Single-input single-output system

Not to be confused with Single-entry single-exit.

Understanding of SISO, SIMO, MISO and MIMO in radio systems

SISO is an acronym for single-input and single-output system. In control engineering it usually refers to a simple single variable control system with one input and one output. In radio it is the use of only one antenna both in the transmitter and receiver.

SISO systems are typically less complex than multiple-input multiple-output (MIMO) systems. Usually, it is also easier to make order of magnitude or trending predictions "on the fly" or "back of the envelope". MIMO systems have too many interactions for most of us to trace through them quickly, thoroughly, and effectively in our heads.

Frequency domain techniques for analysis and controller design dominate SISO control system theory. Bode, Nyquist, Nichols, and root locus are the usual tools for SISO system analysis. Controllers can be designed through the polynomial design, root locus design methods to name just 2 of the more popular. Often SISO controllers will be PI, PID, or lead-lag.

See also

• Control theory
• Multiple-input multiple-output

References

• Partington, Jonathan R. (2004), Linear operators and linear systems, London Mathematical Society Student Texts, Cambridge University Press, p. 75, ISBN 0-521-54619-2