Signal-to-interference-plus-noise ratio

In information theory and telecommunication engineering, the signal-to-interference-plus-noise ratio (SINR[1]) (also known as the signal-to-noise-plus-interference ratio (SNIR)[2]) is a quantity used to give theoretical upper bounds on channel capacity (or the rate of information transfer) in wireless communication systems such as networks.

If the power of noise term is zero, then the SINR reduces to the signal-to-interference ratio (SIR).

[3] The complexity and randomness of certain types of wireless networks and signal propagation has motivated the use of stochastic geometry models in order to model the SINR, particularly for cellular or mobile phone networks.

Typically, the energy of a signal fades with distance, which is referred to as a path loss in wireless networks.

In a wireless network one has to take other factors into account (e.g. the background noise, interfering strength of other simultaneous transmission).

In particular, for a receiver located at some point x in space (usually, on the plane), then its corresponding SINR given by where P is the power of the incoming signal of interest, I is the interference power of the other (interfering) signals in the network, and N is some noise term, which may be a constant or random.

Like other ratios in electronic engineering and related fields, the SINR is often expressed in decibels or dB.

Under the simple power-law path-loss model becomes In wireless networks, the factors that contribute to the SINR are often random (or appear random) including the signal propagation and the positioning of network transmitters and receivers.

Consequently, in recent years this has motivated research in developing tractable stochastic geometry models in order to estimate the SINR in wireless networks.

The related field of continuum percolation theory has also been used to derive bounds on the SINR in wireless networks.