Enhancing the Robustness of LTE Systems: Analysis and Evolution of the Cell Selection Process

The commercial success of LTE makes it the primary standard for 4G cellular technology, and its evolution paves the path for 5G technology. Furthermore, LTE Unlicensed has been proposed recently to allow cellular network operators to offload some of their data traffic to LTE component carriers operating in the unlicensed band. Hence, it is critical to ensure that the LTE system performs effectively even in harsh signaling environments in both licensed and unlicensed spectrum. This article analyzes the effect of different levels of RF spoofing applied to LTE. RF spoofing affects LTE devices during the initial cell selection process, where a strong nearby cell can impede access to a serving LTE network. This is a serious threat and can be caused unintentionally, in the case of dense and uncoordinated LTE deployment in unlicensed spectrum, or intentionally, where an adversary sets up a fake LTE cell in either licensed or unlicensed LTE spectrum. This article analyzes and experimentally demonstrates the severity of these threats for the evolution of LTE and proposes effective mitigation techniques to prevent denial of service. These mitigation techniques improve the cell selection process at the LTE user equipment, and are backward-compatible with existing LTE networks. We recommend that these modifications be enforced in future releases for increasing the availability and scalability of LTE.