DMRS Pattern Segmentation for MU-MIMO Interference Reduction
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Solution Overview
Problem
In multi-user Multiple Input Multiple Output (MIMO) operations, different reference signal patterns for downlink receiving entities can cause serious inter-layer interference, preventing normal MU-MIMO operation.
Innovation Solution
The method involves mapping demodulation reference signals (DMRS) for different layers on a downlink physical resource block using distinct patterns, with resource elements corresponding to one pattern being punctured on the other layer to reduce interference, allowing for efficient MU-MIMO transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different reference signal patterns are used for different downlink receiving entities in MU-MIMO operation, then channel estimation can be performed for each entity, but inter-layer interference occurs between the reference signals
Solution Approach 1:
The reference signal pattern is segmented into different types (first reference signal pattern and second reference signal pattern) that are assigned to different layers. This segmentation allows the receiving entity to distinguish between reference signals intended for different layers, thereby preventing inter-layer interference while maintaining accurate channel estimation for each layer.
Solution Approach 2:
Different reference signal patterns are applied to different layers based on their specific requirements. The first reference signal pattern is used for layers where the receiving entity needs to estimate the channel, while the second reference signal pattern is used for layers where the transmitting entity performs precoding. This local differentiation ensures that each layer has the appropriate reference signal quality for its function.
2Productivity
If reference signals for multiple layers are transmitted simultaneously, then MIMO data transmission rate increases, but resource element collision causes interference
Solution Approach 1:
The patent introduces a new dimension for resource allocation by defining different reference signal patterns in the time-frequency space. Instead of allocating reference signals only in the frequency domain, the patent uses both time and frequency dimensions to separate reference signals for different layers, thereby avoiding resource element collision while maintaining high MIMO transmission rates.
Solution Approach 2:
The patent introduces an intermediary mechanism (the second reference signal pattern) that mediates between the need for simultaneous multi-layer transmission and the need to avoid interference. This intermediary reference signal pattern allows the transmitting entity to perform precoding without causing interference to the receiving entity's channel estimation, enabling simultaneous multi-layer transmission without resource element collision.
Data Source
AI summary
A wireless communication system, a method, and an apparatus for transmitting a multi-user Multiple Input Multiple Output (MIMO) signal in a wireless communication system for supporting a relay. A method for transmitting a demodulation reference signal (DMRS) for downlink multi-user MIMO transmission, the method including mapping a DMRS for first and second layers on a downlink physical resource block according to first and second DMRS patterns, respectively; and transmitting the downlink physical resource block. In the downlink physical resource block, a resource element corresponding to the second DMRS pattern can be punctured on the first layer and resource element corresponding to the first DMRS pattern can be punctured on the first layer and a resource element corresponding to the first DMRS pattern can be punctured on the second layer.