visible light communication

[Harjasleen kaur]

Hello everyone
I am working on Visible light communication.I am facing in calculating BER as it remains same for all the frequencies of Source. Can anyone help me .
Thanx.

[aasif bashir dar]

hi harjasleen kaur,
i suggest you to upload your .osd file so that any bdy having interest will have the look on it.

hope you will reply soon

with regards

[Aabid Baba]

Hello arjasleen kaur,
As mentioned by asif if possible please upload your osd file so that someone can troubleshoot your problem.
This nobody has a clue what exactly you are doing unless and until someone is very well versed with simulating visible light communication systems in Optisystem.
Regards

[Harjasleen kaur]

Hello Aasif and aadib,

sir, i was studying this system and optisystem is a new tool for me so don’t know where can be mistakes.
Attaching my file herewith

please help.

Attachments:

1. LED-SOURCE-Direct-Detection-Optical-OFDM-System-me.osd

[Aabid Baba]

Hello Harjasleen,
Thanks for uploading the osd file. Shall look at it once tool is accessible as its normally accessible during working hours only. I hope we will be able to help you out. Please refer to the link i am attaching below. It is about the topic your title of the osd file suggests. you may get an idea. Anyways i hope your problem is solved.

Direct-Detection OFDM Example

regards

[Aabid Baba]

Hello Harjasleen,
I just tried to simulate your system. I am not much versed with FSO but when i checked the parameters in the simulation layout i found that your sequence length was 16000 something. Usually i have seen sequence length around 1028 and you were transmitting 2 samples which in my opinion is too low. But you can be right right as i don’t know your requirement.

regards

[Aabid Baba]

One more thing i noticed is that your symbol rate was just 2.5 Gbps while the bit rate was 10 Gbps.
You must not increase bit rate beyond symbol rate. I suggest you to keep symbol rate higher than bit rate instead. try to manipulate and improvise the parameters accordingly in your design and i hope you will get better results.

Regards

[Harjasleen kaur]

Hi Aabid,
thanks for the help. i’ll correct my system as told by you.

[Ranjeet Kumar]

Hi Harjasleen,
I think you must use OFDM Mod. of optisystem 13 or 14 version to get good results and BER test set instead of PBRS.
I don’t have much idea about FSO but in optical fiber channel you use this osd file and try to replace fiberby FSO.

Attachments:

1. Direct-Detection-OFDM-4-QAM3.osd

[Rajguru M. Mohan]

Hi,
When communication is carried out through visible light there are problems associated with it. The data transmission rates should be high enough so that flickering of the LED’s should not be detected. Sometimes it is possible for complete fadeout of the signals. To protect the data integrity the data should be framed, so as to detect lost signals and to ensure correct transmission and reception of the data. Computer network protocols like stop and wait algorithms are employed to solve this problem. The data can be of any form such as text, an audio, image or the video.For the communication to be full duplex it requires a downlink and an uplink. The downlink is implemented using the visible light. Whereas the uplink is provided using Infrared LED’s, as visible light would serve no purpose of illumination. Here e LED luminaires can be used
for high speed data transfer. The Visible Light Communication (VLC) can complement
the RF-based mobile communication systems in designing
high-capacity mobile data networks. Second, due to its high
frequency, visible light cannot penetrate through most objects
and walls. This characteristic allows one to create small cells of
LED transmitters with no inter-cell interference issues beyond
the walls and partitions. It can also increase the capacity of
available wireless channel dramatically. The inability of signals
to penetrate through the walls also provides an inherent wireless
communication security. Third, VLC facilitates the reuse of existing
lighting infrastructure for the purpose of communication.

Thanks,

[Rajguru M. Mohan]

Hi,
VLC Transmitter
The transmitter in a visible light communication system is
an LED luminaire. An LED luminaire is a complete lighting
unit which consists of an LED lamp, ballast, housing and
other components. The LED lamp (also referred as an LED
bulb in simpler terms) can include one or more LEDs. The
lamp also includes a driver circuit which controls the current
flowing through the LEDs to control its brightness. When an
LED luminaire is used for communication, the driver circuit is
modified (further details in Section V) in order to modulate the
data through the use of emitted light. A crucial design requirement for VLC system is that illumination,
which is the primary purpose of the LED luminaries,
should not be affected because of the communication
use. Hence, performance of the VLC system is also affected
depending on how the LED luminaires are designed. White
light is by far the most commonly used form of illumination
in both indoor as well as outdoor applications. This is because
colors of objects (also known as color rendering) as seen under
the white light closely resemble the colors of the same objects
under the natural light.In solid-state lighting, the white light is
produced in following two ways-Blue LED with Phosphor and RGB Combination

Thanks,

[Karan Ahuja]

Hi Harjasleen.

