QUESTION

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# 1. (25 points total) Suppose a cellular system will be deployed along a major highway. Figure 1 depicts the possible layout of the base stations and their coverage areas, cells with same letter use the same set of frequencies. Assume received power at reference distance $d_{0}$ is $P_{0}$; and all the base stations radiate at the same power level. Figure 1: Cellular system layout (a) (8 points) Please formulate the worst case co-channel signal to interference ratio (C-SIR) with respect to propagation loss factor $(n)$ including first and second tier interferers? (Hint: you can assume width of the highway is much smaller than $R$ and negligible in your calculations.) (b) (7 points) If the system can operate at C-SIR $=18 \mathrm{~dB}$, does this system work with 2-Cell layout as shown in Figure 1 with loss factor $3(n=3)$ ? Second Tier Intererer Figure 2: Cellular system layout with sectoring (note: Sectoring of B cells are not shown.) (c) (5 points) If you sector the cells 180 degree antennas, depicted in Figure 1b, what would be C-SIR for propagation loss factor $(n)$ ? (d) (5 points) Does the sectorized system satisfies the requirement set by the manufacturer that is C-SIR $>18 \mathrm{~dB}$ for $n=3$ ?  