CFP: IJDSN - Special Issue (SCIE Indexed), Deadline: Friday, 10 July 2015

International Journal of Distributed Sensor Networks (IJDSN) invites paper for the special issue on -

"Applications of Cognitive Radio Networks: Recent Advances and Future Directions"

Call for Papers

The demand of spectrum increased tremendously due to the recent advancements in wireless communication technology. This dramatic requirement of spectrum has challenged the current spectrum licensing system and inspired authorities to legalize opportunistic spectrum access. Recently, many authorities, researchers, and hardware manufacturers are working to solve this virtual scarcity issue. Cognitive radio (CR) networks are suitable in this mitigation, by utilizing licensed spectrum opportunistically. CR is rapidly proliferating into many wireless communication fields. Spectrum sensing, spectrum sharing, coexistence, spread spectrum, and MIMO techniques have become areas of concern over the past decade. More recently, many researchers are working in various application areas of cognitive radio networks (CRNs) and cognitive radio wireless sensor networks (CR-WSNs).

Easy steps to install ns-2 in Ubuntu 12.04

For some reason I have started working in ns-2 again and I recently installed ns-2 on Ubantu 12.04LTS. I am writing this blog for the newbies in ns-2. 

Job for Electronics/Communication/Computer/IT Engineers in Samsung

Where: Samsung Electronics, South Korea,
Type: Full-time
Desired Skills & Experience : The ideal candidate will have 8+ years of development experience, knowledge about wireless network protocols and deployment of network software for Linux, ,Android, Windows systems.
Excellent software design, problem solving, and debugging skills.
Experience with system level understanding on Wi-Fi drivers

Qualifications:
MS or Ph.D. is preferred
8+ of professional work experience as a software or system engineer

Postdoc positions at the Faculty of Electrical Engineering

Where:  Czech Technical University
The first deadline is April 11, 2013, but applications sent later may be also considered if all positions are not filled.
Requirements for the candidates: Completed PhD at the time of beginning of the contract, but not earlier than March 29, 2008
At least one journal paper

How to install gcc-3.3 in Ubuntu 9.04

Today I tried to install gcc-3.3 in Ubuntu9.04 in my PC. I followed following steps. I found 2 patches to solve the errors in the Internet.
(NOTE: - means delete, and + means add as in Patch file)

1. Download gcc-core3.3.tar.bz2 and gcc-g++-3.3.tar.bz2
2. bzip2 -cd gcc-core3.3.tar.bz2 | tar xvf -
bzip2 -cd gcc-g++-3.3.tar.bz2 | tar xvf -
3. mkdir build
4. cd build
5. /home/xxxx/gcc/gcc-3.3/configure --prefix=/opt/gcc33 --program-suffix=33 --enable-languages=c,c++

6. If there are errors from /usr/include/bits/studio-lock.h file
then comment the /*#include */
- #include
+ /*#include */
7. If there are errors from gcc/gcc-3.3/include/obstack.h file ("/read-rtl.c:653: error: lvalue required as increment operand")
Change line#423 in gcc/gcc-3.3/include/obstack.h
- *((void **)__o->next_free)++ = ((void *)datum); \
+ *((void **)__o->next_free) = ((void *)datum);
+ __o->next_free += sizeof(void *); \
8. If there are errors from decl.c file
Apply gcc42-patch-gcc-3.3.1_gcc_cp_decl.c patch from ftp.nsysu.edu.tw/FreeBSD/FreeBSD-current/ports/palm/prc-tools/files/gcc42-patch-gcc-3.3.1_gcc_cp_decl.c
9. If there is an error "gcc/collect2.c:1779:/usr/include/bits/fcntl2.h:51: error: call to ‘__open_missing_mode’ declared"
Then, in the line number 1776 of gcc/collect2.c
- redir_handle = open (redir, O_WRONLY | O_TRUNC | O_CREAT);
+ redir_handle = open (redir, O_WRONLY | O_TRUNC | O_CREAT, 0666);
10. make
11. Follow http://www.mjmwired.net/resources/mjm-fedora-gcc.html

Few useful commands:
sudo apt-get install gcc
find /usr/bin |grep gcc
find /usr/bin |grep g++
stat /usr/bin/gcc

$ cd /usr/bin
The default gcc version
$ gcc --v

Delete the old symbolic links
$ sudo rm cpp gcc g++

Change the symbolic links to 3.3: (Find where the gcc33 is installed. In this example we installed in /opt/gcc33/bin (we gave the command while installing gcc as: --prefix=/opt/gcc33).

$sudo ln -s /opt/gcc33/bin/g++33 /usr/bin/g++
$sudo ln -s /opt/gcc33/bin/gcc33 /usr/bin/gcc
$sudo ln -s /opt/gcc33/bin/cpp33 /usr/bin/cpp

Check the default gcc version

$ gcc --v

It should show new gcc version.

Problem with NS-2

Problem: Makefile:314 *** commands commence before first target. Stop.
Solution: DO NOT use tab or copy/paste spaces from previous line when you add .o in makefile. Use only space.

