Why use a Network Simulator for research ? Introduction to NetSim Cognitive Radio Basics Designing Cognitive Radio networks using NetSim Modifying Cognitive Radio source C code in NetSim How to develop custom metrics? Q & A

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NetSim v9Model - Predict - Validate
Network Simulation/Emulation Platform
TM

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Webinar Contents
1. Why use a Network Simulator for research ?
2. Introduction to NetSim
3. Cognitive Radio Basics
4. Designing Cognitive Radio networks using NetSim
5. Modifying Cognitive Radio source C code in NetSim
6. How to develop custom metrics?
7. Q & A

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1. Why use a Network
Simulator for research ?

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Communication Networks
have become too complex for
traditional analytical methods
or “rules of thumb” to provide
an accurate understanding of
system behavior and possible
problems and solutions

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I. Networking traffic will
quadruple by 2017 driven
by wireless & mobile
communication
II. 2+ billion videos watched
online every day
III. Mobiles, tablets & sensors
to join with existing internet
cloud to form “network of
things”
I. Mobile Ad-hoc
Networks
II. Wireless Sensor
Networks
III. Cognitive Radio
IV. LTE / LTE-A
V. Internet of Things (IOT)
50 % of all research papers in IEEE & ACM refer a
Network Simulator
Observations in computer
networking domain
Key areas of research &
development

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2. Introduction to
NetSim

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NetSim is a popular tool for Network Design, Network R & D and
defence applications. It allows users to create network
scenarios, model traffic and study network performance metrics
Wide range of technologies across LAN, WAN, Wireless,
Cellular, Cognitive Radio, Sensor Networks, IOT and LTE as per
international Standards
Open architecture with protocol C source code for users to
write, link and de-bug.

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NetSim - Customer Segments
• Enterprise
– Network design
– Network validation
• Defence
– Network Centric Warfare
• R&D Labs
– Protocol Development
– New Technology testing
• Academic
– Network Labs (B.Tech/BS),
– Advanced Network Labs(M.Tech/MS) – ECE,CSE,IT
– Phd thesis/M.Tech Projects

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Architecture
Network Stack in NetSim Example of Internetwork Protocols
Kernel

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Standards Implemented
Component
No
Networks / Protocols
International
Standards
Component 1
(Base. Required for
all components)
Internetworks: Ethernet - Fast & Gigabit, Address
Resolution Protocol, WLAN - 802.11 a, b, g , n, ac and e,
Propagation - Free space, Log-normal Shadowing, Rayleigh
Fading, IPv4 with VPN, Firewalls, Routing - RIP, OSPF,
Queuing - Round Robin, FIFO, Priority, TCP, UDP.
Common Modules Applications: Traffic Generator: Voice,
Video, FTP, Database, HTTP, Email, Peer-to-peer and
Custom. Virtual Network Stack, Simulation Kernel
Command Line Interface, Metrics Engine with packet and
event trace, Packet Animator
IEEE 802.3, RFC 826
802.11 a/b/g/n/ac/e,
RFC 2453,2328, RFC's
793, 2001 and 768
Component 2
Legacy Networks: Aloha - Pure & Slotted, CSMA/CD,
Token Ring, Token Bus, ATM, X.25, Frame Relay,
Multi-Protocol Label Switching (MPLS)
IEEE 802.3, IEEE
802.4, IEEE 802.5,
ATM Forum, ITU
Forum, IETF RFC 3031
Component 3 BGP Networks: Border Gateway Protocol (BGP)
IETF, RFC’s 1771 &
3121
Component 4
Advanced Wireless Networks: MANET - DSR, AODV,
OLSR, ZRP, Wi-Max
IETF, RFC 4728, 3561,
3626, IEEE 802.16d
Component 5 Cellular Networks - GSM, CDMA
3GPP, ETSI, IMT-MC,
IS-95 A/B, IxRTT, 1x-
EV-Do, 3xRTT

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Standards Implemented
Component
No
Networks / Protocols
International
Standards
Component 6
(Component 4
required)
Wireless Sensor Networks, IOT & Personal Area Networks:
WSN with agent model & battery models ZigBee
IEEE 802.15.4 MAC,
MANET in L3
Component 7
Cognitive Radio Networks
WRAN
IEEE 802.22
Component 8 Long Term Evolution
LTE
3GPP
Component 9
(Component 4
required)
Military Radio
TDMA Link 16
--

