Wi-Fi Network Planner

Coverage — log-distance indoor path loss with wall attenuation counted explicitly, solved for the distance at which RSSI reaches your design target. Wi-Fi is planned to a target like −70 dBm rather than to the radio's sensitivity: a client will associate at −85 dBm and be useless. The table is anchored to the office case, where the published rule of thumb is 30–45 m at 2.4 GHz and 15–25 m at 5 GHz from a 20 dBm access point — this model returns 40 m and 17 m.

Capacity is about sessions, not bandwidth — a sensor fleet sends almost no data, but every reading costs a full connect sequence lasting seconds. The number of sensors mid-session at any instant is Little's Law: arrival rate × service time. That is what runs into an access point's concurrent-client limit, and it is why shortening the connect sequence raises capacity as sharply as it extends battery life.

Airtime — only about 8% of a session is actual frames on the channel; the rest is waiting for beacons, the DHCP server and the broker. That fraction is the figure worth measuring on your own site before quoting utilisation to anyone.

Channel reuse — 2.4 GHz has three non-overlapping channels and 5 GHz has nineteen. Co-channel neighbours share airtime rather than adding capacity, so an over-dense 2.4 GHz plan gets slower as you add access points.

A desk estimate on smooth assumptions. Real buildings have lift shafts, foil insulation and metal racking that no model predicts — confirm with a site survey before ordering hardware.