IEEE Communications Magazine • November 201150 0163-6804/11/$25.00 © 2011 IEEE

INTRODUCTION

During the last decade, several research effortshave investigated emergent Internet of Things(IoT) application scenarios, where heteroge-neous devices, spanning from smartphones andwireless sensors up to network-enabled physicalobjects (e.g., radio frequency identification —RFID, smart visual tags), can seamlessly interop-erate in globally integrated communications plat-forms [1]. Along the same line, with the maingoal of enabling direct communications withelectronic devices via existing mobile operatornetwork infrastructures (e.g., Third GenerationPartnership Project’s Evolved Packet System —

3GPP’s EPS) in the IoT, machine-to-machine(M2M) technology has recently emerged as apromising enabler for the development of newsolutions in a plethora of IoT applicationdomains, including transportation, healthcare,ambient assisted living, smart energy, smart utili-ty metering, supply and provisioning, cityautomation, intelligent tracking, manufacturing,and so forth [2].

Because of the growing demand for M2M-based services, various standardization bodies,such as 3GPP, the Open Mobile Alliance(OMA), IEEE, and European Telecommunica-tions Standards Institute (ETSI), have recentlypromoted various standardization activities onM2M [3]. In brief, M2M enables highly scalabledirect communications among wireless enabledheterogeneous terminals, called M2M devices,and between M2M devices and central applica-tion servers, called M2M servers [4]. The ulti-mate goal of these standardization activities is toleverage widespread integration of M2M deviceswith any existing service-level solution. However,addressing integration in IoT applicationdomains is a very challenging issue, and, to thebest of our knowledge, despite the great interestand relevant research efforts, no commonlyagreed solution has been identified so far. Nev-ertheless, it seems natural to follow middleware-level approaches to address M2M integrationissues, and to simplify the development and sup-port of emergent M2M applications [5].

Several research efforts to address the aboveissue are still underway. However, available solu-tions are still proof of concept prototypes andcannot easily be adopted in production environ-ments. These considerations therefore raise sev-eral challenging research questions. How can weintegrate emerging M2M solutions in availableplatforms? Can we rely on standards andwidespread solutions to leverage M2M servicesand applications? Can we use mature produc-tion-level software components to actually imple-ment M2M applications?

ABSTRACT

Machine-to-machine communications aregaining tremendous interest from mobile net-work operators, equipment vendors, device man-ufacturers, as well as research andstandardization bodies. Indeed, M2M is a promis-ing technology for the development of Internetof Things communications platforms, with highpotential to enable a wide range of applicationsin different domains. However, providing suitableanswers to the issues stemming from IoT plat-form design requires middleware-level solutionsto enable seamless interoperability betweenM2M-based applications and existing Internet-based services. To the best of our knowledge,available proposals in the field are still immatureand tend to be proof of concept prototypes thataddress specific issues stemming from IoTdomains. This article starts from a different per-spective and aims at investigating the possibilityof implementing M2M solutions on top of cur-rently available, mature, production-level solu-tions. In this vein, we here present and discussthe design and implementation of an M2M appli-cation in the field of road traffic managementthat integrates, for the sake of efficiency, with abroad IMS-based service infrastructure.

THE INTERNET OF THINGS

Luca Foschini, DEIS – University of Bologna

Tarik Taleb, NEC Laboratories

Antonio Corradi, DEIS – University of Bologna

Dario Bottazzi, Laboratori Guglielmo Marconi

M2M-Based Metropolitan Platform forIMS-Enabled Road Traffic Management in IoT

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IEEE Communications Magazine • November 2011 51

1 Bologna metropolitantransportation web site,retractable bollard systemweb page:http://www.comune.bologna.it/trasporti/servizi/2:3023/4263/Consortium:http://www.pc104.org/

The article addresses the above issues andbuilds on practical experiences we had in thedesign of an M2M application for metropolitantraffic management that serves the needs of theMunicipality of Bologna, Italy. In particular, wehere discuss the adoption of the IP MultimediaSystem (IMS) to M2M realms. For the sake ofdescription simplicity, we focus on the descriptionof development and integration of a retractablebollard management solution1 that permitsrestricting vehicular access to protected areas.

