Wireless Networks (Cambridge (CIE) IGCSE ICT)
Revision Note
What is a wireless network?
A wireless network is a network where connections are made using radio waves to transmit data through the air
The most common types of wireless connections are:
Wi-Fi
Bluetooth
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
Advantages | Disadvantages |
|---|---|
Portability - Easy to move around, location is only limited by range | Speed - Slower data transfer than Ethernet |
Cost - Less expensive to setup and add new devices | Security - Less secure than Ethernet |
Compatibility - Most devices are manufactured with a built in Wi-Fi adapter | Range - Relies on signal strength to the WAP, signals can be obstructed (up to 100m) |
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)
Advantages | Disadvantages |
|---|---|
Compatibility - Ideal for personal devices and ad-hoc connections | Speed - Very slow transfer speeds |
Power - Very low power consumption | Security - Data can be intercepted by anyone in range |
| Range - Short range (30m) |
Differences between Bluetooth and Wi-Fi
| Bluetooth | Wi-Fi |
|---|---|---|
Maximum number of connections | 7 | 30 |
Transmission frequency | 2.4Ghz | 2.4Ghz, 5Ghz |
Maximum range (meters) | 30 meters | 100 meters (depending on obstructions) |
Maximum transfer speed (Depending on the standard being used) | 3 Mbytes / Sec | 75 Mbytes / Sec |
Worked Example
A school IT team is trying to determine what technology they should use to connect students' tablets around the school for data transfer and are unsure whether to choose Wi-Fi or Bluetooth technology.
Consider the advantages and limitations of both and justify your answer
[7]
Answer
WiFi offers significantly faster transfer rates compared to Bluetooth [1]
so students will be able to upload and download files faster [1]
WiFi coverage can be over a much larger area compared to Bluetooth [1]
so that students will be able to access resources wherever they are in the school [1]
Bluetooth however, is easy to set up [1]
students can transfer data without the school having to invest in expensive infrastructure [1]
Given the current situation, the school is in, the preferred choice for connecting student's tablets would be Wi-Fi [1]
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