The alternative would be trying to file court cases outside the US for Qualcomm, which is where Huawei does most of its business and infringing.

There's a long history of various companies doing patent license deals like this in the telecom industry. Nokia still earns a lot of money this way, for example. Apple settled with them on a few occasions.

Speaking of which; Apple has its own 5G chips now so they are a bit less dependent on Qualcomm now. Huawei and Apple both have a lot of their own in house technology at this point. But of course Qualcomm always was a strong IP company with lots of patents and its impossible for either to make phones without infringing on at least some of those patterns. And vice versa, a lot of Qualcomm's stuff would necessarily infringe on some patents by others.

That's why these cross licensing deals like this are usually the outcome of disputes around IP.