In our solution, the adoption of IMS wasdriven by various considerations. First of all, theMunicipality plans the adoption of IMS to sup-port different services, such as video surveil-lance, traffic condition management, automaticdetection and sanction of cars that do not stopwhen the traffic light is red, and so forth. As aconsequence, IMS seemed a natural solution tosimplify the integration of M2M applications ina wider municipal service ecosystem. In addition,on one hand, IMS is an excellent integrationframework that permits to take full advantage oflegacy solutions, thus preserving past invest-ments; and on the other hand, IMS makes itpossible to effectively interact with internalM2M mechanisms and coordinate M2M devicecommunications to encompass relevant aspectsof communication management, such as conges-tion and overload control [2]. Finally, in ourdeployment scenario the adoption of IMS makesit possible to simplify the service managementprocess, as involved technical staff requires onlylimited training to administer and maintain anew IMS-based system.

The article is organized as follows. We dis-cuss the state of the art in the field and providebackground information on M2M, IMS, andintegration management in IoT deployment set-tings. We present the retractable bollard man-agement case study, wherein we provide relevantinsights on system architecture and implementa-tion. Concluding remarks follow.

BACKGROUND ANDSTATE OF THE ART

This section first briefly introduces some neededbackground material about M2M and IMS. Itthen reports about some approaches that aim tocover the challenging and still open integrationissues in IoT field.

BACKGROUND ON M2M AND IMSCurrently, there are several different ongoingM2M-related standardization activities. This sec-tion describes mainly the standardization activi-ties of 3GPP. Let us introduce a few core nodesof the 3GPP EPS network that realize basicfunctions used by both M2M (mainly) and IMS[4]. Evolved Node B is the mobile network basestation (eNB, or base station, BS, in 3G). Thehome subscriber server (HSS) is the databasestoring authentication data and profiles forclients, ranging from M2M devices to IMS-enabled clients. The serving gateway (S-GW, orserving general packet radio service, GPRS, sup-port node — SGSN —in 3G) acts as a localmobility anchor node. Finally, the packet data

network gateway (PDN-GW, or gateway GPRSsupport node, GGSN, in 3G) interfaces themobile operator network with the different pack-et data networks (e.g., the Internet).

M2M standards define a reference architec-ture and communication protocols to enableinteractions between M2M devices and M2Mservers [3, 4]. Typically, M2M devices eithertransmit or receive a predefined amount of dataat a specific frequency; for instance, a pollutionmeter sending measurement results every day at8:00 a.m. Within the framework of 3GPP, avail-able standardization proposals suggest that eachM2M device should contain a SIM card toauthenticate with a mobile network [4]. AnM2M device (called machine type communica-tion [MTC] device in 3GPP terminology) cansupport different M2M features (e.g., time con-trolled transmission, low mobility, and infre-quent transmission) to optimize the networkusage by M2M applications: these features areenabled by M2M subscriptions stored in theHSS. In order to limit communications andavoid (possible) congestion situations over thecellular mobile network, a core M2M standarddesign guideline is that M2M devices shouldoperate offline most of the time and connect tothe mobile network only when needed.

IMS sits atop EPS core nodes to realize appli-cation-level session control through the followingmain functional entities [4, 6]. The IMS client isthe session control endpoint, and participates insession setup and management via Session Initia-tion Protocol (SIP) extensions specified by theInternet Engineering Task Force (IETF) and3GPP IMS-related standards; HSS stores HTTP-like URIs (e.g., sip:user@domain) to identify anyIMS client. The application server (AS) allowsthe introduction of new IMS-based services. Forinstance, IMS enables M2M servers to be real-ized as specific ASs, and M2M devices hosting anIMS client can be controlled by and participatein IMS dialogs. Proxy-/interrogating-/serving-callsession control functions (P-/I-/S-CSCF) are thecore entities of IMS. They realize several mainfunctions, including localization, routing out/ingo-ing SIP messages, associating an IMS client withits S-CSCF (as indicated within the client pro-file), and modifying the routing of specific typesof SIP messages to ASs depending on filters/trig-gers specified by client profiles (IMS filter crite-ria) maintained by the HSS. 3GPP has alsostandardized some common IMS services such asthe Presence Service (PS) that, following a pub-lish/subscribe model, allows users andhardware/software components to publish data tointerested entities previously subscribed to theIMS PS server, defined as presentities and watch-ers, respectively. Further details about M2M andIMS are available at [3, 4, 6].

