A Multi-User Detection Scheme Based on Polar Code Construction in Downlink Underwater Acoustic OFDM Communication System

Abstract

In this paper, we propose a novel polar code construction scheme, suitable for the underwater acoustic (UWA) multiuser communication system using orthogonal frequency division multiplexing (OFDM). We use the polar codes because the code rate of a polar code can be arbitrarily designed. Moreover, the polar codes can also be used to create a nested code structure, divided into several subsets (codebook). We exploit this feature of the polar codes and place the information bits in the codebook to avoid superimposition of all the users. This helps to eliminate the influence of the power allocation coefficient and make full use of the power of the transducer at the transmitted node. Furthermore, the proposed scheme maximizes the utilization efficiency of the OFDM subcarrier resource for each user by avoiding null pilot tones that are usually required for channel equalization in the traditional schemes. The proposed scheme also does not depend on the channel state information (CSI) as prior information as each user can decode their own data independently by using their own codebook without successive interference cancellation (SIC). The simulation and tank experiment results demonstrate that the proposed scheme can significantly guarantee the reliability of all the users, and reduces the complexity of the receiver, thus making it most suitable for the downlink UWA multiuser communication systems. INDEX TERMS Underwater acoustic communication (UAC), orthogonal frequency division multiplexing (OFDM), multiuser detection, polar code construction.

A Comparative Study on Channel Coding Scheme for Underwater Acoustic Communication

“…PC offer very low complexity and explicit construction encoding and decoding. Furthermore, arbitrary design of the code rate of a PC is possible making it more flexible for applications to various scenarios, such as security coding on the physical layer [4]. PC can be defined as (N, K) with N and K denoting the encoded block and the information block lengths, respectively.…”

“…Communications across shallow seawater channels are characterized by high multipath, high noise level, strong Doppler and other complex random transmission features. These complicate underwater communication (UWC) in terms of reliability and a low data rate compared with wireless communication [4]. on the requirements.…”

Polar Coding Aided by Adaptive Channel Equalization for Underwater Acoustic Communication

“…Polar code is the first method that theoretically reaches the Shannon limitation, and has lower coding complexity than low-density parity-check (LDPC) and Turbo codes. Nevertheless, there are few works studying on polar codes for the UWA channels [2][3][4]. Monte Carlo [2,3] and Bhattacharyya boundary [3,4] approaches are often used to construct polar codes.…”

“…Nevertheless, there are few works studying on polar codes for the UWA channels [2][3][4]. Monte Carlo [2,3] and Bhattacharyya boundary [3,4] approaches are often used to construct polar codes. However, the former is based on statistical performances, while the latter requires the feedback of channel gains and noise variance.…”

Real Time End To End System for Underwater Communication

“…They reach 2.8 Kbps to 9 Kbps data rate with 10 -4 Bit Error Rate. OFDM Modulation is also combined with Polar Coding [11] where 10 -7 Bit Error Rate is reached at 7 dB SNR.…”