Title: CSE 535 Mobile Computing Lecture 2: An Overview of Mobile Computing: Part I Motivation and Challenge
1CSE 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
2Agenda
- Introduction to Mobile Computing
- Introduction to Wireless Sensor Networking and
Applications
3Mobile 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.
4Mobile 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.
5MC - Fundamentals
- Mobile Computing gt 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.
6Mobility and Adaptability
6
7Example 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
8Promises 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
9Mobile 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
10Vertical 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
11Horizontal 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
12Medical Example
- 911 Call
- Ambulance arrives/departs
- Closest hospital
- Access patient records
- Send vital signs
- Update patient records
- Page hospital personnel
- Order medical supplies
13Party on Friday
- Update Smart Phones calendar with guests names.
- Make a note to order food from Dinner-on-Wheels.
- Update shopping list based on the guests drinking
preferences. - Dont forget to swipe that last can of beers UPS
label. - The shopping list is always up-to-date.
14Party 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.
15Party 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-OPs PC.
- Everything will be delivered by the time
- you get home in the evening.
16Wireless Networks
17Wireless 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 199013 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)
18Wireless 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.
19Wireless 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.
20Wireless 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
23Portability 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
24Mobility 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
25What 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
-
26Wireless Sensor Networking Applications and
Challenges
- Sandeep Gupta
- Arizona State University
- Based on Slides by Prof. Loren Schwiebert, CS,
Wayne State University
27What 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
28Limitations 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
29Some 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
30Sensor-Based Visual Prostheses
Retinal Implant
Cortical Implant
31Organization 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 manage data
in this network.
32Why Wireless Sensors Now?
- Moores 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.
33Typical 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
35Historical Comparison
Consider a 40 Year Old Computer
36A 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
37Traffic 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
38Conclusions
- 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