Dedicated Reference Signal Design for MU-MIMO Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, especially in LTE-advanced and next-generation mobile communication, the increase in the number of antennas leads to higher reference signal overhead, deteriorating system performance, particularly in multi-user MIMO transmissions where interference management and channel estimation become complex due to the need for multiple reference signals across different cells and users.
Innovation Solution
A method for transmitting and receiving dedicated reference signals (DRS) that allows terminals to identify and receive DRS from both the serving cell and other cells, enabling effective channel estimation and interference management, while minimizing feedback overhead through the use of virtual cell-specific and terminal-specific information, and flexible feedback mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of antennas is increased to support LTE-advanced and multi-user MIMO transmissions, then the system capacity and data transmission rates are improved, but the reference signal overhead increases and system performance deteriorates
Solution Approach 1:
The patent segments the reference signal functionality by introducing separate CSI-RS for channel state information measurement and DM-RS for data demodulation. This segmentation allows each reference signal type to be optimized independently, reducing overall overhead while supporting multiple antennas for improved system capacity.
Solution Approach 2:
The patent makes reference signals universal by designing CSI-RS and DM-RS structures that can support multiple antenna configurations and transmission modes. The reference signal resources are configured to serve multiple purposes including channel estimation, interference measurement, and demodulation across different MIMO scenarios, reducing the need for dedicated signals for each function.
2Quantity of substance
If separate reference signals are used for CSI measurement and data demodulation in LTE-advanced systems, then reference signal overhead is reduced, but the complexity of reference signal configuration and management increases
Solution Approach 1:
The patent introduces dynamic configuration mechanisms where reference signal parameters such as resource allocation, density, and sequence generation are adaptable based on channel conditions, traffic patterns, and MIMO mode requirements. This dynamic approach reduces overhead by adjusting reference signal usage according to actual needs while managing complexity through standardized configuration procedures.
Solution Approach 2:
The patent utilizes parameter changes in reference signal design including cyclic shifts, resource element mappings, and sequence initialization values that can be adjusted to optimize overhead. By changing these parameters based on system state and configuration, the patent reduces reference signal overhead while maintaining manageable complexity through parameter-based control rather than structural complexity.
3Measurement precision
If multiple orthogonal reference signals are transmitted for multiple antennas in multi-user MIMO, then channel estimation accuracy for multiple users is improved, but interference management becomes more complex
Solution Approach 1:
The patent segments user-specific reference signals through orthogonal designs where each user receives dedicated DM-RS resources with unique orthogonal codes or resource allocations. This segmentation enables accurate per-user channel estimation while simplifying interference management by isolating user signals through orthogonal separation rather than requiring complex interference coordination.
Solution Approach 2:
The patent introduces cell-specific reference signals as intermediaries that facilitate multi-user MIMO operations. These CRS serve as common references that enable user equipment to perform channel estimation and interference measurement without requiring direct user-to-user coordination, simplifying the interference management complexity while maintaining accurate channel estimation for multiple simultaneous users.
Data Source
AI summary
Provided are a method of transmitting a dedicated reference signal (DRS), a method of receiving a DRS, and a feedback method of a terminal. The method of transmitting a DRS includes determining a DRS transmitting resource for at least one terminal which is a target of transmission, and transmitting the DRS using the determined transmission resource and notifying the terminal of information about layer used by the terminal. The method of receiving a DRS includes determining a DRS receiving resource, receiving information about layer used by a terminal from a serving cell base station, and receiving the DRS for the terminal using the determined reception resource and the information about layer. Accordingly, a terminal can find the position and sequence of its DRS. In particular, in the case of multi-user multiple input multiple output (MU-MIMO) or joint scheduling, it is possible to prevent or remove signal interference using the DRS of another terminal.