Among TDM and FDM which one is noisy?

tdm: total available time is divided into several user

eg: telephone system

fdm: total frequency bands are divided into several users

eg : television broad casting

wdm: total wave lengnth is divided in to number of users

eg: optical networking

These are particular one line definitions of tdm, fdm and wdm but you should realize that there is no difference in fdm and wdm, they are different terms talked in context of radio waves and optical fiber accordingly. As both light waves and radio waves are electro magnetic waves there speed is same so if you are dividing frequency or wave length both are leading to same.