Network Model Libraries

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When creating an accurate network digital twin of the physical network, several components are required, including network model libraries. Similar to how a blend of hardware and software helps construct live networks, a variety of network protocols, equipment, radio waveforms, and other elements combine to create network digital twins. SCALABLE’s EXata and QualNet platforms, along with the Network Defense Trainer, include a GUI-driven virtual network model building facility and libraries to meet your needs.

Network model libraries include communications systems model libraries, which feature various definitions of network protocols and communications equipment waveforms. You can use both default and custom libraries based on your specific needs, depending on the architecture of your networks and functionality requirements. Users can implement different hardware and software components to interface with the waveforms and network protocols, enabling users to test wireless communications. Users also have the option of using Design Mode to develop customized communication system models. You can then incorporate those models into specialized virtual network models.

Users can also freely create custom models and make adjustments to existing models. They can then add these models to communications systems and integrate them into virtual network model configurations. Clients have access to source code for component models from SCALABLE, and C/C++ is used to develop communication system models. With a few clicks, you can add a range of situations and details to your model. Whether it’s the terrain, antennae weighting, IoT, MANET, or signal-to-noise interference, we are either likely to have an existing model or can work with you to create one for your specific environment.

To help meet the needs of continually evolving network and system technologies, our latest network library also includes models for Bluetooth and 5G networks.

Bluetooth Applications

The new model library is compatible with Bluetooth applications that entail connecting multiple devices. The Bluetooth model library features Bluetooth as a radio type, which can be combined with other Bluetooth transmissions, Wi-Fi access points, and various net-enabled devices. Using this model, you can simulate generic multimedia traffic. The simulation can then provide accurate insight into interference and overall network performance, which you can view via clearly defined statistics.

5G Capabilities

In addition to Bluetooth, you can use the new model library to develop 5G network models. In one scenario, we used the new model library for an Enhanced Mobile Broadband (eMBB) model, in which case we connected the 5G core to two GMBs. Each GMB was connected to several UEs, one of which moved from one GMB to another. The model featured representations of the 5G core functions emulated using the EXata 7 platform. From there, the eMBB network spanned over PHY, MAC, and Network Core layers. Using 5G scenarios, you can also view stats to gauge the performance of the network and systems.

Network Model Library Classes

Depending on your needs, the network model library features several “classes” or component libraries that can perform different functions. Combined, each of these classes can help you develop nearly any scenario and simulation based on your specific networks, equipment, and systems. The classes include:

  • Cyber — focuses on cyber attacks against the network
  • Equipment — consists of the hardware components
  • Human-in-the-Loop (HITL) — specific human-directed commands that influence certain elements throughout a given scenario
  • Images — any icons or other visual elements that provide graphic representations of behaviors and elements
  • Integration Interfaces — certain protocols and mechanisms that allow SCALABLE systems to interact with other simulators or systems
  • Protocols — network waveforms and protocols that facilitate communications between equipment
  • Terrain — the type of physical terrain where communications occur, e.g. mountainous terrain or urban areas
  • Weather — weather behavior details and information about how this weather impacts communications

Standard and Optional Component Libraries

Apart from the various classes, there are several standard and optional component model libraries that users can access using the EXata and QualNet platforms. Both libraries include a variety of protocol, equipment, weather, and terrain models.

Standard libraries specifically include:

Developer Library

The Developer Library includes a very long list of standard communications protocols and mechanisms.

The library supports:

MAC Layer

  • 802.3 LAN/Ethernet
  • Abstract Link MAC
  • Abstract Satellite Model
  • Address Resolution Protocol (ARP)
  • Logical Link Control (LLC) Protocol

Network Layer

  • Domain Name System (DNS)
  • Dynamic Host Configuration Protocol (DHCP)
  • Fixed Communications Model
  • Internet Control Message Protocol (ICMP)
  • Internet Control Message Protocol version 6 (ICMPv6)
  • Internet Group Management Protocol (IGMP)
  • Internet Protocol – Dual IP
  • Internet Protocol version 4 (IPv4)
  • Internet Protocol version 6 (IPv6)
  • IPv6 Autoconfiguration Model
  • Neighbor Discovery Protocol

Unicast Routing

  • Bellman-Ford Routing Protocol
  • Routing Information Protocol next generation (RIPng)
  • Routing Information Protocol/Routing Information Protocol version 2 (RIP/RIPv2)
  • Static and Default Routes

