It seems you are refering to Inilink which is mostly used in ERICSSON Cell Sites.
This is shorter distance ( Higher Freq MW Links )and has a capcity of MAX-16 PCMs..
Called as PDH.
SDH – Technology can be used in MICROWAVE or OPTICAL.If it is MW used in ( Lower MW Fre Link ) for Longer Distance.Mostly for Ntework Backbone Network like OPTICAL.Normally OPTICAL has more good stability compare to SDH.But SDH is easy to deploy and start operation.
In ERICSSON-AXE810 you can get STM-1 ( 63 PCMs) Output either as Optical/Electrical for MW Links directly from SWICTH MSC/BSC.
This is new…..