LTE interfaces and protocols

LTE is an all IP Network, has a flat architecture, and thus reduces complexity. Each of the radio and core elements present in the network are interconnected by standardized interfaces so that there is interoperability between different vendor products. So the network operators can choose network elements form same or different vendors. Gn interface which was being used in UMTS for the connectivity of SGSN and GGSN will be used in the initial stage of LTE between SGSN and P-GW but this interface will finally get replaced by S3 and S4 interfaces after the software up-gradation of SGSN. Gn, S3 and S4 interfaces use the different versions of the same application protocol i.e. GPRS Tunnelling Protocol (GTP). Some of these interfaces and protocols that are being used in LTE are mentioned in this paper.