5 Types of Multiplexing Techniques

Introduction : Multiplexing is a technique in which multiple signals share common medium efficiently. It is applied in copper, fiber and wireless systems. The most common five techniques are FDM, TDM, WDM, CDM and SDM. Each technique operates on different dimension i.e. frequency, time, wavelength, code and space respectively. These techniques help to maximize channel utilization and meets the requirements of modern communication systems.

FDM

• FDM stands for Frequency Division Multiplexing
• It divides the available bandwidth into distinct and non-overlapping frequency bands. Each of these bands carries separate data for transmission.
• Pros : Easy simultaneous transmission
• Cons : Guard bands are needed between bands to avoid interference
• Applications : DSL, radio broadcasting, Television broadcasting, cable networks

TDM

• TDM stands for Time Division Multiplexing
• It allocates unique time slots to different data symbols in repeating sequence.
• Pros : Efficient utilization of frequency resources as same band is being used by multiple time slots.
• Cons : Wastage of time resources if slots are not used
• Applications :T1/E1 digital telephony, synchronous optical networks

Fig.1 TDM and FDM

WDM

• WDM stands for Wavelength Division Multiplexing
• It is optical variant of FDM technique, which uses different light wavelengths in a single optical fiber.
• Pros : Massive boost in the capacity
• Cons : Costly and complex to align wavelengths accurately
• Applications : CWDM and DWDM systems used in fiber optic communication

CDM

• CDM stands for Code Division Multiplexing
• This technique allocates unique codes to each data signal. It allows simultaneous transmission over same frequency. Signals are separated at the receiver using code correlation.
• Pros : Highly secure, resistant to interference
• Cons : Complex encoding/decoding
• Applications : CDMA networks, GPS, spread spectrum communications

SDM

• SDM stands for Space Division Multiplexing
• It uses multiple physical paths such as separate fibers or multiple antenna elements (in MIMO) to carry parallel data channels.
• Pros : Enhance capacity in wireless/fiber networks
• Cons : Requires complex hardware and precise alignment
• Applications : Multi-core fiber, MIMO

Conclusion :

Choosing the right multiplexing method depends on key factors such as medium type, application requirements, bandwidth, complexity, performance and scalability. The 5 multiplexing techniques mentioned exploit different signal dimensions to enhance capacity and efficiency of communication channels.