Читать книгу Mobile Communications Systems Development - Rajib Taid - Страница 57

The physical interface defines the electrical characteristic of the physical transmission media being used for the actual transmission and reception of information between a sender and receiver. Consider the physical Cat5 cable or its other variants used in a Local Area Network to transmit and receive upper/lower layers information. Application data received from the upper layers are converted into Ethernet frames. The network interface card (NIC)/Ethernet chipset generates the required electrical signals to transmit the frames through the Cat5/6 physical cable/layer. The NIC/Ethernet driver also knows when to read and write binary data from the physical interface and layer.

Similarly, in the case of a mobile communications system also, various physical transmission interfaces/media are used across the different systems, i.e. GSM to 5G, to transmit either signaling or user traffic between two network elements. Being the GRPS CN, LTE/Evolved Packet Core (EPC) and 5G as an IP network‐based system, the IP transport network is used to transmit and receive information among their network elements. Example s 3.1 and 3.2 below illustrate the typical physical interfaces found in mobile communications systems, from the GSM to the 5G system.