Design of Simulation


Design procedure followed to create this simulation is explained in this chapter. Improving the efficiency of the energy consumption across the wireless sensor networks is the main aim of this Energy Efficient Wireless Sensor MAC Protocol project and to evaluate the research two scenarios are created and the actual design followed to create these scenarios is explained in this chapter. First scenario deals with the normal MAC configurations, where few nodes are added to handle these and the second scenario deals with the Sensor MAC configuration, where the energy efficiency is improved and these two scenario are compared at the results level to understand the importance of S-MAC and the procedure followed to create this S-MAC protocol is given as below

Simulation tool: OPNET modeler and its importance 

As mentioned in the previous section there are two scenarios used across this simulation process and to derive the corresponding scenarios OPNET modeler is used as the simulation tool. OPNET modeler has many advantages when compared to the other simulation tools like NS2 and OMINET in terms of level of models supported and also the user interface provided to create a wide range of networks. NS2 is also much popular as OPNET modeler, but the only disadvantage with NS2 is that, it is complex in nature and involves lot of coding, where these aspects completely eliminated in OPNET modeler. OPNET also provides many model families against the wireless communication and the main importance of this tool lies with the aspect like a simple drag and drop operations can improve the simulation procedure and the object palette available with OPNET provides many objects to be configured. All the required objects can be dragged from this palette and they are configured as per the scenario requirements to create the actual network setup.  The simulation model involves, creating the required network, verifying the model consistency, running the simulation and finally evaluating the results. These steps are followed in creating any type of network and thus OPNET can be considered as the simple solution to create both the wired and wireless networks. Apart from these models, OPNET also provides the latest technologies like MANETs, wireless mesh networks and Zigbee networks also and thus all these models can be created and the performance of the networks can be evaluated easily. 

Design of first scenario 

Two scenarios are created in this simulation process as discussed in the previous section and the actual design principles followed to create the first scenarios are explained in this section. As the main aim of this project is to improve the energy efficiency using the S-MAC protocol, a simple mobile ad hoc network is created in this context to evaluate the wireless sensor networks. The first scenario deals with a normal networking conditions with the ordinary MAC protocol configurations are used in this scenario without changing any settings of the wireless LAN MAC protocol. In this scenario design 15 mobile nodes are used and they are considered as the wireless sensor nodes and a single wireless LAN server is also used and this server acts as the sink node, as there is no separate model in OPNET modeler to create the wireless sensor networks. Detailed network setup aspects followed to design this scenario are given as below 

The complete design of the scenarios can be categorized in to different aspects and they are discussed in detailed bellow. 

Basic network setup 

To evaluate the performance of any network, the basic network should be used and this section explains the basic network setup followed to create the first scenario. As discussed MANET is used the required model family a simple MANET model is created using the OPNET modeler. A network scale of 1000 X 1000 square meters is considered in this context and a simple campus is used to create the MANET and also all the mobile nodes considered operate across this campus and then MANET is chosen as the required model family in creating the simulation model.  Once the blank scenario is created and the required campus network is created with MANET is the model family 15 mobile nodes are created using the object palette.  Simple wireless LAN mobile nodes are considered as the required wireless sensor nodes and they move in the random direction during the routing process. Always a sink node is required to control the mobile sensor nodes and in this context a wireless LAN server fixed is used and this is also dragged from the object palette. This forms the basic network and to support and generate the traffic across the wireless sensor network always an application should be created and in this context, an application configuration node is also used to create the required application. The actual configuration settings done at this scenario are explained in the next section. Always OPNET requires a profile definition to support all the applications created and to achieve this a profile configuration node is create and to support the mobile configuration a mobile configuration node is also create and all these nodes are available at the MANET object palette as discussed. To summarize this section, following are the actual nodes used and they are listed as below

  • One wireless LAN server fixed node is used and this behaves like the sink node and controls the senor nodes
  • 15 wireless LAN mobile nodes are used and they act as the required sensor nodes
  • Required applications are created using the application configuration node
  • Profile definitions are created using the profile configuration node
  • Mobility to all the sensor nodes is given by the mobile configuration node

The actual configuration details done to these nodes are given in the coming sections.

