Second-tier approximation for SIR. Modify the SIR analysis of first tier to include a second tier of interferers and compare the resulting SIR with the one derived for N = 7. Consider all 12 second tier interferers, 6 at distance 2D and 6 at distance √3D. (Use the improved approximations for distances for the first tier only. Assume a path loss exponent of n = 4.)