Space-Time Block Coding With Orthogonal Columns For Antenna Diversity
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Solution Overview
Problem
Existing space-time block coding techniques fail to achieve maximum diversity gain and high transmission rates when using 3 or more transmit antennas, especially when transmitting complex symbols, due to increased decoding complexity and reduced transmission efficiency.
Innovation Solution
A transmitter and receiver system that uses space-time block coding with symbol combinations including inversions and conjugates, and phase-rotated symbols to form orthogonal columns, allowing for maximum diversity gain and simple encoding/decoding structure, even with 3 or more transmit antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional space-time block coding is used with 3 or more transmit antennas, then the system can provide transmit diversity, but the decoding complexity increases exponentially and transmission rate decreases
Solution Approach 1:
The patent segments the complex symbol transmission into multiple real symbol streams that can be independently decoded. By transforming the complex-valued space-time block code into real-valued equivalent representations, the decoding process is divided into simpler real-number operations rather than complex-number operations, reducing computational complexity while maintaining diversity gain with 3 or more transmit antennas
Solution Approach 2:
The patent changes the parameter representation from complex symbols to real symbol equivalents. This parameter transformation allows the system to achieve the same diversity gain using real-valued mathematics, which has lower computational complexity than complex-valued mathematics, thereby resolving the contradiction between reliability and device complexity
2Reliability
If conventional space-time block coding is used with 3 or more transmit antennas, then transmit diversity is provided, but transmission rate is reduced due to orthogonality constraints
Solution Approach 1:
The patent transitions from complex symbol dimension to real symbol dimension, effectively adding a dimensional transformation that allows more efficient packing of information. By representing complex symbols in terms of real and imaginary components separately, the system achieves higher transmission rates while maintaining the orthogonality required for diversity gain with multiple transmit antennas
3Reliability
If complex symbols are transmitted through 3 or more antennas using conventional space-time block codes, then diversity gain is limited, but decoding complexity and data rate losses increase
Solution Approach 1:
Instead of directly transmitting complex symbols through multiple antennas with conventional space-time block codes, the patent inverts the approach by first transforming complex symbols into real symbol equivalents, then encoding these real symbols through the space-time block code structure. This inversion allows the system to achieve maximum diversity gain without the data rate losses and decoding complexity penalties associated with conventional complex-symbol-based approaches
Data Source
AI summary
A transmitter and a receiver are disclosed herein that support transmit antenna diversity using space-time block coding in a wireless communication system. The transmitter produces symbol combinations containing, as their elements, input symbols, the inversions and conjugates of the symbols, and symbols obtained by rotating the phases of the symbols once, forms a matrix having symbols in at least two columns orthogonal to each other with the symbol combinations, and transmits the matrix. The receiver detects symbols that minimize maximum likelihood (ML) decoding metrics over all possible symbols using channel gains from transmit antennas to a receive antenna. Also, the receiver selects candidate symbols among all possible symbols according to the characteristics of transmitted modulation symbols and detects symbols that minimize the ML decoding metrics.