ENVIRONMENT
MODELS
PSI has built a number of GSS models
to investigate the effects of electromagnetic phenomena when multiple waveforms
impinge upon an antenna. These models
are particularly useful when performing interference analyses, or analyzing the
effects of mobile radio communications in rough terrain and foliage. Fast algorithms are used to speed
calculation of path loss based on digitized terrain and foliage data so that
large numbers of transmitters and receivers can be studied to determine the
effects of dynamic interference, mutual interference, and motion of platforms.
Fast
Line-of-Sight (LOS)
A system with very fast algorithms
to determine optical line-of-sight (LOS) between two points based on digitized
terrain elevation data. A special
hierarchical terrain database is built by preprocessing standard data to
support the fast algorithms for long paths over large land areas (1000s of
kilometers on a side). The hierarchical
terrain database is created from U.S. Government digital terrain data using
PSI's Terrain Data Management System (TDMS).
LOS can be ground-to-ground, air-to-ground, or air-to-air. Because of its speed, this system is
especially suited to real-time simulations requiring large numbers of LOS
determinations in a short time period, such as when modeling sensor systems
that view large numbers of objects in a dynamic,live equipment test
environment.
Fast
Propagation Prediction System (FPPS)
FPPS is a set of models for predicting
propagation path loss over large land areas of rough terrain. This system has been designed to extract
terrain feature data using fast algorithms and a special hierarchical terrain
database. The terrain feature
extraction algorithms have been designed to support electromagnetic propagation
models including modified versions of
the TIREM, Longley-Rice, and Longley-Reasoner point-to-point
models. FPPS provides deterministic
profiles and statistical characterization for each specific path as needed, with
model selection and adjustments determined by the path and frequency range of
interest. FPPS is suited to any kind of
simulation requiring point-to-point propagation path loss predictions which
account for specific terrain or foliage effects. Paths can be ground-to-ground or air-to-ground. This model also uses PSI's foliage loss
model described in the next section.
FPPS spans 20 MHz to 20 GHz.
FPPS provides high speed performance
when working with areas about 1000 X 1000 Kilometers. These speed enhancements are achieved by preprocessing the
terrain data and storing it in main memory for quick retrieval.
PSI's foliage loss model accounts
for antenna and tree height, type and density of forest, and leakage mode (over
the trees) using a modified Head/Tamir type model. PSI's foliage database is the same format as that of the terrain
data.
High
Frequency (HF) Propagation and Interceptibility
The High Frequency radio link
interceptibility model utilizes the IONCAP system for HF propagation path loss
prediction developed by the Institute of Telecommunication Sciences (ITS), U.S.
Department of Commerce. Low Probability
of Intercept (LPI) Performance is measured in terms of the surface area over which
the selected radio link can be intercepted by a designated type of
interceptor. HF-FPPS spans 2-30 MHz.
PSI has built a number of radio
models that include generic features as well as specific detailedspread
spectrum implementations. Radio
submodels include sensitivity, signal processing attenuation of partially
correlated signals due to frequency hopping and pseudo-noise coding, error
detection and correction coding, time dispersal coding, filtering, hard and
soft decision receiver operational characteristics, etc. These models are easily modified to
accommodate different radio specifications or laboratory data. Included in this category are models of
JTIDS/MIDS, SINCGARS, EPLARS, Link-11 HF, and UHF SATCOM.
Several antenna models have been
developed by PSI, including omnidirectional and directional on moving
vehicles. Different lobe patterns can
be characterized in detail to allow the measurement of received signal from
transmitters, including interference.
Directional patterns can be specified in both the vertical and
horizontal planes, or three-dimensionally.
These antenna models are amenable to supporting active aperture design.
INTERFERENCE
MODELS
These models provide the facilities
to deploy dynamic interference with specific modulation techniques, and time,
frequency, and power control.
Interferers can emit waveforms, which are partially correlated to the
radio receivers, to investigate the effects of different receiver designs,
including various spread spectrum techniques.
They can be placed on moving vehicles with variable speeds and
directions that follow prescribed rules.
