Difference between SCPC and MCPC in satellite communication

Both of SCPC and MCPC terms are associated with satellite communication, particularly in VSAT technology. The full form of SCPC is Single Channel Per Carrier and MCPC is Multiple Channels Per Carrier. Let us understand each before we explore differences between them.

What is SCPC ?

➨In SCPC, each communication channel is assigned its own carrier frequency on the satellite transponder.
➨A dedicated carrier frequency is allocated for each communication link, and each channel operates independently of others.
➨SCPC is suitable for point-to-point communication where a constant, dedicated bandwidth is required for a specific link.
➨SCPC is used where-in requirement of number of channels(voice/data) is limited or less. It is often used in applications where a constant data rate is needed, such as video conferencing or dedicated data links.

What is MCPC ?

➨In MCPC, multiple communication channels share the same carrier frequency on the satellite transponder.
➨Different channels are multiplexed and modulated onto a single carrier, and these channels are typically demodulated and demultiplexed at the receiving end to extract the original data streams.
➨MCPC is more bandwidth-efficient compared to SCPC, as it allows for the simultaneous transmission of multiple data streams over the same frequency band.
➨This makes MCPC suitable for point-to-multipoint communication scenarios where multiple VSAT terminals communicate with a central hub or where there is a need to share bandwidth dynamically among multiple users.
➨MCPC is used where-in number of channels required is more.


Following table compares SCPC versus MCPC with respect to its usage in VSAT and satellite communication technologies and provides difference between SCPC and MCPC.

Specifications SCPC MCPC
Full form Single Channel Per Carrier-single voice or data channel is modulated and transmitted over one RF carrier Multiple Channels Per Carrier-Mlutiple voice and/or data channels are multiplexed(using TDM),modulated and transmitted over one RF carrier
Carrier frequency allocation Dedicated carrier frequency for each VSAT terminal. Shared carrier frequency among multiple VSAT terminals.
Multiplexing Not provided FDM or TDM
Modulation technique FM or PSK(continuous/voice activated), voice activation is provided to save power when there is no voice activity FM or PSK
Carrier Bandwidth (BW) usage and BW efficiency Fixed bandwidth allocation for each VSAT terminal. May result in under-utilization of bandwidth when traffic varies. Dynamic bandwidth allocation, providing flexibility to adapt to changing traffic patterns. Hence it is more bandwidth efficient due to dynamic sharing of bandwidth among multiple users.
P2P and P2M Well suited for point to point communication. Suitable for point to multipoint communication, allowing multiple terminals to share bandwidth.
Application low data rate VSATs High data rate VSATs
Burst transmission Inefficient for such transmission. Ideal for burst transmission e.g. packet based data transmission.
Dedicated connection User pays for dedicated connection even if connection is not used. SCPC DAMA implementation avoids this situation. It does not need dedicated channel for each of the connection.
Cost considerations Potentially more costly, especially for dedicated bandwidth. Can be more cost effective, especially in scenarios with varying data rate requirements.

Conclusion: In summary, the main difference lies in how the carrier frequency is utilized. SCPC dedicates one carrier frequency per communication link, ensuring constant and dedicated bandwidth for each link. On the other hand, MCPC allows multiple communication channels to share the same carrier frequency, providing more efficient use of available bandwidth, making it suitable for scenarios with varying data rate requirements and multiple users. The choice between SCPC and MCPC in VSAT-satellite technology depends on factors such as the specific communication requirements, traffic patterns, and cost considerations. SCPC is suitable for dedicated point-to-point links, while MCPC is more efficient for point-to-multipoint communication with dynamic bandwidth needs.


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