Multicast Routing

  • Static Multicast Routes

Queues and Schedulers

  • First-In First-Out (FIFO) Queue
  • Random Early Detection (RED) Queue
  • Random Early Detection with In/Out (RIO) Queue
  • Round Robin Scheduler
  • Self-Clocked Fair Queueing (SCFQ) Scheduler
  • Strict Priority Scheduler
  • Weighted Fair Queuing (WFQ) Scheduler
  • Weighted RED (WRED) Queue
  • Weighted Round Robin (WRR) Scheduler

Transport Layer

  • Abstract Transmission Control Protocol (Abstract TCP)
  • Multicast Dissemination Protocol (MDP)
  • Transmission Control Protocol (TCP)
  • User Datagram Protocol (UDP)

Application Layer

  • Background Traffic Model
  • Constant Bit Rate (CBR) Traffic Generator
  • File Transfer Protocol (FTP)
  • File Transfer Protocol/Generic (FTP/Generic)
  • HyperText Transfer Protocol (HTTP)
  • Lookup Traffic Generator
  • Multicast Constant Bit Rate (MCBR) Traffic Generator
  • Super Application Traffic Generator
  • Telecommunications Network (TELNET)
  • Traffic Generator (Traffic-Gen)
  • Trace File-based Traffic Generator (Traffic-Trace)
  • Variable Bit Rate (VBR) Traffic Generator


  • Asynchronous Transfer Mode (ATM)

Vendor Interfaces

  • AGI System Toolkit (STK) Interface


  • Faults
  • File-based Node Placement Model
  • Grid Node Placement Model
  • Random Node Placement Model
  • Uniform Node Placement Model

Wireless Library

The standard Wireless Library includes many typical wireless protocols and mechanisms.

The library supports:


  • Airplane Pathloss Model (New)
  • Constant Shadowing Model
  • Fast Rayleigh Fading Model
  • Free-space Pathloss Model
  • Inter-channel Interference Model
  • Irregular Terrain Model (ITM)
  • Lognormal Shadowing Model
  • Millimeter Wave Pathloss Model (New)
  • Pathloss Matrix Model
  • Rayleigh Fading Model
  • Ricean Fading Model
  • Two-ray Pathloss Model

Physical (PHY) Layer

  • 802.11p PHY Model
  • 802.11a/g PHY Model
  • 802.11b PHY Model
  • 802.11n PHY Model
  • 802.11ac PHY Model
  • 802.11ax PHY Model
  • Abstract PHY Model
  • Antenna Models
  • Bit Error Rate-based (BER) Reception Model
  • Bluetooth PHY Model (New)
  • Radio Energy Models
  • SNR-based Reception Model

Media Access Control (MAC) Layer

  • 802.11 MAC Protocol
  • 802.11p MAC Protocol
  • 802.11e MAC Protocol
  • 802.11n MAC Protocol
  • 802.11ac MAC Model
  • 802.11ax MAC Protocol
  • 802.11s MAC Protocol
  • Aloha MAC Protocol
  • Abstract Network Equation – Satellite (ANESAT) Model
  • Bluetooth Classic MAC Protocol (New)
  • Bluetooth Low Energy MAC Protocol (New)
  • Carrier Sense Multiple Access (CSMA) MAC Protocol
  • Generic MAC Protocol
  • Microwave Links
  • Multiple Access Collision Avoidance (MACA) MAC Protocol
  • Time Division Multiple Access (TDMA) MAC Protocol

Unicast Routing

  • Ad-Hoc On Demand Distance Vector (AODV) Routing Protocol
  • Bordercast Resolution Protocol (BRP)
  • Dynamic MANET On-demand (DYMO) Routing Protocol
  • Dynamic Source Routing (DSR) Protocol
  • Fisheye State Routing Protocol
  • Intrazone Routing Protocol (IARP)
  • Interzone Routing Protocol (IERP)
  • Landmark Ad Hoc Routing (LANMAR) Protocol
  • Location-Aided Routing (LAR) Protocol
  • Optimized Link State Routing Protocol – INRIA (OLSR-INRIA)
  • Optimized Link State Routing Protocol version 2 (OLSRv2)
  • Source Tree Adaptive Routing (STAR) Protocol
  • Zone Routing Protocol (ZRP)

Application Layer

  • Bluetooth Advertiser Application Model (New)
  • Bluetooth Application Model (New)

Multicast Routing

  • On-Demand Multicast Routing Protocol (ODMRP)


  • File-based Mobility Model
  • Group Node Placement and Mobility Models
  • Random Waypoint Mobility Model


  • Cartesian Terrain Format
  • Digital Elevation Model (DEM) Terrain Format
  • Digital Terrain Elevation (DTED) Terrain Format
  • ESRI Shapefile Terrain Format
  • Urban Terrain Data Format


  • Battery Models
  • Weather Pattern Model

Multimedia & Enterprise Library

The Multimedia and Enterprise Library covers an array of protocol and equipment elements.

