|Subject:||Re: [Discuss-gnuradio] Viterbi--OFDM|
|Date:||Fri, 10 Sep 2010 14:47:18 -0400|
|User-agent:||Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:188.8.131.52) Gecko/20100825 Thunderbird/3.1.3|
My guess is that the inner channel (ie the combination of OFDM modulator/channel/OFDM demodulator) is producing big bursts of errors. Essentially either the packet is correctly received or completely erroneously received. In that case the outer Convolutional code cannot do much; on the contrary it deteriorates performance because of the SNR loss due to coding. One way to verify this hypothesis is to measure the error statistics of the inner channel.
The way to improve is to interleave before the inner channel with sufficient depth (multiple OFDM symbols).
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