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Micro-location for Internet of Things equipped Smart Buildings

Faheem Zafari, Ioannis Papapanagiotou, Konstantinos Christidis

arXiv:1501.01539v2cs.OH

TL;DR

The paper addresses how micro-location and geofencing can be integrated with IoT-equipped smart buildings to support tenants and building control. It surveys enabling technologies and services, discusses integration challenges and potential solutions, and reports that technologies such as UWB and BLE can provide accuracy as high as 10cm for services requiring positioning finer than 1m.

  • Problem

    Integrating micro-location technologies and services thoroughly with IoT-equipped smart buildings remains challenging, including issues involving sensor management, security, and energy consumption.

  • Method

    The paper surveys micro-location enabling technologies and services, describes example use cases, and discusses challenges with potential general solutions.

  • Results

    UWB and BLE can provide accuracy as high as 10cm, supporting services that require positioning finer than 1m.

  • Takeaways & Limitations

    Micro-location-enabled services can enhance tenant comfort and overall system efficiency while enabling novel services through IoT integration in smart buildings.

Abstract

from arXiv · show

Micro-location is the process of locating any entity with high accuracy (possibly in centimeters), while geofencing is the process of creating a virtual fence around a so-called Point of Interest (PoI). In this paper, we present an insight into various micro-location enabling technologies and services. We also discuss how these can accelerate the incorporation of Internet of Things (IoT) in smart buildings. We argue that micro-location based location-aware solutions can play a significant role in facilitating the tenants of an IoT equipped smart building. Also, such advanced technologies will enable the smart building control system through minimal actions performed by the tenants. We also highlight the existing and envisioned services to be provided by using micro-location enabling technologies. We describe the challenges and propose some potential solutions such that micro-location enabling technologies and services are thoroughly integrated with IoT equipped smart building.

I. INTRODUCTION

The paper situates micro-location as an enabling capability for IoT-equipped smart buildings, where precise tenant positioning can support comfort, efficiency, and context-aware services. It surveys enabling technologies and services while identifying integration challenges and possible solutions.

  • I. INTRODUCTION: Micro-location locates entities with centimeter-level accuracy, while geofencing creates a virtual boundary around a Point of Interest.Within smart buildings, tenant position can support effective and efficient solutions.
  • I. INTRODUCTION: The paper surveys micro-location technologies that can assist IoT-equipped smart buildings.This is presented as a primary contribution and the paper’s organizing focus.
  • I. INTRODUCTION: It reviews current and envisioned micro-location-enabled services intended to enhance tenants’ experience.The paper also describes example services and use cases.
  • I. INTRODUCTION: The paper identifies challenges to incorporating micro-location into IoT-equipped smart buildings and discusses possible general solutions.The stated challenges include integration across advanced building systems and technologies.
  • I. INTRODUCTION: Smart buildings interconnect subsystems, tenants, other buildings, and smart grids to optimize performance and provide services while supporting energy efficiency and comfort.Their systems use information sharing to interact with tenants and coordinate building functions.
  • I. INTRODUCTION: IoT-equipped smart buildings combine building automation technologies, wireless sensor networks, and communication standards to connect and manage building subsystems.The paper discusses BACnet, LonWorks, and IP- and non-IP-based wireless sensor-network approaches.

B. Internet of Things

The Internet of Things connects sensors, smartphones, actuators, and other physical entities through the Internet across residential and commercial settings. In smart buildings, this connectivity supports diverse services but also creates interoperability, security, privacy, energy, processing, and addressing challenges.

  • B. Internet of Things: IoT interconnects sensors, smartphones, actuators, and tagged or embedded physical objects through the Internet.Cooperation among these devices forms the basic pillar of IoT.
  • B. Internet of Things: IoT services span residential and commercial applications including e-health, e-marketing, intelligent parking, transportation, automation, and logistics.The paper presents these as examples of current application areas.
  • B. Internet of Things: IoT infrastructure connects devices and systems across residential, transportation, enterprise, and healthcare environments through the Internet.Figure 2 is described as an exemplar of this interconnected infrastructure.
  • B. Internet of Things: IoT integration faces challenges involving device interoperability, smartness, security, privacy, energy consumption, processing capability, and network addressing.Managing large numbers of sensor nodes is also identified as an issue in smart-building deployments.
  • B. Internet of Things: Integrating IoT into smart buildings can improve indoor-environment experiences, support tenant comfort, and enable reliable and efficient interaction with building entities.The passage also associates these solutions with potential revenue sources.

