QoS Flow Accounting Updates Across 5GS–EPS Handovers
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Solution Overview
Problem
The challenge of updating accounting sessions when a terminal device is handed over between different mobile cellular networks, such as 5GS and EPS, is not adequately addressed in existing systems, leading to inefficiencies in service access control and charging due to differing granularities of accounting session allocation.
Innovation Solution
A communication method where a session management function network element indicates an authentication, authorization, and accounting server to update accounting sessions based on bearer information during handovers, using specific identifiers and messages to manage accounting sessions efficiently for quality of service flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the SMF network element allocates accounting sessions based on PDU session granularity in 5GS, then the accounting session management is simplified, but the precision of service access control and charging is reduced when handed over to EPS
Solution Approach 1:
The patent segments the accounting session management by network type. In 5GS, accounting sessions are allocated at PDU session granularity, while in EPS, they are allocated at bearer granularity. During handover, the system maintains separate accounting session pools for each network type and selectively activates appropriate sessions based on the target network, thus managing complexity through segmentation while preserving control precision.
Solution Approach 2:
The patent implements dynamic accounting session allocation that adapts to the current network type. The SMF network element dynamically selects which accounting session pool to use (5GS PDU session-based or EPS bearer-based) depending on whether the terminal is in 5GS or EPS. This dynamic adaptation ensures the most appropriate granularity is used in each context, maintaining both management simplicity and control precision.
2Measurement precision
If the SMF network element allocates accounting sessions based on bearer granularity in EPS, then the precision of service access control and charging is improved, but the accounting session management complexity increases when handed over to 5GS
Solution Approach 1:
The system segments accounting session management by network type, maintaining separate accounting session pools for 5GS (PDU session-based) and EPS (bearer-based). This segmentation allows each network to use its optimal granularity without the other's complexity, as the SMF selectively activates appropriate sessions based on the current network context.
Solution Approach 2:
The SMF implements dynamic selection of accounting session allocation strategies based on the current network type. When in 5GS, it uses PDU session granularity; when in EPS, it uses bearer granularity. This dynamic behavior resolves the contradiction by adapting the management complexity to match the operational context, ensuring precision is maintained without permanent complexity overhead.
3Adaptability or versatility
If the terminal device is handed over between 5GS and EPS networks, then the network flexibility and service continuity are improved, but the accounting session update complexity and potential service interruption increase
Solution Approach 1:
The patent establishes accounting session pools in advance for both 5GS and EPS network types before handover occurs. The SMF pre-configures appropriate accounting sessions in each pool based on the respective network's granularity requirements. During handover, the system simply activates the pre-prepared sessions in the target network, avoiding complex real-time creation or modification of accounting sessions and thus reducing update complexity.
4Duration of action of stationary object
If the accounting session is not updated during handover between 5GS and EPS, then the service continuity is maintained, but the charging accuracy and service access control deteriorate
Solution Approach 1:
The patent implements a copying mechanism where accounting session information is replicated from the source network to the target network during handover. The SMF creates appropriate accounting sessions in the target network based on the source network's session information, adapting the granularity to match the target network type. This copying approach maintains service continuity while ensuring charging accuracy through proper session establishment in the new network.
Data Source
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AI summary
A communication method and a communication apparatus are provided. The method includes: After a session management function network element establishes, for a terminal device, a protocol data unit session that is in a first network and that includes a first quality of service flow, and when a terminal device is handed over from the first network to a second network, if it is determined to map the first quality of service flow to a first bearer in the second network, the second message that includes an identifier of a first accounting session corresponding to the first quality of service flow and information about the first bearer may be sent to an authentication, authorization, and accounting server, so that the second message indicates the authentication, authorization, and accounting server to update the first accounting session. According to the foregoing process, when the terminal device is handed over from the first network to the second network, the session management function network element indicates the authentication, authorization, and accounting server to update the first accounting session based on the information about the first bearer, so that after the terminal device is handed over to the second network, control such as charging is performed based on information about the first accounting session for a service transmitted by the terminal device by using the first bearer.