micro-location for internet of things equipped smart...

IEEE INTERNET OF THINGS JOURNAL 1

Micro-location for Internet of Things equippedSmart Buildings

Faheem Zafari, Student Member, IEEE, Ioannis Papapanagiotou, Member, IEEE,and Konstantinos Christidis, Member, IEEE

Abstract—Micro-location is the process of locating any entitywith a very high accuracy (possibly in centimeters) while ge-ofencing is the process of creating a virtual fence around a Pointof Interest (PoI). In this paper, we present an insight into variousmicro-location enabling technologies, techniques and services. Wealso discuss how they can accelerate the incorporation of Internetof Things (IoT) in smart buildings. We argue that micro-locationbased location aware solutions can play a significant role infacilitating the tenants of an IoT equipped smart building. Also,such advanced technologies will enable the smart building controlsystem through minimal actions performed by the tenants. Wealso highlight the existing and envisioned services to be providedby using micro-location enabling technologies. We describe thechallenges and propose some potential solutions such that micro-location enabling technologies and services are thoroughly inte-grated with IoT equipped smart building.

Index Terms—Geofencing, Micro-Location, Internet of Things,Systems of Interaction, Beacons.

I. INTRODUCTION

The developments in the field of Information and Commu-nication Technologies (ICT) have resulted in the widespreaduse of reliable and affordable communication services suchas the Internet. Internet of Things (IoT) is defined as theability of various things to be connected to each other throughthe Internet [1]. The number of Internet equipped devicesovertook the human population in 2011 [2]. As of 2013, therewere 9 billion interconnected devices that are poised to reach24 billion in 2020 [3]. Groupe Speciale Mobile Association(GSMA) predicts that these devices will result in a $1.3trillion revenue [4] for the mobile network operators throughdifferent services such as health, utilities, automotive andconsumer electronics. IoT is a diverse field and broadly coversMachine to Machine (M2M) communication, smart grids,smart buildings, smart cities and many more. The basic motivebehind IoT is to provide advanced residential and enterprisesolutions through the latest technologies in an energy efficientand reliable manner without jeopardizing the service andcomfort level. It is poised to highly impact the every daylife and behavior of the potential users. Due to the increasinginterest in IoT and its supposed impact on us, the US National

Faheem Zafari and Ioannis Papapanagiotou are with the department ofComputer and Information Technology, Purdue University, West Lafayette,IN, 47096 e-mail: {faheem0,[email protected]}.

Konstantinos Christidis is with IBM Emerging Technology Institute andDepartment of Electrical & Computer Engineering, NC State University,Raleigh NC, e-mail:{[email protected]}.

Copyright (c) 2012 IEEE. Personal use of this material is permitted.However, permission to use this material for any other purposes must beobtained from the IEEE by sending a request to [email protected].

Intelligence Council (NIC) has included IoT in the list of“six Disruptive Civil Technologies” [5]. NIC forecasts IoT topenetrate the everyday entities by 2025 including furnitures,home appliances, food packages and many more. The reportdiscusses the vast horizon of opportunities that can exist in thefuture. For example, integrating the popular demand with thetechnological advancements will drive a broad diffusion of theIoT that will contribute highly to the economic developmentjust like Internet right now.

IoT plays a key role in the transformation of residentialand enterprise buildings to being ’smart’. Smart buildings aimto provide solutions that are energy efficient, environmentfriendly, disaster manageable and comfortable. Therefore, anysolution that can potentially increase the comfort level andprovides the fore-mentioned services can be incorporated intosmart buildings. Indeed it is a system that allows for thebuildings to have a “brain” [6] so that they can handle thehuman and natural disasters properly, maintain the energyexpenditure (hence reducing the greenhouse gas emission)while at the same time provide the level of comfort thatthe tenant asks for. Micro-location is the process of locatingan entity with a high accuracy (in centimeters). Geofencingis a related concept that creates a virtual entity around anyPoint of Interest (PoI). Micro-location can assist in locatinga tenant within an IoT equipped smart building. The posi-tion of the user can then be utilized to provide him witheffective and efficient solutions. In this paper, we aim toprovide a thorough survey of various micro-location enablingtechnologies that can assist the IoT equipped smart buildings.We discuss various micro-location enabled services that willimprove the tenant experience. We argue that due to the hugeproliferation of smartphones with multiple-sensors, the tenant-building interaction can be optimized for an enhanced userexperience through the utilization of micro-location enablingtechnologies and provision of micro-location enabled services.We also highlight some of the challenges that micro-location iscurrently facing and propose effective solutions. In summary,our work presents the following concepts

• A thorough survey of various micro-location enablingtechnologies, micro-location enabling techniques;

• Current and envisioned micro-location enabled servicesthat can enhance the tenant’s experience;

• Various challenges of incorporating micro-location in IoTequipped smart buildings and possible general solutionsthat can address the challenges;

The paper is structured as follows: Section II provides the


Fig. 1. IoT components of a smart building.

basic description of Smart Buildings and Internet of Things.Section III presents a description of various micro-locationenabling techologies. Section IV describes the micro-locationenabling techniques. Section V presents an insight into variousmicro-location enabled services that are currently provided andenvisioned to be provided in future. Section VI highlights thecurrent challenges and some of the suggested solutions, andwe conclude this paper in section VII.

II. IOT AND SMART BUILDINGS

Both IoT and smart buildings are inter-related. Indeed smartbuildings will mostly rely on IoT for serving the tenants. Inthis section, we provide a basic description of smart buildingsand IoT. Following subsection discusses smart buildings.

A. Smart Buildings

The Institute for Building Efficiency [7] defines smart build-ings as the buildings that can provide low cost services suchas air conditioning, heating, ventilation, illumination, security,sanitation and various other services to the tenants withoutadversely affecting the environment. The basic motive behindthe construction of smart buildings is to provide the highestlevel of comfort and efficiency. For example, once a tenantenters an enterprise the temperature, humidity and the lightingare adjusted according to his personalized levels of comfort,his computer and the corresponding applications are turned on[6]. At the same time, the interconnection of the automationsystems can assist with the disaster management and provideemergency services. For example, the fire sensors can alertthe ventilation system to turn of the fans hence the smokeand the fire can be contained in a specific area. The damagesin the attack on Pentagon in 2001 were reduced thanks tothe advanced automation system (smart building) [6]. In orderto do so, there is a need for added intelligence that startsfrom the design phase until the building gets functional. Smartbuildings utilize IT for interconnection of various subsystems(usually independently operated). Such interconnection resultsin the sharing of information that optimizes the performance

of the building, allows the building to interact with the tenant,and even be connected with other adjacent smart buildings.At the same, as the IoT is integrated into the smart building,there is a need to store, process and analyze the informationobtained from the interacting entities (tenants, other buildings,sensors etc.). A smart building also has some level of energyindependence. It has to have its own power generation throughrenewable energy resources, and incorporate energy efficienttechnologies. For example, solar photovoltaic windows cancollect energy [8]. At the same time, the smart buildingis connected with the smart grid, hence the excess energycan be provided to the grid or other buildings based on therelative agreements. This may result in an extra revenue for thebuilding. Hence, the general characteristics of a smart buildingare

• Various interconnected business systems;• Equipping the tenants or people with technology;• Connection to various other buildings;• Connection to the smart grids.

Fig. 1 presents various IoT components that are part of thesmart buildings. Section V contains detailed information abouthow these IoT components can benefit from micro-locationand geofencing to enhance the performance of smart buildings.Significant amount of research has been done to improvethe architectural design of smart buildings and incorporatemore technologically advanced systems into the architecture.There are two open communication standards for building au-tomation known Building Automation and Control Networks(BACnet) and LonWorks (where Lon stands for Local Oper-ating Network). Both these systems have a different approachtowards the integration of different subsystems. BACnet beinga communication only standard is mostly concerned withelectrical and mechanical systems. LonWorks combines thecommunication part with hardware and was used in transporta-tion and utilities industry, however it is now used in buildingsas well. These two networks are not mutually exclusive andBACnet can work with some specific hardware as well. Boththe systems perform their tasks differently. While BACnet


defines different priority levels for performing the tasks such asthe priorities of signals in the event of a fire, LonWorks mightuse different channels for different signals. While these twocommunication standards have started to establish themselvesin building automation, there is still a long way to go. Suchbuilding automation systems help in reducing the operationcost [6].

Wireless Sensor Networks (WSNs) are playing a key rolein the smart building automation. The WSNs are mainlydesign for control and automation of smart buildings. Hence,the collaboration and interconnection of all these sensors isbringing the attention to the IoT. Localization has also beena fundamental area of research in WSNs. Interested readersare referred to [9], [10] for further information about posi-tioning in WSN. There are two different WSN architecturalapproaches, the IP based and non-IP based approaches [1].The Internet Protocol Version 6 (IPv6) based Low powerWireless Personal Area Network (6LoWPAN) is the IP basedsystem. IPv6 is deployed over the 6LoWPAN protocol alongwith Constrained Application Protocol (CoAP). The IEEE802.15.4 Zigbee protocol serves as the link layer and the IPv6-6LoWPAN provides the services of the network or IP layer.

The application layer services are provided by the CoAP. Inthe non IP based system, the physical and link level servicesare provided by IEEE 802.15.4, however a simpler networklayer protocol can be used called Rime. It is the inbuilt IP layerof Contiki [11] and provides addressing as well as multi-hopnetworking facilities such as unicasting and broadcasting [12].Rime cannot provide transport layer services, so a combinedtransport and application layer service is implemented via theexchange of JavaScript Object Notation (JSON) objects for thehandling of application layer messages. The IP based systemperforms better in terms of latency and energy consumptionhowever the non-IP based system outperforms the IP basedarchitecture in terms of memory footprint [1].

B. Internet of Things

The integration of sensing with embedded computing de-vices in smart buildings results in the evolution of the embed-ded Internet. Kevin Ashton coined the term Internet of Things(IoT) in 1999, however it was in the field of supply chain man-agement [13]. The term over the years has incorporated variousapplications that can range from health care, transportation andutilities. The fundamental idea for IoT is the interconnection ofvarious ”Things” such as sensors, smartphones, actuators, orphysical items tagged/embedded with sensors such as chemicalcontainers with temperature sensors. The cooperation amongthese devices forms the basic pillar upon which IoT standsand makes it possible for them to achieve the commongoals [14]. The IoT is becoming extremely popular as thecommunity looks into the possibilities from the generation ofdata from simple static IoT objects (e.g. a coffee machine)to the mobile devices which come with sensing, computingand communication capabilities. At the same time, IoT isstrongly tied to the Big Data era due to the enormous datathat the ”Things” can generate. For the interconnection ofthese devices, different wired or wireless standards exist [15].

Fig. 2. IoT: Connecting everything through the Internet

Some of the common wireless standards that are used forIoT are presented in Table I. The application and servicesprovided by the IoT can be both residential and commercialranging from e-health [27], e-marketing [28], intelligent carparking system [29], intelligent transportation system [30]–[32], automation, and logistic services. However, new servicesare nowadays deployed based on the IoT, as it is fore-seen thatby the year 2025, IoT will encompass most of the appliances,food packaging, documentations, furniture and many more [5],[33].

