Upload
buinhi
View
215
Download
0
Embed Size (px)
Citation preview
WIRELESS MOBILE OR MOBILE WIRELESS?
Wireless communication systems is type of
communication system.
Dimensions of mobility:
The set of properties that distinguishes the mobile
computing system from stationary computing system.
WIRELESS & CELLULAR COMMUNICATION
Transmitting voice, data, video and other servicesdata using electromagnetic waves in open space(atmosphere).
Cellular communication:
Wireless communication using unguided media, that is,radio and microwave frequencies or satellites, has foundwidespread use in mobile phones.
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 is weak, intermittent and expensive
PORTABLE INFORMATION DEVICES
PDAs, Personal Communicators Light, small and durable to be easily carried around
dumb terminals, palmtops, wristwatch PC/Phone,
will 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 Hardware (for compression/encryption)
PORTABILITY CHARACTERISTICS
Battery power restrictions transmit/receive, disk spinning, display, CPUs, memoryconsume power
Battery lifetime will see very small increase need energy efficient hardware (CPUs, memory) andsystem software
planned disconnections - doze mode
Power consumption vs. resource utilization
PORTABILITY CHARACTERISTICS CONT.
Resource constraints Mobile computers are resource poor
Reduce program size – interpret script languages (MobileJava?)
Computation and communication load cannot be distributedequally
Small screen sizes
Asymmetry between static and mobilecomputers
MOBILITY CHARACTERISTICS
Location changes
• location management - cost to locate is added tocommunication
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
WHAT NEEDS TO BE REEXAMINED?
•Operating systems - TinyOS
•File systems - CODA
•Data-based systems – TinyDB
•Communication architecture and protocols
•Hardware and architecture
•Real-Time, multimedia, QoS
•Security
•Application requirements and design
•PDA design: Interfaces, Languages
MOBILITY CONSTRAINTS
•CPU
•Power
•Variable Bandwidth
•Delay tolerance, but unreliable
•Physical size
•Constraints on peripherals and GUIs
•Frequent Location changes
•Security
•Heterogeneity
•Expensive
•Frequent disconnections but predictable
WIRELESS TELECOMMUNICATIONS NETWORKS
WWAN communication bandwidths 1G
The first generation of wireless technology, which was analog based
2G
The second generation of digital wireless technology; accommodates voice and text
2.5G
An interim wireless technology that can accommodate voice, text, and limited graphics
WIRELESS TELECOMMUNICATIONS NETWORKS
3G
The third generation of digital wireless technology; supportsrich media such as video
3.5G
This generation was inserted into the ranks of cell phonegenerations; it refers to the packet-switched technologiesused to achieve higher transmission speeds
4G
The expected next generation of wireless technology thatwill provide faster display of multimedia
WIRELESS TELECOMMUNICATIONS NETWORKS
WWAN communication protocols Frequency Division Multiple Access (FDMA)
Time Division Multiple Access (TDMA)
Code Division Multiple Access (CDMA)
WWAN network systems Global System for Mobile Communications (GSM)
An open, nonproprietary standard for mobile voice and datacommunications
INTRODUCTION MOBILE COMPUTING
Introduction: Mobile computing is computing that allowscontinuous access to remote resources, even to small computingdevices such as laptops, palmtops and other handheld deviceslike personal digital assistants (PDAs) and digital cell phones.
Goal of Mobile Computing: “People and their machines shouldbe able to access information and communicate with each othereasily and securely, in any medium or combination of media –voice, data, image, video, or multimedia – any time, anywhere, ina timely, cost-effective way.”
MOBILE COMPUTING ISSUES
Basic issues of concern in physical mobility
Weak connectivity
Wireless connectivity
Ubiquitous computing
Mobile systems Technical issues for mobility
Security
Security infrastructure
Reliability
Naming and locating
MOBILE COMPUTING
Mobility of physical devices can be viewed at threedifferent levels:
Macro-mobility: This is mobility through a global network. While
moving in such a network, it should be possible to communicate withoutbreaking the existing access. mobile IP, which is the protocol that takes careof macro-mobility.
Micro-mobility: This is mobility of a device in one single
administrative domain of the global network. For cellular networks, this is thelowest level of mobility. Cellular IP is the protocol designed to take care ofmicro-mobility.
Ad hoc mobility: This is mobility within a mobile ad hoc network
(MANET), caused by device mobility constantly changing the networktopology.
MOBILE AGENTS
A mobile agent is a program that can movethrough a network and autonomously execute taskson behalf of the users.
Mobile agents are used to great advantage inapplications like e-commerce, software distribution,information retrieval, system administration,network management, etc.
CONTEXT-AWARE COMPUTING
A context-aware computing system is one which has user, deviceand application interfaces which enable it to remain aware ofvarious parameters like its surroundings, circumstances or actions.
The context of a mobile device represents the circumstances,situations, applications or physical environment under which it isbeing used. For example, the context is student when the device isused to download faculty lectures.
Context-aware computing leads to application-aware computingand pervasive or ubiquitous computing.
CONTEXT-AWARE COMPUTING
The five types of context-aware:
Physical context- The context can be that of the physical environment.
Computing context- Computing context is defined by interrelationships
and conditions of the network connectivity protocol in use
User context- The user context is defined as user location, user profiles,
and persons near the user.
Temporal context Temporal context defines the interrelation between
time and the occurrence of an event or action.
Structural context- It defines a sequence and structure formed by the
elements or records.
MOBILE COMPUTING DEVICES
Personal digital assistant/enterprise digital assistant
Smartphone
Tablet computer
Ultra-Mobile PC
Wearable computer
MOBILE COMPUTING LIMITATIONS
Range & Bandwidth: Mobile Internet access is generally slowerthan direct cable connections,
Security standards: When working mobile, one is dependent onpublic networks.
Power consumption: rely entirely on battery power
Transmission interferences: Weather, terrain, and the rangefrom the nearest signal point can all interfere with signalreception.
Potential health hazards: more likely to be involved in trafficaccidents.
Human interface with device: Screens and keyboards tend tobe small, which may make them hard to use.
NOMADIC, MOBILE & UBIQUITOUS
No
Network
Mobile ComputingNomadic
Computing
Wireless
Network
(B)
Fixed
Network
Wireless
Network
(A)
Fixed
Wireless
Network
Ubiquitous Computing
Ubiquitous computing (ubicomp) is a concept in software engineering and
computer science where computing is made to appear everywhere and anywhere.
WHAT IS PERVASIVE COMPUTING?
Pervasive computing is a term for the
strongly emerging trend toward:
Numerous, casually accessible, often invisible
computing devices
Frequently mobile or embedded in the
environment
Connected to an increasingly ubiquitous
network structure.
IMPRESSIVE WIRELESS INFRASTRUCTURE!
Satellite
Macro-CellMicro-Cell
Urban
In-Building
Pico-Cell
Global
Suburban
dik ©In-Room
(BlueTooth)
MOBILE APPLICATIONS
Expected to create an entire new class ofApplications
new massive markets in conjunction with the Web
Mobile Information Appliances - combining personalcomputing and consumer electronics
Applications: Vertical: vehicle dispatching, tracking, point of sale
Horizontal: mail enabled applications, filteredinformation provision, collaborative computing…
GENERAL EXAMPLES OF MOBILE COMPUTING APPLICATIONS
Vehicles
Emergencies
Traveling Salesman
Entertainment
Education
Location Dependent Services etc.