The library supports:

Media Access Control (MAC) Layer

  • Detailed Switch Model
  • Switched Ethernet
  • Virtual LAN (VLAN)

Network Protocols

  • Generic Routing Encapsulation (GRE) Model
  • Layer 3 Switch Mode
  • Mobile IPv4

Unicast Routing

  • Border Gateway Protocol version 4 (BGPv4)
  • Enhanced Interior Gateway Routing Protocol (EIGRP)
  • Interior Gateway Routing Protocol (IGRP)
  • Open Shortest Path First version 2 (OSPFv2) Routing Protocol
  • Open Shortest Path First version 3 (OSPFv3) Routing Protocol

Multicast Routing

  • Distance Vector Multicast Routing Protocol (DVMRP)
  • Multicast Extensions to OSPF (MOSPF)
  • Protocol Independent Multicast Protocol: Dense Mode (PIM-DM) and Sparse Mode (PIM-SM)
  • Multicast Source Discovery Protocol (MSDP)

Router Configuration

  • Hot Standby Router Protocol (HSRP)
  • Policy-based Routing Protocol (PBR)
  • Route Map
  • Route Redistribution
  • Router Access List
  • Router Model

Quality of Service (QoS)

  • Differentiated Services (DiffServ)
  • Multiprotocol Label Switching (MPLS)
  • Quality of Service Extensions to OSPF (QOSPF)

Multimedia Applications

  • H323 and H225 Protocols
  • Real-time Transfer Protocols
  • Session Initiation Protocol (SIP)
  • Voice over Internet Protocol (VoIP)

Network Management Library (EXata only)

The Network Management Library includes a model of the Simple Network Management Protocol (SNMP).

The SNMP is a UDP-based network protocol which runs over IP using Port 161 and 162. It is used mostly in network management systems to monitor network-attached devices for conditions that warrant administrative attention. SNMP makes management data available in the form of variables on the managed systems, which describe the system configuration. These variables can then be queried (and sometimes set) by managing applications.

The EXata platform offers the capability to manage nodes in a scenario by an SNMP manager. The SNMP managers can review the current network status, set the network properties, or assign traps to receive feedback from the managed nodes. EXata provides this feature by implementing SNMP agents on nodes in a scenario. SNMP agents can be enabled on all nodes and can be configured to handle the SNMP get and set commands. Additional configuration is required to handle the trap command.

Implemented features:

  • Command responder application
  • Notification originator
  • User-based Security Module (for SNMPv3)
  • Authentication (for SNMPv3)
  • Encryption (for SNMPv3)
  • Access Control

Meanwhile, optional libraries include:

Advanced Wireless Library

The Advanced Wireless Library can be incorporated into QualNet, EXata and NDT models, adding support for fixed and mobile WiMAX communications, based on IEEE 802.16d and 802.16e standards.

The library supports:

  • 802.16 MAC and 802.16e MAC
  • 802.16 PHY

IEEE 802.16 specifies multiple physical specifications including SC, SCa, OFDM and OFDMA. QualNet PHY802.16 only implemented the OFDMA PHY. OFDMA is similar to OFDM using multiple subcarriers to transmit data. However, while OFDM uses all available subcarriers in each transmission, different subcarriers could be arranged to different subscribers in downlink and each transmission could use a subset of the available subcarriers in uplink in OFDMA.

The mandatory features are implemented in the current implementation. It supports variable channel bandwidth, different FFT sizes, multiple cyclic prefix time, and different modulation schemes such as QPSK, 16QAM, and 64QAM with convolutional encoding at variety encoding rates.

The raw data rates of the OFDMA are functions of several parameters such as channel bandwidths, FFT size, sampling factor, cyclic prefix time, modulation scheme, encoding scheme and encoding rate. It can be up to 70 Mbps by using high grade modulation scheme with other suitable parameters.

