LTE Handover Key Uniqueness via Frequency-Aware Generation
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Solution Overview
Problem
In the LTE system, ensuring the uniqueness of an intermediate key during handover preparation processes across cells of different frequencies is challenging, as cells with different frequencies may share the same PCI, compromising security.
Innovation Solution
A mobile communication method that generates an intermediate key by inputting a base station key, identification information of the handover-target cell, and frequency identification information into a first function, and transmits this key to the handover-target radio base station to generate a base station key necessary for communication, ensuring key uniqueness across multiple cells regardless of frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PCI binding is used for handover preparation across cells of different frequencies, then key uniqueness cannot be ensured, but if frequency identification is added, then key security is improved
Solution Approach 1:
The patent transitions from using only PCI (one-dimensional identifier) to using PCI combined with frequency identification (two-dimensional identifier space). This dimensional expansion ensures that keys generated for handover preparation are unique even across different frequencies, resolving the security vulnerability while maintaining manageable complexity through structured parameter organization.
2Reliability
If intermediate key is generated using only PCI, then generation process is simple, but security is compromised across different frequencies, if frequency ID is included, then security is improved but processing complexity increases
Solution Approach 1:
The patent modifies the input parameters of the key derivation function by adding frequency identification to the existing PCI parameter. This parameter change transforms the key generation process from frequency-agnostic to frequency-aware, ensuring that each frequency band generates distinct intermediate keys for handover preparation, thereby improving security without requiring fundamental process changes.
Data Source
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AI summary
A mobile communication method according to the present invention includes steps of: generating, at a HO-source radio base station, an intermediate key (KeNB*), by inputting, into a first function KDF (*) , a base station key (KeNB), identification information (PCI) of a HO-target cell, and identification information (ARFCN) of a frequency for the HO-target cell; and transmitting, from the HO-source radio base station to a HO-target radio base station, the intermediate key (KeNB*), in the HO process; and generating, at the HO-target radio base station, a base station key (KeNB) on the basis of the intermediate key (KeNB*) in the HO process.