Wireless Networking
Last updated
Last updated
Wireless networks allow the devices in the network to communicate without needing a physical connection, such as wires.
WiFi is a wireless networking technology that provides high-speed Internet and network connections. The devices are connected to the internet via a wireless network access point (WAP).
To connect to a wireless network, we need:
ISP (internet service provider)
Modem and wireless router
Device with a network interface card (NIC), also known as a network interface controller
Wireless networks are secured by encrypting transmitted data using WPA or WPA2. WPA stands for WiFi protected access and requires that a new wireless client enters a password in order to connect to the network.
Another method of securing a wireless network is disabling SSID broadcast. SSID stands for service set identifier and is the name that identifies a wireless network. Disabling SSID broadcast stops wireless devices within range of the network from displaying that the network is available, only allowing those who know the SSID to connect.
A third method of securing a wireless network is to set up a MAC address filter. MAC (which stands for media access control) addresses are assigned to every wireless device by their manufacturer and are unique to that device. MAC address whitelists can be created to allow only specific devices to connect to a network. Likewise, MAC address blacklists can be used to block specific devices from connecting to a network.
Carrier sense multiple access with collision avoidance (CSMA/CA) is a protocol used in wireless networks to avoid data collisions caused by multiple devices communicating simultaneously.
When a device is ready to transmit, it listens to its communication channel to check whether it is idle. If so, then the data is transmitted. If the channel is busy, the device waits for a random period of time before checking the channel again. An exponential backoff algorithm can be used to increase the time period for which the device waits with each check of the channel.
While CSMA/CA is effective at eliminating collisions in small networks, it cannot overcome hidden nodes: a problem that arises when the device checking for an idle channel cannot “see” some parts of the network on which communication may be occurring.
To get around the problem of hidden nodes, a protocol called request to send/clear to send (or RTS/CTS) is used. This protocol adds an additional step into the CSMA process. Once the transmitting device has checked whether the channel is idle, it sends a “request to send” message to the server.
If the server is indeed idle, it will respond with a “clear to send” message at which point the transmitting device can begin communication with the server. If no “clear to send” message is received, the server is busy communicating with a hidden node and the transmitting device must wait before starting the CSMA process again.
