Grades 6–8 · Systems
How does Wi-Fi carry a message without a cable?
A Wi-Fi connection replaces a short network cable with a radio link. Your device divides data into messages called frames. Its radio changes a rapidly oscillating signal in controlled ways to represent the frame’s bits. An antenna launches electromagnetic waves, and a receiving antenna converts a tiny part of that energy into an electrical signal.
In the diagramWi-Fi carries addressed frames by radioLocal radio link ≠ the whole internet connectionDeviceAccess pointLocalnetworkRadio linkAttempt 1Not deliveredAttempt 2Attempt 3Delivered500 bytes delivered • 6 ms of model airtimePayload only: 0.67 Mbit/s • timing is invented
The access point decodes the signal and connects the wireless device with the rest of the local network. Many home boxes combine this role with routing and other jobs. Wi-Fi can link local devices even when the separate connection to the internet is unavailable.
A radio message can be spoiled by interference or a weak signal. Delivery checks allow frames to be sent again. In the simplified example, one successful 500-byte payload needs three attempts of 2 milliseconds each. The same useful data now occupies 6 milliseconds rather than 2. Real timing includes many additional exchanges, and other devices share the radio channel. The waves in the drawing represent a communication link, not little envelopes flying through the air.
About this explanation
Starting knowledge: Recognize that digital information can be divided into small messages.
Sources
- Cisco — What Is Wi-Fi?
- Cisco — What is a wireless access point?