Cooperative Multipoint Channel Feedback With Variable Precoding Magnitudes
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Solution Overview
Problem
Conventional Joint Processing (JP) systems in Cooperative Multipoint transmission systems are limited by the constraint that all cooperating cells transmit at the same power level, which restricts system performance.
Innovation Solution
The system calculates and reports channel feedback that allows cooperating cells to use precoding vectors of different magnitudes, enabling them to transmit at varying power levels, with explicit or implicit Magnitude Information (MI) indicating recommended ratios between precoding vector magnitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If all cooperating cells transmit at the same power level in Joint Processing systems, then system simplicity is maintained, but system performance and downlink throughput are restricted
Solution Approach 1:
The patent changes the power level parameter from a fixed equal value to variable values across different cooperating cells. By allowing each cell to transmit at different power levels based on channel conditions and interference considerations, the system achieves improved downlink throughput while maintaining manageable complexity through standardized feedback mechanisms.
Solution Approach 2:
The patent introduces dynamic power level adjustment where cooperating cells can adapt their transmission power based on real-time channel feedback and interference conditions. This dynamic approach allows the system to optimize performance continuously rather than operating with static equal power levels, thereby resolving the contradiction between performance and complexity.
2Productivity
If channel feedback is calculated without magnitude information, then feedback overhead is reduced, but the ability to optimize precoding vector magnitudes is lost
Solution Approach 1:
The patent applies partial action by selectively including magnitude information in channel feedback only when it is needed for optimization. Rather than always transmitting full magnitude details, the system includes magnitude information selectively based on whether it will improve precoding optimization, thereby balancing information overhead with system efficiency gains.
Solution Approach 2:
The patent implements an enhanced feedback mechanism where magnitude information is incorporated into channel feedback from user equipment to the network. This feedback loop enables the network to adjust precoding vector magnitudes optimally, improving system efficiency while managing information overhead through structured feedback formats.
Data Source
Figure 1~2
AI summary
A method includes receiving in a mobile communication terminal (24) downlink signals from at least first and second cells (28) that coordinate transmission of the downlink signals with one another. Channel feedback is calculated in the terminal based on the received downlink signals. The channel feedback is configured to cause the first cell to precode subsequent downlink signals in response to the channel feedback with a first precoding vector, and to cause the second cell to precode the subsequent downlink signals in response to the channel feedback with a second precoding vector that differs in magnitude from the first precoding vector. The channel feedback is transmitted from the terminal.