9.11 Pathloss Correlation

The concept of a simple correlation model for shadow fading has been widely adopted in LTE co-existence studies mostly employed in uplink case. The propagation attenuation is modelled as the product of the path loss and the shadow fading. The shadow fading is well approximated by a log-normal distribution. Let z denotes shadow fading in dB with zero mean and variance σ 2 . Then the shadow fading of path from one UE to the i-th BS is expressed as 
     (Eq. 64) 
   
 where  a 2 +b 2 =1 and x and y i are independent Gaussian distributed variables, both with zero mean and variance σ 2 . y i and y j for are independent as well. 
 Figure 207 presents how to set-up the pathloss correlation in SEAMCAT (only available for OFDMA ). The panel is similar for the OFDMA DL and UL . 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Figure 207: Illustration of the pathloss correlation – input parameters 
   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Figure 208: Illustration of the pathloss correlation principle 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   
 Thus, the correlation coefficient of the shadow fading from one UE to two different BSs, i.e., the i-th and j-th BS , is 
 (Eq. 65) 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   
  In most LTE studies,   is assumed ‎[10]. For cellurar systems with three-sector antennas, the shadowing correlation between sites (equivalent to BS in Omni antenna system) is of 0.5 and correlation between sectors of the same site is consequently of 1.