# Efficient and Robust Image Communication Techniques for 5G Applications in Smart Cities

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## Abstract

**:**

## 1. Introduction

## 2. Related Work

#### Our Contribution

- DCT transform is being utilized to improve the BER performance in place of Fourier transform in the OFDM system for efficient transmission of the image.
- A hybrid combination of MIMO-OFDM system is presented as a valid alternative to the conventional OFDM system for image transmission.
- The numbers of antennas are varied at the receiver side to access the MIMO-OFDM system’s performance and incorporate diverse transforms for multimedia applications.

## 3. Model Description

#### 3.1. FFT-OFDM System Model

^{th}element of discrete-time complex OFDM symbol can be written as:

_{k}represents the input signal, and X

_{n}represents the OFDM symbols obtained after the Fourier transform. After the orthogonal mapping of the data, the addition of guard interval is being done, ensuring that the received data would be free from the ISI effects. At the receiver end, the entire process is reversed to extract the original information.

#### 3.2. DCT-OFDM System Model

_{k}represents the input signal, and X

_{n}represents the n

^{th}OFDM symbols obtained after DCT transform.

#### 3.3. Maximal Ratio Combining (MRC)

_{i}s in Figure 2 are all zero. Subsequently, the signals are co-phased, α

_{i}= α

_{i}${\mathrm{e}}^{-{\mathrm{j}\mathsf{\theta}}_{\mathrm{i}}}$, where ${\mathsf{\theta}}_{\mathrm{i}}$ is the phase of the incoming signal in the ith branch. The envelope of the combiner output is presented in Equation (3). It represents that the received signal is the submission of the input signal coming from different branches, i.e., ${\mathrm{r}}_{\mathrm{i}}$ multiplied by different weight parameters.

_{0}in each branch yields a total noise PSD. N

_{tot}at the combiner output of and is depicted in Equation (4).

_{tot}represents the total noise power at the receiver side. It is very evident from Equation (4) that the total noise power also depends upon the weight parameters. The weight parameters are decided to boost the signal that contains the information components and attenuate the signal, which contains noise components. Therefore, the output SNR of the combiner is presented in Equation (5). It depicts that the SNR is the ratio of the weighted received signal and weighted noise signal of all the branches. The weight parameters must be optimally defined to have maximum SNR.

## 4. Proposed System Model and Parameters

## 5. Result Analysis and Discussion

^{−4}, in AWGN channel scenario, BPSK modulated FFT-OFDM necessitates SNR of 19 dB, but it reduces up to 8 dB for FFT-OFDM with MRC (1 Tx and 2 and 3 Rx). A similar observation can be made for the DCT-OFDM with MRC (1 Tx and 2 and 3 Rx), which requires 5.3 dB of SNR in comparison to 16 dB of SNR it requires without MRC. For QPSK modulation in AWGN scenario, FFT-OFDM requires 23.5 dB of SNR, which is more than 12 dB required in the case of FFT-OFDM with MRC. On the other hand, the same modulation system requires 22 dB and 10.5 dB of SNR to achieve the desired BER for DCT-OFDM without MRC and DCT-OFDM with MRC. Consequently, it is summarized that DCT-OFDM improves 1–3 dB of SNR over FFT-OFDM in AWGN and Rayleigh fading channel scenarios. It is further concluded that on employing the MRC schemes, significant improvement in SNR ranging in between 10–12 dB for both FFT-OFDM and DCT-OFDM has been reported in work.

## 6. Conclusions and Future Scope

## Author Contributions

## Funding

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 4.**Received Image with FFT-OFDM over a AWGN channel, Modulated with QPSK and at SNR = 0, 5, 10, 15 dB from L => R with MRC (nTx = 1 and nRx = 1 and 2).

**Figure 5.**Received Image with DCT-OFDM over a AWGN channel, Modulated with QPSK and at SNR = 0, 5, 10, 15 dB from L => R with MRC (nTx = 1 and nRx = 1 and 2).

**Figure 6.**Received Image with FFT-OFDM over a Rayleigh channel, Modulated with QPSK and at SNR = 0, 5, 10, 15 dB from L => R with MRC (nTx = 1 and nRx = 1 and 2).

**Figure 7.**Received Image with DCT-OFDM over a Rayleigh channel, Modulated with QPSK and at SNR = 0, 5, 10, 15 dB from L => R with MRC (nTx = 1 and nRx = 1 and 2).

