Coverage area The coverage area U() is defined as the percentage of useful service area (i.e., the percentage of area where the received signal is equal to or greater than ), given a known likelihood of coverage at the cell boundary (boundary coverage, i.e., the fraction of the time the received signal power Pr is to exceed the threshold  at the boundary R). The formula for the boundary coverage is P½PrðRÞ >  ¼

1 2



1 2

erf

  fPt  ½PLðd0Þ þ 10n logðR=d0Þg

 ffiffiffi 2 p



:

If we let a ¼ ½  Pt þ PLðd0Þ þ 10 logðR=d0Þ= ffiffiffi 2 p

and b ¼ ð10n log eÞ= ffiffiffi 2 p

, the coverage area is UðÞ ¼

1 2

1  erfðaÞ þ exp 1  2ab b2



1  erf 1  ab b

 


:

Plot the curves of U() from  / n¼0 to  / n¼8 for boundary coverage of 0.5, 0.55, . . . , 0.95. Comment on the plot.