LTE Security Mode Synchronization via Sequence Number Comparison
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Solution Overview
Problem
In 3GPP Long Term Evolution (LTE) networks, wireless communication devices (UEs) often fail to correctly interpret security mode messages, leading to unsynchronization with the network, as they either misinterpret ciphered messages as un-ciphered or perform incorrect operations due to unactivated security modes.
Innovation Solution
A method is implemented in wireless communication devices to manage received messages by comparing sequence numbers and timestamps, sending security mode complete or failure messages, and applying or ignoring security based on these messages, ensuring synchronization with the LTE network by correctly identifying and handling ciphered or un-ciphered data segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE activates security mode in response to a security mode command message, then security protection is improved, but the risk of misinterpretation and synchronization loss increases when the security mode activation fails
Solution Approach 1:
The patent implements a feedback mechanism where the UE sends a security mode complete or failure message back to the network in response to receiving a security mode command. This feedback allows the network to understand the UE's security mode status and take appropriate actions to maintain synchronization, resolving the contradiction by providing a communication loop that prevents information loss when security activation fails
Solution Approach 2:
The patent applies preliminary action by having the UE determine whether to activate security mode before actually processing subsequent messages. The UE makes a preliminary decision about security mode activation based on the security mode command, and only then proceeds to cipher or uncipher messages accordingly. This prevents misinterpretation by establishing the security state before message processing occurs
2Ease of operation
If the UE does not activate security mode in response to a security mode command message, then message interpretation simplicity is improved, but synchronization with the network deteriorates
Solution Approach 1:
The feedback mechanism ensures that when the UE does not activate security mode, the network is informed through the security mode failure message. This allows the network to maintain synchronization by understanding that the UE is operating in unciphered mode, preventing the deterioration of network synchronization despite the simplified message interpretation
3Adaptability or versatility
If the UE receives ciphered messages without activated security mode, then message reception capability is improved, but message interpretation accuracy deteriorates due to misinterpretation as un-ciphered messages
Solution Approach 1:
The UE performs a preliminary determination of whether security mode is activated before interpreting received messages. This preliminary action ensures that ciphered messages are only processed as ciphered when the security mode is actually activated, preventing misinterpretation while maintaining the ability to receive all types of messages
Solution Approach 2:
The feedback message sent to the network provides information about the UE's security mode status, enabling the network to send appropriate types of messages (ciphered or unciphered) that match the UE's current state, thereby ensuring accurate message interpretation while maintaining reception capability
Data Source
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AI summary
A method of implementing security in a wireless communication device (108) comprises receiving (300), at the device (108), a security mode command for activating a security mode in the device and storing a sequence number of the received security mode command. A security mode complete or failure message is sent (302) based on whether a security mode is activated in the device. An acknowledgement of the security mode complete or failure message is received (304) and a timestamp of the acknowledgement is stored. On receiving a PDU, sequence numbers and timestamps of segments of the received PDU are compared (306) with the stored sequence number and timestamp of the acknowledgement. The received PDU segments are managed (308) in response to the comparisons, and the sending of the security mode complete or security mode failure message. A wireless communication device is also disclosed.