How does lag work in this game?

I've been having severe lag issues in BF3 recently. I've managed to eliminate my own network as the source of the problem. I've narrowed down the problem to either the BF3 servers or my own wireless adapter on my Xbox.

I invaded a few people last night and there was crazy lag all over the place. I'm talking about terrible lag to the point where the host was teleporting all over the place. When I was invaded, the lag wasn't that bad.

How does the connection work in Dark Souls? When you invade, does the host have the connection? It could be that I invaded people with terrible connections (I only invaded the same 2 people a few times).

I'm still trying to narrow down my problem with lag. If I'm lagging in Dark Souls too, that can mean that the problem has been with my wireless adapter all long.

When people invade me it seems like there isn't a lag at all and I get invaded all the time and I message them to see if everything was good and they say yeah no problems good dual. Now when I invade people, I get some lags and some normal ones. I message them to say u lagged bad man and I'll get either some immature response or ill get someone who actually talks about it. Iv gotten some who say " yeah sorry man my connection is bad", or " it's the servers". I have 100 percent connection when I check on my ps3 status connection so I know it's not a problem on my end. Iv heard that whoever invades, uses the connection of the host. So if your opponent is lagging, so are u. But not a confirmed source so take that for what u will.