenges Sandeep K. S. Gupta School of Computing and Informatics Arizona State University

2. Agenda Introduction to Mobile Computing Introduction to Wireless Sensor Networking and Applications

3. Mobile Computing • The need for "information anywhere anytime" has been a driving force for the increasing growth in Web and Internet technology, wireless communication, and portable computing devices. • The field of mobile computing is the merger of these advances in computing and communication with the aim of providing seamless and ubiquitous computing environment for mobile users.   • Mobile computing techniques are essential for enabling distributed and net-centric applications which require remote and ubiquitous information access.

4. Mobile Computing Challenges • Mobile computing environments are characterized by severe resource constraints and frequent changes in operating conditions. • This has led to many new and challenging problems which span several areas of computer science such as incorporation of support for mobility in network protocols, development of efficient and adaptive resource management techniques for wireless bandwidth and battery power, predicting mobility patterns, performance modeling and simulation of mobile applications, and supporting mobile real-time multimedia applications.

5. MC - Fundamentals • Mobile Computing => Adaptive Computing and Communication • Cross-Layer approach is need for • Adaptation • Conserving resources such as energy • Mobile computing is distinct from distributed computing • Mobile computing is an essential component of Ubiquitous computing.

6. Mobility and Adaptability Application QoS (re) negotitation System Fig: Dynamic Adaptation 6

7. Example Adaptive Approaches Approach 1: Combine solutions with different optimality ranges/performance characteristics. Approach 2: Treat change in system state as a transient fault and use the techniques of designing fault-tolerant protocols Approach 3: Dynamically monitor the system state and use the solution which is suitable for the current system state. Many others - …. 7

8. Promises of Mobile Computing • 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

9. Mobile Applications • Expected to create an entire new class of Applications • new massive markets in conjunction with the Web • Mobile Information Appliances - combining personal computing and consumer electronics • Applications: • Vertical: vehicle dispatching, tracking, point of sale, information service (yellow pages), Law enforcement • Horizontal: mail enabled applications, filtered information provision, collaborative computing…

10. Vertical Applications • l 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

11. 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

12. Medical Example • 911 Call • Ambulance arrives/departs • Closest hospital • Access patient records • Send vital signs • Update patient records • Page hospital personnel • Order medical supplies

13. Party on Friday • Update Smart Phone’s calendar with guests names. • Make a note to order food from Dinner-on-Wheels. • Update shopping list based on the guests drinking preferences. • Don’t forget to swipe that last can of beer’s UPS label. • The shopping list is always up-to-date.

14. Party on Friday • AutoPC detects a near Supermarket that advertises sales. • It accesses the shopping list and your calendar on the Smart Phone. • It informs you the soda and beer are on sale, and reminds you. that your next appointment is in 1 hour. • There is enough time based on the latest traffic report.

15. Party on Friday • TGIF… • Smart Phone reminds you that you need to order food by noon. • It downloads the Dinner-on-Wheels menu from the Web on your PC with the guests’ preferences marked. • It sends the shopping list to your CO-OP’s PC. • Everything will be delivered by the time you get home in the evening.

16. Wireless Networks

17. 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; 4.4 million in 1990;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)

18. 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 • Packet Data Networks • ARDIS • RAM • Cellular Digital Packet Data (CDPD) • Private Networks • Public safety, UPS.

19. 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.

20. Wireless Characteristics • Variant Connectivity • Low bandwidth and reliability • Frequent disconnections • predictable or sudden • Asymmetric Communication • Broadcast medium • Monetarily expensive • Charges per connection or per message/packet • Connectivity may be weak, intermittent and expensive

21. Portable Information Devices • PDAs, Personal Communicators • Light, small and durable to be easily carried around • dumb terminals [InfoPad, ParcTab projects], palmtops, wristwatch PC/Phone, walkstations • run on AA+ /Ni-Cd/Li-Ion batteries • may be diskless • I/O devices: Mouse is out, Pen is in • wireless connection to information networks • either infrared or cellular phone • specialized HW (for compression/encryption)

22. 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

23. Portability Characteristics • Resource constraints • 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

24. 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

25. What Needs to be Reexamined? • Operating systems • File systems • Database systems • Programming Languages • Communication architecture and protocols • Hardware and architecture • Real-Time, multimedia, QoS • Security • Application requirements and design

26. Wireless Sensor Networking: Applications and Challenges Sandeep Gupta Arizona State University Based on Slides by Prof. Loren Schwiebert, CS, Wayne State University

27. 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. What is a Wireless Sensor Network? GPS Sensor Node

28. 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

29. Some Sample Applications • Industrial and Commercial Uses • Inventory Tracking – RFID • Automated Machinery Monitoring • Smart Home or Smart Office • Energy Conservation • Automated Lighting • Military Surveillance and Troop Support • Chemical or Biological Weapons Detection • Enemy Troop Tracking • Traffic Management and Monitoring

30. Sensor-Based Visual Prostheses Retinal Implant Cortical Implant

31. Organization into Ad Hoc Networks • Individual sensors are quite limited. • Full potential is realized only by using a large number of sensors. • Sensors are then organized into an ad hoc network. • Need efficient protocols to route and managedata in this network.

32. Why Wireless Sensors Now? • Moore’s Law is making sufficient CPU performance available with low power requirements in a small size. • Research in Materials Science has resulted in novel sensing materials for many Chemical, Biological, and Physical sensing tasks. • Transceivers for wireless devices are becoming smaller, less expensive, and less power hungry. • Power source improvements in batteries, as well as passive power sources such as solar or vibration energy, are expanding application options.

33. Typical Sensor Node Features • A sensor node has: • Sensing Material • 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 • Power Supply • Passive – Solar, Vibration • Active – Battery power, RF Inductance

34. Wireless Sensor Nodes: Examples Consider Multiple Generations of Berkeley Motes

35. Historical Comparison Consider a 40 Year Old Computer

36. A Rosy Future for Wireless Sensors? • Is the effort on wireless sensor protocols a waste of time?? • Can we just wait 10-15 years until we have sensors that are very powerful?? • NO!! Will still face: • Very limited storage • Modest power supplies

37. Traffic Management & Monitoring • Future cars could use wireless sensors to: • Handle Accidents • Handle Thefts • Sensors embedded in the roads to: • Monitor traffic flows • Provide real-time route updates

38. Conclusions • Fundamental to Mobile computing is various techniques in hardware/software to adapt to variation in resource availability – taking into account contextual information including user preferences. • Wireless sensor networking is enabling technology for pervasive/ubiquitous computing • Next Class - Continue discussion on Adaptation techniques • Read Chapter 1