Its not required, but useful. If you have a 4T4R antenna and 4x4MIMO is not possible (due to radio conditions) - which is a likely scenario - the only way to benefit from your 4T4R system is Tx (and Rx) diversity. If you configure your cell to 4T4R, it will be Tx div on all non-MIMO channels. Of coarse you can configure your 4T4R antenna to 2T2R, but unless you save in terms of license, thats a waste of resources (you already payed for the 4T4R antenna, RRU and chains). In my view, you can benefit the most from a 4T4R system mainly with 4 way receive diversity (effectively doubles the uplink gain compared to 2 way, those improves the uplink imbalance), and beamforming. Switching on 4x4 MIMO is only realistic, if you have a large number of 4x4 MIMO capable UEs, and a reflective enough environment. In any other case turning on 4x4 MIMO will just increase the CRS overhead without much gains.
Bookmarks