Pilot and Training symbols

[Ranjeet Kumar]

Hi everyone,
Can anyone explain the significance of pilot and training symbols as it is not in OS12 but in optisystem 13 or 14 we have OFDM modulator with pilot and training symbols. I am able to understand that why we connect this port to corresponding port in OFDM demodulator.
Hare i am uploading osd file OFDM system, in this how could i calculate Q-factor and Min. BER. If anyone could explain it.

Attachments:

1. Direct-Detection-OFDM-4-QAM2.osd

[ZULKARNAIN]

hi ranjeet…
Pilot sequences are the unmodulated data we are transmitting along with the data.Pilots are used for syncronization and Channel estimation purposes. Channel estimation is the main thing we need to concentrate for improving the channel capacity .
More the number of pilots more efficeintly we can estimate the channel and increase the capacity . But as pilots increases overhead increases. so the selection of pilots is such that tradeoff should be considered between pilots symbols and spectral efficiency. In IEEE 802.11 OFDM standard we are using 64 subcarreirs per OFDM symbol in these 64 , 48 are for data and 4 are Pilot and remaining are for zeropadding .
http://www.edaboard.com/thread219563.html
Hope you may get benefited from this.
with regards

[ZULKARNAIN]

Explaining further..
The pilot tones and training sequence are in fact transmitted along with the signal. The top port that you connect directly to the OFDM demodulator is what the demodulator compares the received pilot/training symbols to. In a REAL system the receiver is programmed to know what pilot tone/training symbols it expects and compares it to the detected signal which is a combination of the overhead and the actual information.
In the simulation, as I mentioned the pilot tones/training symbols make up part of the transmitted signal, and the port coming out the top is the undistorted pilot and training sequence tones the receiver compares the detected signal too.

need help with my project

[Ranjeet Kumar]

Thanks ZULKARNAIN for your kind information.
In most design where i have OFDM mod. instead of OS12 we have problem in getting BER ans Q-factor.
I above design i request that if possible please suggest ways to get BER and Q-factor.
seeking for your response.

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