Editing Channel access method (section)

===Frequency-division multiple access===
The [[frequency-division multiple access]] (FDMA) channel-access scheme is the most standard analog system, based on the [[frequency-division multiplexing]] (FDM) scheme, which provides different frequency bands to different data streams.  In the FDMA case, the frequency bands are allocated to different nodes or devices. An example of FDMA systems was the first-generation [[1G]] cell-phone systems, where each phone call was assigned to a specific uplink frequency channel and another downlink frequency channel. Each message signal (each phone call) is [[modulated]] on a specific [[carrier frequency]].

A related technique is wavelength division multiple access (WDMA), based on [[wavelength-division multiplexing]] (WDM), where different data streams get different colors in fiber-optical communications. In the WDMA case, different network nodes in a bus or hub network get a different color.<ref>{{Cite web|url=https://www.abcofnetworks.com/2019/02/Multiple-Access-Techniques-in-communication-FDMA-TDMA-CDMA.html|title=Multiple Access Techniques in communication: FDMA, TDMA, CDMA|last=Sadique|first=Abubaker|archive-url=https://web.archive.org/web/20191009145423/https://www.abcofnetworks.com/2019/02/Multiple-Access-Techniques-in-communication-FDMA-TDMA-CDMA.html|archive-date=2019-10-09}}</ref>

An advanced form of FDMA is the [[orthogonal frequency-division multiple access]] (OFDMA) scheme, for example, used in [[4G]] cellular communication systems. In OFDMA, each node may use several sub-carriers, making it possible to provide different quality of service (different data rates) to different users. The assignment of sub-carriers to users may be changed dynamically, based on the current radio channel conditions and traffic load. [[Single-carrier FDMA]] (SC-FDMA), a.k.a. linearly-precoded OFDMA (LP-OFDMA), is based on single-carrier frequency-domain-equalization (SC-FDE).