RELATED WORK ON INTEGRATIONMANAGEMENT ISSUES IN THE IOT

The IoT research field works over the growingmaturity of several related technologies, such aswireless sensor networks, RFID devices, M2M,and so forth. The growing interest in this area isalso demonstrated by the recent special issue ofIEEE Wireless Communications on IoT [1].

In order to limit

communications and

avoid (possible) con-

gestion situations

over the cellular

mobile network, a

core M2M standard

design guideline is

that M2M devices

should operate

offline most of the

time and connect to

the mobile network

only when needed.

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IEEE Communications Magazine • November 201152

Despite the encouraging results obtained so far,most research works tend to mainly focus onspecific technological issues (RFID tag readingspeed, security, etc.). Only recently, a fewresearch efforts have started to tackle IoT man-agement issues rising from the full integration ofM2M devices, non-computing entities, and (traf-fic management) services [5]. In the following,for the sake of brevity, we sketch a limited selec-tion of solutions close to our envisionedapproach, starting from those addressing lowerlayer aspects, at the M2M and IMS levels, andcontinuing with applications tackling integrationissues of IoT architectures at the service level.

As evidence that M2M is becoming an impor-tant part of the communication system, someresearchers have recently started to discussM2M wireless communication overload issues [2,7]. The work in [7] presents an analytical studyaimed at modeling M2M device communicationload in metropolitan areas, such as urban Lon-don, Taipei, and Beijing, and proposes possibleoptimizations to reduce the load at the SGSN,especially for high numbers of M2M devices inidle mode. The work in [2], instead, proposesbulk M2M signal handling to reduce the numberof transmissions between eNB and the core net-work nodes (e.g., mobility management entity,MME). The research work on IMS as an enablerfor the integration of M2M devices and wirelesssensor networks (WSNs) with mobile networks isstill in its infancy. The work in [8] analyzes anIoT monitoring scenario where IMS-enabled cellphones are opportunistically exploited to harvesturban monitoring data of interest from sparseWSNs deployed in the city. iRide, instead, is anIMS application that takes real-time informationabout traffic situations from wireless sensorsinstalled directly on the road surface, processesthem at the server side, and reports them todrivers using IMS [9].

At the service level, several successful IoTindustrial and academic research initiatives areexploring traffic management solutions. Forinstance, there are already various applicationsto inform car drivers willing to park at a parkingarea2 and similar projects to monitor free park-ing lots;3,4 these projects are important anddemonstrate the growing interest in this applica-tion domain. From a technical perspective,although addressing different applicationdomains, we can consider two recent researchefforts focusing on service integration and archi-tectural issues of IoT with an approach close toours [5, 10]. The first describes lessons learnedduring the development of web-based IoT toolsand applications aimed to facilitate managementand control of personal RFID tags at the Uni-versity of Washington [10]. This work highlightsthe importance of introducing easy-to-use ad hocweb-based user interfaces to geolocalize andmanage things, and to integrate IoT with existingservices such as Twitter. The second, instead,calls for a radical change “from today’s Intranetof things” to the “future Internet of things” andindicates as core priorities the definition of anarchitectural reference model for the interoper-ability of IoT systems and mechanisms for effi-cient integration of IoT architectures into theservice layer of next-generation future Internet

networking infrastructures [5]. However, thework focuses on the management of a WSN-equipped university building, and does not con-sider the possibility to exploit already availableand deployed technologies (e.g., M2M and IMS)to fully integrate mobile operator infrastruc-tures, M2M devices, and (pre-existing) servicesin a truly unique and valuable next-generationIoT management platform as in our proposal.

RETRACTABLE BOLLARDMANAGEMENT CASE STUDY

The design of a retractable bollard managementsolution seems a straightforward technical activi-ty: all authorized citizens are provided with cre-dentials, and, before getting access to a restrictedtraffic area, are required to authenticate them-selves to the system via a simple user interface;if the provided credentials are valid, the systemretracts the bollard and permits vehicular accessto the restricted area in the city center.

