Data-Plane and Control-Plane Functions in Base Stations and Mobile Stations

Figure below shows the user data processing path at the BS and MS. As shown in the figure, the user data traverses the path from network layer to physical layer and vice versa. In the transmitter side, a network layer packet is processed by the convergence sub-layer, the ARQ function (if enabled), the fragmentation/packing function, and the MAC PDU formation function, to form the MAC PDU to be sent to the physical layer for processing. In the receiver side, a physical layer SDU is processed by MAC PDU formation function, the fragmentation/packing function, the ARQ function (if enabled), and the convergence sub-layer function, to form the network layer packets. The control primitives between the MAC CPS functions and between the MAC CPS and PHY that are related to the processing of user traffic data are also shown below

Signal flow graph in data- and control-planes

The control-plane signaling and processing flow graph at the BS and the MS. In the transmitter side, the flow of control primitives from control-plane functions to data-plane functions and processing of control-plane signals by data-plane functions in order to construct MAC management messages and MAC header/sub-headers, to be transmitted over the air interface, are illustrated. In the receiver side, the arrows show the processing of the MAC control messages through data-plane functions and the reception of the corresponding control-plane signals by control-plane functions. The dotted arrows show the control primitives between MAC CPS functions and between MAC CPS and physical layer functions that are related to the processing of control-plane signaling. The control primitives to/from M-SAP/C-SAP define the network related functionalities, such as inter-BS interference management, inter/intra RAT mobility management, etc., as well as management-related functionalities, such as location management, system configuration, etc.