Basics of Wi-Fi Technology

Basics of Wi-Fi Technology

Introduction:

Wireless technology is an alternative to WIRED TECHNOLOGY, which is commonly used, for connecting devices in wireless mode.

Wi-Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks (WLANs). Wi-Fi Network connect computers to each other, to the internet and to the wired network.

History:

The term "Wi-Fi" stands for "Wireless Fidelity“. Wi-Fi" was coined by a brand consulting firm called interband Corporation. Wi-Fi was invented in 1991 by NCR corporation /AT&T/AT&T in Nieuwegein , the Netherlands. The first wireless product was brought on the market under the name WaveLAN with speeds of 1Mbit/s to 20Mbit/s.

The Wi-Fi Technology:

Wi-Fi Networks use Radio Technologies to transmit & receive data at high speed:

• IEEE 802.11b

• IEEE 802.11a

• IEEE 802.11g

Purpose:

The main aims of Wi-Fi are the following:

• make access to information easier.
• ensure compatibility and co-existence of devices.
• eliminate cabling and wiring.
• eliminate switches, adapters, plugs, pins and connectors.

Elements of a WI-FI Network

• Access Point (AP)
• Wi-Fi cards
• Safeguards

Hotspot:

• A hotspot is a venue that offers Wi-Fi access to the Internet.
• Commercial Hotspots
• Billing
• Free Wi-Fi hotspots
• Security Concerns

Building a wireless Network:

• create a wireless network with a wireless access point
• Wireless router is used to connect the computers to one another,to a printer and to the internet.
• Most routers let you use a Web interface to change your settings. One can select: (1.)The name of the network, i.e; service set identifier. (2.)The channel that the router uses. (3.)Your router's security options.
• To keep your network private, you can use one of the following methods: (a.) WiFi Protected Access (WPA) (b.) Media Access Control (MAC)

How a Wi-Fi Network Works:

• Basic concept is same as Walkie talkies.
• A Wi-Fi hotspot is created by installing an access point to an internet connection.
• An access point acts as a base station.
• When Wi-Fi enabled device encounters a hotspot the device can then connect to that network wirelessly.
• A single access point can support up to 30 users and can function within a range of 100 – 150 feet indoors and up to 300 feet outdoors.
• Many access points can be connected to each other via Ethernet cables to create a single large network.

Wi-Fi Network Topologies:

1. AP-based topology (Infrastructure Mode)
2. Peer-to-peer topology (Ad-hoc Mode)
3. Point-to-multipoint bridge topology

Examples:

• AP-based topology (Infrastructure Mode)

• Peer-to-peer topology (Ad-hoc Mode)

• Point-to-multipoint bridge topology

Wi-Fi Applications:

1. Home
2. Small Businesses or SOHO
3. Large Corporations & Campuses
4. Health Care
5. Wireless ISP (WISP)
6. Travellers

Wi-Fi Security Threats:

1. Wireless technology doesn’t remove any old security issues, but introduces new ones
2. Eavesdropping
3. Man-in-the-middle attacks
4. Denial of Service

Wi-Fi Security:

The requirements for Wi-Fi network security can be broken down into two primary components:

1. Authentication

• User Authentication
• Server Authentication

2. Privacy

Wi-Fi Security Techniques:

• Service Set Identifier (SSID)
• Wired Equivalent Privacy (WEP)
• 802.1X Access Control
• Wireless Protected Access (WPA)
• IEEE 802.11i

Uses:

• A Wi-Fi enabled device such as a PC, game console,mobile phone, MP3 player or PDA can connect to the Internet when within range of a wireless network connected to the Internet.
• Wi-Fi can make access publicly available at Wi-Fi hotspots provided either free of charge or to subscribers to various providers.
• Increasing the number of Wi-Fi access-points provides redundancy, support for fast roaming and increased overall network-capacity by using more channels or by defining smaller cells.

Advantages:

• Mobility
• Ease of Installation
• Flexibility
• Cost
• Reliability
• Security
• Use unlicensed part of the radio spectrum
• Roaming
• Speed

Limitations:

• Interference
• Degradation in performance
• High power consumption
• Limited range

Basic concepts of WiMAX

Basic concepts of WiMAX

WiMAX means Worldwide Interoperability for Microwave Access

• WiMAX based on the IEEE802.16 protocol is a broadband wireless technology applied to the Metropolitan Area Network (MAN).
• It complies the "Broadband + Wireless" trend. WiMAX features the Orthogonal Frequency Division Multiplex Access (OFDMA), Multiple Input Multiple Output (MIMO), and other advancedtechnologies to maintaain its broadband advantage.
• It is called 3.5G or 4G technology. In October of 2007,it has become the 4th standard of 3G technology.

