What is RI in LTE?
Thanks dear, I know full form. I mean the use of it in LTE.
Rank indicator is one of the channel state information parameter. Reported by UE and indicates how favorable are channel conditions for MIMO. For example, If UE reports it as 4, it means UE has favorable channel conditions to receive DL data upto 4 layers.
Rank Indicator (RI) which says how many independent layers the channel is capable to handle
One way to look at it is that the Rank indicator from UE to NW is a way of indicating to the network about the number of independent multipaths seen by UE in DL. With this information, the network can map symbols across multiple layers. When there is no multipath environment (as in the case of rural areas with no big buildings etc.), rank is usually set to 1. In a multipath-rich environment (like in the case of urban areas), RI > 1 and network can schedule across multiple layers to improve spectral efficiency.