Design and implementation of a v2x tag for iot based smart on street parking system

2021 8th NAFOSTED Conference on Information and Computer Science (NICS) Design and Implementation of a V2X-Tag for IoT-Based Smart On-Street Parking System 1st Vinh Tran-Quang, Member, IEEE, 2nd Duc Nguyen-Dinh School of Electrical and Electronic Engineering (SEEE) Hanoi University of Science and Technology, Vietnam vinh.tranquang1@hust.edu.vn School of Electrical and Electronic Engineering (SEEE) Hanoi University of Science and Technology, Vietnam duc.nd167138@sis.hust.edu.vn Abstract—In this paper, we propose to design and develop a device called V2X-Tag with compact dimensions suitable for mounting on vehicles such as cars, allowing these cars to communicate with each other through a mobile cellular network We also develop firmware for the V2X-Tag and propose a communication protocol between the V2X-Tag and Server We also built prototypes of the V2X-Tag and tested these devices in a smart street parking management system The test results show that, with low power consumption, the V2X-Tag proposed in this paper is suitable for use in IoT systems such as street parking management systems Index Terms—C-V2X-Tag, IoT system, mobile communication, parking system, wireless network I I NTRODUCTION V2X stands for Vehicle to Everything, is a communication system that supports the exchange of information between vehicles and other entities in the system that can affect vehicles such as other vehicles, traffic lights, infrastructure, or any entity equipped with V2X technology [1], [2] The goal of V2X technology is to improve road traffic safety, save energy, and improve traffic efficiency Communication between entities in the system requires high accuracy and reliability By sharing information, such as speed and direction with objects around the vehicle, V2X technology improves the driver’s awareness of potential hazards on the road, helping the driver to know and be aware of the traffic situation ahead, helping to minimize the possibility of traffic accidents [3], [4] The obvious benefits of the V2X technology are alerting drivers of upcoming road conditions, suggesting alternative routes to avoid traffic congestion, and identifying available street parking The V2X technology is developing in two directions [2], [5]: V2X based on the LTE/5G mobile communication network infrastructure (C-V2X) and V2X based on IEEE802.11p technology (DSRC) [6] In particular, C-V2X technology [7], [8] is considered the strongest development direction in the future, especially when 5G technology will be used as an inevitable trend in the 4.0 era However, in Vietnam, up to now, the 5G network is still in the research and development stage and has not yet provided commerce services Therefore, in this paper, we choose the C-V2X technology based on the LTE mobile communication network to develop a V2X tag mounted in the car, which serves as a smart parking management system on the street Developed for both short-term deployment and long-term development, 978-1-6654-1001-4/21/$31.00 ©2021 IEEE C-V2X is flexible enough to support both today’s use cases and future use cases Compatible with 4G and 5G mobile networks, it is designed to be scalable and interoperable Over time, C-V2X will support advanced driver assistance systems (ADAS), where vehicles can cooperate, coordinate, and share the information collected by sensors and ultimately drive the connected vehicle autonomous vehicle (CAD) [1]–[3], [9] In this paper, our aim is to design and develop a device called V2X-Tag with compact dimensions suitable for mounting on vehicles such as cars, allowing these cars to communicate with each other through a mobile cellular network At the same time, we also develop firmware for the V2X-Tag and propose a communication protocol between the V2X-Tag and Server We also built prototypes of the V2X-Tag and tested these devices in a smart street parking management system (sParking) The actual test results show that the V2X-Tag works well and meets the designed technical requirements, providing accurate information about parking location (parking slot), parking time, vehicle identification, etc., serving the functions of parking management, parking space notification, route navigation, and service charge II LTE-BASED V2X-TAG H ARDWARE D ESIGN A Technical Requirements To manage the smart parking spot system on the street, registered cars that use the service will be fitted with a V2XTag device Since the V2X-tag device uses the vehicle’s power via the USB port, when the vehicle is turned off, the device’s power supply is cut off Therefore, when the vehicle enters / exits the parking spot, the user needs to press the register / release button on the device to confirm the time to start using the parking slot or end using the parking slot When the register/release button on the tag is pressed, the