5G NR Link Budget Calculator — 3GPP TR 38.901 Path Loss, SINR & Range

A link budget adds up everything between a transmitter and a receiver and asks whether the signal arrives with enough margin. Two parts of a 5G NR budget come from the standard itself: the path-loss model, taken here from the 3GPP channel model TR 38.901, and the noise bandwidth, set by the number of resource blocks in the carrier.

Path loss from TR 38.901

TR 38.901 Table 7.4.1-1 gives the median path loss for four deployments: rural macro (RMa), urban macro (UMa), urban micro street canyon (UMi) and indoor office (InH). Each has a line-of-sight (LOS) formula and a non-line-of-sight (NLOS) one. Outdoors the LOS loss steepens beyond a breakpoint distance, where the ground reflection starts to cancel the direct ray. For UMa

with both antenna heights reduced by an effective environment height of 1 m. Below the breakpoint $PL_1 = 28.0 + 22\log_{10}(d_{3D}) + 20\log_{10}(f_c)$, with $f_c$ in GHz and the direct distance $d_{3D}$ in metres. The NLOS loss is the larger of the LOS loss and the NLOS formula, which for UMa is $13.54 + 39.08\log_{10}(d_{3D}) + 20\log_{10}(f_c) - 0.6(h_{UT} - 1.5)$. At 3.5 GHz and 500 m from a 25 m mast the two give 98.27 dB and 129.92 dB: the line-of-sight state decides most of the budget.

Noise and SINR

The receiver noise is the thermal noise in the occupied bandwidth plus the noise figure:

where $kT_0$ is −173.975 dBm/Hz at 290 K. A 100 MHz carrier at 30 kHz subcarrier spacing has 273 resource blocks occupying 98.28 MHz, so its thermal noise is −94.05 dBm before the noise figure. The interference margin raises that floor to allow for other cells, and the SINR is the received power over the raised floor.

Margin and range

The maximum allowable path loss is what the transmit power and antenna gains can lose before the SINR falls to the required value, after the shadow-fading margin has been set aside. The link margin is that limit less the path loss, and the maximum range is the distance at which the path loss reaches it. The shadow-fading standard deviation of the scenario is shown to help choose the margin: about 1.28 standard deviations covers 90% of locations at a given distance.

Peak data rate

The peak rate is the approximation of TS 38.306, section 4.1.2:

with $v$ MIMO layers, $Q_m$ bits per modulation symbol, a scaling factor $f$, and an overhead $OH$ of 0.14 for FR1 downlink, 0.08 for FR1 uplink, 0.18 and 0.10 in FR2. Four layers of 256-QAM on 273 resource blocks at 30 kHz give about 2337 Mbps.

Validity

Each scenario holds over the ranges of Table 7.4.1-1: 0.5 to 100 GHz (30 GHz for RMa); 10 m to 5 km of ground distance (10 km for RMa in line of sight); user heights of 1.5 to 22.5 m in UMa and UMi and 1 to 10 m in RMa; base-station heights of 10 to 150 m in RMa, and exactly 25 m in UMa and 10 m in UMi; and 1 to 150 m of direct distance indoors. Outside them the path loss is still shown, with a warning naming the bound. The maximum range is searched only inside the scenario's distance range: when the link would still close at the far limit, the range is given at that limit with a warning. The breakpoint uses the exact speed of light, where TR 38.901 writes 3.0×10⁸ m/s. Resource blocks are defined only in FR1, up to 7.125 GHz, and in FR2, from 24.25 GHz; between them no noise, margin or rate is given. The probability of line of sight is not applied, and UMa keeps an effective environment height of 1 m even above 13 m, where TR 38.901 draws it at random.