- This topic has 4 replies, 3 voices, and was last updated 9 years, 8 months ago by
alistu.
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March 2, 2016 at 10:02 am #30953
Metin Ozturk
ParticipantDear Friends.
I am trying to construct 4-QAM OFDM and 16-QAM OFDM system for Visible Light Communication.
For 4-QAM OFDM, results are OK such as BER=0 and constellaiton digram gives clear result.
However, for 16-QAM OFDM BER is not acceptabe which is 0.5. Constellation is still OK.
For 64-QAM OFDM, both BER and constellation are not acceptable.
Could you please help me regarding this problem.
My system is in the attachment.
Regards.
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March 2, 2016 at 11:26 am #30968
prakash jatParticipanthi metin
i thing as we increase constellations point we need to discernment as well as also, so if you go for increase in constellations point
in visible ligt communication then it have more phase distortion so you should use phase estimation technique as well as mimo techniqueregards
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March 2, 2016 at 12:59 pm #30991
alistuParticipantHi Metin,
since you are using Optisystem 12 OFDM components, I suggest you go through the answer provided by Damian regarding some changes that should be applied in 16-QAM and 64-QAM implementations with OS12 OFDM component. Please see if it helps:
Regards
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March 2, 2016 at 5:43 pm #31034
Metin Ozturk
ParticipantThank you for your answers.
Alitsu, that system is working well, but when i change the CW Laser parameters as Frequency=550 nm and Linewidth=300 GHz to cover whole visible range, results get worse. Do you have any idea aout this?
Thank you.
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March 2, 2016 at 7:40 pm #31045
alistuParticipantHi Metin,
When one parameter in the system changes, there are some other parameters that need to change accordingly in the system. For example, in the receiver PIN, you may have chosen the center frequency as the value formerly used. Please check all these parameters to see if they are consistent.
Regards
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