tag will send user information (including the tag’s ID, the time to start using the slot / time to end the use of the slot, the location of the slot, etc.) to the system via the 4G LTE module Requires the V2X-Tag to be equipped with a touch-sensitive button to communicate with the user The user will press and release this button to notify the car entering the parking slot and hold the button (about 1.5 seconds) to notify the car out of the parking lot The V2X-Tag will have two main data transmission interfaces: transmitting and receiving data by SIM7600 [10] module and by WiFi via ESP32 module 446 2021 8th NAFOSTED Conference on Information and Computer Science (NICS) The ESP32 module in V2X-Tag acts as the main controller of the tag and plays the role of transmitting and receiving data The V2X-Tag is time-synchronized via LTE network and is located using the built-in GPS receiver on the SIM7600CE module The management center (Server) will listen for socket connection requests to receive messages from V2X-Tag, save them in the database, process the messages, and return ACKs for the tag with the respective use cases application The server data are accessible by authorized user applications Such data may be used by third parties to analyze, design, and develop related applications V2X-Tag uses a 5V USB power source that plugs directly into the car, so it requires a compact V2XTag design and saving power consumption The V2X-Tag is plugged into the car, so it will likely affect the GPS data capture function, so V2X-Tag needs to design a loose V2XTag cover, leaving the GPS antenna part open to minimize the case of failure to get GPS In summary, the technical requirements for V2X-Tag in this project include: • • • • • USER Interface LED state, Button • • UART LTE MODULE SIM7600CE-M1S Typ 3V8 Power Supply Fig Block Diagram of the V2X – Tag C Design Layout and Sample Product Images Due to the compactness requirements of the V2X-tag, we design the V2X-Tag board as two separate subboards and then connect them on top of each other via jumps • MCU & Touch sub-board: includes ESP32, buttons, LED status display, flash, shift level IC, and 5V power converter block from the USB port in the vehicle to 3V3 • 4G & Power sub-board: includes SIM7600CE module, 5V to 3V8 power converter block The PCB layout image and the 3D product image from the design software are shown in Figure Figure is the image of the V2X tag prototypes after they are manufactured and assembled Has touch buttons and status LED Communicate with Server via LTE/WiFi Has GPS navigation 5V USB power supply Compact size, suitable for car mounting III C OMMUNICATION P ROTOCOL B ETWEEN V2X-TAG AND S ERVER With the above functional requirements, we propose a general diagram of the LTE-based V2X-Tag, as shown in Figure 1, consisting of the following main blocks: • MCU ESP32-D0WDQ6 Typ 3V3 B Block Diagram Design • GPIO A Design Message Structure We propose to design the message structure and communication protocol between the V2X-tag and the monitoring center (Server) as follows The server and the V2X-Tag device exchange information with each other using encrypted TCP/UDP packets through the LTE SIM7500E module The maximum packet size is 64 bytes, consisting of two parts: SIGN (header) and MESSAGE as depicted in Figure and Table I To determine whether the message exchanged between the V2X-tag and the Server is a data message or an ACK message, we rely on the MTI (Message Type Identifier) field as defined in Table II To reduce transmission costs and save energy, the data packet is transmitted only according to events when a vehicle approaches the parking slot or leaves the parking lot Data messages with payload containing the information described in Table III The entry / exit status of the parking slot or the server processing status will be encapsulated in the STATE field as defined in Table IV and Table V, respectively Power block: The device’s power block performs the function of converting 5V power from the USB connection port to lower voltage levels such as 3V3 and 3V8 The power block is required to operate stably and meet the necessary amperage for the operation of hardware modules Communication block: The communication block uses the SIM7600CE module to send/receive data between the system and the device The main function of the LTE radio communication block in V2X-Tag is to send user data and receive system control commands In this paper, we use the SIM7600CE module of SIMCOM [10] The SIM7600CE module has the appropriate specifications for V2X-Tag in the smart parking system Control block: The control block uses the ESP32 microcontroller, which controls the reception of user data, encapsulates data, controls the LTE module, and performs control of the device’s operations At the same time, it also plays the role of a WiFi communication module User interaction block: This