Towards an Open Source IEEE 802.11p Stack

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Video in TIB AV-Portal: Towards an Open Source IEEE 802.11p Stack

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Towards an Open Source IEEE 802.11p Stack
An SDR-based Transceiver in GNURadio
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I will discuss new ideas and application domains of our Open Source IEEE 802.11a/g/p OFDM transceiver for GNU Radio. The transceiver is implemented completely in software without the need for changing the firmware of the FPGA. For that reason, the structure and mode of operation of the transceiver is easy to understand and it is straightforward to extend. In our opinion, an SDR based WiFi transceiver has several interesting applications, one of them being its use for research in Vehicular Ad Hoc Networks (VANETs). In this field, the applications for an SDR implementation range from investigation of security and privacy issues, through simulative performance evaluation of receive algorithms, to experiments in field tests. In the talk, we discuss the possibilities and limitations of the SDR platform, as well as our current state of the art. We will highlight what is already possible, present results of our performance studies, and also show where improvements, hopefully with the help of people from the Open Source community, would be desirable.
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ch that 11 P. stack and this 11 p is a very slight about from 2 normal life I and to operate in the few environment so many like cars not equipped to meet your that hold what was formed when it's about your apart OK and and this this hold suffers is a bit embedded in a broader project with the so-called modern alignments for building and some communications you as to experiment with wireless networks a general so for example also with sensor methods and stock and lessons and a PhD student I had to invent the problem so this is my project and working on that today Allen et and talk to you about this a subset which is this 11 here which are and they're going to tell you what can and finally I and 1 of about some application so what can you do with this thing and maybe kinds some more that to now I wanna step all in make once the bank and then I don't know where we have provided you put 2 all but in the last years of some really fast development so now there are some very good hardware platforms although we just you need be and 210 from the pedals and the entities and this is hot picaresque later on so that means that's not really an affordable chief hardware and which we call for also my mom stuff like that and then on the other side we have the sum of the parts which I labor you radio because I use purity for myself and then to the today we already heard for example for which is using SIMD instructions really speeds up the whole computation process by this vectorized instructions and then another thing a lot and just show this a synchronous messages where you can really switch back and forth between stream-based and packet-based processes and so that means that you can easily implement a real communication system as opposed to just hacking in some physical layer and yet and quality of his all of the reference design of not implemented in which the not to some blocks that also extended the whole framework from the the you out all this text 3 blocks for example and if we had add this together also all this that we now have the tools at hand to implement some state of the art communication standards and I think somewhere I know that there are some active projects for and the radio but which are BT Journal was the activity the 98 and I am working on this Wi-Fi so since you have the ability to implement some state of the art communication standards and since you can really been a whole communication system
I think that the software defined radios also now interesting not only for and this physical layer guys there are to be interested in their signal processing receiver design but also as a computer scientists or some guy was working on the upper layers who might be interested in implementing the protocol on top of the standards or who might look for input data for simulations always concerned about security and privacy issues of of this of this method so I think that with all these improvements in that you can somehow and connect these both amazement this of refined radius uh quite well and today I wanna show how I think you could do for the example of the universe that talk to In the beginning a cable but that's just to give you a very
quick idea was and what we're gonna of all so that their suspicion that cost out there could be some radio module and say that if the guy in the front part just realize is that there's a traffic jam packed then he has the possibility to communicate this to all the other course around him and god and you guys on the other could for example pick up this information and bring it to someone in the very back so that means that you could make driving more safe because he's already alarmed that there is a chem and then you could maybe watery and crashes are on on the others and you could make it more efficient by proposing an all route if you have the possible because this is an and maybe you also want to include sterile science into this whole thing
and yet all of the people cannot ideas what you could use these networks for so they started to work on that and came up with those of the standard in 2011 and also they they reserve some spectrum for exclusive use for ITS applications so intelligent traffic systems so and this spectrum is in the fight or 90 years then so be delightfully interested in that because it's really spectrum scarcity know and to have some dedicated father in value and what they did is the colon they can they to Wi-Fi normal Wi-Fi 11 OK or achieve which most of the electrons are currently operating and and just make some very slight adoption so what they did to this the double all the time these that means that your brain especially time domain but it's more narrow in frequency domain so as opposed to 20 units and the way you normal Wi-Fi popular over right it's that has a 10 meter expanded and from from the economic point of view this is pretty cool because you can just reuse your wife 2 and and divide the quot point to the so that everything gets a crisis so in that case and also for almost all the defined radio wonderful you that's also pretty cool because this change in time just means you change the sampling and here but there there's are some of these problems arise with this because like I was actually intended to operate in indoor environments like here for example some and now if you put this life across in your car and driving around on the free rein in Germany maybe 400 meters polymers because then you don't really know what happens when we actually you try to find that all
