(Developed at Department of Computer Science & Engineering, Indian Institute of Technology, Kanpur, India)
The Enhanced Network Simulator (TeNs), is an extension of the existing popular
networking simulation tool - Network Simulator (See NS
homepage for details, tutorials and downloads). TeNs is an attempt to
address the deficiencies of ns in the modeling of IEEE 802.11 MAC layer
protocol, which is highly simplified in the original ns . Apart from a more
realistic implementation of this, it also incorporates additional features like
multiple interfaces support for mobile nodes, a static routing protocol for
wireless scenarios, and also features inclusion of simple directional antennas
(see the section Enhancements and Modifications to NS for details). The utility
can be seen in the simulation of long distance links, as illustrated in the
sample scripts later in this page.
1 Instructions for Installation
- Download the NS-2 package
ns-allinone-2.1b9a-gcc32 (compatible with gcc32), from here.
You could alternatively use your own source. TENS has been installed with
ns-2.1b9a, so preferably you should have this version
- Download the changes made to
TENS from here.
- Follow the instructions
contained in the README of the package (its the same as available in the
original NS package from NS homepage). After "./install",
execute the following steps:
- Untar the TENS
changes in the .../ns-allinone-2.1b9a/ns-2.1b9a directory. Inside the
TENS directory, execute the copy.sh script to copy the relevant files into
the NS2 directory. If your TENS directory is not in the
.../ns-allinone-2.1b9a/ns-2.1b9a directory, you will need to change
$NS_DIR(in copy.sh) to point to the ..../ns-allinone-2.1b9a/ns-2.1b9a
directory.
- After running the copy.sh
script, go to the ..../ns-allinone-2.1b9a/ns-2.1b9a directory and make
the following changes to the Makefile:
- First of all check the
Makefile and replace any alien path existing in it, with what you think
should be for your installation. This may not be required if "
./install " has properly created the Makefile or not.
- change variable CPP in
the Makefile to " CPP = g++ "
- change variable NSE
in the Makefile to " NSE = nse "
- make variable BUILD_NSE
empty, i.e., " BUILD_NSE = "
- Search for the line
containing " mobile/antenna.o mobile/omni-antenna.o \ " and
replace it by " mobile/antenna.o mobile/omni-antenna.o
mobile/dir-antenna.o\ "
- Search for the lines
" aodv/aodv_logs.o aodv/aodv.o \ aodv/aodv_rtable.o
aodv/aodv_rqueue.o \ " and add the lines "
wlstatic/wlstatic_logs.o wlstatic/wlstatic.o \
wlstatic/wlstatic_rtable.o wlstatic/wlstatic_rqueue.o \ " before
it.
- Search for line
"mac/phy.o mac/wired-phy.o mac/wireless-phy.o \" and add
"mac/wp2p-ll.o mac/wp2p-mac.o mac/wp2p-phy.o \" after it.
- Search for NS_TCL_LIB
declaration and add "tcl/lib/ns-stdma-lib.tcl \
tcl/lib/ns-stdma-link.tcl \" to it.
- Now, do " make
clean " and "make depend"
- Then execute make and you
are done. In the end export an additional environment variable -
"NS_ANTENNA_FILE" with its value being the path where the
antenna radiation file is being stored.
$export NS_ANTENNA_FILE=...../ns-allinone-2.1b9a/ns-2.1b9a/mobile/antenna.txt
The Changes in TENS fro NS-2 and in subsequent versions in TENS1.1 and
TENS 1.2 are given below. These may serve as a starting point for anyone
wishing to learn about the code level changes made to NS-2 and further extend
NS-2
ChangeLog for TENS1.0 - A file wise
description of the changes made to NS-2 code
ChangeLog for TENS1.1 - A file wise
decsription of bug fixes and feature additions to TENS1.0
ChangeLog for TENS1.2 - A file wise
decsription of bug fixes and feature additions to TENS1.1
- Multiple interface
support added
- Static Routing
implemented for wireless nodes
- Co Channel
interference added
- Adaptive data rate
support for 802.11
- BPSK Modulation Scheme
Added
- Directional Antenna
support added (More radiation pattern added in TENS1.2)
- Channel Number made
configurable
- Addition of ARP
entries through script
- 2-p protocol for point
to point link added
- Several MAC parameters
like RTS Threshold, Capture threshold made configurable. See the tutorial for full details.
