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Indoor Location Solutions: A Comparison

As businesses and organisations continue to expand, the demand for indoor location technologies also grows. These technologies are crucial for locating people or objects in areas where GPS and other satellite technologies lack precision or fail entirely. To meet the requirements of accuracy, cost-effectiveness, and quick development time, several indoor location technologies have been introduced. These technologies play a crucial role in various domains, including

  • asset tracking,
  • customer analytics,
  • way-finding
  • Warehouse Management
  • Retail Analytics
  • Healthcare, and
  • Proximity Marketing.

In this blog, we will compare four popular indoor localisation technologies:

  • UWB (Ultra-Wideband),
  • RSSI(Received Signal Strength Indicator)-based on Bluetooth,
  • AoA(Angle of Arrival) or AoD (Angle of Departure) based on BLE(Bluetooth Low Energy), and
  • RFID(Radio-Frequency Identification).

By comparing these technologies across key parameters, we aim to help businesses determine which technology aligns best with their goals.

Why Indoor Location?

In today’s interconnected world, there is a growing need to locate and track assets within indoor environments. Indoor location identification carries value across countless industries and use cases. Accurate indoor location can enhance operational efficiency, improve customer experiences, and enable better decision-making.

How the Bluetooth RSSI Works?

RSSI (Received Signal Strength Indication) works by measuring the power level of a received radio signal at the receiver. It quantifies the strength of the signal, indicating how strong or weak the signal is when it reaches the receiver. By comparing the received signal strength to a reference signal strength, RSSI provides an indication of the signal quality and can be used to estimate the distance between the transmitter and receiver. By combining the RSSI measurements from multiple locators and utilizing techniques such as trilateration or multilateration, the position of the tag can be determined. However, it’s important to note that RSSI-based distance estimation may not be as precise as other methods and can be influenced by various factors, which should be considered when using it for accurate indoor location tracking.

How Angle of Arrival (AoA) or Angle of Departure (AoD) Based BLE works?

In early 2019, the Bluetooth Alliance SIG (Special Interest Group) introduced the Direction Finding in the Bluetooth standard specification 5.1, pushing Bluetooth positioning technology has also entered the field of high-precision positioning.

AoA and AoD are techniques used in Bluetooth Low Energy (BLE) to determine the direction of a signal. AoA works by utilizing multiple antennas on the receiver side to measure the phase difference between the received signals. By comparing phase differences and distance between antennas in array , the angle at which the signal is arriving can be calculated.

Similarly AoD, multiple antennas on the transmitter side are used to transmit signals with a known phase difference. By measuring the phase difference of the received signals, the angle at which the signal is departing can be estimated. These techniques enable accurate localization and tracking in BLE applications, providing valuable information for various use cases such as indoor navigation and proximity detection.

Difference between AoA and AoD:

High-precision Bluetooth positioning technology is divided into AoA angle of arrival and AoD Angle of Departure according to the different uplink and downlink modes of the positioned terminal. However, whether it is AoA or AoD, the basic principle of angle detection is the same.

The AoA uses a single antenna to transmit a direction-finding signal, and the device at the receiving end has a built-in antenna array. When the signal passes through, there will be a phase difference due to the different distances received in the array, and then the relative signal direction is calculated.

AoD The departure angle rule is the opposite. The signal is sent by a device with an antenna array in a fixed position and transmitted to a terminal with a single antenna. The terminal can calculate the direction of the outgoing wave based on the received signal, and then locate it. The positioning characteristics of the AoA method and the AoD method at the transmitter and receiver are compared.

How Does RFID Work?

RFID works by employing an RFID transponder (or tag) and a reader. The RFID transponder is comprised of a microchip that holds information to identify an object, product, or person and an antenna for transmitting this data to the reader.

The antenna transmits the data to a reader that converts the radio waves to usable information. Unlike bar code and magnetic stripe technology, RFID transponders can be read anywhere within the magnetic field sent out by the reader. Radio waves can travel and be read through many non-metallic objects. Depending on the power of the reader, an RFID antenna can be read from direct contact up to 20 feet.

In passive systems, which are the most common, an RFID reader transmits an energy field that “wakes up” the tag and provides the power for the tag to respond to the reader.

Passive tags do not have a battery and draw their power from the reader. The reader sends out electromagnetic waves that induce a current in the tags antenna. Since these tags obtain their power from the reader, they generally have shorter read ranges and are in a defined reader zone. Passive RFID is relatively inexpensive and found in many daily surroundings. They can be very small with size dependent on the type of tag antenna.

