Indoor and small-cell link budget
First-pass downlink link budget with shadow-fading margin, uplink check, estimated coverage radius and a repeater power-class indication.
Path-loss exponent and penetration are typical engineering values, not standard mandates. Shadow fading uses sigma = 8 dB (urban macro) with z = 1.28 / 1.645 / 2.326. Feeder loss per metre is a typical figure - always confirm against the cable datasheet. Indoor path-loss modelling follows ITU-R P.1238. This is a first-pass calculation for option comparison; final design needs site survey, simulation and on-air measurement.
Next step
Take the coverage radius this calculation produced into the point-and-BOM estimator, and see how many antennas and units the area needs.
Estimate antennas and bill of materials →Common questions
How do I calculate an indoor coverage link budget?
Work from the antenna port outwards: port power plus antenna gain, minus the distribution loss (feeders, splitters, combiners), minus the path loss from the antenna to the edge of the coverage area, minus a shadow fading margin for the confidence level you are designing for. The result has to land on the target level at the edge. This tool does that arithmetic and also checks the uplink, because a link that meets the downlink target can still be uplink limited.
How do I tell if a repeater is uplink limited?
Compare the level that arrives at the base station on the uplink against the receiver sensitivity and the noise floor. If the uplink arrives below what the phone needs to get a decent service level, the downlink can look perfect on the phone - full bars - while calls drop. The uplink check in this tool does exactly that comparison and flags it.
What target level should I design the coverage edge for?
Common indoor design targets are around -75 dBm for LTE and around -80 dBm for NR in distributed systems; the value that matters is the one your customer's acceptance test uses. Whatever you pick, state it in the report - a coverage number without its target level is meaningless.
How much shadow fading margin do I need?
The tool uses a standard deviation of 8 dB, which is typical for urban macro cells, and applies the corresponding normal deviate for the confidence level you choose: 1.28 for 90%, 1.645 for 95% and 2.326 for 99%. That gives margins of 10.2, 13.2 and 18.6 dB respectively. Adjust the standard deviation if you have site-specific measurements.
Can this tool replace a proper propagation study?
No. It is a first-pass calculation for option comparison and for getting a starting point. Final design needs site survey, simulation in Atoll or iBwave, and on-air measurement. Treat a margin that comes out thin as a signal to measure, not as a pass.