Quadrature-division multiple access (QDMA) is a radio protocol. The term combines two standard terms in

telecommunications Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...

CDMA Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communicatio ...

and

QPSK Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency carrier wave. The modulation is accomplished by varying the sine and cosine inputs at a precise time. It is ...

Applications

QDMA is used for

local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, campus, or building, and has its network equipment and interconnects locally managed. LANs facilitate the distribution of da ...

s, usually wireless short-range such as

WiMax Worldwide Interoperability for Microwave Access (WiMAX) is a family of wireless broadband communication standards based on the IEEE 802.16 set of standards, which provide physical layer (PHY) and media access control (MAC) options. The WiMA ...

. CDMA and QDMA are especially suitable for modern communications, for example, the transmission of short messages such as

SMS Short Message Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile phones exchange short text messages, t ...

or MMS; communication when in motion (from cars, trains, etc.); the establishment of unplanned links.

Benefits over TDMA and FDMA

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.

Applications

Benefits over TDMA and FDMA

References

Further reading