Treffer: Asymmetric Modulation Physical-Layer Network Coding Based on Power Allocation and Multiple Receive Antennas in an OFDM-UWOC Three-User Relay Network.

In relay-assisted underwater wireless optical communication (UWOC) systems, the traditional time-division-multiplexed relay forwarding strategy faces high latency and low throughput with the increase of relay users. To address these issues, this paper proposes a multiple receiving antenna power allocation-based bit splicing physical layer network coding (MRA-PABS-PNC) method in a three-user asymmetric modulated relay-assisted UWOC scenario. MRA-PABS-PNC reduces the number of multiple access time slots by using multi-antenna reception techniques. At the same time, it employs a bit-splicing method to concatenate the data that would normally be transmitted over two-time slots into a longer data stream transmitted in a single time slot, thus reducing the number of broadcast time slots and ultimately improving throughput. Moreover, this paper models and determines the optimal position and angle of the relay node photodetector. Once the relay node is positioned at the optimal location and angle, the system can allocate power to each user node based on the channel state information to overcome the effect of asymmetric channels on PNC coding, thereby further improving system performance. Simulation results show that the method improves the throughput by 100% compared with the existing four-time slot PNC (FT-PNC) method. [ABSTRACT FROM AUTHOR]

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