F R A U N H O F E R I N S T I T U T E F O R P H O T O N I C M I C R O S Y S T E M S I P M S

Li-Fi − Optical Wireless Communication

Light as a Transmission Medium

Using light as a communication tool, for example in beacons

and lighthouses, has a long tradition in the history of mankind.

With a speed of approximately 300,000 km / s, light is the fast-

est known transmission medium. Technologically, everyone is

aware of optical signals used in the television remote control.

Even when radiation is emitted in infrared (IR), outside our vis-

ible spectrum, the transmission of data is based on the same

physical laws as those for the so-called visual light communica-

tion (VLC) using visible light.

So far, optical wireless communication has prevailed above all

only in special applications, with radio transmission technol-

ogies dominating the broader market of wireless data com-

munication. Due to the ever-growing amount of data to be

transmitted, radio-based wireless communication is increas-

ingly reaching its limits. In addition to the limited bandwidth

availability of radio systems, the so-called “Frequency Crunch”

problem, implementation costs are growing exponentially with

increasing transmission frequencies.

Therefore, optical wireless communication known as Li-Fi

(Light  Fidelity) is experiencing a renaissance due especially to

high data rates, relatively low production costs and the possibil-

ity to communicate in real time. Hence, light as a transmission

medium will, in the next years, play an increasingly important

role in both the industrial as well as in the consumer sectors.

The advantages of Li-Fi technology can be summarized in two

simple words:

Fast Low latency means real time capability

Accessible No cables means more flexibility

Secure Line-of-Sight means hard to hack

T iny Small module sizes are possible

Low-cost Low energy and production costs

Interference-free No RF interferences

G lobal No spectrum license fees

H igh-speed 10 × faster than other wireless solutions

T imely Up-to-date technology

Li-Fi − Optical Wireless Communication

Optical Wireless Data Transfer over

a Distance of Several Meters.

Li-Fi GigaDock

Our optical docking station addresses application scenarios

with ranges of a few centimeters. Data speeds of 12.5 Gbps are

now already realizable, still unachievable for radio connections.

The future will bring transmission speeds of over 100 Gbps.

Through narrow restrictions of the data connection with re-

gards to reach and field-of-view, up to 97% of the transmission

capacity can be utilized for user data.

In addition to a high net data rate and real-time capability, se-

curity plays a major role in this application scenario. Eavesdrop-

ping on communications is practically impossible and thereby

just as private as a direct access by means of a plug or cable

connection. In contrast, however, no open contacts exist. The

system remains fully closed on every side of communication.

Fraunhofer IPMS develops and manufactures transceivers for Li-

Fi docking applications with dimensions of down to 2 mm edge

length. A wireless energy supply is also possible at this distance.

Li-Fi Hotspot

The Li-Fi-Hotspot developed at Fraunhofer IPMS allows for the

installation of a private, high-speed network without imposing

cables.

The system offers high data rates of up to 1 Gbps, robustness,

low energy consumption, data security as well as networking

capability over a distance of up to 30 meters and its small size

is easily aligned and inexpensive to install.

The data exchange is limited to a defined area and therefore

does not interfere with other Hotspots nearby, making it possi-

ble to use the full bandwidth of each Li-Fi link.

In addition to Li-Fi-broadcasting modules sending data in one

direction, technology developed at Fraunhofer IPMS offers the

possibility of a real-time capable and bi-directional, “full du-

plex” communication.

Cable Replacement in Industrial Applications

With more and more sensors, machines and control units com-

municating with each other, industrial equipment is becoming

increasingly complex. Evolving requirements have also resulted

in increased demands to find substitutes for the prevailing wire-

bound fieldbus systems. Wireless systems offer better reliabili-

ty and security than expensive special cables or slip rings that

are prone to wear and tear, particularly in movable or moving

equipment.

Due to low latency, a Li-Fi communication channel is very well

suited for machine-to-machine interaction. It is therefore possi-

ble to synchronize sensor and actuator data and thus avoid col-

lisions or coordinate complex interactions between robot arms

or different subsystems.

Li-Fi solutions developed at Fraunhofer IPMS also allow the

expansion of existing infrastructure free of costly installation

through a an independent communication channel. This is es-

pecially beneficial in areas where conventional technologies are

Wireless Energy and High Speed

Data Transmission.

already in use by other applications or the use of radio systems

is impossible due to strong electromagnetic interactions.

The electrical interface communication for the Li-Fi module can

be individually adapted to the given requirements of an already

existing communication network, like Ethernet, Gigabit Ether-

net, RS422, RS232 CAN or Profinet. The modules are designed

to work in a plug-and-play manner without installation of ad-

ditional software.

Security

One of the main handicaps of optical wireless data transmis-

sion is the necessary line of sight. However, this constraint is

not only disadvantageous. Data can only be accessed by the

direct introduction of a receiver in the transmission channel.

