Research on Power Allocation in Multiple-Beam Space Division Access Based on NOMA for Underwater Optical...

Area of Science:

• Underwater optical communication (UWOC)
• Optical networking
• Wireless communication systems

Background:

• Existing multiple-beam access systems face challenges in meeting diverse user transmission requirements.
• Ensuring Quality of Service (QoS) and fairness, particularly for edge users, remains a critical issue in shared optical communication channels.

Purpose of the Study:

• To propose a novel multiple-beam space division multiple access (MB-SDMA) system for UWOC.
• To develop a power allocation algorithm that guarantees QoS for both single-beam and multiple-beam users, prioritizing edge users and overall fairness.
• To establish an optimization model for power distribution considering LED emission power constraints.

Main Methods:

• Utilizing directional radiation from hemispherical LED arrays to create distinct communication beams.
• Classifying users into single-beam and multiple-beam access categories.
• Developing a power allocation algorithm based on an optimization model and solving it using Karush-Kuhn-Tucker (KKT) conditions and the bisection method.

Main Results:

• The proposed user classification and power allocation method effectively ensures fairness for all users while maintaining QoS for edge users.
• Simulations demonstrate significant throughput improvements compared to traditional orthogonal multiple access (OMA) systems, especially within non-orthogonal multiple access (NOMA) frameworks.
• The number of users was found to influence the improvement of the minimum data rate.

Conclusions:

• The novel MB-SDMA system and power allocation strategy successfully address QoS and fairness challenges in UWOC.
• The approach offers a viable solution for enhancing spectral efficiency and user experience in underwater optical networks.
• The findings highlight the advantages of NOMA over OMA in terms of throughput for UWOC systems.