Networking

Describe and explain hardware and technologies for wireless connections

The definition and purpose of Wi-Fi

Wi-Fi is a wireless networking technology providing high-speed Internet and network connections.

Connecting to a wireless network

What’s needed is an ISP (internet service provider), modem and wireless router (which are often combined) and a device with an NIC.

Wireless components

• NIC (network interface card).
• A station consists of a computer and an NIC.
• Stations share a radio frequency channel.
• WAP (wireless access point), which connects to a router that connects to a modem.

WAPs and modems are typically built into consumer routers these days.

SSID

Stands for Service Set Identifier.

• Identifies each network by a unique name.
• Used by devices so they know which wireless network to connect to.
• SSIDs can be set automatically or manually.
• SSIDs can be made hidden to make them harder to detect for security.
• SSIDs can be set to broadcast to wireless devices within range of an access point.

Securing a wireless network

Wireless networks are typically less secure than wired ones as unauthorised users are harder to spot, and transmitted data can be intercepted more easily.

Security measures include:

• WPA encryption.
• WPA2 encryption.
• Using a hidden SSID.
• MAC address whitelists (i.e. only allowing specific NICs to connect to the network).

CSMA/CA

CSMA/CA (carrier sense multiple access with collision avoidance) is needed to handle devices attempting to transmit to the same WAP simultaneously.

Hidden node problem and CSMA/CA with RTS/CTS

The hidden node problem is where, for instance, nodes A and B are within range of the WAP but not each other. This makes it so that neither can properly detect whether the channel is idle. RTS/CTS is used to fix this.

After CSMA/CA, instead of a node just sending the data straight away, a 'request to send' is sent to the WAP as an extra measure. If the channel is indeed clear, the WAP will respond with a 'clear to send', upon which the node will send the data as normal.