Bluetooth Low Energy (BLE) is a part of the Bluetooth wireless standard optimized for low power. It is commonly used for small or intermittent data transfers from devices that need to run for a long time on a small battery. It operates in the unlicensed 2.4 GHz band, like classic Bluetooth and some Wi-Fi, but stays asleep most of the time and wakes briefly to transmit. That makes it the usual choice for asset tags, beacons, sensors, wearables and smart locks, and one of the main technologies behind indoor location services. Nearly all current smartphones support it, which means phones can act as BLE readers too.
At a glance
- BLE is optimized for low power and commonly used for small or intermittent transfers; LE Audio adds audio streaming, while bulk file transfer remains a poor fit.
- Typical uses are asset tags, beacons, sensors, wearables, badges and device setup.
- Location accuracy ranges from room or zone level to a few meters, depending on method and receiver density.
- Receivers can be dedicated gateways, Wi-Fi access points with Bluetooth radios, or smartphones.
- It uses unlicensed spectrum, but devices still need regulatory approval in each country where they are sold or used.
What problem it solves
Many building and operations problems need a small amount of data from a large number of devices: where is this wheelchair, is this freezer warm, is this room occupied, which entrance did this badge use. Running cables to each one is impractical, cellular is often overkill, and Wi-Fi uses too much power for a coin-cell device. BLE fills that gap with cheap radios that can run for months or years on a small battery, depending on how often they transmit.
Because smartphones already have BLE, it also lets organizations build phone-based experiences, such as wayfinding, check-in, mobile keys and proximity alerts, without issuing new hardware to users.
How it works
Advertising and connections. A BLE device can broadcast short “advertising” packets that any nearby receiver can hear, or form a connection with one device to exchange data. Beacons and many asset tags only advertise; sensors and wearables often connect.
Beacons. A beacon broadcasts an identifier at a set interval. A phone app or gateway that hears it can infer it is near that beacon. Several beacon formats exist, and most enterprise platforms support the common ones.
Location. The simplest method uses received signal strength from several receivers to estimate which zone a tag is in. Newer Bluetooth versions add direction-finding features that can improve accuracy where tags and receivers support them. Walls, people and metal affect results, so careful layout and calibration matter.
Infrastructure. Receivers forward what they hear to a platform over Ethernet, Wi-Fi or cellular. Many enterprise Wi-Fi access points include a BLE radio, so location and sensor projects can sometimes reuse the Wi-Fi network rather than add separate gateways.
Audio. LE Audio, a newer addition to the standard, carries audio streams over BLE on devices that support it, such as some earbuds and hearing aids. Large file transfers are still better handled by Wi-Fi or a wired connection.
Mesh. Bluetooth also has a mesh networking option, used in some lighting and building control systems to relay messages across many devices.
BLE is one of several connectivity options in an Internet of Things (IoT) program. Our Indoor Location Services solution page covers how to compare BLE, Wi-Fi and other location approaches.
When it matters for buyers
- Finding mobile equipment indoors. Hospitals, warehouses and campuses use BLE tags for asset tracking.
- Wi-Fi refresh. Choosing access points with BLE radios now can make later location projects cheaper.
- Workplace occupancy and wayfinding. Badges, beacons and phone apps can show how space is used.
- Staff safety. Some panic-button and lone-worker systems use BLE badges to report location.
- Battery maintenance planning. Hundreds of tags mean hundreds of batteries; plan the replacement cycle.
Questions to ask vendors
- What location accuracy have you achieved in buildings like ours, and how was it measured?
- Can we use BLE radios in our existing or planned access points, or do we need separate gateways?
- What is the battery life of each tag at our chosen broadcast interval, and how are low batteries reported?
- Which beacon formats and tag types does your platform support, and can we use other vendors’ tags?
- How are firmware updates delivered to tags and gateways?
- Are your devices approved for use in each country where we will deploy them?
- What data do the tags broadcast, and who can read it?
How it differs from RFID
BLE and radio-frequency identification (RFID) both identify tagged items by radio. A passive RFID tag has no battery and only responds when a reader energizes it, so it suits cheap, high-volume tagging and checkpoint reads at doors or docks. A BLE tag has a battery and broadcasts on its own, so a network of receivers can follow it continuously, at a higher cost per tag. Projects often choose RFID for counting many items and BLE for locating fewer, higher-value ones.