## 5 Progress of Data Transmission Protocols for Wireless Communication in Solar PV Monitoring Systems
### GSM-Based Module  
The Global System for Mobile (GSM) is generally used for the mobile correspondence framework. The GSM framework is built by utilizing Time Division Multiple Access (TDMA) [112]. The GSM framework is portable with a wide coverage area and has a high consistency [41]. The framework is characterized by distinctive components and the routes in which they communicate to empower the general framework operation. The operation of the GSM includes the communication between a mobile phone and a Public Switch Telephone Network (PSTN). The first GSM framework was propelled in the mid-1990s [113].  
[PERSON] and [PERSON] [114] designed solar PV remote monitoring and control systems with GSM technology and LABVIEW to monitor the parameters and other factors. The system consisted of sensors connected in a star topology and a PIC18F4550 board with an inbuilt 8 KB of flash memory, 368 bytes of Random-Access Memory (RAM) and 256 of Electrically Erasable Programmable Read-Only Memory (EEPROM) The microcontroller programming code was edited with mikroC PRO. The proposed technique could be further enhanced by storing the data in the cloud, detecting the faulty panel by fault detection techniques, and expanding the coverage area. [PERSON] et al. [91] developed a solar power monitoring and control system based on the GSM network for rural areas. The information was transferred to the targeted mobile station through a GSM interface using a Short Messaging Service (SMS). It is suggested that future work focuses on data security which could secure the data sent via Short Message Service (SMS). [PERSON] and [PERSON] [115] presented a GSM-based solar PV monitoring system to control the orientation of the solar panels all year round. The test board consisted of the solar panel, two lead-acid batteriesrated at 6 V, ab ATMEGA328 board, a Steca-Solsum 6.6 F/12, 24 V/6A solar PV panel charge controller, and a two bipolar stepper motor with a torque of 0.23 Nm rated at 12 V. The system was able to follow the sun tracker through the GSM network. The suggested work could be enhanced by obtaining the electrical as well as the environmental parameters to observe the panel condition in conjunction with the control of the orientation of the panel. In their recent work, [PERSON] et al. [116] developed a 4G communication platform to monitor electrical parameters such as voltage and current. Further, the monitoring technology was integrated with a cloud server for the display and monitoring of the extracted data. Further, the presented work designed a feature extraction and a classification model for analysing the health status of the inverter. A probabilistic neural network (PNN) model was designed with the 660 sets of faulty data for training the model from the PV inverter obtained online at 2-8 kW.  
GSM technology has taken a leap in terms of technological advancements with higher numbers of antennas, low error rates, low costs, wide area coverage and monitoring 24/7 [117]. Despite the advancements achieved, GSM lags behind in some issues relating to the sending of the message, such as the interruption of the data and connection problems with emails when many people use the same bandwidth [118]. Furthermore, Subscriber Identification Module (SIM) card cloning may lead to fraud, resulting in the theft of data [119]. The proposed method was used to examine the solar power transferred to the batteries and the temperature conditions for that moment of time.