Research on Co-Channel Interference Cancellation for Underwater Acoustic MIMO Communications

Abstract

Multiple-input–multiple-output (MIMO) communication systems utilize multiple transmitters to send different pieces of information in parallel. This offers a promising way to communicate at a high data rate over bandwidth-limited underwater acoustic channels. However, underwater acoustic MIMO communication not only suffers from serious inter-symbol interference, but also critical co-channel interference (CoI), both of which degrade the communication performance. In this paper, we propose a new framework for underwater acoustic MIMO communications. The proposed framework consists of a CoI-cancellation-based channel estimation method and channel-estimation-based decision feedback equalizer (CE-DFE) with CoI cancellation functionalities for underwater acoustic MIMO communication. We introduce a new channel estimation model that projects the received signal to a specific subspace where the interference is free; therefore, the CoI is cancelled. We also introduce a CE-DFE with CoI cancellation by appending some filters from traditional CE-DFE. In addition, the traditional direct adaptive decision feedback equalization (DA-DFE) method and the proposed method are compared in terms of communication performance and computational complexity. Finally, the sea trial experiment demonstrates the effectiveness and merits of the proposed method. The proposed method achieves a more than 1 dB of output SNR over traditional DA-DFE, and is less sensitive to parameters. The proposed method provides a new approach to the design of robust underwater acoustic MODEM.

Iterative Signal Detection and Channel Estimation with Superimposed Training Sequences for Underwater Acoustic Information Transmission in Time-Varying Environments

“…However, it primarily addresses the block sparsity problem and is effective only at high SNRs and for channels with strong correlation. The scheme is more suitable for scenarios where MIMO diversity gain is insignificant, indicating the presence of strongly correlated cochannel interference [29]. Currently, minimal research has focused on time-varying channel models and their channel estimation and equalization.…”

SPACNet: A Simulation Platform of an Acoustic Cognitive Network

“…The technology of underwater acoustic networks (UAN) has drawn substantial attention due to its significant potential in extensive civil and military fields, e.g., marine environment monitoring [1], marine resource exploration [2], marine disaster warning [3], underwater information acquisition and transmission [4], autonomous underwater vehicleassisted navigation [5], communication between scuba divers [6], military applications [7], etc. Evolved from the concept of cognitive radio, the cognitive network (CN) technique has characteristics that optimize a network via environmental sensing, adaptive adjustment, intelligent decision-making, and reconfiguration.…”

“…However, while cognitive networks have achieved significant progress in academic research, the R&D of the standard network model, and practical commercial applications based on established wireless channel sensing and cognitive optimization strategies [1][2][3][4][5][6][7][8], the specific implementation of CNs in the underwater acoustic channel still encounter many difficulties due to the highly diverse channel patterns, underwater acoustic (UWA) communication modes, and network protocols.…”