Is GFSK modulation implemented in NS3 so that Bluetooth Low energy physical layer can be developed?

[Praveen Kumar]

Hi all, 

I am new to NS3 and facing some problem. I wanted to ask if there is GFSK modulation implemented in NS3 so that BLE physical layer can be developed. Also, is it possible to implement BLE physical layer using NS3? I also needed to ask if there are any point-to-multipoint links or channels in NS3?

Any sort of guiding or help will be highly appreciated.


Thanks 

[Tommaso Pecorella]

Hi,

please study the documentation and how the channel errors are implemented in ns-3.

GFSK is not implemented, but you don't need it. All you need is an error model that takes into account the modulation and coding scheme. In other words, for ns-3 you need a net bit error rate probability, not a symbol-level error probability.

Point to multipoint... check the spectrum model (and all the wireless models).

have fun,

T.

[Praveen Kumar]

Hi Tommaso,

Thanks for your response.Also , can the error model be used for developing the physical layer in NS3 or will require any other things? 


Thanks again

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Praveen Kumar

Fourth year undergraduate student

Department of Electrical Engineering

IIT Kharagpur-721302

West Bengal, India

Phone no- +91 7407654496

Email- prav...@iitkgp.ac.in

[Tommaso Pecorella]

Hi,

please study the ns-3 documentation.

Also, please clarify what is your goal (clarify to you, not to me). ns-3 is a network level simulator, and it is not meant to simulate a physical layer. it uses models to simulate the phy. I.e., the PHY is (usually) just a BER formula.

If you want to simulate the BT PHY layer, then ns-3 could be not the right tool.

T.

On Wednesday, July 1, 2015 at 3:45:09 AM UTC+2, Praveen Kumar wrote:

Hi Tommaso,

Thanks for your response.Also , can the error model be used for developing the physical layer in NS3 or will require any other things? 

where

Thanks again

[Praveen Kumar]

Hi Tommaso,

Thanks for the response. And at the same time, i am really sorry if my doubts sounded weird or unclear to you. But what i want to do is to simulate the different bluetooth nodes with mobility patterns installed and check the RSSI Values. Since, in prior checking i found that there is no BLE module in NS3, it seems as if to implement the different protocol stack. Also i wasnt sure about how to find this error rate model and link it with the other layer like link layer of bluetooth.

Sorry for any inconvenience but at the same time, it will be really thankful if any sort of help or guideline can be provided.


Thanks again

[Tommaso Pecorella]

Hi,

don't be sorry, your doubts are unclear, but not weird.

If your goal is to measure the RSSI values when nodes are moving, then (sadly) ns-3 isn't your tool. This doesn't mean that you shouldn't use ns-3, it's just that the RSSI is an input for ns-3, not an output.

Let me clarify with an example. If you have node A and node B, and node A sends a packet to node B, the receiver node will calculate the RSSI according to a channel model (e.g., Friis). Then it will calculate the BER (usually with a formula, sometimes with tabular data), and from the BER it will draw the PER. Then a random number is drawn and the packet is either considered error-free or with errors.

Now, as you can see the RSSI is [almost] an input. If you need/want to work with channel models and so on, Matlab is more appropriate. As a matter of fact the LTE BLER curves are generated by Matlab, then imported as tabular data into ns-3 and used to calculate the PER.

On the opposite, if you want to evaluate the BLE performances (transfer rate, QoS, etc., then an ns-3 model will be defintiely needed (and indeed, it would be very interesting).

I hope this can clarify you some points.

Cheers,

T.

[Praveen Kumar]

Hi Tomasso,

Thanks for being patient and replying. I had one more last doubt. Suppose i have to develop the whole BLE stack including physical layer, link layer, l2cap,GATT, GAP, how can i take help from NS3 modules. Earlier, i was taking reference from Wifi or lr-wpan. But it seems that i am getting lost and lost in the different models of either wifi or wpan. I was tring to analyze the packets and all, but it seems a lot of things are different. If you have any idea or suggestion about this, please show some me guidlines.

Also RSSI is input parameter but won't be there any attenuation if the receiver or sender node moves and that attenuation or final signal strength i have to get from the simulation.


Thanks again

Praveen

[Tommaso Pecorella]

Hi,

I'll reply in reverse order.

Yes, mobility and interference will change the RSSI dynamically. Still, its correctness is relying on formulas.

About implementing the whole BLE stack... I don't want to turn you down, but it's going to be a HUGE effort. That's why I am suggesting to study these modules. You can grab ideas and evaluate the amount of effort you'll need.
About how to proceed, there are a few posts and how-to, but the main suggestion is: design it. Write the data structures and the APIs (the ones from the standard). Then develop the message processing parts.
Again... plan everything carefully. It won't be a walk in the park, and existing modules can be useful only to learn some tricks. Your code will be 99.5% new.

Have fun,

T

[Praveen Kumar]

Hi, 

Talking first about the RSSI, shouldn't be it same in case of wifi or BLE or wpan signals as it depends upon propagation parameters? I took reference from this https://groups.google.com/forum/#!topic/ns-3-users/trUK0XOswCU . Also, it must have been calculated using some formula in NS3.

Anyways, thank you a lot for being patient and responding the whole time. Regarding BLE, its stack seems complex in itself and so not sure how their message processing parts can avail any benefit from network module of NS3.

Thanks again

ᐧ

T

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[Tommaso Pecorella]

Hi,

the RSSI should be the same, more or less (it depends on the frequency). What will be totally different is the BER calculation from the RSSI.

Have fun,

T.

[faheem awan]

Hi,

It's been quite an old post but......

Were you able to implement entire bluetooth stack?