What is MIMO and how does it increase link capacity?

• A. Single antenna system with higher power.
• B. Multiple-Input Multiple-Output uses multiple antennas to improve data rates and reliability through spatial multiplexing and diversity.
• C. Uses frequency hopping to improve rate.
• D. Only increases interference.

Answer: (B)

MIMO uses multiple antennas at both the transmitter and receiver to create several independent signal paths between them. This setup lets the system do two powerful things at once.

First, spatial multiplexing: multiple data streams can be transmitted in parallel over the different antenna paths. This means the same bandwidth carries more information, boosting data rates.

Second, diversity: having multiple paths improves reliability. If one path experiences fading or interference, others can carry the data, reducing the chance of a dropped or corrupted link.

Together, these effects increase link capacity and robustness, especially in environments with reflections and scattering that produce distinct propagation paths. Capacity grows with the number of usable antenna paths, provided the environment supports separate channels and the receiver can separate the streams.

The other options don’t capture this combination. A single-antenna system with more power doesn’t generate parallel channels or the same data-rate gains. Frequency hopping is a different technique for resilience or interference avoidance, not the core idea of MIMO. And MIMO isn’t about increasing interference; it’s about adding multiple paths to carry more information more reliably.