C. Application Layer Technologies

IoT application-layer technologies support constrained devices and networks while enabling BLE beacon-based proximity services and context-aware building interactions. The section also highlights sensor-management, interoperability, privacy, and security considerations.

  • Application-layer constraints: IoT application-layer devices operate under constraints including limited energy, memory, processing capability, packet sizes, and network reliability.These devices may sleep and wake briefly while operating in networks that must scale to many devices.
  • Application-layer constraints: The CoRE working group standardizes frameworks for manipulating minimal resources in constrained environments, including sensors and actuators.Examples include temperature sensors, power meters, light switches, heating controllers, and door locks.
  • BLE beacons: BLE iBeacons periodically advertise signals that BLE-enabled devices detect for proximity-based positioning inside buildings.BLE’s low energy consumption supports beacon operation on small devices.
  • BLE beacons: iBeacon packets use a mandatory UUID plus optional major and minor values to identify beacons by brand, locality, and department.The major and minor values provide hierarchical beacon identification.
  • BLE beacons: BLE proximity estimation uses RSSI, with ranging categories of immediate, near, far, and unknown.The near range is approximately 1–3m with line of sight, while obstructions can cause false range detection.
  • Location-aware services: Beacon-enabled micro-location supports context-aware services such as targeted offers, building automation, navigation assistance, and tenant-specific environmental control.Examples include coupons for customers and automatic activation of office computers and HVAC systems when a manager enters a geofence.

B. Ultra-Wideband Based Micro-location

Ultra-Wideband is characterized by very large fractional or absolute bandwidths, which support reliable communications and radar applications. Its wide frequency range also lowers power spectral density and can improve obstacle handling.

  • UWB characteristics: Wide UWB bandwidth can improve reliability by increasing the probability that signals propagate around obstacles.The signal spans many frequencies, supporting communications and radar applications.
  • UWB characteristics: Spreading signal power across many frequencies reduces UWB power spectral density.

1) Ranging:

Ranging estimates distances or angles between nodes, after which localization methods estimate a mobile device’s position. UWB commonly uses TOA because its bandwidth provides high time-domain resolution, with reported accuracy as high as 10cm.

  • Ranging: Ranging estimates distances or angles between two nodes using AOA, RSS, TOA, or hybrid techniques.
  • Ranging: UWB’s wide bandwidth provides high time-domain resolution, motivating TOA-based techniques for ranging.The passage associates this resolution with sub-centimeter resolution ability.
  • Localization: Range estimates between fixed and mobile devices precede localization, which estimates the mobile device’s position using methods such as NLS.The fixed device is a UWB access point, while the mobile device may be a smartphone or sensor.
  • Localization: 10cm is the reported maximum accuracy for UWB-based micro-location.
  • Alternative positioning: Wireless positioning systems use cellular towers outdoors and Wi-Fi access points indoors, with AOA, TDOA, and E-OTD among their positioning techniques.

E. Radio Frequency Identification (RFID)

RFID uses readers and tags to store and retrieve data through electromagnetic transmission, with active and passive implementations. Positioning can use passive RFID alongside Wi-Fi and NFC, while localization systems also distinguish location representations and geometric methods.

  • RFID fundamentals: RFID systems comprise readers, tags, and communication protocols for electromagnetic data storage and retrieval.Readers retrieve data emitted by tags.
  • RFID types: Active RFID tags use batteries and radio transceivers to achieve greater range.
  • RFID types: Passive RFID tags operate without batteries by reflecting reader-transmitted RF signals, offering lower cost and weight but limited range.They can support positioning when triangulated with Wi-Fi and NFC.
  • Location representations: Location may be represented as physical, symbolic, absolute, or relative, independently of the positioning technology.Relative location expresses proximity to a known object, while symbolic location uses expressions such as office or elevator.
  • Localization techniques: Triangulation estimates a target’s location in three dimensions through lateration or angulation.Lateration uses distances to reference points, whereas angulation computes angles relative to reference points.

