WARP Project Forums - Wireless Open-Access Research Platform

You are not logged in.

#1 2018-Feb-09 11:20:56

mmcruirong
Member
Registered: 2017-Sep-20
Posts: 18

Warp3 node as receiver for all wireless signals

Hi,

I am currently working with warp3 and 802.11 reference design. I am able to have the frequency offset for WIFI signal using log. But I want to use WARP3 as a receiver that calculate all wireless signal from ADC to compute the frequency offset from those signals, like Zigbee signal. It seems current log file only capture valid OFDM or DSSS signals. Is there any way we can make WARP capture and calculate frequency offset from all wireless signals?

Another question, if I want to communicate between warp and USRP and retrieve the data transmitted from USRP?

Thank you!
Ruirong Chen

Offline

 

#2 2018-Feb-09 13:00:54

chunter
Administrator
From: Mango Communications
Registered: 2006-Aug-24
Posts: 1184

Re: Warp3 node as receiver for all wireless signals

mmcruirong wrote:

I am currently working with warp3 and 802.11 reference design. I am able to have the frequency offset for WIFI signal using log. But I want to use WARP3 as a receiver that calculate all wireless signal from ADC to compute the frequency offset from those signals, like Zigbee signal. It seems current log file only capture valid OFDM or DSSS signals. Is there any way we can make WARP capture and calculate frequency offset from all wireless signals?

No, the 802.11 Reference Design can only decode and log 802.11 signals (i.e. DSSS and OFDM). A real-time design that is capable of decoding other kinds of non-802.11 waveforms would be an extremely challenging extension and may not even fit into the FPGA. Depending on what your application is, you may have success with the WARPLab Reference Design to capture a long 40MHz-wide waveform that contains a bunch of signals that you care about. At a minimum, you can use something like the Spectrogram example to see when energy on the medium occurs and over which frequencies.


mmcruirong wrote:

Another question, if I want to communicate between warp and USRP and retrieve the data transmitted from USRP?

If WARP is using the 802.11 Reference Design then it will receive any packet that uses one of the supported 802.11 rates. This is true regardless of who is sending the packet. I think there are some projects out there that implement parts of the 802.11 transmitter on the USRP. You could probably find one that will send a valid DSSS or OFDM waveform that our design can then decode.

Offline

 

#3 2018-Feb-09 15:45:53

mmcruirong
Member
Registered: 2017-Sep-20
Posts: 18

Re: Warp3 node as receiver for all wireless signals

Thanks chunter,

We just need to have the frequency offset from the short training sequence or long training sequence of the signal, we wants to see how the 802.11 demo works. From the 802.11 demo, is there anyway we can have the cfo_est for all signals in a specific time, like record the cfo_est without WIFI data transmission in 10s, by modifying python , C program or PHY?

If we cant do it with, can we build a LTS or short training sequence in WARPLAB?

Thanks for the advice! Have a nice weekend

Ruirong Chen

Offline

 

#4 2018-Feb-09 16:08:02

murphpo
Administrator
From: Mango Communications
Registered: 2006-Jul-03
Posts: 4964

Re: Warp3 node as receiver for all wireless signals

From the 802.11 demo, is there anyway we can have the cfo_est for all signals in a specific time, like record the cfo_est without WIFI data transmission in 10s, by modifying python , C program or PHY?

I don't understand what you mean by "cfo_est for all signals...without Wi-Fi". The 802.11 Ref Design Rx PHY implements CFO estimation as part of its Rx processing. The Rx PHY cannot estimate CFO for non-802.11 waveforms.

Offline

 

#5 2018-Feb-12 12:39:27

mmcruirong
Member
Registered: 2017-Sep-20
Posts: 18

Re: Warp3 node as receiver for all wireless signals

We are trying to see if we can calculate CFO from Zigbee using default 802.11 reference design. This is what we currently doing. From the simulation, CFOs can be calculated using LTS from 802.11 as in the 802.11 reference design, even for the Zigbee signals(Zigbee signals have huge CFOs with standard 802.11 LTS detection). 

I am currently looking into the wlan_phy_rx_pmd design and find out there is I/Q Valid signal. So I am wondering instead of dropping the non 802.11 signals, can the 802.11 reference design pass the non 802.11 signals for CFO detection?  Can we set the I/Q valid signal to be valid for zigbee signals received by PHY_Rx?   Or is there anything I can do without modifying the PHY_Rx design, but changing the C or python file can enable us to do some testing with frequency offset using 802.11 reference design for Zigbee signals.

We are trying to see if we can have some CFOs using standard 802.11 receiver.  If it cant we will try to build the LTS detection using Warp_Lab.

Sorry for the confusion in this question

Thanks
Ruirong Chen

Offline

 

#6 2018-Feb-12 14:06:37

murphpo
Administrator
From: Mango Communications
Registered: 2006-Jul-03
Posts: 4964

Re: Warp3 node as receiver for all wireless signals

We are trying to see if we can calculate CFO from Zigbee using default 802.11 reference design

I do not believe this is possible. I don't know the Zigbee spec, but I think it uses a completely different waveform (this app note has some Zigbee PHY details). The CFO estimator in our 802.11 Rx PHY is designed specifically for the 802.11 OFDM waveform; it cannot calculate meaningful CFO estimates for other waveforms.

Offline

 

#7 2018-Feb-12 15:51:17

mmcruirong
Member
Registered: 2017-Sep-20
Posts: 18

Re: Warp3 node as receiver for all wireless signals

Thank you so much for your reply. Zigbee did use different signal wave form. From simulation, we uses WIFI receiver as implemented in 802.11 design, the LTS can differentiate zigbee signal and WIFI signals, since zigbee signals has huge CFO. I want to know how to make the 802.11 reference design wont drop the I/Q data from zigbee signals. Is it possible to do so?

Thanks
Ruirong Chen

Offline

 

#8 2018-Feb-12 20:24:22

murphpo
Administrator
From: Mango Communications
Registered: 2006-Jul-03
Posts: 4964

Re: Warp3 node as receiver for all wireless signals

The 802.11 Rx PHY consumes a continuous stream of IQ samples. Most of the Rx PHY pipeline is idle until the packet detection logic observes an OFDM waveform in the IQ sample stream. After an OFDM preamble is detected the rest of the Rx PHY begins processing the IQ samples for reception.

Offline

 

#9 2018-Feb-13 12:47:58

mmcruirong
Member
Registered: 2017-Sep-20
Posts: 18

Re: Warp3 node as receiver for all wireless signals

Murphpo wrote:

The 802.11 Rx PHY consumes a continuous stream of IQ samples. Most of the Rx PHY pipeline is idle until the packet detection logic observes an OFDM waveform in the IQ sample stream.

Thanks Murphpo, so if I set the Pkt OFDM det signal to be always 1 and change the scale in CFO est block, the PHY will pass all the I/Q signal and recognized them as OFDM packet and calculate the CFO for those signals right?

Thanks

Offline

 

#10 2018-Feb-13 13:44:07

murphpo
Administrator
From: Mango Communications
Registered: 2006-Jul-03
Posts: 4964

Re: Warp3 node as receiver for all wireless signals

so if I set the Pkt OFDM det signal to be always 1 and change the scale in CFO est block, the PHY will pass all the I/Q signal and recognized them as OFDM packet and calculate the CFO for those signals right?

No - the CFO estimation logic in the 802.11 Rx PHY can only calculate CFO estimates using the preamble of an 802.11 waveform. The "cfo_est" signal in the Rx PHY will not provide a meaningful CFO estimate for any other waveform.

Offline

 

Board footer