Preventing Security Key Mismatch in Multi-Band Handovers
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Solution Overview
Problem
In wireless communications networks, particularly during handovers between cells supporting multiple frequency bands, there is a risk of security key mismatch due to uncertainty about the frequency band selection by the target eNB, leading to potential security issues and key calculation challenges for both X2 and S1 handovers.
Innovation Solution
The source eNB provides assistance to the target eNB by selecting and informing the specific frequency band supported by both the target cell and the UE, calculating the security key (KeNB*) based on this selection, and ensuring that the UE and target eNB use the same frequency band for secure handovers, including re-establishment scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the target eNB selects a frequency band independently during handover, then the handover flexibility and adaptability are improved, but security key mismatch occurs due to uncertainty about the frequency band selection
Solution Approach 1:
The source eNB performs preliminary action by determining the frequency band before handover and including it in the handover request message to the target eNB. This allows the target eNB to pre-calculate the security key using the same frequency band information, ensuring key consistency is established before the actual handover occurs, thus preventing security key mismatch while maintaining handover flexibility
Solution Approach 2:
The invention implements feedback by having the source eNB provide the determined frequency band information to the target eNB through the handover request message. This feedback loop ensures both eNBs have consistent frequency band information, allowing them to independently calculate the same security key (KeNB*) without mismatch, resolving the contradiction between independent selection and key consistency
2Adaptability or versatility
If multiple frequency bands are supported and selectable, then the network adaptability and service capability are improved, but the complexity of security key calculation and management increases
Solution Approach 1:
The invention applies local quality by determining the specific frequency band locally at the source eNB based on UE capabilities and network conditions, then using this locally determined band for security key calculation. This localized determination simplifies the overall process by eliminating the need for complex coordination between multiple eNBs regarding frequency band selection, reducing security key calculation complexity while maintaining multiple band support
Solution Approach 2:
The invention changes the parameter transmission approach by including the determined frequency band (EARFCN) as a explicit parameter in the handover request message. This parameter change allows the target eNB to use the exact same frequency band value for key calculation, simplifying the security key management process while supporting multiple frequency bands through the flexibility of parameter selection
3Ease of operation
If the frequency band selection is left to the target eNB, then the operational autonomy is improved, but the risk of security key mismatch and potential security issues increases
Solution Approach 1:
The source eNB performs preliminary action by determining the frequency band before handover and communicating it to the target eNB in advance. This allows the target eNB to maintain operational autonomy in executing the handover while having the necessary frequency band information pre-provided, enabling it to calculate the security key correctly without mismatch risk
Solution Approach 2:
The determined frequency band information acts as an intermediary element that bridges the source eNB and target eNB. By including this frequency band parameter in the handover request message, it mediates the security key calculation process, ensuring both eNBs use the same basis for key generation, thus eliminating security key mismatch risk while preserving target eNB autonomy
Data Source
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AI summary
Systems, methods, apparatuses, and computer program products for security handling in, for example, cells that support multiple frequency band indication are provided. One method includes receiving, for example by a source evolved node B (e NB) configured to communicate with a user equipment, a multiple frequency band indicator (MFBI) list, the multiple frequency band indicator (MFBI) list comprising at least one frequency band number listed in the same order of priority as broadcast by a target e NB. The method may further include selecting one of the at least one frequency band number for use by the source e NB, calculating a security key (KeNB*) using the DL EARFCN belonging to the selected frequency band number with the highest priority that is also supported by the user equipment, and signaling the calculated security key to the target eNB.