However, despite the apparent simplicity, var-ious aspects complicate the development of aretractable bollard management solution. Thesystem must be integrated in a broader architec-ture that provides advanced support to variousaspects of traffic management, such as videosurveillance of streets, detection and sanction ofvarious illicit driving behaviors, and so forth. Inaddition, the set of citizens enabled to enter adefined protected area tend to frequently changewith time, and it is subject to complex regulationthat may vary according to the emerging needsof the municipality. For example, an individualcould be granted the possibility to enter an areawith restricted vehicular access only during workdays and at a specified time (e.g., to take herchildren to a school downtown). Others could begranted permission to enter in a restricted areaonly for a short time (e.g., to reach a hotel).Finally, a further problem is system dependabili-ty. In fact, traffic concentrates in specific peakhours (e.g., morning and evening) when peopleleave/return to their houses, and any fault of theservice at these times may seriously compromisethe mobility of the city center. Hence, the systemshould provide easy-to-use tools to promptlydetect possibly occurring problems, to let work-ers in the field easily locate the faulty bollardand run diagnostic processes from their mobiledevices, such as iPad tablets.

M2M technologies are particularly promisingfor addressing the issues stemming from theretractable bollard case study. The implementa-tion of the retractable bollard architecture wouldnot justify the deployment of expensive broad-band networking solutions. On the contrary, thewidespread availability of GPRS/UniveralMobile Telecommunications System (UMTS)technologies can offer viable and cost-effectivenetworking opportunities. In addition, wirelessnetworking solutions simplify large-scale outdoorsystem deployment, especially in road trafficmanagement application domains (e.g., to pro-vide suitable networking support to traffic tollsand traffic information screens). In this scenario,each retractable bollard can be equipped with anM2M device in charge of coordinating with acentral M2M server to obtain the list of creden-

2 WorldSensing SmartCities, automated detec-tion of cars in parkingspots: http://www.world-sensing.com/smart-cities

3 University of Guelph,smart parking lot project:http://www.uoguelph.ca/~qmahmoud/fyp/nidal-nasser-3.pdf

4 Meshnetics, ZigBeeparking automation:http://www.meshnetics.com/ZigBee_Parking_Automation_Case_Study.pdf

The design of a

retractable bollard

management

solution seems a

straightforward

technical activity.

However, despite the

apparent simplicity,

various aspects

complicate its

development.

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IEEE Communications Magazine • November 2011 53

tials of authorized citizens who are allowed toenter the restricted area, to obtain updates tothis list, and to communicate possibly occurringfailures. In addition, the M2M device can takeadvantage of various input channels to let citi-zens provide their access credentials, and of thedownstanding hardware support to control thebollard and to verify its status of operability.Municipality mobile operators can locally checkthe bollard’s functionality for prompt recovery.

The need to seamlessly integrate the systemwith a broader service architecture suggested theadoption of IMS as the basic communicationmanagement support. IMS provides rich,widespread, and production-level support for thedevelopment of novel services easy to integratewith existing mobile operator networks, and alsowith other wireless infrastructures such as Wi-Fiif available, to further cut running costs. As aconsequence, IMS is particularly well suited torealize advanced service management platformsable to integrate different infrastructures andservice components according to specific appli-cation domain requirements.

Following our main design guidelines, wesketch our IMS-enabled M2M-based manage-

ment system in Fig. 1. It consists of three maindomains. Each retractable bollard hosts an M2Mdevice that participates to the M2M devicedomain. In the network domain, we show themost important 3GPP EPS nodes and IMS com-ponents that enable the communication betweenM2M device and M2M server via the mobileoperator network.

In the municipality application domain, theM2M server is the service integration core com-ponent: it interacts with M2M devices via IMS,provides suitable support to authorize citizens toaccess restricted areas by interacting with a cre-dential management server to obtain currentlyapplicable citizens’ credentials, and interactswith the metropolitan traffic management sys-tem. Each retractable bollard is associated with alist of citizens who have permission to access thearea it protects. This information is periodicallyupdated by the M2M server to the retractablebollard, and all valid credentials are locallystored within the M2M device to increase thereliability of the authorization process (whichcan complete locally at the bollard) and to limitthe M2M device-to-server communication over-head. During these periodic contacts, M2M

Figure 1. IMS-enabled M2M-based retractable bollard management scenario.

