Precoding Matrix Adaptation for Wireless Error Correction
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Solution Overview
Problem
Current multiple antenna systems face limitations in error correction, particularly in frequency selective channels with rapid changes, inefficiency in retransmitting all codewords when errors occur in some, and lack of flexibility in initial transmission schemes, which hampers data transmission speed and reliability.
Innovation Solution
A phase shift based precoding method that dynamically adjusts precoding matrices based on spatial multiplexing rates and offset information, allowing for adaptive ARQ schemes that reconstruct or change precoding matrices for retransmissions, enabling efficient error correction in both single and multi-codeword structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ARQ schemes retransmit all codewords when errors occur, then error correction is achieved, but data transmission efficiency deteriorates due to unnecessary retransmission of error-free codewords
Solution Approach 1:
The patent segments the transmission into multiple independent codewords, each with its own error detection status. Instead of treating all data as a single block requiring full retransmission, the system identifies and retransmits only the specific codewords that contain errors, thereby improving transmission efficiency while maintaining reliability.
Solution Approach 2:
The patent applies partial action by retransmitting only the necessary portion of data (error-containing codewords) rather than the entire transmission. This selective retransmission approach reduces unnecessary bandwidth consumption and improves overall system productivity while achieving the required error correction.
2Speed
If spatial multiplexing rate is maintained during retransmission, then data transmission speed is preserved, but error correction effectiveness deteriorates in frequency selective channels
Solution Approach 1:
The patent dynamically adjusts the spatial multiplexing rate based on channel conditions and error status. During initial transmission, a higher spatial multiplexing rate is used to maximize speed, but during retransmission of error-containing codewords, the system adapts by using more robust modulation and coding schemes that prioritize reliability over speed, thereby achieving both goals at different stages.
Solution Approach 2:
The patent changes key transmission parameters including spatial multiplexing rate, modulation order, and coding rate between initial transmission and retransmission phases. These parameter changes allow the system to optimize for speed during initial transmission and for reliability during retransmission, resolving the contradiction between speed and error correction effectiveness.
3Device complexity
If fixed precoding matrices are used for all sub-carriers, then device complexity is reduced, but adaptability to frequency selective channels deteriorates
Solution Approach 1:
The patent segments the frequency spectrum into multiple sub-carrier groups, each potentially using different precoding matrices. This segmentation allows the system to adapt to frequency-selective fading by applying appropriate precoding to different sub-carrier ranges, improving channel adaptability while maintaining manageable complexity through structured matrix selection.
Solution Approach 2:
The patent changes precoding matrix parameters across different sub-carrier groups based on channel conditions. By allowing precoding matrices to vary with frequency and channel state, the system achieves better adaptability to frequency selective channels while maintaining reasonable complexity through standardized matrix libraries and selection algorithms.
4Productivity
If all transmitting antennas are used simultaneously, then data transmission capacity is maximized, but error correction capability deteriorates in certain channel conditions
Solution Approach 1:
The patent dynamically selects which transmitting antennas to use based on channel conditions and error status. During initial successful transmissions, all antennas may be utilized to maximize capacity. However, when errors are detected, the system adaptively adjusts antenna selection and spatial multiplexing configuration to improve reliability, thereby resolving the contradiction between capacity and error correction capability.
Solution Approach 2:
The patent applies different transmission strategies to different spatial streams and antennas based on local channel conditions. Instead of treating all antennas uniformly, the system identifies which antenna combinations provide the best error correction performance for specific codewords and channel conditions, thereby achieving both high capacity and robust error correction.
Data Source
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AI summary
A method for a spatial multiplexing, SM, transmission by using multiple antennas in wireless access system, is proposed, which comprises: performing a first transmission based on a first precoding matrix, wherein the first precoding matrix is a two by two matrix for the SM transmission; receiving feedback information related to the first transmission; and preforming a second transmission based on a second precoding matrix which is configured only with one of columns from the first precoding matrix, wherein a spatial multiplexing rate of the first transmission is two and a spatial multiplexing rate of the second transmission is one, and wherein the second precoding matrix is configured based on the feedback information.