eMBB and URLLC Data Transmission with RLC NACK Control
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Solution Overview
Problem
Existing data transmission control systems in telecom systems face challenges in achieving very high reliability, leading to increased latency, failure rates, and packet delays beyond the allowed packet delay budget due to inefficient HARQ retransmission processes.
Innovation Solution
Implementing improved Outer Loop Link Adaptation (OLLA) methods that selectively adjust Signal-to-Interference-and-Noise Ratio (SINR) for specific Hybrid Automatic Repeat Request (HARQ) processes based on real-time feedback and proactive retransmission decisions, combined with PDCP duplication for enhanced reliability and resource optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional HARQ retransmission processes are used to ensure high reliability, then packet delivery reliability is maintained, but latency increases and packets exceed their allowed delay budgets
Solution Approach 1:
The system performs preliminary actions by proactively retransmitting packets before the allowed delay budget is exhausted. The OLLA method adjusts SINR targets and triggers retransmissions in advance based on predicted channel conditions and packet age, preventing packets from exceeding their delay budgets while maintaining reliability.
Solution Approach 2:
The system dynamically adjusts SINR targets and retransmission timing based on real-time channel conditions and packet characteristics. The OLLA method continuously monitors channel quality indicators and modifies transmission parameters adaptively, allowing the system to optimize between reliability and latency for each packet based on current conditions.
2Reliability
If conservative transmission rates are used to ensure high reliability, then packet error rate is reduced, but data transmission throughput decreases
Solution Approach 1:
The system changes transmission parameters dynamically by adjusting SINR targets based on packet age and channel conditions. The OLLA method modifies the SINR target parameter to balance reliability and throughput: using higher SINR targets for critical packets requiring high reliability, and lower SINR targets for less time-sensitive packets to maximize throughput.
Solution Approach 2:
The system dynamically adjusts transmission rates and SINR targets based on real-time feedback from channel quality indicators and packet delivery status. This adaptive approach allows the system to optimize the trade-off between packet error rate and throughput by continuously adjusting parameters rather than using fixed conservative rates.
3Productivity
If multiple HARQ processes are used to increase throughput, then data transmission rate improves, but complexity of HARQ management increases
Solution Approach 1:
The system applies different quality levels of HARQ management to different processes based on their needs. The OLLA method selectively applies sophisticated SINR adjustment and proactive retransmission to critical packets and processes, while using simpler management for less time-sensitive traffic, optimizing the balance between throughput and management complexity.
Solution Approach 2:
The system uses feedback from channel quality indicators and packet delivery status to intelligently manage multiple HARQ processes. The OLLA method leverages this feedback to coordinate retransmissions across multiple processes, reducing management overhead by making informed decisions based on actual channel conditions rather than uniformly managing all processes with the same complexity.
4Productivity
If aggressive SINR adjustments are made to improve throughput, then data transmission rate increases, but reliability decreases and failure rates increase
Solution Approach 1:
The system dynamically adjusts SINR targets based on real-time feedback from channel quality indicators and packet delivery status. The OLLA method continuously monitors the effectiveness of SINR adjustments and adapts the adjustment aggressiveness accordingly, preventing excessive aggressiveness that would increase failure rates while still achieving throughput improvements.
Solution Approach 2:
The system uses feedback loops to monitor packet delivery success and channel conditions, adjusting SINR targets accordingly. The OLLA method incorporates feedback from HARQ acknowledgments and channel quality measurements to modulate the aggressiveness of SINR adjustments, ensuring that throughput improvements do not come at the cost of excessive failure rates.
Data Source
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AI summary
A system and method for optimizing data transmission rates in telecom systems requiring very high reliability that accounts for retransmissions of data and corresponding HARQ feedback and using HARQ retransmission to: avoid packets being delayed beyond their allowed PDB for associated radio bearers, avoid increasing failure rate, and avoids increasing latency due to the stop and wait protocol employed for HARQ retransmission, by transmitting NACK via RLC protocol avoiding multiple retransmissions on receiving a HARQ NACK for a selected HARQ process.