System Description

TD 93025US
9 May 2019 / Ver. I 97
System Description
teleCARE IP
9.15 RSSI-based Location Determination
RSSI (Received Signal Strength Indication) is a measure of strength of a received radio
frequency signal. RSSI-based location determination functionality enables you to use the
RSSI value received by the teleCARE IP base stations (NIRC3 + NIRX), wireless gateways
(NIRC3 + NUREP) and wireless repeaters (NUREP) to roughly determine the location of a
wireless device. The following equipment is required for RSSI-based location determination:
• - Base Station(s) - The “base station” referred to in this section consist of the room controller -
NIRC3 with a piggyback mounted transceiver module - NIRX.
AND / OR
- Wireless gateway(s) - The “wireless gateway” referred to in this section consist of the room
controller - NIRC3 with a wireless repeater (NUREP) connected via USB.
- Wireless repeaters (NUREP) as part of the wireless infrastructure using wireless gateways.
• LF Beacons - If required, LF beacons can be installed at strategic locations to further increase the
accuracy of the RSSI-based location determination functionality.
• NITX with LF - Wireless mobile transceiver module that supports LF.
• NIFX with LF - Wireless fixed transceiver module that supports LF.
Although an NIFX is a fixed device, it can become mobile when mounted to a movable bed or
wheelchair for example. Therefore the NIFX comes included with an LF receiver and RF transceiver
in order to support RSSI location determination functionality.
The aim is that RSSI does not require changes in the physical system setup, however the
location of the room controllers (NIRC3) that function as a base station or wireless gateway
and the wireless repeaters have to be selected carefully. The location of the receiver with
the strongest RSSI signal will be used for messaging, linking and forwarding.
Be aware that RSSI-based location determination will only give a rough estimation of the
location of the wireless device. The accuracy depends on the placement of receivers that
cover the detection area. The received RSSI signal strength will also be influenced by other
factors, such as the building structure / materials, orientation of the receiver and the
orientation of wireless devices.
The example below shows the layout of a site with only one floor and six receivers.
Figure 80. Location determination using RSSI