MIMO Transmit Diversity Encoding via Segmented Alamouti Grouping
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Solution Overview
Problem
Existing wireless communication systems with multiple transmit antennas struggle to achieve maximum diversity and efficient decoding, especially when using more than two transmit antennas, as prior methods either fail to capture full diversity or require computationally expensive processes.
Innovation Solution
A signal encoding scheme that uses a rate-1 complex symbol per channel use, employing a rotating and interleaving process to transmit symbols over multiple antennas, allowing for symbol-by-symbol decoding and achieving maximum diversity with reduced decoding complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Alamouti code is used with more than two transmit antennas, then the system can support multiple antennas, but it fails to achieve maximum transmit diversity
Solution Approach 1:
The patent segments the transmission into multiple time slots and assigns different antenna combinations to each time slot. For example, in a 4-antenna system, time slot 1 uses antennas 1 and 2 with Alamouti coding, time slot 2 uses antennas 3 and 4, and subsequent slots reuse these combinations. This segmentation allows the system to achieve maximum diversity (N/2 groups of 2 antennas) while maintaining the simplicity of Alamouti coding within each group.
Solution Approach 2:
The patent employs periodic reuse of antenna combinations and Alamouti code structures across multiple time slots. The same two-antenna Alamouti configuration is periodically repeated with different antenna pairs, creating a cyclic pattern that maintains decoding simplicity while achieving full diversity over the complete transmission cycle.
2Reliability
If complex encoding schemes are used to achieve maximum diversity with more than two antennas, then diversity performance improves, but decoding complexity increases significantly
Solution Approach 1:
By segmenting the multi-antenna transmission into multiple two-antenna Alamouti groups across different time slots, the patent enables independent decoding of each time slot using simple Alamouti decoders. The receiver processes each time slot separately without needing complex joint decoding, thus achieving maximum diversity while maintaining low decoding complexity.
Solution Approach 2:
The patent maintains continuous transmission across all antennas by seamlessly transitioning between different antenna pairs in consecutive time slots. This continuous operation ensures that diversity is captured throughout the entire transmission period while the receiver continuously applies simple Alamouti decoding to each time slot without computational interruptions.
Data Source
AI summary
The invention relates generally to the field of signal encoding in a multiple input multiple output system in a wireless communication network. This invention specifically relates to a method of encoding and transmitting symbols in a rate-1 complex symbol per second per Hertz transmission system while achieving maximum diversity. The invention discloses a method of interleaving the complex symbols such that each interleaved symbol comprises information of at least two complex symbols where the complex symbols obtain values from a rotated constellation.