Optical Spatial Modulation OFDM using Micro LEDs

Presented by,Basil JacobRoll no: 19S7 ECE AVJCET

Contents OFDM

Visible light Communication

MIMO systems

Optical Spatial Modulation

Optical Spatial Multiplexing

Micro LEDs

OSM-OFDM using Micro LEDs

Inference

References 2

Modulation Vs Multiplexing

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₪ Modulation – Mapping of the information on

changes in the carrier phase, frequency or amplitude or combination

₪ Multiplexing – Method of sharing a bandwidth with other independent data channels

Orthogonal Frequency Division Multiplexing

OFDM is a combination of Modulation and Multiplexing

Digital data encoded on multiple carrier frequencies

Sub-carriers are orthogonal to each other

Used in Asymmetric Digital Subscriber Line connections

Need not be wireless 4

Orthogonality

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Frequency Division Multiplexing

OFDM

Analogy

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OFDM - Block diagram

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Source: http://ee.bradley.edu/projects

Time/Frequency Domain

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Source: https://eventhelix.files.wordpress.com

OFDM Transmitter

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Source: https://en.wikipedia.org/wiki/File:OFDM_transmitter_ideal.png

OFDM Receiver

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Source: https://en.wikipedia.org/wiki/File:OFDM_transmitter_ideal.png

Visible Light Communication systems

€ Uses visible light between 400 and 800 THz (780–375 nm)

€ Fluorescent lamps ( 10 Kbit/s ) , LEDs ( 500 Mbit/s )

€ Organic LEDs (OLED) as optical transceivers achieve 10 Mbit/s

€ Modulation transforms data into a series of light pulses

€ Frequency of light pulses is modulated & not the frequency of light

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VLC - Motivation

∞ Visible light does not cause health problems

∞ Expensive patent-license is not needed

∞ No Electromagnetic Interference

∞ Safe to use in hospitals

∞ LEDs -the predominant choice - very short switching time 12

Multiple Input Multiple Output system

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Source: https://en.wikipedia.org/wiki/File:MIMO.png

Optical Spatial Modulation

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Source: article.sapub.org

OSM using LEDs

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Source : Reference 4

Optical Spatial Multiplexing (OSMX)

Each spatial channel carries independent information

Increases the data rate of the system

No additional cost on bandwidth or power

Bit Error Rate is more

Higher computational complexity

Inter-antenna synchronization is required

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Micro LEDs

Diameter of about 12 µm

Can flicker 1,000 times faster than commercial LEDs

Enhanced quantum efficiencies for the same area

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Source: www.element14.com

OSM OFDM using µLEDs

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Source: Reference 1

OSM-OFDM using µLEDs

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Source: Reference 1

OSM OFDM using µLEDs Vs

OSMX OFDM

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Achievable Data Rate

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Source: Reference 1

Data Rate vs Semi-angle

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Source : Reference 1

Bit Error Rate

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Source : Reference 1

BER vs Semi-angle

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Source : Reference 1

Computational Complexity

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Source : Reference 1

Inference ₪ OSM-OFDM using µLEDs

Better than OSMX-OFDM in terms of computational complexity

Achieves data rate up to 5.5 Gb/s

₪ OSMX OFDM

Data rates of up to 6 Gb/s are feasible

₪ BER depends largely on spatial separation between the transmitters(ds) and on the half- power semi-angle of the µLEDs (φ1/2)

₪ Optimum conditions :- larger spatial separation, a smaller half power semi-angle

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References1. M. Ijaz et al., "Optical spatial modulation OFDM using micro LEDs," 2014 48th Asilomar Conference on Signals, Systems and Computers, Pacific Grove, CA, 2014, pp. 1734-1738. doi: 10.1109/ACSSC.2014.7094764

2. M. Ijaz et al., "Experimental proof-of-concept of optical spatial modulation OFDM using micro LEDs," 2015 IEEE International Conference on Communication Workshop (ICCW), London, 2015, pp. 1338-1343. doi: 10.1109/ICCW.2015.7247364

3. R. Mesleh, H. Elgala and H. Haas, "Optical Spatial Modulation," in IEEE/OSA Journal of Optical Communications and Networking, vol. 3, no. 3, pp. 234-244, March 2011. doi: 10.1364/JOCN.3.000234

4. R. Mesleh, R. Mehmood, H. Elgala and H. Haas, "Indoor MIMO Optical Wireless

Communication Using Spatial Modulation," Communications (ICC), 2010 IEEE

International Conference on, Cape Town, 2010, pp. 1-5. doi: 10.1109/ICC.2010.5502062

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