Article Directory
1. Project Editor
The commonly used functions of the toolbar under the OPNET software network model editing interface are as follows.
The button marked 1 is to open the object panel, as shown in the figure below, you can select any object you want.
The button marked 2 is to run the discrete event simulation. After clicking, the window shown in the figure below will pop up. You can set parameters such as simulation time and start the simulation.
The button marked 3 is to view the results. After clicking it, as shown in the figure below, you can view the results of the global quantity, or you can view the results of a certain object.
Object-related operations are generally found under Topology in the menu bar.
Topology——>Open Annotation Palette can add annotations, including graphic boxes, lines or text.
Scene-related operations are generally found under Scenarios in the menu bar. Commonly used operations include creating a new scene, copying a scene, and managing a scene, as shown in the figure below.
Ctrl + number keys at the top of the keyboard can switch scenes. The switching of 10 or more scenarios needs to be realized through the menu Scenarios-->Switch to Scenario.
2. Node model editor
The node model editor is used to define the behavior of each node. A node is usually composed of multiple modules, and its behavior is determined by the different modules it uses. Each module completes a part of node behavior, such as data generation and storage.
The OPNET node model editor provides the resources needed to simulate internal functions. In the node model editor, users can use a variety of modules, each of which implements a certain aspect of node behavior, such as data generation, data storage, and data storage. Processing or routing and data transmission, etc. A single node model usually consists of multiple modules, sometimes dozens or even hundreds of modules. Packet streams (packet streams) and statistical wires (statistical wires) can connect different modules. Packet streams carry data packets between modules. Transmission, statistic wires can monitor the changes of specific parameters of the module, through the combined use of modules, packet streams and statistic wires, users can simulate the behavior of the node.
Modules, packet flows, and statistical lines in the node model are labeled in the figure below.
Several main functions of the toolbar under the node model editing interface are shown in the figure below.
From left to right: Add Processor, Add Queue, Add Packet Line, Add Status Line, Add Logic Line, Add Point-to-Point Receiver, Add Point-to-Point Transmitter, Add Bus Receiver, Add Bus Transmitter , Add wireless receiver, add wireless transmitter, add antenna.
Under Interfaces in the menu bar, you can set model properties, node interfaces, node statistics, etc.
New node models can be created, as shown in the image below.
After completion, add the attribute name under Interfaces->Model Attributes.
Modify the relevant properties under Interfaces——>Node Interfaces, and change the Supported of mobile and satellite to no, otherwise there will be several node models later.
Under Interfaces——>Node Statistics, set as shown below.
Prom. Group will be renamed.
File——>save and save it as a file named demo, then open the object panel under the scene and search for demo, as shown in the figure below.
We can add it as an object to our project.
3. Process model editor
The process model editor is used to generate a processor model, which is used to realize the module function in the node model editor. The processor model is described by a finite state machine, and the state is represented by an icon, and the transition between states is represented by a line. Each state Included processing is described using embedded C/C++ code segments, as shown in the figure below.
Among them, the green state machine is a mandatory state machine, and the red one is a non-mandatory state machine. Double-click the upper part of the state machine to write the entry execution code of the state machine, and double-click the lower part of the state machine to write the exit execution code of the state machine.
Several main functions of the toolbar under the process model editing interface are shown in the figure below.
From left to right: create state, create transition, set initial state, state variable area (State Variables), temporary variable area (Temporary Variables), head block (Head Block), function area (Function Block), diagnosis area ( Diagnostic Block), termination area (Termination Block) and compilation process.
4. Link Model Editor
Select Link Model from the File -> New drop-down menu to create a new link model editor, and its interface is shown in the figure below.
The link model editor is used to generate new link types. Each new link type can have different characteristics. Each link object is described in the link model. For different link objects, each type Links contain specific attribute interfaces, annotations and representation methods. The link created in the project editor is a specific instance of the link model, so when the properties of the link model are modified, the link instance will automatically inherit the modified properties.
The following items can be edited in link model editing:
(1) Supported link types
Each link model can support one or more of the four basic link types, namely ptsimp (point-to-point duplex link), ptdup ( Point-to-point simplex link), bus (bus link) and bus tap (bus tap link). The design of the wireless link is not included in the link editor. It is a function related to the relative position of the node, transmission and many factors in the operating environment generated by the dynamic definition of the simulation kernel.
(2) Keywords
The keywords of the link model allow to selectively display the link model in the project editor object template. When configuring an object template, OPNET compares the key to the requested key to decide whether to select this model. This mechanism reduces the number of models in the object template and only displays those models that are relevant to the current application.
