Wireless LAN and its technologies. Wireless Access Protocol

1. By: Surbhi Sharma

2. WLAN
 A wireless local area network (WLAN) links two or more devices using some
wireless distribution method (typically spread-spectrum ), and usually
providing a connection through an access point to the wider Internet.
 WLAN uses the unlicensed Industrial, Scientific, and Medical (ISM) band that
different products can use as long as they comply with certain regulatory
rules.
 WLAN is also known as Wireless Fidelity or WiFi in short.
 There are many products which use these unlicensed bands along with
WLAN.

3.  Wireless LANs provide
Flexibility
Portability
Mobility
Ease of Installation

4. Wireless LAN Applications
Medical Professionals
Education
Temporary Situations
Airlines
Security Staff
Emergency Center

5. Types of WLANS
 The IEEE 802.11 has two basic modes of operation:
1. Ad hoc mode
2. Infrastructure mode

6. Ad hoc mode- In ad hoc mode, mobile units
transmit directly peer-to-peer.

7. Infrastructure mode- In infrastructure mode, mobile
units communicate through an access point that serves
as a bridge to other networks (such as Internet or LAN)

8. WIRELESS LAN TECHNOLOGIES:
 In general , wireless LANs are categorized according to
the transmission technique which is employed.
 Mainly 3 technologies are use din wireless LANs:
i. Infrared (IR) LANs
ii. Radio Waves LANs
iii. Microwave

9. 1. Infrared (IR) LANs
 They use the same signal frequencies used on fiber optic links. IR
systems detect only the amplitude of the signal and so interference is
greatly reduced.
 These systems are not bandwidth limited and thus can achieve
transmission speeds greater than the other systems.
 Infrared transmission does not require a license from the FCC to
operate.
 IR signals cannot penetrate opaque objects. This means that walls,
dividers, curtains, or even fog can obstruct the signal.
 IR technology was initially very popular because it delivered high data
rates and relatively cheap price.
 The drawbacks to IR systems are that the transmission spectrum is
shared with the sun and other things such as fluorescent lights.

10. 2. Radio Frequency
 This type of LAN makes use of spread spectrum
transmission technology.
 In general, these LANs operate in the ISM(Industrial,
Scientific and Medical) bands so that no FCC licensing
in needed for their use in United States.
 Radio frequency systems must use spread spectrum
technology in the United States.

11. 3. Microwave
 This type of LAN does not use spread spectrum.
 These LANs operate at microwave frequencies.
 Some of these products operate at frequencies that need
FCC licensing, while others use one of the unlicensed ISM
bands.
 The big advantage to MW systems is higher throughput
achieved because they do not have the overhead involved
with spread spectrum systems.

12. Wireless Local Loop
 WLL stands for Wireless Local Loop and it is basically the use of radio
to provide a telephone connection to the home. It is sometimes called
radio in the loop (RITL) or fixed-radio access (FRA).
 WLL is a system that connects subscribers to the local telephone station
wirelessly.
 When WLL connects subscribers to the public switched telephone
network (PSTN), radio signals are used as a substitute for copper for all
or part of the connection between the subscriber and the switch.
 Included in this is: cordless access systems, proprietary fixed radio
access, and fixed cellular systems.

13. WAP
(Wireless Application/Access
Protocol)

14. WAP- Wireless Application/
Access Protocol
 An open, global specification that empowers mobile users with wireless devices to
easily access and interact with internet information and services instantly.
 The wireless industry came up with the idea of WAP. The point of this standard was
to show internet contents on wireless clients, like mobile phones.
 Wireless: Lacking or not requiring a wire or wires pertaining to radio
transmission.
 Application: A computer program or piece of computer software that
is designed to do a specific task.
 Protocol: A set of technical rules about how information should be
transmitted and received using computers.

15.  WAP stands for Wireless Application Protocol
o WAP is an application communication protocol
o WAP is used to access services and information
o WAP is inherited from Internet standards
o WAP is for handheld devices such as mobile phones
o WAP is a protocol designed for micro browsers
o WAP enables the creating of web applications for mobile
devices.
o WAP uses the mark-up language WML (not HTML) WML
is defined as an XML 1.0 application

16. The basic AIM of WAP is to provide a web-like
experience on small portable devices - like mobile phones
and PDAs.

17. Purpose of WAP
To enable easy, fast delivery of relevant information and services to mobile users.
Type of devices that use WAP
Handheld digital wireless devices such as mobile phones, pagers, two-way radios,
smart phones and communicators -- from low-end to high-end.
WAP works with most Wireless networks such as:
CDPD, CDMA, GSM, PDC, PHS, TDMA, FLEX, ReFLEX, iDEN, TETRA, DECT,
DataTAC, Mobitex.

