Multi-RE DMRS Configuration for 5G NR Uplink Capacity
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Solution Overview
Problem
In 5G NR systems, the uplink transmission capacity is limited due to neighboring cell interference in macro-micro cell scenarios, especially when a macro site and a micro site use different uplink-downlink slot configurations, leading to low data transmission capacity and inability to meet uplink requirements.
Innovation Solution
Enhance uplink transmission capacity by configuring DMRS symbols to occupy more than 2 resource elements consecutively in the frequency domain and adjust symbol positions to overlap with PDCCH and PDSCH resources, allowing for increased DMRS ports and improved interference suppression using Wiener filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single-symbol DMRS is configured for the UE, then the device complexity is reduced and ease of operation is improved, but the uplink transmission capacity is limited to a maximum of six DMRS ports
Solution Approach 1:
The patent transitions from a single-symbol DMRS configuration to a multi-symbol DMRS configuration, adding a time dimension to the DMRS structure. This allows multiple DMRS ports to be supported across multiple symbols, increasing uplink transmission capacity from 6 to 12 ports while maintaining operational simplicity through standardized configuration procedures.
2Quantity of substance
If the DMRS symbol is configured to occupy more than 2 resource elements in frequency domain, then the uplink transmission capacity increases, but the device complexity increases
Solution Approach 1:
The patent introduces dynamic configurability of DMRS parameters including the number of symbols, resource elements per symbol, and CDM groups. The network can dynamically adjust these parameters based on channel conditions and traffic requirements, allowing the system to optimize between transmission capacity and device complexity in real-time.
Solution Approach 2:
The patent changes key parameters of the DMRS configuration including increasing the number of symbols from 1 to multiple symbols, increasing resource elements per symbol from 2 to more than 2, and configuring multiple CDM groups. These parameter changes enable support for up to 12 DMRS ports while managing device complexity through standardized parameter sets.
3Adaptability or versatility
If macro site and micro site use different uplink-downlink slot configurations, then the adaptability to different cell requirements is improved, but neighboring cell interference increases
Solution Approach 1:
The patent converts the harmful neighboring cell interference into a beneficial measurement opportunity. By configuring DMRS symbols to overlap with PDCCH and PDSCH resources in time-frequency domain, the system uses the interference-containing DMRS signals to measure and estimate the interference covariance matrix, which is then used for interference suppression through Wiener filtering.
Solution Approach 2:
The patent introduces DMRS symbols as an intermediary element that serves dual purposes: they act as reference signals for channel estimation and simultaneously serve as measurement signals for interference estimation. The DMRS configuration bridges the gap between different cell configurations by providing a common reference that can be measured even in the presence of inter-cell interference.
4Productivity
If the uplink transmission capacity is increased to support more data streams, then the productivity is improved, but the peak throughput over air interface is limited by interference suppression capability
Solution Approach 1:
The patent implements a feedback mechanism where the network device measures the interference covariance matrix based on DMRS signals from multiple UE, then uses this measured interference information to perform Wiener filtering for interference suppression. This feedback loop continuously adapts the interference suppression capability to current channel conditions, enabling reliable high-throughput transmission.
Data Source
AI summary
This application provides a communication method and apparatus, so that a first network device can configure a terminal device to send a demodulation reference signal symbol in a first different-configuration slot. A quantity of consecutive resource elements occupied by each demodulation reference signal code division multiplexing group included in a demodulation reference signal symbol is greater than 2. Therefore, a quantity of demodulation reference signal ports supported by each demodulation reference signal code division multiplexing group is greater than 2, so that an uplink communication capacity of the terminal in the different-configuration slot can be increased when a quantity of demodulation reference signal code division multiplexing groups in each demodulation reference signal symbol remains unchanged, to meet an uplink transmission requirement of the terminal device.