Logistics / Warehousing / Asset Tracking
UWB asset tracker: Ultra-wideband RTLS with TDoA and two-way ranging for warehouses
For a Bangalore warehouse-technology company we built an ultra-wideband (UWB) RTLS with custom UWB modules, TDoA and two-way ranging, and WMS integration. Completed and field-trialled in warehouses by early 2025.
What we did: We designed custom UWB modules and their low-power RTOS firmware, implemented Time Difference of Arrival (TDoA) and Two-Way Ranging (TWR) localisation on a clock-synchronised anchor network, added a mesh backhaul between anchors for large sites and edge processing for low-latency updates, and integrated live positions with the client's warehouse management system (WMS).
Warehouse-technology company, Bangalore, India6 monthsTeam of 6
Status: Completed; field-trialled in warehouses (case study first published January 2025)
Published Last reviewed:
Illustrative imageThe challenge
The client needed to track assets inside warehouses with high precision and without GPS, which does not work indoors. Positions had to update fast enough for dynamic warehouse operations, the system had to scale to large sites, feed the client's warehouse management system in real time, and be cheap enough to mass-produce in India.
GPS-denied environment
Inside a warehouse there is no usable GPS signal, so positioning must come from a local radio system.
Low-latency positioning
Assets move constantly; stale positions are of little use to warehouse operations.
Scale
Large warehouses need many tags and anchors to work as one system without the network becoming the bottleneck.
Cost for mass production
The hardware had to be cost-optimised so it could be manufactured in volume in India.
Impact figures describe the situation before the project, as the client reported it to us; we did not measure them.
Our solution
We designed a UWB real-time location system (RTLS). UWB measures radio time of flight very precisely, so positions come from timing rather than signal strength. We used two methods: Two-Way Ranging (TWR), where a tag and an anchor exchange messages to measure the distance between them, and Time Difference of Arrival (TDoA), where fixed anchors timestamp one tag message and the position is solved from the differences. TDoA only works if the anchors share a common time base, so the anchor network carries clock synchronisation. The tags do not mesh; a mesh backhaul between the anchors scales the system across large sites, and processing at the edge keeps updates fast and reduces dependence on the cloud.
System architecture
UWB modules, a localisation engine, and a live feed into the WMS.
UWB hardware
- Custom-designed UWB modules
- Low-power firmware for extended tracker battery life
- RTOS-based firmware
Localisation
- Two-Way Ranging (TWR) for tag-to-anchor distance
- Time Difference of Arrival (TDoA) for position solving, on clock-synchronised anchors
- Edge processing for low-latency updates
Network and integration
- Mesh backhaul between anchors for large warehouse deployments
- API integration with the client's WMS
- Real-time analytics from live positions
Key design points
- Radio
- Ultra-wideband (UWB)
- Methods
- TDoA + Two-Way Ranging
- Firmware
- RTOS, low-power
- Network
- Mesh backhaul between anchors (tags do not mesh)
- Processing
- At the edge, low latency
- Integration
- API to the client's WMS
What we delivered
- Custom UWB module design
- TDoA and TWR localisation algorithms
- Low-power RTOS firmware for trackers
- Anchor mesh backhaul for scalable deployments
- Edge processing for low-latency position updates
- WMS API integration for real-time analytics
- Cost-optimised design for mass production
Outcome
The system completed field trials in warehouses and was integrated with the client's WMS. We do not publish a positioning-accuracy figure: accuracy depends on anchor layout, anchor clock synchronisation and site conditions, and no test protocol for it is on record. Nor do we publish an operational-saving figure, because no measurement of one is on record.
How to read the labels: Client-reported baseline = the client's own figure for the situation before the project; we did not measure it. Figures without a label are specifications or project scope.
Field trials
Completed
Real-time positioning in warehouse conditions
WMS integration
Live
Positions feed the client's warehouse management system
Design duration
6 months
Team of 6
Technologies used
- Ultra-wideband (UWB)
- TDoA
- Two-Way Ranging (TWR)
- RTLS
- RTOS
- Anchor clock synchronisation
- Mesh backhaul
- Edge processing
- WMS integration
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