Self-organized time-division multiple access (STDMA or SOTDMA) is a channel access method designed by Håkan Lans, based on time-division multiplexing. The term "self-organized" describes the manner in which time slots are assigned to users.

Time-division multiple access Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, ...

(TDMA) divides a channel into frames, which furthermore are subdivided into a vast number of time slots. Users transmit in rapid succession, one after the other, each using their own time slot. One of the drawbacks of TDMA is that it requires a central station for slot assignment and time synchronization. STDMA proposes a method for assigning slots without the involvement of a central station. Time synchronization is usually taken care of using

Coordinated Universal Time Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communicat ...

(UTC). Slot assignment is handled by each transmitter broadcasting its next slot reservation as part of the message during its current slot. STDMA is in use by the

Automatic Identification System The automatic identification system (AIS) is an automatic tracking system that uses transceivers on ships and is used by vessel traffic services (VTS). When satellites are used to receive AIS signatures, the term ''Satellite-AIS'' (S-AIS) is ...

(AIS), a standard marine short-range coastal tracking system, and is the base of the

International Civil Aviation Organization The International Civil Aviation Organization (ICAO ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international sch ...

VHF Data Link Mode 4. While the method was patented, a

US patent Under United States law, a patent is a right granted to the inventor of a (1) process, machine, article of manufacture, or composition of matter, (2) that is new, useful, and non-obvious. A patent is the right to exclude others, for a limit ...

ex-parte

reexamination In United States patent law, a reexamination is a process whereby anyone—third party or inventor—can have a U.S. patent reexamined by a patent examiner to verify that the subject matter it claims is patentable. To have a patent reexamined, ...

certificate was issued in 2010 canceling all claims.USPTO ex-parte reexamination certificate 7428, issued on March 30, 2010.
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References

External links

GP&C Systems International AB
Holding company of STDMA patent rights in Europe {{Channel access methods Maritime communication