For a thorough integration of the IoT into the real world,there are several challenges that need to be addressed includingthe interoperability of the devices, device smartness, secu-rity, privacy, device energy consumption, device processingcapability, and network addressing [27]. Fig. 2 presents anexemplar IoT infrastructure. Various systems and devices areinterconnected through the Internet. It is evident from thefigure that various devices used in residential, transportation,enterprise, healthcare environments, and literally everythingelse in the world can be connected through the Internet. Hence,current standards and technologies have to be optimized tosupport the multitude of wireless devices [34], [35]. Hencethe long envisioned release of 128-bit IPv6 addresses [36] isbecoming a need as we move towards the IoT era. Due tothe increase in the popularity of IoT, some research initiativesare in place now. The European Commission started pushingfor IoT technologies related initiatives in 2005 [37]. NationalScience Foundation (NSF) in the US includes the IoT as partof their cyberphysical systems, where the goal is to designsystems that merge physical and computational resources .[38].However, this program also covers a wide area of applications


TABLE IKEY WIRELESS TECHNOLOGIES USED IN IOT

Technology Maximum Range Maximum Frequency Maximum ThroughputBluetooth IEEE 802.15.1 [16] upto 100m for Class A 2.4 GHz 24.0 Mbps with version 4

ZigBee IEEE 802.15.4 [17] upto 100m with certain tradeoffs 2.4 GHz 2-250.0 KbpsIEEE 802.11a [18], [19] 5000m outdoor 5 GHz 54 Mbps

IEEE 802.11b 140m outdoor 2.4 GHz 11 MbpsIEEE 802.11g 140m outdoor 2.4 GHz 54 MbpsIEEE 802.11n 250m outdoor 2.5/5 GHz 600 MbpsIEEE 802.11ac 35m indoor 5 GHz 1.3 Gbps with 3 antennas and

80 MHzIEEE 802.11ad couple of meters 60 GHz 4.6 Gbps

WiMAX [20] depends on cell 2.3 GHz, 2.5 GHz and 3.5 GHz 365 Mbps downlink/376 Mbpsuplink

Long Term Evolution [21] depends on cell 2600 MHz 300 Mbps downlink/75 Mbpsuplink

Long Term Evolution-Advanced [22] depends on cell 4.44-4.99 GHz 1 Gbps downlink/500 Mbpsuplink

Ultra Wide Band [23] 10-20m 10.6 GHz Upto 480 MbpsRadio Frequency Identification (RFID) [24] upto 200m upto 10 GHz Upto 1.67 Gbps [25]

WiFi Direct [26] upto 200m 2.4/5 GHz Upto 250 Mbps

such as smart grids, intelligent transportation, smart manufac-turing and smart health care.

IoT has huge potential and a wide range applications thatit can be applied to. As of now, only a very small amountof services are provided to the consumers [27]. The futureapplications are envisioned to enhance the life quality of thetenants at the office, home, gym, library, hospital etc. Partic-ularly smart environments such as in residential or enterprisedomain has a great potential. Solutions that can improve theindoor environment experience will open up lots of revenueearning sources as well as enhance the tenant comfort level.Using IoT in smart cities/smart buildings certainly can providereliable and efficient solutions as it will allow the user tointeract with the entities.

C. Application Layer Technologies

The basic feature of any application layer technology inthe IoT is the fact that these devices are resource-constrainedand may function in constrained IP networks. A constrainedIP network may exhibit high packet loss, small packet sizes,but needs to scale to a substantial number of devices. Thesedevices, otherwise referred as the Things, may switch severaltimes to sleep mode, and “wake up” for brief periods oftime. A resource-constrained device also has limited RAM,and processing capabilities. Constrained networks can occuras part of home and building automation, energy management,and the Internet of Things.

To this end, thera are two IETF efforts to standardizethe transactions in the IoT world. The Constrained RestfulEnvironment (CoRE) working group is defines the frameworkfor a limited class of applications, i.e. those that deal withthe manipulation of minimal resources in constrained environ-ments. This class includes the Things, whether they are sensors(e.g. temperature sensors, light switches, and power meters),or control actuators (e.g. light switches, heating controllers,and door locks).

The second effort refers to Concise Binary Object Repre-sentation (CBOR) protocol, a data format meant as a building

block for IoT protocols. CBOR messages can be serialized us-ing compact code to fairly small message sizes. Both of thesecharacteristics allow for faster transmission and processing onresourceconstrained IoT nodes. The data format is based onthe JavaScript Object Notation (JSON) data model, a plusgiven the development communitys direction towards end-to-end JavaScript for Web services. CBOR allows the encodingof binary data, and is itself encoded in binary. Finally, it isextensible through a tagging mechanism that identifies datathat warrants additional information.

Moreover, using IoT in smart buildings will require using alarge number of sensor nodes for the provisioning of variousservices. The management of such large number of sensorsis an issue itself. The network must have the capability ofefficiently self diagnosing and self healing. The integration ofvarious standards results in the Building Management Systems(BMS). Open Framework Middleware (OFM) can be used forthe management of WSN in smart buildings [39]. A rule basedfault analysis engine and structured knowledge when coupledwith the OFM will help in root cause analysis and the networkevent correlation. Such systems can be explicitly interfacedwith the BMS. Such a solution is one of its kind since themanagement of sensors to be used for IoT in smart buildingsis an uphill task and there is hardly any general purpose WSNmanagement middleware present in the literature. Softwarearchitectures can be used for asset management in smartbuildings that can facilitate the engineers in receiving andupdating the word orders and information about assets throughutilization of mobile technologies and augmented reality [40].A three layered architecture that contains different modulesconsisting of data collection, work order and asset manage-ment and event enrichment and management can help inbuilding management system (BMS). Message Queue Teleme-try Transport Protocol (MQTT) can be used for messageexchange among various system components while CommonAlert Protocol can be used to model the order of work anddifferent alerts that can be then forwarded to the augmentedreality application. The significance of such architecture is


that the system functionality can be encapsulated and theinteroperability of various subsystems is guaranteed. Also,various data standards can be integrated and the maintenance,upgrading and management of the various service requests andbuilding assets becomes easy.

III. MICRO-LOCATION ENABLING TECHNOLOGIES

In smart buildings due to the indoor nature, it is of primaryimportance to locate the user in order to enable the interactionwith the rest of the interconnected things. Furthermore, thelocation of the user can be used to provide a wide range ofnovel services. Micro-location and geofencing fall in the broadcategory of the Location Based Services (LBS).

LBSs have been widely used in outdoor environments fornavigation services in cars, airplanes etc. For example, thewidely used Global Position System (GPS) allows a userto identify their coordinates on a map with an accuracyof approximately 10m [41]. This fact, combined with thesystem’s poor performance indoors (no line of sight withthe satellites) and its high toll on battery life, render itunsuitable for use in a smart building setting [42], apart fromrough geofencing. There is an increasing interst in IoT andsmart cities/buildings as depicated in Fig. 3 [43], that canfurther increase by incorporation of micro-location and ge-ofencing based services in such IoT equipped smart buildings.Realizing the significance of micro-location and geofencingbased services and technologies in IoT equipped buildings,the number of micro-location and geofencing enabled productsare seeing a significant increase such as: For instance, in2013 Qualcomm released the Gimbal [44] that uses the recentiBeacon protocol by Apple [45]. Similarly Estimote [28] in2014 released a combination of Beacons and an SDK thatcan be used to develop micro-location applications. Severalother big companies are moving towards this direction likeGoogle [46] and Cisco [47], as the IoT is considered bymany the next ”Big Thing” in the market and equipping smartbuildings with IoT can provide much efficient solutions. Inour study, we specifically focus on the use of micro-locationand geofencing techniques in IoT equipped smart buildingswith emphasis on indoor area, in which IoT can be seen as aSystem of Interaction, which is a term recently coined by IBM[48]. Effectively, a System of Interactive Things can enhancethe performance of smart buildings and can result in efficientsolutions. Therefore, from hereon we would particularly stresson micro-location and geofencing LBS as its incorporation intoIoT in smart buildings is full of potential.

Geofencing is considered a Zone Based LBS [49]. It definesa virtual fence around a certain Point of Interest (PoI). Thisfence can take various geometric shapes, be it rectangular,circular, or polygonal. The goal of a geo-fence is to providetargeted services related to a predefined area. Fig. 4 depicts ageofence example. There are numerous examples: for examplea customer that enters a museum is notified about the properpath towards the exhibition of his interest, or an ElectricVehicle that is close to the geofence of a charging facilitycan be notified about a discount coupon. In micro-location, thegoal is to have the location of a user or object pinpointed with

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Internet of ThingsSmart CitySmart GridSensor Networks

Fig. 3. Google search trend for keywords IoT, smart cities, smart grids andsensor networks

Fig. 4. A circular geofence around a smart building that advertises electriccharging facility to an electric vehicle.

the highest degree of accuracy possible [50]. This essentiallyallows the system to place the user within a geofence withcertainty; it also gives rise to other capabilities, such asallowing the user to position themselves within a buildingand track their path. Some of the enabling technologies forgeofencing and micro-location are presented below.

A. Bluetooth Low Energy based Beacons/iBeacons

The Bluetooth Special Interest Group (SIG) proposed theBluetooth Low Energy (BLE) or Bluetooth Smart that is alsoknown as Version 4 of the Bluetooth Technology [51]. Itconsists of the following layered architecture.

• Physical Layer (PHY): The PHY layer handles the trans-mission and reception of the data.


• Link Layer (LL): It provides the medium access, flowcontrol and connection establishment related services.

• Logical Link Control and Adaptation Protocol (L2CAP):It multiplexes higher layer data and provides servicessuch as fragmenting and reassembling the large datapackets.

• Generic Attribute Protocol (GATT) and Generic AccessProfile (GAP): These are the top two layers of theBluetooth stack.

A BLE device can be either a master or a slave. A masterBLE device can simultaneous connect to various slave deviceshowever each slave is connected to a single master. In contrastto the earlier bluetooth versions, a BLE slave advertises oneither one or all three allocated advertisement channel in orderto be discovered. The Master BLE device scans the channelsperiodically to discover the slave devices. After the masterdiscovers the slaves, the data is transferred through periodicconnection events where both the master and device sleep andwake up to exchange the frames. The devices sleep for mostof the time that enhances the energy efficiency of the devices.

The energy efficiency feature of BLE has made it an attrac-tive technology for the miniscule devices known as iBeacons.The iBeacons were introduced by Apple [45] and the BLEbased iBeacon protocol is meant to assist any BLE enableddevice to detect its proximity to the iBeacon device. TheiBeacon periodically transmits a beacon that can be picked upby the BLE enabled device that subsequently allows them toposition themselves within the building. Due to the low energyconsumption of BLE, the iBeacons can be powered throughany coin cell battery which can run for years based on theconfiguration of the beacon parameters such as transmissionpower, probing frequency etc. The iBeacons can be usedfor both micro-location as well as geofencing. They can beused for both indoor and outdoor environments with indoorenvironment being the dominant one.

Apple has standardized the iBeacon advertisement format[52] and the advertising packet consists of following compo-nents.

