basic concepts in wireless lan

Basic Concepts in Wireless LAN

Shashikant V. AthawaleAssistant Professor

Department of Computer Engineering, AISSMS COE ,Pune

Wireless Standard

Wireless LAN And Technology

Wireless Application Protocol

Content

There have been 5 major milestones in wireless internet communication.◦ 802.11 – Released in 1997, the original wireless protocol◦ 802.11a – Released in late 1999◦ 802.11b – Released in late 1999◦ 802.11g – Released in mid 2003◦ 802.11n – Released in 2009

Wireless Standard

The ORIGINAL wireless protocol.◦ Security implemented via WEP

Wired Equivalent Privacy (Legacy) Provided Bandwidth

◦ 1 or 2 Mbit/s due to use of CSMA/CA Relatively Unpopular Low interoperability due to loose specifications Used DSSS Considered Legacy and no longer used

802.11 – 1997

One of two amendments to the original 802.11

specification released simultaneously

Provided up to 54 Mbit/s bandwidth

Uses OFDM

◦ Orthogonal Frequency-Division Multiplexing

Transmits a signal over several sub signals for higher efficiency

802.11a

Second of two amendments released in 1999

Provided up to 11 Mbit/s bandwidth

Uses DSSS

◦ Direct-Sequence Spread Spectrum

Transmits a signal over several sub signals for higher efficiency

802.11b

Pretty much the most common wireless network in use

today.

Operates on 2.4Ghz band

Provides up 54Mbit/s bandwidth

◦ 108Mbit/s with special implementations

Uses OFDM for modulation

Adopted quickly after release for cheap and high bandwidth

802.11g

Newest member of the 802.11 family.

Has rated 600Mbit/s bandwidth

Introduces MIMO

◦ Multiple-Input Multiple-Output

OFDM Modulation

◦ Uses higher frequencies for increased number of carrier waves

802.11n

A wireless LAN uses wireless transmission medium

Used to have high prices, low data rates, occupational

safety concerns, and licensing requirements

Problems have been addressed

Popularity of wireless LANs has grown rapidly.

Wireless LAN And Technology

Saves installation of LAN cabling Eases relocation and other modifications to network structure However, increasing reliance on twisted pair cabling for LANs

◦ Most older buildings already wired with Cat 3 cable◦ Newer buildings are prewired with Cat 5

Wireless LAN to replace wired LANs has not happened In some environments, role for the wireless LAN

◦ Buildings with large open areas Manufacturing plants, stock exchange trading floors, warehouses Historical buildings Small offices where wired LANs not economical

May also have wired LAN◦ Servers and stationary workstations

Application-LAN Extension

Single Cell Wireless LAN Configuration

Multi-Cell Wireless LAN Configuration

Infrastructure Wireless LAN

Peer-to-peer network

Set up temporarily to meet some immediate need

E.g. group of employees, each with laptop or palmtop,

in business or classroom meeting

Network for duration of meeting

Ad Hoc Networking

Ad Hoc LAN

Same as any LAN: High capacity, short distances, full connectivity, broadcast capability.

Throughput: efficient use wireless medium Number of nodes:Hundreds of nodes across multiple cells Connection to backbone LAN: Use control modules to connect to both types of

LANs Service area: 100 to 300 m Low power consumption:Need long battery life on mobile stations Transmission robustness and security:Interference prone and easily

eavesdropped Collocated network operation:Two or more wireless LANs in same area License-free operation Handoff/roaming: Move from one cell to another Dynamic configuration: Addition, deletion, and relocation of end systems

without disruption to users

Wireless LAN Requirements

Infrared (IR) LANs: Individual cell of IR LAN limited to single room◦ IR light does not penetrate opaque walls

Spread spectrum LANs: Mostly operate in ISM (industrial, scientific, and medical) bands◦ No Federal Communications Commission (FCC) licensing is

required in USA Narrowband microwave: Microwave frequencies but

not use spread spectrum◦ Some require FCC licensing

Technology

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 Application Protocol

WAP is an application communication protocol WAP is used to access services and information WAP is inherited from Internet standards WAP is for handheld devices such as mobile phones WAP is a protocol designed for micro browsers WAP enables the creating of web applications for

mobile devices. WAP uses the mark-up language WML (not HTML)

WML is defined as an XML 1.0 application

Continue…..

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, TETRA, DECT, DataTAC, Mobitex.

Purpose of WAP

Leverage existing standards whenever possible

Define a layered, scalable and extensible architecture

Support as many wireless networks as possible

Optimize for narrow-band bearers with high latency

Optimize for efficient use of device resources

Provide support for secure applications and

communication

WAP Architecture Requirements

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

Architecture Overview

World-Wide Web Model

WAP Programming Model

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.

Continue….

WAP Network ExampleWeb Server

WirelessNetwork

WAPProxy

HTMLFilter

WTAServer

WAPClient

WML

WMLHTML

Components of WAP Architecture

Other ServicesAnd Applications

Transport Layer (WDP)

Security Layer (WTLS)

Transaction Layer (WTP)

Session Layer (WSP)

Application Layer (WAE)

GSM CDMA PHS IS-136 CDPD PDC-P FLEX Etc…

General-purpose application environment based on a combination of WWW and mobile telephony technologies.

It defines the user interface on the phone. It contains WML and WTA (Wireless Telephony Application).

Primary objective – interoperable environment. WAE includes a micro-browser (Client software designed to

overcome challenges of mobile handheld devices that enables wireless access to services such as Internet information in combination with a suitable network) server environment which provides◦ WML◦ WML script◦ WTA◦ Content formats

Wireless Application Environment

• WAP provides a markup language and a transport protocol that open the possibilities of the wireless environment and give players from all levels of the industry the opportunity to access an untapped market that is still in its infancy.

• The bearer-independent nature of WAP has proved to be a long-awaited breath of fresh air for an industry riddled with multiple proprietary standards that have suffocated the advent of a new wave of mobile-Internet communications. WAP is an enabling technology that, through gateway infrastructure deployed in mobile operator's network, will bridge the gap between the mobile world and the Internet, bringing sophisticated solutions to mobile users, independent of the bearer and network.

• Backed by 75 percent of the companies behind the world's mobile telephone market and the huge development potential of WAP, the future for WAP looks bright.

Summary

http://en.wikipedia.org/wiki/IEEE_802.11

http://

www.cisco.com/en/US/prod/collateral/wireless/ps5678/

ps6973/ps8382/prod_white_paper0900aecd806b8ce7_

ns767_Networking_Solutions_White_Paper.html

www.palopt.com.au/wap

References

Books◦ Mobile communications: Jochen Schiller, Addison Wesley 2000◦ Understanding WAP:

Official Website (specifications)◦ www.wapforum.org

Technical/Developer Info and tools◦ www.palopt.com.au/wap◦ www.wap.net

Major players◦ www.nokia.com/wap◦ www.ericsson.se/wap◦ phone.com

OpenSource effort◦ www.wapgateway.org (Kannel WAP gateway project)

References

THANK YOU…!!!