block includes one touch button and LEDs that show device status (status of 4GLTE and WiFi, GPS, and parking register or release), parking suggestion, parking confirmation B Operation Mechanism Communication on V2X-Tag is designed to be event-driven When connecting the V2X-Tag to the 5V power source via the car’s USB port, the LED LTE and LED GPS RED lights are turned on and the SIM7600 module starts During the booting process, LED LTE will blink continuously and will only stop blinking when the SIM module is successfully started The Within the scope of this paper, we not present the detailed schematics of the V2X-Tag’s principle design 447 2021 8th NAFOSTED Conference on Information and Computer Science (NICS) Top layer Bottom layer Top layer (a) Bottom layer (b) Fig The PCB layout of (a) 4G & Power board and (b) MCU & Touch board Fig Image of the V2X tag prototypes SIGN (4 bytes) SEQ (4 bytes) Undefine Value (6 bits) TABLE I D EFINES THE STRUCTURE OF MESSAGES EXCHANGED BETWEEN V2X-TAG AND S ERVER (LTE PACKET ) MESSAGE (60 bytes) MTI (1 byte) DATA (1 bit) ID/IMEI (15 bytes) ACK (1 bit) LAT (11 bytes) DATA (40 bytes) LONG (12 bytes) DATE (8 bytes) TIME (8 bytes) STATE (1 byte) Field Name Description SIGN SEQ MTI ID/IMEI DATA Mark the start of the message Sequence number of messages Specify Data/ACK message type Device ID or IMEI string Raw data payload Length (bytes) 15 60 Fig Message Structure (RAW DATA) the LED LTE light will turn off (preferably using WiFi to transmit and receive data) The status of the LEDs on the V2X-Tag and their meanings are defined as shown in Figure The operation flow of the V2X-Tag in the smart parking device is then ready to operate V2X-Tag will search for WiFi access points every seconds If V2X-Tag can connect to WiFi to access the Internet, the LED WiFi will light up and 448 2021 8th NAFOSTED Conference on Information and Computer Science (NICS) RED: active LTE (no WiFi) TABLE II MTI FIELD DEFINITION BLUE: WIFI ON (inactive LTE) GPS_RED: no GPS Bit Order 2–7 Description Sending Direction GPS_BLUE: good GPS signal ACK: Acknowledgment DATA: Send data Undefined Downlink (Server to V2X-Tag) Uplink (V2X-Tag to Server) Future use LED_PARK_RELEASE LED_PARK_REGISTER TABLE III DATA FIELD DEFINITION Field Name Description LAT LONG DATE TIME STATE Latitude of the device Longitude of the device Message sending date Message sending time Processing status (depends on MTI) Length (bytes) Fig LEDs status on the V2X-Tag and their defined meanings 11 12 8 V2X-TAG VEHICLE IN CLICK IN [parameters] SERVER SIGN, SEQ, MTI, ID, LAT, LONG, DATE, TIME, STATE SIGN, SEQ, MTI, ID, STATE TABLE IV D EFINES THE STATE FIELD OF UPLINK LED NOTIFY (V2X-TAG TO S ERVER ) VEHICLE OUT STATE Description SIGN, SEQ, MTI, ID, STATE LED NOTIFY TABLE V STATE FIELD OF DOWNLINK TO V2X-TAG ) Description Vehicle exit parking slot Vehicle entry parking slot V2X-Tag is not registered in the system Parking slot are not in the system system is described in Figure As shown in Figure 6, the operation of V2X-Tag in the IoTbased smart street parking system is divided into phases: the search for space and the drive into the parking lot (VEHICLE IN) and the exit from the parking phase (VEHICLE OUT) VEHICLE IN: Register parking slot process: • SIGN, SEQ, MTI, ID Fig The operation flow of the V2X-Tag in the smart parking system (S ERVER • • SIGN, SEQ, MTI, ID, LAT, LONG, DATE, TIME, STATE [parameters] Vehicle exit notification (slot release / unoccupied) Vehicle entry notification (slot register / occupied) D EFINES THE STATE CLICK OUT SIGN, SEQ, MTI, ID When there is a need to park on the street, the user, with a V2X-Tag device registered on the system and connected to the car’s USB power port, opens a sParking application on a smartphone (the sParking application is not present in this paper) to search for the nearest available slot When the user approaches the parking slot, the V2X-Tag compares its GPS coordinates with the coordinates of the parking slot that is predefined in the parking spot management system If it matches, the device will issue a parking confirmation message by turning the LED GPS GREEN status to green and waiting for the user to confirm When LED GPS GREEN is on, the user presses and releases the register/release button on the V2X-Tag, LED PARK REGISTER will flash continuously for second, indicating that the user has pressed the request button, a data message will be generated and send it to the server The data message includes the device’s ID, vehicle location, the date, and time of sending Server receives the data message sent from the V2X-Tag, will authenticate the user, and checks the validity of the received message Next, the Server will generate and send an ACK message to V2X-Tag for confirmation During a predefined timeout period, if the tag receives an ACK message, LED PARK REGISTER will turn on, meaning parking is successful