In this section we provide a quick tutorial on the new feature additions
and their usage. Please note that this tutorial assumes that the reader is
fairly acquainted with NS-2. Extensive NS-2 tutorials can be found at the
following links:
Marc Greis's tutorial
NS for Beginners
NS Manual
4.1 Configuring
Network Components
4.3.1 Setting up Multiple interfaces
4.3.2 Attaching a directional antenna
4.3.3 Setting the Transmit Power
4.3.5 Capture Threshold Setting
4.3.6 Carrier Sense Threshold Setting
4.3.8 Modulation Scheme Settings
4.3.9 Frequency settings and Loss factor
4.5 Setting up
parameters for MAC
4.7 Using the 2P
Iimplementation
4.7.1 Link Layer
Configurations
4.7.2 MAC Layer
Configurations
4.1 Configuring Network Components
A mobilenode consists of network components like Link Layer (LL), Interface
Queue (IfQ), MAC layer, the wireless channel nodes transmit and receive signals
from etc. At the beginning of a wireless simulation, we need to define the type
for each of these network components. Additionally, we need to define other
parameters like the type of antenna, the radio-propagation model, the type of
ad-hoc routing protocol used by mobilenodes etc. The following snippet of code
will usually be there. Look at the comments for a decsription of the variable
and changes from NS-2.
|
set
val(chan)
Channel/Channel_802_11
;# channel type, NS-2 used Channel/WirelessChannel |
4.2 Main Program
The main programme can be started in the same manner as NS-2, when a new
simulator is started, trace files are opened, creation of GOD object and
creation of topology. All these remain unchanged in NS-2. So, the following
code will start the script. Also, higher layers implementation remain
unchanged. So, one could attach a CBR, FTP or a TCP connection with a node.
4.3.
Configuration of Nodes.
4.3.1 Setting up Multiple Interfaces
Nodes in TENS may be configured to have multiple interfaces. This may be done
by the following line in your tcl script.
|
$ns
node-config -numif 1 |
Subsequent parameter additions for different interfaces can be done by
using the following format:
|
$node
set netif_(<interface number>) set
<parameter> <value> |
4.3.2 Attaching a
directional antenna
Directional Antenna may be created and setup as follows:
|
set a
[Antenna/DirAntenna] |
Width is needed only for type 0. For type 0, the antenna returns a gain
of 1 multiplied by the solid angle, if the node falls inside the cone of
coverage formed.
The following antenna types are also present:
Type 1
HG2424G See
data sheet over here.
Type 2
HG2414P See
data sheet over here.
Type 3
HG2418P See
data sheet over here
Type 4 HG2417P-090 See data sheet over here
Type 5 HG2417P-120 See data sheet over here
Only radiation pattern and gain values are relevant in the data sheet.
If you add a new antenna radiation pattern, please mail in your antenna file
to abagri@cse.iitk.ac.in along
with a radiation pattern graph image or data sheet of the antenna.
