Enter transmit power and antenna gains
Use values appropriate to the radio and antennas in the direction being modeled.Set receiver sensitivity
Enter the minimum receive power required for the chosen service threshold, modulation target, or vendor design assumption.Reserve a fade margin
Subtract a design margin for shadowing, fading, and uncertainty rather than planning exactly at receiver sensitivity.Define the propagation model
Enter the reference path loss at 1 meter and the path-loss exponent representing the environment.Review the estimated radius
Use the radius for comparison and screening, then validate candidate designs with a frequency- and environment-specific RF model.
5G Small Cell Coverage Radius Calculator
The 5G Small Cell Coverage Radius Calculator estimates a radio range from a simplified logarithmic-distance path-loss model. It builds a maximum allowable path loss from transmitter power, antenna gains, receiver sensitivity, and fade margin, then compares that budget with a reference path loss and propagation exponent to estimate the radius at which the link budget is exhausted.
The result is useful for early feasibility checks, scenario comparisons, and understanding how link-budget assumptions affect nominal small-cell reach. It is not a site-specific RF prediction. Buildings, clutter, frequency, antenna height, beamforming, interference, uplink limits, local regulations, and vendor radio behavior can change real coverage substantially. For deployment decisions, validate the assumptions with a propagation model appropriate to the environment and with field measurements.
5G small cell link-budget inputs
dBm
dBi
dBi
dBm
dB
dB
n
Result
—
estimated coverage radius
Maximum allowable path loss—
Radius in kilometers—
Estimated diameter—
Maximum path loss = Tx power + Tx antenna gain + Rx antenna gain − Rx sensitivity − Fade marginRadius (m) = 10^((Maximum path loss − Reference loss at 1 m) ÷ (10 × Path-loss exponent))
Where:
- Tx power — transmit power in dBm
- Tx/Rx antenna gain — antenna gains in dBi
- Rx sensitivity — minimum acceptable received power in dBm
- Fade margin — reserved link-budget margin in dB
- Reference loss at 1 m — path loss in dB at one meter
- Path-loss exponent — dimensionless rate at which path loss increases with distance in the selected model
Assumptions: The calculator uses a single-slope log-distance path-loss model. It does not separately model walls, diffraction, terrain, interference, frequency-selective fading, or uplink/downlink asymmetry.
What the result means
The main result is the distance at which the simplified path-loss model reaches the maximum allowable path loss from the entered link budget.
Coverage radius is a planning estimate, not a guarantee of service quality. The limiting uplink or downlink direction should be modeled separately when their budgets differ.
Given:
- Tx power: 30 dBm
- Tx antenna gain: 5 dBi
- Rx antenna gain: 0 dBi
- Receiver sensitivity: −100 dBm
- Fade margin: 15 dB
- Reference loss at 1 m: 40 dB
- Path-loss exponent: 3.0
Calculation:
Maximum path loss = 30 + 5 + 0 − (−100) − 15 = 120 dB
Radius = 10^((120 − 40) ÷ (10 × 3.0))
Radius = 10^2.6667 ≈ 464.2 m
Result: about 464.2 m radius
Interpretation: Under this simplified propagation model, the link budget reaches its threshold at roughly 0.464 km from the small cell.
What does the path-loss exponent represent?
It controls how quickly modeled signal loss increases with distance. Lower values represent more favorable propagation; higher values represent environments where obstacles and clutter cause signal strength to decay faster.
Why include a fade margin?
A margin prevents the design from relying on the exact receiver-sensitivity threshold. It reserves link budget for shadowing, fading, model error, and other variability.
Does this calculator account for operating frequency?
Not directly. Frequency influences the reference path loss and the appropriate propagation model, so use a reference-loss value and exponent suitable for the band and environment being studied.
Can I use the radius as a guaranteed cell boundary?
No. Real coverage is irregular and can be limited by buildings, terrain, interference, uplink power, antenna patterns, and service-quality requirements.
Why might uplink coverage be smaller than downlink coverage?
The user equipment and the small cell can have different transmit powers, antenna gains, receiver performance, and interference conditions. Model the limiting direction separately when those budgets differ.