Base Station Pre-Coding for Open-Loop and Closed-Loop User Multiplexing
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Solution Overview
Problem
Current wireless communication systems face challenges in providing high-quality services to high-speed users due to difficulties in obtaining real-time Channel State Information (CSI) and inefficient use of frequency spectrum, especially when the number of antennas exceeds the number of users and interference processing is inadequate.
Innovation Solution
The method involves obtaining and processing Channel State Information (CSI) of both Line of Sight (LOS) and closed-loop signals to enable simultaneous communication with open-loop and closed-loop users, using pre-coding calculations to adapt to changing antenna configurations and improve spectrum utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the BS uses only open-loop SDMA for high-speed users, then the system can serve high-speed users, but the frequency spectrum utilization rate is low and system efficiency is poor
Solution Approach 1:
The patent merges open-loop and closed-loop user services into a unified transmission framework. The BS performs pre-coding calculation using both open-loop CSI (for high-speed users) and closed-loop CSI (for low-speed users), allowing simultaneous service to both user types on the same frequency resources, thereby improving spectrum utilization and system efficiency
Solution Approach 2:
The pre-coding mechanism is designed to be universal, serving both open-loop and closed-loop users through a unified transmission structure. The BS adapts the pre-coding based on the user type and channel conditions, making the system multi-functional in handling diverse user requirements while maintaining high spectrum efficiency
2Reliability
If the BS uses only closed-loop pre-coding for low-speed users, then high-quality service can be provided, but the system cannot effectively serve high-speed users with fast CSI changes
Solution Approach 1:
The system dynamically adapts the pre-coding strategy based on user type and channel conditions. For closed-loop users with slow CSI changes, the system uses traditional pre-coding for high reliability. For open-loop users with fast CSI changes, the system adjusts to use open-loop CSI without requiring real-time feedback, thereby maintaining adaptability to different user scenarios while ensuring service quality
Solution Approach 2:
The patent changes the CSI parameter usage based on user type: closed-loop users use feedback-based CSI for accurate pre-coding, while open-loop users use downlink reference signal-based CSI estimation. This parameter adaptation allows the system to maintain reliability for closed-loop users while becoming versatile enough to serve open-loop users effectively
3Reliability
If the BS has more antennas than users, then the system can provide spatial diversity, but the system efficiency and spectrum utilization decrease
Solution Approach 1:
The patent segments the antenna resources and user services into different functional groups. The BS divides the antenna array into multiple groups that can serve different user types simultaneously, with each group optimized for specific user requirements. This segmentation allows efficient utilization of the antenna resources while maintaining spatial diversity benefits
4Device complexity
If the receiving end processes interference between users, then the transmission structure can be simple, but the system cannot adapt to changes in receiving antenna configurations
Solution Approach 1:
The patent implements preliminary pre-coding at the BS before transmission to mitigate inter-user interference. By performing pre-coding calculation using available CSI (whether open-loop or closed-loop), the BS pre-processes the signal to reduce interference at the receiver, thereby maintaining a simple transmission structure while enabling adaptability to different antenna configurations through flexible pre-coding strategies
Data Source
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AI summary
A method, a system, a Base Station (BS) and a mobile terminal device for collaborative communication are disclosed, so as to multiplex open-loop and closed-loop users and improve a utilization rate of system frequency spectrum. The method includes: receiving Channel State Information (CSI) sent by a user, in which the CSI is CSI of a Line of Sight (LOS) signal of the user obtained by eliminating CSI of a multi-path signal (11); obtaining CSI of a closed-loop user having a channel that is orthogonal to a channel of the user (12); performing pre-coding calculation by using the CSI of the LOS signal of the user and the CSI of the closed-loop user (13); and sending communication data to the user by using a result of the pre-coding calculation (14).