Node level configuration 

As discussed in the above section, 15 mobile nodes are used in this network setup and all these nodes are wireless LAN mobile nodes and they are created by a simple drag operation from the object palette. When these nodes are created some configuration settings need to be done and they are discussed in this section. To create the required routing process across the network always a routing protocol is required and in general the MANETs supports wide range of routing protocols and among them AODV, OLSR, DSR and TORA are supported by OPNET modeler. In the simulation of this particular scenario, AODV is used as the routing protocol and all the mobile nodes are set to support this routing protocol. AODV is proved to be the best among many routing protocols in terms of energy efficiency and thus it chosen in this simulation process and all the nodes across the network are set to support this routing protocol. The application created across the application configuration level is also set to be supported across these mobile nodes across the application definitions section and also the profile created across the profile configuration is also defined at the profile definition section of the mobile nodes. The actual process followed in this context is explained in the next chapter. As the main aim of this project is to understand the energy efficient protocol implementation, the MAC protocol available at the wireless LAN configuration settings are checked once and they are not modified in this scenario and where they are modified in the next scenario and discussed later.  Once all the mobile nodes are set against the configuration now the server or the sink node is edited to support the required application and profile settings. Even in this case AODV is used as the routing protocol and the wireless LAN MAC attributes are set to default in this scenario and they are modified in the next scenario to improve the energy efficiency. 

Application definitions 

To generate the required traffic across the network, always the mobile nodes and the corresponding server should support any of the application and this application is created at the application configuration node. Application config node is edited in this context to define the required number of application and in this scenario only one application is used to create the traffic and it is File transfer application and in general FTP generates the TCP traffic and this traffic is used to create the communication patterns across the network.  Detailed description of the FTP application is set at this stage in terms of the load on the network and the number of packets to be generated and once this application created it should be supported against a profile in the network and the actual design process for this process is given in the next section. 

Profile definitions 

In general across OPNET every application created to generate the traffic across the network should be supported by a profile definition and this is created using the profile configuration node as discussed before. Every application has a separate profile and as a single application is created in this process a single profile is create to support the application. FTP profile is created in this scenario and this profile supports the FTP application and apart from the application support few aspects like the profile start time and end time are also defined in this level. For this scenario the profile start time is set to a constant value of 100 seconds and the repeatability of the profile is set till the end of the profile. Once the required profile is set now the required mobility to the nodes should be added and this is explained in the later section as below 

Mobile definitions

As the nodes used in this simulation are mobile in nature the required mobility should be added to all the nodes. As 15 mobile nodes are added in this network, all these nodes should support any of the mobility models and this model is defined using the mobile configuration node as discussed in the previous section. Mobile configuration node is added from the object palette and edited to create the required mobility model and in this scenario a default random waypoint model is used and this can be chosen at the mobile configuration node level. Apart from the mobility model few aspects like speed of the mobile nodes and pause time are also defined and in this simulation process they are set to 10 meters per sec and 0 seconds respectively. These values indicate that all the mobile nodes move with a speed of 10 meters per second across the network and there is no pause time incurred in this process. Once the mobility is defined, this should be applied to all the mobile nodes and this can be done by using the topology menu and setting the default random waypoint mobility and the actual process followed in this context is explained in the next chapter. 

Setting the performance metrics

All the required configuration steps done across the node level, application config level, profile config and mobile config are explained in the previous sections and once these steps are done the actual performance metrics should be set and the design process is explained in this section. As the aim of this project to improve the energy efficiency at the wireless LAN MAC parameters the corresponding parameters used and also the FTP application parameters are also used in this context. Following are the actual parameters used to analyze the performance of the wireless LAN and FTP and they are listed below

Following are the FTP metrics used to analyze the performance of the overall network

  • Download response time
  • Traffic received in packets per sec
  • Traffic sent in packets per sec
  • Upload response time

Following are the wireless LAN metrics used to analyze the performance of the overall network 

  • Data dropped
  • Delay in seconds
  • Load in bits per second
  • Medium access delay in seconds
  • Throughput in bits per sec 

Once the required performance metrics are set across the simulation process it is run against the simulation time and the corresponding results are analyzed for this scenario and the design of the next scenario is given in the next section  

Design of second scenario 

Design of the second scenario is almost similar to the first scenario and this can be created by a simple duplicate scenario option available across the OPNET modeler.  Wireless LAN MAC parameters are edited in this context to create the second scenario and the actual parameters changed across this scenario are as listed below 

  • Transmit power is set to 0.020
  • Packet reception power threshold is set to -95
  • RTS threshold is set to 256
  • Fragmentation threshold is set to 256
  • CTS to self option is set to enabled
  • Short retry limit is set to 7
  • Long retry limit is set to 4
  • AP Becon interval is set to 0.02 seconds
  • Max receive life time is set to 0.5
  • Buffer size is set to 256000
  • Roaming capability is set to disabled
  • Large packet processing is set to dropped 

Thus the complete design aspects followed to create both the scenarios are explained in this chapter and the actual simulation process followed to achieve this design is given in the next chapter.