• Universally Unique Identifier (UUID): It is the mandatory16 byte string that is used for identification of theibeacons used by a specific brand or company ’A’.

• Major value: The major value is an optional 2 byte stringthat can be used to distinguish the iBeacons of a specificbrand ’A’ that are located in different localities such as acity ’B’.

• Minor Value: Just like major value, the minor value isalso an optional 2 byte string that is used to identify thebeacon of any brand ’A’, in city ’B’ and deparment ’C’.

The iBeacons particularly perform the task of:a) Distance Measurement: In order to measure the dis-

tance from a particular beacon, the BLE enabled device usesthe Received Signal Strength Indicator (RSSI). The value ofthe RSSI is an indicator of not only the proximity of the deviceto the iBeacon but also shows the accuracy of the obtainedestimation results.

b) Ranging: The distance of the BLE enabled device andthe iBeacon can be in any of the following four ranges [53]

• Immediate: The device is very close to the iBeacon.• Near: The device will be in the ’near’ range if it is located

at a distance of about 1-3m with Line of Sight (LoS)• Far: A device estimated to be far indicates that the

confidence about the accuracy of the estimated proximityis low.

• Unknown: A device which is in the unknown range mightnot be close to the iBeacon or it can be due to the absenceof recent initiation of ranging.

Once the BLE enabled receiver picks up the beacon from theiBeacons, it sends the specific UUID to either a server or cloudwhere the particular event related to the UUID is sent backto the BLE enabled receiver and is handled accordingly. It isalso possible that due to obstructions, a device’s range mightbe falsely detected. iBeacons is an attractive technology thatcan be used for micro-location purposes. Due to the expectedimpact of the iBeacons, it has garnered significant interest fromdifferent companies. Several companies are producing beaconsand are offering beacon-based services; we list some of thesein Table III. Recently, the University of Mississippi decidedto start using Gimbal’s beacons for facilitating its sports fans[54]. The basic idea is to use the beacons to enhance the gametime experience of the fans and facilitate them with checkin to the arena and provide them with relevant informationand notifications. The beacon technology is poised to providebetter consumer experience and increase the profits of thecompanies. The ability to provide accurate micro-locationbased marketing and other services can assist the consumerand be a source of great income for companies. The mobileinfluenced retail sales are forecasted to be 689 billion U.S.dollar in the US by the year 2016, overtaking e-commerce[55]. Therefore, these technologies have a great potential andtheir incorporation into smart buildings will facilitate both theconsumer and the seller.

B. Ultra-Wideband Based Micro-location

The Ultra-wideband (UWB) based radio technology has afractional bandwidth that is greater than or equal to 20% wherefractional bandwidth is the ratio of transmission bandwidthto the band center frequency [60]. UWB has an absolutebandwidth greater than 500 MHz. There are a number ofadvantages associated with using high bandwidth that canfacilitate both communications and radars based applications.Using high bandwidth provides higher reliability because theprobability of signals going around any obstacle increases dueto the availability of wide range of signals having differentfrequencies. Also the power spectral density decreases sincethe signal power is spread over a large number of frequencies.Also there is a decrease in interference as well as interceptionprobability. For micro-location, the UWB has two differentphases [61]:

1) Ranging: The process of ranging involves estimation ofthe distance or angles between any two nodes [61]. There area number of techniques available for ranging such as Angleof Arriva (AOA), Received Signal Strength (RSS), Time ofArrival (TOA), or the hybrid of any these two. Since UWBhas a good time-domain resolutions due to wide bandwidth


TABLE IIPOSITIONING TECHNOLOGIES

Technology Accuracy TransmissionPower

Cost BatteryImpact

Feasibility forMicro-location

Beacon 0.1m 0-10 dBm [56] low low YesUWB based locationing 0.1m [57] -41.3 dBm/MHz

[56]high low Yes

Magnetic Field Mapping 0.1m-2m [58] N/A N/A N/A YesHybrid of RF and IR, or RF and Ultrasonic technologies 1m [59] N/A N/A N/A YesWLAN, 3m [59] 15-20 dBm [56] high high NoZigbee 3m [59] -25-0 dBm [56] low low No

GPS 10m outdoor [59] Very high high high No

that can provide sub-centimeter resolution ability, thereforeTOA based tecniques are used with UWB for ranging.

2) Localization: The process of ranging results in rangeestimates between the fixed device (known position) and themobile device (unknown position). The fixed device for aUWB based system is the UWB Access Point (AP) while themobile device can be any smartphone, sensor etc. The nextstep is localization i.e. estimating the location of the mobiledevice. There are a number of various methods available forestimating the position of the mobile device such as the Non-linear Least Square (NLS) estimator.

UWB technology went out of favour couple of years agodue to the complexity and various other issues, however ithas recently seen a rise in interest since UWB based micro-location can potentially provide an accuracy as high as 10cm[57].

C. Wireless Positioning Systems

Wireless Positioning Systems are used for geofencing; theyemploy cellular towers for positioning outdoors, and Wi-Fiaccess points (AP) when considered in an indoor setting [62].As is the case with UWB based micro-location, some of thetechniques based on WPS for positioning are angle of arrival(AOA), time difference of arrival (TDOA) and enhancedobserved time difference of arrival (E-OTD). Such geometricapproaches are based on the transformation of the radiofrequency (RF) signal measurements into estimated distancesand angles which are then used to deduce the location of thesignal source using triangulation and standard geometry. WiFiinfrastructure has also been used in [63] for indoor localizationpurposes without using any site survey. While site-surveycan assist the performance of WPS, the proposed system isoptimized to work efficiently even in the absence of any site-survey. The main concern associated with WPS is privacy. Thecellular towers or Wi-Fi access points (AP) are vulnerable andcan result in corruption of privacy. Attacks such as man-in-the-middle attack [64] can allow any third party to access theinformation by any user sent to an AP or cellular network. Theuser might be communicating his positioning information tothe AP that the third party can have access to hence violatingthe user privacy.

D. Magnetic Field Mapping

Modern day smart phones are equipped with the ability ofsensing and recording the variations in the earth’s magnetic

TABLE IIIBEACON BASED SERVICES

Company Service DescriptionApple Inc.[45] The iBeacons are used for micro-location

purposes. They are Bluetooth Low Energydevices that enable LBS.

Gimbal [44] Gimbal’s beacons provides a context-awareadvertising platform. The beacon’s commu-nicate through bluetooth smart and theyare as per the specifications of Apple’s i-beacon.

Onxy Beacon [65] Onxy Beacon also provides beacon basedservices that can help in better marketingand LBS. Onxy beacon also offers a beaconmanagement system that is cloud based andhelps in building micro location enabledapplications for the beacons.

Swirl using iBeacon [66] Swirl uses iBeacons and provides end-to-end mobile marketing platform within astore. It is an enterprise grade platform thathelps to create, manage and optimize theLBS based mobile marketing.

Sonic Notify [67] Sonic Notify uses beacons to provide enter-prise proximity solutions.

Estimote [28] Estimote utilizes beacons for creating newand contextually rich mobile services.

field that can be used to create an indoor location map.IndoorAtlas [68] is the pioneer in providing this innovativetechnology for finding the location of any device henceproviding us with the micro-location.

E. Radio Frequency Idenfication (RFID)

Radio Frequency Identification (RFID) is a technology thatassists in data storage and retrieval utilizing the electromag-netic transmission to some integrated circuit that is compatiblewith radio frequency [69]. The entire RFID system consistsof a number of basic components such as RFID readers, tagsand their intercommunication. The RFID reader is responsiblefor reading the data emitted by the tags. RFID systems usesspecific frequency as well as protocols that govern the trans-mission and reception of data. The RFID tags are categorizedinto

• Active RFIDs: They are equipped with a battery as wellas radio transceivers which enhances their range.

• Passive RFIDs: They operate without any battery andreflect the RF signal which is transmitted by the reader.The information is added through modulation of thereflected signal. They are meant to replace the traditional


bar codes and are lighter and cheaper than their activecounterparts.

Despite their limited range, then can be used for positioningpurposes and can be a viable option for positioning purposesenvironment when used in triangulation with Wi-Fi and NearField Communication (NFC) [70]. Since most of the usersrely on smart phones, the problem with RFID is that most ofthe devices right now do not have RFID chips or tags. It canbe used for micro-location purposes and can provide accuracyas high 20-30cm [24]. There are other technologies in themarket that can provide positioning services such as infraredand ultrasound. Google [71], AlterGeo [72], Skyhook Wireless[73], Navizon [74], Infosoft [75], and Combain [76] are someof the most well-known providers of positioning services.Table II presents a summary of the discussed technologiesthat can provide LBS for IoT in smart buildings.

IV. MICRO-LOCATION ENABLING TECHNIQUES

In the previous section, we covered the major technologiesused for indoor localization. This section focuses on the formsof location (i.e, physical, symbolic, absolute and relative.The physical location is measured in 2D/D coordinates (e.g.degree/minutes/seconds). Symbolic location is natural expres-sion of the location in a smart building for example, office,elevator etc. The absolute location is based on a referencegrid for all located objects. The Relative location determinesthe proximity to a known object. Each of these techniques isindependent of the technology that is used and the

A. Triangulation

Triangulation is the technique that involves using threedimensions to estimate the location of the target. There aretwo different derivations of triangulation [77]

• Lateration: The object’s position is estimated through themeasurement of the distance between the object and var-ious reference points. It is also called range measurementtechnique.

• Angulation: Relies on the computation of angles relativeto a number of reference points for estimating the positionof any entity.

Rather than measuring the distance directly through ReceivedSignal Strength (RSS), the Time of Arrival (TOA), or TimeDifference of Arrival (TDOA) while the distance is obtainedthrough either the computation of emitted signal strengthattenuation or multiplication of travel time and radio signalvelocity.

