[Ns-developers] GSoC: WiMAX Projects

[Mohamed Amine Ismail]

Hi Nitin,

> estimated error. Do you think implementation of such a scheme in ns-3
> wimax module will be feasible?

I think such a mechanism is very interesting for the WiMAX module, however, in 
the current version of the code there is no error model implemented yet. You 
can maybe implement a basic error model (Gilbert model?)  and then design and 
implement  a mechanism which computes the optimal size of the PDU based on 
the estimated error.

Thanks
Amine

On Tuesday 31 March 2009 21:31:05 Nitin Dua, IIT G wrote:
> Dear Amine,
>
> I had some queries regarding the mail below which you sent a few days back.
>
> > Hi,
> >
> > I'am Mohamed Amine ISMAIL a Ph.D student at the INRIA. Actually I am
> > working
> > on the wimax module for ns-3.
> >
> > The current WiMAX module provides the main functionalities of the WiMAX
> > standard. The core part of the MAC layer includes the generation of the
> > MAC
> > frames (in TDD mode) and the construction and transmission of the key MAC
> > control messages (DL-MAP, UL-MAP, DCD, UCD, RNG-REQ and RNG-RSP).
> >
> > The Link Manager component at the SS and BS side handles the network
> > entry and initialisation procedure that a new SS follows upon entering
> > the WiMAX network. This procedure includes the scanning process  and the
> > initial ranging process.
> >
> > Once the network entry process is successful, the SS is assigned with a
> > set of
> > connections. This includes two connections for the management messages
> > and a
> > number of transport connections for the data traffic. Both SS and BS
> > maintain
> > their own connection managers. For the BS the connection manager handles
> > the
> > creation and management of all the connections associated to SSs
> > registered
> > with the BS. For SS the connection manager manages connection associated
> > to
> > the SS. The SS Manager component is maintained by the BS to access all
> > the SSs currently registered to BS.
> >
> > The service flows are set up during the installation of the application.
> > Once
> > registered with BS the SS then requests for creation of an already set up
> > service flow from BS, and BS then creates the service flow, registers the
> > QoS
> > parameters associated to it, and allocates service flow to SS. This whole
> > process is done through the exchange of DSA (DSA-REQ, DSA-RSP and
> > DSA-ACK) messages.
> >
> > The module supports all four scheduling services. Each service flow is
> > associated to exactly one transport connection and one scheduling
> > service. The QoS parameters associated to a service flow actually define
> > the scheduling service it belongs to. Standard QoS parameters for UGS,
> > rtPS, nrtPS and BE services, as specified in Tables 111a to 111d of the
> > 802.16e amendment, are supported.
> >
> >
> > The current WiMAX module provides two different versions of the PHY
> > layer. The first one is a basic PHY implementation which simply forwards
> > bursts received by the MAC layer ignoring any underlying PHY layer
> > details. The second one is a more complete OFDM PHY layer, it uses
> > external
> > mathematics and signal processing library IT++ together with the LAPACK,
> > BLAS
> > and FFTW libraries. no propagation/error model has been considered, hence
> > one
> > of the future works is also to add support for a propagation/error model.
>
> Is it that the optimal size for the PDU is not considered at all. I came
> across this paper
> http://ieeexplore.ieee.org/iel5/4483765/4488105/04488131.pdf?arnumber=44881
>31 which talks about finding an optimal size of the PDU based on the
> estimated error. Do you think implementation of such a scheme in ns-3
> wimax module will be feasible? I am sure there may exist other tested
> schemes. I would like to integrate such fragmenting/defragmenting PDU
> techniques in ns-3 over this summer. Please send me any resources you are
> aware of.
>
> > Actually we are working on an IPCS classifier. The classifier  is used to
> > map
> > the incoming packet to the appropriate service flow based on a set of
> > criteria. The service flows are created at the scenarios setup and a bind
> > function is developed to associate an IP traffic to a service flow based
> > on
> > the IP src,IP dst, protocol, port src, and port dst. The IPCS analyses
> > the headers of the incoming IP packets from the upper layer and map them
> > to the
> > appropriate connexion.
> >
> > An other ongoing work is the development of the pcap tracing function for
> > the
> > wimax packets.
> >
> >
> > The module currently lacks the implementations of :
> >
> > - fragmentation/defragmentation of PDU(s)
> > - dynamic burst profile management
> > - Propagation/error model
> > - more sophisticated algorithm for the scheduler
> > - more efficient algorithm for the bandwidth management mechanism
> >
> >
> >
> > Regards
> > Amine
>
> Thanks & Regards,
> Nitin