Friday, March 24, 2006

Max HSDPA Throughput in EURANE = 1.3Mbps

I think have similar observation of the throughput



Greetings,

I have simulated an HSDPA cell with two UEs but only one active CBR source sending at 4Mbps. The input trace file is the same as the idealtrace but I changed all CQI values to 29 in order to achieve maximum throughput. However, the throughput was saturating at only 1.3Mbps !!
Can someone clarify why? There might be a configuration parameter limiting the number of codes or coding rate??


regards.

AMM

source

Thursday, March 23, 2006

TCP Window

The variable "window_" in ns2 corresponds to "awnd" in the literature.
Using this variable you can set an upper bound for the TCP window at the
source. So, if you wish to "set the TCP maximum windows size to 50",
just
set window_ to 50 in your tcl script.
Note that "window_" is binded as "wnd_" in the c++ code
(tcp/tcp.{h,cc}).


source
Had some problem in calculating the throughput from the trace file. Still searching the method to implement flowmon.

I came across posting where it explain that TCP adjust its sending rate when there is a congestion in the link.


TCP adjusts its sending rate using a congestion control algorithm

Take a look at the following paper, it could help you

Van Jacobson, “Congestion Avoidance and Control,” in Proceedings of ACM
Sigcomm’88, Stanford CA, August 1988, 314-329.

Best Regards

Alfredo

---------------------------------------------
Luigi Alfredo Grieco, Ph. D
Assistant Professor
DEE Politecnico di Bari,
Via Orabona 4 - 70125 Bari, Italy
Ph. +39-080-5963301
Fax +39-080-5963410
http://www-ictserv.poliba.it/grieco


-----Messaggio originale-----
Da: ns-users-bounces at ISI.EDU [mailto:ns-users-bounces at ISI.EDU] Per conto
di mehri rajayi
Inviato: martedì 12 aprile 2005 11.11
A: ns ns
Oggetto: [ns] how create tcp connection with spesific rate?



i want to create a tcp connection with ftp traafic sourse, with this
parameter (rate:128Kbps pktsize:1000byte ) but tcp hasn't rate
parameter. I set packetSize_ to 1000 but in trace file PKTsize is equal
40. can you help me.


-source-

Monday, March 20, 2006

Link

Met with the supervisor on 16th March. Wrote a progress report to submit to the supervisor. The report mentioned some literature reviews and preliminary simulation works. Supervisor kind of agreed with the idea and ask to come out with some simulations for the next meeting.

Things to do:
Read and understand.
Build some simple simulation scenarios.
Check with 3gpp standard for QoS


Link

Wednesday, March 08, 2006

RED again..

I think I solved the problem. Actually it is not a problem.

I think in ns2.28 the paramater "Queue/RED set queue-in-bytes_ true" is set to true by default. In ns2.27, the parameter is set to false by default.

I want the queue size in term of packets. To over ride this just add the following parameter in red.tcl script when using ns228.

"Queue/RED set queue-in-bytes_ false"

I think this is also apply for ns229.

Any reason why we want to monitor the queue in bytes rather than in packest?

Tuesday, March 07, 2006

Windows reads linux partition...

Click here for the website

Why use simulator ?

Simulation is often based on random events.

Therefore, if you want a real time implementation, then if 2 events are
seperated by minutes, then you would just have to wait. Ns-2 is
event-oriented, and therefore if there is nothing to do between 2
events, then the clock is incremented, and you do not have to wait.

In the other hand, suppose you have a large simulation with a lot of
users. In case a complex treatment has to be done at each user's
equipment, then the computer would have to do it all, with NO real-time
guarantee !

Thirdly, ns-2 is a supported by a whole community, and freely available;
if you can find a real-time simulator please let me know, but I do not
see any.

-source-

VoIP...

Since many VoIP codecs send data at the constant rate, you can use normal UDP/CBR application to simulate VoIP. You have to set appropriate parameters so that the rate and the packet size correspond to the codec you use.

Friday, March 03, 2006

RED queue

I have some problem while simulating a simple scenario using 3 TCP sources with RED queue at the bottleneck lick. The tcl script was obtainde for this website. The result that I got is totally different from this document. The queue just grew beyond the limit of 100. The same thing is happening when I rerun the simulation script using UDP protocols under Constant bit rate traffic.

Steps to find the root the problem
1. Recompile ns-2.28 and run the simulation again
2. Run the simulation under ns-2.27
3. Or if this does not work run under ns-2.29
4. Try running the simulation on Fedora

Wednesday, March 01, 2006