LTE Uplink Subframe Indication for Flexible Unlicensed TDD
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Solution Overview
Problem
The existing TDD mode in LTE systems using unlicensed spectrums is inflexible in uplink and downlink configurations, leading to low transmission efficiency due to fixed ratios of time slots, which can result in channel resources being snatched by WiFi devices, causing frequent interruptions in downlink data transmission.
Innovation Solution
A method is proposed to dynamically indicate uplink subframes on unlicensed spectrums by determining current and next indication periods, acquiring and transmitting indication signaling in downlink subframes to inform terminals of uplink subframe timing positions, using downlink control information carried by the PDCCH with specific formats and CRC codes, and adjusting uplink and downlink subframe allocations to adapt to changing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fixed TDD uplink and downlink configurations are used on unlicensed spectrum, then system simplicity is maintained, but transmission efficiency deteriorates due to channel resource snatching by WiFi devices causing frequent interruptions
Solution Approach 1:
The patent implements dynamic TDD configuration where the base station can flexibly adjust uplink and downlink subframe allocations based on real-time channel conditions and traffic demands. This is achieved through introducing a dynamic indication mechanism that allows the base station to notify terminals of uplink subframe positions in advance, enabling adaptive resource allocation that improves transmission efficiency while coexisting with WiFi systems on unlicensed spectrum.
2Adaptability or versatility
If dynamic uplink subframe allocation is implemented, then adaptability to changing conditions improves, but system complexity increases due to additional indication signaling mechanisms
Solution Approach 1:
The patent applies preliminary action by notifying terminals of uplink subframe timing positions in advance through downlink control information. This advance notification allows terminals to prepare for uplink transmissions proactively, reducing latency and improving resource utilization. The indication signaling is integrated into existing downlink control channels, minimizing additional system complexity while achieving dynamic adaptability.
3Reliability
If LTE transmits services without sensing rules on unlicensed bands, then service transmission continuity is maintained, but interference to WiFi devices increases
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of a base station-controlled dynamic indication system that mediates between LTE service transmission requirements and WiFi coexistence needs. The base station acts as an intermediary by monitoring channel conditions and dynamically adjusting uplink subframe allocations, thereby reducing interference to WiFi devices while maintaining service transmission continuity through coordinated resource management.
Data Source
AI summary
Provided is a method for indicating an uplink subframe on an unlicensed spectrum, including: determining a current indication period and a next indication period according to a preset period duration; acquiring an indication position preset in the current indication period, where the indication position is a timing position of one or more preset downlink subframes; and when the indication position in the current indication period arrives, transmitting indication signaling in a downlink subframe corresponding to the indication position.