1) Lateration Techniques:

Lateration techniques estimate an object's position from signal timing or strength measurements relative to reference units. The section contrasts TOA, TDOA, RTOF, and RSS, including their indoor-environment limitations.

  • TOA: TOA estimates distance from one-way propagation time and requires measurements from at least three reference nodes in 2D.Precise synchronization and a transmission timestamp are required to verify direct signal travel.
  • Localization estimation: The estimated location can be obtained by minimizing a cost function formed for the measuring units.The state is represented as x = (x, y, t)^T, with v denoting the speed of light.
  • TDOA: TDOA determines relative position from arrival-time differences, placing the transmitter on hyperboloids of constant range difference.Intersecting two or more TDOA measurements estimates the target location in 2D.
  • RSS: RSS estimates distance from signal-strength attenuation, offering an alternative because TOA and TDOA suffer multipath effects indoors.Site-specific path-loss parameters, pre-measured RSS contours, multiple base stations, or fuzzy logic can improve accuracy.
  • RTOF: RTOF measures a signal's round-trip travel time to obtain range without TOA's stringent clock-synchronization requirement.A radar can measure the complete round trip when the target replies to the transmitted signal.

2) Angulation Technique:

Angulation, including Angle of Arrival, locates an entity by intersecting direction lines from known reference points. It can support 3D positioning without time synchronization but requires substantial hardware and accurate angle measurements.

  • Angle of Arrival: AOA determines position by intersecting pairs of angle-direction lines formed from base stations toward the moving target.In 2D, the method requires at least two known reference points and two measured angles.
  • Advantages: AOA can estimate a 3D position using a minimum of three measuring units without synchronization among them.This is an advantage over techniques that depend on synchronized timing.
  • Limitations: AOA requires complex, large hardware, and its accuracy degrades as the entity moves farther from the measuring units.Multipath and shadowing can impede accurate angle measurement indoors.
  • Proximity: Proximity algorithms infer symbolic relative position using a dense grid of known antennas and assign detection to the strongest signal when multiple antennas respond.The target is treated as co-located with the detecting antenna or, when several detect it, with the strongest-signal antenna.

V. MICRO-LOCATION ENABLED SERVICES

Micro-location and geofencing support context-aware services in IoT-equipped smart buildings, improving tenant assistance and enabling targeted interactions. The paper surveys current and envisioned applications across commerce, mobility, and building assistance.

  • Overview: Micro-location services are used in residential and enterprise settings to increase tenants' comfort and satisfaction, while poor integration reduces system efficiency.The section introduces existing geofencing and micro-location services and additional envisioned scenarios.
  • Targeted e-marketing: Geofencing and micro-location enable context-aware e-marketing, such as coupons for customers entering a shop.The paper identifies targeted advertising as an existing commercial use and potential source of income.
  • Existing services: Geofences can trigger targeted retail notifications, including discounts, prescription availability, sports-arena offers, and proactive commuter updates.These examples connect a user's entry into a point of interest with timely location-based information.
  • Targeted e-marketing: Targeted services remain in infancy and require better preference information to avoid flooding customers with irritating advertisements.The paper notes that excessive advertising may cause customers to unsubscribe.
  • Tenant assistance: Context-aware micro-location can help students find suitable library spaces and automatically adjust a manager's office environment when entering a company geofence.The described office response includes activating the computer and HVAC and setting temperature according to preference.

C. Energy Efficiency

Micro-location-enabled services are presented as tools for improving energy efficiency and supporting smart-building operations. Their effectiveness depends on coordinated systems, tenant context, accurate positioning, and unresolved implementation challenges.

