Single Sequence Number Retransmission in 5G Dual Connectivity
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Solution Overview
Problem
In 5G communication systems, the overhead of headers increases due to separate sequence numbers (SNs) used for handover and retransmission, leading to inefficiencies in packet retransmission processes, particularly in dual connectivity scenarios where X2 delays cause prolonged delay times.
Innovation Solution
A method utilizing a single sequence number (SN) for retransmission, where a receiver allocates a single SN to packets and uses a reordering timer to request retransmissions based on a record message, minimizing delay by identifying non-received packets across multiple base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate sequence numbers (SNs) are used for handover and retransmission, then reliability of packet delivery is improved, but header overhead increases
Solution Approach 1:
The patent combines separate sequence numbers for handover and retransmission into a single unified sequence number system. The receiver uses one SN to manage both handover operations and retransmission requests, eliminating the need for separate SN fields in packet headers and thereby reducing header overhead while maintaining delivery reliability through integrated packet tracking and retransmission management.
2Productivity
If retransmission requests are sent immediately upon packet loss detection, then productivity is improved, but delay time increases due to X2 interface delays in dual connectivity
Solution Approach 1:
The patent implements a reordering timer that is started when packets are received out of order or lost. Instead of immediately requesting retransmission upon detecting a gap, the system waits for the timer to expire, allowing potential late-arriving packets to be received first. This preliminary waiting action prevents premature retransmission requests and avoids unnecessary X2 interface delays, thereby improving overall retransmission efficiency while reducing delay time.
3Quantity of substance
If a single SN is used for retransmission, then header overhead is reduced, but difficulty of detecting and measuring packet status increases
Solution Approach 1:
The patent segments the packet status tracking function by introducing a reordering timer mechanism that operates independently from the sequence number itself. The single SN is used for identification, while the timer and associated reordering logic separately handle the detection of packet loss and out-of-order delivery. This segmentation allows the system to maintain simple headers with a single SN while preserving robust packet status detection capabilities through the timer-based reordering process.
Data Source
AI summary
A pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates beyond 4th-generation (4G) communication system such as long term evolution (LTE) is provided. A method of a receiver is provided. The method includes receiving packets to which a single SN is allocated, starting a reordering timer if there is a non-received packet, and requesting a retransmission of the non-received packet among the packets transmitted from a transmitter based on a received record message, if the reordering timer expires.