Wireless Communication - Personal Cityu Edu Hk

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21 Νοε 2013 (πριν από 4 χρόνια και 1 μήνα)

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Wireless Communication

Understand the trend of wireless communication

Understand WAP protocol, PCS, GSM and
CDMA

Understand the power of combining mobile
communication with the Internet called Mobile
Internet.


Terminologies


3G, "3rd generation",, generally applied to
wideband mobile services and applications.


3GPP, Third Generation Partnership Project,,
set up to speedup the development of open
globally
-
accepted technical specifications for
G.


Bluetooth, A global initiative by Ericsson,,
IBM,, Intel,, Nokia and Toshiba to set a
standard for cable
-
free connectivity between
mobile hones,, mobile PCs,, hand held
computers and other peripherals.

Terminology


CDMA, Code Division Multiple Access. The code
division technology was originally developed for
military use over 30 years ago. CDMA is a
multiple access technique,, which uses code
sequences as traffic channels within common
radio channels
-

used for CDMA One (IS
-
95)

air interface.


EDGE, Enhanced Data rates for GSM Evolution.
EDGE has been developed for those networks
that didn't but a UMTS license and while it
promises only about a third of the bandwidth

Terminology


GPRS, General Packet Radio Systems. GPRS is
hailed as the 2.5 for mobile phones and will be with
us from the beginning of 2001. GPRS will give you a
permanent connection at about 50 kbps or so to your

mobile phone.


GSM, Short for Global system for Mobile
Communications,, it is the mobile phone platform
used in Europe,, Hong Kong and much of the rest of
the world. However,, it is not mainstream in the USA.
Dual band phones are capable of operating on other
bandwidths aboard.

Terminology


iMode, Japanese network NTT DoCoMo has
had a great deal of success with iMode,, with the
main advantage over WAP being that it is
packet
-
switched network.


UMTS, Universal Mobile Telephony System.
This is almost universally subscribed to standard
for the third generation and is generally based
on W
-
CDMA (Wideband Code Division Multiple
Access) telephony students. It promises a
permanent internet connection of at least
384kbps and up to about 2mbps,,


Terminology


WAP, Wireless Application Protocol.
The development of WAP is being
driven by the WAP Forum,, initially
founded by Motorola


Digital Television



The television signals that we are using are
analogous, not digital. Digital TV not just the
change of signal transmission format, but also the
interactivity between the TV set and audience.


Cost and Benefit


there are cheaper ways to get a picture as good as
digital as within the 100hz screen technology
costing around US900+,


That is similar to the real Dolby Digital sound that
we hear in DVD machines.



Components


To receive ONDigital Terrestrial TV (BBC
-
ITV), there is a need to install a set top box
connected to the existing TV.


To receive Sky Digital satellite TV, Old and
new customers will need a brand New
Satellite Dish & Decoder. The box will also
have to be connected to the telephone socket


To receive Digital cable services, we need a
new digital set top box which will also be
upgraded automatically to old customers from
the local telephone company.


Set Top box




Set Top box is needed, as the boxes
are being made by Nokia, Phillips,
Toshiba, Sony & Pace, with another
new contract just being signed by
Northern Telecom and Cable &
Wireless for Pace to supply their home
set top boxes for the coming summer
2000 launch for Digital Cable.




PCS


Personal Communications Services, a whole family
of next
-
generation wireless communications services
that include new categories of wireless voice, two
-
way messaging and high
-
speed data transmission
using lightweight, multi
-
function,


PCS networks operate similarly to other radio
technologies in that signals are sent using a series of
transmitters (also called base stations) mounted on
buildings, free
-
standing towers and other structures.


PCS phones send and receive digital signals via
these base stations and a system of computerized
switches.


GSM


The "Global System for Mobile
Communications" or GSM is an international
digital radio standard created by the
European Telecommunications Standards
Institute (ETSI). PCS network uses GSM
technology.






Wireless Application Protocol



Wireless Application Protocol (WAP) provides
a universal open standard for bringing
internet content and advanced value added
services to mobile phones and other wireless
devices. It is the platform for a new
generation of "media phones" which will
enable users to easily access web based
interactive information services and
applications from the screens of their mobile
phones.


The Need


WAP gives mobile access to information
and services for small wireless devices
as i.e. mobile phones and PDAs.


WAP takes care of the limitations those
kinds of devices have and the demand
of flexibility they need.




Small display screens with low
resolution.


The input devices have limited capacity
and mostly no pointing device


Low power CPU, less memory and less
reliable power supply.


