Paranoid schizophrenia is a mental disorder, where the suspicious people are actually not present but it is being felt by the people experiencing or dealing with.

Basically, the person might feel or also experience some kind of the illusions, or suspicious activity, or presence of some other person, where actually there will be nothing like it.

So, we can simply say that in the paranoid schizophrenia issue in the people, the person might experience and feel the presence of someone or some illusions will be there, when actually the similar things are not there.