It all depends on the maps you have. If it's only digital terrain model and clutter classes, then Okamura–Hata. If this is a city and you have vectors of buildings and vegetation, then this is a ray-tracing model
I assume that you are looking something related to 802.15 or home systems. Here are some results in the paper regarding model and measurements...
I hope it helps. If we consider ITU models, 1546 covers the frequency band but it is slightly pesimistic.
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