Elsevier

Internet of Things

Volume 5, March 2019, Pages 71-83
Internet of Things

Research article
Binary search tree based hierarchical placement algorithm for IoT based smart parking applications

https://doi.org/10.1016/j.iot.2018.12.001Get rights and content

Abstract

With the increasing numbers of vehicles, the parking space management is becoming a critical issue especially for congested settlement areas. Especially during the peak hours, the difficulty of finding a parking spot can introduce significant challenges to drivers. In order to locate the parking spot, most of the time drivers rely on their own limited knowledge of where the parking spaces are available at a given time. Even in these cases, large numbers of vehicles may try to access limited numbers of parking spaces which in turn leads to traffic congestion. Furthermore, when the parking region is rather complicated with large numbers of spots, the identification of a suitable parking spot becomes an expensive process since it often causes an increase of vehicle traffic which in turn also causes a consequent increase of pollution. Therefore traffic on roads and parking space has been an area of concern in the majority of smart city studies and applications. Parking monitoring is known in the literature as one of the promising solutions to these issues. In this paper, we present a hierarchical approach based on the binary search tree (BST) for parking monitoring systems that helps users to reach a free parking spot easily. The solution proposed introduces an approach which makes searching process in car parking applications efficient in terms of time and energy. Two levels of hierarchy are employed for this purpose. In the first level, our algorithm only checks for the nearest car park. At the second level, the algorithm focuses on the car park that is the nearest and checks the nearest parking spot in that car park. Using this hierarchical approach, the search for an empty spot becomes more time efficient. Simulation results are presented in this study to show the efficiency of the proposed hierarchical approach with BST. Non-hierarchical, hierarchical and hierarchical with BST support approaches are employed for same scenarios in order to show the effectiveness of the new approach. According to simulation results, hierarchical approach with BST is superior in terms of search time and energy efficiency.

Introduction

The parking problem in big cities, has become one of the key causes of the city traffic congestion, driver frustration and air pollution [18]. In the future, it is expected to have an increase in the demand for the intelligent parking services because of the rapid growth in world population as well as the automotive industries. An effective solution to this service can be provided by many new technologies [5]. According to [8], people waste away liters of gas just trying to parking. On average 30% of traffic is caused while looking for an available parking spot. As discussed in [15], drivers waste 3.5–14 min on average to find a parking spot. In addition, it increases traffic congestion, accidents, fuel consumption and air pollution. Smart parking solutions can help to mitigate these problems. This study concentrates on placement algorithms which are used in smart parking applications. Another important factor to take into account is the cases where the location of alternative parking spots are evaluated, for example, a case where the distance to the free spot is not the optimum one available. As discussed in [7], an effective parking placement strategy makes the better use of parking spot resources possible. In this paper, we present a hierarchical placement approach with binary search tree(BST) based on nearest location. First, the nearest parking area is located. Once the optimum distance car park is found, it is used for the second stage of search to locate the available parking spot This hierarchical method with BST significantly improves the search process in terms of required search time and energy efficiency. Time is the most valuable metric in our project. By using a hierarchy in placement algorithm, we consume less time while finding nearest empty spot in car park. Saving time while parking a car means that we save energy, fuel, even less CO2 emission. As a summary, main objective of this project is saving time using hierarchical approach with BST in placement algorithm. The rest of this paper is organized as follows. Related works in the literature are discussed in Section 2. Section 3 presents and explains the proposed approach. In Section 4, simulation results are discussed and a comparison between the new approach and the non-hierarchical approach is performed. Section 5 concludes the study and gives recommendations about future directions.

Section snippets

Related works

It is possible to categorize the existing studies for smart parking applications as open and close area types. When existing studies are investigated, it can be seen that most of the solutions in the literature mainly focus on close area parking spaces [15]. It is easier to control close areas in terms of availability of parking spots by using sensors in entrance and exit points. In addition, the fragile nature of wireless sensors makes open area applications more challenging. Maintenance and

Hierarchical approach

In this section, the hierarchical placement approach is presented and explained. This approach includes two levels of hierarchy as shown in Fig. 1, to make placement process more efficient. First level is the identification of suitable car park. In the first level, algorithm only checks nearest car park. For example, the car park in our university Middle East Technical University Northern Cyprus Campus (METU NCC) has seven car parks which are culture convention center car park, academic

Simulation and results

In simulation, same scenarios are used to evaluate non-hierarchical, hierarchical and hierarchical with BST approaches. In addition, same uniformly and exponentially distributed car parks and parking spots are used. The only difference is how we store car parks and parking spots. In non-hierarchical one, they are stored as linked lists and there is no hierarchy. In hierarchical one data structure is again same, but the hierarchy is applied. In the hierarchical with BST approach, binary search

Conclusion and future work

The concept of IoT is rapidly becoming more and more popular with variety of application areas. IoT concept is going to become an important part of our daily life, and work life. It can be employed efficiently to create more comfortable environment and living spaces. On the other hand, our planet needs some green solutions because energy efficiency is a very important concept nowadays as we are running out of energy resources. This paper introduces an energy and time efficient approach which

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