(3) Comments
contains a series of annotations in the link model, which describe the characteristics of the link, potential applications and any information that users may be involved in. Because some users do not have access to the link model internals, annotations become the main information available to such users. OPNET facilitates user access to information by embedding relevant documentation of the model interface as an inherent part of the model itself.
(4) Attribute
The node and process models can respectively affect the attribute expression and use of nodes and modules. Similarly, the link model provides a specification for the attributes of link objects in the project editor. The relationship between link models and links is similar to the relationship between process models and modules. The link model can specify configuration information for the embedded properties of the link object through property pre-allocation, property hiding, property renaming and changing property priority.
5. Package format editor
The packet format editor is used to define the internal structure of the data packet, and the packet format consists of one or more fields. The package format is a structure composed of fields, and the package format specifies the name, data type, default value, size and related comments of each field. In the call of the core program, a specific type of data packet can be introduced through the menu "File → Declare Packet Formats" in the process model editor. In a graphical environment, fields are represented as a series of colored rectangles whose size is proportional to the number of bits specified in the FieldSize property.
The interface of the package format editor is shown in the figure below.
6. Antenna Model Editor
The received power of a signal is usually calculated as a function of many factors, including the directional vector between the antennas and the gain of each antenna along this directional vector. The antenna gain model specified in the antenna model editor can be used to provide gain values given the relative positions of the nodes. The Antenna Editor is used to model the gain characteristics of the antenna in all directions. If the relative position of each node is known, OPNET can use the gain characteristic of the antenna to determine the gain value.
The antenna model describes the antenna gain value in different directions, and the antenna gain describes the phenomenon that the transmitted signal energy is amplified or attenuated . The shaping of the transmitted power is based on the physical characteristics of the antenna structure and the azimuth of the transmission.
In the antenna model editor, users can create, edit and view antenna models. Antenna models are two-dimensional functions of three-dimensional antenna gain established in dB.
The interface of the antenna model editor is shown in the figure below.
The five buttons in the toolbar are from left to right: smoothing, normalization, setting the number of Phi layers, setting the lower limit of the ordinate and setting the upper limit of the ordinate.
The smoothing operation is to smooth the sharp edges and burrs of the graph, and the realization of the smoothing algorithm is realized through a window sliding along the X axis.
The normalization operation scales down or up the entire model appropriately such that the total gain over the entire spherical model is zero.
The Set Phi Stratifications operation sets the sampling number for line graphs or 3D graphs. The number of samples determines how many sample elements or discrete elements are used when approximately constructing the continuous function.
The operation of setting the lower limit of the ordinate sets the lower limit for the Y axis of the antenna model graph, and the operation of setting the upper limit of the ordinate sets the upper limit for the Y axis of the antenna model graph.
7. Modulation Curve Editor
The standard modulation curves provided by OPNET include: BPSK, DPSK, FSK, PSK, QPSK, etc.
The modulation curve editor is used to generate modulation functions to characterize the sensitivity of coding and modulation methods to noise. The modulation function plots the bit error rate as a function of the signal-to-noise ratio. The modulation curve reflects the relationship between the bit error rate and the signal-to-noise ratio in the wireless transmission process. But the graphical definition is not accurate enough, so in OPNET Modeler, the modulation curve can be created by EMA code. In the wireless module, the modulation curve is used to describe the information coding and modulation mechanism, and the bit error rate is used as a function of the signal-to-noise ratio.
The interface of the modulation curve editor is shown in the figure below.
The toolbar is smoothing, setting the number of discrete sampling points used in the function, displaying the lower limit of the X-axis in the image, displaying the upper limit of the X-axis in the image, displaying the lower limit of the Y-axis in the image, and displaying the upper limit of the Y-axis in the image.
8. Icon library editor
Use the icon library editor to edit your own icons and use them as logos for network objects. You can define your own icon by clicking the right mouse button in the blank space of the operation space or selecting the menu Edit→New Icon.
The interface of the icon library editor is shown in the figure below. Double-click the placed icon to pop up the Image Editor window.
You can import or export icons through the menu File→Import or File→Export, but please note that you can only import pictures in the format supported by the picture editor (such as TIFF, BMP format), otherwise it will not be displayed (GIF or JPG format).
Nine, simulation sequence editor
The Simulation Sequence Editor can define more comprehensive simulations.
The interface of the simulation sequence editor is shown in the figure below.
Summarize
The above is all the content introduced by the OPNET Modeler software editor. There are still many functions of each editor. At this stage, it is just a preliminary understanding. Later, when it is actually used, it will be more in-depth study. I hope this article will help you learn OPNET Modeler software can help!
Bibliography of this article: OPNET Network Simulation/Edited by Chen Min. - Beijing: Tsinghua University Press, 2004