The document presents a detailed examination of optical spatial modulation OFDM using micro LEDs, covering key concepts such as OFDM, visible light communication, and multi-input multi-output systems. It highlights the advantages of micro LEDs over traditional LEDs, including faster flicker rates and higher quantum efficiencies, and discusses the achieved data rates and bit error rates associated with this technology. The findings indicate that osm-OFDM using micro LEDs can achieve a data rate of up to 5.5 Gb/s, outperforming other methods in terms of computational complexity.

1. Optical Spatial
Modulation OFDM
using Micro LEDs
Presented by,
Basil Jacob
Roll no: 19
S7 ECE A
VJCET

2. Contents
 OFDM
 Visible light Communication
 MIMO systems
 Optical Spatial Modulation
 Optical Spatial Multiplexing
 Micro LEDs
 OSM-OFDM using Micro LEDs
 Inference
 References
2

3. Modulation Vs Multiplexing
3
₪ 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

4. 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

5. Orthogonality
5
Frequency
Division
Multiplexing
OFDM

6. Analogy
6

7. OFDM - Block diagram
7
Source: http://ee.bradley.edu/projects

8. Time/Frequency Domain
8
Source: https://eventhelix.files.wordpress.com

9. OFDM Transmitter
9
Source: https://en.wikipedia.org/wiki/File:OFDM_transmitter_ideal.png

10. OFDM Receiver
10
Source: https://en.wikipedia.org/wiki/File:OFDM_transmitter_ideal.png

11. 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
11

12. 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

13. Multiple Input Multiple Output
system
13
Source: https://en.wikipedia.org/wiki/File:MIMO.png

14. Optical Spatial Modulation
14
Source: article.sapub.org

15. OSM using LEDs
15
Source : Reference 4

16. 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
16

17. Micro LEDs
 Diameter of about 12 µm
 Can flicker 1,000 times faster than commercial LEDs
 Enhanced quantum efficiencies for the same area
17
Source: www.element14.com

18. OSM OFDM using µLEDs
18
Source: Reference 1

19. OSM-OFDM using µLEDs
19
Source: Reference 1

20. OSM OFDM using µLEDs
Vs
OSMX OFDM
20

21. Achievable Data Rate
21
Source: Reference 1

22. Data Rate vs Semi-angle
22
Source : Reference 1

23. Bit Error Rate
23
Source : Reference 1

24. BER vs Semi-angle
24
Source : Reference 1

25. Computational Complexity
25
Source : Reference 1

26. 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
26

27. References
1. 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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