[USRP-users] How to calculate packets live from USRPN200 hardware

Mariam Musavi mariam.musvi at gmail.com
Tue Mar 29 11:28:38 EDT 2016


Hi Marcus!

I agree the things you mentioned in your recent email, but i am still not
agreeing with "There is nothing that one can do to predict/measure
throughput "in general", all depends on your system design". Since i am
working more on Network layer, If we see USRP hardware has front panel
LEDs, describing functionalities few of them i am mentioning such as
LED A: transmitting
and LED C: receiving, when we talk about ettus Network series USRP N200, we
normally talk about packets and system configuration isn't it (sorry that,
i am more indulge into working on to network layer in IP stack). The device
which transmit data to another device (assuming in my case each USRP is
equipped with system design which i made in GRC flowgraph with the
following  parameters: Packet size: 2720 bits, Transmission rate:
1Mbps, Modulation: GMSK), My question is how can i measure each node's
parameters such as packets (sent/receive) independently in GRC, without
using any network analyzer software?

On Tue, Mar 29, 2016 at 8:07 PM, Mariam Musavi <mariam.musvi at gmail.com>
wrote:

> Hi Marcus!
> LED A: transmitting
> LED C: receiving
>
> On Tue, Mar 29, 2016 at 7:14 PM, Marcus Müller <marcus.mueller at ettus.com>
> wrote:
>
>> Mariam,
>>
>> as mentioned, "throughput" is a very high-level concept.
>>
>> At the physical layer, where we're currently discussing, you can only
>> *select* a given bandwidth/modulation/coding combination and hence *set*
>> the throughput.
>> This selection of methods and parameters depends alone on how you want
>> your system to behave, and how you model your channel.
>>
>> As said multiple times now, you're the one defining bit rate, and your
>> channel and the methods used will lead to an error rate. There's nothing
>> that one can do to predict/measure throughput "in general"; all depends on
>> your system design.
>>
>> Best regards,
>> marcus
>>
>>
>> On 29.03.2016 15:17, Mariam Musavi wrote:
>>
>> Hi Marcus!
>>
>> I am really sorry that i couldn't elucidate my problem clearly to the
>> USRP community, i agree with the point that USRP only knows the language of
>> waveform. My problem is i simulate a noise to provide to USRP node. Since i
>> feed that simulated noise to USRP, it will response to that noise resulting
>> (lower SNR), providing less throughput. i basically want to measure the
>> throughput of each node while sending (video data) waveform in the presence
>> of simulated noise. Is there any block in GRC/USRP which can measure
>> the throughput in hop-to-hop manner of each node from USRP source to USRP
>> destination?
>>
>> Let me know Marcus if the problem is still unclear!
>>
>> Thanks.
>>
>> On Tue, Mar 29, 2016 at 6:01 PM, Marcus Müller <marcus.mueller at ettus.com>
>> wrote:
>>
>>> Mariam,
>>>
>>> the point still is that the USRP really doesn't know (and care) what
>>> your samples mean. To the USRP, these are just relative voltage values.
>>> The fact that it's data is up to your software's interpretation of these
>>> values; you can't transmit "bits" over the air, but you can transmit a
>>> waveform that can be interpreted as such.
>>>
>>> So, a USRP can't forward "data"; it just receives RF signal, makes a
>>> digital signal out of it, gives that to a PC, which might then do something
>>> with that, eg. take the same digital numbers and give it to a USRP to make
>>> a TX signal out of it.
>>>
>>> I'm having a bit of a hard time understanding in what kind of "deadlock"
>>> you are. That is probably because I don't understand you correctly; could
>>> you explain your problem?
>>>
>>> Best regards,
>>> Marcus
>>>
>>>
>>> On 29.03.2016 14:40, Mariam Musavi wrote:
>>>
>>> video data packets.
>>>
>>> On Tue, Mar 29, 2016 at 4:17 PM, Marcus Müller <
>>> <marcus.mueller at ettus.com>marcus.mueller at ettus.com> wrote:
>>>
>>>> Hi Mariam,
>>>>
>>>> what packets are you referring to?
>>>>
>>>> Best regards,
>>>> Marcus
>>>>
>>>>
>>>> On 29.03.2016 12:06, Mariam Musavi wrote:
>>>>
>>>> Greetings!
>>>>
>>>> All users,
>>>>
>>>> I am working on USRP Network series N200, and i am stuck up in the
>>>> deadlock to calculate packets sent/received during transmission from USRP
>>>> node. There are two cases:
>>>>
>>>> 1. Calculate packets offline (end-to-end): if i want to calculate
>>>> end-to-end packet delivery, i used third-party Network Analyzer software.
>>>>
>>>> 2. Calculate packets online: (hop-to-hop) but since i want to calculate
>>>> real-time packets sent/received from USRP source node to USRP destination
>>>> node.
>>>>
>>>> For instance, the network scenario is described as setting up three
>>>> USRPs that are connected to a computer through ethernet switch. USRP source
>>>> node forwards data packets (or video) to second USRP (i.e., relay node) and
>>>> finally the second USRP  forwards the data packets to USRP destination
>>>> node. For transmission of packets i use a video file.
>>>>
>>>> Looking forward for help. Thanks.
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>> --
>> Syed Mariam
>> Graduate Research Assistant
>> Sunway University (Malaysia) & Lancaster University
>> (UK) joint program.
>>
>>
>>
>
>
> --
> Syed Mariam
> Graduate Research Assistant
> Sunway University (Malaysia) & Lancaster University
> (UK) joint program.
>



-- 
Syed Mariam
Graduate Research Assistant
Sunway University (Malaysia) & Lancaster University
(UK) joint program.
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