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
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(Eq. 64)
where a2+b2=1 and xand yiare independent Gaussian distributed variables, both with zero mean and variance σ2.yi and yjfor are independent as well.
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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
Image Modified
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(Eq. 65)
In most LTE studies, Image Removed
is assumed [10]. For
cellular 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.
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