UE2 (Green UE) buffer emptied in 5 msec.
So you can see that main difference between user and cell throughput lies in time taken in denominator.
Data in numerator is same.
Separate times for UE is added in denominator instead of flat time duration.
That’s why cell is around 20-22 Mbps and user throughput is around 5-6 Mbps keeping in view data is same for both.
For the sake of convenience you can assume that these boxes things are UE buffers in DL that’s contains data for particular UEs.
Buffer for green UE emptied in 3 intervals of 1Mb+2Mb+3Mb and took total 5msecs
Hope it’s clear now…