Average Rate of Downlink Heterogeneous Cellular Networks over Generalized Fading Channels: A Stochastic Geometry Approach

In this paper, we introduce an analytical framework to compute the average\nrate of downlink heterogeneous cellular networks. The framework leverages\nrecent application of stochastic geometry to other-cell interference modeling\nand analysis. The heterogeneous cellular network is modeled as the\nsuperposition of many tiers of Base Stations (BSs) having different transmit\npower, density, path-loss exponent, fading parameters and distribution, and\nunequal biasing for flexible tier association. A long-term averaged maximum\nbiased-received-power tier association is considered. The positions of the BSs\nin each tier are modeled as points of an independent Poisson Point Process\n(PPP). Under these assumptions, we introduce a new analytical methodology to\nevaluate the average rate, which avoids the computation of the Coverage\nProbability (Pcov) and needs only the Moment Generating Function (MGF) of the\naggregate interference at the probe mobile terminal. The distinguishable\ncharacteristic of our analytical methodology consists in providing a tractable\nand numerically efficient framework that is applicable to general fading\ndistributions, including composite fading channels with small- and mid-scale\nfluctuations. In addition, our method can efficiently handle correlated\nLog-Normal shadowing with little increase of the computational complexity. The\nproposed MGF-based approach needs the computation of either a single or a\ntwo-fold numerical integral, thus reducing the complexity of Pcov-based\nframeworks, which require, for general fading distributions, the computation of\na four-fold integral.\n