In MIMO systems, which mechanism is primarily used to improve reliability besides increasing data rates?

• A. Frequency hopping.
• B. Spatial diversity.
• C. Antenna impedance matching.
• D. Time-division multiplexing.

Answer: (B)

Spatial diversity is the mechanism that boosts reliability in MIMO. By using multiple antennas and creating several independent propagation paths, the same data can be sent over different routes. The receiver combines these paths so that if one path experiences deep fading or interference, the others can still carry the information. This diversity gain reduces the probability of errors and makes the link more robust, even as you pursue higher data rates through other MIMO techniques like spatial multiplexing. The other options don’t primarily enhance reliability in a MIMO context: frequency hopping mainly mitigates interference, impedance matching focuses on efficient power transfer, and time-division multiplexing affects how data is shared over time rather than improving link robustness.