Cognitive Radio

Cognitive Radio Network simulation is available from v7 of NetSim. Cognitive Radio Networks allows you to connect, if required, with Ethernet, Wireless LAN, IP Routing, TCP / UDP and allows users to log packet and event (in NetSim standard version only) traces.

New Experiment

In the Simulation menu select New Cognitive Radio Networks.

Create Scenario

Adding Devices –

  • Cognitive Radio Networks comes with the palette of various devices like Cognitive Radio CPE, Cognitive Radio Base Station, Switch, Router, Wired Node, Wireless Node, Access point, Incumbent etc.
  • Select the desired devices in the toolbar and click and drop on the environment.
  • To remove devices, right click on the particular device and then click Remove.

Connect the devices

Select the appropriate link in the toolbar and connect the devices by clicking on the device 1 and device 2.

  • Right click on the appropriate node or link and select Properties. Then modify the parameters according to the requirements. Routing Protocol in Application Layer of router and all user editable properties in DataLink Layer and Physical Layer of Access Point and Wireless Node are Global i.e. changing properties in one node will automatically reflect in the others in that network.
  • Select the Application Button on the ribbon and click on the empty region between the Grid Environment and the ribbon. Now right click on Application and select Properties. Multiple applications can be generated by using add button in Application properties.
  • Set the values according to requirement and click Accept.

Enable Packet Trace, Event Trace & Dynamic Metrics (Optional)

Click Packet Trace / Event Trace icon in the tool bar. To get detailed help, please refer section 6.5, 6.6 and 6.3 respectively. Select Dynamic Metrics icon for enabling Dynamic Metrics and click OK.

Run Simulation

Click on Run Simulation icon on the top toolbar. Set the Simulation Time and click on Simulate.

Sample Experiment

A sample network is created in “Configuration.xml” file which is located inside<NetSim installed Path>\Docs\ Sample_Configuration\ CognitiveRadio, which the user can open using NetSim and understand how devices are connected among themselves for that network and their default properties.

Furthermore, users can open this Configuration.xml file using Visual Studio 2010 and analyze how to write a designed network scenario manually. Further information is provided in “Understanding Configuration.xml file” under “Running NetSim via CLI” chapter.

Notes on Cognitive Radio implementation in NetSim:

  • CR BS allocates max one symbol per CPE. If the generation rate is more than the data filled in one symbol then allocation fails and it results in zero throughput.
  • The first symbol is reserved for CR control frames or any broadcast PDU
  • Operational frequency: It is the frequency band at which the incumbent operates. It ranges from 54 MHz to 862 MHz.
  • Operational interval(s): It is the time gap between two successive incumbent operations. It ranges from 0-10.
  • Operational time(s): It is the active period of the incumbent. i.e. If the operational interval is set to 5s, then incumbent operates with an interval of every 5s. If the operational interval is set to 0s, then the incumbent remains active.

For Operational Time(s) = 4, Operational interval=9

The timing diagram is as follows:

Incumbent --- 0s to 10s (OFF), 10s to 14s (ON), 14s to 24s (OFF), 24s to 28s (ON) ... and so on.

  • NetSim gives App layer throughput which is lesser than that of MAC layer throughput because of
  • TCP connection establishment
  • ARP set-up
  • Service flow creation CPE-BS and BS-CPE
  • BW request
  • To avoid the above effects
  • Generate custom traffic
  • Set DL/UL Ratio as 1:1 so that the BS transmits whatever it receives
  • Run UDP in transport layer
  • Use static ARP
  • Run Simulation for more than 100 sec

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