**Figure 8.**Received Image with FFT-OFDM over a Rayleigh channel, Modulated with QPSK at Eb/No = 0, 5, 10, 15 dB from left to right with MRC (nTx = 1 and nRx = 1 and 2).

**Figure 9.**Received Image with DCT-OFDM over a Rayleigh channel, Modulated with QPSK at Eb/No = 0, 5, 10, 15 dB from left to right with MRC (nTx = 1 and nRx = 1 and 2).

**Figure 10.**Received Image with FFT-OFDM over a Rayleigh channel, Modulated with QPSK at Eb/No = 0, 5, 10, 15 dB from left to right with MRC (nTx = 1 and nRx = 1 and 2).

**Figure 11.**Received Image with DCT-OFDM over a Rayleigh channel, Modulated with QPSK at Eb/No = 0, 5, 10, 15 dB from left to right with MRC (nTx = 1 and nRx = 1 and 2).

**Figure 12.**SNR vs. BER comparison of FFT-OFDM and DCT-OFDM for diverse Modulations over AWGN channel with MRC (nTx = 1 and nRx = 1, 2, 3), (

**a**) BPSK (

**b**) QPSK (

**c**) 8-PSK (

**d**) 16-PSK.

**Figure 13.**SNR vs. BER comparison of FFT-OFDM and DCT-OFDM for diverse Modulations over Rayleigh channel with MRC (nTx = 1 and nRx = 1, 2), (

**a**) BPSK (

**b**) QPSK (

**c**) 8-PSK (

**d**) 16-PSK.

Article | Research Outcome |
---|---|

BER Performance Analysis of Image Transmission Using OFDM Technique in Different Channel Conditions Using Various Modulation Techniques, Computational Intelligence in Data Mining. | This paper discussed the BER performance analysis of Image Transmission over conventional OFDM system using various modulation technique. The present manuscript presents the BER performance analysis of MIMO-OFDM system, which makes it more appropriate for the current application requirements of 5G systems. |

A two layer chaotic encryption scheme of secure image transmission for DCT precoded OFDM-VLC transmission. | In this paper, a two-layer image encryption scheme for a discrete cosine transform (DCT) pre-coded orthogonal frequency division multiplexing (OFDM) visible light communication (VLC) system is proposed. The present manuscript also utilized the concept of DCT pre-coded OFDM system, but it has been analyzed over radio channel and by employing multiple antennas at receiver side. Additionally, in addition to using BER performance as comparison metric, PSNR vs. SNR and SSIM are also used to present the reliability of the proposed methodology. |

Performance assessment of pre-coded OFDM using discrete cosine-based DOST transform. | In this research article an innovative precoding method has been proposed based on Discrete Cosine-based DOST (DCST) to lessen the High PAPR values and BER in OFDM systems. A similar concept of precoding is being utilized in the present manuscript with the use of DCT instead of DCST transform. Moreover, the analysis is carried out by utilizing the image transmission methodology instead of generic data sequences. |

Optimized OFDM transmission of encrypted image over fading channel. | This paper compares the quality of diffusion-based and permutation-based encrypted image transmission using orthogonal frequency division multiplexing (OFDM) over wireless fading channel. In the present manuscript, no encryption is being utilized. The comparison of the quality of transmitted and received image is carried out with the help of SSIM metric. |

