I’ve been working for almost 3 years on LWA ( we actually proposed something earlier than LWA, that we called Very Tight Coupling between LTE and WiFi). We even developed it and implemented it on a real-time testbed. So I think I can provide some answers.
- Major points to consider: It is not clear whether 3GPP intends to use WiFi and LTE simultaneously, or just one at a time, in our case we tried both. So if you use them both simultaneously, I think the most important conclusions we end up with is that if the difference between the delays on WiFi and LTE is too large, the throughput will be worse when using both then when using a single interface. So you need very powerfull traffic steering mechanisms to be sure that will not in this case, and to always make sure to use a “good” WiFi AP.
The 3GPP did not consider at all how to connect WiFi AP to LTE eNodeB. We studied that a lot and it is not so easy as it looks like. For our case, our work is a part of a European project and we consider a converged fixed-mobile network where both accesses share the same layer 2 network. So the connection is easier than when having both networks completely independant.
For VoWIFI, we did not think about it, but I think what I said just now might help. Do not forget that LWA intends to reuse existing WiFi APs and not having new ones only to this purpose. So you may be using loaded APs with a lot of users already associated, and thus more or less bit rate and higher collisions and interference.
For further information on what I just said, we already published couple of papers. Just type Very Tight Coupling between LTE and WiFi. We have some interesting results also.
If you have any other questions, do not hesitate to answer, or contact me directly.