Real Time Location Systems (RTLS)

Real Time Location SystemsAutomatic Identification and Tracking

© Jeffrey Dungen 2016

Purpose


Is RTLS beneficial for my application?

What choices do I have among RTLS?

How do the different RTLS work?

What should I reasonably expect?

My Background


Computer Engineer

RTLS, Geolocation & IoT startups since 2004

Applications from baggage to bike races...

DISCLOSUREI’m currently co-founder and CEO of reelyActive, an IoT/RTLS/M2M startup

Motivation


Dots on a Map


Is this what I expect?

Is this what I need?

Is this even what James Bond needs?

He/She/It isexactly here

RTLS for Humans


“The nearest IV pump is in room 123A”➔ Can the nurse find room 123A?➔ Can the nurse find an IV pump in a room?

How should your RTLS effectivelyassist humans?

RTLS for Computers


“RFID and sensor technology enable computers to observe, identify and understand the world—without the limitations of human-entered data.” — Kevin Ashton

How do computers understand identification & location?

Tech-First Approach


1. What is technically feasible/appropriate?

2. Can my problem technically be solved with RTLS?

3. How do I deliver a solution?

In my experience, this is currently the approach which most reliably leads to real solutions. Of course, I’m an engineer...

Technology


A Typical RTLS


Middleware

Sensor Sensor Sensor

Tag TagTag Tag TagTag Tag TagTag Mobile

FixedInfrastructure

HostedOn-site

Identification


Sensor

Tag

Passive RFID

Sensor

Tag

Active RFID

UHF

Infrared*SHFUHFUltrasound*

Energy sourcedfrom sensor

Energy sourcedfrom tag

*Not RF*Generalisation

10m*

Frequency Band


TagSensor Sensor

Water Wall

Absorption Reflection2.45GHz is used by WiFi,

Bluetooth and to heat food...Higher frequencies

reflect more → Multipath

Narrow vs. Ultra-wide


Tran

smis

sion

Du

ratio

n

Bandwidth

Narrowband

Ultra-wideband(UWB)

UWB transmissions are so short, they overcome reflections that affect the direct signal path.

Narrowband suffers what is called “multipath fading”.

RSSI


Received Signal Strength Indication➔ Estimate distance to tag based on signal strength➔ Ubiquitous sensor support➔ Significantly affected by absorption and reflection

Tag Sensor

Distance

AoA


Angle of Arrival➔ Estimate angle to tag based on phase shift on antennae➔ Requires multiple antennae per sensor➔ May require specific tag transmission sequence

Tag

Sensor

Angle

TDoA


Time (Difference) of Arrival➔ Estimate (relative) distance to tag based on arrival time➔ Requires multiple time-synchronised sensors➔ May require significant computing in middleware

Tag SensorSensor

t1 t2t2 - t1 = 10ns = Δ10ft

Fingerprinting


Leverage what you actually get➔ Calibrate based on actual sensor values (RSSI, etc.)➔ Granularity based on number of points observed➔ Changes in environment strongly impact results!!!

Sensor ARSSI

A = 150B = 100

RSSIA = 120B = 130

RSSIA = 110B = 160

Sensor B

Zone 1 Zone 2 Zone 3

Tech Summary


1. Active RFID and UHF Passive RFID support RTLS

2. Frequency and environment affect performance

3. Various location techniques with tradeoffs

Configurations


Checkpoint


Sensors detect tags only through checkpoints.

What if a tag enters/leaves via another passage?

Detect passage through here

Visibility

Detect presence throughout

Sensors detect tags throughout the facility.Coverage overlaps.

Can coverage extend too far?


Zone Location


Tags are located to the nearest zone.

Zone definitions must take into account the technology and sensor placement.

The tag is in this zone

Precise Location


Tags are located to precise coordinates.

Requires AoA or TDoA for the precision to meet reasonable

expectations.

The tag is exactly here

Config Summary


1. Checkpoints only? Or visibility throughout?

2. Zone location good enough? Precision required?

3. A combination of all of these may be ideal!

Practicalities


Tags


Options limited by budget and config.➔ Passive may be only cost-effective high-volume option!➔ Active RFID performance vs. battery life➔ Proprietary Active RFID performance vs. vendor lock-in➔ Flexibility of Bluetooth/WiFi BYOD vs. performance➔ Radio compliance for the target geography?

Sensors


Sensors need power & connectivity➔ PoE offers both on a single cable➔ Possible to get cable drops to the optimal locations?➔ WiFi/Mesh backhaul offers convenience over reliability➔ Is there a mains outlet at each optimal location?➔ Intentional or unintentional tampering?

Middleware


Last but definitely not least!➔ Proprietary or open source?➔ Vendor lock-in or alternatives?➔ Who maintains and operates?➔ Runs on-site and/or in the cloud?➔ Total cost of ownership?

Practicalities Summary


1. Tag selection may dictate the deployment!

2. Can I deploy the sensors as my needs dictate?

3. After all that, is there a middleware that fits the bill?

Examples


Retail Inventory


Back Store

Store(Visibility)

Receiving

Fitting Rooms

➔ Every article of clothing has UHF Passive RFID tag

➔ Visibility coverage in store ensures articles on display

➔ Fitting rooms zone location (requires radio shielding)

➔ Various middleware options

Hospital Staff & Equipment


Room(Zone)

➔ Every equipment has an integrated BLE tag

➔ Staff use mobile app (BLE)➔ AoA sensors for precision

tracking in Triage Ward➔ Cost-effective BLE sensors

for visibility & room zones➔ Bespoke middleware

Room(Zone)Room(Zone)

Room(Zone)Room(Zone)Room(Zone)

Triage(Precision)

Courtyard(Visibility)

WIP Tracking


Machine➔ Every employee has Active

RFID tag➔ Every WIP job clipboard has

Active RFID tag➔ Every machine has sensor➔ Open source middleware

Machine

Machine

Who’s applying which processto which job right now?

Examples Summary


1. There’s no “one-size-fits-all” solution!

2. Each requires system integration and at least some custom application development.

3. None of these required “dots on a map”!

Conclusions


Review of Purpose


Is RTLS beneficial for my application?

What choices do I have among RTLS?

How do the different RTLS work?

What should I reasonably expect?

Managing Expectations


It’ll likely take longer than you think, especially if process or behavioural changes are required!

BUT, a well-implemented RTLS will create efficiencies, streamline operations and provide a sustainable competitive advantage.

Thanks!