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What’s new in NetSim v9
1. New Technologies
– Internet of things
– 802.11 ac (Gigabit Wi-fi)
– Rate adaptation algorithm for
WLAN
– Military Radios: HF, UHF and
VHF Bands
2. Network Emulator Add-on Module
– Connect NetSim to Real Devices
running Live Application
3. Interfacing with softwares
– MATLAB interface
– Wireshark Interface
4. Accelerated and multithreaded
kernel
– Approx. 40x times faster than
v8.3 for large simulations
5. Simulation Scale up
– Pro version tested up to
100,000 devices

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3. Cognitive Radio
Basics

14. IEEE 802.22 WRAN
Cognitive Radio Networks(CRN)

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17. Spectrum Crunch
 Spectrum crunch refers to the potential lack of sufficient
wireless frequency spectrum needed to support a growing
number of consumer devices, along with various
government and private sector uses of radio frequencies
within a broad spectrum allocated for different types of
wireless communications.
But…..

18. The goal for the Spectrum
Occupancy Measurements
at Chicago was to gain a
better understanding of the
actual utilization of
spectrum in this dense
urban environment with the
potential to identify
spectrum bands with low
occupancy

19. Source : Spectrum Occupancy Measurements Chicago, Illinois November 16-18, 2005

20.  Spectrum measurements indicate that there are:
– Heavy spectrum utilization in unlicensed bands
(e.g., ISM band)
– Low (e.g., TV bands) or medium (e.g., some
cellular bands) spectrum utilization in licensed
band
 Cognitive radio (CR) technology is a promising
technology for efficient utilization of the available
spectrum.

21. What is Cognitive Radio
• Cognitive radio is a wireless communication system which
is aware of the environment and its changes and can adapt
its transmission parameters accordingly.
Cognitive Capability: The ability to sense the unused
spectrum at a specific time and location.
Reconfigurability: The ability to receive and transmit at
different frequency band enables the cognitive radio to
reconfigure its parameters and select the best band.
– This operates in 54 MHz to 862 MHz band.

23. Components
• Primary network
◦ Primary users:
 Primary users have the license to operate in certain spectrum bands
◦ Primary base station:
 Controls the access of primary users to spectrum
• Secondary network
◦ Secondary users:
 Secondary users have no licensed bands assigned to them.
◦ Secondary base-station:
 A fixed infrastructure component with cognitive radio capabilities and
provides single hop connection to secondary users.

24. Cognitive Radio Cycle

25. 4. Designing Cognitive
Radio networks using
NetSim

26. 3. Cognitive Radio
Basics (Contd)

27. Super Frame Structure
Each frame consists of:
• Superframe preamble: is used for time synchronization
• Frame preamble: is used for channel estimation
• Superframe Control Header (SCH): carries BS MAC address
along with the schedule of quiet periods for sensing, as well as other
information about the cell

28. Super Frame Structure
At the beginning of every superframe, the BS shall transmit the
superframe preamble and the SCH on the operating channel.
In order to associate with a base station, a CPE must receive the
SCH to establish communication with the BS. During each MAC
frame, the BS shall manage the upstream and downstream
operations, which may include ordinary data communication,
measurement activities, coexistence procedures, and so on.

29. Frame Structure
A frame is comprised of two parts: a downstream (DS) subframe and
an upstream (US) subframe. The boundary between the DS and US subframes
shall be adaptive to adjust to the downstream and upstream relative capacity.
The upstream subframe may contain scheduled upstream PHY PDUs, each
transmitted from different CPEs for their upstream traffic.
The FCH specifies the burst profile and the length of either the DS-MAP, if
transmitted, or the US-MAP. If neither, the DS-MAP nor the US-MAP is
transmitted, the value shall be set to zero.