An antenna can then be attached to a nodes interface in the following manner:
|
[$node_(0)
set netif_(0)] dir-antenna $a |
The directional antenna module takes its input from a antenna file which is
expected to be in the NS_ANTENNA_FILE enviroment variable. the default exists
in ...../ns-allinone-2.1b9a/ns-2.1b9a/mobile/antenna.txt. The format of this
file is lines of antenna gains for differnet angles and antenna types. This can
be replaced by ones own antennas file where each line has the following format
|
<type>
<angle> <gain> |
4.3.3 Setting the Transmit Power
The transmit power of an interface may be set by using the following:
|
[$node
set netif_(<interface number>)] set Pt_ <transmit power in W> |
4.3.4
Channel Number Setting
Channel Number for a node/interface may be set up by the following:
|
[$node
set netif_(<interface number>)] set channel_number_ <channel
number> |
TENS implements co-channel interference and this should be noted while setting
up channels for interfaces. The co channel interference is implemented as
follows:
If a node is receiving and sending simultaeously on two different channels,
difference of their frequency is calculated and normalized by dividing the
difference by 5e+6. If the normalized value is greater than 5 then Tx power is
reduced to 0, For 4, it is reduced to 20%, 40% for 3, 60% for 4, 80% for 4.
4.3.5 Capture Threshold Setting
Settings for Capture Threshold may be setup for a node/interface may be set up
by the following:
|
[$node
set netif_(<interface number>)] set CPThresh_ <value> |
4.3.6 Carrier Sense Threshold Setting
Settings for Carrier Sense Threshold may be setup for a node/interface may be
set up by the following:
|
[$node
set netif_(<interface number>)] set CSThresh_ <value> |
4.3.7
Rx Threshold Setting
Threshold settings for receiving a packet may be setup different from the
capture packet threshold as follows. Unless, receiving power is less than this
value, packet will not be sent up the layers
|
[$node
set netif_(<interface number>)] set RXThresh_ <value> |
4.3.8 Modulation Scheme Settings
Modulation Scheme of an interface may be changed as follows:
|
[$node
set netif_(<interface number>)] set modulationscheme_<value> |
The value may be 1 for BPSK and 0 for no modulation. No other modulation scheme
is supported as of now.
4.3.9 Frequency settings and Loss factor
The frequency of operation and Loss factor may be setup as follows:
|
[$node
set netif_(<interface number>)] set freq_
<value> ; #frequency settings |
4.4
Adding Static Routes
Static routes may be added by lines in the following format:
|
[$node
set ragent_] addstaticroute <number of hops> <next hop>
<destination node> <interface> |
4.5 Setting up parameters for MAC
MAC Parameters for 802.11 may be setup using following lines of code:
|
Mac/802_11
set dataRate_
11mb
;# Setting the data rate |
Similarly, the following parameters may be configured for 802.11 by
using the command:
|
Mac/802_11
<parameter name> <value> |
Each of the parameters is self explanatory by its name:
|
MAC_ShortRetryLimit |
4.6 Adding ARP entries
One could add ARP entries as follows:
|
$ll
add-arp-entry <node-address> <mac-address> |
4.7 Using the 2p
Implementation
For 2p implementation while configuring netwrok components, set Link Layer to
2P link Layer and MAC to 2p Link Layer
|
set
val(mac)
Mac/WP2P_MAC ; |
After making link layer and mac layer configuration with each node, one
may attach either a tcp or ftp agent and send packets
4.7.1 Link Layer Configurations
The following settings may be made for a point to point link:
|
$ll
set-my-node-id
<id>
;set the node's id |
4.7.2 MAC Layer configurations
|
$mac
link-up
; activate the link/interface |
two-node.tcl: A sample
script for two nodes interacting over a type 1 antenna. A good starting point
to understand TENS
sample.tcl: A four node network with
multiple interfaces and static routing.
topo.tcl :
A more dense topology simulation.
2-p.tcl:
A script using the 2-p protocol
sample_long.tcl This script shows how
directional antennas can be used for simulating long distance links. It is same
as four node network except that the last hop is 6 Kms
6 Credits
TENS was output of the thesis of Siddharth Saha in.. during his maters
at Indian institute of Technology, Kanpur. It was then extended by Sabyasachi
Roy and Ashwinias a part of their Bachelor's project at IIT Kanpur. Dr
Bhaskaran Raman of Computer science and Engineering Department and Dr Kameswari
Chebrolu of electrical Engineering Department have been involved in upgrade of
TENS since 1.0 with a lot of bug fixes and feature addition, the most
significant being the 2-p implementation.
