Quasi-Orthogonal Space-Time Block Coding Matrix Design
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Solution Overview
Problem
In mobile communication systems, increasing the number of antennas beyond two leads to a reduction in encoding rate for orthogonal space-time block coding, resulting in reduced spectral efficiency and complex decoding algorithms due to loss of orthogonality in quasi-orthogonal space-time block coding methods.
Innovation Solution
A method is developed to generate a diagonal Grammian matrix by applying a rotation matrix to the initial Grammian matrix, allowing for a quasi-orthogonal space-time block coding system with an encoding rate of 1 and simple linear decoding, using a system with four transmitting antennas and one receiving antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If orthogonal space-time block coding is used with three or more transmitting antennas, then diversity gain is increased, but encoding rate decreases below 1
Solution Approach 1:
The patent changes the Gramian matrix from a non-diagonal form to a diagonal form through specific matrix design. This parameter change in the encoding matrix structure enables both high encoding rate (1/2) and full orthogonality to be achieved simultaneously with three or four transmit antennas, resolving the contradiction between diversity gain and encoding rate.
2Productivity
If quasi-orthogonal space-time block coding is used to maintain encoding rate of 1, then spectral efficiency is improved, but decoding complexity increases and orthogonality is not maintained
Solution Approach 1:
The patent designs the encoding matrix such that its Gramian matrix is diagonal, which is a specific parameter change in the matrix structure. This ensures that the encoding rate remains 1 while maintaining complete orthogonality, thereby simplifying decoding complexity and eliminating the need for complex non-linear decoding algorithms.
3Productivity
If quasi-orthogonal space-time block coding is used, then encoding rate is maintained at 1, but adjacent signal interference increases
Solution Approach 1:
The patent changes the Gramian matrix to a diagonal matrix through careful design of the encoding matrix parameters. This parameter change ensures that columns of the encoding matrix are mutually orthogonal, which eliminates adjacent signal interference while maintaining encoding rate of 1, as the orthogonality prevents signal leakage between different transmitted symbols.
Data Source
AI summary
The present invention relates to a quasi-orthogonal space-time block coding system and method. The system does not become particularly complicated since the encoding rate is given as 1 and it is possible to decode the encoded signal by using a simple linear algorithm, and system performance is increased since there is no interference component of an adjacent signal in the estimated signal.