  • Energy efficiency: Smart buildings pursue energy efficiency by coordinating systems to minimize wasted energy.The paper identifies energy efficiency as a driving force behind smart-building adoption.
  • Energy infrastructure: Energy-efficient solutions require demand-side management, micro-level energy storage, renewable sources, and consumption controllers using price signals.These capabilities are described as building and house requirements for efficient operation.
  • Geofencing example: A circular geofence can surround a smart building that advertises an electric charging facility to nearby electric vehicles.The figure illustrates a geofencing-based service associated with the building.
  • System of interaction: Connected appliances can interact and optimize resources by using the least possible energy while maintaining the tenant's desired comfort.A system of interaction supports communication among energy-consuming devices.
  • Micro-location role: Micro-location services improve energy efficiency by reducing energy waste and optimizing appliance and energy-device performance.Proper tenant assistance also requires subscription, position, and preference information.
  • Disaster management: Indoor shadowing, multipath, uncertainty about individuals' clinical conditions, and broader integration challenges constrain disaster-management applications.The paper presents crowdsourcing and context-aware services as potential components of disaster-management systems.
  • Accuracy requirement: Micro-location services require positioning accuracy finer than 1m, while UWB and BLE can provide accuracy as high as 10cm.The paper links this positioning requirement to the surveyed smart-building services.

A. Interoperability

Micro-location technologies differ in concepts, vendors, and protocols, creating interoperability barriers for IoT-equipped smart buildings. Standardization and tenant privacy protections are identified as necessary for coordinated, trusted services.

  • Different micro-location technologies lack interoperability despite serving similar location tasks.
  • Vendor-specific iBeacon SDKs create lock-in and can require end-to-end system updates when beacons are upgraded.
  • Closed or vendor-specific protocols prevent different beacon systems from communicating through a common standard.
  • Standardized protocols are needed so technologically different but task-similar systems can interoperate and work toward shared micro-location services.
  • Location disclosure requires tenant approval, making privacy protection and trust central to wider adoption.

1) Micro-location enabling devices:

Micro-location devices must balance accuracy, range, and energy consumption across beacons, user devices, UWB, and RFID. Energy use remains an open research issue, while filtering can improve indoor positioning accuracy.

  • Micro-location enabling devices:: Micro-location devices must be energy efficient because their consumption can hinder large-scale adoption.
  • Micro-location enabling devices:: iBeacon transmission power and interval can be reduced to save energy, but this trades performance for efficiency.
  • Micro-location enabling devices:: User-device energy optimization is important because battery technology has not kept pace with other technological improvements.
  • Micro-location enabling devices:: BLE devices consume less energy, and longer beacon intervals let user devices sleep for longer periods.
  • Micro-location enabling devices:: UWB offers higher bandwidth, lower power consumption, shorter range, and low cost than Wi-Fi, but still draws significant smartphone battery energy.
  • Micro-location enabling devices:: Passive RFID avoids battery use but has shorter range, whereas active RFID improves range through battery-powered transmission.
  • Micro-location enabling devices:: The effect of energy consumption on micro-location services has not been studied, leaving simplification without accuracy loss as an open problem.
  • Micro-location enabling devices:: Indoor positioning accuracy is limited by obstacles, while filtering techniques can improve beacon-based micro-location estimates.

E. Security

Security in IoT-equipped smart buildings is challenged by constrained devices, heterogeneous deployments, scalability, privacy risks, and cloud exposure. The paper calls for flexible, implementable security frameworks alongside continued research on micro-location services.

  • E. Security: Cost-efficient, power-constrained micro-location devices can be vulnerable to attacks and may expose entry points into smart-building systems.
  • E. Security: Conventional credentials may exceed the memory or processing capabilities of small, unmanned devices.
  • E. Security: Large smart-building deployments require common standards for zero-touch provisioning and must address service scalability across many endpoints.
  • E. Security: A flexible security framework should include authentication, authorization and access control, and network-enforced policy.
  • E. Security: Cloud-stored location information can be misused, while network attacks can manipulate or expose data and threaten user privacy.
  • E. Security: Traditional security protocols cannot guarantee protection for these services, which must remain reliable, fast, and implementable on energy-constrained devices.
  • E. Security: Micro-location services are presented as a route to greater tenant comfort and system efficiency through smarter use of user positioning.
  • E. Security: The paper surveys current technologies and services while identifying security, privacy, accuracy, and energy consumption as continuing research challenges.
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