Comparative performance study of HC-12, nRF24L01, and XBee for vehicular communication

In recent times, the volume of traffic congestion has been rapidly growing on roads. These days the necessity of having safe transportation and journey is essential. Thus, vehicle communication could be a possible solution to enhance safe transit. Vehicular communications provide a wide range of applications with different characteristics, namely vehicle and vehicle (V2V) communications. Every year, traffic accidents kill many people worldwide, and many people have been injured. V2V communication enables vehicles to communicate with each other to provide safety and convenience to drivers. Therefore, this paper explores a direction to develop a conceptual approach to V2V communication with HC-12, nRF24L01, and XBee. The study aims to analyse and evaluate the communication range that may contribute to the future road transportation system.


INTRODUCTION
Road crashes kill many people in the world each year, and many more people are injured.The primary reason for these accidents is a limitation due to situations on the road, which may be due to the brake failure, sudden standstill or distance blackness [1], [2].Furthermore, a delay in the driver's response to events on the roadway could lead to unavoidable consequences [3], [4].Road safety is often improved to ensure that drivers can see the circumstances coming along the road.Hence, this would be possible if the vehicles were communicating with each other.Vehicle and vehicle (V2V) communication is becoming a reality and will provide various services for safety and efficiency [5], [6].In addition, V2V has demonstrated that it can be incorporated into current designed automotive applications.The exchange of information on vehicle mobility and the state of the road between vehicles plays a significant role in the safety of drivers and passengers.A driver can receive information about road conditions and vehicle speeds in the surrounding area in a particular context.This helps the vehicle make better decisions about vehicle control and route.
In another context, when vehicles communicate in real-time, the driver can avoid potential crashes by changing the speed based on the speed of the nearby vehicle [7]- [9].Therefore, this paper explores the communications platform used between vehicles with HC-12, nRF24L01, and XBee.This paper is organised as follows: i) section 2 elaborates on the mechanism of the three modules and related works; ii) the experimental work and outcome are shown in section 3; and iii) in the last section, the conclusion was highlighted.