V2X-Tag saves GPS location and other status information to its internal memory If no ACK is received the LED PARK REGISTER will turn off The user needs to press the touch button to send the parking request again VEHICLE OUT: Release parking slot process: • • 449 When the user starts the vehicle engine, the V2X-Tag is also booted and reloaded with the previous status information (parking success status) To end the parking session, the user presses and holds the register/release button for about seconds, the LED PARK RELEASE light will flash continuously for seconds to confirm that the user has just pressed the request button to get out of the parking lot, a data message 2021 8th NAFOSTED Conference on Information and Computer Science (NICS) will be generated and send to the Server including the vehicle location, the date and time of sending the message If sending is successful, LED PARK RELEASE will be lit If it fails, the LED PARK RELEASE will turn off Users must press the touch button to send a request to end the parking session again device receives the message within the timeout period, and it will proceed to process the packet The device first checks the SIGN (@V2X - Device Identifier), and ID/IMEI (Device Identifier), CMD ID (MTI) fields The communication between the device and the server will end when the V2X-Tag sends an ACK packet to the server C Data Processing Procedures Start The data processing process is shown in Figure In which the main functions/procedures to process data include: • secure_encrypt(): Encrypt the data block to be sent with the predefined secret key “sPKGPWD”, corresponding to each device With V2X-Tag, the key is stored in the firmware of the V2X-TAG In Server, the key is stored in the database The authentication function checks the secret key match in V2X-Tag and Server • base85_encode(): Data are encoded with the BASE85 method to convert all binary data to text, suitable for communication with the GSM/GPRS/LTE modem • pack_data(): Pack data according to the LTE Packed standard • send_data(): Procedure for sending data • receive_data(): Procedure for receiving data (which is an LTE packed block) • base85_deccode(): Decode with the BASE85 method to convert data from text to binary • secure_decrypt(): Decryption with the secret key “sPKGPWD” • process_data(): Process the original data received New period has started Normal State YES Register/ Release? Release Register Packing Data Encrypted Data Start Tx, Led warning Start Rx, Wait for ACK Encrypted (ARC-4) Text (Base 85) Encrypted (AES) ID/IMEI? YES Cond? LTE Packed (Send) Text (Base 85) Decrypted (ARC -4) Time out? NO YES Decrypted Data STATE? Decrypted (AES) NO NO Msg? (a) Process of sending data LTE Packed (Received) YES SIGN? MTI? DataParked (RAW Pack) NO Event? Excute & send ACK New period has started DataPacked (RAW Pack) End (b) Process of receiving data Fig Flowchart of the V2X-Tag Communication Algorithm Fig Process of handling data sent/received via LTE Module IV T EST R ESULTS D Flowchart of the V2X-Tag Communication Algorithm A Power Consumption Evaluation The V2X-Tag device in the sParking system uses the 4G LTE communication standard to exchange data with the server The flowchart of the V2X-Tag communication algorithm is illustrated in Figure The following events will trigger V2XTag to send packets to the Server: • The device enters the parking lot • The device leaves the range of the parking lot • The user presses the register/release parking button At the end of the data sending phase, the device establishes a receive window for a pre-configured fixed period of time to wait for an ACK or ACK + CMD response from the Server If the timeout period has passed but the ACK has not been received, the device will proceed to re-send the packet The The power consumption tests of the V2X-Tag used a GW Instek GPS 4-channel DC output power supply (30V, 3A, 4CH) When starting to supply 5V power to V2X-Tag, the SIM7600 module performs network registration This is the highest power consumption process of V2X-Tag, the measured current is 280mA Power consumption is P = U I = × 0.28 = 1.4W After successful network registration, the current consumed in the V2X-Tag will gradually decrease to the waiting state for user interaction At this time, the power consumption of V2X-Tag reaches the minimum value; the measured current consumption is 40 mA Power consumption is P = U I = × 0.04 = 0.2W When the user starts interacting with the V2X-Tag by pressing the touch button, 450 2021 8th NAFOSTED Conference on Information and Computer Science (NICS) the process of sending a confirmation message will be sent to the server and waiting for the ACK message This process consumes more power than the standby state, the measured current value is 120 mA, corresponding to the power consumed in the active state (sending/receiving data) of V2X-Tag is P = U I = × 0.12 = 0.6W