Homework 6 Due Friday, Oct. 5, 2018 1/1
6.1 For a N = 3 reuse pattern, what is the improvement in the worst-case uplink S/I with 60°
sectoring (as opposed to the omni case)? If the omni cell has 60 channels and you want a
PB (GOS) of 2%, what is the reduction in the offered traffic that can be handled per cell
after sectoring?
6.2 You have an N = 7 reuse pattern, as shown at left. The center “A” cell is very busy so
you decide to split it as shown at right. What will the worst-case downlink S/I be in each
of the seven new small cells? Assume a propagation exponent n = 3.5 and that
basestation transmitted power in the small cells is reduced so that the signal level at the
cell radius is same as in the large cells. (Hint: estimate the downlink interference
graphically by measuring distances on the reuse pattern.)
6.3 Consider the uplink in an N = 4 reuse pattern with 60° sectoring. With mobiles placed in
the worst-case scenario as in text Fig. 16.6, what level will S/I exceed 90% of the time if
the cell radius is 1km and propagation is described by X r PR dBm ? +? = ? ? 1km , 90 30log
where X is a zero-mean, Gaussian random variable with σ = 8dB.
6.4 At 1900 MHz, how much power must be radiated isotropically so that at a distance of ten meters the power density reaches the FCC limit for general population exposure? What if the antenna gain is 7 dB?
6.5 Write a program in C that prompts the user for: frequency in MHz, antenna gain in dB,
and transmitted power in Watts. The program should then calculate the distances at which
the power density matches the FCC limits for controlled and uncontrolled exposure.
Assume free-space propagation.
6.6 Write a Matlab function called “cluster4(x,y,R)” that, given x,y coordinates and a cell
radius R, draws four hexagon cells on the current figure in the shape of an N=4 cluster
such as in Figure 13.8. It should also label the cell centers with “A” “B” “C” and “D”
labels. The “A” cell should be centered at x,y. The “text” function in Matlab will allow
you to do this. You can use the results of problem 5.6.
EE432: RF Engineering for Telecommunications Washington State University 09/28/18
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