MIMO Transmission Device Orthogonal ACK/NACK Mapping
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Solution Overview
Problem
In MIMO transmission for ACK/NACK signals in RANK 2, the existing methods either map the signal on one stream to prevent interference or on both streams to increase power, leading to potential beam-forming issues that degrade reception quality.
Innovation Solution
A MIMO transmission apparatus and method that maps the first and second elements of a response signal vector on separate streams within the same subframe, making them orthogonal and applying precoding using a unitary matrix, to improve reception quality by preventing beam-forming degradation and achieving spatial diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ACK/NACK signal is mapped on one stream only, then inter-stream interference is prevented, but transmission power is reduced
Solution Approach 1:
The invention divides the ACK/NACK signal transmission into two separate streams, where the first element of the response signal vector is mapped on the first stream and the second element is mapped on the second stream. This segmentation allows the signal to utilize both transmission streams simultaneously, thereby increasing transmission power while maintaining orthogonality to prevent inter-stream interference.
Solution Approach 2:
The invention transitions from mapping the ACK/NACK signal on a single stream (one-dimensional) to mapping it across two streams (two-dimensional). By utilizing multiple spatial dimensions (streams), the system achieves both higher transmission power and interference prevention through orthogonal mapping.
2Power
If the ACK/NACK signal is mapped on both streams, then transmission power is increased, but beam-forming degradation occurs
Solution Approach 1:
The invention applies different mapping strategies to different elements of the response signal vector. The first element is mapped on the first stream and the second element on the second stream, creating localized quality differentiation. This approach ensures that each stream contributes to the transmission power while maintaining orthogonality, thereby preventing beam-forming degradation and ensuring reliable reception.
3Device complexity
If the first and second elements of the response signal vector are mapped on the same stream, then device complexity is reduced, but spatial diversity is lost
Solution Approach 1:
The invention segments the mapping process by assigning the first element of the response signal vector to the first stream and the second element to the second stream. This segmentation increases spatial diversity by utilizing multiple transmission paths simultaneously, while the structured mapping approach keeps device complexity manageable through clear assignment rules.
Data Source
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AI summary
Provided are a MIMO transmission device and a MIMO transmission method which can improve reception quality of a response signal. A terminal (100) as the MIMO transmission device maps a first and a second element of the ACK/NACK signal vector formed from ACK/NACK signals onto a first and a second stream, respectively, and transmits the elements contained in a 2SC-FDMA symbol in a single slot. In the terminal (100), a response signal vector formation unit (140) forms [aSack, O] as the ACK/NACK signal vector in a first SC-FDMA symbol and [O, aSack] as an ACK/NACK signal vector in a second SC-FDMA symbol. A precoding unit (165) uses a unitary matrix to precode the ACK/NACK signal vector formed in the response signal vector formation unit (140).