RB/PRG-Level Precoder Cycling with Virtual DMRS Ports for MIMO Diversity
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in diversity schemes for open-loop MIMO transmissions, particularly in 5G NR networks, where precoder cycling methods either compromise spectral efficiency or increase complexity, and existing precoder schemes are not consistent with DMRS transmission.
Innovation Solution
A diversity scheme using non-transparent RB or PRG level precoder cycling based on virtual DMRS ports, where a precoding matrix with sub-matrices for antenna groups is applied to both data and DMRS, ensuring orthogonality across frequency domain resource units, allowing for efficient channel estimation and demodulation without increasing actual DMRS ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precoder cycling is applied to improve diversity in open-loop MIMO transmissions, then reliability is improved, but device complexity increases
Solution Approach 1:
The precoding matrix is segmented into multiple sub-matrices, each corresponding to a different antenna group. Each sub-matrix can be independently cycled through different precoding options, allowing diversity to be achieved at the sub-matrix level rather than requiring full matrix cycling. This segmentation reduces the overall complexity while maintaining diversity benefits across multiple antenna groups.
Solution Approach 2:
Different sub-matrices of the precoding matrix are assigned different local qualities or characteristics. Specifically, the phase of each subsequent sub-matrix for each subsequent antenna group is shifted to be orthogonal across frequency domain resource units. This local differentiation enables diversity without requiring complex global precoder changes.
2Productivity
If existing precoder schemes are used, then spectral efficiency is maintained, but consistency with DMRS transmission is compromised
Solution Approach 1:
The precoding matrix structure is designed to serve multiple functions simultaneously. The same precoding matrix with phase-shifted sub-matrices is applied to both the data signal and the DMRS. This universal application ensures consistency between data and reference signal transmission while maintaining spectral efficiency through efficient resource utilization.
3Measurement precision
If actual DMRS ports are increased to improve channel estimation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Instead of increasing the number of actual DMRS ports, the system creates virtual DMRS ports through phase-shifting existing DMRS signals. Each antenna group's DMRS is copied with a different phase shift corresponding to its sub-matrix, creating orthogonal virtual ports that improve channel estimation precision without adding physical DMRS ports or associated complexity.
Data Source
AI summary
This disclosure provides systems, methods and apparatuses for transmissions with non-transparent precoder cycling. A network node generates a precoding matrix including a number of sub-matrices equal to a number of antenna groups. A first sub-matrix for a first antenna group is the same for each frequency domain resource unit of a frequency domain resource group. A phase of each subsequent sub-matrix for each subsequent antenna group is shifted to be orthogonal for each frequency domain resource unit. The network node applies the precoding matrix to both a data signal and a demodulation reference signal (DMRS) of a transmission for each frequency domain resource unit of the frequency domain resource group and transmits the precoded transmission via the antenna groups. A UE receives the transmission having non-transparent precoder cycling, estimates a channel of the transmission based on the precoding matrix, and demodulates the data signal based on the estimated channel.