LTE & 5G NR link budget — the simple version
Pick a technology, a band, a service and the kind of area you are covering. Change any input on the left, then press Run to update the budgets, the limiting direction, the cell radius and the data rates. Whenever a setting changes, the Run button turns green to show the results on display are stale; after you run, it returns to white.
One model only: the 3GPP model from TR 36.492 / TR 38.901 (the standards model in the workbook), not the proprietary Vendor A or Vendor B models. Path loss uses the 3GPP channel model that matches the morphology you pick.
1 · Technology
LTE (4G) or 5G NR. NR adds wider bands, mmWave, the eMBB service and higher MIMO orders.
2 · Service at the cell edge
The downlink (PDSCH) service the budget must still deliver at the edge of the cell. Faster services need a stronger signal, so the downlink budget gets tighter. The uplink (PUSCH) is budgeted separately, for its own robust 256 kbps-class service, and does not change when you pick a faster downlink — so a demanding downlink really can become the limiting direction.
3 · Band
Lower frequencies travel further but carry less data; higher frequencies are the opposite. The band also decides whether the link is FDD or TDD (see step 5).
Wider channel = faster rates, but a higher noise floor, so a slightly smaller MAPL.
4 · Morphology (area type)
Sets the 3GPP channel model, the base-station height and typical shadow / building-penetration margins. You can still override the margins below.
5 · Duplex mode
How the shared channel time is split between downlink and uplink. It changes the data rates, not the MAPL — the signal still has to travel the same distance.
6 · Antennas & MIMO
More antenna pairs = a real MIMO gain in the budget and more parallel streams (layers) for data.
Higher sites see further, especially in the rural model. The phone is assumed at 1.5 m.
7 · Transmit powers
Phones are battery-limited (23 dBm is the usual class) — this is why the uplink usually limits the cell.
8 · Losses & margins
Spare dB kept aside so coverage still works in dips behind buildings and terrain.
Signal lost going through walls to reach users indoors. Set it low for outdoor-only coverage.
Spare dB for noise from neighbouring cells using the same frequencies.
How much noise the phone's own receiver adds. 7 dB is the workbook value — including for the 700 MHz 256 kbps case (see “Corrections applied”).
Downlink vs uplink budget
| Item | Downlink | Uplink |
|---|---|---|
| Transmit power | – | – |
| Transmitter antenna gain | – | – |
| MIMO gain (real value, not FALSE) | – | – |
| Noise floor in channel | – | – |
| Required signal-to-noise (DL service; PUSCH fixed) | – | – |
| Receiver sensitivity | – | – |
| Margins (shadow + penetration + interference) | – | same |
| MAPL | – | – |
3GPP channel model for this morphology
– 3GPP TR 38.901
How the numbers are worked out
Corrections applied (from the workbook check)
- 4×4 MIMO gain is a real number. The workbook's 36.492 sheet returned the text FALSE for 4×4, which zeroed its data rate. Here every MIMO setting computes a gain — 4×4 gives 6.0 dB — and the rate follows from it.
- 700 MHz 256 kbps case uses a 7 dB phone noise figure. The workbook pointed that one cell at a blank cell, silently using 0 dB and flattering the noise floor by 7 dB. The default above is 7 dB for every band and service.
- The limiting direction is calculated, not typed. The workbook's summary had “UL” typed into every row. Here it is simply whichever of the two MAPLs is smaller, recomputed on every Run.
- PDSCH and PUSCH are budgeted separately. In the workbook there is one uplink (PUSCH) budget and a separate downlink (PDSCH) budget for each downlink rate — e.g. at 700 MHz in dense urban, PUSCH allows 117.0 dB while PDSCH at 1000 kbps allows only 106.9 dB, so that case is downlink-limited. This page now does the same: the service in step 2 sets the PDSCH requirement only, and the PUSCH requirement stays fixed at −5 dB SINR. (An earlier version of this page moved both requirements together, which kept the two MAPLs almost the same distance apart whatever service you picked, so the downlink could practically never become the limiting one.)