Data transmission speed is the number of bits per second that can be transmitted

Objectives

• Explain the purpose of WiFi.
• Be familiar with the components required for wireless networking.
  • wireless adapter
  • wireless access point
• Be familiar with how wireless networks are secured.
• Be familiar with the purpose of Service Set Identifier (SSID).

Wireless Network Basics

Wireless networking basics

'A wireless network uses radio waves, just like cell phones, televisions and radios do. In fact, communication across a wireless network is a lot like two-way radio communication. Here's what happens:

• A computer's wireless adapter translates data into a radio signal and transmits it using an antenna.
• A wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired Ethernet connection.

The process also works in reverse, with the router receiving information from the Internet, translating it into a radio signal and sending it to the computer's wireless adapter.' - from howstuffworks.com

A WiFi hotspot is simply an area with an accessible wireless network. The term is most often used to refer to wireless networks in public areas like airports and coffee shops.

Purpose of WiFi

• WiFi or Wi-Fi is a wireless technology that enables a device such as a PC, laptop, smartphone, tablet, printer or media player (music or movie) to connect to a network via a wireless access point(WAP) so they can access or share network resources.
• In 1999, the WiFi alliance was formed to establish international standards for WiFi interoperability.
• A typical WAP can have a range of 90 meters outdoor and 50 meters indoor. The range is affected by many other factors.

Components required for wireless networking

• A device needs a wireless network interface controller(could be a USB or PCI card).
• A device with a wireless network interface controller is called a station.
• All stations in the WAP range will listen to one radio frequency transmission.
• A WAP can connect to a router or be integral part of a router.
• The WAP tries to process all transmissions from all stations in its range as fast it can. Only one station can transmit data at a time. The more stations it has, the slower the communication becomes.

WiFi Security

Wireless Network Security

• When you trying to join a new WiFi network, if it is secured (password protected), you will be asked to choose either WPA and/or WPA2 secure scheme.
• WPA (WiFi Protected Access) and WPA2 (the newer generation set to replace WPA) are two security protocols developed by the WiFi Alliance.
• WPA-personal is one mode of WPA which is widely used in home and small office. It does not require a centralised server to work. WPA-personal works by encrypt communication using a 256-bit key. The WiFi password you normally use to join a network is part of the 256-bit key.
• WPA-enterprise is designed for enterprise networks and requires a RADIUS server. This requires a more complicated setup, but provides additional security.

SSID (Service Set Identification)

• SSID is the name for a local WiFi network, such as BTHub6-XTJG.
• SSID's purpose is to identify a WiFi network and also used for part of the encryption key.

CSMA/CA

CSMA/CA

• Carrier Sense Multiple Access/Collision Avoidance is a protocol used in wireless transmission to prevent collisions before they occur.
• Before transmission, a station listens for signals on the network to determine if the channel is free or another station is transmitting. If a signal is detected, then it waits for a random amount of time for the other station before re-listens again.
• Each station may optionally use a Request to Send(from the station)/Clear to Send(from the WAP) (RTS/CTS) after determining there is no station currently transmitting. Using RTS/CTS can avoid the problem with hidden stations - those stations whose signals are not visible to the listening station but only to the WAP due to outside the communication range.

By jjgarcia.tsc - http://commons.wikimedia.org/wiki/File:Csmaca_algorithm.png, Attribution, https://commons.wikimedia.org/w/index.php?curid=12661157

Location-based Wi-Fi services

• WiFi location can be thought as indoor GPS.
• Wi-Fi-based positioning systems are used where GPS is inadequate due (typically) to signal blockage.
• Retail businesses, hospitalities, healthcare and education are looking to use this technology to reach people.
• Example uses of (Location based services) LBS:
  • location based advertisements and coupons
  • retail centres can optimise store layouts based on typical customer traffic paths.
  • business owners can charge more for premium storefront or high-view ad spots.
  • personalise customer services such as personalised greeting and check-in on arrival.
  • hospitcals can use LBS for indoor navigation, tracking staff and patients, location-based messaging, asset management, location analytics, and in integrating with other clinical systems.
  • In a university campus, LBS can provide users with points of interests, such as restaurants, student meeting places, lectures and events, geo-fencing lecture contents, and in campus traffic patterns.

• The problem of Wi-Fi based indoor localization of a device consists in determining the position of client devices with respect to access points. Many techniques exist to accomplish this.
• Privacy concerns on how user location data being used and how long being retained.

What is the number of bits transmitted per second?

What term refers to the number of bits per second that can be transmitted over a communication medium?

Is the transmission capacity of a network stated in bits per second?

Is measured in bits per second and Mbps?