Such an intrusion would, with high probability, be noticed al-

lowing for a swift response to such an event. Therefore, Li-Fi

communication combines the flexibility of wireless communi-

cation technology with the security of traditional cable-wired

solutions. Due to the potentially high net data rates, connec-

tions must often be held only for a short time, for example

when downloading new firmware or uploading sensor data.

Li-Fi Board-to-Board Communication

High-frequency signals are commonly transmitted between

two circuit boards via HF connectors. Higher data rates require

more complex connector constructions in order to reliably send

signals. Unfortunately, it is often the case that delicately-struc-

tured HF connectors are expensive and in practice, mechanical-

ly fragile. Contacts often become bent or loose and connectors

can be replugged only a limited number of times. The Fraun-

hofer IPMS is designing Li-Fi modules to replace vulnerable HF

connectors on printed circuit boards and thus ensure reliable

board-to-board communication.

This allows for higher flexibility with respect to interchangeabil-

ity and installation of board modules. Furthermore, completely

new opportunities arise for the form factor and miniaturization

of systems and the galvanic decoupling of subsystems.

Fraunhofer IPMS Competences

Transceiver

Optics

ProtocolController

ElectricalInterface

Wireless Board-to-Board

Communication with up to

12.5 Gbps.

Range of Services

Li-Fi Module Characteristics

– Data Rate: kbit / s up to 12.5 Gbit / s

– Wavelengths: Infrared and Visible

– Low Power down to 7mW / Gbit / s

– Distances up to 30 m

– Smallest Package Concept: 2 × 2 × 2 mm²

– Temperature Range: Consumer or Industrial

– Laser Class 1

– Different Electrical Interfaces (e.g. USB, RS422, RS232,

CAN, HDMI, Profinet, Ethernet, Gigabit Ethernet)

– Point-to-Point and Point-to-Multipoint Solutions

– Uni- and Bi-directional Communication

– Half and Full Duplex Mode

– Plug and Play

Available Evaluation Kits

Li-Fi GigaDock Eval Kits

Transceiver Type Data Rate

GD-1G ≤ 1 Gbit / s

GD-5G ≤ 5 Gbit / s

GD-10G ≤ 10 Gbit / s

Li-Fi Hotspot Eval Kits

Transceiver Type Data Rate

HS-1M ≤ 1 Mbit / s

HS-10M ≤ 10 Mbit / s

HS-100M ≤ 100 Mbit / s

HS-1G ≤ 1 Gbit / s

Fraunhofer IPMS Services

Consulting Services » Guidance for decisions which may change the world.

Feasibility Tests » Use our know-how to verify your ideas.

Research and Development » Innovation for our future.

Module Prototyping » Make your vision a product.

Optical & HF Simulation » Plan before acting.

Customized Transceiver Design » No compromises.

Transceiver Test and Qualification » Clarify your stance.

Eye Safety and Laser Class Measurement » Safety first.

Eye Diagram and Jitter Measurements » Everything sharp and clear.

Short ProfileBased in Dresden, Fraunhofer IPMS is your research and service partner for the fields of optical

sensors and actuators, integrated circuits, microsystems (MEMS / MOEMS) and nanoelectronics.

As one of currently 67 independent institutes of the Fraunhofer Society for the advancement of

applied research, the leading European organization for industry-related research, our approxi-

mately 280 scientists work together with industrial and service companies as well as the public

sector on projects directly benefiting both business and society. In recognition of our customers’

high standards, the Fraunhofer IPMS is certified in accordance with DIN EN 9001:2008 to re-

search, develop and manufacture photonic microsystems, relevant semiconductor and microsys-

tem processes and integrated actuators / sensors as well as to provide DEKRA consulting.

We are committed to the research and development of technology for tomorrow’s high-speed

networks in the field of optical wireless communication. We utilize light, both from the infrared

and visible spectrums, as a wireless transmission medium. Our Li-Fi technology uses bandwidths

of several gigabits per second and has the potential to transmit data up to one ten times faster

than currently available wireless solutions with a negligible bit error rate of 10-9 per second. To-

gether with industry partners, we have founded the new industry platform ”Li-Fi Consortium“ in

2011, enabling us to drive industry-suitable technology developments in markets characterized

by different standards as well as promote and market optical technologies and applications. With

our years of experience, we offer application oriented contract research, technology solutions

and product development as well as prototype and pilot series production for a variety of Li-Fi

application scenarios.

Fraunhofer Institute for Photonic Microsystems IPMS

Maria-Reiche-Str. 2

01109 Dresden, Germany

Phone: +49 351 88 23-0

Fax: +49 351 88 23-266

info@ipms.fraunhofer.de

www.ipms.fraunhofer.de

Li-Fi – Optical Wireless Communication