Protocols:

WiMAX is based on the 802.16 protocol that has two standards:

• 802.16d Fixed Broadband radio access standard: It specifies the air interface layer between the fixed access terminals and the BTS.
• 802.16e Mobile Broadband radio access standard: It supports the mobile stations. Moreover it supports both the fixed broadband radio access system and mobile broadband radio access system.

Technical Benefits of WiMAX:

1. Advanced technical functions:

• It incorporates multiple technologies including OFDMA, MIMO, AMC, HARQ etc.

2. Wide coverage and high throughput:

• The maximum coverage distance of a BS is 50km. The typical coverage distance is 6km to 10km.
• The maximum throughput of each sector is 75Mbit/s.

3. Easy to Expand:

• It is easy to add new sectors.
• It is easy to plan the channel bandwidth.

4. Low risks of overhead and investment

5. Broadband access

Technical Specifications of WiMAX:

802.16d standard:

Bandwidth (MHz): 1.75-20

Frequency (GHz): 2-11

Mobility: Fixed or Roaming

Transmission technology: Multi carrier, OFDM

Multiple access: OFDMA

Spectrum Assignment Unit: Sub-channel

Duplex mode: TDD,FDD

Peak rate (Mbit/s): 75 Mbps (20MHz)

Modulation mode:DL:BPSK,QPSK,16QAM,64QAM; UL:bpsk,qpsk,16QAM

Inter-cell handovers: No

Enhanced Technology: Intelligent antenna, MIMO, HARQ,AMC

Access control: The BS periodically allocates bandwidths to the MS and provides opportunities for periodic unicast polling. The MSs access the network based on priority.

QoS: Supporting five QoS class standards including UGS,ERtPS,RtPS,NrtPS and BE.

Battery saving mode: No

802.16e standard:

Bandwidth (MHz): 1.25-20

Frequency (GHz): 2-6

Mobility: Middle-rate mobile station (<120km/h)

Transmission technology: Multi carrier,OFDMA

Multiple access: OFDMA

Spectrum Assignment Unit: Sub-channel

Duplex mode: TDD,FDD

Peak rate (Mbit/s): 15 Mbps (5MHz), 30 MHbps (10MHz)

Modulation mode:DL:BPSK,QPSK,16QAM,64QAM; UL:bpsk,qpsk,16QAM

Inter-cell handovers: Yes

Enhanced Technology: Intelligent antenna, MIMO, HARQ,AMC

Access control: The BS periodically allocates bandwidths to the MS and provides opportunities for periodic unicast polling. The MSs access the network based on priority.

QoS: Supporting five QoS class standards including UGS,ERtPS,RtPS,NrtPS and BE.

Battery saving mode: Supporting idle and sleep modes

Global Spectrum Distribution of WiMAX:

Primary frequency bands:

• 2.3G: 2.3 - 2.4 GHz
• 2.5G: 2.496 - 2.690 GHz
• 3.5G: 3.4 - 3.6 GHz

QoS - Based Services:

• Unsolicited Grant Service(UGS): VoIP (without silence suppression)
• Extended Real-time Polling Service(ertPS): VoIP (with silence suppression)
• Real-time Polling Service(rtPS): MPEG video
• Non-Real-time Polling Service(nrtPS): FTP service
• Best Effort(BE): Network browse, e-mail

Network Elements of WiMAX:

• MSS (Mobile Subscriber Station)
• ASN (Access Service Network): The ASN consists of the Base Station (BS) and the Access Service Network-Gateway(ACN-GW). The ASN manages the IEEE802.16e air interface and enables the MS to access multiple CSNs.
• CSN (Connect Service Network): The CSN is connected to the internet, ASP, PLMN, and other networks. It provides Authentication, Authorization and Accounting (AAA), roaming between different NSPs (Network Service Providers), IP address management, location management, mobility management, connection for multiple services, policy management, and QoS management.
• NAP (Network Access Provider)
• NSP (Network Service Provider)

Networking features of WiMAX:

• Independent networking
• Hybrid networking with 2G/3G
• Easy to construct the network
• Low cost