11ECE 70
1
• 11/ECE/70; 8th SEMESTER
• ELECTRONICS AND
COMMUNICATIONS ENGG
• RIKARNOB BHATTACHARYYA
SEMINAR: ADVENT OF LIGHT FIDELITY (LiFi)
NIT DURGAPUR
Presentation contents
INTRO
WORKIN
G
STANDARD
S
CHALLENG
ES
APPLICATIO
NS
CONCLUSIO
N
2
INTRODUCTION
As has been introduced in the abstract, LiFi works with the help of LEDs. A special light bulb in question will have several LEDs (the LED will be made from Gallium Nitride or GaN) each of which will be transmitting an array or a stream of bits
(0s and 1s). The bit-stream can be modulated using a standard modulation scheme. Speeds of
700Mbps-1Gbps can be achieved.
3
INTRODUCTION (contd.)
In order to send effectively communicate via light, there should be receivers specially suited for this purpose. Photodiode receivers or CCD/CMOS sensors can be used (typically found in digital cameras).
4
WORKING
Resonant Cavity LED is being used for transmission purpose. This will allow modulation at very high frequencies.
Receivers may include CMOS or CCD
(Charge Coupled Device) sensors.
To prevent interference between bit streams, modulation is employed.
Common modulation scheme (like FSK) is used. For faster transmission of data
SIM-OFDM is used.
5
WORKING (contd.)
The following flowchart shows a schematic of how the flow of information takes place.
6
EXAMPLE OF FSK
Following shows a graphical representation of BFSK where two frequencies have been used.
7
STANDARDS
To standardize communication thorugh light, there exists two JEITA standards
(JEITA CP-1221 and JEITA CP-1222).
The JEITA CP-1221 restricts the wave length of all emitted light to be within a range of 380 nm to 750 nm. Wavelength accuracy of application should be 1nm.
JEITA CP-1222 restricts the subcarrier frequency to 28.8 kHz and requires cyclic reduncancy checks (CRC) for error detection and correction.
8
CHALLENGES FACED
Line of Sight transmission is not always possible and VLC fails when a visible LOS is
• 11/ECE/70; 8th SEMESTER
• ELECTRONICS AND
COMMUNICATIONS ENGG
• RIKARNOB BHATTACHARYYA
SEMINAR: ADVENT OF LIGHT FIDELITY (LiFi)
NIT DURGAPUR
Presentation contents
INTRO
WORKIN
G
STANDARD
S
CHALLENG
ES
APPLICATIO
NS
CONCLUSIO
N
2
INTRODUCTION
As has been introduced in the abstract, LiFi works with the help of LEDs. A special light bulb in question will have several LEDs (the LED will be made from Gallium Nitride or GaN) each of which will be transmitting an array or a stream of bits
(0s and 1s). The bit-stream can be modulated using a standard modulation scheme. Speeds of
700Mbps-1Gbps can be achieved.
3
INTRODUCTION (contd.)
In order to send effectively communicate via light, there should be receivers specially suited for this purpose. Photodiode receivers or CCD/CMOS sensors can be used (typically found in digital cameras).
4
WORKING
Resonant Cavity LED is being used for transmission purpose. This will allow modulation at very high frequencies.
Receivers may include CMOS or CCD
(Charge Coupled Device) sensors.
To prevent interference between bit streams, modulation is employed.
Common modulation scheme (like FSK) is used. For faster transmission of data
SIM-OFDM is used.
5
WORKING (contd.)
The following flowchart shows a schematic of how the flow of information takes place.
6
EXAMPLE OF FSK
Following shows a graphical representation of BFSK where two frequencies have been used.
7
STANDARDS
To standardize communication thorugh light, there exists two JEITA standards
(JEITA CP-1221 and JEITA CP-1222).
The JEITA CP-1221 restricts the wave length of all emitted light to be within a range of 380 nm to 750 nm. Wavelength accuracy of application should be 1nm.
JEITA CP-1222 restricts the subcarrier frequency to 28.8 kHz and requires cyclic reduncancy checks (CRC) for error detection and correction.
8
CHALLENGES FACED
Line of Sight transmission is not always possible and VLC fails when a visible LOS is
References: 1. 2. DSP for LED based Visible light communication (Chow, Yeh, Liu, Liu). Visible Light Communication (Christian Pohlmann). 14 THANK YOU 15