Terminology » Satellite Communication » SCPC vs. MCPC in Satellite Communication: Key Differences

SCPC vs. MCPC in Satellite Communication: Key Differences

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Both SCPC and MCPC are terms frequently encountered in satellite communication, especially within the realm of VSAT (Very Small Aperture Terminal) technology. Let’s break down these acronyms and explore their differences.

SCPC stands for Single Channel Per Carrier, while MCPC stands for Multiple Channels Per Carrier.

Let’s delve into each concept before comparing them.

What is SCPC?

  • In SCPC, each communication channel is assigned its own dedicated carrier frequency on the satellite transponder.
  • This means that each communication link has its own dedicated frequency, and operates independently.
  • SCPC is well-suited for point-to-point communication scenarios where a consistent and dedicated bandwidth is required for a specific link.
  • SCPC is generally preferred when the number of channels (voice/data) needed is limited.

SCPC finds its applications in scenarios where a constant data rate is crucial, 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 (combined) and modulated onto a single carrier. At the receiving end, these channels are typically demodulated and demultiplexed to extract the original data streams.
  • MCPC is generally more bandwidth-efficient compared to SCPC because 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 bandwidth needs to be dynamically shared among multiple users.
  • MCPC is commonly used when a larger number of channels is required.

SCPC vs. MCPC

The following table summarizes the key differences between SCPC and MCPC in the context of VSAT and satellite communication:

SpecificationsSCPCMCPC
Full formSingle Channel Per Carrier - a single voice or data channel is modulated and transmitted over one RF carrier.Multiple Channels Per Carrier - Multiple voice and/or data channels are multiplexed (using TDM), modulated, and transmitted over one RF carrier.
Carrier frequency allocationDedicated carrier frequency for each VSAT terminal.Shared carrier frequency among multiple VSAT terminals.
MultiplexingNot providedFDM or TDM
Modulation techniqueFM or PSK (continuous/voice activated). Voice activation is often provided to save power when there is no voice activity.FM or PSK
Carrier Bandwidth (BW) usageFixed 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 P2MWell-suited for point-to-point communication.Suitable for point-to-multipoint communication, allowing multiple terminals to share bandwidth.
ApplicationLow data rate VSATsHigh data rate VSATs
Burst transmissionInefficient for such transmission.Ideal for burst transmission (e.g., packet-based data transmission).
Dedicated connectionUser pays for a dedicated connection, even if the connection is not fully utilized. SCPC DAMA (Demand Assigned Multiple Access) implementation avoids this situation.It does not need a dedicated channel for each connection.
Cost considerationsPotentially more costly, especially for dedicated bandwidth.Can be more cost-effective, especially in scenarios with varying data rate requirements.

Conclusion

In summary, the primary difference between SCPC and MCPC lies in how the carrier frequency is utilized. SCPC dedicates a single carrier frequency to each communication link, ensuring consistent and dedicated bandwidth. MCPC, on the other hand, allows multiple communication channels to share the same carrier frequency, enabling a more efficient use of available bandwidth, which is particularly beneficial for scenarios with varying data rate requirements and multiple users.

The choice between SCPC and MCPC in VSAT satellite technology depends on several factors, including the specific communication requirements, traffic patterns, and budget constraints. SCPC is suitable for dedicated point-to-point links, while MCPC is more efficient for point-to-multipoint communication with dynamic bandwidth needs.