Channel Quality Estimation Index (CQEI): A Long-Term Performance Metric for Fading Channels and an Application in EGC Receivers

Low Complexity Amplify and Forward Relaying without Channel Amplitude Estimation

“…Due to the similarities of the DEGC receiver with the classic EGC one, our relay selection method is similar to that presented in [14], where a long term statistical criterion was used for the rejection of the weakest diversity branches in EGC receivers. It should be noted that although a long term criterion could theoretically involve any order of the SNR statistics, we utilize only the first and second moments of the combined SNR, which is a more practical realization of such a criterion.…”

“…Such method is widely used in several scientific fields, serving as an alternative means of approximating series similar to that in (14) where practically only few coefficients are known and the series converges too slowly or diverges [12], [13]. A Padé approximant is a rational function approximation to M γout (s), namely P [A/B] (s), whose nominator and denominator are of order A and B, respectively, and whose power expansion is identical with the A + B order expansion of M γout (s) , i.e.,…”

“…Extensive simulation experiments showed that an appropriate metric for the case of DEGC could be a modified version of the Channel Quality Estimation Index (CQEI) proposed in [14]. The latter metric was proposed for quantifying the quality of point-to-point communications, where no relaying takes place.…”

“…We note that similarly to [14], GCQEI represents a minimization criterion. Through the parameter ν, GCQEI offers the possibility to control the relative sensitivity of this metric to the SNR variance around its mean value, compared to the mean value itself.…”

The N∗Fisher-Snedecor F Cascaded Fading Model

“…The channel quality estimation index (CQEI) is an effective measure that provides insights on the amount of fading of at certain SNR values. It is defined as the ratio of the variance of the instantaneous received SNR γ to the cubed mean of the received SNR γ [29], namely…”