Multi-User Multiplexing via User-Specific Reference Signals
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Solution Overview
Problem
Current wireless communication systems, such as LTE Rel-8, are limited in supporting spatial multiplexing for multiple user terminals due to the reliance on cell-specific reference signals, which restricts the number of spatial multiplexing layers to four, preventing efficient utilization of time-frequency resources for more user terminals.
Innovation Solution
A multi-user multiplexing method where a base station uses a precoding matrix to weight and transmit data streams and pilot signals onto physical transmit antennas, allowing for spatial multiplexing between multiple user terminals without relying on cell-specific reference signals, thereby improving the utilization of time-frequency resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cell-specific reference signals (CRS) are used for spatial multiplexing in LTE Rel-8, then the system can support up to four layers of data streams, but the number of user terminals that can be multiplexed is limited to four
Solution Approach 1:
The patent extracts the reference signal function from the cell-specific reference signal (CRS) and implements it through user-specific reference signals (URS). By separating the reference signal functionality from the CRS limitation, the system can support more than four spatial multiplexing layers and multiplex more user terminals without being constrained by the four-layer CRS limitation.
Solution Approach 2:
The patent changes the reference signal parameter from cell-specific (CRS) to user-specific (URS). This parameter change allows each user terminal to have its own reference signal, enabling the system to multiplex more user terminals beyond the four-terminal limit imposed by CRS, while maintaining backward compatibility through configurable switching between CRS and URS modes.
2Productivity
If four layers of data streams are supported through CRS, then spatial multiplexing can be implemented, but time-frequency resource utilization efficiency is insufficient for supporting more user terminals
Solution Approach 1:
The patent implements a dual-mode reference signal system that can universally support both traditional CRS-based spatial multiplexing and the new URS-based multi-user multiplexing. The system can flexibly switch between CRS mode and URS mode, making the reference signal mechanism universally applicable to different multiplexing scenarios and improving overall time-frequency resource utilization efficiency.
Solution Approach 2:
The patent transitions from the traditional single-dimension CRS approach to a multi-dimensional reference signal structure where user-specific reference signals operate in an additional dimension. This allows the system to multiplex user terminals not only through spatial layers but also through user-specific signal dimensions, thereby improving time-frequency resource utilization efficiency while supporting more user terminals.
Data Source
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AI summary
A multi-user multiplexing method, a base station, and a user terminal are disclosed. The method includes: a base station weights, using a precoding matrix, multiple data streams that need to be transmitted to N user terminals to obtain to-be-transmitted data streams mapped onto K physical transmit antennas; weights, using the precoding matrix, a pilot signal that needs to be transmitted to the N user terminals to obtain to-be-transmitted pilot signals mapped onto the K physical transmit antennas; and sends the to-be-transmitted data streams and the to-be-transmitted pilot signals to the N user terminals by using the K physical transmit antennas. The to-be-transmitted data streams and the to-be-transmitted pilot signals are mapped onto different time-frequency resources. N is a positive integer greater than or equal to 2, K is a positive integer, and the precoding matrix is calculated according to characteristics of channels from the K physical transmit antennas to the N user terminals.