Visible light communication (VLC), which is a prominent emerging solution that complements the radio frequency (RF) technology, exhibits the potential to meet the demands of fifth-generation (5G) and beyond technologies. The random movement of mobile terminals in the indoor environment is a challenge in the VLC system. The model of optical attocells has a critical role in the uniform distribution and the quality of communication links in terms of received power and signal-to-noise ratio (SNR). As such, the optical attocells positions were optimized in this study with a developed try and error (TE) algorithm. The optimized optical attocells were examined and compared with previous models. This novel approach had successfully increased minimum received power from −1.29 to −0.225 dBm, along with enhanced SNR performance by 2.06 dB. The bit error rate (BER) was reduced to

As projected by Cisco, the demand for high data rate communication systems has been escalating on daily basis [

The distribution of many small optical attocells in indoor environments should satisfy the requirements of 5G applications due to enhanced channel capacity, transmission rate, and signal-to-noise ratio (SNR) performance, as well as reduced bit error rate (BER) [

The layout of optical attocells plays a crucial role in the indoor VLC system, especially to ascertain the uniform distribution of received power and SNR over the communication plane [

Alternatively, numerous optical attocell configurations were investigated with a range of parameters for indoor setting [

Another potential solution is to use a developed artificial fish swarm algorithm to optimize the positioning of optical attocells in a typical room, which resulted in better communication performance [

The VLC system, which has been considered as a Non-Line of Sight (LOS) channel, was evaluated using a new approach [

Proposing new optical attocells positioning on the room ceiling by using a developed try and error (TE) algorithm.

Extracting new mathematical formulas to solve the problem of maximizing and minimizing performances of several parameters, such as received power, SNR, and BER.

Reducing the BER using OOK-NRZ and BPSK modulation techniques.

Improving uniform distribution in the entire room.

Obtaining higher minimum received power and SNR in the room.

The remainder of this paper is as follows: Section 3 presents the proposed system model and TE algorithm. Next, Section 4 discusses the VLC system parameters, including horizontal illuminance, received power and SNR distribution, modulation techniques, and coefficient of variation (CV). Then, Section 5 presents the simulation results and discussion. This paper is concluded in Section 6.

The primary goal of this study is to maximize the received power and SNR distribution, as well as to reduce BER. Hence, an optimization positions (i.e., TE) algorithm for optical attocells in a standard room model was developed. The mathematical formulation of the maximization and minimization problems is expressed in the following:

Such that

where

Furthermore, the optimization positions should maximize the uniform distribution (CV) in terms of received power and SNR, as given below:

Such that,

The optical attocells deployment of Model 1 is described in [

In Model 1, the separation distance between the optical attocells at the room corners is 2.5 m. However, each optical attocell is separated by 1.25 m from the room edges. In order to improve uniformity, as well as to optimize the minimum received power and SNR, new optical attocells positions with different separation distances were investigated.

Separation at room corners (m) | Separation at room edge (m) | |
---|---|---|

Model 2 | 3 | 1 |

Model 3 | 3.5 | 0.75 |

Model 4 | 4 | 0.5 |

The following lists are the definitions and the flow chart of the TE algorithm, as illustrated in

N = 5% Number of optical attocells within the room

(

(

The maximum result in SNR had reduced the BER, as presented in

Different parameters were employed to evaluate the VLC systems of all optimized models, in terms of illumination, received power, SNR, BER, and CV. The results of all parameters are discussed and analyzed in the following sub-sections.

The geometry system of the standard room model, as illustrated in

The horizontal illumination of 3D points (x, y, and z) is referred to by

The channel DC gain of LOS link is given by

The received power and SNR distribution can be computed respectively as follows:

All previously presented models were further studied by evaluating the BER performance, where the on-off-keying non-return-to-zero (OOK-NRZ) and binary phase-shift keying (BPSK) modulation techniques were deployed in this present study. The BER calculation of both modulation techniques was computed as follows:

The CV is a uniformity metric employed to determine the suitable positions of optical attocells that could be used to provide acceptable communication and illumination performances. Ideal communication quality may be obtained at the lower mean of received power and SNR. The CV of both received power and SNR distribution could be computed respectively as follows:

In order to assess the effect of optical attocells deployment on received power, SNR, and uniform distribution; the simulation was performed for all models.

Received power (dBm) | Model 1 [ |
Model 2 | Model 3 | Model 4 |
---|---|---|---|---|

Maximum | 5.97 | 4.09 | 2.95 | 2.58 |

Minimum | −1.29 | −0.25 | −4.89 | −4.92 |

Average | 2.46 | 2.22 | 1.79 | 1.10 |

CV | 0.62 | 0.45 | 0.57 | 1.39 |

The effect of various SAAHP angles on minimum received power is displayed in

SNR (dB) | Model 1 [ |
Model 2 | Model 3 | Model 4 |
---|---|---|---|---|

Maximum | 81.59 | 77.85 | 75.56 | 74.82 |

Minimum | 67.09 | 69.15 | 59.89 | 59.83 |

Average | 74.58 | 74.10 | 73.24 | 71.87 |

CV | 0.045 | 0.026 | 0.028 | 0.043 |

The results of minimum SNR

To further assess BER, the BPSK modulation technique was applied to explore potential performance improvements.

The BER performance of all models based on OOK-NRZ and BPSK modulation techniques is summarized in

Model 1 [ |
Model 2 | Model 3 | Model 4 | |
---|---|---|---|---|

OOK-NRZ | ||||

BPSK |

Novel optical attocells positions were optimized in this study using a developed TE algorithm with mathematical formulation to enhance the VLC system for a typical room model. Several models were evaluated and the outcomes were compared in terms of received power, SNR, and uniform distribution (i.e., CV). In addition, OOK-NRZ and BPSK modulation techniques were deployed to improve the overall BER performance. Imminently, the optimization model proposed in this study displayed significant improvements in terms of the minimum received power by 80.23% and SNR improvements by 3.1% over the other existing models. Furthermore, the CV values of both received power and SNR were significantly improved by 27.42% and 42.22%, respectively. Besides, reduction of BER using various modulation techniques can successfully deliver reliable communication links especially with BER value below (

The authors acknowledge the funding of this project by the Research Management Centre (RMC), under the Professional Development Research University grant (UTM Vot No. 05E69), Universiti Teknologi Malaysia (UTM), Malaysia. This project was also funded by Universiti Teknologi Malaysia (UTM), under TDR grant Vot No.05G27.