MIMO Downlink Mode Switching via Channel Fading Rate
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Solution Overview
Problem
Current MIMO downlink scheduling algorithms fail to adequately account for user mobility and feedback delay, limiting the effectiveness of closed-loop systems and preventing the intermixing of open-loop and closed-loop coding modes in multi-user MIMO systems.
Innovation Solution
A method and apparatus for MIMO downlink transmission control that calculates the channel fading change rate and feedback delay to determine a closed-loop MIMO throughput gain, allowing for dynamic switching between closed-loop and open-loop modes based on this gain, thereby supporting intermixing of open-loop and closed-loop modes and improving multi-user joint transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closed-loop MIMO technology is used to achieve better link reliability and higher system throughput, then precoding performance is improved, but the system becomes vulnerable to feedback delay and user mobility
Solution Approach 1:
The patent implements dynamic mode switching between closed-loop and open-loop MIMO based on real-time assessment of feedback delay and channel fading change rate. The system transitions from a static closed-loop configuration to a dynamic system that adapts its operating mode according to current channel conditions, resolving the contradiction between relying on feedback for precoding and suffering from feedback delay.
Solution Approach 2:
The patent changes the operational parameter (transmission mode) based on the feedback delay parameter and channel fading change rate parameter. By monitoring these parameters and switching between closed-loop and open-loop modes accordingly, the system optimizes performance under varying feedback delay conditions while maintaining link reliability.
2Productivity
If closed-loop MIMO is used to achieve higher system throughput, then precoding improves link reliability, but mobility causes CSI quantization errors that degrade performance
Solution Approach 1:
The patent dynamically switches between closed-loop and open-loop modes based on the channel fading change rate, which reflects user mobility. When mobility is high, the system transitions to open-loop mode to avoid CSI quantization errors. When mobility is low, it uses closed-loop mode to maximize throughput, thus resolving the contradiction between throughput and measurement precision.
Solution Approach 2:
The patent uses feedback about channel conditions (fading change rate and feedback delay) to adjust the transmission mode. This feedback mechanism allows the system to recognize when CSI quantization errors become significant due to mobility and switch to open-loop mode accordingly, maintaining accurate channel knowledge when needed while avoiding errors when mobility is high.
3Adaptability or versatility
If existing MIMO scheduling algorithms are used, then user CSI is considered for scheduling, but they cannot reflect user mobility properly and do not support intermixing of open-loop and closed-loop modes
Solution Approach 1:
The patent creates a universal MIMO transmission system that can operate in both closed-loop and open-loop modes and switch between them based on channel conditions. This multi-functional approach allows the system to handle both low-mobility scenarios (closed-loop) and high-mobility scenarios (open-loop), as well as mix the two modes for different users, thereby achieving mode intermixing capability and proper mobility reflection.
Data Source
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AI summary
A Multi-Input Multi-Output (MIMO) downlink transmission control method that is related to communications technologies is disclosed in embodiments of the present invention. The method includes: obtaining a channel fading change rate and a feedback delay of a user; calculating out a closed-loop MIMO throughput gain according to the channel fading change rate and the feedback delay; and determining a downlink transmission mode according to the closed-loop MIMO throughput gain, wherein the downlink transmission mode includes a closed-loop mode or an open-loop mode. A MIMO downlink transmission control apparatus is also disclosed. In the embodiments of the present invention, a downlink transmission mode is selected according to the channel fading change rate (namely, mobility) and the feedback delay of the user, and therefore, different operation modes (an open-loop mode and a closed-loop mode) are supported simultaneously to facilitate multi-user joint transmission, and the downlink throughput is increased by using mobility difference between users.