VHTMIMOPac​ketErrorRa​teExample - Why is LDPC on IEEE 802.11ac worst than BCC ??

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Hi All, I ran the WLAN System Toolbox example VHTMIMOPacketErrorRateExample, which basically provide a PER simulation of IEEE 802.11ac on a 8x8 MIMO configuration based on BCC as channel coding.
Now, I tried to use LDPC instead of BCC, and I was expecting it to perform a bit better (it does on IEEE 802.11n). But the output is totally worse...
Would anybody know where this poor performance could come from? I used the based TGacChannel and did not change anything from the example beside the channel coding.
Thanks in advance,
BR,
Jérôme

Answers (2)

BABA CHOUDHURY
BABA CHOUDHURY on 2 Jan 2019
Hi Jerome, I know its very late now to respond to your query.
Still, I was also running similar simulations and found LDPC to outperfrom BCC in every scenario. Maybe some other parameters is affecting the calculations.

Darcy Poulin
Darcy Poulin on 12 Aug 2020
I had exactly the same issue, and spoke with Mathworks support.
It turns out that you should configure the LDPC decoding method to use 'norm-min-sum' rather than the default 'bp' algorithm. When I made this change, I saw the predicted improvement in link performance.
For 11ac, you configure it like this:
rxPSDU=wlanVHTDataRecover(vhtdata,chanEst,nVarVHT,cfgVHT, 'LDPCDecodingMethod','norm-min-sum')
The same thing occurs in 11ax. Here you configure it like this:
rxPSDU = wlanHEDataBitRecover(eqDataSym,nVarEst,csi,cfgHE,'LDPCDecodingMethod','norm-min-sum');

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