5G BBU TCP MSS Adjustment to Prevent IP Fragmentation
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Solution Overview
Problem
IP fragmentation occurs when application packets between the 5G core (5GC) network and the baseband unit (BBU) exceed the maximum transmission unit (MTU), leading to degraded system performance due to fragmented packet defragmentation.
Innovation Solution
A transmission method and baseband unit for the 5G network system that adjusts the maximum segment size (MSS) value of the transmission control protocol (TCP) during the three-way handshake procedure to prevent IP fragmentation by modifying the MSS value to fit within the MTU, specifically for TCP three-way handshake packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If application packets are encapsulated with GTP and UDP headers, then packet length increases, but IP fragmentation occurs when exceeding MTU
Solution Approach 1:
The patent applies preliminary action by modifying the MSS value during the TCP three-way handshake before actual data transmission begins. The user-plane program intercepts and adjusts the MSS parameter in SYN/SYN-ACK packets to ensure that subsequent application packets, when encapsulated with GTP and UDP headers, will not exceed the MTU limit and cause fragmentation.
Solution Approach 2:
The patent changes the MSS parameter from its default value to a modified value that accounts for the additional GTP and UDP header overhead. This parameter adjustment ensures that the total packet length (application packet + GTP header + UDP header) remains within the MTU limit, preventing IP fragmentation while maintaining transmission reliability.
2Productivity
If IP fragmentation occurs, then packets are broken into multiple smaller packets, but system performance degrades due to defragmentation
Solution Approach 1:
The patent applies preliminary anti-action by preventing IP fragmentation from occurring in the first place through MSS modification during the TCP handshake. This proactive measure eliminates the need for subsequent defragmentation operations, thereby avoiding the time loss and processing overhead that would otherwise degrade system throughput and performance.
3Ease of operation
If original MSS value is used, then TCP connection is established quickly, but application packets exceed MTU and cause fragmentation
Solution Approach 1:
The patent modifies the MSS parameter during the TCP three-way handshake to a value that prevents application packets from exceeding the MTU limit when encapsulated with GTP and UDP headers. This parameter change maintains efficient TCP connection establishment while simultaneously preventing IP fragmentation, resolving the contradiction between connection ease and fragmentation avoidance.
Data Source
AI summary
A transmission method for a baseband unit (BBU) of a 5G network system includes determining, by a user-plane program, a modified maximum segment size (MSS) value of transmission control protocol (TCP) connection for the BBU of the 5G network system; and modifying, by the user-plane program, an original MSS value with the modified MSS value for encapsulation during a TCP three-way handshake procedure; wherein the modified MSS value is related to a packet length of an application packet between the UE and an application (APP) server of the 5G network system.