Alice wants to send a message X to Bob over a frequency band with the bandwidth B$.$ Charlie

wants to over$-$listen the talk between Alice and Bob. The distance between Alice and Bob is $1$

km$,$ and the distance between Alice and Charlie is $2$ km$.$ The amount of information bits that

Alice wants to send is $1$k bits. The signal transmit power of Alice$$s communication device is

limited to $50$ mWatt. The noise power spectral density $($N$0)$ is $3$:$98\backslash$times $10-15$ mW$/$KHz $($Noise

power $=$ B x N$0)$ The communication is subject to two conditions:

c$1)$ Alice wants to send the information reliably to Bob within $10$ ms$.$

c$2)$ Alice does not want Charlie to decode the information.

What is the range of B that Alice should use to transmit X$?$