yep… hsn = 6 or 40, it is pseudo random. so by definition, you can’t know what sequence of frequencies it will produce (random). But you know that HSN = 40 and HSN = 6 will be different. That’s all you need to know, operationally speaking, so there will be know collision.
Now, if you want to program your own BTS and your own frequency hopping module, yeah, you’ll need to know 🙂