NR-PDCCH DMRS Transmission for 4-Antenna Diversity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current 5G New Radio (NR) Physical Downlink Control Channel (PDCCH) systems face challenges in achieving high diversity order transmit diversity due to DMRS overhead, limiting their ability to support four transmit antennas and efficiently manage multi-user multiple-input multiple-output (MU-MIMO) transmissions.
Innovation Solution
The implementation of extended transmit diversity schemes, such as space frequency block coding (SFBC) and per-RE precoder cycling, with DMRS placement options like per-REG, per-REG-cluster, and per-RB, along with quasi-colocation reference signals, to enhance channel estimation and interference mitigation in NR-PDCCH, allowing for higher diversity orders and improved spectrum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DMRS overhead is increased to support higher diversity order transmit diversity, then transmit diversity order is improved, but spectrum efficiency deteriorates
Solution Approach 1:
The patent segments the PDCCH transmission into multiple antenna ports (up to 4 antenna ports) with separate DMRS sequences for each port. This segmentation allows the system to achieve higher diversity order by transmitting independent copies of control information through multiple paths, while the DMRS overhead is managed through efficient resource element allocation patterns that minimize interference with data transmission.
Solution Approach 2:
The patent extends the transmit diversity from traditional 2-antenna configurations to 4-antenna configurations by introducing additional spatial dimensions. This is achieved through extended SFBC schemes that map control information across four antenna ports, effectively adding a spatial dimension to the diversity transmission without proportionally increasing DMRS overhead.
2Reliability
If four transmit antennas are supported to achieve higher diversity order, then transmit diversity order is improved, but device complexity increases
Solution Approach 1:
The patent divides the four transmit antenna system into two pairs of antenna ports, where each pair can be independently configured and managed. This segmentation reduces the complexity of channel estimation and signal processing by allowing the system to handle two independent 2x2 MIMO streams rather than a monolithic 4x4 system, thereby reducing device complexity while maintaining high diversity order.
Solution Approach 2:
The patent implements optional 4-antenna support where systems can selectively enable or disable specific antenna ports based on channel conditions and capability negotiations between gNB and UE. This partial action approach allows the system to achieve high diversity order when needed while reducing complexity in scenarios with fewer antennas, providing flexibility to manage device complexity dynamically.
3Productivity
If MU-MIMO transmissions are implemented to increase capacity, then productivity is improved, but interference between users increases
Solution Approach 1:
The patent introduces UE-specific DMRS sequences as intermediary signals that are orthogonal or quasi-orthogonal across different UEs in MU-MIMO transmissions. These DMRS sequences serve as mediators that enable the receiver to distinguish and separate signals from different users, thereby managing user interference while maintaining high system capacity through efficient multi-user resource allocation.
4Measurement precision
If DMRS placement is increased to support channel estimation for multiple antennas, then measurement precision is improved, but overhead increases
Solution Approach 1:
The patent merges the channel estimation function for multiple antenna ports into a unified DMRS structure where reference signals for different ports are multiplexed in the time-frequency grid. This merging allows the system to achieve accurate channel estimation for all four antenna ports while sharing common DMRS resources, thereby reducing total overhead compared to having separate reference signal sets for each antenna port.
Data Source
AI summary
Embodiments of the present disclosure describe methods and apparatuses for physical downlink control channel (PD-CCH) demodulation reference signal (DMRS) transmission and reception.