Moving towards IoT Based Digital Communication: An Efficient Utilization of Power Spectrum Density for Smart Cities  
[PERSON]  
1 Electrical Engineering Department, College of Engineering, Najran University, Najran 61441, Saudi Arabia; [EMAIL_ADDRESS] (A.S.A. ); [EMAIL_ADDRESS] (M.I. )1 Electrical Engineering Department of Computer Science, Punjab Education System, Depaalpur 56180, Pakistan; [EMAIL_ADDRESS] Department of Computer Science, Faculty of ICT, Balochistan University of Information Technology Engineering and Management Sciences, Quetta 87300, Pakistan; ahthasham.sajid@buitms. the stability of service quality is to use a modulation technique, which authenticates the regulation of the signal pattern that depends on the signal-to-noise ratio (SRN) condition. Lower-order modulation can be used to maintain stability in case the channel condition is not good. Many digital conversion techniques have been proposed in the era of data communication to modulate the signal into waveform. These techniques are based on different signal modulation patterns. These techniques have their pros and cons for digital transmission. Some of them perform better against bandwidth utilization and rest for the power spectrum density (PSD) and direct current (DC) components. The signal format minimizes the effect of noise during message transmission. The choice of specific line code is based on its nature of the signal format [1; 2]. The most valuable property of line code is PSD and the usage of bandwidth during signal transmission. The PSD shows the distortion of a signal in response to frequency. The ideal frequency of a signal ensures that the adopted line code does not have a DC component issue [3; 4]. The primary purpose of a line code to transmit signals from one location to others should be less effect of noise and inter-symbol interference (ISI). The solution to ISI is also to increase bandwidth. It is not an excellent solution to save the useful resource of bandwidth [5; 6]. The line code allows handling of this issue to decrease ISI, and it is also possible to use PSD at an ideal level. The different digital-to-digital line code schemes are shown in Figure 1. However, none of the single digital modulation techniques are available to meet the requirement of IoT devices to connect them with digital communication. Therefore, there is a need to design a modulation technique that provides low PSD and better utilization of bandwidth without DC components. Existing techniques can deal with the specific nature of the problems, and with communication platforms, as with encoding techniques, some are proposed to deal with short-range and others with long-range communication. However, in the emerging field of IoT and smart technology, both types of communication are needed. The methods are used for the conversion of different kinds of signals into another form of a signal, which itself poses critical issues in communication. Because of analog-to-digital signal conversion, the data rate becomes high, and more transmission bandwidth is required for digital communication. The synchronization in digital communication is another problem that arises due to conversion methods in the case of synchronous modulation. This work is the extension of [2]. In this paper, we propose the Shadow Encoding Scheme (SES), which modulates the signal of audio, video, and text messages into a waveform using a low PSD and without consuming high bandwidth for short- and long-range communication. SES is also able to resolve the problem of synchronization and DC components by using the shadow copy of the same  
Figure 1: Digital encoding techniques. repeating bits in the communication. During the programming of the SES, the digital binary string \"11110000101\" is used to obtain the results for comparison with other modulation schemes. The same string of bits is used for other digitizing schemes to obtain the results for bandwidth, synchronization and DC component.