Implemented Features

  • OFDMA physical model
  • Variety channel bandwidth support
  • Multiple FFT size support
  • Multiple cyclic prefix time support
  • Multiple data rates support
  • BER-based reception quality estimation
  • Subchannel SINR representation
  • Data rate and transmission range estimation

Cellular Library

The Cellular Library can be incorporated into QualNet, EXata and NDT models, adding support for GSM communications.

In the Abstract Cellular Model, a single base station serves a circular service area that is divided into multiple sectors, each of which is allocated with a certain amount of bandwidth. For each base station, several control channels are defined. A large number of base stations cover the simulated area and they are connected to a hub, the switch center, with wired links. The hub routes the control and data messages to/from the base stations. An aggregated node emulates the services originated or destined to nodes outside the simulated area. A gateway connects to all the BSs and the aggregated node. With help from HLR, the gateway routes the information flows between MSs or between MS and the aggregated node.

The GSM model in QualNet models the behavior of Mobile Stations (MSs), Base Stations (BSs), and Mobile Switching Centers (MSCs), and the “Um” (BS-to-MS) and “A” (BS-to-MSC) interfaces. The MSs can be located anywhere and can be mobile. The BSs and MSC are stationary. The GSM model allows multiple MSs, multiple BSs, and a single MSC in any scenario. Each BS is connected to the MSC by a wired point-to-point link.

Implemented Features

  • Configuration of MSC, multiple Base Stations, and multiple Mobile Stations
  • Standard band is supported (900 MHz Mobile Stations and Base Stations)
  • Cell selection and re-selection
  • Dynamic channel assignment and release
  • Location update
  • Call setup and tear-down
  • Handover (intra-MSC and inter-cell/Base Station)

UMTS Library

The UMTS Library can be incorporated into QualNet, EXata and NDT models, adding support for Universal Mobile Telecommunications System (UMTS) standards based on GSM technology.

The Universal Mobile Telecommunication System (UMTS) is a third generation (3G) mobile communication system that provides a range of broadband wireless and mobile communication services. UMTS maintains the global roaming capability of the second generation (2G) GSM system and its packet-switch mode enhancement (GPRS system) and provides enhanced capabilities. Compared with 2G telecommunication systems, UMTS is able to support multimedia services including graphics, pictures, and video communications, as well as voice and data at a higher data rate and with better quality of service. UMTS Model now supports 3.6 MHz bandwidth support.

There are three major categories of network elements:

GSM Core Network Elements: Mobile Service Center (MSC), Visitor Location Register (VLR), Home Location Register (HLR), Authentication Center (AuC), and Equipment Identity Register (EIR).

GPRS Network Elements: Serving GPRS Support Node (SGSN), and Gateway GPRS Support Node (GGSN).

UMTS-specific Network Elements: User equipment (UE), and UMTS Terrestrial Radio Access Network (UTRAN) elements. UMTS targets to build an all-IP network by extending the second generation GSM/GPRS system and using complex technologies including Code Division Multiple Access (CDMA), Asynchronous Transfer Mode (ATM), and Internet Protocol (IP). GPRS is the convergence point between the 2G technologies and the packet-switch domain of UMTS.

LTE Library

The SCALABLE LTE Library can be incorporated into QualNet, EXata and NDT models, adding support for LTE-based communications.

The Long Term Evolution (LTE) Model Library provides high fidelity simulation of 4G cellular networks based on the 3GPP Release 10 standards. It is built on the SCALABLE network simulator to provide system-level scalability, fast execution speeds and detailed MAC and PHY modelling. It includes models of nodes called eNodeB (Base Station) and UE (Mobile Station).

Implemented Features

  • LTE Evolved Packet Core (EPC)
  • LTE Layer 2

The LTE PHY model is based on the 3GPP 36.3XX architecture, and specifies E-UTRAN physical layer models. The main functions of the E-UTRAN PHY module are:

  • Downlink transmission/reception using OFDMA
  • Uplink transmission/reception using SC-FDMA
  • Coding/decoding, modulation/demodulation
  • Multi antenna operation (MIMO)
  • CQI/RI/PMI reporting
  • Power Control
  • Cell Selection
  • Random Access
  • Measurements
  • Hybrid Automatic Repeat Request (HARQ)
  • GTP
  • Download carrier aggregation
  • Wi-Fi Switchover

5G Library

The 5G Library can be incorporated into QualNet, EXata, and NDT models, adding support for 5G-based communications.