18. Operating systems that are compatible with WAP
•WAP is a communications protocol and an application environment.
•WAP is independent of OS that means WAP can be implemented on any
OS.
•It can be built on any operating system including Palm OS, EPOC 32,
Windows CE, FLEXOS, OS/9, Java OS, etc. It provides service interoperability
even between different device families.

19. Architecture Overview
 WWW programming model is optimized and extended
to match characteristics of the wireless environment
 Utilizes proxy technology to connect between the
wireless domain and WWW.
 Before we describe WAP model, first we would like
you to understand how Standard Internet works.

20. World-Wide Web Model
CGI,
Scripts,
Etc.
Content
Web Server
Client
Web
Browser
Request
(URL)
Response
(Content)
The figure below shows how a WWW client request a resource
stored on a web server. On the Internet standard communication
protocols, like HTTP and Transmission Control Protocol/Internet
Protocol (TCP/IP) are used.

21. WAP Programming Model
CGI,
Scripts,
Etc.
Conten
t
Web Server
Client
WAE
User
Agent
Request
(URL)
Response
(Content)
Gateway
Encoders
And
Decoders
Encoded
Request
Encoded
Response
The figure below shows the WAP programming model. Note, the
similarities with the Internet model. Without the WAP
Gateway/Proxy, the two models would have been practically
identical.

22. How WAP Model Works?
 When it comes to actual use, WAP works like this:
 The user selects an option on their mobile device that has a URL with Wireless
Markup language (WML) content assigned to it.
 The phone sends the URL request via the phone network to a WAP gateway
using the binary encoded WAP protocol.
 The gateway translates this WAP request into a conventional HTTP request for
the specified URL and sends it on to the Internet.
 The appropriate Web server picks up the HTTP request.
 The server processes the request just as it would any other request.
 The Web server adds the HTTP header to the WML content and returns it to
the gateway.
 The WAP gateway compiles the WML into binary form.
 The gateway then sends the WML response back to the phone.
 The phone receives the WML via the WAP protocol.
 The micro-browser processes the WML and displays the content on the screen.

23.  WAP Device
- Is used to access WAP applications and
content. It might be a PDA, handheld computer.
 WAP Client
- Entity that receives content from Internet via a
WAP Gateway. This is usually the WAP Browser.
 WAP Content/Origin/Application Server
- Element in the network where the information
or web/WAP applications resides.

24. WAP Proxy
- Acts both as a client and as a server in the network.
Typically has
 Protocol gateway : translates requests from the WAP
protocol stack to WWW protocol stack
 Content encoders and decoders : translate WAP content
into compact encoded formats to reduce the size of data
over the network
It allows content and applications to be hosted on
standard WWW servers and developed using proven
WWW technologies such as CGI scripting

25.  WAP Gateway
- Intermediary element used to connect two different
types of network. It receives request directly from
the clients as if it actually were the origin server that
clients want to receive the information form. The
clients are usually unaware that they are speaking to
the Gateway.
 WAP Browser
 Software running on the WAP device that interprets the
WAP content arriving from the internet and decides how
to display it on WAP device.

26. WML
 WML – Wireless Markup Language formerly
called HDML (Handheld Devices Markup
Language)
 Is a tag language that allows the text portions of
Web Pages to be presented on cellular phones and
Personal Digital Assistants (PDAs) via wireless
access.
 WML is used for delivering data to WAP.

27. ADVANTAGES
The ADVANTAGES that WAP can offer over these other methods are the following:
•open standard, vendor independent
•network-standard independent
•transport mechanism–optimized for wireless data bearers
•application downloaded from the server, enabling fast service creation and
introduction, as opposed to embedded software

28. DISADVANTAGES of WAP
 Small screens: For web phones, there's an incredibly small viewing
area; palmtops are barely better.
 Speed of access: All devices have slow access.
 Limited or fragmented availability: Wireless web access is sporadic in
many areas and entirely unavailable in other areas.
 Price: Many technology limitations are being addressed by higher-end
devices and services. But the entry price for a good wireless web
palmtop with decent display, keyboard, and speed is easily $700 to
$900, not including monthly access.
 Lack of user habit: It takes some patience and overcoming the learning
curve to get the hang of it -- connecting, putting in an address, typing.
Users just aren't used to the idea and protocol yet.
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