1) Lateration Techniques:a) Time of Arrival:: In TOA the distance between the

reference unit and target (either stationary or mobile) isproportional to the time of propagation. In order to locateany target in a 2D environment, there is need for TOAmeasurements with respect to the signals that are emitted byat least three reference nodes. Fig. 5 shows how an object’sposition can be found out using three different reference pointsin a 2D scenario.In TOA based systems, the propagationtime (one way) is determined, and is then used to obtain the

distance between the measuring unit and the signal transmitter.The problem associated with TOA is the need for precisesynchronization between the systems transceivers [77]. Alsothere is a need for a time stamp that has to be attachedto the transmitted signal so that the receiver can verify thatthe signal traveled directly, i.e. without being affected orreflected by any obstacle. A number of techniques such asDirect Sequence Spread Spectrum (DSSS) are used for TOAmeasurements. There are number of methods to determinethe position of the target. A simple method is to use thegeometric method for computing the intersection points ofthe TOA circles. An alternative method is using the leastsqures algorithm [78], [79] that calculates the position ofany entity through the minimization of the sum of squaresof the non linear cost function [77]. The assumption forsuch technique is that the target entity located at (x0, y0)transmits a signal at time instant t0 so the K fixed stationspositioned at (x1, y1), (x2, y2), (x3, y3), ....., (xK , yK) receivethat particular signal emitted by the target at time instancest1, t2, t3, ......, tK . The cost function is formulated as

C(x) =

K∑j=1

βj2cj(x)

2 (1)

The βj depends on the signal reliability received at unit j whilecj(x) can be calculated as

cj(x) = v(tj − 1)−√

(xj − x)2 + (yj − y)2 (2)

v is the speed of light and x = (x, y, t)T . The function canbe formed for any measuring unit j = 1, 2....,K and cj(x)can be zero using specific values of x, y and t. The estimatedlocation can be obtained through the minimization of C(x).

b) Time Difference of Arrival: The concept behind usingTDOA is to determine the relative position of any mobiledevice through the examination of time difference at whicha specific signal arrived at various measuring units. Thedifference between TOA and TDOA is that the latter relieson time difference rather than the absolute arrival time. Forevery single measurement of TDOA, the transmitter must belying on the hyperboloid with a constant difference in rangebetween two units of measuring. The hyperboloid equation is

Rj,k =√

(xj − x)2 + (yj − y)2 + (zj − z)2

−√(xk − x)2 + (yk − y)2 + (zk − z)2 (3)

The (xj , yj , zj) and (xk, yk, zk) are used to represent thestationary receivers j, k and x, y, z represent the target’scoordinates. An easier method to solve 3 is to use Taylor-series expansion and formulate an iterative algorithm. Non-linear regression can also provide the exact solutions to 3.Correlation techniques can also be used for computing theTDOA estimate [77]. Fig. 6 shows how the location of targetin 2D environment is estimated through the intersection oftwo or more TDOA measurements. The TDOA measurementat the points (X,Y, Z) form two different hyperbolas that canbe used to locate the target W.


Fig. 5. TOA/RTOF based localization of object.

Fig. 6. TDOA based localization of object.

c) Received Signal Strength (RSS) Based: Both TDOAand TOA are affected by multipath effect since both of themrely on the time of arrival of a signal and the arrival time of asignal is itself affected by multipath effect [77]. Therefore theaccuracy of the estimated position is not always great in anindoor environment. So the alternative method that is used isto estimate the mobile unit distance from a set of measuringunits utilizing the emitted signal strength attenuation. Suchmethods are aimed at calculating the signal path loss due topropagation. There are a number of empirical and theoreticalmodels that can be utilized for interpreting the differencebetween the transmitted and received signal strength into theestimate of range. This is shown in Fig. 7.

The path-loss models might not hold true due to thepresence of extreme shadowing and multi-path fading whichis the characteristic of indoor environments. The parametersof the path-loss model are site specific and the accuracyof the obtained results can be enhanced using pre-measuredvalues of the RSS contours that are centered at the receiver.An alternative method to improve the accuracy is throughmultiple measurements at a number of base stations. Fuzzylogic algorithm can also improve the accuracy of RSS basedlocation estimation [80].

d) Round Trip Of Flight (RTOF): RTOF method relies onthe measurement of round trip time of flight of any particularsignal that is traveling from the transmitter to the measuringunit [77]. Fig. 5 shows the concept of RTOF which is alsothe figure for TOA. The difference between TOA and RTOFis also that the clock synchronization requirement for RTOFis not a stringent as it is for TOA. The mechanism of rangemeasurement in both TOA and RTOF is the same. For boththe systems, a common radar can be the measuring unit whilethe target replies back to the radar signal. The complete round

Fig. 7. RSS based localization of object. PL1, PL2andPL3 are the pathloss.

Fig. 8. AOA based localization of an entity at point W.

trip time is measured at the measuring unit. Measuring unit isagain affected by the problem of knowing the exact amountof delay or processing time that is caused by the target. Thedelay can be ignored if it is comparatively smaller than thtransmission time in a long or medium range system, butshort range systems cannot ignore it. For short range systems,modulation reflection can be a viable concept [81]. It is worthmentioning that the positioning algorithms that are used forTOA can also be used for RTOF.

2) Angulation Technique: In angulation technique such asAngle of Arrival (AoA) which is also known as direction find-ing the object’s position is determined through the intersectionof a number of pairs of angle direction lines that is formedby a circular radius of a base station to the moving target[77]. Fig. 8 shows a sketch of how angulation technique canwork. For estimating the location of any entity in 2D, themethod requires at least two known reference points and twoangles i.e (X,Y ) and θ1, θ2 respectively. The user’s locationcan be estimated using AOA either through the use of arrayof antennas or directional antennas.

The advantage of AOA over other techniques is that wecan use AOA to estimate the position of any entity in 3Dusing a minimum of three measuring units. Furthermore, AOAdoes not require any time synchronization among the units ofmeasuring. The disadvantage of using AOA is that it requirescomplex and large hardware and the accuracy of the estimation


degrades significantly when the entity moves away from themeasuring units. In order to obtain an accurate estimate of thelocation of the entity, the angles must be measured accurately,however this might be impeded by the presence of multipathand shadowing in indoor environments.

B. Proximity

The proximity based algorithms aim to provide informationabout the symbolic relative position [77]. Such algorithms relyon using a dense grid of antennas where the position of everyantenna is known. When any antenna detects a target, thetarget is thought to be co-located with it. However when morethan one antennas detects the target, then it is assumed to beco-located with the antenna with the highest signal strength.Compared to other methods, the proximity based methods areeasy to implement and its implementation is possible over arange of various physical mediums. Systems that are based onRFID and IR usually rely on proximity based methods.

V. MICRO-LOCATION ENABLED SERVICES

IoT in smart buildings utilizes micro-location enabled ser-vices for various residential and enterprise solutions, in orderto increase the tenants’ comfort and satisfaction level. Aninability to integrate such micro-location enabled servicesreduces the overall system efficiency and impedes innovation[82]. Several current uses of geofences and micro-location areshown in Table IV. We list some developing and envisionedscenarios below:

A. Targeted E-marketing

Geofencing and micro-location can play a great role in e-marketing. Already, there are some companies in the marketthat offer targeted advertising facilities that can be an addedsource of income. A hardware shop owner can create a specificgeofence around his shop that will send coupons, offers, anddeals of the day to targeted customers who enter the geofence.Since context-awareness is accompanied with the geofenceand micro-location, it can help in proper advertisement andattracting the customers to the shop. Different micro-locationenabling technologies can be used for the targeted e-marketinghowever as of now the BLE enabled beacons are emerging as aviable option. The beacon based context aware platforms is themain pillar of the targeted e-marketing and they can certainlyprovide numerous efficient solutions. There are numerousexamples of the services that can be provided through thesebeacon based context aware platforms [44] such as

• A customer in the geofence of any retail store is notifiedabout the special discounts.

• A customer notified about the availability of his pre-scription when he enters the geofence of a pharmacy. Itis timely personalized service provided to the customerthrough LBS.

• A sports fan welcomed and given information aboutspecial discounts once he enters into a sports arena.

• Updating commuters pro-actively when traveling frompoint X to Y [86].

• A customer provided with information about a shirt thatmight match the shoes he just bought.

Context awareness is one of the basic requirements of targetede-marketing since the system must know about the preferenceof a particular customer. In the absence of such information,the system might flooding advertisements to the customersthat can lead to customer irritation. The customers can thenunsubscribe to the service. As mentioned earlier, the BLEbased beacons’ fundamental use as of now is targeted e-marketing and different companies [28], [44], [66] can providesuch service. Although, companies have already started someof the services, they are still in infancy and there is a lot ofroom for improvement. The services can be further improvedand can incorporate various novel concepts as well. Theuse of geofencing and micro-locaiton will also enhance theenterprise solutions (see Fig. 1) that the IoT can provide insmart buildings. Using the positioing information for meetingmanagement systems is one such possible application.

B. Tenant Assistance

The whole idea behind IoT and smart buildings is the facil-itation of the tenant and provision of comfort and assistanceto the tenants. Tenant/user assistance is a general term and cancover a wide area of services. An art fan who enters a museumand is looking for his favorite art collection can be facilitatedby the smart buildings, utilizing the system of interaction[48] for communicating context aware location informationobtained through micro-location and geofencing technologies.Due to the context awareness, the smart building will knowthat the user is looking for a specific piece of art. So theinterconnectivity of various systems will help the building findthe user’s favorite art collection and can then provide him/herwith the directions to reach the designated area. Furthermorethe user can leave digital comments attached to the the artifactthat other users in the vicinity can browse. The user willalso be facilitated in “liking” or tweeting due to contextualawareness. The content can be bookmarked for later use. Suchgeofencing and micro-location based services can also helpenhance the museum experience through interactive guides,and contextual interpretation. It is worth mentioning here thatgeofencing detected the entrance of the user into the build-ing, micro-location found out his exact location, the contextawareness helped in finding out about the user’s preferred artcollection while system of interaction helped in interaction ofthe tenant with the building by conveying obtained informationand facilitating the user. All these systems working in syncwith numerous other systems then facilitated the user to reachthe spot. This is a classic example of how an IoT equippedsmart buildings can benefit from context aware micro-locationenabled services.

In another scenario, geofencing and micro-location canfacilitate a manager with efficient service provisions. As soonas the manager enters into the geofence of the company, hisoffice computer and the HVAC will be turned on and theoffice temperature will be adjusted as per his choice usingcontext awareness. A patient who needs emergency medicalcare can be facilitated by providing him with proper treatment


TABLE IVEXISTING GEOFENCING AND MICRO-LOCATION BASED SERVICES.

Services Description TechnologiesFleet Management [50] It involves managing the transportation fleets e.g. planes, cars, vans,

ships, rail cars and trucks.GPS, Zigbee.

Freight Management [50] It involves managing the carriers belonging to a third party for ensuringthe reliable, quick and cost effective delivery of various shipments thatcan involve integration of a range of services.

GPS (outdoor), UWB,Beacons, Magnetic FieldMapping, WLAN, Zigbeeand Hybrid of RF andIR, or RF and UltrasonicTechnologies (indoor).

Mobile Tourism [83] This service can assist tourists during their tour. Various context aware,LBS based guidance and notifications can be provided.

GPS, Zigbee.

Area Sensitive Gaming Enable-ment [84]

This service enables gaming without a specific area UWB, WLAN, Zigbee,Beacons, Magnetic FieldMapping.

Device Location and Route Ad-herence [85]

It helps in locating a device and making sure the device stays withina specific location.

Beacons, GPS, WLAN,Zigbee, Magnetic fieldmapping, Hybrid ofRF and IR, or RF andUltrasonic Technologies.

E-marketing Using geofencing and micro location, the user can be provided withlocation based advertisement. It is relatively new application and isconsidered to be the major application in the envisioned future smartbuildings.

Beacons,UWB, Hybrid ofRF and IR, or RF and Ul-trasonic technologies, andMagnetic Field Mapping.

using context awareness as well as location information forproviding him immediate medical aid. Similarly, geofencingand micro-location can be used in huge retail stores for guidinga consumer to reach a specific lane and get special discountson his/her entity of interest. San Francisco airport is testingthe beacon based micro-location system to assist the visuallyimpaired travelers [86]. The project is visioned to be extendedto help everyone at the airport in the future, providing themwith information about everything around them. In short, therange of facilities that can be provided are unlimited and itis only a matter of time until these services are provided.The use of such micro-location services for IoT in smartbuildings is certainly increasing the comfort level of the tenantand providing brand new areas of services that will resultin a better standard of life. Provision of better security i.e.both cyber and physical, efficient building automation systems,and optimum utilization of smart appliances (see Fig. 1) iscertainly made possible through the use of micro-location andgeo-fencing. A geofence around a smart appliance will notifythe appliance about entrance or exit of a user which can thenadjust itself accordingly.