As far as your query is concerned i would like to share that solid-state lighting is a rapidly developing field. White-light and other visible LEDs are becoming more efficient, have high reliability and can be incorporated into many lighting applications. Recent examples include car head-lights based on white LEDs, and LED illumination as an architectural feature. The prediction that general illumination will use white LEDs in the future has been made, due to the increased energy efficiency that such an approach may have. Such sources can also be modulated at high-speed, offering the possibility of using sources for simultaneous illumination and data communications. Such visible light communications (VLC) was pioneered in Japan, and there is now growing interest worldwide, including within bodies such as the Visible Light Communications Consortium (VLCC) and the Wireless World Research Forum (WWRF).
Here is link of one paper.
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4699964&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D4699964

In this paper we outline the basic components in these systems, review the state of the art and discuss some of the challenges and possibilities for this new wireless transmission technique. I hope this will help.

Thanks

[Karan Ahuja]

I want to add that LED lights are becoming widely used for homes and offices for their luminous efficacy improvement. Visible light communication (VLC) is a new way of wireless communication using visible light. Typical transmitters used for visible light communication are visible light LEDs and receivers are photodiodes and image sensors. We present new applications which will be made possible by visible light communication technology. Location-based services are considered to be especially suitable for visible light communication applications.
You may check these papers for further study.I hope this will be helpful.
http://www.ieee802.org/802_tutorials/2008-03/15-08-0114-02-0000-VLC_Tutorial_MCO_Samsung-VLCC-Oxford_2008-03-17.pdf
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6533776&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel7%2F6526700%2F6533752%2F06533776.pdf%3Farnumber%3D6533776

Thanks

[Karan Ahuja]

Here is one more paper.
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=1649137&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D1649137

In this paper wireless communication using white, high brightness LEDs (light emitting diodes) is considered. In particular, the use of OFDM (orthogonal frequency division multiplexing) for intensity modulation is investigated. The high peak-to-average ratio (PAR) in OFDM is usually considered a disadvantage in radio frequency transmission systems due to non-linearities of the power amplifier. It is demonstrated theoretically and by means of an experimental system that the high PAR in OFDM can be exploited constructively in visible light communication to intensity modulate LEDs. It is shown that the theoretical and the experimental results match very closely, and that it is possible to cover a distance of up to one meter using a single LED. You may refer to this one. It may be useful to you

[Karan Ahuja]

I also want to add that White LED offers advantageous properties such as high brightness, reliability, lower power consumption and long lifetime. White LEDs are expected to serve in the next generation of lamps. An indoor visible-light communication system utilizing white LED lights has been proposed from our laboratory. In the proposed system, these devices are used not only for illuminating rooms but also for an optical wireless communication system. Generally, plural lights are installed in our room. So, their optical path difference must be considered. In this paper, we discuss about the influence of interference and reflection. Based on numerical analyses, we show that the system is expected to be the indoor communication of the next generation.
One more paper is here
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=1277847&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F30%2F28566%2F01277847.pdf%3Farnumber%3D1277847

[Karan Ahuja]

I want to add that Visible light communication refers to shortrange optical wireless communication using visible light spectrum from 380 to 780 nm. Enabled by recent advances in LED technology, IEEE 802.15.7 supports high-data-rate visible light communication up to 96 Mb/s by fast modulation of optical light sources which may be dimmed during their operation. IEEE 802.15.7 provides dimming adaptable mechanisms for flicker-free high-data-rate visible light communication.The method of transmitting an image and an audio song using visible light and successful reproduction has been shown, thereby, presenting a feasible method of using visible light for safe and cheap data transfer. The various steps to achieve transmission and faithful reproduction of the image and also transmission of an audio song have been described. Though, this technology is still in its infancy, with further studies and development its far-reaching applications will only get better.
The VLC technology is all about using LED light bulbs meant for illumination to also send data simultaneously. It is best suited as an additional option for data transfer where radio transmission networks are not desired or not possible. In future, we can transmit an image, audio and even an high definition video using an LED light bulbs

I am attaching links of few papers you may refer to these for further study. I hope these will help.
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6163585&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6163585
http://www.ijcttjournal.org/Volume4/issue-4/IJCTT-V4I4P195.pdf

Thanks

[burhan num mina llah]

Hello Harjasleen Kaur,

There are few things you may do to increase the performance of your system that is reduce the bit error rate (BER) and increase the quality factor.
Firstly you may try increasing the launching power although it has its own repercussions but if you want low bit error rate this can be one option. Secondly, as mentioned by Aabid Baba you may increase the symbol rate and keep it more than the bit rate of the system.
One more thing you can try is increasing the length of the sequence of the data stream which reduces the probability of error. You may take these factors into consideration while designing your system. I hope this will help you in achieving what you desire. Thanking you

Regards

Burhan

[Author]

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