5G is the 5th generation mobile network. It is a new global wireless standard after 1G, 2G, 3G, and 4G networks that provides higher data speeds, ultra low latency, more reliability, massive network capacity, increased availability, and a more uniform user experience. 5G will be able to support all communication needs from low power Local Area Network (LAN) to Wide Area Networks (WAN), with the right latency/speed settings. The non-standalone (NSA) mode of 5G depends on the control plane of an existing 4G LTE network for control functions, while 5G is exclusively focused on the user plane. The standalone (SA) mode of 5G uses 5G cells for both signaling and information transfer. It includes the new 5G Packet Core architecture instead of relying on the 4G Evolved Packet Core, to allow the deployment of 5G without the LTE network.

The SCALABLE 5G Library is based on the 3GPP Release 15. The main features of the 5G models are:

  • Two deployment options: Option 3 (Non-standalone mode) and Option 2 (Standalone mode)
  • Two execution modes: High fidelity and high performance
  • 5G Core entities like AMF, SMF etc.
  • 5G Ran entities like 5G NodeB etc.
  • FDD and TDD modes
  • FR1 and FR2 frequency band
  • Hybrid Automatic Repeat Request (HARQ)
  • Carrier Aggregation of upto 16 carriers in DL and UL
  • Multiple Input Multiple Output (MIMO)
  • Millimeter Wave (MMW) propagation
  • Beamforming
  • Handover

Federation Interfaces Library

The Federation Interfaces Library can be incorporated into QualNet and EXata models, adding support for multi-simulator integration.

Multiple simulators can be used to simulate different aspects of the same scenario. The results of such a co-operative simulation can be more realistic and meaningful than those obtained by using any single simulator. The simulators interoperate with each other via data sharing to achieve a consistent representation of the simulation environment. Several standards, such as Distributed Interactive Simulation (DIS) and High Level Architecture (HLA), have been developed to facilitate data sharing among simulators.

High Level Architecture

High Level Architecture (HLA) is a specification that enables two or more software programs (usually simulation software) to interoperate. The software programs communicate with each other through a Run-Time Infrastructure (RTI) module, which implements the HLA interface specification.

Distributed Interactive Simulation

Distributed Interactive Simulation (DIS) is an IEEE standard for interfacing multiple simulation tools into a single, real-time simulation. The transport of information between simulators is performed using UDP and broadcast and/or multicast IP. Although superseded by HLA and IEEE 1516, DIS still remains popular for its simplicity of operation and the ease of creating a DIS interface. In HLA terminology, the collection of communicating simulations is called a federation and each simulation is called a federate. The object and interaction classes used in the federation are defined in a module called Federation Object Model (FOM). Information is exchanged between simulations using this FOM.

Socket Interface

Communication between a SCALABLE application and the external program is implemented over a TCP socket, with the SCALABLE application acting as the server and the external program as the client. Several types of messages can be sent between the two processes.

TIREM Propagation Library

The Terrain Integrated Rough Earth Model (TIREM) Library can be incorporated into QualNet and EXata virtual network models, adding support for terrain propagation effects.

TIREM is a propagation model which predicts the pathloss along the propagation path over irregular terrain at frequencies between 1 MHz and 40 GHz. Based on the geometry of the terrain profile, the appropriate propagation behavior is used to calculate the pathloss.

The core technology for TIREM was developed by Alion Science & Technology Corporation under contract to the US Defense Information Systems Agency. Alion licenses this core technology directly to customers for a fee. The SCALABLE TIREM Library is a connector and a “wrapper” for the Alion code providing tight integration into QualNet and EXata virtual network models. Customers who want TIREM functionality would purchase our TIREM Library and then contact Alion directly to purchase the core code. These two elements are then compiled together and linked into your QualNet or EXata simulation platform implementation.

Contact information for the TIREM core technology at Alion can be found HERE.

SCALABLE supports terrain data for both Cartesian and latitude/longitude coordinate systems. DTED and DEM, which both require latitude/ longitude coordinates, are the most commonly used.

Urban Propagation Library

The Urban Propagation Library can be incorporated into QualNet, EXata and NDT models.

The library supports propagation models for:

  • Automatic Model Selection
  • COST 231-Hata
  • COST 231-Walfish-Ikegami (COST-WI)
  • Okumura-Hata
  • Street Microcell
  • Street Mobile-to—Mobile
  • Suburban

When the Auto-select option for pathloss model is chosen, QualNet selects appropriate pathloss models based on the node location and urban terrain features. Different path-loss models are used according to their locations with respect to obstacles in the propagation path. QualNet allows selection of different model(s) for each source-destination pair and changes the models dynamically as the node positions change.

