Cellular Systems Cellular Concepts The cellular concept was a ...

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EE5401 Cellular Mobile Communications EE5401 Cellular Mobile Communications - More accurate SIR can be obtained by computing the actual distance. - Aproximation in distance has been made on the 2 nd tier onwards. - Our computation of outage only based on path loss. For more accurate modeling, shadowing and fast fading need to be taken into consideration. This will not be covered in this course. Institute for Infocomm Research 57 National University of Singapore Institute for Infocomm Research 58 National University of Singapore
EE5401 Cellular Mobile Communications EE5401 Cellular Mobile Communications Coverage Problems Revision: - Recall that the mean measured value, ⎛ d ⎞ PL( d) dB = PL( d0) dB + 10n log ⎜ ⎟ or ⎝ d0 ⎠ P r ( d) dB = PtdB − PL( d) dB [ P ( γ ] β ( γ ) = P r R) > - cell boundary coverage, β ( γ ) ∞ = ∫ γ 1 2πσ X dB ⎛ ⎞ ⎜γ − P = r ( R) Q ⎟ ⎜ ⎟ ⎝ σ X dB ⎠ ⎡ 2⎤ ⎢ 1 ⎛ ⎞ ⎜ X − − dB Pr ( R) exp ⎟ ⎥dX ⎢ ⎜ ⎟ ⎥ dB 2 ⎢⎣ ⎝ σ X dB ⎠ ⎥⎦ where Q(x) is the standard normal distribution. • must know how to use the table. - Measurement shows that at any value of d, the path loss PL (d) at a particular location is random and distributed log-normally (normal in dB) about this mean value. Pr ( d) dB = Pr ( d) dB + X σ where X σ is a zero-mean Gaussian distributed random variable (in dB) with standard deviation σ (in dB). Boundary coverage Cell coverage • Proportion of locations within the area defined by the cell radius R, receiving a signal above the threshold γ. 1 U ( γ ) = ∫ P[ Pr ( r) > γ ] dA A A 1 R 2π ⎛ P r ⎞ Q⎜γ − r ( ) = ∫ ∫ ⎟ ⋅ rdr ⋅ dθ 2 πR ⎜ X ⎟ 0 0 ⎝ σ dB ⎠ 2 R ⎛ P r ⎞ Q⎜γ − = r ( ) ∫ ⎟ ⋅ rdr R ⎜ X ⎟ 0 ⎝ σ dB ⎠ • Therefore, there will be a proportion of locations at distance R (cell radius) where a terminal would experience a received signal above a threshold γ. (γ is usually the receiver sensitivity) The solution is given in the Rappaport p.107 (1 st edition). Institute for Infocomm Research 59 National University of Singapore Institute for Infocomm Research 60 National University of Singapore
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