the Boston at the expense of particle size and then we also have to lead to some normal life and cards and change the around in the kernel and some part supported to interoperate so as we could come up with some experimental and devices so these 2 I have also 1 of those with me today and here are driving on the freeway and
of the interest was happens when there's a drop in between these 2 classes in the case for example and stuff like that but all these all these kind of prototypes that there's the limitation that and and you you just get very basic data out of them so that you can send a frame and the other you see that you picks up or not but if it did not work you know what happens so if you're back in the lab and try to make some sense of the data and you might easily run into problems so I guess so all idea was to use all 3 find radius for
that and you know maybe you interesting for instance uh I started to work on 1 and implement this 1 the transceiver and
currently currently it looks like that so I I I tried to to fill in decided very very late because computer scientists are pretty used to this layer of communications thank you may know beyond the solar system and then it means that you have the hardware the very bottom of physical layer than some MAX stoppages or somebody the MAC address and all the this and the interface way can connect to suggestively insert data and into the flow graph and they also needed to already talked about your article blocks today and I also make use of them so the whole of the EM stuff this is the need for example in the physical layer blocks of the symbol of the and transceiver in there and I am I developed this when Martin was working on this so thing and implementation and now I obviously also want to kind of integrate this and I already did it for the transmit side so the transmit side is now a completely using Martin's design but not they're receive site and and not yet and I also have it here and we can have a look at this if you're interested so so this is already familiar with what is it's already orders and on the bottom if it has the very same designed so that you can if you the overflow room then you might use these symbols them if you are already familiar with new regular references on again and I II I created some of the modules to connect to that to make life a bit easier in this for example of i shock module so well and you can attach Wireshark and use your life what's going on you get and the french and even annotated with that of general and stuff like that if you on the and and once was company's offices and make use of the PGA OK so at the very at the very top you have this application so they can see something into the flow graph to actually transmitted for example and I have an example for that how
easy that is so with a with only 6 lines of Python code you can injected at packet for example and send some sent some packets all there that you can have received your uh with your life apart so in in that example I used way short message spherical which is a protocol for most it by standardized biological III and maybe this way traffic information or also safety messages might be a distributed and make your networks and you can generate those frames and maybe distribute your own traffic information I know and whatever and we really easy with just like to the socket raise your you will pick up and instance of friend and yeah we we be tried this was quite some hardware so with all the hardware precise we have for 11 g and also we tried some some some wife a constant that assume that this this OK but then I also talked about
the limitations of that because that's what people are so very often and I mean we have the the advantage of its doing everything on the CPU so it's really easy to hack and we can play around with that pretty easy but can be the disadvantage is that you get some delay and as I said you can connect this thing to the TCP IP stack for example and then the easiest thing to do is you can just think the other device all of you and you will connect just use the single command and send something back and forth between the user pianists on and also normal and here we added 100 milliseconds delay artificially but actually it's nothing I know it's not very exact way to measure the labor the point I wanna make use of all the orders of magnitude so with this system we are in the low millisecond scale about what a lot of the days are on that no if you wanna meet the timings of normal Wi-Fi signals then you have to get to the microsecond scale so that means with the support you you will not be able to support and regressors and includes a sense this is a mechanism where you research the channel created the actual transmission or you will not be able to send an acknowledgment in time because they would have to have the 2 but the different space which is around 32 by pressing for the case and there's also a duration view that then that specifies a certain amount of time that should be shown block the channel you know for the actual frames physical quantity and 1 so so this is something that I think will here we have used this identical words and they have the descendants of life that another thing that has happened is that missing again that I think and that can get we can get working as carrier
