Back to Search Start Over

Research on Adaptive Transmit Diversity Strategy for Reducing Interference in Underwater Optical Multi-Beam Non-Orthogonal Multiple Access Systems

Authors :
Yanlong Li
Yutong Jiang
Xiao Chen
Pengcheng Jiang
Shuaixing Li
Yu Hu
Source :
Photonics, Vol 10, Iss 10, p 1152 (2023)
Publication Year :
2023
Publisher :
MDPI AG, 2023.

Abstract

With the rapid development of the underwater Internet of Things (IoT), the number of underwater communication nodes is rapidly increasing. The access capacity of a traditional multi-antenna communication system is limited by the number of transmitting antennas, and multi-beam communication systems using non-orthogonal multiple access (NOMA) technology can enhance the access capacity of the system. However, this can lead to serious inter-beam and intra-beam interference. To address the severe issues of inter-beam and intra-beam interference in underwater multi-beam NOMA systems, we propose an adaptive transmit diversity strategy. We design an algorithm for adaptive selection and merging beams based on the degree of interference between beams in space, which merges LED beams with high interference. Diversity technology is used to reduce interference between beams, and spatial multiplexing is still performed between LED groups with low interference. Within the same beam, we use an OFDM-NOMA scheme to match and group the users. Signals from different user groups are sent through different subcarriers to improve resource utilization. This enhances access capacity while reducing NOMA inter-user interference. Simulation results show that the bit error rate (BER) of users with the adaptive transmit diversity strategy satisfies the forward error correction (FEC) limits in the presence of high inter-beam interference and has a better reachable rate and BER performance compared to the multi-beam access system without interference management. We also analyze the system BER performance of the proposed strategy in the multi-user case, and the BER of all 32 access nodes are lower than the FEC threshold at a communication distance of 5 m. This demonstrates that the strategy can effectively reduce the interference of the multi-beam NOMA system.

Details

Language :
English
ISSN :
10101152 and 23046732
Volume :
10
Issue :
10
Database :
Directory of Open Access Journals
Journal :
Photonics
Publication Type :
Academic Journal
Accession number :
edsdoj.5ce807e941278693f663500e8035
Document Type :
article
Full Text :
https://doi.org/10.3390/photonics10101152