Spatial multiplexing is one of the important features of LTE technology. By using Spatial multiplexing with MIMO, there is significant improvement in data throughput. In LTE, 2*2 MIMO is supported. Up to 2 TB or codewords can be sent to an UE per TTI.
When an eNodeB receives feedback from UE about rank then based on rank eNodeB starts scheduling more data. There is a lot of dependency on parameter like Pre-coding Matrix Index, Rank Index etc.