NETWORK
CONTROL MODELS
GSS models have been
built to implement the decision making process in Network Control Centers. These models provide for the decision
processes that change operational status of communication resources including
nodes, links, transmitters, frequencies, time-slots, etc. The decision processes relative to movement
of communication resources or users are also implemented in these models.
MOBILE
TELEPHONE - RADIO ACCESS UNIT MODELS
Detailed models of
radio access units and mobile subscriber radio terminals have been built using
GSS. These detailed models implement
the existing radio protocols between the access units and the mobile radios. These models contain the scanning process to
find either a free or a specific channel, and the affiliation contention
processes encountered when the mobile radios lose contact with their access
units. These models are normally used
in conjunction with PSI electromagnetic environment models or connectivity
simulation scenarios.
SWITCH, ROUTER & GATEWAY MODELS
PSI has built a large number of
different switch models using GSS.
These models contain various different signaling and routing schemes, as
well as different features of communication switches, with optional queues,
processors, and buffers.
Routers
PSI has built GSS models of various
routers using various forms of adaptive routing or standard routing tables to
support network analyses. Schemes for
building routing tables adaptively, including the use of routing update
messages or using special techniques have been implemented. Models include detailed protocols and
algorithms as well as numerous other system features.
PSI has built GSS models of various
central node switches using circuit or ATM backbones, and various forms of
adaptive routing or standard routing tables to support backbone network
analyses. This model includes the
detailed protocols and algorithms as well as numerous other system features.
Extended
Node Switches
There are GSS models of extend node
switches, including circuit, packet, and ATM.
These models incorporate adaptive routing algorithms or tables for
routing that are adaptively updated, and provide an interface with smaller or
larger switches using the same routing scheme to evaluate system performance of
large numbers of nodes handling many subscribers, including mobile radio
subscribers.
Access
Network Switches
These provide detailed models of the
access network switches, including large extension nodes, small extension
nodes, and radio access units described above.
PSI has developed packet switch models with detailed protocols modeled
along physical lines for ease of making rule changes and evaluating different
routing algorithms, as well as assessing performance relative to data system
requirements.
Access
Network Switches
These provide detailed models of the
access network switches, including large extension nodes, small extension
nodes, and radio access units described above.
PSI has developed packet switch models with detailed protocols modeled
along physical lines for ease of making rule changes and evaluating different
routing algorithms, as well as assessing performance relative to data system
requirements.
These provide detailed models of gateways between
different link and protocol implementations.
Such models include Joint Range Extension (JRE) Gateway and Protocol for
passing TADIL-J messages through IP connections.
Host
Data Traffic
GSS models to create data traffic
based on detailed representations of user characteristics that define
throughput and response time requirements.
Models provide for generation of specific messages depending on host
state, scenario activity, response required, incoming messages, etc. Host transmission queues are modeled to
provide for acknowledgments, or to hold messages for prescribed periods while
links are down. Hosts can move based on
messages received or scenario states.
Hosts can be turned off and on to reflect planned movement, equipment
failure, and maintenance periods. Host
traffic models can represent aggregated users and local area networks.
Simulations
of complex mission-oriented scenarios involving large numbers of interacting
air, sea and ground platforms require realistic traffic to test network designs
and communications in support of mission success. Message string models support transmission and exchange of
messages, e.g., mission-oriented message strings, between platforms. Event models are used to stimulate
transmission of messages in synchronization to mission dynamics.
Telephone
Subscriber
GSS models specific to the
characteristics of individual telephone subscribers based on various types of
user requirements. These models provide
for call intergeneration times and call duration. They also provide for destination busy, priority, call retry due
to busy, or network failure (which also depends on call duration). These models are designed specifically to
determine the transient effects on network capacity due to changes in the
network environment.
Aggregated
SubscriberS
A GSS model to consolidate multiple individual subscribers at a switch point such as a node or an access unit while maintaining the data for each subscriber as to source, destination, and other individual statistics. This model provides for many types of subscribers and scenario specific or stochastic representation of their call statistics.
