Academia
http://ece.nitc.ac.in/index.php?option=com_php&Itemid=66&uname=sameer
http://ece.nitc.ac.in/index.php?option=com_php&Itemid=66&uname=lilly
https://www.ece.ucf.edu/~yuksem/ south florida
https://vbn.aau.dk/en/persons/104398
https://vbn.aau.dk/en/persons/126055
https://vbn.aau.dk/en/persons/138370 : AAU
http://www2.aueb.gr/users/vsiris/
http://www.techplayon.com/5g-nr-gnb-logical-architecture-functional-split-options/
https://www.o-ran.org/ : O-RAN
https://www.parallelwireless.com/products/wifi-openran-controller/
Protocol Stack:
Radio Protocol Architecture of LTE/5G is divided on two planes: Control Plane (C-plane) and User Plane (U-plane).
At user plane side, the application creates data packets that are processed by protocols such as TCP, UDP and IP, while in the control plane, the radio resource control (RRC) protocol writes the signalling messages that are exchanged between the base station and the mobile.
In both cases, the information is processed by the packet data convergence protocol (PDCP), the radio link control (RLC) protocol and the medium access control (MAC) protocol, before being passed to the physical layer for transmission.
https://www.artizanetworks.com/resources/tutorials/pro_sta.html
https://www.netmanias.com/en/post/oneshot/14103/5g/5g-protocol-stack-user-plane-control-plane
Functional Split:
A functional split determines the amount of functions left locally at the antenna site, and the amount of functions centralized at a high processing powered datacenter. In NR the radio processing-- and baseband-- functions from the 3rd Generation Partnership Project (3GPP) protocol stack are split up into a Distributed Unit (DU) and a Centralized Unit (CU). The red lines within figure 2 illustrate different options for functional splits, and the functions below the red line will be the functions implemented in the DU, where the functions above the red line will be performed in the CU.