FDM vs FDMA: Difference and Comparison

Key Takeaways

1. FDM (Frequency Division Multiplexing) and FDMA (Frequency Division Multiple Access) are related but distinct concepts used in telecommunications and wireless communication systems.
2. FDM is a technique that simultaneously transmits multiple signals over a single communication channel by dividing the available frequency spectrum into multiple non-overlapping frequency bands. Each signal is assigned a specific frequency band, which is combined for transmission.
3. On the other hand, FDMA is a multiple-access method that allows multiple users or devices to share a communication channel by allocating distinct frequency bands or channels to each user. It is commonly used in cellular networks, where each mobile device is assigned a unique frequency channel to communicate with the base station.

What is FDM?

Frequency Division Multiplexing, better known as FDM, is a multiplexing technique. We will see its usage in telecommunications and data transmission. The main function of it is taking multiple analog signals with various frequencies and integrating them into a single signal.

Any cable or frequency band carries this compact signal. Even though the frequencies are combined, they do not overlap. As a result, they can be separated at the receiver’s end.

The application of FDM can be seen in cable television, analog radio broadcasting, and telephony, a traditional analog telephone line. Anything that needs to send multiple analog signals simultaneously through a shared communication medium can utilize FDM.

The combined signal is received at the receiver and then separated and sent with their assigned frequencies. Any audio and video output can be sent.

In the past, FDM was used by analog radio stations to broadcast their signals with different frequencies. This way, listeners can tune in to their preferred station.

What is FDMA?

Frequency Division Multiple Access (FDMA) is a multiple access technique in telecommunications and wireless communication systems.

This technique is the key concept in many cellular networks and satellite communication systems. Its principal function is to share a common frequency with multiple devices.

If you dissect the concept of FDMA, here, a frequency gets divided into multiple sub-bands. Each sub-band is issued to an individual device. A central base station governs the allotments.

However, FDMA also has its limitations. It is ideal for voice communication and low-speed data transmission. It was popular with early cellular systems like 1G and 2G networks. It can not put up with the modern high data rate wireless networks.

Difference Between FDM and FDMA

1. The function of an FDM is to combine multiple analog signals into one compact signal, whereas an FDMA assigns exact frequency channels to devices or users.
2. An example of FDM is cable television, where multiple TV channels are transferred simultaneously over a single cable. On the other hand, an example of FDMA is a cellular network where various mobile phones are allotted with specific frequency for communication over data on voice.
3. As per common practice, FDM is utilized for analog signals like voice and video signals. FDMA, on the other hand, can transfer analog and digital signals. However, it is more involved with digital communication systems.
4. As FDM transmits an analog signal through a single cable, it has little risk of interference within the same channel. But, the same risk of interference is high between users on the same frequency.
5. FDM commonly uses wired communication, while FDMA does its function using wireless communication systems.

Comparison Between FDM and FDMA

Parameter of Comparison	FDM	FDMA
Full form	The complete form of FDM is Frequency Division Multiplexing.	FDMA stands for Frequency Division Multiple Access.
Type of signal	It is mainly used for analog signals.	It can be used for both analog and digital signals.
Medium	Its medium is over wired communication and cables.	Its medium is mainly wireless communication.
Usage	Its application includes broadcasting, analog signal transmission, and cable TV.	Its utilization includes cellular networks, satellite communication and many others.
Purpose	Its main objective is to combine several analog signals for transmission.	Its main objective is to let several devices share a frequency band.

References

1. https://ieeexplore.ieee.org/abstract/document/4699645/
2. https://ieeexplore.ieee.org/abstract/document/1377947/

Last Updated : 14 October, 2023