[randywaterhouse]

Sniper in Mahwah [1] details a lot of the structure of HFT trading infrastructure, especially how microwave towers are used. It's a rabbit hole though, he's got tons of stuff on the various ways HFT networks make things work, including their licensing and contracting.

[1] https://sniperinmahwah.wordpress.com

[tomalpha]

I remember talking to a guy who worked on an HFT firm's in-house microwave network. Sniper In Mahwah is (or at least was - I'm a little out of that world these days) pretty much bang on the mark. It's amazing what you can find out from public records, a bit of cycling and a lot of collating.

Edit: reading through some of his more recent updates I think he's still on the money