RELATED WORKS
The HC-12 is a state-of-the-art semi-duplex wireless mode that provides a frequency spectrum of 433.4 to 473.0 MHz.The module is integrated and would use 100 channels at 400 kHz measurement.The maximum module transmitting power is 100 MW, the receivable sensitivity is at a baud rate of 9,600 in the air with -112 dBm, and the communication distance is less than 1,000 meters through open space.The low data rate makes it possible to reach the most rapid communication ranges.There are three types of operation, such as FU1, FU2, and FU3, which can be customised to the various requirements.For energy-saving modes, FU1 and FU2 apply, while for maximum power mode, FU3 is suitable [10]- [14].There are several studies of the HC-12 modules for various purposes, as shown in Table 1.Analyse the phase delay of a propagating wave between two receiver antennas [17] Safety and security of coal mine workers Analyse different parameters and take actions to mitigate all hazards [18] Collision detection robot car model Analyse collision avoidance and maintain a safe distance between cars [19] Vehicle platooning prototype car model Analyse predictive controller and navigation algorithms in longitudinal and path control [20] Vehicle to vehicle communication Analyse to attenuate vehicle noise to some degree and reduce vehicle horn [21] Traffic signal control system Analyse an efficient route with a traffic light for emergency vehicles [22] Vehicle speed proposition system Analyse to reduce accidents and warn drivers of the speed limit at high accident zones [23] Collision prevention and warning system Analyse to reduce collision and damage in circumstances of accidents [24] Motorcyclist intelligent helmet Analyse to decrease violation by riders of traffic rules and cause accidents [25] Smart motorcyclists protection system Analyse to reduce road accidents by riders under the influence of alcohol [26] Toll gate system Analyse to apply contactless transaction overcoming the queue.[27] Electric vehicle telemetry data system Analyse to monitor and acquire onboard telemetry data of the electric vehicle.[28] Street light energy-saving tool Analyse to minimise energy consumption and reduce maintenance of street lights [29] Accident location and traffic management system Analyse to convey a message to the rescue team in the circumstance of road accidents Generally, nRF24L01is a transmitter-receiver module that transmits and receives data on a specific channel frequency.In addition, they should be on the same channel for two or more transmitter-receiver modules to communicate.This channel can vary from 2.4 to 2.525 GHz within the 2.4 GHz (2,400-2,525 MHz) industrial, scientific and medical (ISM) band.Each channel has a bandwidth of less than 1 MHz and 125 available channels.For instance, the nRF24L01 module also can use 125 different channels and has a network of 125 independent modules in a location [30]- [34].Several studies of the nRF24L01 modules are used for various purposes, as shown in Table 2. Analyse transmitting temperature information in the event of exceeded set value [36] Multipurpose radio-controlled car Analyse a transmitter unit in terms of reception accuracy and transmission exactness [37] Vehicle to V2V to infrastructure communication system Analyse to alert of potential hazards or violate action made by drivers [38] Temperature and humidity sensing Analyse to evaluate the power efficiency and reliability of communication [39] Multipurpose wireless sensing Analyse different approach contexts for possible long operation [40] Wireless control car movement Analyse to improve the efficiency of transportation through wireless communication [41] Data collection box tool Analyse temperature values at different environments and alarm abnormal temperatures [42] Quaternion based wireless data transfer Analyse real-time transmission and acquisition of sensor data [43] Automatic gate control system Analyse to avoid the head-on and collision that occur by human negligence [44] Automatic street light control system Analyse to reduce the energy consumption of transmitting information to a base station [45] Inter vehicle collision avoidance system Analyse prototype cars to avoid a collision at road accidents areas [46] Inter vehicle alert system Analyse vehicle communication for reducing accidents due to drivers negligence [47] An autonomous vehicle surveillance system Analyse transmitting data at different road conditions and speeds [48] Motorcyclist smart helmet and blind-spot detection Analyse on warning motorcyclists of potential hazards that can decrease the probability of road accidents [49]  XBee modules are wireless communication modules that are constructed following the Zigbee standard.XBee is an RF module transceiver that uses the IEEE 802.15.4 protocol.The XBee is a modular product design that makes rolling out wireless technology simple and cost-effective.It can be used as a serial replacement or placed in a control mode and configured for various broadcast and mesh network options.The module provides connectivity solutions to wireless endpoints of built-in devices.Xbee has a 2 dBm beam with a sensitivity minimum of -96 dBm.The XBee and XBee-pro radio frequency (RF) modules are built-in solutions providing wireless connectivity solutions.The 3-pin RF modules can be connected directly to the controller, which does not need an encoder or decoder [50]- [54].Several studies have used XBee for various purposes, as shown in Table 3. Analyse the dampness of the air and the level of CO 2 inside the area [62] Wireless control robot for multiple sensors Analyse the measurement and display on a human interaction machine [63] Cost-effective vehicle tracking system Analyse tracking vehicles in various environments regardless of obstacles.[64] Wireless sensor network for environmental monitoring Analyse transmitting data in real-time and observe the power consumption [65] Smart parking infrastructure system Analyse on detecting the presence of a vehicle and transmit data to the gateway [66] Driver assistance system Analyse on automation process of the driving system to avoid drivers' negligence [67] Automatic traffic control for an ambulance Analyse on determining the traffic congestion and provide smooth route direction [68] Intelligent traffic light system for ambulance clearance Analyse ambulance vehicle movement that can control traffic light flow [69] Traffic management system for emergency vehicle Analyse controlling traffic lights for smooth flow of emergency vehicles

EXPERIMENT AND DISCUSSION
As illustrated in the following subsection, several hardware components were required to interface with the modules in this experiment.

Hardware
The prototype is designed using Arduino Uno integrated separately with three modules such as HC-12, nRF24L01 and XBee.The ultrasonic sensor works along with the modules to detect the range of vehicles for a potential collision.Any alert is indicated in the form of an audible buzzer and visible light emitting diode (LED).The equipment component specifications are presented in Table 4.

Settings and implementation
The performance analysis of three modules is restricted to a controlled environment, as shown in Figure 1.In accordance with the information presented in the preceding section, each testing setting has been established appropriately with the modules.The initial configurations would use HC-12, then nRF24L01, and finally XBee. Figure 2 shows the initial prototype designed to be tested in the given controlled environment settings.

Discussion
The testing for the HC-12, nRF24L01, and XBee module (three device sets) has been analysed in a controlled environment at Taman Dahlia, Bukit Beruang, Melaka.This testing phase is performed to observe the performance in terms of distance/range for potential collision use cases.The testing is directed with having the three separate HC-12, nRF24L01 and XBee modules with various distances connected to a 9 V battery placed in the range/distance discussed.These findings are presented in Tables 5-7.

CONCLUSION
Vehicular communication is a promising field for the road transportation system.However, the primary concern is addressing the communication medium between vehicles.In this paper, the project aims to provide a conceptual communication medium between multiple nodes.Thus, several modules, namely HC-12, nRF24L01, and Xbee, were used to analyse.The results acquired by observation, HC-12 and XBee work on wider distances than nRF24L01.In the future, the research will be compared with ESP8266 and LoRa and evaluate performance metrics, namely throughput, delay, jitter, and packet loss.

Table 2 .
nRF24L01 related studies Motorcyclist smart helmet accident detection Analyse sending messages to immediate family members if accidents have occurred.