SENSOR
MODELS
PSI has built a variety of sensor models including radars. These can be airborne or ground based and can incorporate track management logic. Central to these sensor models is PSI's Fast Line-of-Sight (LOS) system which uses detailed digitized terrain databases. The Fast LOS system supports real-time simulations where many thousand LOS determinations are performed every minute. This allows modeling of many sensors networked together, seeing thousands of objects.
HOST
PLATFORMS (GROUND, SURFACE, AIRCRAFT & SATELLITE VEHICLES)
A variety of vehicle platform models
has been developed to be used in dynamic simulations containing hundreds of
aircraft and ground vehicles. These
vehicles can include "smart" controllers that make turns and follow
road networks or flight patterns that change as the simulation unfolds. Built-in decision processes are used to
guide these vehicles and set directions that depend on the sequence of
simulation events as they occur. Platform
models support full 6-degrees of freedom in their motion, which is required for
simulation of tactical communications dynamics.
C4ISR simulations and modeling requires good sensor models. Sensor models available in GSS include Unmanned Ground Sensors (UGS) model, SIGINT UAV Sensor models, SIGINT Model Suite, Sensor Coverage analysis model, Sensor Interface and Management models, Sensor Communications models including power consumption, Sensor Placement Optimization models, Two-Tier Sensor Fusion, and Graphics Spot Reporting and Alerting models. Models for different types of sensor modalities and capabilities can be rapidly built with GSS.
Examples
of GSS models in this category include Opposition Ground Emitter models, Radar
models, Jamming models, Missile models including Pedistal Mounted Stinger
Missile, and Smart Bomb model for Small Bombs.
GSS model hierarchies provide mechanisms that promote easy reuse and
extension of existing models such as those for weapons and threats.
Realistic
simulations of complex military scenarios require models for the Command and
Control (C2) processes and executive models higher-level players/actors. PSI has a number of models of C2 processes,
and models for Weapons Control, and models of Subscribers.
DYNAMIC SCENARIO MODELS
Most
military operations involve a large variety of moving and static platforms
assigned to different missions employed over one or more geographic areas. Scenario development can be a complex,
time-consuming processing. PSI has
evolved GSS models to support interactive creation (and execution) of large,
complex scenarios involving hundreds and thousands of platforms. GSS scenario development models simplify
placement of ground platforms, and creation of movement paths and assignment of
platforms to these paths. “Deployed”
platforms can then be “equipped” with radios, jammers, etc.. Communications relays can be deployed as
needed. Dynamic motion of platforms
supports 6-degrees of freedom, which is important for testing tactical
communications links of airborne platform.
A growing collection of GSS-based protocol models is available. Examples of protocols included in this model collection are: TCP/IP, UDP, Service Location Protocol (SLP), Link-16, MIL-STD 188-220A, MIL-STD 188-184, Joint Range Extension (MIL-STD 3011), CLNP, SNMP, FTAM, Robust Transmission Protocol. Many other protocol models are available.
Visualization
can be a vital capability for understanding model validity, and for
comprehension of complex simulations.
The Run-Time Graphics (RTG) capabilities supported by GSS and associated
models support a wide range of powerful visualization abilities. Examples of enhanced visualization
capabilities include 2D, 3D and Whole Earth models, Terrain and Terrain Contour
visualization models, Dynamic platform motion models, Satellite visualization
models, dynamic RF and network connectivity visualization, RF
coverage/footprint models, dynamic entity state visualization. Furthermore, GSS/RTG visualization supports
the unique ability to dynamically interact and modify models in a running
simulation!
Getting
data into and from models and running simulations is extremely important. GSS provides a wide range of inputs and
outputs. Examples of inputs include
XML, TCP/IP, Shared Memory, System Clock, GIS Data, ARC Shape Data, NGA (NIMA) terrain data, GUI panels and
various file formats. Examples of
output capabilities include XML, HTML, TCP/IP, PowerPoint, Excel, PNG Images,
ARC Shape data, Shared Memory, GUI panels and a variety of file type. In support of distributed simulations,
capabilities include HLA, DIS, TCP/IP, SLP and SNMP.