C. Energy Efficiency

One of the driving forces behind the adoption of smart build-ings is the need for energy efficient buildings. Smart buildingsthrough the cooperation of various systems provide energyefficient solution and minimize the waste of energy. In order toobtain energy efficient smart buildings’ solutions, the buildingsand houses must be equipped with various capabilities suchas demand side management, storage of energy on a microlevel, the use of renewable energy sources on a micro leveland an electricity consumption controller that relies on pricesignals for providing efficient solutions [87]. Using system ofinteraction and IoT in smart buildings will allow the energyconsuming devices to be connected to Internet that will allowthe user to control and monitor various appliances through a

simple smartphone or any wireless terminal [88], [89]. Usingthe micro-location enabled services, a user’s location can beutilized by the energy consuming appliances hat can alsointeract among each other and act accordingly to optimize theresources i.e. using the least possible energy to provide theoptimal level of comfort to the tenant. System of interactionfacilitates the interaction of the devices and certainly will resultin a paradigm shift [90].

Micro-location enabled services can help increase the en-ergy efficiency of the IoT equipped smart buildings in twodifferent ways: a) reducing the waste of energy b) optimizingthe performance of the appliances and energy consumingdevices. In order to provide efficient tenant assistance, thetenant must be willing to subscribe to the services. Also thetenant’s position and his preferencs should be used to providethe solutions properly.

D. Disaster Management

In this text, we refer to disasters inflicted by natural phenom-ena (floods, tornados, storms), equipment failure (e.g. fire dueto a short circuit), or terrorist attacks. Traditional buildings arecharacterized by a low or non-existent level of preparednessfor disaster management. On the other hand, smart buildingscan mitigate or even completely eliminate the adverse effectsof such events. For example, in the case of a fire, in additionalto the fire alarm going off, the tenants will be alerted usingmicro-location enabled services, and the HVAC will turn offin the burning area so that the smoke cannot transfer to otherparts of the building.

Crowd sourcing can provide efficient disaster managementsolutions when it is used in smart buildings [91]. It can cer-tainly provide accurate data to the disaster managers which canthen be utilized for better management. Social Network Analy-sis can also be applied to inter link the objects for investigatingand deepening the understanding of IoT paradigm [92]. Thereare a number of ways to interlink IoT that can be analyzed


utilizing social network analysis. Such analysis can certainlyhelp in disaster management and provide efficient results.The utilized smart buildings framework tend to prioritize thegroup safety over the safety of an individual [93]. In order toimplement such systems, it is practically and ethically requiredthat the system should account for the uncertainty revolvingaround the clinical condition of every individual that can beobtained using a context aware micro-location enabled service.All of these services require high positioning accuracy, usuallyfiner than 1m. As we’ve shown in Table III, UWB and BLEcan provide accuracy as high as 10cm [57].

VI. CHALLENGES AND PROPOSED SOLUTION

The application of micro-location enabling technology andservices in IoT equipped smart buildings is supposed tomake things easier for the tenants, however there are certainchallenges that can serve as a hurdle in the efficient utilizationof micro-location enabled services. In this section we willdiscuss some of those challenges and propose solutions forthem.

A. Accuracy

Since the main purpose of using micro-location enablingtechnologies and services in any IoT equipped smart buildingis to locate any user within the building to provide efficientservices and solutions, the accuracy of the estimated positionis of significance. Micro-location enabling technologies aresupposed to have high accuracy so that the exact locationof the tenant can be found out. In past, various positioningtechnologies such as GPS [59], WLAN, Zigbee, Radio Fre-quency (RF), Infrared (IR), Ultrasounds or a hybrid of thesetechnologies [59] have been used to find out the position of theuser. These technologies can use different techniques such asRSSI, TDOA, and TOA [61] to provide the position of the user.These technologies are not as accurate as required for micro-location purposes (see table III). GPS is not suitable for indoorenvironment while the other technologies despite functioningin the indoor environments cannot attain high accuracy. Theaccuracy range is out of the required range and there issignificant room for improvement. Using various filteringtechniques can enhance the accuracy of various technologies.Although UWB based technologies have the highest accuracyas of now, beacon based micro-location services’ accuracy canbe enhanced by using filters such as Kalman Filter, ExtendedKalman Filter and Particle filters etc. There is need for furtherresearch to identify the optimal filter for micro-location andhow it can further be improved to give us the best possibleaccuracy.

B. Interoperability

As mentioned earlier, there are a number of micro-locationenabling technologies that can be used for provision of ef-ficient and effective solutions. These various micro-locationenabling entities lack interoperability. Following sub-sectionsclassifies the interoperability on the basis of various parame-ters.

1) Technologies: As of now, there are a number of micro-location enabling technologies available that were discussed insection III. All these technologies are different and utilizes dif-ferent concepts to location with a high accuracy. IoT requiresthe interconnectivity and interoperability of all the variousentities that constitute it. The end-user in an IoT equippedsmart building is not concerned about the technologies thatare used rather his position is of significant importance sincethat will enhance the comfort level and provide efficientservices. Therefore the interoperability of different micro-location enabling technologies is of significant importance.Currently existing micro-location enabling technologies arenot inter-operable i.e. a UWB based micro-location systemcannot be integrated with an ibeacon based system. The twosystems based on different technologies cannot function as oneunit. Similarly even within the iBeacon platform, there aredifferent vendors that provide ibeacon based micro-locationenabling services however they lack interoperability. Estimote[28] based ibeacon cannot be detected by Gimbal’s [44] mobileapplication and vice versa. This is because the vendors havetheir own frameworks and libraries that they use when they aredeveloping an application. This causes lack of interoperabilitybetween the ibeacons of different vendors.

2) Software Development Kits (SDKs): iBeacon vendorstend to provide their own SDKs, as a means of facilitatingthe development of applications. However, SDKs of differentvendors are different, and cause a vendor lock-in problem,i.e. the ibeacons of some other vendor cannot be incorporatedin the beacon network as they are tied to vendor basedSDK. In other words, application developers on iBeacons willhave to develop different applications for their applications tofunction under different vendors. This also leads to issues likeupgrading the iBeacons to a future generation might involveupdated the whole end-to-end system.

3) Protocols: Another challenge is that there are notstandardized protocols for micro-location enabling services.Considering again the case of iBeacons, we have observedtwo main protocols that are available both utilizing the BLEinterface. For example, Apple[45] owns the ibeacon closed-source protocol that specifies the packet and communicationstructure of the ibeacons and is only available to the ibeaconsmanufacturers. Similarly there are other vendors that provideBLE enabled beacons however they are not compatible withthe Apple’s standard. In such a scenario, the ibeacon will notwork with the beacons that are not as per the Apple standard.

Clearly, there is a need for protocols and standardization thatcan assist in the interoperability of technology wise differentbut task wise similar systems. All these devices have to work insync to attain the required common goal i.e. to provide micro-location enabled services. Making these different technologieswill also increase the overall system efficiency.

C. Privacy

One of the main concerns with the use of micro-locationenabling technologies and services is privacy. Although theyare supposed to provide efficient services to the tenants of anyIoT equipped building, revealing user’s location is a privacy


TABLE VSUMMARY OF CHALLENGES AND PROPOSED SOLUTIONS.

Challenge Description Proposed SolutionInteroperability Different micro-location enabling technolo-

gies are not inter-operable such as UWBmicro-location system cannot work in syncwith an iBeacon based micro-location sys-tem

There is a need for proper standardizationand protocols that can help in making dif-ferent technologies inter-operable

Privacy The tenant’s location information is sensi-tive and if used for any purpose other thanits specific use, can result in corruption ofuser privacy

Provision of guarantee to the user that hislocation will be only used for designatedpurposes as well as implementing strictslaws that can punish the violaters.

Energy Consumption The tenants might be reluctant to use themicro-location enabling technologies andservices due to the associated energy con-sumption

Develop micro-location enabling technolo-gies and services that are highly energyefficient. Also, there is need for improvingthe battery technology in order to providelong lasting performance .

Accuracy Micro-location requires high positioning ac-curacy to provide better services however asof now there are some accuracy issues withmicro-location enabling technologies

In order to improve accuracy, there is aneed for cutting edge research. Differentfiltering algorithms can be used to obtainbetter accuracy.

Security Security of the micro-location technologiesand services in IoT equipped smart buildingcan be under threat. Since some of thethese technologies can use cloud, so thetraditional security threats affiliated withthe cloud can affect micro-location enablingtechnologies

Checking the viability of distributed andcentralized security mechanisms.

Artificial Intelligence enabled devices The smartness of the devices should be en-hanced further to achieve the tasks requiredby micro-location enabling technologies andservices in IoT equipped smart buildings

Use of Artificial Intelligence based tech-niques improving the devices and enhancingtheir smartness.

issue. As of now, the micro-location enabling technologies andservices require the approval of the tenants and it is only afterthe tenant approves, such technologies then start operating.Most of the tenants might find it a breach of their privacyto let their location be traced through their smart phone orany other bluetooth enabled device, therefore they might bereluctant to use such technologies and services. This is amajor challenge as without tenant’s consent, the micro-locationenabling techologies can not reach its ultimate potential andmarket pentration might not be as expected. Furthermore, oncethe user’s position is obtained. The data might be stored andused for future use. This can help in analyzing the user interestand be used for contextual aware marketing etc. Howeverstoring the user data requires the data collection that needsto be properly handled [27]. Different sub-systems of theIoT and micro-location enabling technologies will interactwith the human beings and obtain data which needs to beproperly stored and taken care of. However it is importanto make sure that the data should not be used for maliciouspurposes. Policy broker [94] can be used to guarantee thatthe data is used specifically by the authorized agency for anauthorized task [27]. Policy broker uses proxy which interactswith user at one end and the services at the other. Thisguarantees that the user does not provide more informationthan required. Virtual Private Networks (VPNs) can also beused to secure the data within an organization [95] howeverthis is not feasible for IoT as it requires inter-connectivityaround the world. The integrity and confidentiality of the IoTcan also be improved using a Transport Layer Security (TLS).However every single Object Naming Service (ONS) wouldrequire a new TLS connection that affects the information

searching as new layers are added. DNS Security Extensions(DNSSEC), Onion Routing and Private Information Retrieval(PIR) discussed in [95] can also facilitate privacy protection.The location privacy solutions used in Vehicular Networkscan also be modified to be used for privacy issues in IoTand micro-location. The protocol proposed in [96] relies onthe creation of cryptographic mix-zones that can be used invarious points within a building. This will mitigate the threatof eaves droppers that are computationally constrained. Theirproposed protocol can be utilized efficient for the privacyprotection of the tenants of smart buildings.The pseudonymbased approach proposed in [97] can be used for energyaffluent IoT devices in smart buildings however it is notfeasible for energy constrained devices due to the complexityinvolved. The use of anonymous public keys presented in [98]for Vehicular Ad-Hoc Networks (VANETs) can also be usedfor IoT however it can not be used in its current form withmicro-location particularly with beacon based micro-location.The use of anonymous public keys can benefit IoT particularlyin disaster management scenarios as the message will bemostly safety messages that will not have any of the privateuser information.

