In Frequency Division Multiplexing we provide one channel to one user.
Example like BandWidth of user1's voice is 200Khz. I provide one channel of 200KHz in FDM for uplink as shown in the figure. Now I will provide another 200KHz Bandwidth(channel 2) for user2's voice. Similarly for user3. I will be having a guard band of 100 Hz for this.
Now What I understand about OFDM is that channel1 will be orthogonal to all other channels. Also, we divide channel 1 into orthogonal sub-carriers with bandwidth less than 200KHz.
Am I correct? If yes then will there be no ISI as my required Bandwidth is 200KHz.