Transcript Week 12 Selected_Topics_in_Wireless

WIRELESS INTERNET
WAP Wireless Application Protocol
- WWW programming model
- Wireless Markup Language
- browser suited for mobile terminal
- lightweight communications protocol
stack
- framework for wireless telephony
applications
WMLScript
WML
Wireless Application Environment
Wireless Session Protocol
Wireless Transaction Protocol
Wireless Transport Layer Security
UDP
Wireless Datagram Protocol
IP
GSM
D-AMPS
IS-95
3G
Bluetooth
WAP is a lightweight communications
stack that is designed to minimize the
required bandwidth and maximize the
number of wireless network types that can
deliver WAP content
WML and WMLScript
Designed for mobile devices
- small displays
- navigation with a single control or
one hand
- content is scalable from lines of text
to graphic screen
WML documents are sub-divided into
small units of user interaction called cards
Users navigate by moving back and
forwards between cards
A card specifies one or more units of
interaction, a menu, a screen of text or a
text entry field
GPRS (General Packet Radio Service)
Many mobile phones and a significant
number of mobile service providers
support GPRS
This permits data to be sent at relatively
high data rates (up to 171.2 kbps) across
mobile telephone networks
Data is sent, as needed, as a packet
without the need for modem support or a
remote connection to be acquired
GPRS permits communications between a
mobile device and any other location
Therefore, mobile-Internet is a likely use
for this technology
Users can have their GPRS-enabled
devices activated (access to service,
allocation of IP address) and use the
service providers gateway to the Internet
How does it work?
Data is organised into packets that are
switched through the service provider’s
network
The link between mobile device and
network is used only when sending or
receiving data – this uses the available
radio network in an efficient manner
How does it work?
Large numbers of GPRS users can be
accommodated and share the bandwidth
of a single cell because no single device
has a dedicated channel
Many GPRS providers will be able to
support normal mobile communications
with GPRS data occurring at the same
time without having to increase cell
capacity
How does it work?
Since it is an IP-based service, any
Internet application may be ported to the
mobile device (if the device has the ability
or capacity) – WWW, Telnet, FTP, SMTP,
chat, etc
How does it work?
To gain the highest data transfer rate, a
single mobile device would have to take
over all available transmission time slots
In most situations, mobile devices will only
be able to use a smaller number of the
available timeslots
How does it work?
GPRS uses the GMSK modulation
technique
Higher data rates will only be available
when new techniques for modulation (eg 8
PSK)
How does it work?
Since packets are sent in much the same
connection-less method as IP packets,
GPRS will not be suited to high-quality
video
GPRS Applications
Chat
Text information
Still images
Moving images
WWW
Document sharing
Audio
Job dispatch
Corporate email
Internet email
Vehicle Location
Remote LAN access
File transfer
Home automation
GPRS and WAP
GPRS could carry WAP traffic and avoid
one of the limiting factors of current WAP
implementations
I-mode
NTT DoCoMo
The maximum speed for i-mode
download is 28.8 kbit/sec for top
range models, and 9.6 kbit/sec for
standard handset models for 2G imode services and on the order of
200 kbit/sec for FOMA (3G)
services.
9.6 kbit/sec is approx. 6 times
slower than a 64 kbit/sec ISDN
connection, but is sufficient for
simple imode data. Of course this
speed makes it impossible to
download live movies through
imode.
imode on FOMA (3G) is much
quicker: 384 kbit/sec download
(typically 200 kbit/sec) and 64
kbit/sec upload in best conditions
and therefore allows video-telephony.