The user will press and hold the touch button on the V2XTag for about 1.5 seconds to send a request to confirm the removal of the vehicle, a message will be sent to the server as shown in Figure 10 (b), message number 264 After successful registration, an ACK message from the server returns the V2XTag to acknowledge the server has received the message At the same time, on the V2X-Tag, LED PARK REGISTER will turn off, and LE PARK RELEASE will be red (Figure (c)) The sending process is over B Field Test Results The experimental deployment takes place at the parking lot location at latitude 21.192401, longitude 105.825735 Parking radius is 200 meters along the street As the LED signaling system function is described in Figure 6, the LED status after it has been started and GPS data has been obtained is shown in Figure (a) The WiFi light is green, the GPS light is on, and the LED that has not sent the vehicle is red (a) (b) V C ONCLUSION In this paper, we have proposed the design and prototype manufacture of the V2X-Tag, proposed to develop the firmware, and design the radio communication protocol for the V2X-Tag device V2X-Tag prototypes have been tested and evaluated for power consumption, communication, and parking registration, parking release activities in the on-street smart parking management system The test results show that, with low power consumption (0.2W in standby mode and 0.6W in data sending/receiving mode, respectively), the proposed V2XTag is suitable for use in IoT systems such as street parking systems The proposed V2X-Tag is also suitable for extending use to other V2X applications in the future (c) ACKNOWLEDGEMENT This work was supported by Vingroup Innovation Foundation (VINIF) under Project VINIF.2019.DA16 Fig Image of V2X-Tag in action during a field test: (a) Standby state when GPS position is obtained, (b) Successfully sending a start parking request, and (c) Successfully sending a stop parking request R EFERENCES STT SysTime SIGN SEQ MTY 263 27-06-2021 23:26:16 @V2X ID LAT LONG DATE TIME 000000000012345 21.19247442 105.82557962 28/06/21 06:26:16 [1] K Abboud, H A Omar, and W Zhuang, “Interworking of dsrc and cellular network technologies for v2x communications: A survey,” IEEE Transactions on Vehicular Technology, vol 65, no 12, pp 9457–9470, 2016 [2] S Maaloul, H Aniss, M Kassab, and M Berbineau, “Classification of c-its services in vehicular environments,” IEEE Access, vol 9, pp 117 868–117 879, 2021 [3] S Zeadally, M A Javed, and E B Hamida, “Vehicular communications for its: Standardization and challenges,” IEEE Communications Standards Magazine, vol 4, no 1, pp 11–17, 2020 [4] M Xie, S Ramanathan, A Rau, D Eckhoff, and F Busch, “Design and evaluation of v2x-based dynamic bus lanes,” IEEE Access, vol 9, pp 136 094–136 104, 2021 [5] J.-K Bae, M.-C Park, E.-J Yang, and D.-W Seo, “Implementation 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limited: Sim7600 series hardware design,” Available at http://mt-system.ru/sites/default/files/ documents/sim7600 series hardware design v1.07.pdf (accessed on Oct 10, 2021) STATE (a) Register parking request message STT SysTime SIGN SEQ MTY 264 27-06-2021 23:37:08 @V2X 000000000012345 21.19247442 105.82557962 28/06/21 06:37:08 263 27-06-2021 23:26:16 @V2X 000000000012345 21.19247442 105.82557962 28/06/21 06:26:16 ID LAT LONG DATE TIME STATE (b) Release parking request message Fig 10 Register/Release parking request message exchange between V2XTag and Server the LED state before when the car engine was turned off After entering the parking lot, to send a parking request, the user presses and releases the touch button on the V2X-Tag, a message will be sent to the server as shown in Figure 10 (a) After successful sending, an ACK message from the server returns the V2X-Tag to confirm that the server has received the message At the same time, on the V2X-Tag, the LED PARK REGISTER will turn off, and the LED PARK RELEASE will turn green (Figure (b)) At this time, the user can completely turn off the engine and get off the car, the parking status, as well as the parking position will be saved in the EEPROM memory The process of taking the car out is the opposite of the parking process, the user starts the car, V2X-Tag will get the data in the EEPROM to set 451 ... device V2X- Tag prototypes have been tested and evaluated for power consumption, communication, and parking registration, parking release activities in the on- street smart parking management system. .. communications for its: Standardization and challenges,” IEEE Communications Standards Magazine, vol 4, no 1, pp 11–17, 2020 [4] M Xie, S Ramanathan, A Rau, D Eckhoff, and F Busch, ? ?Design and evaluation... Block Diagram of the V2X – Tag C Design Layout and Sample Product Images Due to the compactness requirements of the V2X- tag, we design the V2X- Tag board as two separate subboards and then connect