A method of operation in a gateway node that is coupled to a core network of a wireless communication network , the method comprising: determining that data is available for sending to a wireless device that accesses the wireless communication network via a radio cell provided by a radio node that is coupled to the core network of the wireless communication network via the gateway node ; generating service data units corresponding to the data, based on processing the data according to an upper portion of a radio protocol stack , wherein the radio protocol stack is split between the gateway node , which implements the upper portion of the radio protocol stack, and the radio node , which implements a remaining, lower portion of the radio protocol stack ; establishing an Internet Protocol, IP, session towards the radio node , via an intra-stack IP link communicatively coupling the upper portion of the radio protocol stack at the gateway node with the lower portion of the radio protocol stack at the radio node , said IP session mapped to a radio bearer to be used for conveying the data to the wireless device via an air interface of the radio cell ; encapsulating the service data units in one or more IP packets, according to IP session parameters associated with the IP session ; and sending the IP packets to the radio node via the IP session , for de-encapsulation and recovery of the service data units, for subsequent processing by the radio node according to the remaining, lower portion of the radio protocol stack , wherein the radio protocol stack includes as said upper portion a Packet Data Convergence Protocol, PDCP, layer, and a Radio Resource Control, RRC, layer and includes as said lower portion a Radio Link Control, RLC, protocol layer below the PDCP layer, a Medium Access Control, MAC, protocol layer below the RLC protocol layer, and a Physical, PHY, protocol layer below the MAC protocol layer, characterized in that the intra-stack IP link communicatively couples the gateway node to the RLC protocol layer at the radio node . determining that data is available for sending to a wireless device that accesses the wireless communication network via a radio cell provided by a radio node that is coupled to the core network of the wireless communication network via the gateway node ; generating service data units corresponding to the data, based on processing the data according to an upper portion of a radio protocol stack , wherein the radio protocol stack is split between the gateway node , which implements the upper portion of the radio protocol stack, and the radio node , which implements a remaining, lower portion of the radio protocol stack ; establishing an Internet Protocol, IP, session towards the radio node , via an intra-stack IP link communicatively coupling the upper portion of the radio protocol stack at the gateway node with the lower portion of the radio protocol stack at the radio node , said IP session mapped to a radio bearer to be used for conveying the data to the wireless device via an air interface of the radio cell ; encapsulating the service data units in one or more IP packets, according to IP session parameters associated with the IP session ; and sending the IP packets to the radio node via the IP session , for de-encapsulation and recovery of the service data units, for subsequent processing by the radio node according to the remaining, lower portion of the radio protocol stack , wherein the radio protocol stack includes as said upper portion a Packet Data Convergence Protocol, PDCP, layer, and a Radio Resource Control, RRC, layer and includes as said lower portion a Radio Link Control, RLC, protocol layer below the PDCP layer, a Medium Access Control, MAC, protocol layer below the RLC protocol layer, and a Physical, PHY, protocol layer below the MAC protocol layer, characterized in that the intra-stack IP link communicatively couples the gateway node to the RLC protocol layer at the radio node . <EOS>