RDRN System Emulation


Emulating the Rapidly Deployable Radio Network (RDRN) environment enables the RDRN software developers to test and evaluate large RDRN configurations in the laboratory under controlled and repeatable conditions. The Emulation Manager (EM) emulates and displays the environment that the RDRN computers use in determining network topology and routing. The laboratory RDRN emulation system consists of:
The portion of the system that the emulation manager emulates consists of:
In an emulation the EM acts as the GPS receiver for each RDRN node and propagation medium for the Orderwire packet radio transceiver and the high bandwidth radio links. Establishment of high bandwidth (HBW) radio links between nodes is also emulated by the EM and ATM switch(s). Loss of signal between nodes due to range for Orderwire and HBW and terrain blockage for HBW communications is emulated by the EM.

During an emulation the EM displays node position and HBW connection status between nodes using a graphical display.

In the real world RDRN nodes move about over terrain and use GPS to determine their position on the terrain. They receive NMEA 0183 format GPS messages containing the current time, their latitude/longitude location, speed, direction and height from a GPS receiver over a serial link. In the emulation environment RDRN nodes receive GPS messages in the same format with the same information from the EM over a UDP socket. The information to put into the GPS messages for each node in an emulation is determined by the EM using a predefined node movement scenario file and digital elevation maps.

Orderwire messages in the real environment are transmitted and received via packet radio transceiver connected to an RDRN over a serial link. In the emulation environment Orderwire messages are transmitted and received by the nodes via the EM over UDP sockets. Propagation of the Orderwire packets is emulated by the EM by broadcasting an Orderwire packet datagram sent to the EM by a node to all other nodes within an emulated range limit (~90 km) of the transmitting node. The EM does not require any knowledge of the structure of the Orderwire packets in the UDP datagrams.

In the real environment two neighboring RDRN nodes electronically steer HBW radio beams at each other to establish an ATM connection over the radio link. For the emulation case two neighboring nodes send a request to the EM to establish a physical ATM connection between them through the ATM switch(s). This emulates the radio connection between the nodes. The nodes then establish a 'virtual' ATM connection over the physical ATM connection. The establishment of the 'virtual' ATM connection is equivalent to the establishment of the ATM connection in the real environment. The nodes can also request that the EM delete physical ATM connections.

The RDRN nodes send the requests to the EM for physical ATM connections utilizing UDP sockets and a emulation management request protocol developed for this project. The EM controls and statuses the ATM switch(s) through SNMP commands over Ethernet.

The EM monitors the range between nodes as the emulation runs. When two nodes request a physical ATM connection the EM creates the connection if the nodes are within the HBW range (~ 9km) and the terrain does not block line of sight (LOS). If two connected nodes exceed the HBW range or loose LOS the EM deletes the physical ATM connection to emulate the loss of LOS or exceeded range.

As the emulation manager runs it displays the positions of the RDRN nodes on a 2D display of the terrain covered in the emulation scenario. MN nodes are displayed as filled circles while the MAP nodes are displayed as squares. Each node is displayed in a unique color. As the emulation progresses the displayed symbols of the nodes are moved on the 2D display to represent the movement of the nodes in the emulated environment. The user may enable display of the past path of the nodes. The node paths are displayed as solid grey poly lines.

When any two nodes are connected with a physical ATM connection the EM displays the connection with a solid black line between the nodes. As the nodes move the connection moves with the nodes. The user may enable display of past ATM connections. They are displayed with a dotted grey line.

The emulation runs in real time. The user is able to pause and continue the emulation. Pausing the emulation prevents the EM from sending GPS messages to the nodes. When the user continues the emulation the EM restarts sending GPS messages where it left off.

An auxiliary window may be created by the user to display statistics about the nodes. The node symbol used in the 2D display is shown and matched with its scenario name, type (MN/MEP), speed, direction, height, latitude/longitude and range to other nodes.

An auxiliary window may be created by the user to display current connection status. For each node the connection status to other nodes is displayed. The status consists of the PVC of the physical connection, name of connected node, number of cells sent and number of cells dropped.

Screen Shots

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Last Update: October 25, 1999 02:00pm (GMT-0600)