Plan and Design the Wireless Network: RF, Coverage, and Capacity
Start with requirements, not AP count
RF planning begins by translating business requirements into coverage and capacity targets. Coverage is a signal-strength and quality goal: for data, plan around -67 dBm RSSI and at least 20 dB SNR; for voice, -65 dBm and 25 dB SNR. Capacity is a client and throughput goal: estimate active devices per area, average and peak throughput, and client mix (laptops, phones, scanners, IoT). Use 5 GHz as the primary band, reserve 2.4 GHz for legacy and IoT, and set channel width deliberately-40 MHz is a common balance; 80 MHz reduces reuse.
Choose AP models for antenna pattern, band support, PoE class, and mounting. Compute EIRP from radio power + antenna gain - cable loss. Do not design at maximum power; high power increases co-channel interference and sticky clients. Use Aruba ARM or AirMatch to automate channel/power, but validate with a predictive survey and an on-site validation survey. Account for DFS, regulatory domain, and non-Wi-Fi interference.
Worked example
A 600-seat auditorium with two devices per seat has 1,200 devices. At a design target of 40 active clients per AP, capacity requires 30 APs; coverage may need fewer, so capacity governs. Check that 30 APs can be deployed with adequate spacing and 5 GHz channel reuse; if not, reduce cell size or add sectors. Rule of thumb: coverage sets the minimum AP count; capacity sets the real count.