ACK/NACK Reporting Decoupling RTT Estimates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inaccurate estimates of round trip time (RTT) in mobile radio communication systems lead to improper acknowledgment or retransmission of data blocks, causing unnecessary retransmissions, wasted bandwidth, and decreased performance due to variance in actual RTT compared to broadcasted RTT.
Innovation Solution
Decoupling RTT from ACK/NACK analysis by using a 'void' message in ACK/NACK reports instead of 'not received' for blocks with no information, allowing independent determination of data blocks to retransmit without relying on RTT estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RTT estimates are used for ACK/NACK analysis, then data transmission efficiency is improved, but accuracy of ACK/NACK reporting deteriorates due to RTT variance
Solution Approach 1:
The patent extracts the RTT estimation mechanism from the ACK/NACK analysis process. Instead of using RTT estimates to determine which data blocks are acknowledged, the system separates the acknowledgment decision (based on bitmap position matching) from the RTT calculation, eliminating the source of inaccuracy while preserving transmission efficiency
Solution Approach 2:
The patent introduces an intermediary mechanism using bitmap position matching as the mediator between transmitted data blocks and acknowledged blocks. The bitmap position serves as an intermediate reference that connects the transmitted sequence numbers with the received acknowledgment status without requiring RTT estimation, thus resolving the contradiction between efficiency and accuracy
2Device complexity
If broadcast RTT is used for all mobile stations, then system complexity is reduced, but reliability of ACK/NACK reporting deteriorates due to RTT variance between cells and over time
Solution Approach 1:
The patent removes the dependency of ACK/NACK reporting on RTT values by extracting the RTT estimation from the acknowledgment process. The bitmap position matching mechanism operates independently of RTT, eliminating the reliability issue caused by broadcast RTT variance while maintaining simple system architecture
Solution Approach 2:
The system uses self-service through automatic bitmap position matching where the acknowledgment process serves itself without external RTT information. The bitmap positions automatically correlate transmitted and acknowledged blocks based on sequence number matching, making the system self-sufficient and reliable without complex RTT management
3Productivity
If RTT estimation is implemented, then communication performance is improved, but loss of time increases due to unnecessary retransmissions
Solution Approach 1:
The patent converts the potential harm of inaccurate RTT estimates into benefit by using the bitmap position matching mechanism. Instead of allowing RTT errors to cause unnecessary retransmissions, the system uses position matching to accurately identify acknowledged blocks, turning the challenge of RTT variance into an opportunity for more reliable acknowledgment reporting that reduces retransmission delays
Data Source
AI summary
A method, node, and system are provided that overcome problems with using inaccurate estimates of a current round trip time RTT for verifying the ACK/NACK information received in an ACK/NACK report, e.g., a piggy-backed ACK/NACK (PAN). This is accomplished by de-coupling the RTT from the ACK/NACK analysis performed in the sending node that receives the ACK/NACK report. As a result, unnecessary re-transmissions are avoided, communication delays are decreased, and spectrum and other system resources are used more efficiently.