Design review
Link budget, n78 small cell
Will a 3.5 GHz street-level cell cover a 200 m block? A five-minute walk through the maths.
RF Systems teamSample deck, illustrative numbersOctober 2026
Every doubling of distance costs 6 dB.
Free space, any frequency. Walls, foliage and bodies come on top.
Link budget
Add the gains, subtract the loss
Pr = Pt + Gt + Gr − Lfs
- Pt
- Transmit power, 43 dBm
- Gt
- Antenna gain, 17 dBi
- Gr
- Handset gain, 0 dBi
- Lfs
- Free-space loss, 89.3 dB at 200 m
Loss grows 6 dB per doubling
From 77 dB at 50 m to 101 dB at 800 m.
| Distance | Free-space loss |
|---|---|
| 50 m | 77.3 |
| 100 m | 83.3 |
| 200 m | 89.3 |
| 400 m | 95.4 |
| 800 m | 101.4 |
Signal chain
From radio to handset, in dB
What the margin has to cover
−29dBmReceived power, free space
−12dBWall and body loss allowance
17dBMargin left before the receiver floor
Review outcome
Coverage holds
Next drive-test the 400 m edgerf-team@example.com