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

networkmobile

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 master

other 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 features

licence-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

Architecture

HTML

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

ServerClient

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

GatewayWeb

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 issues

Small display - WML structures docs in

‘decks’ and ‘cards’

card represents a single unit of interaction

with user

deck is a service, represented by a

collection of cards

well suited to small displays

Limited input - WML requires minimal

keyboard functionality

Wireless device issues

cont.

Limited memory and CPU

WML is primarily text-based and requires a

low hardware overhead

Limited battery power

WAP transmissions minimised over air