This letter analyses the effective capacity of communications system
using unified models. In order to obtain a simple closed-form
mathematically tractable expression, two different unified approximate
models have been used. The mixture gamma (MG) distribution which
is highly accurate approximation approach has been firstly employed
to represent the signal-to-noise-ratio (SNR) of fading channel. In the
second approach, the mixture of Gaussian (MoG) distribution which is
another unified representation approach has been utilised. A comparison
between the simulated and numerical results using both distributions
over composite α − η − µ/gamma fading channels has been provided