**Table 2.**PSNR values for FFT-OFDM and DCT-OFDM for BPSK with MRC (nTx = 1 and nRx = 1, 2) over AWGN Channel.

SNR | FFT-OFDM | DCT-OFDM | ||
---|---|---|---|---|

1 Tx and 1 Rx | 1 Tx and 2 Rx | 1 Tx and 1 Rx | 1 Tx and 2 Rx | |

0 dB | 9.33109 | 15.8195 | 10.8239 | 21.1769 |

5 dB | 11.1558 | 27.0993 | 12.1698 | 42.7428 |

10 dB | 14.3648 | 58.0264 | 19.2917 | 60.2544 |

15 dB | 22.5041 | 69.4254 | 36.3608 | 73.5611 |

**Table 3.**PSNR values for FFT-OFDM and DCT-OFDM for QPSK with MRC (nTx = 1 and nRx = 1, 2) over AWGN Channel.

SNR | FFT-OFDM | DCT-OFDM | ||
---|---|---|---|---|

1 Tx and 1 Rx | 1 Tx and 2 Rx | 1 Tx and 1 Rx | 1 Tx and 2 Rx | |

0 dB | 9.9119 | 16.0626 | 10.4111 | 21.2002 |

5 dB | 11.5252 | 26.9213 | 12.8423 | 44.3806 |

10 dB | 13.0074 | 59.5812 | 17.4532 | 62.5781 |

15 dB | 23.8034 | 70.2641 | 29.1656 | 76.5459 |

**Table 4.**PSNR values for FFT-OFDM and DCT-OFDM for 8-PSK with MRC (nTx = 1 and nRx = 1, 2) over AWGN Channel.

SNR | FFT-OFDM | DCT-OFDM | ||
---|---|---|---|---|

1 Tx and 1 Rx | 1 Tx and 2 Rx | 1 Tx and 1 Rx | 1 Tx and 2 Rx | |

0 dB | 9.2832 | 12.5852 | 9.5323 | 13.5347 |

5 dB | 10.309 | 18.1539 | 10.616 | 20.5674 |

10 dB | 12.3526 | 32.8267 | 12.5531 | 42.1449 |

15 dB | 16.4483 | 59.4964 | 16.747 | 64.5412 |

**Table 5.**PSNR values for FFT-OFDM and DCT-OFDM for 16-PSK with MRC (nTx = 1 and nRx = 1, 2) over AWGN Channel.

SNR | FFT-OFDM | DCT-OFDM | ||
---|---|---|---|---|

1 Tx and 1 Rx | 1 Tx and 2 Rx | 1 Tx and 1 Rx | 1 Tx and 2 Rx | |

0 dB | 10.944 | 18.0643 | 11.688 | 20.7696 |

5 dB | 11.7248 | 22.4797 | 13.3363 | 25.7564 |

10 dB | 16.9373 | 28.995 | 20.5709 | 36.2319 |

15 dB | 21.3388 | 45.3092 | 24.427 | 70.0577 |

**Table 6.**PSNR values for FFT-OFDM and DCT-OFDM for BPSK with MRC (nTx = 1 and nRx = 1, 2) over Rayleigh Channel.

SNR | FFT-OFDM | DCT-OFDM | ||
---|---|---|---|---|

1 Tx and 1 Rx | 1 Tx and 2 Rx | 1 Tx and 1 Rx | 1 Tx and 2 Rx | |

0 dB | 8.5157 | 12.78663 | 10.1498 | 16.5133 |

5 dB | 10.1206 | 18.3998 | 11.7852 | 26.032 |

10 dB | 12.9643 | 34.54 | 15.559 | 56.4358 |

15 dB | 18.8008 | 54.3651 | 22.734 | 72.1541 |

**Table 7.**PSNR values for FFT-OFDM and DCT-OFDM for QPSK with MRC (nTx = 1 and nRx = 1, 2) over Rayleigh Channel.

SNR | FFT-OFDM | DCT-OFDM | ||
---|---|---|---|---|

1 Tx and 1 Rx | 1 Tx and 2 Rx | 1 Tx and 1 Rx | 1 Tx and 2 Rx | |

0 dB | 9.6355 | 12.8861 | 9.9624 | 15.7346 |

5 dB | 10.5961 | 18.7141 | 12.1718 | 26.1021 |

10 dB | 19.331 | 34.0961 | 15.009 | 61.4828 |

15 dB | 19.037 | 53.1652 | 27.8149 | 76.5221 |

**Table 8.**PSNR values for FFT-OFDM and DCT-OFDM for 8-PSK with MRC (nTx = 1 and nRx = 1, 2) over Rayleigh Channel.

SNR | FFT-OFDM | DCT-OFDM | ||
---|---|---|---|---|

1 Tx and 1 Rx | 1 Tx and 2 Rx | 1 Tx and 1 Rx | 1 Tx and 2 Rx | |

0 dB | 9.2219 | 10.9362 | 9.228 | 11.4612 |

5 dB | 9.8334 | 13.8928 | 10.0164 | 15.2007 |

10 dB | 11.2669 | 21.5332 | 11.4974 | 25.1824 |

15 dB | 14.2133 | 43.1082 | 15.151 | 49.9177 |

**Table 9.**PSNR values for FFT-OFDM and DCT-OFDM for 16-PSK with MRC (nTx = 1 and nRx = 1, 2) over Rayleigh Channel.

SNR | FFT-OFDM | DCT-OFDM | ||
---|---|---|---|---|

1 Tx and 1 Rx | 1 Tx and 2 Rx | 1 Tx and 1 Rx | 1 Tx and 2 Rx | |

0 dB | 10.4532 | 15.135 | 10.9457 | 17.853 |

5 dB | 11.7834 | 19.6491 | 13.9493 | 22.3086 |

10 dB | 14.6304 | 24.1127 | 18.4043 | 28.286 |

15 dB | 20.1877 | 32.447 | 22.2489 | 43.1996 |

**Table 10.**PSNR and SSIM variations for FFT-OFDM and DCT-OFDM for QPSK with MRC (nTx = 1 and nRx = 1, 2, 3) over Rayleigh Channel for RGB image (Baboon).

