Antenna Pairing for Orthogonal Spatial Block Code Transmission
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Solution Overview
Problem
Existing space-time block codes (STBCs) for multiple transmitter antennas face challenges in maintaining orthogonality, leading to code rate loss and power imbalance, which affects signal quality and throughput in communication systems like LTE's PHICH channels.
Innovation Solution
A communication system employing spatial block codes transmitted consecutively over pairs of antennas, using a spreading factor to maintain orthogonality and balance power across antennas, allowing for efficient decoding with the Alamouti decoder while mitigating power imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If orthogonal STBC codes are used for multiple transmitter antennas, then signal quality and diversity order are improved, but code rate is reduced (code rate loss)
Solution Approach 1:
The patent segments the transmission system into pairs of antennas, with each pair transmitting a separate orthogonal STBC code. This allows the system to maintain orthogonality and signal quality within each pair while transmitting multiple pairs simultaneously, effectively resolving the code rate loss issue by distributing the transmission across multiple independent pairs.
Solution Approach 2:
The patent introduces a pairing dimension, organizing antennas into pairs rather than using all antennas simultaneously for a single code. This dimensional reorganization allows the system to achieve full diversity order through multiple pairs while maintaining code rate 1, as each pair independently transmits an orthogonal code without rate loss.
2Productivity
If quasi-orthogonal STBC codes are used to maintain code rate 1, then throughput is improved, but signal quality deteriorates due to loss of orthogonality
Solution Approach 1:
By segmenting the antenna system into pairs and assigning orthogonal codes to each pair, the patent ensures that each pair maintains full orthogonality and signal quality. The system achieves high throughput by utilizing multiple pairs simultaneously, avoiding the need to sacrifice orthogonality for rate 1 codes.
Solution Approach 2:
The patent changes the code rate parameter from less than 1 (for orthogonal codes with multiple antennas) to 1 (for orthogonal codes with paired antennas). This parameter change allows the system to maintain both orthogonality and throughput by distributing the transmission across multiple pairs rather than requiring all antennas to transmit a single rate-less-than-1 code.
3Reliability
If STBC codes are used for spatial diversity, then diversity order is improved, but power imbalance across transmit antennas occurs
Solution Approach 1:
The patent segments the transmission into multiple pairs, where each pair transmits an orthogonal STBC code. This segmentation allows for flexible power distribution across pairs, enabling the system to achieve full diversity order while maintaining power balance by adjusting the power allocation to each pair independently.
Data Source
AI summary
In accordance with embodiments, a communication system includes a first device and a second device in communication with the first device. The second device has at least a first pair and a second pair of antennas. The second device spreads a communication bit by a predetermined spreading factor and forms a first set of spatial block codes in frequency domain based on the spread communication bit. The first set of spatial block codes being consecutively transmitted on one of the first and second pairs of antennas.