In order to facilitate the growth of micro-location enablingtechnologies and services, the service providers must providethe tenant with a guarantee that the location information willbe only used to enhance the comfort level of the tenant andwill not be used for any other purpose. There is also a needfor strict laws and penalties if any service provider is foundviolating the user privacy by using the location information forany other purpose other than the agreement with the tenant.Winning the tenant trust is an important factor in the growth of


such technologies and services. The service providers can alsoattract the tenant’s attention by utilizing different markettingstrategies that will encourage the tenants to adopt the micro-location enabling technologies and services.

D. Energy Consumption

Enhancing the energy efficient of the micro-location en-abling technologies and services is of significant importanceas such technologies and services can be energy consuming.The energy consumption for micro-location can be dividedinto two broad categories.

1) Micro-location enabling devices: The devices used formicro-location such as the ibeacons, the UWB transceivers, themagnetic field mappers and the wireless positioning systemmust be energy efficient. The energy consumption of suchtechnologies can serve as a hurdle in its wide scale adoption.With the ibeacons particularly, its transmission power andtransmission time period can be adjusted to save energy atthe cost of performance. For energy consumption purposes,a device with lower transmission power and higher intervalbetween the transmission of beacons is favorable.

2) User Devices: The user device is one of the maincomponent of micro-location system. No matter what specificmicro-location enabling technology is used, the user deviceis the end device that can assist in providing the position ofthe user. Since the battery technology has not kept up withthe pace at which the other technologies have improved, opti-mizing the energy consumption of the device is an importantissue. The energy consumption of the devices differ based onthe micro-location enabling technology used.

a) BLE enabled devices: The BLE enabled devices dueto the presence of the BLE are less energy consuming. Thesedevices can communicate with the ibeacons and be used formicro-location purposes. When the ibeacon used, transmitswith a high time period then that will also enhance the energyefficiency of the user devices since it will have the ability tosleep for longer periods.

b) UWB: UWB compared to the Wi-Fi technologies pro-vide higher bandwidth, lower power consumption but shorterrange. They are also low cost [23]. However, the sstill consumea significant amoung of energy from battery limited devices,like smartphones, hence micro-location services need to takethis into account.

c) RFID: Although the passive RFIDs do not use anybattery, their range is shorter. Active RFIDs due to betterrange needs battery power. The reliance of range on battery(due to transmission power) certainly affects the performanceof the RFID. Although the smart phones as of now donot have RFID chips/tags [24], other user devices might beaffected adversely due to the energy consumption of the RFIDsystem. To the author’s knowledge the effect of the energyconsumption in micro-location services has not been studied.This is an important and open problem as these services arewidely deployed and contest for minimal energy resources.Simplifying the micro-location technologies without affectingtheir accuracy is an interesting research problem that has tobe addressed.

E. Security

Although the motive behind the use of micro-locationenabling technologies and services in the IoT equipped smartbuildings is to faciliate that tenant with efficient and reliabelsolutions, there are significant security challenges that threatenboth micro-location and IoT. The devices used for the pur-pose of micro-location are supposed to be cost-efficient andsimple to minimize the power utilization, which makes themvulnerable to various attacks. All these devices can act as apoint of entry for any attacker into the network therefore theirsecurity is an important issue. The two major security relatedproblems that IoT faces are data integrity and authentication[27]. While most of the prominent authentication mechanismsrely on the extensive exchange of messages, they are notfeasible for IoT and micro-location. A number of solutions arepresent in literature for sensor networks [99], however they arenot feasible in their current form for IoT. IoT also relies onthe communication among ’things’ so a fundamental challengethat it faces in terms of security is the man-in-the-middle attack[27]. Data integrity requires that the sent or received datashould not be modified in any form by any third party. Thedata should reach its destination without any manipulation.The problem of data integrity in sensor networks has beenstudied extensively and further information can be found in[100], however the devices in the IoT are mostly unattendedwhich adds more into the challenge. Adversaries can modifythe data either at the node or when it traverses in the network[27]. Memory protection in various tag technologies andsolutions is used as the precautionary step to save the datafrom being tampered at the node, while Keyed-Hash MessageAuthentication Code (HMAC) solution can be used to protectthe data while it is traversing across the network. Furtherinformation on security related issues of IoT with suggestedsolutions can be found in [2], [95], [101].

Authentication mechanisms can also facilitate the securityof IoT and micro-location. Current authentication mechanismsrely on the binding of an identity to a pre-shared secret (e.g.a password or generated random value), a RSA key pair andits associated X.509 certificate or one-time token passwords[102]. Such credentials may be prohibitive as they may beunmanned or the devices have such a small footprint, lackingin memory required to host the X.509 certificate and/or lackingin the CPU power to execute the cryptographic operationsto validate the X.509 certificates (or any type of Public Keyoperation).

More advanced security challenges exist: as a plethora ofindoor sensor, actuators and embedded systems are deployedin smart buildings, they need to adhere to a single commonstandard in order to facilitate zero-tough configuration andprovisioning; The scalability of micro-location enabled ser-vices in an IoT equipped smart building brings new challengesas deployments must now serve millions huge number ofendpoints. Similarly for IoT, serving a rich multi-service edgealong with all the required policies to serve the differentmillions endpoints forces larger and more distributed scaledeployments than the classical IT.

Such a reality teaches us that a perfect secure solution is


unlikely to be achieved at any level. A real-time intelligentsecurity and risk management capability provides a comple-mentary solution to address the security gaps and threats.Hence, a flexible security framework is required. Any micro-location enabling technology or service deployment mustencompass the following components: (a) Authentication; (b)Authorization and Access Control and (c) Network EnforcedPolicy.

For sake of context aware services, user’s information issaved on the cloud and is meant to be used for marketingpurposes however it can used for non-relevant purposes inany way that can be hazardous to the overall system. Also dueto various network attacks, precious data can be manipulatedand exposed that can not only affect the seller but also theuser. With the advent of beacon based LBS, a new windowof marketing has opened up however its security has to betightened and the privacy concerns of the users should behandled as well.

The traditional security protocols and methods cannot guar-antee the security of micro-location enabling technologies andservices in IoT equipped smart buildings and there is needfor cutting edge research to properly secure the network.While securing the network, it should also be made surethat the proposed solution is practically implementable onenergy constrained devices. The security mechanism shouldbe reliable as well as quick. Furthermore, those micro-locationenabling technologies and services that use the cloud fordata storage and other tasks face the challenges that anytypical cloud based application will so the traditional securitysolutions applied for security of the cloud can be applied hereas well.

F. Artificial Intelligence enabled devices

Micro-location enabled services in an IoT equipped smartbuilding are meant to enhance the tenant satisfaction andincrease the overall efficiency. Due to the expected increase infuture use and the overall demand of the users for intelligentand autonomous systems that will facilitate the user, there isneed for enhancing the device smartness. A smart device willuse user’s positioning in an effective way to fulfill the tasks.In the absence of device smartness, a user might be alertedabout a particular grocery to buy based on his position whichmight not be the best possible option in terms of price howeverwith the added intelligence in device, the device can find theoptimum option for the user taking a number of parametersinto account. This is one of the envisioned micro-locationenabled services. Similarly the user’s past location can be ofuse in predicting his future location that can be then used toprovide contextual aware information with better reliability.Such services that are to be provided in an IoT equipped smartbuilding are challenging and require the devices to exhibithigher level of smartness than the current level in order toaccomplish their envisioned tasks in the future smart buildings.The use of Artificial Intelligence (AI) algorithms can certainlyhelp in enhancing the smartness of the devices. FormulatingAI algorithms that are less complex while simultaneouslyenhances the smartness is challenging task. Such algorithms

will equip the devices to properly accomplish their tasks inthe current and envisioned micro-location enabled services inIoT equipped smart buildings. Table V provides a summaryof the challenges and the proposed solutions.

VII. CONCLUSION

In this paper, we focused on micro-location enabling tech-nologies and services for an IoT equipped smart building. Wedescribed various micro-location enabling technologies thatare used right now. We argued that using such micro-locationenabling technologies in an IoT equipped smart buildings, wecan provide the tenant with a wide range of services thatwill enhance the comfort level as well as increase efficiencyof the overall system. We presented some of the micro-location enabled services and described some example usecases. Using the micro-location enabled services can open thedoor to various novel services that are only possibly due to theintegration of the IoT within a smart building. Recently therehave been advancements in the field of micro-location andvarious new technologies and techniques have been proposed.However, these advancements come with several challenges.For example, security, and privacy, as well as accuracy andenergy consumption of the devices provide avenues for inter-esting research problems. To conclude, we believe that micro-location enabling technologies and services in IoT equippedsmart buildings have a huge potential.

REFERENCES

[1] O. Evangelatos, K. Samarasinghe, and J. Rolim, “Evaluating designapproaches for smart building systems,” in Mobile Adhoc and SensorSystems (MASS), 2012 IEEE 9th International Conference on. IEEE,2012, pp. 1–7.

[2] J. Gubbi, R. Buyya, S. Marusic, and M. Palaniswami, “Internet ofThings (IoT): A vision, architectural elements, and future directions,”Future Generation Computer Systems, vol. 29, no. 7, pp. 1645–1660,2013.

[3] K. Figueredo, “Connected Living: Realising the Market Potential,”http://www.gsma.com/connectedliving/wp-content/uploads/2012/05/1-Ken-Figueredo-Introduction.pdf, [Online; accessed 23-Nov-2014].

[4] Telecoms, “MNOs are already making the IoTconnection!” http://www.telecoms.com/166122/mnos-are-already-making-the-iot-connection/, [Online; accessed9-Dec-2014].

[5] D. C. T. National Intelligence Council, “Six Technologies with Po-tential Impacts on US Interests Out to 2025 Conference Report CR2008-07,,” http://www.dni.gov/nic/NIC home.html, 2008.

[6] D. Snoonian, “Smart buildings,” Spectrum, IEEE, vol. 40, no. 8, pp.18–23, 2003.

[7] I. for Building Efficiency, “What is a Smart Building,” http://www.institutebe.com/smart-grid-smart-building/What-is-a-Smart-Building.aspx, 2008, [Online; accessed 02-Sept-2014].

[8] R. Yin, P. Xu, and P. Shen, “Case study: Energy savings from solarwindow film in two commercial buildings in shanghai,” Energy andBuildings, vol. 45, pp. 132–140, 2012.

[9] Y. He, Y. Liu, X. Shen, L. Mo, and G. Dai, “Noninteractive localizationof wireless camera sensors with mobile beacon,” Mobile Computing,IEEE Transactions on, vol. 12, no. 2, pp. 333–345, 2013.

[10] Z. Yang, L. Jian, C. Wu, and Y. Liu, “Beyond triangle inequality:sifting noisy and outlier distance measurements for localization,” ACMTransactions on Sensor Networks (TOSN), vol. 9, no. 2, p. 26, 2013.

