HD-FDD Subframe Scheduling for eMTC Peak Data Rates
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Solution Overview
Problem
Current LTE systems face limitations in maximum data rates for low-cost, low-data-rate devices using half duplex frequency division duplex (HD-FDD) communication, particularly in enhanced machine type communication (eMTC), due to restrictive subframe configurations that limit simultaneous uplink and downlink capabilities.
Innovation Solution
Implementing self subframe scheduling for the physical downlink shared channel (PDSCH) and bundling or multiplexing acknowledgement (ACK/NACK) for multiple hybrid automatic repeat request (HARQ) processes within a single subframe to enhance data transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional subframe configurations are used for HD-FDD communication, then device complexity is reduced and ease of operation is improved, but peak data rate is limited to 300 kbps
Solution Approach 1:
The patent implements dynamic subframe scheduling where the network can flexibly configure uplink and downlink subframes based on traffic demands. This allows the system to adaptively optimize data rates by dynamically adjusting the timing relationships between uplink and downlink transmissions, rather than using fixed static configurations.
Solution Approach 2:
The patent introduces additional timing dimensions by allowing multiple HARQ processes to operate with different timing relationships. By bundling or multiplexing ACK/NACK feedback across multiple HARQ processes within extended timing windows, the system effectively adds temporal dimensionality to the scheduling flexibility, enabling higher aggregate data rates.
2Productivity
If multiple HARQ processes are implemented to increase data rates, then productivity is improved, but acknowledgement handling complexity increases
Solution Approach 1:
The patent merges multiple ACK/NACK feedback signals for different HARQ processes into bundled feedback transmissions. Instead of requiring separate feedback channels for each HARQ process, the system combines acknowledgments across multiple processes into unified feedback messages, reducing the overall feedback signaling complexity while maintaining support for multiple parallel HARQ operations.
Solution Approach 2:
The patent creates a universal feedback mechanism that can handle both individual and bundled ACK/NACK feedback across multiple HARQ processes. The same feedback channel and processing logic can accommodate varying numbers of HARQ processes and different bundling configurations, providing a multi-functional solution that scales with data rate requirements without proportionally increasing complexity.
3Adaptability or versatility
If self subframe scheduling is implemented for PDSCH, then data transmission flexibility is improved, but timing synchronization requirements become more stringent
Solution Approach 1:
The patent implements feedback mechanisms where the receiving device sends timing adjustment information back to the transmitting device based on received signals. This feedback loop allows the system to maintain precise timing synchronization even as scheduling flexibility increases, as the feedback continuously corrects any timing drift that may occur with dynamic subframe configurations.
Solution Approach 2:
The patent enables self-subframe scheduling where the system autonomously adjusts timing relationships based on pre-configured parameters and automatic timing advance mechanisms. The scheduling entity can independently manage timing synchronization without requiring constant external intervention, maintaining precision while providing scheduling flexibility through self-adjusting timing mechanisms.
Data Source
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AI summary
The apparatus improves HD-FDD data transmission rates, e.g., for eMTC by using a self subframe scheduling PDSCH that overlaps a M-PDCCH transmission in time. The apparatus may communicate using ACK(s)/NACK(s) for multiple HARQs that are bundled and/or multiplexed within a subframe in order to increase a number of HARQs.