Explore how frequency, distance, antenna configuration, bandwidth, and building-entry assumptions affect an illustrative radio link.
Model baseline: 3GPP TR 38.901 V18.0.0 (May 2024) · Interactive engineering explorer
fr3simulation.com
Educational demonstration — not engineering advice. Illustrative median, SNR-only results use published statistical relationships and stated assumptions. They are not measurements, coverage predictions, compliance assessments, or performance guarantees. Do not use them to design, purchase, configure, certify, deploy, or operate networks; obtain qualified review and independent validation.
Before Using the FR3 Link Budget Explorer
This explorer provides illustrative calculations using selected published statistical relationships and simplified engineering assumptions. Results are not measurements, certified engineering outputs, validated coverage predictions, or performance guarantees.
Review the educational limitations, then confirm to enable the interactive controls.
This explorer is a reference demonstration. LJP holds related technical identities for upper-mid-band radio engineering; the identities name roles and are not operating tools. Explore the Semantic Identity Library.
Illustrative · median · SNR-only. Interference, loading, and deployment constraints are outside this model.
Median distance where SNR falls to −5 dB
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Illustrative threshold distance; not a coverage guarantee.
Illustrative single-layer rate at probe
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Theoretical/simplified estimate; not actual NR throughput.
Extra path loss vs 3.5 GHz
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Idealized array-gain difference
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Idealized assumption; realized antenna performance will differ.
SNR versus distance
SNR-threshold radius = farthest distance with SNR ≥ −5 dB (dotted line), an assumption of this explorer, not a 3GPP coverage definition. Median statistical path loss; LOS probability, interference and scheduling are not modeled. Rates are Shannon-based illustrations, not an NR throughput model.
Link budget at 300 m
Evidence ledger
From published specifications Level A
Median path loss for UMa and UMi street canyon, LOS and NLOS, including the breakpoint distance: 3GPP TR 38.901, clause 7.4.1, Table 7.4.1-1 (formulas applicable 0.5–100 GHz, 10 m to 5 km).
Material losses (standard glass, IRR glass, concrete), low-loss and high-loss building entry models, and indoor loss of 0.5 dB/m: TR 38.901, clause 7.4.3, Tables 7.4.3-1 and 7.4.3-2.
Shadow-fading standard deviations quoted in the margin hint: TR 38.901, Table 7.4.1-1.
Version checked: TR 38.901 V18.0.0 (published by ETSI as TR 138 901 V18.0.0, May 2024). Later Release 19 versions add scenarios and effects (for example suburban macro, near-field and spatial non-stationarity); this explorer has not yet been re-checked against them.
Studies in progress Level B
WRC-27 agenda item 1.7 studies 4.4–4.8 GHz, 7.125–8.4 GHz and 14.8–15.35 GHz for possible IMT identification. These bands are under study, not identified.
For terrestrial NR, "FR3" is widely used informally for upper-mid-band spectrum between today's FR1 (up to 7.125 GHz) and FR2 (from 24.25 GHz) ranges. It is not currently a formal 3GPP frequency-range designation. 3GPP's Release 19 channel-modeling study addressed the 7–24 GHz range.
Established engineering constants
Thermal noise density of −174 dBm/Hz: kT at a reference temperature of 290 K (about −173.98 dBm/Hz), the conventional room-temperature approximation used in link budgets.
Rate estimate uses the Shannon bound, log₂(1 + SNR), as an upper-bound illustration.
Assumptions made here Level E
Array: 5 dBi per element, idealized gain = element gain + 10·log₁₀(elements); 64 elements at 3.5 GHz; same-panel scaling capped at 1,024. RF losses, element coupling, scan loss, beamforming efficiency, power-amplifier limits and regulatory EIRP limits are not modeled.
Terminal: 0 dBi antenna; noise figure 7 dB (FR1), 9 dB (FR3), 10 dB (FR2); 3 dB body and implementation loss.
Indoor users use an assumed 8 m indoor distance (a typical mean-scale choice, not a site measurement). The model adds it to the outdoor 3D path length and applies 0.5 dB/m indoor loss; base-station height is 25 m (UMa) or 10 m (UMi); terminal height is 1.5 m.
Downlink only; single user; no interference (SNR, not SINR).
Illustrative rate: one layer, full-cell power toward one user, 25% overhead, spectral efficiency capped at 7.4 bit/s/Hz, zero below −10 dB. No MCS tables, BLER target, HARQ, TDD split, scheduler or multi-layer MIMO.
SNR-threshold radius at −5 dB SNR: a comparison convention, not a coverage definition.
References: 3.5 GHz with 100 MHz; 28 GHz with 400 MHz.
Measurement boundary
This explorer is not calibrated against field measurements. Published measurement studies can inform separate qualified engineering review, but are not used here as a performance-validation or calibration claim.
FR3 link-budget questions
Why does FR3 lose more signal than 3.5 GHz?
In TR 38.901's urban-macro formulas, median path loss rises by 20·log₁₀ of the frequency ratio: about 7 dB more at 7.8 GHz than at 3.5 GHz, and about 12.6 dB more at 15 GHz, at the same distance. The physical reason is that a single antenna element of fixed gain captures less energy as the wavelength shortens. Building entry loss also rises with frequency, most sharply through concrete.
Can massive MIMO recover the FR3 link-budget gap?
Partly, in principle. If a base-station panel keeps the same physical size, the number of elements it can hold grows with the square of frequency. That adds up to 20·log₁₀ of the frequency ratio in idealized array gain, which on the downlink roughly offsets the free-space part of the extra loss. It does not offset the extra building loss. Real arrays give back some of that gain to RF losses, coupling, scan loss and beamforming efficiency, and regulatory EIRP limits may apply. The uplink is usually harder, because the terminal's power and antenna do not scale the same way. Use "Same panel size" and "Same 64 elements" above to see both cases.
Why is indoor FR3 coverage difficult?
TR 38.901 models concrete loss as 5 + 4·f dB (f in GHz): about 19 dB at 3.5 GHz but about 36 dB at 7.8 GHz. Indoor signal therefore arrives mostly through windows. Energy-efficient (IRR) glass adds 23 + 0.3·f dB of its own, so buildings with modern glazing are the hardest case. Switch "User location" to compare.
What is the difference between this explorer and FR3 ray tracing?
This explorer uses statistical median path loss: the average behavior across many sites of a scenario type. Ray tracing computes propagation for one specific geometry, including the actual buildings, streets and materials. The statistical model is useful for comparing bands and assumptions; ray tracing and measurement are needed for a particular deployment.
Why are 7.125–8.4 GHz and 14.8–15.35 GHz important?
With 4.4–4.8 GHz, they are the bands that WRC-27 agenda item 1.7 will study for possible identification for IMT (mobile broadband). Identification is decided at the conference and has not been made. Actual availability in any country also depends on national regulators and on sharing with existing users of the bands.
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