Multiple access in satellite transponders Which access methods allow many Earth stations to share a single satellite transponder simultaneously without mutual interference?

Introduction / Context:
Satellite transponders are expensive shared resources. Multiple access techniques allow multiple users to efficiently share bandwidth and power while keeping interference manageable through separation in frequency, time, or code domain.

Given Data / Assumptions:

• One bent-pipe transponder with fixed bandwidth and gain/back-off limits.
• Users require simultaneous or quasi-simultaneous access.
• Orthogonality or separation is needed to avoid unacceptable interference.

Concept / Approach:

FDMA allocates distinct frequency slots; TDMA assigns non-overlapping time slots; CDMA overlays users with distinct spreading codes that are ideally orthogonal. Each approach permits concurrent usage under proper planning, synchronization, and power control.

Step-by-Step Solution:

Verification / Alternative check:

Commercial and military satellite networks have historically deployed each of these methods, sometimes hybridized (e.g., MF-TDMA).

Why Other Options Are Wrong:

Choosing only one technique ignores the other established methods; “None of the above” is contradicted by decades of practice.

Common Pitfalls:

Assuming a single method is universal; in reality, the selection depends on service type, equipment, and link budgets.

Final Answer:

All of the above