Multi-User Channel Prediction With Per-Slot DMRS Feedback for Mobility
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Solution Overview
Problem
Existing wireless communication systems face challenges in maintaining precoding reliability for high mobility multi-user multi-input/multi-output (MU-MIMO) scenarios due to outdated precoding matrices resulting from infrequent channel state information reference signal transmissions.
Innovation Solution
The network entity transmits demodulated reference signals (DMRSs) using orthogonal precoding parameters on a per-slot basis, receives channel estimation feedback, and updates the precoding matrix and channel prediction accordingly to enhance precoding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If channel state information reference signals are transmitted infrequently, then system overhead is reduced, but precoding reliability deteriorates in high mobility scenarios
Solution Approach 1:
The patent implements per-slot channel estimation feedback where user equipment sends channel state information back to the base station for each time slot. This feedback mechanism enables the base station to update precoding matrices continuously, maintaining precoding reliability in high mobility scenarios without requiring frequent reference signal transmissions, thus reducing system overhead while improving reliability
Solution Approach 2:
The patent performs channel prediction for future time slots based on current and past channel estimates. By predicting channel states in advance, the system prepares precoding matrices before they are needed, ensuring precoding reliability is maintained without requiring real-time reference signal transmissions, thereby reducing overhead while preserving reliability
2Reliability
If channel estimation is performed on a per slot basis, then precoding reliability is improved, but system complexity increases
Solution Approach 1:
The patent enables user equipment to perform self-service channel estimation using demodulation reference signals that are already present in each slot for other purposes. The UE utilizes these existing signals to estimate channel state information and provide feedback, eliminating the need for separate reference signal transmissions and reducing overall system complexity while maintaining per-slot precoding reliability
Solution Approach 2:
The patent makes demodulation reference signals serve multiple functions: their primary function for data demodulation and an additional function for channel state information estimation. This multi-functionality allows per-slot channel estimation without requiring dedicated reference signals, thereby improving precoding reliability while avoiding increased system complexity
3Measurement precision
If multiple DMRS with orthogonal precoding parameters are transmitted, then channel estimation accuracy is improved, but signal overhead increases
Solution Approach 1:
The patent transmits multiple demodulation reference signals with different orthogonal precoding parameters, which can be viewed as creating multiple copies or variations of the reference signal. These copies provide diverse channel information that improves estimation accuracy. The orthogonal nature of the precoding parameters allows the UE to extract independent channel state information from each DMRS, enhancing measurement precision while the systematic reuse of reference signal structures keeps overhead manageable
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A network entity may transmit via a first time slot, a first set of demodulation reference signals (DMRSs) and a second set of DMRSs that may be associated with a set of user equipments (UEs). The network entity may receive from the set of UEs, respective feedback messages indicating respective channel estimation information based on the first set of DMRSs and the second set of DMRSs. The network entity may generate a multi-user multi-input and multi-output (MU-MIMO) channel prediction for a second slot subsequent the first slot, based on the respective feedback messages and generate a MU-MIMO channel precoder associated with the set of UEs based on the MU-MIMO channel prediction. The network entity may transmit, during the second slot, one or more messages to the UEs based on the MU-MIMO channel prediction and the MU-MIMO channel precoder.