The COST 231-Hata propagation model is an empirical model that extends the Hata model to higher frequencies (1500-2000 MHz). It is a outdoor propagation model that is applicable to urban and suburban areas. The model is based on extensive measurement campaigns, and it is valid for flat terrain. The application of the COST-Hata-Model is restricted to situations where node’s antenna height is above roof-top levels adjacent to the node.

  • Environment is urban, suburban, or open area
  • Frequency is in the range 150-2000 MHz (recommended)
  • Antenna height of the base station is in the range 30-200 meters (recommended)
  • Antenna height of the mobile station is in the range 1-10 meters (recommended)
  • Distance between the base station and mobile station is in the range 1-20 km (recommended)

The COST 231-Hata propagating model is accurate within 1 dB for distances ranging from 1 to 20 km.

The model is capable of distinguishing between man-made structures and provides different formulation for small, medium, or large cities and urban, suburban, or open areas.

The COST 231-WI propagation model is a combination of the Walfisch and Ikegami models. It is an empirical model that is based on different contributions from members of the “COST 231 Subgroup on Propagation Models”. The model allows for improved path-loss estimation by consideration of more data to describe the character of the urban environment and it is applicable to metropolitan centers and urban areas. This model is statistical as no topographical data base of the buildings is considered.

Sensor Networks Library

The Sensor Networks Library can be incorporated into QualNet, EXata and NDT models, adding support for distributed sensor environments.

ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4 standard for Wireless Personal Area Networks (WPANs). ZigBee is targeted at RF applications that require a low data rate, long battery life, and secure networking. These networks are aimed at automation, remote control, and Wireless Sensor Network (WSN) applications. The IEEE 802.15.4 standard defines the physical layer (PHY) and Medium Access Control sublayer (MAC) specifications as the wireless communication standard for low-power consumption, Low-Rate WPAN (LR-WPANs).

Implemented Features

  • ZigBee Application
  • ZigBee (IEEE 802.15.4) MAC
  • Thread (IEEE 802.15.4) MAC (New)
  • ZigBee (IEEE 802.15.4) PHY

The SCALABLE ZigBee PHY is based on the IEEE 802.15.4-2006 standard. The PHY layer provides an interface between the MAC layer and the physical radio channel. It provides two services, accessed through two service access points (SAPs). These are the PHY data service and the PHY management service.

The PHY layer is responsible for the following tasks:

Activation and deactivation of the radio transceiver

Turn the radio transceiver into one of the three states,(i.e., transmitting, receiving, or off (sleeping)) according to the request from MAC sublayer. The turnaround time from transmitting to receiving, or vice versa, should be not more than 12 symbol periods.

Energy Detection (ED) within the current channel

It is an estimate of the received signal power within the bandwidth of an IEEE 802.15.4 channel. No attempt is made to identify or decode signals on the channel in this procedure. The energy detection time shall be equal to 8 symbol periods. The result from energy detection can be used by a network layer as part of a channel selection algorithm, or for the purpose of clear channel assessment (CCA) (alone or combined with carrier sense).

Link Quality Indication (LQI) for received packets

Link quality indication measurement is performed for each received packet. The PHY layer uses receiver energy detection (ED), a signal-to-noise ratio, or a combination of these to measure the strength and the quality of a link from which a packet is received. However, the use of LQI result by the network or application layers is not specified in the standard.

Clear Channel Assessment (CCA) for Carrier Sense Multiple Access with Collision Avoidance (CSMA-CA)

The PHY layer is required to perform CCA using energy detection, carrier sense, or a combination of these two. In energy detection mode, the medium is considered busy if any energy above a predefined energy threshold is detected. In carrier sense mode, the medium is considered busy if a signal with the modulation and spreading characteristics of IEEE 802.15.4 is detected. And in the combined mode, both conditions aforementioned need to be met in order to conclude that the medium is busy.

Underwater Communications Networks Library

The Underwater Communications Networks (UCN) Model Library can be incorporated into QualNet, EXata, and NDT, adding support for underwater acoustic and optical communications. The UCN Model will enable analysis of underwater network resiliency and self-healing performance, and provide communications visualization and communications system simulations. It provides high fidelity simulation of underwater acoustic and Free-Space Optical (FSO) communications.

