DMRS Precoding for MU-MIMO Channel Estimation
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Solution Overview
Problem
Current MIMO systems face challenges in channel estimation, particularly in Multi-User MIMO, due to limited capacity of SRS and the need to accurately determine uplink channels for multiple UEs, which affects system throughput and beamforming weights.
Innovation Solution
A method where a network device transmits instructions to terminal devices to precode DeModulation Reference Signals (DMRSs) using linearly independent precoders, allowing the network device to estimate an equivalent channel and determine the uplink channel based on the precoded DMRSs received, enabling improved channel estimation and potentially downlink channel determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Sounding Reference Signal (SRS) is used for channel estimation in MU-MIMO systems, then channel information can be obtained, but the SRS capacity is limited which restricts the number of UEs that can be grouped
Solution Approach 1:
The patent changes the type of reference signal from SRS to DMRS and modifies the precoding approach by using multiple linearly independent precoders. This parameter change allows the system to overcome SRS capacity limitations and group more UEs for MU-MIMO operations, thereby improving system throughput
Solution Approach 2:
The patent segments the channel estimation process by using multiple linearly independent precoders (N precoders) to estimate multiple equivalent channels. This segmentation allows the network device to obtain channel information for multiple UEs simultaneously, increasing the number of UEs that can be grouped while maintaining high system throughput
2Measurement precision
If precoded DMRS are used for channel estimation, then equivalent channel can be estimated, but the uplink channel determination becomes more complex
Solution Approach 1:
The patent introduces equivalent channels as intermediary variables that simplify the relationship between precoded DMRS and the uplink channel. By estimating equivalent channels first and then deriving the uplink channel from these intermediaries, the patent maintains measurement precision while reducing processing complexity through the use of linearly independent precoders
3Quantity of substance
If multiple linearly independent precoders are used for DMRS precoding, then more equivalent channels can be estimated, but the instruction transmission and processing overhead increases
Solution Approach 1:
The patent changes the precoding parameter by using linearly independent precoders instead of conventional precoding. This parameter change allows the system to estimate multiple equivalent channels simultaneously while minimizing control information overhead, as the linear independence property enables efficient representation of multiple channels
Solution Approach 2:
The patent uses N linearly independent precoders where N can be larger than the minimum required, providing excess precoding capacity. This excessive action ensures that sufficient equivalent channels are estimated for all grouped UEs while the linear independence property prevents proportional increase in information overhead
Data Source
AI summary
The present disclosure provides a method (100) in a network device for channel estimation. The method (100) includes: transmitting (110) to a terminal device an instruction to precode each of a number, L, of DeModulation Reference Signals, DMRSs, using a number, N, of linearly independent precoders, respectively; receiving (120) from the terminal device L*N precoded DMRSs; estimating (130) an equivalent channel associated with an uplink channel from the terminal device to the network device based on one or more of the L*N precoded DMRSs; and determining (140) the uplink channel from the equivalent channel based on the N precoders.