31. 4. Designing Cognitive
Radio networks using
NetSim (Contd)

32. Typical Cognitive Radio Applications

33. References
 Cognitive Wireless RAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications: Policies and Procedures for Operation in the TV Bands by IEEE Computer
Society
 Spectrum Occupancy Measurements Chicago, Illinois November 16-18, 2005 by Mark A.
McHenry, Dan McCloskey, Dennis Roberson, John T. MacDonald
 Detection the Spectrum Holes in the Primary Bandwidth of the Cognitive Radio Systems
in Presence Noise and Attenuation by Ahmed S. Kadhim, Haider M. AlSabbagh
 Cognitive radio - The IEEE 802.22 standard by Dr.-Ing. Mohamed Kalil

34. 5. Modifying Cognitive
Radio source C code in
NetSim

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Writing Custom Code
• Source C codes for all protocols are provided along with
• Users can modify code and link custom code to NetSim
• Integrated debugging, animation and tracing available for custom code

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Custom code - Hands on
• To access Protocol Source Code
– NetSim Installation Directory
(C:Program Files (x86)NetSim Standard)  “src” folder  “Simulation” folder
NOTE- Please make a copy of the “Simulation” folder before making any
modification
Editing Protocol for “Hello World” Program

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Reduce your learning curve - APIs
• NetSim provides a wide variety of API’s for protocol developers. These
are available as:
• packet.h - Packet related API’s
E.g. Create_Packet( ), Copy_Packet( ), Free_Packet( ) etc
• stack.h - Network/device/link and event related API’s
E.g. Get_Device_IP( ), Get_Connected_Link( ), Add_Event( ) etc
• list.h - Optimized list operation calls since NetSim uses lists extensively
E.g. Add_to_list( ), Sort_list( ) etc
• NetSim_Graph.h – This is used for plotting graphs using GNU plot
• IP_Addressing.h – For setting & getting IP address per the appropriate format
E.g. Convert_IP_to_string( ), Compare_IP( ) etc
. . . and many more

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6. How to develop
custom metrics?

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• In NetSim, users can add their own customized metrics
in the Performance metrics window.
• Users need to edit the Backend C source code in order
to get the metrics.
• An example regarding Cognitive radio is provided.
– In this example, users will print the number of Superframes
and the time at which they start, in the performance
metrics

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Modification in 802_22.h
int SuperframeCount;
int Superframe_Num[500];
double Superframe_time[500];
Copy the above code at Line 1224 in 802_22.h file

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Modification in 802.22c
case TRANSMIT_SCH:
SuperframeCount+=1;
Superframe_Num[SuperframeCount-1]=SuperframeCount;
Superframe_time[SuperframeCount-1]=pstruEventDetails-
>dEventTime;
fn_NetSim_CR_TransmitSCH();
break;
Copy the above code(in red colour) at Line 89-91 in 802_22.c file(inside
TRANSMIT_SCH case of fn_NetSim_CR_Run() function)
SuperframeCount=0;
Copy the above line at Line 12 in 802_22.c file
(inside int fn_NetSim_CR_Init() function)

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Modification in 802.22c (contd..)
_declspec(dllexport) int fn_NetSim_CR_Metrics(char* file)
{
FILE *fp;
int i;
fp=fopen(file,"a+");
fprintf(fp,"#CR Superframe Metricsn");
fprintf(fp,"Superframe IDtTimen");
for(i=0;i<=SuperframeCount;i++)
fprintf(fp,"%dt%fn",Superframe_Num[i],Superframe_time[i]);
return fn_NetSim_CR_Metrics_F(file);
}
Copy the above code(in red colour) at Line 147 in 802_22.c file(inside
fn_NetSim_CR_Metrics function)

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• Please follow the same procedure as with custom code editing
• Create Dll file and copy to NetSim bin folder
• Create a Cognitive Radio scenario with default properties
• Simulate for time = 2 secs (for faster simulation)

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Education - International
Defence / Space / Industry
Over 300+ Customers across 15 countries
Education - India

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Research Areas
Wireless Sensor Networks
(WSN)
• Energy efficiency and power
management
• Efficient protocol design and
operation
• Self configuration and fault tolerance
• Routing
• Localization
• LEACH
Cognitive Radio Networks
(WRAN)
• Spectrum sensing and incumbent
detection
• Spectrum allocation
• Geolocation and location based services
• Interference analysis, measurement and
modeling of spectrum usage
• Protocol architecture
Mobile Ad-hoc Networks
(MANET)
• Routing protocols - Location based,
Power aware etc
• QoS in adhoc networks
• Intrusion detection
• Performance Analysis
• Vehicular adhoc networks
Internet Of Things
(IOT)
• Seamless integration of heterogeneous
devices
• Network architecture for IOT
• Energy management and sustainable
operation of IOT
• 6LoWPAN based IOT design
• Modeling and simulation of large scale
IOT networks

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7. Q & A Session
Note: Depending on the available time, we will try to cover all your questions. In
case your query is not answered, we assure you to answer your question via email.

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