1. Install dhcp server
   sudo apt-get install dhcp3-server
2. Install firestarter
   sudo apt-get install firestarter
3. Create symbolic link for dhcpd. Need to do this because firestarter looks for dhcpd, while in Ibex there’s only dhcpd3.
   sudo ln -s /usr/sbin/dhcpd3 /usr/sbin/dhcpd
4. You might need to assign ipaddress to the network interface card that connect to your LAN.
   sudo ifconfig eth0 192.168.0.1
5. Run firestarter
6. 
7. 
8. 
9. 
10. Just connect your other pcs to the hub/switch

Note:

1. I used Intrepid Ibex.
2. I connected the pcs through cable. Haven’t tried this method for sharing internet connection over wireless (adhoc).

emobile modem

I had a problem connecting to internet using huawei 3G modem D02HW inUbuntu Intrepid Ibex before. The modem was detected, I already set the gnome-ppp to use this setting:
username: em
password: em
phone number: *99***1#
Deveice: /dev/ttyUSB0
Type: USB Modem
Speed: 460800
Phone Line: tone
Volume: High
InitString: init2=>ATH0E1
but it still couldn’t connect to the internet. It kept saying waiting for prompt and then permission denied on /usr/bin/pppd bla bla bla.
Here is the solution: change the user privilage in System -> Administration -> User and Groups -> Unlock -> Insert your password -> Properties -> User Privileges -> Check “Connect to internet using a modem” -> OK -> Logout -> Login -> Try connect again, it should be working now.

Tokyo tower

Japan is not only famous of its manga and anime, but also of the advance of technology. One of the reason of this advance is because of so many researches conducted in universities and companies. Recently I just found out about the reason why students and lecturers in Japan willingly conduct so many researches. Not only to add more entries on their curriculum vitae, but also because they want to go abroad. As you may know, there are so many international conferences about technology. And since it’s international scale, most of the time it’s held outside Japan. By doing research, they can submit papers, and if the papers passed the review, they will have the chance to go abroad. They also don’t have to worry about the money, because the university will pay for them, everything. For university, money is not a problem. The more papers produced by their students/lecturers, the more famous the university will be.

Researching is like racing here. In a meeting few days ago, my sensei listed the international conferences that will be held next year like PIMRC in Tokyo, VTC in Alaska, and APWCS in Seoul. He encouraged everyone to submit a paper to any of the conferences. Not only the master student or PhD students, but also the bachelor students as well. Even one of my friend who is still in bachelor degree is ready to submit paper to APWCS cause he wants to go to Seoul.

I believe this is one of motivation that universities in Indonesia should have to advance in technology. Especially to ITB, since I heard ITB is planning to be a research based institute. Hopefully more good quality papers are produced from ITB.

For a certain value of time, the bit error rate probability is

where . is the instantaneous SNR on the th channel.

When , and

where (average SNR per channel). So the characteristic function is

Since the fading on K channels is mutually statistically independent

Using inverse fourier transform,

So, the Bit error rate (error probability)

To solve equation above, use integration by parts.
By definition,
which is another way of rewriting the usual

Let .
And by definition

So we have

Let also

So

Probability of error becomes

And somehow the equation becomes

where

So that’s it. Anybody can help me on the last part of the derivation? You can download the pdf version of that equation here.

How to convert videos to psp compatible format:
ffmpeg -i InputVideo -f psp -r 29.97 -b 768k -ar 24000 -ab 64k -s 320x240 outputvideo.mp4

How to convert pdf to image(s):
convert nani.pdf nani.jpg
or you can use ghostscript instead using this script:
#!/bin/bash
if [ $# -ne 2 ];then
echo “Usage: $0 input.pdf outfile”
exit
fi
INPUT=$1
OUTFILE=$2
gs \
-dSAFER \
-dBATCH \
-dNOPAUSE \
-sDEVICE=jpeg \
-r150 \
-dTextAlphaBits=4 \
-dGraphicsAlphaBits=4 \
-dMaxStripSize=8192 \
-sOutputFile=${INPUT}_%d.jpg \
${TARGET}

To be able to execute convert and ffmpeg, you need to install them first of course.