In OFDMA, what is the benefit of dividing the channel into resource units?

• A. Increases single-user throughput only.
• B. Serves multiple users simultaneously, increasing efficiency.
• C. Increases interference.
• D. Reduces security.

Answer: (B)

Dividing the channel into resource units in OFDMA lets the system assign different parts of the spectrum to different users at the same time. Each user gets its own subset of subcarriers, so several users can transmit concurrently rather than taking turns. This parallel use of the spectrum boosts overall efficiency because the same bandwidth serves multiple users, increasing the total data carrying capacity of the link.

The reason this works well is the orthogonality of the subcarriers, which minimizes interference between users’ signals. A scheduler can dynamically allocate resource units based on user needs and channel conditions, making better use of varying wireless environments and QoS requirements.

The other options don’t capture this multi-user benefit: it’s not about increasing throughput for a single user alone, it doesn’t inherently raise interference (it actually helps manage and reduce it through orthogonal coding), and security isn’t the point of resource units.