I was told that a WiFi AP re-modulates its radio signal in order to enable it to better go through obstacles and noisy places, reaching more distant client's transceivers this way. Basically, the receiver tells the transmitter to slow down to get the data more clearly. As a result the data rate slows down too. what exactly of a radio wave is re-modulated? Frequency, amplitude, or what? Could anyone also graphically represent a radio wave before it gets remodulated and after, when it carries less data?

  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer. – Ron Maupin Dec 15 '19 at 20:02

I think you are talking about beamforming - it's not about modulating the signal itself but controlling the phases transmitted by the different parts of the antenna array. Ideally, the different phases add up to a maximum in the exact position of the receiver.

Another method for the radio to achieve a greater effective distance is to lower the transmission rate, so that even a weak signal is still decipherable. The slower rate may also use another modulation method but not necessarily.

Most 802.11 modes use quadrature amplitude modulation (QAM) which can get quite complex when modelled in practice.

  • "to achieve a greater effective distance is to lower the transmission rate". But lowering the transmission rate is still transmit data over the same radio wave with the same features? Just less data on the same wave? – jeysmith Nov 17 '19 at 9:40
  • Signal amplitude drops with distance squared plus attenuation by obstacles. Lower amplitude means lower signal-to-noise ratio. Lower SNR means you can only get a lower data rate across. – Zac67 Nov 17 '19 at 9:59

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