Can someone explain what is VRB in LTE, how it is different than PRB and where shall we use terms VRB and PRB ?

Question

Since eNodeB can have information about channel quality with finer granularity through selected
subband CQI, wouldn’t it make sense to have MCSs defined on a per‐RB (or a group of RB) basis rather
than a single MCS per UE across all allocated RBs for a codeword?

Answer 1

Hi,

As i know VRB and PRB is just a term to differentiate the RB in MAC and PHY. Like in Linux we have virtual address and physical address , only thing in Linux virtual address can map to any of physical address in RAM ,the same way here one VRB can map to any one of available PRB. If LTE has 25 Rb's then there will be 25 VRB and 25 PRB. If mac scheduler 5 RB to one UE then those 5 VRb can be mapped direct to PRB or based on RAT(resource allocate type) frequency domain scheduler will map. say e.g if RAT is 2 then direct mapping between VRB and PRB ,will happen like 1 - 1,2-2 .3-3.4-4,5-5. If RAT is bit mapped then it can be 1-1,2-4,3-5,4-6,5-8.

Answer 2

http://tech.queryhome.com/124115/prbs-prbs-20mhz-physical-layer-level-mapped-rbs-20mhz-level

Hope it helps !!