DMRS Sharing in LTE Downlink Control and Data Signals
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Solution Overview
Problem
In LTE wireless communication systems, efficiently sharing downlink demodulation reference signals (DMRSs) between data and control signals is challenging, especially in single-user MIMO spatial multiplexing scenarios, where DMRSs are not effectively utilized for both DL control and data reception.
Innovation Solution
A communication device and base station system that allocates and transmits DMRSs across multiple time-frequency resources, allowing DMRSs to be shared between DL data and control signals, enabling efficient DMRS utilization through precise time-frequency resource management and SU-MIMO spatial multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DMRSs are allocated separately for DL control signal and DL data, then each signal can be demodulated reliably, but time-frequency resource utilization efficiency deteriorates
Solution Approach 1:
The patent merges the DMRS allocation for DL control signal and DL data into a single shared DMRS resource. The base station transmits one set of DMRS that serves both the control signal and data, eliminating the need for separate DMRS allocations and thereby improving resource utilization efficiency while maintaining demodulation reliability through proper signal separation in time-frequency resources.
Solution Approach 2:
The shared DMRS resource performs multiple functions: it serves as the demodulation reference for both the DL control signal and DL data. This multi-functional approach allows the same DMRS to be utilized across different time-frequency resources, enhancing system efficiency without compromising the reliability of either signal type.
2Productivity
If DMRSs are shared between DL control signal and DL data, then resource utilization efficiency improves, but the complexity of time-frequency resource allocation increases
Solution Approach 1:
The base station determines and signals the shared DMRS resource configuration in advance through higher layer signaling before the actual data transmission. This preliminary configuration includes indicating which DMRS ports are shared and how they map to different time-frequency resources, thereby simplifying the receiver's processing while maintaining efficient resource utilization.
Solution Approach 2:
The system employs feedback mechanisms where the base station signals the DMRS sharing configuration to the terminal device. This feedback loop allows for proper configuration management and ensures that both transmitter and receiver are synchronized on the shared DMRS resource allocation, reducing allocation complexity.
3Productivity
If SU-MIMO spatial multiplexing is used for DL data transmission, then data throughput improves, but DMRS sharing with control signal becomes more difficult
Solution Approach 1:
The patent segments the time-frequency resources into distinct regions for DL control signal and DL data transmission, while sharing the DMRS resource across both regions. The control signal is transmitted in a first time-frequency resource and data in a second time-frequency resource, with both regions utilizing the same DMRS ports for demodulation, thereby enabling SU-MIMO spatial multiplexing with efficient DMRS sharing.
Solution Approach 2:
The system resolves the DMRS sharing complexity by utilizing the time-frequency dimension for separation while sharing the spatial dimension (DMRS ports) for both control and data. This dimensional approach allows multiple signals to coexist without interference while maintaining efficient resource utilization through proper multiplexing.
Data Source
AI summary
A base station (BS) for sharing downlink (DL) demodulation reference signals (DMRSs) between the DL data and the DL control signals comprises a storage device for storing instructions and a processing circuit coupled to the storage device. The processing circuit is configured to execute the instructions stored in the storage device. The instructions comprise transmitting a DL control signal on a first layer in a first time-frequency resource to the communication device; transmitting a DL data, associated with the DL control signal on a second layer in the first time-frequency resource and on the first layer and the second layer in a second time-frequency resource, to the communication device; and transmitting a set of DMRSs for the DL control signal and the DL data to the communication device.