Retransmission Precoding Matrix Determination in LTE-A
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Solution Overview
Problem
In LTE-A systems, retransmissions fail due to the absence of uplink grant signaling, as the UE cannot determine the correct precoding matrix for retransmissions, especially when the rank of the retransmission differs from the initial transmission.
Innovation Solution
A method where the UE determines a precoding matrix for retransmissions based on a preset phase or index information, ensuring a fixed phase relationship to ensure successful retransmissions without uplink grant signaling, by using a specific phase or index number to identify the correct precoding matrix for each symbol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple antennas are used for simultaneous transmission in LTE-A, then the data transmission rate is improved, but the retransmission reliability deteriorates because the UE cannot determine the correct precoding matrix without uplink grant signaling
Solution Approach 1:
The patent applies preliminary action by pre-configuring the UE with multiple precoding matrices and their corresponding phase relationships before retransmission is needed. The network side provides precoding matrix determining information in advance, which the UE stores and uses for determining the correct precoding matrix during retransmission without requiring real-time uplink grant signaling.
2Measurement precision
If uplink grant signaling is used to indicate precoding matrix for retransmission, then the retransmission accuracy is improved, but the signaling overhead increases
Solution Approach 1:
The patent applies copying by having the UE store copies of multiple precoding matrices and their phase relationships in advance. Instead of transmitting the actual precoding matrix during retransmission, the network side sends compact determining information (such as index values or phase indicators) that the UE uses to retrieve the appropriate precoding matrix from its stored copies, significantly reducing signaling overhead.
3Adaptability or versatility
If the rank of retransmission differs from initial transmission, then the transmission adaptability is improved, but the precoding matrix determination becomes impossible without uplink grant signaling
Solution Approach 1:
The patent applies dynamics by making the precoding matrix determination process adaptive to different transmission ranks. The UE is configured with multiple precoding matrices corresponding to different ranks, and the determining information dynamically indicates which matrix to use based on the current transmission conditions. This allows the system to adapt between rank 1 and rank 2 transmissions while maintaining a systematic determination method.
Data Source
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AI summary
The present invention relates to the field of communications technologies, and discloses a retransmission method and apparatus, and a communication system. The method includes: after sending two channel-coded codewords in initial transmission, receiving a retransmission indication, where the retransmission indication includes an identifier of one channel-coded codeword to be retransmitted; according to a preset phase of each symbol, determining a precoding matrix of each symbol of the one channel-coded codeword to be retransmitted, where a phase relationship of each symbol is fixed; and after coding, by using the precoding matrix, each symbol of the one channel-coded codeword to be retransmitted, transmitting the coded symbol through an antenna. Through the present invention, a guarantee can be provided for retransmission success of a UE.