An analog wireless communication system needs to transmit $5$ different signals at the same time, using frequency multiplexing. Between each of the channels it is necessary to leave a guard band $20$kHz$,$ as well as at the end and beginning of the available band. Furthermore, the $5$ message signals do not have all the same bandwidth: $2$ signals have a bandwidth of $20$kHz$,2$ signals have a bandwidth of $40$kHz and $1$ signal have a bandwidth of $60$kHz$.$ You can use modulators like DSB$-$SC$,$ SSB or QAM. a$)$ Determine the bandwidth required if DSB$-$SC modulation is used on all signals. b$)$ Redo it considering SSB modulation for all signals. What characteristic do message signals must they have for this solution to be viable in practice? c$)$ What is the minimum total bandwidth required assuming you do not need to use the same type of modulation for all signals?