Wireless Communications (Edexcel IGCSE ICT)

Wi-Fi

What is Wi-Fi?

• Wireless fidelity (Wi-Fi) is a common standard for wireless networks

• Wi-Fi is common in most homes and offices to connect devices such as laptops, tablets & smart phones

• Using Wi-Fi, devices communicate with a hotspot or a wireless access point (WAP), which can be a standalone device or built into a router or switch 

• Wi-Fi may be preferred over Bluetooth when:

  • High speed data transfer is required

  • Long range communication is required

  • Many devices are needed to be connected at the same time

Bluetooth

What is Bluetooth?

• Bluetooth is another common standard for wireless networks

• Bluetooth is common in most homes and offices to connect devices such as headphones, controllers, keyboards & mice

• Bluetooth is used typically for a direct connection between two devices 

• When two devices pair, they both exchange a cryptographic key

• The keys are used to generate a secret shared key which is used to encrypt the data between the two devices and create a Wireless Personal Area Network (WPAN)

• Connected devices continuously change their transmitting frequency between 79 different channels to avoid interference and improve the reliability of the connection

• This is known as the frequency hopping spread spectrum (FHSS)

Differences between Bluetooth and Wi-Fi

GPS

What is GPS?

• Global Positioning System (GPS) is a satellite system used to track the exact location of an object

• GPS uses orbiting satellites to receive, amplify and transmit signals

• Radio frequencies are used to communicate between satellites and ground stations

• GPS requires a direct line of sight

3G & 4G

What is 3G & 4G?

• 3G and 4G are references to the 3rd and 4th generation of mobile data networks

• They provide mobile devices with wireless access to the internet

• Each generation has a faster transfer rate and an improved capacity for more users

  • 3G - 256 Kbps (kilobits per second)

  • 4G - 100+ Mbps (megabits per second)

• The current generation (5G) has even faster speeds and lower latency

Infra-red (IR)

What is infra-red?

• Infra-red is a wireless communication method used to transfer very small amounts of data to a device in direct line of sight

• Commonly used in remotes to control devices such as:

  • Televisions

  • Audio receivers

  • Home entertainment equipment etc.

• Uses light waves which can cause:

  • Walls or obstacles to block the signal

  • Sunlight to affect the signal

• It is a reliable and cost effective solution for many short-range wireless communication needs

NFC

What is NFC?

• Near field communication (NFC) is a subset of RFID which allows communication between two devices in very close proximity

• NFC can be either:

  • Passive - uses energy from the reader

  • Active - has it's own power source

• Smartphones use active NFC to allow contactless payments by tapping a smartphone on a reader

• Smartphones can also exchange data using NFC by tapping together (usually back to back)