This editorial introduces the special issue entitled “Applications of Internet of Things”, of ISPRS International Journal of Geo-Information. Topics covered in this issue include three main parts: (I) intelligent transportation systems (ITS), (II) location-based services (LBS), and (III) sensing techniques and applications. Three papers on ITS are as follows: (1) “Vehicle positioning and speed estimation based on cellular network signals for urban roads,” by Lai and Kuo; (2) “A method for traffic congestion clustering judgment based on grey relational analysis,” by Zhang et al.; and (3) “Smartphone-based pedestrian’s avoidance behavior recognition towards opportunistic road anomaly detection,” by Ishikawa and Fujinami. Three papers on LBS are as follows: (1) “A high-efficiency method of mobile positioning based on commercial vehicle operation data,” by Chen et al.; (2) “Efficient location privacy-preserving k-anonymity method based on the credible chain,” by Wang et al.; and (3) “Proximity-based asynchronous messaging platform for location-based Internet of things service,” by gon Jo et al. Two papers on sensing techniques and applications are as follows: (1) “Detection of electronic anklet wearers’ groupings throughout telematics monitoring,” by Machado et al.; and (2) “Camera coverage estimation based on multistage grid subdivision,” by Wang et al.

https://www.mdpi.com/2220-9964/7/9/334/pdf

Applications of Internet of Things

Vehicular Ad Hoc Network (VANET) has become an indispensable part of the Intelligent Transport System (ITS). Due to the mobility of the vehicular node, a serious challenge to the reliable transmission of video images and other high-bandwidth data traffic for automatic driving in VANET is presented. Multi-Radio Multi-Channel (MRMC) allows nodes to communicate on different channels simultaneously when the wireless channels are available for use, can greatly improving mobile communication stability, and provides more efficient network performance. The congestion control strategy in traditional TCP is unfit in the dynamic MRMC VANET environment under full duplex communication mode where the topology changes frequently. As a result, it is essential to draw up an optimal congestion control strategy appropriate for MRMC VANET. This paper presents a data packet accumulation model for expressing network congestion. then The MRMC VANET is endowed with a veracious physical model of particle diffusion and the optimal vehicular node data transfer rate is calculated utilizing the Fokker-Planck equation. After that an improved congestion control strategy based on TCP for MRMC VANET is proposed according to the above results. In the last part we demonstrate the superior performance of the proposed congestion control strategy in MRMC VANET through NS2 simulation.

An Improved Congestion Control Strategy Based on TCP in Multi-Radio Multi-Channel VANET

Mobile multimedia applications have recently attracted numerous interests in mobile ad hoc networks (MANETs) supporting quality-of-service (QoS) communications. In TDMA-based MANETs, time slot assignment is essential to provide the enough bandwidth to meet the traffic flow demand and support collision-free QoS flow transmission. In this paper, we propose an on-demand QoS routing protocol to support TDMA-based bandwidth reservation (QoS-TDMA). Basing on the proposed network model, a distributed time slot assignment scheme, time slot reuse scheme and routing discovery protocol are presented to support multimedia communication and to satisfy QoS bandwidth requirement. The proposed time slot assignment scheme can enhance slot reuse rate and remain more free slots for the whole network. Simulation results show that the proposed scheme can improve effect of the slot assignment, increase throughput of networks, and reduce packet loss ratio and delay.

An On-Demand QoS Routing Protocol with TDMA-based Bandwidth Reservation in Mobile Ad Hoc Networks

In this paper we face the buffer dimensioning issue in which it is required to estimate the minimum buffer size of the packet/speech multiplexer needed to meet various traffic conditions with a specified quality-of-service (QoS) objectives and fixed source statistics. An important QoS measure that we study in this paper is the loss probability. The approach, based on the fluid flow analytical model, whose input consists of the superposition of homogeneous ON/OFF sources, is often used in literature for modelling packet/speech multiplexer: We also use this model. However, unlike the traditional fluid-flow approach based upon spectral expansion solution, we use matrix-analytic methods which give us closed-form exact equation to calculate the overflow probability. Further, by analyzing in asymptotic regime, we get an approximate equation from which, with simple algebraic manipulations, we get an equation for the minimum buffer size estimation.

Buffer Dimensioning for a Packet/Speech Multiplexer: A New Asymptotic Approach

Because vehicles run in high speed environments, it is difficult to establish the topology of the network. Moreover, data transmission may be interrupted by the handoff of various APs. This study established the network of roadside-to-vehicle (R2V) environment, and used the DSRC (dedicated short range communication) to achieve seamless handoff control on a streaming service. To achieve this goal, this study first used the GPS (global positioning system) to collect vehicular information (e.g., speed, direction, and location), and subsequently exchanged the parameter of vehicular information at both ends by DSRC. Therefore, the computer in the vehicle can predict the link expiration time (LET) between two mobile nodes. Furthermore, this study used two cases of handoff in vehicular networks. One case was non-overlapping handoff, and the other case was overlapping handoff. A simple formula was designed to calculate vehicular total buffer size in these two cases, and to adjust the data flow to the receiver. Finally, this study used the network simulator to simulate the actual situation of vehicular motion and network transmission. This study proved the accuracy and feasibility of mechanism through the simulation result. This study achieved the streaming of seamless handoff control in the network of R2V.

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Tai-Yang Wu

Papers

Design of Seamless Handoff Control Based on Vehicular Streaming Communications