Internet

IMSPS

GGSN SGSN

M2M device

Municipality in-the-fieldoperator mobile device

Retractablebollard

working

Retractablebollard

(actuator)SIMM2M device

domain

IMS/M2Mprofiles HSS

BS1 BS2

IMSP-/I-/S-CSCF

Citizencredentials

Municipalityapplicationdomain

Mobileoperatornetwork

Networkdomain

Managementticket

Permission updates andsystem monitoring

M2Mserver

Metropolitan trafficmanagement

Retractable bollardmanagement

Credentialmanagement

Geospatialinformation

managementserver

Retractablebollard faultandmonitoringupdates

IMS is particularly

well suited to realize

advanced service

management

platforms able to

integrate different

infrastructures and

service components

according to specific

application domain

requirements.

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IEEE Communications Magazine • November 201154

device also updates authorized accesses andlocal management state, such as actuator fault,at the M2M server. M2M server exploits thatinformation to update the metropolitan trafficmanagement system, called INVENTO,5 a web-based geospatial information management con-sole used by municipality operators to remotelymonitor continuous operability of deployedretractable bollards and issue management tick-ets for needed in-the-field interventions via IMSPS. Via INVENTO and our IMS-enabled plat-form, M2M devices become Internet-connectedobjects directly manageable through a highlyintuitive and easy-to-use web interface.

SYSTEM ARCHITECTURE,IMPLEMENTATION, ANDEXPERIMENTAL RESULTS

This section details all the main distributed com-ponents by focusing on interaction protocols andlayered software architecture, and then presentssome implementation details and seminal experi-mental results.

DISTRIBUTED ARCHITECTUREApart from the authentication, authorization,and accounting (AAA) server that stores citizenvehicle authorization data, our distributed archi-tecture consists of three main components: theM2M server, the M2M device, and INVENTO.

The M2M server is the core integration com-ponent that glues together M2M devices withauthentication functions and high-level manage-ment applications; it realizes two main functions.On one hand, the bollard authorization compo-nent (BAC) periodically queries the AAA server(by using SQL queries, shown as dotted lines inFig. 2) to obtain the list of vehicles that can beadmitted in each limited vehicular traffic area,and updates it to M2M devices using standardIMS PS SIP-based message exchanges managedby the IMS AS component (continuous lines); inparticular, the M2M server realizes the presenti-ties for all vehicle restricted areas, while eachM2M device, acting as a watcher, subscribes onlyto the areas of interest (possibly more than one,e.g., when it serves a border region crossing dif-ferent areas). To limit the number of M2Mdevices concurrently connected to the cellularM2M infrastructure, the BAC schedules M2Mdevice publication time intervals by enclosing itwithin the IMS PS publish message sent to thegroup of devices. On the other hand, the M2Mserver subscribes as an IMS PS watcher to allM2M devices (also acting as presentities) toreceive the list of authorized citizens that theBAC promptly updates in the AAA server, andretractable bollard failure notifications that thebollard diagnosis component (BDC) filters,aggregates, and sends to INVENTO (dash-and-dotted RESTful interactions managed by theweb services, WS, communication component inFig. 2) that visualizes those events to the finalhuman operator.

To further reduce IMS PS traffic and avoidcongestion on the last hop wired-wireless M2Mcommunication link, we use different optimiza-

tion techniques including already standardizedones, such as resource lists to enable multiplesubscriptions through one only SUBSCRIBEmessage and partial notifications to reduceNOTIFY message length.

The M2M device interacts with the M2Mserver to receive citizen credential updates, andpublish authorized accesses and possible failures(via the IMS client component). Thanks to IMS-enabled M2M server scheduled communications,the M2M device is offline most of the time andconnects to the network only when indicated bythe M2M server to refresh citizen credentialsand upload authenticated accesses. Accordingly,all retractable bollard integration and manage-ment logic has been realized in such a way thatit is executed locally while the M2M device is indisconnected mode; in particular, the M2Mdevice consists of three main components. Theauthorization manager takes over user AAAactivities: users identify themselves by means ofan RFID card, and the authorization managerperiodically sends an updated list of authorizedvehicles to the M2M server. In order to avoidviolations, authorized vehicle lists are comparedagainst vehicle license plates (also stored by theAAA server) collected by video traffic controlgates that fully cover bollard-protected areas andall main city center access/exit streets; if thereceived RFID does not correspond to any ofthese plates, an infraction will be reported to thecitizen because she is likely to have passedaround her RFID. Let us briefly note that thiscontrol demonstrates the full capacity of IoTmanagement systems not only to integrate M2Mdevices (through IMS) with existing services,such as INVENTO, but also to exploit non-com-puting entities, such as vehicles traversing thecontrol gates, as application-level inputs. Anoth-er important M2M device component is thediagnostic procedure (DP), which implementsthe needed support to verify the continuousoperability of all available retractable bollards bychecking, at regular times, whether all of itscomponents operate in a correct way, and theresults of the diagnostics procedure are then for-warded to the server-side BDC; when multiplenotifications have not been received, the server-side BDC assumes that the retractable bollard isin a faulty condition. Finally, the bollard actua-tor control component (BACC) executes theretractable bollard’s work.

