RoHC for VoLTE and Cell Coverage

Hello mates,

When i have a look of Robust Header Compression feature. The main purpose of RoHC is to compress the headers of primarily radio bearers carrying VoIP calls in order to increase capacity and it seems coverage ?

When i read about this feature it is said one of the benefit is " increases the cell coverage when segmentation occurs during H-ARQ retransmissions.

Here is my question :

I understand RoHC increase the capacity but why the cell coverage exactly ?
Why by reducing the size of a VoIP packet this will increase cell coverage ?

Thanks in advance for your feedback.