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Do wireless networks employ both Carrier Sense Multiple Access and Orthogonal Frequency Division Multiplexing? If so, what are their corresponding roles? I'm not a professional and I am confused as to which of them makes P2MP communication possible. I always thought WLANs use CSMA to allow different nodes to communicate to the same access point on the same channel, but here I am reading about how every 802.11 standard uses OFDM as its access technology (except 802.11b which uses DSSS instead), allowing multiple devices to communicate with the same AP at the same time.

Is this the right place for PHY-related questions?

EDIT: changed TDM to CSMA to be more accurate.

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Finally found out that in Wifi, CSMA is the one used to allow Multiple Access. To be exact, IEEE 802.11 releases use CSMA/CA (Collision Avoidance) instead of CSMA/CD (Collision Detection) which is used in wired networks.

OFDM, on the other hand, is just an advanced digital modulation scheme which divides the data stream being exchanged between the node and the AP to multiple individual streams of lower rate and transmits them on different, closely-spaced carrier frequencies simultaneously (multiplexing). Making the signal more robust against error--thus allowing higher data rates--is what OFDM does in a nutshell.

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