An engineer is designing a high-density WLAN that must support 100 concurrent users with 100...

This question requires straightforward wireless capacity engineering calculation. The total throughput requirement is 100 users × 1 Mbps per user = 100 Mbps aggregate. Each channel in the design can support 20 Mbps of usable throughput — this is the per-cell, per-channel allocation defined in the design parameters, representing usable throughput prior to RF overhead as stated in the question. The number of channels required is therefore: total required throughput divided by throughput per channel = 100 Mbps ÷ 20 Mbps per channel = 5 channels. In practice, each channel corresponds to a non-overlapping frequency assignment in the 5 GHz band. With 5 channels and 20 Mbps per channel, the design provides exactly 100 Mbps of aggregate capacity for 100 concurrent users at 1 Mbps each. This calculation methodology is foundational to Cisco ' s high-density WLAN design approach, where the number of spatial streams, channel allocations, and AP placement are all derived from the per-user throughput requirement multiplied by the concurrent user population. Reference: WLSD Study Guide — High-Density WLAN Capacity Planning, Per-User Throughput Calculation, Channel Planning and Spatial Reuse.