FDD Uplink Duty Cycle Optimization via HARQ Bundling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Frequency Division Duplex (FDD) wireless communication systems face significant performance degradation due to a limited uplink duty cycle, caused by interference between downlink and uplink transmissions, which is exacerbated by asymmetry in physical downlink shared channel and physical uplink control channel hybrid automatic repeat request acknowledgment asymmetry.
Innovation Solution
Implementing various HARQ and scheduling techniques, including configuring user equipments (UEs) with different uplink activity patterns and transmitting bundled acknowledgments, to minimize loss associated with the limited uplink duty cycle, thereby optimizing both downlink and uplink performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FDD system uses traditional uplink transmission method, then system simplicity is maintained, but performance degradation occurs due to limited uplink duty cycle and interference
Solution Approach 1:
The patent segments the uplink transmissions into multiple subframes with different duty cycles. Specifically, it divides uplink transmissions into first uplink transmissions in first subframes with a first duty cycle and second uplink transmissions in second subframes with a second duty cycle. This segmentation allows the system to manage interference by controlling when and how uplink transmissions occur, thereby improving overall system performance while mitigating the harmful effects of limited uplink duty cycle.
2Productivity
If uplink duty cycle is increased to improve throughput, then data transmission efficiency improves, but interference with downlink transmissions increases
Solution Approach 1:
The patent implements periodic action by establishing a pattern where uplink transmissions occur in alternating subframes with different duty cycles. The first uplink transmissions occur in first subframes with a higher duty cycle to maximize throughput during those periods, while second uplink transmissions occur in second subframes with a lower duty cycle to reduce interference. This periodic alternation allows the system to achieve higher overall throughput while managing interference through structured time-domain separation.
3Reliability
If acknowledgment transmissions are frequent to improve reliability, then HARQ performance improves, but uplink duty cycle limitations are exacerbated
Solution Approach 1:
The patent merges multiple acknowledgment transmissions into bundled acknowledgments. Instead of sending separate acknowledgments for each downlink transmission, the system combines multiple HARQ acknowledgments into a single bundled acknowledgment transmitted in one uplink subframe. This merging reduces the frequency and number of uplink transmissions required, thereby maintaining HARQ reliability while working within the constraints of limited uplink duty cycle.
Data Source
AI summary
Acknowledgment bundling has been defined for Long Term Evolution (LTE) Time Division Duplex (TDD) systems due to asymmetric DL/UL partitioning. In the case of Frequency Division Duplex (FDD) with a limited uplink (UL) duty cycle, there may be asymmetry associated with a downlink transmission and an associated uplink acknowledgment. For example, there may be a physical downlink shared channel (PDSCH) and a physical uplink control channel (PUCCH) hybrid automatic repeat request acknowledgment (HARQ-ACK) asymmetry. Interference between downlink and uplink transmissions may be a factor contributing to the limited UL duty cycle in an FDD system. For an FDD system having a limited mobile transmission duty cycle, both DL and UL performance may be significantly degraded without proper mitigation techniques. According to certain embodiments of the present disclosure, various HARQ and scheduling techniques may be utilized for minimizing loss due to the limited UL duty cycle.