Wifi

WiFi, technically specified in the IEEE 802.11 set of standards, is one of the most widely deployed wireless standards in the world. Chance are the device you are using to read this article has is WiFi enabled. WiFi is a straightforward extension of Ethernet, with some slight adaptations for using radio instead of copper wire as the communication channel. Like Ethernet, WiFi has no central process that controls which device is allowed to transmit data at any point in time. Instead, each device decides on its own, and all devices must work together to guarantee good shared channel performance. With Ethernet, the protocol senses when the communication channel is busy and waits until it is free before sending data (carrier sensing). Ethernet also adds a collision detection protocol as an optimization. If a collision is detected, nodes stop sending data and use a randomized backoff algorithm to decide when to begin sending again. Together, these algorithms form the carrier-sense multiple access with collision detection algorithm (CSMA/CD). WiFi uses a similar strategy to Ethernet, but is restricted by the communication channel — there is no reliable way to detect collisions using radio waves. Therefore, instead of collision detection, WiFi uses a collision avoidance strategy defined by the carrier-sense multiple access with collision avoidance algorithm (CSMA/CA). ...