Okumura-Hata Path Loss Prediction Model
Also known as: path loss model, propagation prediction
The Okumura-Hata model is an empirical propagation model for predicting path loss in mobile radio systems. Developed by Okumura (1968) and mathematically formalized by Hata (1980), it is one of the most widely used models for cellular network planning. The model predicts median path loss as a function of frequency, distance, and antenna heights, with environment-specific correction factors. Despite its age, the Okumura-Hata model remains a standard in 2G/3G planning and is often used as a baseline for more sophisticated models.
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When to use it
Use the Okumura-Hata model for initial network planning, feasibility studies, and coverage predictions in the 150 MHz - 1.5 GHz band (GSM, CDMA, early LTE). The model is most accurate at distances 1-100 km in suburban/open areas; accuracy degrades in dense urban areas with significant multipath. Avoid for frequencies > 2 GHz (use Extended Hata or other models). For detailed site-specific predictions, use ray-tracing propagation models; Okumura-Hata is too coarse.
Strengths & limitations
- Simple closed-form formula; no complex computation required for quick estimates
- Well-calibrated for 2G/3G systems; empirically grounded in extensive measurements
- Environment-dependent correction factors capture main terrain effects
- Accounts for antenna height effects, important for tall base station antennas
- Widely recognized standard; facilitates communication between vendors and planners
- Empirical model; accuracy is limited to measurement conditions (Tokyo, 1960s)
- Log-normal fading variability is typical but not universal; some environments have different statistics
- Frequency range limited to 150 MHz - 1.5 GHz; does not extend to high frequencies (2 GHz+)
- Distance range 1-100 km; model is inaccurate at very short distances (<100 m) or very long distances
- Urban/suburban/open categories are coarse; detailed clutter information is ignored
Frequently asked
Why does path loss increase logarithmically with distance?
Electromagnetic wave power spreads over an area proportional to distance squared (4π d^2). Path loss is the ratio of transmitted to received power, so it scales as d^2. In decibels, this becomes 20 log10(d), hence the logarithmic dependence. The Okumura-Hata formula captures this with a 40 dB/decade slope.
What does the height correction factor do?
Taller transmit antennas have better line-of-sight and reduced blockage, lowering path loss. The formula log10(h_tx) term captures this: doubling antenna height reduces path loss by ~6 dB. Similarly, receive antenna height affects path loss but with smaller coefficient (less critical).
Why is the model inaccurate in dense urban areas?
Dense urban environments have high buildings, narrow streets, and complex scattering that the simple urban category does not capture. Okumura measured in Tokyo of the 1960s, less dense than modern cities. Modern models add detailed clutter information (building height, street width) for accuracy.
How is the model extended to higher frequencies (2 GHz+)?
Empirically, path loss increases faster at higher frequencies due to atmospheric absorption and increased scattering. COST 231-Hata and 3GPP models extend the formula with frequency-dependent terms. For accurate predictions above 2 GHz, measurement-based models or ray-tracing are preferred.
Sources
- Okumura, Y., Ohmori, E., Kawano, T., & Fukuda, K. (1968). Field strength and its variability in VHF and UHF land mobile radio service. Review of the Electrical Communication Laboratory, 16(9-10), 825-873. link ↗
- Hata, M. (1980). Empirical formula for propagation loss in land mobile radio services. IEEE Transactions on Vehicular Technology, VT-29(3), 317-325. DOI: 10.1109/T-VT.1980.23859 ↗
How to cite this page
ScholarGate. (2026, June 3). Okumura-Hata Path Loss Prediction Model. ScholarGate. https://scholargate.app/en/telecommunications/okumura-hata-model
Which method?
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