R11e-LTE is a Cat.4 LTE modem. This means it utilizes 2x2 MIMO in downlink.
Diversity here is a bit misleading, since the diversity is working only in uplink direction. Second antenna port can work for second spatial stream. If both eNB and modem support TM3 (which it should) or even TM4, you get a working 2x2 MIMO in DL.
For fastest possible speed in DL, and less errors in UL, connect all antenna ports.