The last component is a web-based user inter-face that depicts the status of operability tooperators of the municipality control center byshowing all of the interesting information, suchas allocation of the faulty retractable bollard, averbose description of detected errors, and soforth. The interface is based on INVENTO, acommercial geospatial information managementframework (GIMF component in Fig. 2) devel-oped by Laboratori Guglielmo Marconi that sup-ports the development of Open GeospatialConsortium (OGC)-compliant services andapplications, and integrates multiple communi-cation channels to reach operators/workers.After an error notification, the control operatorcan issue a trouble ticket to trigger prompt sys-tem recovery by a maintenance team working inthe field. The trouble ticket event is notified by

5 INVENTO web page:http://invento.labs.it

Thanks to

IMS-enabled M2M

server scheduled

communications,

the M2M device is

offline most of the

time and connects to

the network only

when indicated by

the M2M server to

refresh citizen

credentials and

upload authenticated

accesses.

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IEEE Communications Magazine • November 2011 55

both email and IMS PS to interested mainte-nance team operators, and operators can rely ontheir mobile terminals (e.g., iPads) to access anINVENTO-based interface that permits them toeasily locate faulty retractable bollards andpromptly gain remote access to available diag-nostic information.

SYSTEM IMPLEMENTATION ANDEXPERIMENTAL RESULTS

We wrap up with a brief description of the finaldeployed management platform implementationand deployment. Each retractable bollard comeswith an M2M device developed atop a PC/1046

Linux-based PC board equipped with an RFIDreader and a SIM card (shown in Fig. 3).

The M2M server and all fixed servers, includ-ing IMS infrastructure components, instead runon powerful Linux boxes. In the near future, weare considering the possibility of moving these

fixed infrastructure components, currentlydeployed on premises, into the cloud with sever-al advantages in terms of both system elasticscalability and high reliability. For software com-ponents, we employed the OpenIMSCore, anIMS platform fully compliant with 3GPP IMSspecifications that provides all the basic compo-nents of the IMS infrastructure (P-/I-/S-CSCFsand HSS). M2M device and server IMS modulesare based on the eXosip stack, and OpenSIPS isemployed for the IMS PS server. INVENTOintegrates and implements widespread industrialstandard protocols and technologies promotedwithin the framework of OGC: it includes a webmap server (WMS) that permits users to be pro-vided with proprietary raster maps and relies onthe WMS standard to obtain maps from thirdparties (e.g., Google Maps and Bing). Finally,INVENTO enables a web-based user interface(Fig. 4) that provides active mapping features byexploiting the OpenLayers visualization support.

Figure 2. M2M-based management platform distributed architecture.

IMS/M2Mprofiles HSS

AAAserver

BAC

M2M server

IMS ASWS

Auth.man.

RFID reader SIM reader

BACC

SIM

SIP

GIMF: Geospatial information management frameworkWeb UI: Web user interfaceBAC: Bollard authorization componentIMS PS: IMS presence serverIMS P-/I-/S-CSCF: IMS proxy-/interrogating- /serving-call session control functionBN: Base nodeSGSN: Serving GPRS support node

BACC: Bollard actuator control componentWS: Web servicesBDC: Bollard diagnosis componentIMS AS: IMS application serverHSS: Home subscriber serverGGSN: Gateway GPRS support nodeDP: Diagnosis procedure

IMS client

M2M device

DP

IMSP-/I-/S-CSCF

IMSPS

Mobileoperatornetwork

Networkdomain

M2M devicedomain

GGSN SGSNBS1 BS2

WS

Internet

email

Municipality application domain

SMSWebUI

BDCGIMF

Invento

Vehiclesauth.

