User Equipment PDCP Variable Management for 5G MBS Reliability
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Solution Overview
Problem
Current 5G mobile communication systems face challenges in providing enhanced multicast broadcast services, particularly in managing PDCP packet sequence numbers and hyper frame numbers, which affect decoding and data transmission reliability during handovers and session interruptions.
Innovation Solution
The proposed communication control method involves generating an inferred hyper frame number for decoding PDCP packets, updating PDCP variables in response to received packets, and managing these variables to ensure continuity and reliability during handovers and session changes, using techniques such as initializing or holding PDCP variables based on notifications from the base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP variables are initialized during handover or session interruption, then data transmission reliability is improved, but decoding continuity is degraded
Solution Approach 1:
The system performs preliminary actions by notifying the UE in advance whether PDCP variables should be initialized or held before handover or session interruption occurs. This allows the UE to prepare the appropriate PDCP variable management strategy ahead of time, ensuring both reliability and continuity are maintained without conflict
Solution Approach 2:
The PDCP variable management approach is made dynamic by allowing the system to switch between initialization and holding modes based on real-time conditions. The base station can dynamically indicate which approach to use via notification messages, enabling adaptive response to different handover scenarios and session states
2Stability of the object's composition
If PDCP variables are held during handover, then decoding continuity is improved, but data transmission reliability is degraded
Solution Approach 1:
The base station performs preliminary assessment and notification about whether PDCP variables should be held or initialized before handover occurs. This advance indication allows the UE to configure the appropriate strategy, ensuring that holding variables only happens when it won't compromise reliability
Solution Approach 2:
The system implements feedback mechanisms where the base station monitors session status and handover conditions, then provides feedback indications to the UE about PDCP variable management. This closed-loop control ensures that variable holding decisions are based on current system state and reliability requirements
3Reliability
If PDCP packets are encrypted using count value including HFN, then security is improved, but decoding complexity is degraded
Solution Approach 1:
The system performs preliminary inference of the HFN value before decryption is needed. By calculating the inferred HFN in advance based on available information (PDCP sequence numbers, session state), the system reduces the complexity of the actual decoding process while maintaining security through proper count value construction
Solution Approach 2:
The inferred HFN acts as an intermediary that bridges the security requirement (using HFN in count value) and the complexity problem. Instead of directly using the actual HFN which may be unknown, the system uses an inferred value that can be calculated from available data, simplifying the decryption process while maintaining security integrity
Data Source
AI summary
A communication control method according to a first aspect is a method performed by a user equipment in a mobile communication system for providing a multicast broadcast service (MBS) from a base station to the user equipment. The communication control method includes receiving, from the base station, a PDCP packet encrypted by using a count value including a PDCP sequence number and a hyper frame number and transmitted in an MBS session; generating an inferred hyper frame number by inferring the hyper frame number; attempting decoding of the PDCP packet by using an inferred count value including the PDCP sequence number included in the PDCP packet received and the inferred hyper frame number; and determining the inferred hyper frame number as a valid hyper frame number when the decoding is successful.