15 B. Derivation for the Downlink Interference: The downlink interference X$_{l}$ considering a single interfering cell l can be written as: where χ$_{l}$ is the interfering statistics from the l th neighboring BS, and ¯ r$_{l}$ is the distance of l th interfering BS from the scheduled mobile receiver. At this point, it is important to highlight that for a given r$_{k}$ and θ$_{i}$ of a scheduled mobile user in the cell of interest, the distance of all interfering BSs can be calculated using cosine law which is not the same as in the uplink, where all ˜ r$_{l}$ are independent from one another . Therefore, conditioned on the location of the mobile receiver, the distribution of the downlink cumulative ICI, i.e., Y | r$_{k}$, θ$_{i}$ , is simply a weighted sum of the distribution of the interfering channel statistics χ . More precisely and by using the symmetry of the grid model the PDF of the cumulative ICI ( Y = ∑ L l $_{=1}$X$_{l}$ ) can be given as: and the distance of all interferers can be determined using cosine law as follows: where Given the distance of the interferers, the conditional MGF of the cumulative interference can be calculated as follows: Finally the MGF of the cumulative ICI can be calculated as follows: The expression for the MGF of the cumulative ICI in (46) is general for any kind of composite channel fading models. The explicit expressions for three above discussed practical fading models can also be obtained in a straightforward manner. f$_{Y}$ ( y ) = r$_{K}$ ∑ r$_{k}$ = r 1 2 π ∑ θ$_{i}$ =0 P ( r$_{sel}$ = r$_{i,k}$ ) f$_{Y}$$_{|}$$_{r}$$_{k}$$_{,θ}$$_{i}$ ( y | r$_{k}$, θ$_{i}$ ) (42) Y | r$_{k}$, θ$_{i}$ = L ∑ l =1 ¯ r − β l χ$_{l}$ (43) ¯ r$_{l}$ = √ D 2 + r 2 k − 2 r$_{k}$D cos(( l − 1) π/ 3 + π/ 6 − θ$_{i}$ ) ∀ l = 1 , ...L (44) M$_{Y}$$_{|}$$_{r}$$_{k}$$_{,θ}$$_{i}$ ( t ) = L ∏ l =1 M$_{χ}$ (¯ r − β l t ) (45) M$_{Y}$ ( t ) = r$_{K}$ ∑ r$_{k}$ = r 1 2 π ∑ θ$_{i}$ =0 P ( r$_{sel}$ = r$_{i,k}$ ) L ∏ l =1 M$_{χ}$ (¯ r − β l t ) (46) X$_{l}$ = ¯ r − β l χ$_{l}$ (41)