The network offers less bandwidth and
less reliable contact.



The Limitations

The Flexibility


When it is compared to i.e.
HTML
-
C, the WAP
-
standard
does not specify how a WAP
-
device should look like.

Importance


It is important because the
combination of mobile phone
and the Internet is the trend.
WAP is the standard for this.




The operation



The WAP standard was created
because the world's leading companies
in the business of telecommunication
saw the need for a global standard for
wireless communication with extended
services on a small handheld device.


WAP combines two techniques;
wireless communication and the
Internet.



WAP architecture


Application Layer


It is based on a combination of Mobile Telephony and World
Wide Web

technologies. and consist of the following


Session layer


Wireless Session Protocol (WSP) This layer offers mainly
two session

services; connection session and connectionless session.


Transaction Layer


It provides a light
-
weight transaction
-
oriented protocol that is
suitable

for mobile clients.

WAP architecture


Security Layer


It is based on the industry
-
standard TLS (Transport Layer
Security) protocol,


It can be used for secure communication between terminals
and business cards.


Transport Layer


It operates above the data capable bearer services and
offers a consistent service to the upper layer protocols in the
WAP


Network Layer


It is the Wireless bearers and is designed to operate over a
variety

of bearer services, like SMS, CDMA, CSD and more.

WAP Gateway


The WAP Gateway is a device for converting
the TCP/IP protocols to the different WAP
protocols and vice versa. It is able to translate
HTML to WML.



Wireless Markup Language


WML (Wireless Markup Language) is similar
to HTML and is used to create pages to be
shown in a WAP
-
browser. A WAP
-
browser is
always included in a WAP
-
device.



WAP
-
browser


A WAP
-
browser (WAP micro
-
browser) interprets WML in a WAP
-
device. It is similar to a web
browser in a PC.



WMLScript


WMLScript is similar to JavaScript but there
are also differences.


WMLScript is precompiled, as WML is, before
it reaches the wireless device. WML contains
no WMLScripts, only references to
WMLScript URLs.


WAP version 1.2 has now been approved.
This version introduces WAP Push
Architecture, user agent profiles (UAPROF),
WDP
-
tunling,.



Use of PC to test WAP


We can use PC to test WAP, but cannot use an ordinary
web
-
browser to view a WAP
-
site. To be able to access a
WAP
-
site through Internet, we need a WAP
-
emulator in
PC. You can try the following URLs.


http://wap.combra.se/

The Nokia WAP Toolkit 1.1 is downloadable from
http://www.forum.nokia.com/developers/wap/wap.html


Ericsson has a similar SDK, downloadable from
http://mobileinternet.ericsson.se/emi/


Dynamical Systems Research offers a commercial
development

environment, read more at http://www.wap.net/devkit/


Slob
-
Trot Software has the WML
-
browser WinWAP,
downloadable

at http://www.slobtrot.com/winwap/


secure transactions using WAP


WAP 1.1 has a security
-
layer, in the protocol
stack, named WTLS handling the security. A
strongly secure solution should be built using
an WAP
-
server connected directly to the
GSM
-
network. Security is not though
something that comes automatically and
applications demanding a high level of
security must be developed with great care.




Conversion from HTML to WML


There are systems for automatic
conversion from HTML to WML. How
well this works in reality depends on the
device, the application and the
complexity of the HTML
-
page to
convert.



HTML
-
C


This is a variant of HTML with some
added tags to make it usable on a
cellular like wap
-
device. NTT Docomo,
the biggest cellular phone operator, has
used it in Japan since 1999. Many
people see this as a first step towards
WAP.

HDML (Handheld Device Markup
Language)



has been available since 1996. It is
developed by Phone.com, which also is one
of the promoters to WAP. In USA HDML is
more common than WAP so far, because
HDML came first. A HDML FAQ is found at
this site http://www13.w3.org/TR/NOTE
-
Submission
-
HDML
-
FAQ



3G


A new radio communications technology that will create
a "bit pipe" for providing mobile access to internet
-
based
services..


In the near future, mobility won't be an add
-
on: it will
become a fundamental aspect of many services. We'll
expect high
-
speed access to the internet, entertainment,
information and electronic commerce.


3G services will add an invaluable mobile dimension to
services that are already becoming an integral part of
modern business life:.


We will use 3G services enter our day
-
to
-
day lives in all
sorts of new ways: for example, in shopping, banking, or
playing interactive computer games over the Net.