PHYS-P 150 Lecture 30: Lecture 30: WiFi, Bluetooth, and Disks
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Wifi operates in radio bands separate from cell phone and broadcast bands: these bands are not regulated as closely compared to cell phone/broadcast bands. Most common wi-fi uses 2450 mhz band: split up into 14 channels, only 1-11 are used in the us, each is 5 mhz wide. As the users increase, the data rate decreases: this is because snr decreases. The farther away you move from a wifi access point, the worse your data rate becomes: this is because you are not receiving as strong of a signal. Designed to do low-power communication from a laptop, headphones, speakers, etc. Two types: low energy, band is split into 40 channels, designed for audio (especially on mobile devices, basic rate/enhanced data rate, band is split into 79 channels, can be used to transfer relatively small files. Makes use of spread spectrum technique known as frequency hopping: used to reduce interference or to encrypt data.
