We could set aside land from immigrants to come to, separate to native society. If they, over a set period of time, prove themselves to be law abiding and there is space in the country, they can integrate. If they are not law abiding, they can stay there or go somewhere else.
I hate this idea for so many reasons.
Firstly, and most obvious one, you'd need the government to buy or seize land from its citizens, and then give it to foreigners. I can only imagine how thrilled people will be when they learn that.
Secondly, you're just gonna create a proxy country inside your own country, segregation never really worked well, and chances are you're just gonna end up with a bunch of people wanting their own laws and rules, making any prospect of them joining the "main" country an impossible thing.
Thirdly, you're not helping anyone assimilate into your country, which MUST be your objective with immigration. You got to offer people education, teach them your culture and language, offer them the same rights as citizens and the same duties as well.
Fourthly, the best way to assimilate large ammounts of migrants is to spread them out in your country, putting everyone into "guettos" will make it impossible for them to really become citizens.
Lastly, it's very hard to measure if someone is ready to integrate your society, you have very subjective jugements to make, you need to put a lot of ressources into it, and at the end of the day you can just fail, letting people that shouldn't enter, in, and people that should enter, out (a lot like prison lol).