Desktop restrictions
Internet opens up access to millions of sites
Browser can walk down virtual high street
Massive opportunities for opening new markets through e-business
BUT Internet access through a fixed device (PC)
Mobility and access
If we can access the internet without using fixed devices; information can be provided in many
environments information can be more currente-business market could be extended
further
How do we mobilise the internet?
Bluetooth
short range, wireless link
allows ad-hoc connections between; mobile phone portable computer printer mouse headset
low power radio, 10-100m range max
2.4 GHz licence-free, frequency-hopping to avoid interference
Bluetooth
Packet Data Infrastructure
Internet
Applications: VoIP, browsing, multimedia
Addresses connectivity and convenience issues for wireless data
Cellular (GPRS,
3G)
Bluetooth
Wireless Application Protocol
addresses issues higher up the protocol stack
data links on wireless networks are lower than wired networks radio spectrum (bandwidth) limited
internet applications not designed with wireless links in mind
wireless links less reliable
Wireless Application Protocol cont.
wireless devices limited in power (batteries)
compromised features; small keypad/keyboard small display limited data storage
standard IP cannot be used with mobile devices efficiently - in some cases not possible at all (800 x 600 page on a mobile in true colour)
WAP
Packet Data Infrastructure
WAP Gateway
Internet
WAP IP
Applications: Banking, e-business, weather, news
Cellular (GPRS, SMS)
Provides translation
between WAP and IP
Bluetooth technology
access to LAN
cellular network
mobile phone
printer
laptop
laptop
mouse
2.4 GHz Licence-free
Low Tx power, low cost, battery operation
symmetric and assymetric connections
1600 frequency hops per second
* replaces proprietary cables that connect devices together *
Establishing a connection
two units within range can set up a connection (piconet)
share a channel
unit that initiates connection is masterother unit assumes role of slave
any unit can be a master or a slave
can only be one master in a piconet
Establishing a connection cont.
before connection, each unit in standby scanning frequencies every 1.28 secs keeps power demands low
after initiation, full duty cycle implemented
communicates using 2.4 GHz wavelength global compatibility
two bands available; 23 channels and 79 channels selected by software depending on geography
Bluetooth Applications
automatic synchronisation of email, calendar, telephone book, smartcard data
3-in-1 phone home cordless phone - when in proximity of home
base unit business cordless phone - use internal network conventional cellular phone
cordless headset
mobile computer conferencing
automatic tolling - quite controversial!
WAP Technology
Massive growth in Internet usage
Rapid growth in mobile voice/data services
Everyone has a mobile!
Data transfer rates limited
Key featureslicence-free standard of adapting internet technology to meet wireless constraints
Wireless Markup Language (WML) for authoring
optimised protocol stack based on HTTP and TCP
usable over a broad range of cellular data bearers
ArchitectureHTML
JavaScript
HTTP
TLS SSL
TCP/IP
UDP/IP
Wireless Application Environment (WAE)
Wireless Session Protocol (WSP)
Wireless Transaction Protocol (WTP)
Wireless Transport Layer Security (WTLS)
Wireless Diagram Protocol (WDP)
User Datagram Protocol (UDP)
Bearers: SMS, GPRS, 3G etc.
WML used here
Internet Model
Web Server
Client
Web Browser
IP Stack
CGI scripts etc.
HTML, JavaScript
The Internet
HTTP Request (URL)
HTTP Response (HTML)
Internet Protocols
WAP Model
The Internet
CGI scripts etc.
WML, JavaScript
Client WAP Gateway
Web Server
Wireless Network
Encode/decode
WAP user agents
WAP Protocol
stack
Protocol conversion
WSP Request (URL)
HTTP Request (URL)
WSP Response
(WML) HTTP Response
(WML)
WAP Protocol Internet Protocol
What’s so special about WAP?
WML is binary encoded so compact over airwaves
Extensive use of caching during sessions to minimise traffic
Handles data requests asynchronously avoids waiting for responses before handling next user
request
Designed to hold ‘long’ sessions session resumed at last point if radio link fails WTP only sends broken packets of data TCP always sends entire message again
Wireless device issuesSmall display - WML structures docs in ‘decks’ and ‘cards’card represents a single unit of interaction
with userdeck is a service, represented by a
collection of cardswell suited to small displays
Limited input - WML requires minimal keyboard functionality
Wireless device issues cont.
Limited memory and CPUWML is primarily text-based and requires a
low hardware overhead
Limited battery powerWAP transmissions minimised over air
Top Related