sensing and channel access and then I talked with them under the and in Miami last year and they already mentioned today that they have an FPGA implementation for channel sensing and and solution that will be and we were working on that and what we are currently doing this you can feel it your wife I frame on the FPGA of the user few and then the user view and then this is due in channel sensing for you it has an easy state machine you can annotate for some small towns and all of that and then you really can come down and to the microsecond in that example i here it's just the pollen levels and then we had 1 years of university in a rating noise then we switched it off and another user p which was sensing the channel then added some very small gap that you wouldn't be able to to to manage on the CPU and then send out the actual of the emperor and will also received this friend with another life right so so that works basically but I still have some features this is mainly because I'm really bad in FPGA programming and I'm currently trying to get users so it's not working a 100 per cent knowledge having really under compliant but I think we're on the way and I hope we will manage that OK so the last part
I wanna talk about some applications and some of the cases from the perspective of a computer science because and of obviously since we now have a nice yard and you all the advantages like you know everything about the signal when it got wrong and what happens up like that but there are also some some common things I guess you could do on the on the upper layers and 1 of us is and for example passing and yeah this is this is a form of penetration testing that means you send as some kind of a random collider it's simple frame or whatever and then you see what happens to the device father actually had planned to do that but when I was working on the transmitter than I am yeah at some point I realized that it was constantly and breaking the driver while my wife about and I had to rebuild all the time and I was pretty annoyed about that and did not make it committed because it was obviously not working and then someone someone with a month ago I thought that this was actually very good to have this as a result of now and trying to reduce it but it's it doesn't need to be there isn't there yet but I think this is something that could you know you might you you could do is talk about all the so and then the monotonous there's also and some other guys in my group all working on this this privacy and Figure fingerprinting techniques so that means that your basically want to indentify uh a center I want to make the tracking more disclosed his identity or stuff like that and there are other approaches the from from the physical layer guys they often look at how teachers or some characteristics of maybe animal from another of the device you know there are some variations and stuff like that in the computer science lies or more of the higher layers and look at traffic patterns and when needed to communicate with what the target was a packet size or maybe look at magnificent that advice and I think with and as are you can get somewhere in between and can try something you because maybe you you can and learn about some findings of the of the circle of or maybe also the driver because not everything that's think of these user may procedure is defined really really except in the status so there are always some uh something that our implementation specific and maybe you could use this this is an additional information to to learn something new or to the city the also more robust to the and and the last thing that we are currently working on and where I think as a risk the and this is to enable more realistic simulations which is absolutely nothing to do with suffering from great but and every we in our group we are also have never simulator which is able to simulate large-scale behavioral networks and then you need some input for the simulator like and that's that's a something packet our approach of for example and on the other hand on the other side there are some physical layer guys that were riding around with some general solace and have real precise measurements of all of them and learn how the channel Jason look so you have some maybe tapped-delay line models or they have some coherence time whatever that you can this resource directly into into urea simulator you need a step in between and I think maybe with a new radio and then subdivide you can you can do that as a yes and you regular has also incorporates a channel you could parametrize this general models with some data that you already know that you learn from the guys who were driving around the channels some you may be can but the same day I mean and then do some simulations in your radio and come up with some moralistic error curves that you can then use in Europe India simulated some maybe some applications that are more highly OK so so that's it from
my side now think we wanna wrap this up so
we have this quality and consumer implemented and that that it's easy to use in this model and extensible and he and had told his shows some possible applications maybe you can come from something OK
finally I have some other projects and currently working on is of the essence decoding media data services and also some and signifies files according due to their and forestry projects I'll also have some demo stuff with me so if you are interested just you can just talk to me or you can have a look at the OK so thanks for your attention it could be that the that's probably you're aware of that will be used to yeah it's the the final standardized the physical is is there is some standard coming of the link in the world so there's this that ITS 5 and then there is this year's RTE wave the all of and use 11 yes the physical and MAC layer on top of and both give recommendations on how to use this was connected so it's no definite um not positive that I mean this for example the distribution of you know exactly yeah so I mean you can also run to view the theory on top of that before this traffic applications you have a different of that you have Quality of Service but different from the of the safety you have more of multimedia streams and stuff like that so they build up on on on 11 p as a and if you think the methylation on the left and use would have no print and not of this approach is because they think if you really want to see all the time constraints you have to move out of the a lot of stuff to the FPGA and then that basically means change and hold the text of the village and you even you're using these are expressed in the form of a computer almost like a binary managers explains why and how to solve problems it's a half reactions EEG sends out 3 juggling act and that process is a real active recently and I suppose will happen in the user can this at of the west and they were