[11] Contiki, “The Opensource OS for the Internet of Things,” http://www.contiki-os.org/, [Online; accessed 19-Sept-2014].

[12] A. Dunkels, “Rime-a lightweight layered communication stack forsensor networks.” 2007.

[13] K. Ashton, “That internet of things thing,” RFiD Journal, vol. 22, pp.97–114, 2009.

http://www.gsma.com/connectedliving/wp-content/uploads/2012/05/1-Ken-Figueredo-Introduction.pdf

http://www.gsma.com/connectedliving/wp-content/uploads/2012/05/1-Ken-Figueredo-Introduction.pdf

http://www.telecoms.com/166122/mnos-are-already-making-the-iot-connection/

http://www.telecoms.com/166122/mnos-are-already-making-the-iot-connection/

http://www.dni.gov/ nic/NIC_home.html

http://www.institutebe.com/smart-grid-smart-building/What-is-a-Smart-Building.aspx



http://www.contiki-os.org/

http://www.contiki-os.org/


[14] D. Giusto, A. Lera, G. Morabito, and L. Atzori, The Internet of Things.Springer, 2010.

[15] O. Vermesan and P. Friess, Internet of things: converging technologiesfor smart environments and integrated ecosystems. River Publishers,2013.

[16] S. C. Ergen, “Zigbee/IEEE 802.15. 4 summary,” UC Berkeley, Septem-ber, vol. 10, 2004.

[17] J. A. Gutierrez, M. Naeve, E. Callaway, M. Bourgeois, V. Mitter, andB. Heile, “IEEE 802.15. 4: a developing standard for low-power low-cost wireless personal area networks,” network, IEEE, vol. 15, no. 5,pp. 12–19, 2001.

[18] Intel, “Wireless LAN standards study,” http://www.intel.com/content/dam/www/public/us/en/documents/case-studies/802-11-wireless-lan-standards-study.pdf, [Online; accessed 03-Sept-2014].

[19] I. Papapanagiotou, G. S. Paschos, S. A. Kotsopoulos, and M. Devetsiki-otis, “Extension and comparison of QoS-enabled Wi-Fi models in thepresence of errors,” in Global Telecommunications Conference, 2007.GLOBECOM ’07. IEEE, nov. 2007, pp. 2530 –2535.

[20] I. Papapanagiotou, D. Toumpakaris, J. Lee, and M. Devetsikiotis,“A survey on next generation mobile WiMAX networks: objectives,features and technical challenges,” IEEE Communications SurveysTutorials, vol. 11, no. 4, pp. 3 –18, quarter 2009.

[21] S. Sesia, I. Toufik, and M. Baker, LTE: the UMTS long term evolution.Wiley Online Library, 2009.

[22] A. Ghosh, R. Ratasuk, B. Mondal, N. Mangalvedhe, and T. Thomas,“LTE-Advanced: next-generation wireless broadband technology [in-vited paper],” Wireless Communications, IEEE, vol. 17, no. 3, pp. 10–22, 2010.

[23] M. Shaik, “Ultra Wide-Band vs. Wi-Fi A Study and Comparison ofthe two technologies,” [Online; accessed 12-Dec-2014].

[24] S. Nadler, V. Soroka, O. Fuchs, R. Korenshtein, and E. Sonsino,“Presence zones for contextual location based services.”

[25] V. Pillai, H. Heinrich, D. Dieska, P. V. Nikitin, R. Martinez, and K. S.Rao, “An ultra-low-power long range battery/passive RFID tag for UHFand microwave bands with a current consumption of 700 na at 1.5 v,”Circuits and Systems I: Regular Papers, IEEE Transactions on, vol. 54,no. 7, pp. 1500–1512, 2007.

[26] W. Alliance, “How far does a Wi-Fi Direct connec-tion travel?” http://www.wi-fi.org/knowledge-center/faq/how-far-does-a-wi-fi-direct-connection-travel, [Online; accessed22-Apr-2014].

[27] L. Atzori, A. Iera, and G. Morabito, “The internet of things: A survey,”Computer networks, vol. 54, no. 15, pp. 2787–2805, 2010.

[28] Estimote, “Estimote real world context for your apps,” http://www.estimote.com, [Online; accessed 26-Sept-2014].

[29] F. Faheem, S. Mahmud, G. Khan, M. Rahman, and H. Zafar, “A surveyof intelligent car parking system,” Journal of applied research andtechnology, vol. 11, no. 5, 2013.

[30] R. J. Weiland and L. B. Purser, “Intelligent transportation systems,”Transportation in the new millennium, 2000.

[31] I. Bayram and I. Papapanagiotou, “A survey on communicationtechnologies and requirements for internet of electric vehicles,”EURASIP Journal on Wireless Communications and Networking,vol. 2014, no. 1, p. 223, 2014. [Online]. Available: http://jwcn.eurasipjournals.com/content/2014/1/223

[32] I. S. Bayram, G. Michailidis, I. Papapanagiotou, and M. Devetsiki-otis, “Decentralized control of electric vehicles in a network of fastcharging stations,” Globecom 2013-Symposium on Selected Areas inCommunications (GC13 SAC), 2013.

[33] P. I. Project, “The Internet of Things Will Thrive by 2025,” http://www.pewinternet.org/2014/05/14/internet-of-things/, [Online; accessed23-Nov-2014].

[34] I. Papapanagiotou, E. M. Nahum, and V. Pappas, “Configuring DHCPleases in the smartphone era,” in International Measurement Confer-ence, ser. IMC ’12. ACM, Nov. 2012.

[35] ——, “Smartphones vs. laptops: comparing web browsing behaviorand the implications for caching,” in Proceedings of the 12th ACMSIGMETRICS/PERFORMANCE joint international conference onMeasurement and Modeling of Computer Systems, ser. SIGMETRICS’12. New York, NY, USA: ACM, 2012, pp. 423–424. [Online].Available: http://doi.acm.org/10.1145/2254756.2254824

[36] Cisco, “IPv6,” http://www.cisco.com/web/solutions/trends/ipv6/index.html, [Online; accessed 06-Sept-2014].

[37] L. Yan, Y. Zhang, L. T. Yang, and H. Ning, The Internet of things:from RFID to the next-generation pervasive networked systems. CRCPress, 2008.

[38] D. Miorandi, S. Sicari, F. De Pellegrini, and I. Chlamtac, “Internet ofthings: Vision, applications and research challenges,” Ad Hoc Networks,vol. 10, no. 7, pp. 1497–1516, 2012.

[39] R. Brennan, W. Tai, D. O’sullivan, M. S. Aslam, S. Rea, and D. Pesch,“Open framework middleware for intelligent WSN topology adaptionin smart buildings,” in Ultra Modern Telecommunications & Work-shops, 2009. ICUMT’09. International Conference on. IEEE, 2009,pp. 1–7.

[40] L. R. Suzuki, K. Brown, S. Pipes, and J. Ibbotson, “Smart buildingmanagement through augmented reality,” in Pervasive Computing andCommunications Workshops (PERCOM Workshops), 2014 IEEE Inter-national Conference on. IEEE, 2014, pp. 105–110.

[41] A. LaMarca, Y. Chawathe, S. Consolvo, J. Hightower, I. Smith, J. Scott,T. Sohn, J. Howard, J. Hughes, F. Potter et al., “Place lab: Devicepositioning using radio beacons in the wild,” in Pervasive computing.Springer, 2005, pp. 116–133.

[42] D. Namiot and M. Sneps-Sneppe, “Geofence and network proximity,”in Internet of Things, Smart Spaces, and Next Generation Networking.Springer, 2013, pp. 117–127.

[43] Google, “Search Trend,” https://www.google.com/trends/explore#q=Internet%20of%20Things%2C%20%2Fm%2F09g9zkw%2C%20Smart%20Grid%2C%20Sensor%20Networks&cmpt=q, [Online;accessed 04-Oct-2014].

[44] Gimbal, “Context aware platform,” http://www.gimbal.com/, [Online;accessed 15-Sept-2014].

[45] Apple, “iBeacons for Developers,” https://developer.apple.com/ibeacon/, [Online; accessed 15-Sept-2014].

[46] G. C. Platform, “Internet of Things,” https://cloud.google.com/solutions/iot/, [Online; accessed 19-May-2015].

[47] Cisco, “Internet of Things (IoT),” http://www.cisco.com/web/solutions/trends/iot/overview.html, [Online; accessed 30-Dec-2014].

[48] IBM, “System of Interaction,” http://www-01.ibm.com/software/solutions/systems-of-interaction/, [Online; accessed 19-Sept-2014].

[49] U. Bareth, A. Kupper, and P. Ruppel, “Geoxmart-a marketplace forgeofence-based mobile services,” in Computer Software and Applica-tions Conference (COMPSAC), 2010 IEEE 34th Annual. IEEE, 2010,pp. 101–106.

[50] F. Reclus and K. Drouard, “Geofencing for fleet & freight manage-ment,” in Intelligent Transport Systems Telecommunications,(ITST),2009 9th International Conference on. IEEE, 2009, pp. 353–356.

[51] M. Siekkinen, M. Hiienkari, J. K. Nurminen, and J. Nieminen, “Howlow energy is bluetooth low energy? comparative measurements withZigBee/802.15. 4,” in Wireless Communications and Networking Con-ference Workshops (WCNCW), 2012 IEEE. IEEE, 2012, pp. 232–237.

[52] PassKit, “How Does iBeacon Work?” https://passkit.com/how-ibeacon-works/, [Online; accessed 11-Nov-2014].

[53] Apple, “Getting started with iBeacon,” https://developer.apple.com/ibeacon/Getting-Started-with-iBeacon.pdf, [Online; accessed 11-Nov-2014].

[54] M. B. Journal, “Ole Miss offering new beacon technologyfor sports fans,” http://msbusiness.com/blog/2014/07/08/ole-miss-offering-new-system-sports-fans/, [Online; accessed 15-Sept-2014].

[55] D. Consulting, “The Dawn of Mobile Influence,” http://www.deloitte.com/assets/Dcom-UnitedStates/Local%20Assets/Documents/RetailDistribution/us retail Mobile-Influence-Factor 062712.pdf,[Online; accessed 15-Sept-2014].

[56] J.-S. Lee, Y.-W. Su, and C.-C. Shen, “A comparative study of wirelessprotocols: Bluetooth, UWB, ZigBee, and Wi-Fi,” in Industrial Elec-tronics Society, 2007. IECON 2007. 33rd Annual Conference of theIEEE. IEEE, 2007, pp. 46–51.

[57] Decawave, “Real Time Location: An Introduction,” http://www.decawave.com/sites/default/files/resources/aps003 dw1000rtls introduction.pdf, [Online; accessed 1-Dec-2014].

[58] IndoorAtlas, “Ambient magnetic field-based indoor location technologybringing the compass to the next level,” July 2012, White Paper.

[59] Y. Wang, “Performance analysis of smart space with indoor localizationcapabilities.” Master’s thesis, North Carolina State University, USA,2014.

