IOT has been the hottest topic in the technology arena for a long time now. Even though the concept was introduced a while ago, only recently we have seen a surge in technology adoptions followed by many companies in their run up to bridge the gap between the digital and real worlds. In any of such implementations, one thing in common will be the adoption of an RF technology to facilitate easy data transfer. It is often a topic of debate among vendors that one RF technology is better than the other. As a matter of fact there are certain properties of one RF signal that helps it stand out from the others for a particular application. Let’s put forward the general idea about what are the technologies being offered by vendors in terms of properties, hardware, advantages & disadvantages at a vendor-neutral stand point.
Below table is a reference matrix for a quick evaluation of various aspects of each technology.
BLE(Bluetooth Low Energy) : Initially introduced as Bluetooth Smart, BLE is one of the most adapted technologies in order to facilitate connectivity. Unlike Bluetooth 2.0 EDR or Bluetooth 3.0 HS with higher data rate functionality, BLE(A subset of bluetooth specification 4.0) targets effective communication with devices that do not need streaming data or high data throughput. The BLE specification effectively imposes 2 types of devices: a dual mode device(eg. smart phone) which can support BLE in addition to the classic bluetooth protocol and a single mode device(beacon), which supports only BLE protocol.
Due to the widespread use of bluetooth transceivers in modern devices, majority of the enterprise devices are BLE ready. Therefore, the technology adoption and communication become seamless and cost effective. They deliver granular-level visibility for individual package delivery and asset management, as well as a more comprehensive end-to-end monitoring solution indoors, outdoors or in-transit.
BLE implementations usually have a single mode device called a beacon that continuously advertises low energy signals. Beacons are low-cost, low-powered transmitters equipped with Bluetooth Low Energy or BLE that can be used to deliver proximity-based, context-aware messages or perform location analytics. A beacon doesn’t really transmit content, it simply transmits a signal advertising) that lets a user’s phone or a BLE gateway figure out its proximity to the beacon. When a relevant app recognizes a beacon signal, a predefined ‘action’ is triggered via the app, to the user’s mobile device.
Even though a BLE solution can provide a lot of benefits in terms of functionality and ease of integration, there are certain challenges that need to be considered. Since the technology requires installation of battery powered beacons, the maintenance can become a tedious activity. Asthe location service with BLE highly relies on the RSSI of the RF signal, the accuracy will be between 1 – 3 meters. The cost of the beacon is higher than a regular passive RFID. However, a BLE project will be cost effective if deployed in a large premise with a sizeable number of beacons.
Pros & Cons of BLE
- Most of the smart devices are Bluetooth ready which enables easier BLE implementation
- Lower Energy utilization reduces battery consumption.
- Provides Granularity in visibility.
- Enables real time operation with low packet transfer.
- Maintenance of a lager beacon deployment is difficult.
- Location tracking can have a deviation of 1 – 3 meters from actual position.
- Need to have a large deployment to be cost effective.
- Additional receiver(Gateway) is required for applications like tracking.
WiFi is a technology that uses radio waves to provide network connectivity. A WiFi connection is established using a wireless adapter to create hotspots – areas in the vicinity of a wireless router that are connected to the network and allow users to access internet services. Once configured, WiFi provides wireless connectivity to your devices by emitting frequencies between 2.4GHz – 5GHz, based on the amount of data on the network.
Inside buildings, Wi-Fi is a good alternative to GPS, which is not available indoors. In most cases it is easy to install a Wi-Fi positioning system (WPS) as Wi-Fi access points already exist in many buildings. The advantage is that for say existing cash register systems, public hotspots and access points of shops or exhibitors can be used. The user doesn’t necessarily have to connect with the Wi-Fi, it is sufficient to be Wi-Fi enabled.
Pros & Cons of BLE
- No additional hardware required (Existing APs can be utilized)
- No additional power source required.
- Wifi is an essential requirement for all users ensuring more connected devices
- Ranges farther that BLE at an average of 100 – 250 meters
- Wifi data rates and through put is higher making it slower than BLE.
- Provides a zonal visibility than a granular approach.
- Defines the proximity of a connected device to a range of 5 – 15 meters.
RFID(Radio Frequency IDentification)
RFID systems involve an RFID tag(effectively a transponder) that sends data to reader. The average range of a passive RFID tag is 0.5 meters to 3 meters. Passive tags or transponders receive the energy to transmit their information (at frequencies between 866 MHz to 868 MHz) from the radiation field of the reader. Due to these reasons, Passive RFID is not a good option for location services. While using passive RFID, a reader needs to capture the data at a close proximity of the tag which is not ideal to identify the location and track items or people in real time. Passive RFID is best for asset tracking and keeping inventory that does not need a real-time monitoring of movement.
Unlike Passive RFID, Active RFID has a longer range and does not need a reader to intimate the tag to send signal. Active RFID, as the name suggests stays active using a battery powered chip. Therefore, data will be available in real time for a reader to gather and update a back-end system for location services and tracking. So-called active transponders, which have their own power supply, theoretically even reach transmitter ranges in the kilometer range. However, the unit price of the transponders increases considerably. This also makes the transponder considerably larger.
RFID alone is only partially or rarely suitable for the implementation of location-based services. A major disadvantage is the rather small range, but above all, the fact that although it is possible to identify whether an RFID tag is in reader A or B, the path in between cannot be detected. However, it is precisely this information that is necessary for the optimization of logistical processes. Therefore, passive RFID by itself in not best suited for flexible positioning or even indoor navigation. However, combining passive RFID with beacon technology is optimal for warehousing processes and eliminates most of the disadvantages.
Pros & Cons of BLE
- Passive tags are cost effective.
- Passive RFID Tags do not require a power source.
- Active tags are costly and bigger is size.
- Passive RFID cannot provide a real time update of assets.
- Not ideal for people tracking due to interference.
- Read range is less – about 0.5 – 3.0 meters.
UWB(Ultra Wide Band)
The UWB spectrum was opened for commercial use in 2005 by the FCC for pulse-based transmission in the 3.1 to 10.6 GHz frequency range. Applications target sensor data collection, precision locating and tracking applications which is the focus here.
With UWB, we measure the time it takes for the signal to travel from transmitter to receiver in order to calculate the distance in centimeters. This method gives much better distance information than determining distance based on signal strength with beacons.
The apps can receive precise location data (less than 20 cm deviation) and location updates can be delivered every 100 ms if necessary. A user will carry a small UWB tag to monitor their exact location. The tag is equipped with a UWB transmitter and can feed of the phone’s USB port or a coin-size battery with a 1 year life. It sends out a ping signal via UWB for every location update and is also equipped with an acceleration-meter which will keep it at rest if it is not moving.
UWB involves the use of a Tag similar to a BLE beacon and an anchor equivalent to a BLE Gateway. Though UWB can be used to track the location to a more precise level than the BLE, additional hardware need to be attached to the smart phone devices in case of an application centric architecture. Since the Smart phones are not pre-equipped with UWB receiver, the additional hardware will help the application in accessing Tag information directly.
Pros & Cons of BLE
- UWB can provide centimeter level accuracy
- Can cover a larger area than other RF technologies.
- Lower interference from other signals.
- Higher cost than other technologies
- Smart device are not UWB ready.
- Additional hardware required for direct communication with smart devices in an application-centric architecture.