Managedobjs

Diameter SQL Restful over HTTP

Vehiclesauth.

6 PC/104 Embedded Con-sortium:http://www.pc104.org/

In the near future,

we are considering

the possibility to

move these fixed

infrastructure

components,

currently deployed

on premise, in the

Cloud with several

advantages in terms

of both system

elastic scalability and

high reliability.

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IEEE Communications Magazine • November 201156

We have already started collecting some semi-nal experimental results from our implementa-tion. Our current testing deployment consists of18 retractable bollards installed at core city centercrossings (the final deployment will include 146bollards). Each day, there are an average of 286accesses for each bollard. Those accesses are typi-cally concentrated during the peak rush hours asfollows: 88 accesses between 8 a.m. and 9 a.m.,when people leave their houses to go to work; 90between 1 p.m. and 2:30 p.m., when some peopleget back home for lunch and then go back towork (about 50 incoming and 40 outgoing access-es), and about 108 between 6 p.m. and 7 p.m.,when people return home after work.7 In theworst case situation in the evening, our systemhas to process (108 × 18)/60 = 32.4 authorizedaccess updates/min, about 1 update every 2 s.

That frequency is already high for M2M. Infact, given the small dimensions of the Bolognacity center, most of the M2M devices attach tothe same BS node; in addition, we are usingM2M communications where, for example, thedefault value for the average time periodbetween M2M device location updates is 56min [2]. Thanks to our IMS-enabled communi-cations controlled by the M2M server, we areable to evenly schedule M2M device transmis-sions to have a maximum of about 4updates/min. Let us note that we could havealso used the time controlled transmission fea-ture available at the lower M2M level, but itwould have required continuously updatingM2M device subscriptions at the HSS, whileour IMS-operated communication scheduling ismuch more flexible and can promptly adapt toload changes. The cost is as low as publishingan IMS PS message of about 500 bytes to coor-dinate M2M devices.

To conclude, this article stresses the centralrole of highly integrated organizational processesin applied research in the IoT field, especially inmetropolitan traffic management. In fact, ourwork demonstrates that following the core sys-

tem integration design guideline, from both thetechnical and organizational process viewpoints,permits already available service and IoT tech-nology assets to be exploited to quickly(re)design novel IoT services and applications asrequirements and/or municipal laws change.

CONCLUSIONSIn the years to come, IoT-based services andapplications are likely to become an integral partof our everyday life. Basic technologies thatleverage seamless interaction between unconven-tional artifacts (i.e., real life resources) havealready been developed and play a relevant rolein different application domains, such as logisticsand road traffic management.

The present work describes the design of anintegrated IoT retractable bollard managementsystem to rule vehicular access to restricted cityareas based on standard infrastructures and soft-ware components. The article also discusses themain design guidelines to consider in systemdevelopment. In particular, the article stressesthe necessity of integrating IoT-based serviceswithin the framework of enterprise managementsolutions, relying on standard solutions, and pro-viding suitable support to simplify system main-tenance and management.

ACKNOWLEDGMENTSWe sincerely thank the Municipality of Bolognafor the kind collaboration on this research. Thiswork was partially supported by the EU ProjectCIVITAS MIMOSA.

REFERENCES[1] A. Iera et al., Ed., Special Issue on the Internet of

Things, IEEE Wireless Commun, vol. 17, no. 6, 2010,pp. 8–9.

[2] T. Taleb and A. Kunz, “Machine Type Communicationsin 3GPP Networks: Potential, Challenges, and Solu-tions,” to appear, IEEE Commun. Mag.

[3] 3GPP, “System Improvements for Machine-Type Com-munications,” TR 23.888 V1.3.0, June 2011.

Figure 3. a) The retractable bollard deployment, controlled by an M2M device interface; b) equipped withthe RFID reader.

M2Mdevice

(a) (b)

Retractablebollard

RFIDreader

7 The number of accessesincoming and outgoing isdifferent due to the highnumber of one-way streetsin the city center and dif-ferent restriction appliedto the different trafficdirections, namely incom-ing accesses are typicallymore effectively moni-tored.

Our work demon-

strates that following

the core system inte-

gration design guide-

line, from both

technical and organi-

zational process

points of view, per-

mits to exploit

already available ser-

vice and IoT technol-

ogy assets to fast

(re-)design novel IoT

services and applica-

tions as requirements

and/or municipal

laws change.

