Downlink MIMO Transmission Control for Wireless Base Stations
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Solution Overview
Problem
Current wireless communication techniques lack an efficient method to combine MIMO transmission control techniques with the state of physical channels, leading to suboptimal communication efficiency.
Innovation Solution
The use of open loop-type MIMO diversity for common control channels and closed loop-type MIMO multiplexing/diversity for shared data channels, with user-specific allocation of sub-carriers and pre-encoding vectors based on channel state, allowing for adaptive control of the number of streams and encoding vectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MIMO transmission techniques are applied to increase transmission speed and capacity, then data throughput increases, but control complexity and resource allocation difficulty increase
Solution Approach 1:
The patent segments the downlink transmission into different physical channels (common control channels, shared data channels, etc.) and applies different MIMO transmission schemes to each segment. Common control channels use open-loop MIMO diversity while shared data channels use closed-loop MIMO multiplexing, allowing optimized control for each channel type without increasing overall system complexity
Solution Approach 2:
The patent implements dynamic adaptation by categorizing users into localized-transmission type and distributed-transmission type based on channel conditions, and dynamically selecting appropriate MIMO schemes (MIMO multiplexing, MIMO diversity, or transmit diversity) and pre-encoding vectors accordingly. This dynamic selection optimizes throughput while maintaining manageable control complexity
2Productivity
If MIMO multiplexing with multiple streams is used to increase transmission rate, then frequency utilization improves, but reliability and error detection difficulty worsen
Solution Approach 1:
The patent incorporates feedback mechanisms where the mobile station measures channel quality and feeds back pre-encoding vector information to the base station. This feedback enables the base station to select appropriate pre-encoding vectors and MIMO schemes that maintain reliability while achieving high transmission rates through spatial multiplexing
Solution Approach 2:
The patent changes transmission parameters dynamically by selecting different pre-encoding vectors from codebooks based on channel conditions. The system adjusts the number of streams, pre-encoding vector selection, and MIMO scheme type according to measured channel quality, maintaining reliability while optimizing transmission rate
3Device complexity
If open loop MIMO diversity is applied to all channels to simplify control, then device complexity reduces, but communication efficiency for data channels deteriorates
Solution Approach 1:
The patent applies different MIMO transmission qualities to different parts of the system: open-loop MIMO diversity is applied to common control channels where simplicity is adequate, while closed-loop MIMO multiplexing with adaptive pre-encoding is applied to shared data channels where high efficiency is critical. This local differentiation optimizes overall communication efficiency without excessive complexity
Data Source
Figure 1A~1B
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AI summary
A method of controlling downlink transmission from a base station having multiple antennas to a mobile station having multiple antennas includes the steps of applying open loop-type MIMO diversity to one or more common control channels, an MBMS channel, and an L1/L2 control channel; and applying closed loop-type MIMO multiplexing and/or MIMO diversity to a shared data channel.