# Designing and Managing a Smart Parking System Using Wireless Sensor Networks
## 2 Existing Smart Systems for Parking Management
### Linear Protocols  
Linear protocols are self-organization protocols used by wireless sensor nodes that are dispersed in an area of interest (in this case: parking areas) to form and construct a chain topology for collecting all the data detected and transfer them to the base station (Sink). Car park management systems that use these linear protocols include the following:  
In [5], the proposed system is a system that uses two modules: a monitoring module and a reservation and security module. The surveillance module employs the network of wireless sensors to detect available spaces in a parking area, these sensor nodes are installed in each location forming a chain to collect information related to the states of the parking spaces. This information is sent to the car park management centre for efficient use towards the drivers (display of spaces, etc.). The reservation and security module uses the global system for mobile communication (GSM) system whose drivers must send an SMS to reserve their space in the parking. In return, the drivers receive a password with the number of the space in the parking area, so that they can enter and exit with all normality and with all security. In [6], this article is based on the use of networks of wireless sensors whose nodes are infrared sensors that help to detect the presence of cars in parking spaces. The system consists of two modules: a monitoring module and a master module. The monitoring module consists of a ZigBee transmission and reception unit, a liquid-crystal display (LCD), and a peripheral interface controller (PIC) microcontroller which controls the data detected by the infrared sensor. Once the sensor detects the presence of a car, it informs the microcontroller, to display the status of this parking space on the LCD and, afterwards, it sends this data through the ZigBee transmission interface to the master module using a chain topology. The ZigBee technology used in data transmission shows a high performance in terms of energy consumption during wireless communication and is inexpensive to implement. In [7], the system is based on the use of infrared sensors to detect the existence of cars in parking spaces. This system consists of three modules: the first module is the monitoring module which is responsible for the detection of parking spaces by the infrared sensors, and these sensors contain a PIC controller for data processing and a ZigBee system for data transmission using chain topology. The second module is the reservation module composed by a GSM module for the transmission and reception of data via SMS, allowing the reservation of parking spaces. The third module is the security module which uses the password already provided by the system allowing entry and exit only to authorized persons and who have an a priori reservation. The system of reservation based on GSM technology can be saturated with a high solicitation of the spaces of parking by the users, which can negatively affect the proper functioning of the parking system. The proposed system CPF (Car Parking Framework) [8] manages a smart parking system that combines sensors (detection of parking spaces), RFID tags, and readers (parking access authorization, car's location, and prevention against thefts). This system uses a communication model based on the master/slave model between the sensor nodes in the bus mode with a serial cable communication. All nodes send their data to the master via cable, and afterwards it sends the detected data to the sink via a wireless communication. The installation of the serial cable for the communication between the nodes is expensive to implement and it limits the system for a future extension of the parking, which will cause complications in the development of the system. In [9], the proposed system introduces a new smart parking system (SPS) based on the use of the latest technologies, such as WSNs, ZigBee, RFID, and NFC. The WSN constructs a topology in the form of a chain to collect information about available spaces in the parking area.