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[4] 3GPP, “General Packet Radio Service (GPRS) enhance-ments for Evolved Universal Terrestrial Radio AccessNetwork (E-UTRAN) access,” TS 23.401, v. 10.4.0, June2011.

[5] M. Zorzi et al., “From Today’s INTRAnet of Things to AFuture INTERnet of Things: A Wireless- and Mobility-Related View,” IEEE Wireless Commun, vol. 17, no. 6,2010, pp. 44–51.

[6] 3GPP, “IP Multimedia Subsystem (IMS); Stage 2,” TR23.228 v. 11.1.0, Jun. 2011.

[7] S.-T. Sheu, Y.-T. Lee, and S. Lu, “Load Analysis for MTCDevices in Idle Mode or Detached State,” Proc. IEEEInt’l. Computer Symp. ’10), 2010, pp. 424–28.

[8] P. Bellavista et al., “The Future Internet Convergence ofIMS and Ubiquitous Smart Environments: an IMS-BasedSolution for Energy Efficiency,” Elsevier J. Network andComp. Apps., Special Issue on Intelligent Algorithmsfor Data-Centric Sensor Networks, May 2011.

[9] M. Elkotob and E. Osipov, “iRide: A Cooperative Sensorand IP Multimedia Subsystem Based Architecture andApplication for ITS Road Safety,” Proc. EuropeComm’09, Springer LNCS, vol. 16, part 3, 2009, pp. 153-62.

[10] E. Welbourne et al., “Building the Internet of ThingsUsing RFID: The RFID Ecosystem Experience,” IEEE Inter-net Computing, vol. 13, no. 3, May/June 2009, pp.48–55.

BIOGRAPHIESLUCA FOSCHINI [M] (luca.foschini@unibo.it) graduated fromthe University of Bologna, Italy, where he received a Ph.D.degree in computer engineering in 2007. He is now aresearch fellow of computer engineering at the Universityof Bologna. His interests include distributed systems andsolutions for pervasive computing environments, systemand service management, context-aware session controland adaptive mobile multimedia, and mobile-agent-basedmiddleware solutions. He is a member of the Italian Associ-ation for Computing (AICA).

TARIK TALEB [SM] (tarik.taleb@neclab.eu) received his B.Edegree in information engineering with distinction, andM.Sc. and Ph.D. degrees in information sciences from GSIS,Tohoku University, Japan, in 2001, 2003, and 2005, respec-tively. He is currently working as a senior researcher and3GPP standards expert at NEC Europe Ltd. Prior to his cur-rent position, he worked as an assistant professor at theGraduate School of Information Sciences, Tohoku Universi-ty, Japan. His research interests lie in the field of architec-tural enhancements to 3GPP networks, mobile multimediastreaming, wireless networking, intervehicular communica-tions, satellite and space communications, congestion con-trol protocols, handoff and mobility management, andnetwork security. He is/was on the editorial boards of IEEEWireless Communications, IEEE Transactions on VehicularTechnology, IEEE Communications Surveys & Tutorials, anda number of Wiley journals. He is the recipient of manyawards, including the 2009 IEEE ComSoc Asia-PacificYoung Researcher award, the 2008 TELECOM System Tech-nology Award, and the 2007 Funai Foundation Science Pro-motion Award.

ANTONIO CORRADI [M] (antonio.corradi@unibo.it) graduatedfrom the University of Bologna and received an M.S. inelectrical engineering from Cornell University, Ithaca, NewYork. He is a full professor of computer engineering at theUniversity of Bologna. His research interests include dis-tributed and parallel systems and solutions, middleware forpervasive and heterogeneous computing, infrastructuresupport for context-aware multimodal services, networkmanagement, and mobile agent platforms. He is a memberof the ACM and AICA.

DARIO BOTTAZZI [M] (dario.bottazzi@labs.it) graduated fromthe University of Bologna, Italy, where he received a Ph.D.degree in computer engineering in 2004. He is now chiefresearcher at Laboratori Guglielmo Marconi SpA. Hisresearch interests include middleware for pervasive andheterogeneous computing, network and service manage-ment, and advanced platforms for context management.

Figure 4. INVENTO web-based user interface.

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