Multi-Antenna Spatial-Frequency Encoding for Diversity and Rate
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Solution Overview
Problem
Existing multi-antenna transmitting systems face challenges with encoding rate when the number of transmit antennas is greater than 2, puncturing effects from improper delay values, and inability to obtain diversity gain when using spatial multiplexing coding alone.
Innovation Solution
Implementing spatial-frequency encoding combined with phase shifting, where encoded data is mapped to the same sub-carrier on each antenna and phase shifts are added to the encoded data on different sub-carriers, followed by OFDM modulation and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spatial multiplexing coding is used to improve transmission rate, then spatial multiplexing gain is achieved, but diversity gain cannot be obtained
Solution Approach 1:
The patent merges spatial-frequency block code (SFBC) with cyclic shift diversity (CSD) to create a hybrid transmission scheme. SFBC provides diversity gain through orthogonal encoding across multiple antennas, while CSD provides spatial multiplexing capability through cyclic shifts. By combining these two techniques, the system simultaneously achieves both diversity gain and spatial multiplexing gain, resolving the contradiction between reliability and transmission rate.
2Reliability
If orthogonal spatial-frequency encoding is used with more than 2 transmit antennas, then diversity gain is achieved, but encoding rate drops below 1
Solution Approach 1:
The patent segments the transmit antennas into multiple groups and applies different cyclic shift values to each group. This segmentation allows the system to maintain orthogonal encoding within each group (preserving diversity gain) while using different cyclic shifts to increase the overall encoding rate. The segmentation strategy enables the system to scale to more than 2 antennas without sacrificing encoding efficiency.
3Reliability
If cyclic shift diversity is used to improve frequency diversity gain, then transmission reliability is enhanced, but puncturing effects occur with improper delay values
Solution Approach 1:
The patent carefully selects and optimizes the cyclic shift values as key parameters to avoid puncturing effects. By choosing appropriate delay values that are proper multiples of the basic cyclic shift unit, the system achieves frequency diversity gain without introducing harmful puncturing effects. This parameter optimization ensures that the channel estimates remain reliable while still obtaining diversity benefits.
Data Source
AI summary
The present disclosure relates to communication technologies and discloses a method and apparatus for multi-antenna transmitting based on spatial-frequency encoding. The method includes: performing spatial-frequency encoding on input data and outputting encoded data; mapping the encoded data to the same sub-carrier of each antenna in an antenna group; adding a phase shift to the encoded data on different sub-carriers of each antenna; OFDM-modulating the phase-shifted encoded data on each antenna; and transmitting the OFDM-modulated data by transmit antennas.