System Level Modeling and Optimization of the LTE Downlink

3. Physical Layer Modeling and LTE System Level Simulationy pos [m]shadow fading [dB]10008006004002000−200−400−600−800−1000−1000 −500 0 500 1000x pos [m]403020100−10−20−30−40cell SINR [dB]−1000 −500 0 500 1000x pos [m]20151050−5Figure 3.9: Left: shadow fading map in dB (µ = 0 dB, σ = 10 dB). Zommed: detail of theintroduced spatial correlation. Right: resulting cell wideband SINR in dB.employing the 12-neighbor correlation matrix in Appendix B and an inter-site correlationof 0.5. Despite the introduced spatial correlation, the overall log-hormaldistribution of each map is not altered. Figure 3.10 depicts the overlapped pdfs ofeach of the 19 shadow fading maps (in black), compared to the analytical pdf. Theright plot depicts the inter-site correlation matrix, with (excluding the diagonal) amean value of 0.5009 dB and a standard deviation of the mean values of 0.0042 dB.0.050.040.030.020.01Normal distributionCorrelated shadow fading maps0−60 −40 −20 0 20 40 60shadow fading [dB]246810121416182 4 6 8 10 12 14 16 1810.950.90.850.80.750.70.650.60.550.5Figure 3.10: Left: comparison of the pdf of the obtained shadow fading maps in dB witha normal distribution with µ = 0 dB, σ = 10 dB. Right: inter-site correlationmatrix.3.1.2. Link Performance ModelThe channel quality measure output by the link quality model serves as input to thelink performance model. As detailed in Section 3.1.1 and depicted in Figure 3.5, asubset of the subcarrier post-equalization SINRs parametrize the channel conditionson a per-spatial-layer basis.For the RB set in which the UE is scheduled (if scheduled), the link performance38