MIMO MC-CDMA System Space-Time Block Encoding
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Solution Overview
Problem
Existing MIMO communication systems face challenges in simultaneously optimizing spectrum efficiency and diversity, especially in wide-band systems with Intersymbol Interference and non-perpendicular substreams, where conventional technologies fail to provide better diversity or spectrum efficiency.
Innovation Solution
A MIMO MC-CDMA communication system employing space-time block encoding and space-path spreading codes, which includes a transmitter with de-multiplexers, space-time block encoders, space-path spreaders, and multiple transmit antennas, and a receiver with matched filters, space-time linear combiners, and BLAST detectors to achieve improved spectrum efficiency and chain quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-code transmission technology is used to improve diversity gain, then diversity gain is improved, but spectrum efficiency deteriorates
Solution Approach 1:
The patent combines space-time block coding (STBC) with space-path spreading codes to create a hybrid MIMO MC-CDMA system. The STBC component provides diversity gain through space-time encoding, while the MC-CDMA component with space-path spreading codes maintains spectrum efficiency by utilizing code division multiplexing in the frequency domain. This merging of two different technologies allows simultaneous optimization of both diversity gain and spectrum efficiency.
Solution Approach 2:
The system employs a composite transmission approach combining spatial coding (STBC) and spectral spreading (MC-CDMA). The composite structure integrates the diversity-providing space-time block code with the spectrum-efficient multicarrier code division multiplexing, creating a hybrid system that leverages the strengths of both components to achieve improved diversity gain without sacrificing spectrum efficiency.
2Productivity
If conventional MIMO technologies are used in wide-band systems, then transmission is enabled, but transmission efficiency deteriorates due to Intersymbol Interference and non-perpendicular substreams
Solution Approach 1:
The patent segments the wide-band transmission into multiple orthogonal carrier frequencies (subcarriers). By dividing the broad frequency band into multiple narrowband MC-CDMA channels, each subcarrier experiences flat fading rather than frequency-selective fading, which eliminates Intersymbol Interference. The space-path spreading codes are applied independently to each subcarrier, maintaining transmission efficiency while avoiding ISI problems.
Solution Approach 2:
The space-path spreading codes act as an intermediary mechanism that orthogonalizes the transmission paths in the frequency domain. By introducing these spreading codes as a mediator between the transmitted signals and the channel, the system achieves perpendicular (orthogonal) substreams that eliminate mutual interference, thereby improving transmission efficiency in wide-band environments.
Data Source
AI summary
The present invention discloses a MIMO system and method, which is suitable for MC-CDMA communication system with multiple paths to obtain the spectrum efficiency and gain simultaneously. The transceiver performs steps of simultaneously transferring transmitting data to a plurality of parallel data streams, and space time block encoding each data, followed by spreading the encoded data streams with a pre-designed space-path spreading code, and transmitting data with the transmit antennas through multiple paths. Finally, at each receiver, despreading received data by the matched filters, and separating mutually interfering signals with a linear combiner and a BLAST detector to obtain the diversity gain.