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#1 2019-Jul-12 01:31:29

VATSALA SHARMA
Member
Registered: 2015-Sep-15
Posts: 26

SISO & MIMO examples

While running wl_example_siso_ofdm_txrx & wl_example_mimo_ofdm_txrx with Hardware in loop, getting msg as
>> wl_example_siso_ofdm_txrx
Too many OFDM symbols for TX_NUM_SAMPS!
Raise MAX_TX_LEN to 81445, or
Reduce N_OFDM_SYMS to 195
&
>> wl_example_mimo_ofdm_txrx
Too many OFDM symbols for TX_NUM_SAMPS!
Raise TX_NUM_SAMPS to 81964, or
Reduce N_OFDM_SYMS to 380
Reduce N_OFDM_SYMS to 380

Why so?
And my second question is when i change the value of N_OFDM_SYMS to 380 from 1000 I am getting the plots as well as the output as

Results:
Num Bytes:   9120
Sym Errors:  1704 (of 18240 total symbols)
Bit Errors:  1813 (of 72960 total bits)
CFO Est:     -1.19 kHz (-0.48 ppm)
     LTS CFO Est:                  -0.89 kHz
     Phase Error Residual CFO Est: -0.30 kHz
SFO Est:     1.84 Hz (0.09 ppm)

which is not similar to one give at the WARP website why so, please explain?

Results:
Num Bytes:   12000
Sym Errors:  0 (of 24000 total symbols)
Bit Errors:  0 (of 96000 total bits)
EVM:         6.757%
LTS CFO Est: -1.38 kHz

Last edited by VATSALA SHARMA (2019-Jul-12 01:33:00)

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#2 2019-Jul-12 10:01:33

chunter
Administrator
From: Mango Communications
Registered: 2006-Aug-24
Posts: 1212

Re: SISO & MIMO examples

VATSALA SHARMA wrote:

While running wl_example_siso_ofdm_txrx & wl_example_mimo_ofdm_txrx with Hardware in loop, getting msg as
>> wl_example_siso_ofdm_txrx
Too many OFDM symbols for TX_NUM_SAMPS!
Raise MAX_TX_LEN to 81445, or
Reduce N_OFDM_SYMS to 195
&
>> wl_example_mimo_ofdm_txrx
Too many OFDM symbols for TX_NUM_SAMPS!
Raise TX_NUM_SAMPS to 81964, or
Reduce N_OFDM_SYMS to 380
Reduce N_OFDM_SYMS to 380

Why so?

The error message is pretty clear: the number of OFDM symbols you've specified you want to send is too large given the separate definition of how many I/Q samples you want to send. Either reduce the former or increase the latter to get rid of the error. Are you using WARP v2 or WARP v3? The example assumes the larger buffer support that WARP v3 provides, so that might be why you are getting an error message with unmodified code.

VATSALA SHARMA wrote:

And my second question is when i change the value of N_OFDM_SYMS to 380 from 1000 I am getting the plots as well as the output as

Results:
Num Bytes:   9120
Sym Errors:  1704 (of 18240 total symbols)
Bit Errors:  1813 (of 72960 total bits)
CFO Est:     -1.19 kHz (-0.48 ppm)
     LTS CFO Est:                  -0.89 kHz
     Phase Error Residual CFO Est: -0.30 kHz
SFO Est:     1.84 Hz (0.09 ppm)

which is not similar to one give at the WARP website why so, please explain?

Results:
Num Bytes:   12000
Sym Errors:  0 (of 24000 total symbols)
Bit Errors:  0 (of 96000 total bits)
EVM:         6.757%
LTS CFO Est: -1.38 kHz

Are you referring to the fact that your example had symbol errors whereas our example did not? That's almost impossible for us to say why. Over-the-air transmissions are subject to channel effects or interference that can degrade a reception.

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#3 2019-Jul-12 10:07:27

VATSALA SHARMA
Member
Registered: 2015-Sep-15
Posts: 26

Re: SISO & MIMO examples

Sir I am using Warpv3 board.In that case it should support large buffers but it is asking to reduce the length why?

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#4 2019-Jul-15 09:49:16

murphpo
Administrator
From: Mango Communications
Registered: 2006-Jul-03
Posts: 5077

Re: SISO & MIMO examples

Are you using the latest (currently v7.7.1) WARPLab design on WARP v3? Did you modify the wl_example_siso_ofdm_txrx.m script? And are you using the script from the reference design archive? By default the OFDM example scripts use N_OFDM_SYMS values that are compatible with the reference FPGA design.

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