NS2 installation problem on Cygwin / NS2 installation problem on Windows7

I installed latest version of Cygwin and tried to install and run NS2, but it didn’t work. I check this site and found following information. http://nsnam.isi.edu/nsnam/index.php/Running_Ns_and_Nam_Under_Windows_9x/2000/XP_Using_Cygwin
I tried to search the solution on Google but couldn’t find exact answer. So, I am posting here. This may be useful to you.

The current version of Cygwin 1.7.x breaks some programs, including ns-2. Presently, there is no working version of the ns-allinone-2 series that works with Cygwin 1.7.x

Although, the above site says there is a "legacy" installation that will allow you to install Cygwin 1.5 series and then install ns-allinone-2 package. But, when I tried to install legacy, it didn’t work.

Fortunately, I found old version Cygwin 1.5.x in one of my friends’ computer. Now, it works perfectly.

Suggestion: try to get old version of Cygwin
Command to check version of Cygwin (it’s same as in Unix): uname –srv

Good luck

NS2 (Network Simulator) resources

A link that answers you all.

http://www.matlab.nitech.ac.jp/~khpoo/research/ns2.html

Some other links

http://hpds.ee.ncku.edu.tw/~smallko/ns2/ns2.htm

Advice to the graduate students

http://www.cse.psu.edu/~yuanxie/advice.htm

Why queue if λ/μ < 1 ?

In Poisson distribution, why there is a queue even though λ/μ < 1. Where λ is an arrival rate and μ is a service time?

Because λ and μ are the average (or expected) value of distribution. It doesn’t mean that in every t second a customer arrives into the system. Inter-arrival (the time between consecutive events) time are exponentially distributed and arrival rate is Poisson. It means the time between two consecutive arrivals are different.
In other words, even though λ/μ < 1, two or more customers may come to the system at the same time and system can serve only one customers at one time. So, we need queue. For example: average arrival rate (λ) = 10 customer per hour, average service rate (μ) is 15 customer per hour. It means λ/μ <1. However, it follows Poisson distribution, so, two customer (or in the worst case, all the 10 customers) may come at the same time. That’s why we need queue.

How to measure packet loss rate, jitter and end-to-end delay ?

Here is the nice script for measuring packet loss rate, jitter and end-to-end delay in the prof. Chih-Heng Ke's website. 

http://140.116.72.80/~smallko/ns2/tool_en.htm

How to measure the throughput, packet drop rate, and end-to-end delay for UDP-based application over wireless networks is given here

http://hpds.ee.ncku.edu.tw/~smallko/ns2/wireless-udp-1.htm

This fellow has a good collection here:

http://lovefei.com/?p=19

BSS vs. IBSS

There are two service sets in IEEE 802.11 standard. The basic service set (BSS) for the infrastructure mode and the Independent Basic Service Set (IBSS) for the ad-hoc mode. 

The BSS is a single access point (AP)  together with all associated stations with the AP. In the infrastructure WLAN , communications can only take place between the AP and the other members of the BSS. 

In the ad hoc networks, all of the stations those are within each other's transmission range is called an IBSS.

NS2.31 NAM problem - "[code omitted because of length]"

Problem: While executing NAM in NS2 following error appears. 

nam:
[code omitted because of length]
: no event type or button # or keysym
while executing
"bind Listbox {
%W yview scroll [expr {- (%D / 120) * 4}] units
}"
invoked from within
"if {[tk windowingsystem] eq "classic" || [tk windowingsystem] eq "aqua"} {
bind Listbox {
%W yview scroll [expr {- (%D)}] units
}
bind Li..."

Solution: 

1. Download  "tk-8.4-lastevent.patch" patch file from http://bugs.gentoo.org/show_bug.cgi?id=225999
2. Save the file in tk8.4.x floder (remember that there could be tk8.4.14 or tk8.4.18)
3. Patch the file with this command

                         patch -p1 < ./tk-8.4-lastevent.patch

    4.  install again (with ./install command)

Now it works perfectly. 

(If there is a problem on patching, change -p1 to -p0. )

Installation of Cygwin and NS2 on Windows

The best open source tool for network simulation is NS2. The first step to learn NS2 is to it. Cygwin gives linux like environment on Windows. Here is the step by step procedure how to install NS2:
 
                  http://personals.ac.upc.edu/rzilan/ns/2_NS2InstalCYGWIN.pdf

Some other useful links for NS2.

1. The Network Simulator: Building Ns, http://www.isi.edu/nsnam/ns/ns-build.html
2. How to Compile Ns2 on Windows Platform, http://www.isi.edu/nsnam/ns/ns-win32-build.html
3. Ns Manual, http://www.isi.edu/nsnam/ns/ns-documentation.html
4. Tutorial for the Network Simulator “ns”, www.isi.edu/nsnam/ns/tutorial/index.html
5. Tracegraph Program Download Page, http://www.geocities.com/tracegraph/
6. NS by Example, http://nile.wpi.edu/NS/