DAS acceptance means verifying that the system does what it was designed to do: serve the building interior with a dominant cell, without spilling over into the street and without degrading the uplink. The criteria are set before the walk and verified against the measurements, zone by zone.
1. Setting the criteria before measuring
- Level: minimum RSRP or SS-RSRP per zone, for example −95 dBm on 95% of the points in office areas; the target depends on the band and on the intended service.
- Quality: minimum SINR, typically 10 dB on 90% of the points for a sustained data service.
- Dominance: margin over the best outdoor cell, with a 6 dB target — the most demanding criterion along façades and on high floors.
- Leakage: indoor cell level a few meters from the façades, so that it does not capture traffic from the street.
- Uplink: device transmit power consistent with the measured path loss, and a healthy uplink noise floor both unloaded and under load.
- Services: downlink and uplink throughput, latency and voice calls at representative points.
2. Building a repeatable route
The route covers the façades, where dominance is decided; the circulation areas, waiting areas, stairwells and elevators; the basements and the entrances, where the transition to the macro network takes place. Written down and drawn on the floor plan, it allows exactly the same walk to be repeated after correction: this is the prerequisite for a credible before/after comparison.
3. Positioning without GPS
Floor plans are calibrated on two reference points that are easy to identify on site — corners, pillars, doors. Waypoints are placed closer together at changes of direction and the walking pace is kept steady: the position of each sample is interpolated between two timestamped points.
4. Reading the results
- The floor plan colored by SINR rather than by RSRP alone: a high level says nothing about dominance.
- The margin between the serving cell and the best neighbor, zone by zone.
- The inventory of cells detected on each floor, to identify the macro cells entering through the façades.
- Events: pilot pollution, dominant neighbor, high BLER.
- Device transmit power, the first indicator of an uplink problem.
5. Common pitfalls
- Measuring only in corridors, where the DAS always performs well.
- Judging coverage by RSRP without looking at SINR.
- Overlooking the uplink: a shared DAS can generate passive intermodulation that raises the uplink noise floor as soon as the carriers are loaded.
- Comparing different walks before and after correction.