UWB, WiFi case study for a large hospital
November 2014 OpenRTLS and a dutch system integrator completed a case study on a medium scale RTLS (real time location system) deployment of 25.000 tags in a large hospital in The Netherlands. All relevant cost within a 9 year period are taking into account. Tags are required to have a button, to be lightweight and have a multi year battery lifespan. WiFi based location system in hospitals are common in the USA, in Europe active RFID gained significant traction among technical and operational directors. A comparison with UWB is provided as a case study.
Cost saving goal hospital: 350.000eu/yr
The goal of the RTLS system is to reduce operational cost of the hospital. Estimated savings amount to 300 to 400.000 euro annually for phase 1. Main cost reductions are lower labor cost in searching & inventory counting. Lower total amount of devices needed to deliver same level of service to the patients, insight in asset utilization and reduction of theft and loss.
Items to be tagged are mainly: Infusion Pumps, Ventilators, Pulse Oximeters, Stretchers, Telemetry Transmitters and wheel chairs.
Next phase 2: implementation for patient, staff and visitor tracking, secured access control on automatic door opening, passive security radar and the energy management capabilities of the special type NeYo anchors.
Initial one-time investment: €2.30 million
- Aeroscout site license multimodules: 200k
- 625 extra cisco 2700 series access points: 300k (1)
- Installation cost extra access points:50k
- 25.000 tags T3: 1500k
- Labor: Fingerprinting the buildings: 20k(4)
Annual cost aeroscout: €115.000 /year
- License upgrade & maintenance fee: 40k
- Energy consumption per year: 12k
- Battery (4eu) replacement every 3 year, 5min update rate: 30k (2)
- Labor: retrieving devices & replace battery (6min): 28k /year
- Labor: re-fingerprinting: 5k/year
(1) recommended amount of WiFi AP by cisco/aeroscout
(2) Thionyl Chloride Battery are highly toxic
Initial one-time investment: €1.15 million
- RTLS 4200 power socket anchors + 245 anchors: 330k
- Installation cost RTLS infrastructure: 35k (3)
- 25.000 tags C1: 750k
- Fingerprinting of the building: not a requisite with UWB.
Annual cost openRTLS: €4.000 /year
- License upgrade maintenance fee: 0
- Energy consumption per year: 4k
- No-Battery replacement within 10+ years on 1 minute update
- No-retrieving devices & battery replacement required
(3) Mains outlet socket installation of UWB anchor takes 4 minutes average
(4) Steven C.H. Hoi and Wray Buntine. Tokyo university 2012
UWB triples the value for money to WiFi
The key metrics on localisation are:
Cost (3x): Total cost after 9 years. WiFi €3,37 million UWB €1.17 million for UWB. 3 times better value for money compared to WiFi
Accuracy (10x): WiFi 3meter open space to 9 meter average inaccuracy for patient quarters (70% reliability level) in hospitals. UWB 0,3m (95% of the time) for any environment. 10 times better performance.
Power consumption (3x): WiFi Access Points consume 15 times more energy. For 1250 WiFi AP, 625 AP are needed in addition to enable localisation, Total energy cost 12.000 euro/year. UWB although higher number of anchors, power consumption cost are 4.000 euro (3 times better)
Battery life (50..100x): openRTLS Tag C1 can provide location updates 50 to 100 times more on the same battery charge compared to WiFi aeroscout Tag T3. Here update rate was set at once every minute for UWB and once every 5 min for WiFi aeroscout. The UWB tags will last for more then 10 years.
Tag density (5x): because of fast update rates high tag densities are possible. UWB can handle 240.000 tags per channel at 5 min update rate. With 5 available channels the total maximum is well over 1 million tags even at 1 minute update rate.
Range (3x): With a special, still cost effective, antenna like the horn antenna indoor openspace range can be well over 200 meter while maintaining accuracy.
Network traffic (perfect) : UWB does not interfere with WiFi bands thus keeping WiFi open for other communication needs
Extra benefits (nice to have) : With UWB other application for the hospital can now also be accomplished. For example secured automatic door opening, indoor passive radar for nightly detection of person's without a badge (to be launched in 2015). Energy management via the mains-wallsocket mounted neyo anchors, 3D virtual games for children, crowd and evacuation control.