TDM, FDM and CDMA share channels among users.
Multiplexing shares a channel among users: FDM (frequency slots), TDM (time slots), CDM (spreading codes), WDM (optical wavelengths), SDM (space/MIMO) and statistical multiplexing. Multiple access in cellular: FDMA, TDMA, CDMA, OFDMA. Guard bands and synchronisation avoid interference.
DSL and cable TV use FDM; optical networks use WDM.
Multiplexing shares one channel among many users or signals, which is why a single fibre or radio band can serve so many people.
TDM, FDM and CDMA share channels among users.
Multiplexing shares one channel among many users or signals, which is why a single fibre or radio band can serve so many people.
Each user gets the whole channel for short time slots in turn, which suits digital data streams.
Users share the same band and frequency at the same time, separated by unique spreading codes.
Typical applications include sending several sensor streams over one cable with time division, sharing a radio band among many mobile users with CDMA and carrying many TV channels in one cable with frequency division.
Study "Modern codes" first (topic 86 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.
Orthogonality. Throughput efficiency. Statistical gain.
DSL and cable TV use FDM; optical networks use WDM.
The next topic is "OFDM", which builds directly on this one.
It is classed as Advanced in Signals, Control & Comms (topic 87 of 101). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Signals, Control & Comms.
Want to practise? Open the interactive course for quick checks, quizzes, simulations and progress tracking.