Hata Model is applied for GSM Link Budget,here i write about its formula and Cell Size Estimation.
Hata´S Empirical Formula
PL = 69.55 +26.6log10fc - 13.82log10hb + (44.9 – 6.55log10hb)log10R – a(hm) -CF
fc – Frequency in MHZ
hb – Transmitter antenna height
hm – Receiver antenna height
R – Radius in Km
a(hm) is the correction factor for effective mobile antenna height
Solving backwards the cell radius is given by
log10R = MAPL +CF – 69.55 +26.6log10fc + 13.82log10hb + a(hm) / (44.9 – 6.55log10hb)
Cell Size/Count Estimation
- Once the Maximum allowable path loss is known, the achievable cell size can be evaluated.
- Cell radius is calculated using MAPL and Hata’s empirical formula.
- Cell radius is the distance from base station where the path loss equals MAPL. Beyond this radius, the signal is too weak to be acceptable.
- Each area has a different correction factor.
- Also the coverage objectives are usually different for Urban, Suburban and Rural areas.
- Therefore MAPL has to be calculated for each area and then cell size determined separately.
- Once the cell radius is calculated, cell count estimates can be made.
- Once the cell radius for each area is calculated, then the minimum number of cells required to provide coverage can be determined.
- For each area
A = 2.6R2
- R – radius of cell
- A – Area of the corresponding hexagon.
- Cell count = Urban Area(Km2) + Suburban area(Km2) + RuralArea(Km2)
- Cell Count = Aurban(Km2) + Asuburban(Km2) + Arural(Km2)