Post on 09-Jan-2016
description
MOBILE COMPUTING & MOBILE COMMUNICATION SYSTEMS
What is Mobile Computing? Wireless Communication Systems Mobile Communication Systems Architecture
Key Technologies of Mobile Computing Applications
WHY MOBILE COMPUTING ?
People are mobile
WHY MOBILE COMPUTING ?
Devices are mobile
WHAT IS MOBILITY?
A person who moves between different geographical locations between different networks between different communication devices between different applications
WHAT IS MOBILITY?
Mobile computing is about both physical and logical computing entities that move Physical entities
computers change locations Logical entities
a running user application or a mobile agent migrating over internet
BUZZWORDS – NOMADIC-MOBILE-UBIQUITOUS
Nomadic computing refers to limited migration migration is within a building at a pedestrian speed
interleaved pattern of user relocation and indoor connections
users carrying laptop with wireless access are engaged in nomadic computing
BUZZWORDS – NOMADIC-MOBILE-UBIQUITOUS
Mobile computing requires wireless h/w to support outdoor mobility and handoff from one h/w to the next at a pedestrian or vehicular speed
traveler in car using laptop / smart phone / mobile device connected with a GSM/WCDMA/HSPA phone engaged in mobile computing
Ubiquitous computing or pervasive computing refers to access to computer network all the time at any location by any person
can not be realized unless mobile computing matures
RELATIONSHIP – NOMADIC-MOBILE-UBIQUITOUS
My Dream of Futurehttp://www.youtu.be/ujk1cprLpD8
Social Web of Thingshttp://www.youtu.be/i5AuzQXBsG4
Imagine Everything was Linkedhttp://youtu.be/igsJxXMssGA http://www.youtu.be/__pkZ4-kNvYhttp://www.youtu.be/tvpRJrQ8Z2c
HETEROGENEOUS WIRELESS COMMUNICATION WORLD
DAB: Digital Audio BroadcastVHE: Virtual Home Environment
DVB-T: Digital Video Broadcast TerrestrialUMTS: Universal Mobile Telecommunication System
HETEROGENEOUS WIRELESS COMMUNICATION WORLD
Heterogeneous wireless networks consists of Cellular networks WLAN networks other access technologies
Users should be able to access various services from various networks with varying properties in terms of data rates, SNR, latency, coverage, price etc.
Multiple devices or multi-mode devices may be used to access various services which add to the complexity of the system
Mobile communication in such a scenario requires automatic rearrangement of communication and services
These adaptive services need to be centered around the user since multiple networks and operators may be present
NATURAL EVOLUTION OF COMPUTING
Freedom from Collocation
More Flexible Resource Usage
CHALLENGE
Physical location of mobile is not the network address (address migration) existing applications send packets to a fixed network address
need to support dynamically changing “local” addresses as mobile device moves through network
how do we route the message to a mobile host
Internet communityMobile IP deals with location of mobile host
Mobile IP assumes connectionless, packet switching scenario
Mobile IP specification: home environment tracks mobile device’s current location through registration procedure
Cellular communitybased on location management of cellular phone users
it deals with connection oriented communication (motivated by issues in call-setup in telephony)
trade-off between searching and informinginforming is a responsibility of the mobile unit when it migrates
extreme situationsmobile unit never informs - works for units receiving few messages and for units which don't move during receiving
mobile unit always informs - works well for units receiving messages frequently
CHALLENGE
Ad hoc routing algorithms Ad hoc networks arise in rapid deployment scenariosemergency disaster managementmilitary operation in remote sitesbusiness meeting venues without infrastructure support
Routing algorithmsAODV, DSR, DSDV, TORA, FSR, LAR, ABR, etc.
CHALLENGE Harsh communications environment
lower bandwidth / higher latencygood enough for video conferencing?
variable bandwidth: applications adaptation to changing quality of connectivityhigh bandwidth, low latencyhigh bandwidth, high latencylow bandwidth, high latency
higher error rates: congestion, interference, etc.
more frequent disconnection performance depends on density of nearby users but frequency reuse architecture helps
network failure is common
CHALLENGE
Two modes of information dissemination Publish
data is filtered by client, server provides directory information for assisting the filtering
advantageshot spots can be broadcast frequently - which saves energy at client, avoid congestion.
Provide on demand
CHALLENGE
Services providing issues Interoperability and adaptability to h/w environments ranging from high to low bandwidths and wireless communication links
Energy efficient data access Support for mobility and disconnection
CHALLENGE
Handoff management a mobile host moves from one cell to another while being connected
undesirable featurescall droppingping-pong handoffs
vertical handoff among heterogeneous networks
HETEROGENEOUS WIRELESS COMMUNICATION WORLD
DAB: Digital Audio BroadcastVHE: Virtual Home Environment
DVB-T: Digital Video Broadcast TerrestrialUMTS: Universal Mobile Telecommunication System
CHALLENGE
Security concerns Authentication is critical
normal network point of attachment is a wall tap
wireless access makes network attachment too easy
Exposure to over-the-air wiretappingany transmitter can also be a receiver!some wireless networks provide secure airlinks (e.g., CDPD)
made more difficult by spread spectrum technologies
Mobile agent security