Quality assessment for pre-detection diversity switching

In cellular mobile systems the on-line assessment of a radio link performance is normally associated with measurements of the received signal power, and is taken before signal demodulation. It determines the thresholds for handover policies, transmitting power control, diversity switching schemes, and other operations. However, a large received signal power does not necessarily mean "good quality" when it comes to considering radio links corrupted by cochannel interference, multipath propagation and background noise. In such cases, a better parameter that can be used to assess the signal quality is the signal-to-interference-plus-noise power ratio (SINR). Although this quality factor parameter is well-known in the literature, little has been written about how to measure it in a practical context. This article presents a method for the SINR estimation applied to a system using the Digital European Cordless Telecommunications (DECT) specification, but it can also be used by any other system employing constant modulus signals.