Reducing DMRS Overhead in Small Cell Demodulation
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Solution Overview
Problem
In LTE wireless networks, small cells face challenges in reducing DMRS overhead while maintaining effective channel estimation and interference coordination, especially when operating at the same frequency as macro-cells, due to their low transmit power and limited coverage area.
Innovation Solution
The implementation of alternative DMRS patterns that reduce DMRS density in the time or frequency domain, or both, along with orthogonal DMRS assignments and PRB bundling, allows for reduced overhead and improved interference coordination among small cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DMRS density is maintained at traditional levels in small cells, then channel estimation accuracy is preserved, but DMRS overhead becomes excessive and reduces network throughput
Solution Approach 1:
The patent changes the density parameter of DMRS in the time and/or frequency domain by introducing alternative DMRS patterns with reduced density. This allows the system to maintain adequate channel estimation accuracy while reducing the overhead proportion from 14% to between 4.76% and 9.5%, thereby improving network throughput.
Solution Approach 2:
The patent applies partial action by selectively reducing DMRS density only in specific time-frequency resources where full density is not required for accurate channel estimation. This partial reduction in DMRS overhead achieves the dual benefit of maintaining estimation accuracy while freeing up resources for data transmission.
2Productivity
If DMRS density is reduced in small cells, then DMRS overhead decreases and network throughput improves, but channel estimation accuracy and interference coordination capability deteriorate
Solution Approach 1:
The patent introduces alternative DMRS patterns that change the density parameter of DMRS in time and/or frequency domains. These patterns maintain adequate channel estimation accuracy while reducing overhead to between 4.76% and 9.5%, thereby improving network throughput without sacrificing estimation quality.
Solution Approach 2:
The patent enables dynamic selection among multiple DMRS patterns (including alternative patterns with reduced density and traditional patterns) based on channel conditions, interference levels, and traffic requirements. This dynamic adaptability ensures channel estimation accuracy is maintained when needed while allowing overhead reduction when conditions permit.
3Object-affected harmful factors
If traditional DMRS patterns are used in small cells operating at the same frequency as macro-cells, then interference coordination becomes difficult, but maintaining traditional patterns ensures backward compatibility
Solution Approach 1:
The patent changes the time-frequency distribution parameters of DMRS by introducing alternative patterns with reduced density. This parameter change enables better interference coordination between small cells and macro-cells operating at the same frequency, as the reduced DMRS density creates more flexibility in resource allocation and interference management.
Solution Approach 2:
The patent enables dynamic selection among multiple DMRS patterns based on interference conditions and frequency coordination requirements. This adaptability allows the system to optimize interference coordination between small cells and macro-cells while maintaining backward compatibility through selective pattern usage.
4Productivity
If DMRS overhead is reduced through alternative patterns, then more resources are available for data transmission, but device complexity increases due to pattern selection and configuration
Solution Approach 1:
The patent introduces alternative DMRS patterns with reduced density parameters, freeing up time-frequency resources for data transmission. The standardized pattern definitions and selection mechanisms manage the added complexity while delivering improved data transmission capacity.
Solution Approach 2:
The patent implements dynamic pattern selection based on channel conditions, interference levels, and traffic requirements. This dynamic approach optimizes the balance between overhead reduction and complexity management, enabling the system to use simplified patterns when conditions permit and traditional patterns when needed.
Data Source
AI summary
Described herein is a network element with a processor. The processor is configured to promote transmitting a first physical resource block (PRB) pair that contains a first demodulation reference signal (DMRS) pattern. The processor is further configured to promote transmitting a second PRB pair that contains a second DMRS pattern. The first DMRS pattern is a subset of the second DMRS pattern.