System | Antenna Configuration | SNR = 0 dB | SNR = 5 dB | SNR = 10 dB | SNR = 15 dB | ||||
---|---|---|---|---|---|---|---|---|---|

PSNR | SSIM | PSNR | SSIM | PSNR | SSIM | PSNR | SSIM | ||

FFT-OFDM | 1 Tx and 1 Rx | 9.76543 | 0.03915 | 10.705663 | 0.07199 | 11.58676 | 0.111477 | 15.3062 | 0.2962 |

1 Tx and 2 Rx | 11.9468 | 0.12827 | 15.321285 | 0.3044454 | 23.93093 | 0.775219 | 51.2156 | 0.9994 | |

1 Tx and 3 Rx | 13.2219 | 0.1910 | 18.5414 | 0.4963 | 32.5573 | 0.9624 | 73.2458 | 1.0000 | |

DCT-OFDM | 1 Tx and 1 Rx | 9.67864 | 0.04332 | 9.6975001 | 0.0227244 | 14.11069 | 0.236522 | 20.5423 | 0.6079 |

1 Tx and 2 Rx | 13.5783 | 0.2069 | 19.38939 | 0.545288 | 35.45733 | 0.980889 | 78.4622 | 1 | |

1 Tx and 3 Rx | 15.8745 | 0.3314 | 25.2924 | 0.8255 | 56.8592 | 0.9998 | 87.5695 | 1.0000 |

**Table 11.**PSNR and SSIM variations for FFT-OFDM and DCT-OFDM for QPSK with MRC (nTx = 1 and nRx = 1, 2, 3) over Rayleigh Channel for grayscale image (Lena).

System | Antenna Configuration | SNR = 0 dB | SNR = 5 dB | SNR = 10 dB | SNR = 15 dB | ||||
---|---|---|---|---|---|---|---|---|---|

PSNR | SSIM | PSNR | SSIM | PSNR | SSIM | PSNR | SSIM | ||

FFT-OFDM | 1 Tx and 1 Rx | 9.89905 | 0.0293 | 10.592833 | 0.0430585 | 11.81925 | 0.085431 | 15.504 | 0.21941 |

1 Tx and 2 Rx | 12.0372 | 0.0938 | 15.224939 | 0.211088 | 23.72912 | 0.646574 | 48.3271 | 0.99792 | |

1 Tx and 3 Rx | 13.2472 | 0.1336 | 18.4498 | 0.3581 | 32.2927 | 0.9355 | 72.4842 | 1.0000 | |

DCT-OFDM | 1 Tx and 1 Rx | 10.2949 | 0.0411 | 11.182142 | 0.0651304 | 12.34516 | 0.119801 | 18.1675 | 0.33916 |

1 Tx and 2 Rx | 13.5942 | 0.1467 | 19.413126 | 0.4074441 | 35.84002 | 0.964057 | 78.6842 | 1 | |

1 Tx and 3 Rx | 15.8437 | 0.2359 | 25.1688 | 0.7168 | 48.3627 | 0.9988 | 85.9384 | 1.0000 |

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**MDPI and ACS Style**

Kansal, L.; Gaba, G.S.; Chilamkurti, N.; Kim, B.-G.
Efficient and Robust Image Communication Techniques for 5G Applications in Smart Cities. *Energies* **2021**, *14*, 3986.
https://doi.org/10.3390/en14133986

**AMA Style**

Kansal L, Gaba GS, Chilamkurti N, Kim B-G.
Efficient and Robust Image Communication Techniques for 5G Applications in Smart Cities. *Energies*. 2021; 14(13):3986.
https://doi.org/10.3390/en14133986

**Chicago/Turabian Style**

Kansal, Lavish, Gurjot Singh Gaba, Naveen Chilamkurti, and Byung-Gyu Kim.
2021. "Efficient and Robust Image Communication Techniques for 5G Applications in Smart Cities" *Energies* 14, no. 13: 3986.
https://doi.org/10.3390/en14133986