wlanhdlreceiver use only 64 sample to do fine symbol timming. is it enough for 40M, 80M and 16MHz wlan signal?

I am learning on the wlanHDLReceiver HDL design. the Design uses 64 data to do fine symbol timing. But in Matlab .m reference design, it uses entire LLTF signal to do fine symbol timing. It means for 40MHz, or 80MHz wlan signal, it will use 128 or 256 samples. Do you think the wlanHDLReceiver taking only 64 sample to do fine symbol timing will have performance issue at 40M, 80M, or 160MHz wlan signal?

Answer 1

[Pravalika Chalukuti]

Hello Xiaodong,

The Matlab reference uses the ‘wlanSymbolTimingEstimate’ function to perform the fine timing synchronization using L-LTF. This function uses the complete length of the known L-LTF signal (160 or 320 samples for 20 MHz or 40 MHz channel bandwidth, respectively) to perform cross-correlation with the input for fine timing synchronization.

On the other hand, the ‘wlanhdlReceiver’ HDL model uses a 64-sample correlation for fine timing synchronization for both 20 MHz and 40 MHz channel bandwidth option. Reducing the correlation window length from the complete L-LTF signal length to effective 64 L-LTF samples will not significantly impact the performance of the fine timing estimation. Additionally, it helps in decreasing the usage of HDL resources and improve timing in the HDL implementation. You can also configure the correlation window length 'wlanConfig.corrLen' in 'wlanhdlReceiverInit.m' file to same as that in the Matlab reference and verify the performance of the HDL receiver design.

Hope that helps,

Pravalika