# Low-Complexity Progressive MIMO-OFDM Receiver for Underwater Acoustic Communication

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## Abstract

**:**

## 1. Introduction

## 2. UWA MIMO-OFDM System Model

## 3. ICI Unaware Cost Function Based Soft Feedback Iterative Receiver

#### 3.1. OMP Channel Estimation

#### 3.2. Cost Function Controlled Soft Information Feedback

## 4. ICI Aware Progressive MIMO-OFDM Iterative Receiver

#### ICI Equalization of MIMO System

## 5. Results

#### 5.1. ICI Unaware Iterative Receiver

#### 5.1.1. Simulation Results

#### 5.1.2. Experimental Results

#### 5.2. ICI Aware Progressive Iterative Receiver

#### 5.2.1. Simulation Results

#### 5.2.2. Experimental Results

^{−5}, which confirms that the Doppler shift is really small. This may be due to the slow speed of the movement of the array by hand, as the transmitting array is relatively heavy and might not be disturbed properly, therefore, causing a smaller Doppler scaling factor. In this case, it is recommended to use the ICI-unaware iterative receiving algorithm, because of its closer performance to the ICI-aware progressive receiving algorithm with fewer processing and calculations.

## 6. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 2.**ICI unaware Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) Iterative Receiver block diagram.

**Figure 4.**Bit error rate (BER) simulation performance comparison of the proposed iterative receiver.

**Figure 6.**BER performance of non-progressive iterative MIMO receiver with different values of D and σv.

**Figure 7.**BER performance of progressive MIMO-OFDM iterative receivers with different values of D and σv.

**Figure 10.**Doppler scaling factor estimation values for different hydrophones for eight OFDM symbols in one frame.

Serial # | Parameter | Value |
---|---|---|

01 | Sampling frequency | 48 kHz |

02 | Communication bandwidth | 6 kHz–12 kHz |

03 | Total number of subcarriers | 1024 |

04 | Number of data carriers per transmitter | 726 |

05 | Number of pilots at each transmitter | 250 |

06 | Number of Null carriers per transmitter | 48 |

07 | OFDM symbol period | 170.67 ms |

08 | Cyclic prefix length | 40 ms |

09 | Spectrum utilization | 1.15 b/s/Hz |

10 | Communication rate | 6.89 kb/s |

**Table 2.**BER comparison of iterative MIMO-OFDM receiver for different number of combined hydrophones in pool experiment.

Value of Dmax | 0 | 1 | 2 | ICI-Unaware 3 Iterations | |
---|---|---|---|---|---|

Combined Hydrophone Number | |||||

02 | 0.2333 | 0.1911 | 0.1911 | 0.1911 | |

03 | 0.1757 | 0.0587 | 0.0208 | 0.0156 | |

04 | 0.1276 | 0.0018 | 0.0006 | 0.0006 | |

05 | 0.0796 | 0.0006 | 0.0006 | 0.0006 |

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**MDPI and ACS Style**

Qiao, G.; Babar, Z.; Zhou, F.; Ma, L.; Li, X.
Low-Complexity Progressive MIMO-OFDM Receiver for Underwater Acoustic Communication. *Symmetry* **2019**, *11*, 362.
https://doi.org/10.3390/sym11030362

**AMA Style**

Qiao G, Babar Z, Zhou F, Ma L, Li X.
Low-Complexity Progressive MIMO-OFDM Receiver for Underwater Acoustic Communication. *Symmetry*. 2019; 11(3):362.
https://doi.org/10.3390/sym11030362

**Chicago/Turabian Style**

Qiao, Gang, Zeeshan Babar, Feng Zhou, Lu Ma, and Xue Li.
2019. "Low-Complexity Progressive MIMO-OFDM Receiver for Underwater Acoustic Communication" *Symmetry* 11, no. 3: 362.
https://doi.org/10.3390/sym11030362