c. What should be the cluster size if assuming that 6 cells are close enough to create significant interference and they are approximately equidistant from the desired Base Station (BS)? Assume the Advanced Mobile Phone Systems (AMPS) use Frequency Modulation (FM) and path loss factor is 4 and 25 kHz channels, and it indicates that sufficient voice quality is provided when Signal to Interference Ratio (S/I) is greater than or equal to 15 dB.