Ergodic capacity of distributed antenna systems over Shadowed Nakagami-m fading Channels

This paper focuses on the downlink ergodic capacity of distributed antenna systems (DAS) over Shadowed Nakagamim fading Channels. A composite channel is established, which includes both large-scale fading and small-scale fading. Then, the probability density function (PDF) of the output signal-to-noise ratio (SNR) is derived. To facilitate the analysis, the distribution of the output SNR is approximated by a lognormal distribution. After that, by using Gauss-Hermite integration, an approximate analytical expression of the capacity for a mobile station (MS) over a given place is derived. Furthermore, by employing the composite Simpson´s rule, a closed-form expression of the ergodic capacity is obtained. Numerical results show that the derived analytical expression of ergodic capacity can provide very well approximation to the simulation results.