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The realization of high data rates in LTE technology over an all IP network means an ever increasing load on packet data networks. 3GPP has defined data offloading as a key solution to cope with this challenge. Data offloading has been a critical area of study in 3GPP Release-10. The 3GPP Evolved Packet Core (EPC) has been defined to be expansive; for example, it is designed to work in conjunction with non-3GPP access networks, femto cells etc., This diversity causes more scenarios to tackle, but it also provides solutions in the ways of offloading data from the EPC. This article is a tutorial on three such mechanisms, namely Local IP Access (LIPA), Selected IP Traffic Offload (SIPTO) and IP Flow Mobility (IFOM). The article starts with an overview of data offloading methods. The basics and key concepts of each method are summarized before giving the requirements, architecture and procedures with high-level message flows. The article ends with a brief evaluation of the mechanisms and references for the reader interested in further reading.
Date of Publication: June 2012