Wi-fi (Wireless fidelity) Information Communication Technology.

Wireless fidelity

INTRODUCTION

Wi-Fi is THE name for popular wireless technology that uses radio waves to provide high-speed Internet and network connections. According to Google:-a facility allowing computers, smart phones, or other devices to connect to the Internet or communicate with one another wirelessly within a particular area.

Wi-Fi —used to certify the interoperability of wireless computer networking devices 

History of Wi-fi

In 1971The University of Hawaii provides the first public demonstration of a wireless packet data network, ALOHAnet, operating on UHF (Ultra High Frequency) radio waves. The system includes seven computers spread across four islands.

In 1992 and 1996, the Australian Radio astronomer Dr. John O'Sullivan developed Wi-Fi as a by-product of a research project, “A failed experiment to detect exploding mini black holes the size of an atomic particle".

1997 802.11 Protocol The first version of the 802.11 protocol,2Mbps link speeds

➢In 1999, the WI-FI ALLIANCE formed as a trade association to hold the Wi-Fi trademark.

➢. In April 2009 Wi-Fi used by different organizations, 14 technology companies agreed to pay CSIRO $1 billion for infringements on CSIRO patents. This led to Australia labeling Wi-Fi as an Australian invention 

Wi-Fi Alliance

 Wi-Fi Alliance is a non-profit organization 

 that promotes Wi-Fi technology and certifies Wi-Fi product's 

 conformity to certain standards of interoperability. IEEE 802.11 

 Formation1999; 20 years ago 

 HeadquartersAustin, Texas, United States 

 Websitewww.wi-fi.org 

 Formerly called Wireless Ethernet Compatibility Alliance 

 200 MEMBER COUNTRIES 

 Performance: 

 CONFORMANCE Critical elements of the IEEE 802.11 standard 

 Compatibility

RADIO FREQUENCY

Transmission type Frequency Wavelength Very low frequency (VLF) 9–30 kHz 33–10 km 

Low frequency (LF) 30–300 kHz 10–1 km 

Medium frequency (MF) 300–3000 kHz 1000–100 m 

High frequency (HF) 3–30 MHz 100–10 m 

Very high frequency (VHF) 30–300 MHz 10–1 m 

Ultra-high frequency (UHF) 300–3000 MHz 1000–100 mm 

Super high frequency (SHF) 3–30 GHz 100–10 mm 

Extremely high frequency (EHF)B 30–300 GHz 10–1 mm

Wi-FI Topologies

1) Peer-to-peer topology (Ad-hoc Mode) 

2) AP-based topology (Infrastructure Mode) 

3) POINT TO MULTIPOINT TOPOLOGY

BAND/Channels

 Direct communication between wireless stations, whether it be in an ad-hoc network or an infrastructure network, happens on a channel: a specified frequency band for the travel of electromagnetic signals. 

 2.4 GHz  5 GHZ

PROTOCOL IEEE 802.11 A/B/G/AC/AF/…..

1) 802.11-(1997) 2) 802.11b (1999) 3) 802.11g (2003) 4) 802.11n (2009) 5) 802.11a (2012) 6) 802.11ac (2013) 7) 802.11ad (2010 8) 802.11af (2014)

IEEE 802.11a 

1. introduced in 2001 

2. 5.0Ghz radio spectrum 

3. 54Mbps (theoretical speed) 

4. 15-20Mbps (actual speed) 

5. 50-75 feet range 

6. more expansive 

7. not compatible with IEEE 802.11b

WIFI NETWORK

 Access Point (AP) -The AP is a wireless LAN transceiver or “base station” that can connect one or many wireless devices simultaneously to the Internet. 

 Wi-Fi cards -They accept the wireless signal and relay information. They can be internal and external. 

 Safeguards - Firewalls and anti-virus software protect networks from uninvited users and keep information secure

Advantages

1) Mobility 2) Ease of Installation 3) Flexibility 4) Cost 5) Reliability 6) Security 7) Use unlicensed part of the radio spectrum 8) Roaming 9) Speed

Disadvantages

1. Slower Data Transfer - rate decreases (to individual computer) when the number of clients or computers connected with wifi network increases. 

2. SECURITY - Full security is difficult to achieve due to the wifi connection being wireless in nature. It requires proper security authentication protocols and configurations 

3. LIMITED RANGEWiFi - access is limited to about 30 to 100 meters (i.e. 100 to 300 feet) 

4. JAMMERS 

5. HACKING