In real-world wireless communication systems, signals from multiple transmitters arrive at the receiver with different delays due to differences in propagation paths, leading to constructive and destructive interference. This causes fluctuations in received signal power, deterioration of instantaneous SNR, and degradation of transmit diversity performance below that of a single-antenna system.
A new study in Digital Communications and Networks presents an Alamouti-OFDM system designed to mitigate destructive interference in multi-transmitter wireless communications, where propagation delays result in signal cancellation and SNR fluctuations.
“Through comprehensive millimeter-wave experiments, we demonstrated that this integrated approach not only achieves the full spatial diversity gain promised by Alamouti coding in a 2-transmitter-1-receiver (2Tx-1Rx) configuration, but also effectively neutralises phase-induced destructive interference by leveraging the inherent subcarrier characteristics of OFDM, namely precise channel estimation, high subcarrier correlation, and minimal subcarrier-to-subcarrier phase variation,” says lead and co-corresponding author Jiali Chen.
Notably, the system achieves significant performance gains. “Under strictly aligned dual-transmit antenna conditions, a 10-Gbaud Quadrature Phase Shift Keying (QPSK) signal attains a BER of 1.6×10 −3 while exhibiting a 2.5 dB SNR improvement over Single-Input Single-Output (SISO) OFDM,” shares Chen.
Meanwhile, when under spatial misalignment conditions, the SNR gain compared to traditional schemes reaches 3.45 dB, significantly mitigating delay-induced fading. In a scenario with a 20-cm path difference between dual transmit antennas, the BER for a 10-Gbaud QPSK signal is reduced by an order of magnitude.
“Our findings show that the Alamouti-OFDM system is an effective solution for achieving reliable, high-rate communication in real-world scenarios plagued by asynchronous multi-transmitter delays and spatial mismatch,” adds Chen.
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Contact the author:
Jiali Chen
The State Key Laboratory of ASIC and System, Key Laboratory for Information Science of Electromagnetic Waves (MoE), and the School of Information Science and Technology, Fudan University, Shanghai, 200433, China
jialichen25@m.fudan.edu.cn
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Digital Communications and Networks
Computational simulation/modeling
Not applicable
Overcoming constructive/destructive interference in diversity transmission via Alamouti coding
The authors declare that they have no financial and personal relationships with other people or organizations that can inappropriately influence our work, and there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled “Overcoming constructive/destructive interference in diversity transmission via Alamouti coding”.