[60] S. Gezici, Z. Tian, G. B. Giannakis, H. Kobayashi, A. F. Molisch,H. V. Poor, and Z. Sahinoglu, “Localization via Ultra-Wideband radios:a look at positioning aspects for future sensor networks,” SignalProcessing Magazine, IEEE, vol. 22, no. 4, pp. 70–84, 2005.

[61] C.-C. Chong, I. Guvenc, F. Watanabe, and H. Inamura, “Ranging andlocalization by UWB radio for indoor LBS,” NTT DOCOMO TechnicalJournal (English version), vol. 11, no. 1, pp. 41–48, 2009.

http://www.intel.com/content/dam/www/public/us/en/documents/case-studies/802-11-wireless-lan-standards-study.pdf



http://www.wi-fi.org/knowledge-center/faq/how-far-does-a-wi-fi-direct-connection-travel

http://www.wi-fi.org/knowledge-center/faq/how-far-does-a-wi-fi-direct-connection-travel

http://www.estimote.com

http://www.estimote.com

http://jwcn.eurasipjournals.com/content/2014/1/223

http://jwcn.eurasipjournals.com/content/2014/1/223

http://www.pewinternet.org/2014/05/14/internet-of-things/

http://www.pewinternet.org/2014/05/14/internet-of-things/

http://doi.acm.org/10.1145/2254756.2254824

http://www.cisco.com/web/solutions/trends/ipv6/index.html

http://www.cisco.com/web/solutions/trends/ipv6/index.html

https://www.google.com/trends/explore#q=Internet%20of%20Things%2C%20%2Fm%2F09g9zkw%2C%20Smart%20Grid%2C%20Sensor%20Networks&cmpt=q



http://www.gimbal.com/

https://developer.apple.com/ibeacon/

https://developer.apple.com/ibeacon/

https://cloud.google.com/solutions/iot/

https://cloud.google.com/solutions/iot/

http://www.cisco.com/web/solutions/trends/iot/overview.html

http://www.cisco.com/web/solutions/trends/iot/overview.html

http://www-01.ibm.com/software/solutions/systems-of-interaction/

http://www-01.ibm.com/software/solutions/systems-of-interaction/

https://passkit.com/how-ibeacon-works/

https://passkit.com/how-ibeacon-works/

https://developer.apple.com/ibeacon/Getting-Started-with-iBeacon.pdf

https://developer.apple.com/ibeacon/Getting-Started-with-iBeacon.pdf

http://msbusiness.com/blog/2014/07/08/ole-miss-offering-new-system-sports-fans/

http://msbusiness.com/blog/2014/07/08/ole-miss-offering-new-system-sports-fans/

http://www.deloitte.com/assets/Dcom-UnitedStates/Local%20Assets/Documents/RetailDistribution/us_retail_Mobile-Influence-Factor_062712.pdf



http://www.decawave.com/sites/default/files/resources/aps003_dw1000_rtls_introduction.pdf




[62] T. Manodham, L. Loyola, and T. Miki, “A novel wireless position-ing system for seamless internet connectivity based on the WLANinfrastructure,” Wireless Personal Communications, vol. 44, no. 3, pp.295–309, 2008.

[63] C. Wu, Z. Yang, Y. Liu, and W. Xi, “WILL: Wireless indoor local-ization without site survey,” Parallel and Distributed Systems, IEEETransactions on, vol. 24, no. 4, pp. 839–848, 2013.

[64] Y. Desmedt, “Man-in-the-middle attack,” in Encyclopedia of Cryptog-raphy and Security. Springer, 2011, pp. 759–759.

[65] OnxyBeacon, “OnxyBeacon helps you develop context aware mobileapps,” http://www.onyxbeacon.com/, [Online; accessed 15-Sept-2014].

[66] Swirl, “Secure Cast beacons,” http://www.swirl.com/platform.html,[Online; accessed 15-Sept-2014].

[67] S. Notify, “Join the companies that have been leveraging our enterpriseproximity solution for the past two years.” https://sonicnotify.com/l,[Online; accessed 15-Sept-2014].

[68] IndoorAtlas, “Game Changing Indoor Location,” https://www.indooratlas.com/, [Online; accessed 15-Sept-2014].

[69] L. M. Ni, Y. Liu, Y. C. Lau, and A. P. Patil, “LANDMARC: indoorlocation sensing using active RFID,” Wireless networks, vol. 10, no. 6,pp. 701–710, 2004.

[70] B. Rekha, “Location is personal,” Geospatial World, vol. 6, pp. 31–38,2011.

[71] Google, “Google Wireless Positioning System,” www.google.com,[Online; accessed 14-Sept-2014].

[72] AlterGeo, “AlterGeo Positioning Solutions,” http://platform.altergeo.ru/index.php?mode=products, [Online; accessed 14-Sept-2014].

[73] Skyhook, http://www.skyhookwireless.com/apps-enterprise/, [Online;accessed 14-Sept-2014].

[74] Navizon, “Navizon Indoors for Navigation,” http://www.navizon.com/product-navizon-indoors-navigation, [Online; accessed 14-Sept-2014].

[75] Infsoft, “Infsoft Wireless Positioning Solutions,” http://www.infsoft.com/, [Online; accessed 14-Sept-2014].

[76] Combain, “Combain Positioning Solutions,” http://www.combain.com/,[Online; accessed 14-Sept-2014].

[77] H. Liu, H. Darabi, P. Banerjee, and J. Liu, “Survey of wireless indoorpositioning techniques and systems,” Systems, Man, and Cybernetics,Part C: Applications and Reviews, IEEE Transactions on, vol. 37, no. 6,pp. 1067–1080, 2007.

[78] B. T. Fang, “Simple solutions for hyperbolic and related position fixes,”Aerospace and Electronic Systems, IEEE Transactions on, vol. 26,no. 5, pp. 748–753, 1990.

[79] M. Kanaan and K. Pahlavan, “A comparison of wireless geolocationalgorithms in the indoor environment,” in Wireless Communicationsand Networking Conference, 2004. WCNC. 2004 IEEE, vol. 1, March2004, pp. 177–182 Vol.1.

[80] A. Teuber, B. Eissfeller, and T. Pany, “A two-stage fuzzy logic approachfor wireless LAN indoor positioning,” in Proc. IEEE/ION PositionLocation Navigat. Symp, vol. 4, 2006, pp. 730–738.

[81] A. Gunther and C. Hoene, “Measuring round trip times to determine thedistance between WLAN nodes,” in NETWORKING 2005. NetworkingTechnologies, Services, and Protocols; Performance of Computer andCommunication Networks; Mobile and Wireless Communications Sys-tems. Springer, 2005, pp. 768–779.

[82] IBM, “Delivering System of Interaction,” http://www.slideshare.net/ibmsverige/systems-of-interaction, [Online; accessed 19-Sept-2014].

[83] D. Martin, A. Alzua, and C. Lamsfus, “A contextual geofencing mobiletourism service,” in ENTER, 2011, pp. 191–202.

[84] F. Beckley and M. Ward, “Device and network enabled geo-fencingfor area sensitive gaming enablement,” Dec. 30 2005, US Patent App.11/323,265.

[85] L. S. Humphries and H.-J. Ngo, “Method and system for tracked devicelocation and route adherence via geofencing,” Jan. 16 2007, US Patent7,164,986.

[86] T. Verge, “San Francisco Airport testing beacon system forblind travelers,” http://www.theverge.com/2014/7/31/5956265/san-francisco-airport-testing-beacon-system-for-blind-travelers,[Online; accessed 29-Sept-2014].

[87] B. Morvaj, L. Lugaric, and S. Krajcar, “Demonstrating smart buildingsand smart grid features in a smart energy city,” in Energetics (IYCE),Proceedings of the 2011 3rd International Youth Conference on. IEEE,2011, pp. 1–8.

[88] S.-J. Jeon, S.-Y. Ko, J.-H. Park, and M.-K. Youn, “Remotely controllingappliances using a wireless terminal,” 2004.

[89] H. Y. Amro, J. P. Dodson, G. Kraft IV, and K. R. Taylor, “Method andsystem for remotely controlling an appliance using a personal digitalassistant,” Jan. 14 2003, uS Patent 6,507,762.

[90] S. Haller, S. Karnouskos, and C. Schroth, The internet of things in anenterprise context. Springer, 2009.

[91] E. Asimakopoulou and N. Bessis, “Buildings and crowds: Formingsmart cities for more effective disaster management,” in InnovativeMobile and Internet Services in Ubiquitous Computing (IMIS), 2011Fifth International Conference on. IEEE, 2011, pp. 229–234.

[92] A. Zelenkauskaite, N. Bessis, S. Sotiriadis, and E. Asimakopoulou,“Interconnectedness of complex systems of internet of things throughsocial network analysis for disaster management,” in Intelligent Net-working and Collaborative Systems (INCoS), 2012 4th InternationalConference on. IEEE, 2012, pp. 503–508.

[93] H. Borrion, T. Mitchener-Nissen, J. Taylor, and K.-M. Lai, “Counteringbioterrorism: Why smart buildings should have a code of ethics,”in Intelligence and Security Informatics Conference (EISIC), 2012European. IEEE, 2012, pp. 68–75.

[94] G. V. Lioudakis, E. A. Koutsoloukas, N. Dellas, S. Kapellaki, G. N.Prezerakos, D. I. Kaklamani, and I. S. Venieris, “A proxy for privacy:the discreet box,” in EUROCON, 2007. The International Conferenceon &# 34; Computer as a Tool&# 34;. IEEE, 2007, pp. 966–973.

[95] R. H. Weber, “Internet of things–new security and privacy challenges,”Computer Law & Security Review, vol. 26, no. 1, pp. 23–30, 2010.

[96] J. Freudiger, M. Raya, M. Felegyhazi, P. Papadimitratos et al., “Mix-zones for location privacy in vehicular networks,” in Proceedings ofthe first international workshop on wireless networking for intelligenttransportation systems (Win-ITS), 2007.

[97] P. Papadimitratos, L. Buttyan, J.-P. Hubaux, F. Kargl, A. Kung, andM. Raya, “Architecture for secure and private vehicular communi-cations,” in Telecommunications, 2007. ITST’07. 7th InternationalConference on ITS. IEEE, 2007, pp. 1–6.

[98] M. Raya and J.-P. Hubaux, “Securing vehicular ad hoc networks,”Journal of Computer Security, vol. 15, no. 1, pp. 39–68, 2007.

[99] L. Eschenauer and V. D. Gligor, “A key-management scheme fordistributed sensor networks,” in Proceedings of the 9th ACM conferenceon Computer and communications security. ACM, 2002, pp. 41–47.

[100] R. Acharya and K. Asha, “Data integrity and intrusion detection inwireless sensor networks,” in Networks, 2008. ICON 2008. 16th IEEEInternational Conference on. IEEE, 2008, pp. 1–5.

[101] C. M. Medaglia and A. Serbanati, “An overview of privacy and securityissues in the internet of things,” in The Internet of Things. Springer,2010, pp. 389–395.

[102] M. Myers, R. Ankney, A. Malpani, S. Galperin, and C. Adams, “X.509 internet public key infrastructure online certificate status protocol-ocsp,” RFC 2560, Tech. Rep., 1999.

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