Quadrature-division multiple access
{{more footnotes|date=July 2010}}
Quadrature-division multiple access (QDMA) is a radio protocol.{{cite book|last=Held|first=Gilbert|title=Wireless mesh networks|year=2005|publisher=CRC Press|isbn=978-0-8493-2960-9|pages=44|url=https://books.google.com/books?id=FdHevsDK3mEC&pg=PA44}} The term combines two standard terms in telecommunications, CDMA and QPSK.
Applications
QDMA is used for local area networks, usually wireless short-range such as WiMax. CDMA and QDMA are especially suitable for modern communications, for example, the transmission of short messages such as SMS or MMS; communication when in motion (from cars, trains, etc.); the establishment of unplanned links.
Benefits over TDMA and FDMA
{{Unreferenced section|date=July 2010}}
The traditional TDMA and FDMA require a lot of overhead to set a link parameter with a new user, or to detect that a user left and their allocation is free to be allocated to another. In CDMA or QDMA, a new user is simply allocated a new code and is ready to go. It may impose a slight load on the spectrum, but the system is so devised as to absorb a controlled measure of collisions and continue operations at a high level of quality of service.
References
{{Reflist}}
Further reading
- John G. Proakis, Digital Communications, Third Edition, McGraw-Hill, {{ISBN|0-07-051726-6}}
- Ulrich L. Rohde, Jerry Whitaker, T. T. N. Bucher, Communications Receivers, Second Edition, McGraw-Hill, {{ISBN|0-07-053608-2}}
Category:Channel access methods
{{radio-comm-stub}}