Propagation models:

BELLHOP Acoustic Propagation Model: BELLHOP is a beam tracing model for predicting acoustic pressure fields in ocean environments. It allows for variations in the Sound Speed Profile (SSP) which refract the beam away from the straight line path. Reflection of the ray from the ocean surface and seabed are also calculated. It also optionally includes the geometric spreading and Thorp absorption processes. Since the beam tracing is quite slow to run, the properties of the environment are calculated prior torunningthe simulation in EXata. The values obtained from beam tracing are loaded into the simulation to providepathloss, arrival delay, and multi-path interference values.

Thorp Acoustic Pathloss Model: – Sound losses in the ocean are due to both spreading and absorption, both are modeled in UCN. In deep water, the spreading will be spherical, in shallow water the spreading will be cylindrical. In both cases, the loss will be in an inverse power of the distance between source and receiver. Absorption is due to effects of molecules dissolved in the water, this is frequency dependent, it results in an energy loss that is an exponential function of distance. The Thorp model of absorption includes terms for the most important modes of acoustic absorption and is valid for a range of frequencies between about 100 Hz and 50kHz.

Beer-Lambert Optical Pathloss Model: Light traveling through seawater is both scattered and absorbed. The coefficient of absorption and scattering are wavelength dependent and are also a strong function of the minerals dissolved in the water and particulate matter floating in it. These parameters are often referred to as the Intrinsic Optical Parameters (IOPs) of the medium.

Physical Layer Models:

The Acoustic PHY model is based upon the Abstract PHY model. The Abstract PHY model is described in Wireless Model Library.

There are many sources of sound in the undersea environment. In the frequency range used for acoustic communications, the dominant sources of noise are wind and shipping. Other ambient noise sources include turbulence, rain, and thermal noise. Anthropogenic sources also include communications devices, sonar, and explosions dues to seismic exploration. Marine life, most notably whales and shrimp, can also contribute to noise. When a signal is being received at an underwater communications node, the receiver will also pick up the ambient noise. This noise, combined with signals from other transmitters, and the inter-symbol interference, reduces the receiver’s ability to correctly discern the received signal.

The Optical PHY model is based upon the Abstract PHY model, which is described in Wireless Model Library. The Abstract PHY model is extended to include geometric factors of beam transmission and reception, an Optical Noise model, and a receiver model that supports Non-Return to Zero On-Off Keyed (NRZ-OOK) encoding scheme. The Optical PHY model uses a combination of an antenna pattern along with some geometric terms to determine the strength of the received signal. The antenna model supports the orientation of the platform that the transmitter or receivers are mounted on along with the mounting angle of the receiver relative to the pointing direction of the platform.

The Optical Noise model includes sources of noise from scatted sunlight and internal receiver noise. The sun is a powerful source of light, some light from the sun reaches the receiver due to scattering in the water. The single scattering model is used to approximate the sunlight entering the receiver, light is scattered out of the beam but not back into it. The light scattered into the receiver depends on the pointing direction of the receiver, the depth, and the IOPs.

Military Radios Library

The Military Radios Library includes models for:

  • Link 11
  • Link 16
  • Multi-Generator (MGEN) Toolset
  • Threaded Application
  • Compact Terrain Database
  • FCSC Radio Prototype

Details on this library are available upon request.

It’s important to keep in mind that the TIREM propagation library requires third-party code, while the military radios library may be restricted in terms of exporting in accordance with the International Traffic in Arms Regulations (ITAR) 22 CFR 120-130. You will need authorization from the US Department of State to sell military radios library modules.

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Integrated Planning of Tactical, Test Support, and Tactical Engagement Networks (IPT3N) can be used to automatically determine suitable tower locations based on the terrain and channel characteristics to create an LTE network layout to provide coverage to the area of interest while minimizing the amount of interference.

Key Features of EXata

Real Time Emulator

Seamlessly interface with other live equipment and applications

Cyber Testing

Test the resiliency of your network to Cyber Attacks

Network Digital Twin

Test your network in a low-cost, zero-risk environment


Model thousands of nodes with parallel execution

Model Fidelity

Models simulate accurate real-world behavior

Commercial enterprises, educational institutions, and governmental organizations around the world all depend on reliable, effective networks to deliver business-critical, mission-critical communications, and information. SCALABLE maintains a highly experienced group of technical professionals to support customers and projects of any scale and solve challenging problems with our advanced network digital twin technology.

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