In active systems, a battery in the tag is used to The effective operating range of the tag and to support additional features over passive tags, such as temperature sensing. Data collected from tags is then passed through communication interfaces (cable or wireless) to host computer systems in the same manner that data scanned from barcode labels is captured and passed to computer systems for interpretation, storage, and action.

Active RFID tags work independently, so the tags themselves can transmit and receive data. As they generally transmit data over a longer distance they are physically larger and more expensive than passive tags and are operational as long as the battery is functional. Passive RFID is an optimum combination of benefit and costs and uses a frequency that fits most customer applications.

What Is the Frequency Range of RFID?

There are several radio frequencies in use.

  • Low Frequency (LF): 125kHz
  • High Frequency (HF): 13.56 MHz
  • Very High Frequency (VHF): 433 MHz
  • Ultra-High Frequency (UHF): 860 – 960 MHz
  • Microwave Frequency: 2.4 GHz

How UWB (Ultra-Wideband) Works:

Ultra-Wideband (UWB) technology works by transmitting extremely short and low-power pulses of radio waves across a wide frequency range. These pulses are spread out over a large bandwidth, enabling higher precision and accuracy in terms of spatial and temporal resolution. UWB signals are transmitted using a wide spectrum of frequencies, rather than a single narrow frequency, which helps in achieving accurate positioning and distance measurements.

UWB operates by utilising the time of flight (ToF) principle. When a UWB transmitter sends out a pulse, it travels at the speed of light and encounters various objects, such as walls or obstacles. Some of the pulses are reflected back and picked up by a UWB receiver. By measuring the time, it takes for the pulse to travel to the object and back, the system can calculate the distance between the transmitter and receiver with high precision.

UWB technology carries significant advantages in terms of its ability to penetrate walls and other obstacles, its high resistance to interference, and its capability to operate in dense environments without severe signal degradation. It has applications in various fields, including indoor positioning, asset tracking, contactless payments, and IoT device connectivity, where accurate positioning and reliable data transmission are crucial.

Use Cases:

Before diving into the comparison, let’s explore some common use cases for indoor location technologies:

  1. Asset tracking & management: Finding & tracking assets makes using IoT greatly useful for keeping track of assets, optimising supply chains, ensuring efficient facilities management, and potentially improving the productivity of a company’s workforce.
  2. Warehouse Management: Distribution centers in the retail industry and production will also benefit from the location of their employees, goods, and machinery to improve the effectiveness and accuracy of workflow.
  3. Retail Analytics: Understanding the movement of visitors or customers to develop advertising and product localisation strategies and minimise  unnecessary disruptions in those high traffic areas.
  4. Healthcare: By location tracking employees and furniture, hospitals can enhance patient experience and optimise  their customer service.
  5. Proximity Marketing: By detecting the presence of customers within specific areas, businesses can deliver targeted marketing messages and promotions in real-time.
  6. Way-finding: Navigation within large indoor spaces, like airports or shopping malls, can be made more seamless and efficient by providing step-by-step directions to desired destinations.

Comparison:

Conclusion:

Each of the mentioned indoor localisation technologies possesses its own strengths and weaknesses. Choosing the appropriate one means reviewing the allocated budget, the context of work, requisite accuracy, timeframes, and operation requirements.

UWB and AoA-based BLE offer high accuracy but at a higher cost and longer development time. RSSI-based Bluetooth strikes a balance between accuracy, cost, and development time. On the other hand, RFID has low technical complexity and infrastructure requirements but sacrifices accuracy.

The choice of technology ultimately depends on your specific use case, budget, and timeline. For precise asset tracking applications where high accuracy is crucial, UWB or AoA-based BLE may be the optimal choice. For more cost-effective and quicker deployment in certain situations, RSSI-based Bluetooth or RFID might be more suitable.

Why Spicules?

  • Extensive expertise in Indoor location technique development and deployment
  • Custom solutions tailored to specific business requirements
  • High priority on quality and accuracy of solutions
  • Cost-effective and efficient system implementation
  • Successfully delivered projects in various industries
  • Qualified and experienced professionals capable of handling complex projects
  • Active communication with clients to ensure satisfaction and understanding throughout the process

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Indoor localisation technologies play a pivotal role in revolutionising various industries and improving efficiency in indoor environments. By understanding the unique features and trade-offs among UWB, RSSI-based Bluetooth, AoA-based BLE, and RFID, businesses can make informed decisions that align with their goals and requirements.

If you have any questions or need further assistance in choosing the right technology for your indoor localisation needs, feel free to reach out to us. We are happy to provide tailored recommendations to your requirements.