Distributed Interactive Simulation

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Distributed Interactive Simulation ( DIS ) refers to a data exchange standard defined in IEEE 1278 for controlling simulation systems.

Basics

DIS is used in professional civil and military simulations to optimize training (e.g. in traffic control centers, radar centers). Simulation systems networked by DIS can provide simulated situation information in real time, e.g. B. for synchronous control of radar simulators, and thus enable the users of the networked systems to perceive an identical representation of the environment in their respective simulator.

A DIS simulation object is referred to as an "Entity". Each entity must have a unique identifier (Entity-Id).

Data exchange

Communication via DIS is packet-oriented with UDP packets (multicast or broadcast) and TCP . The actual data is coded in binary. The byte order is in "network order".

The simulation participants connected via a Wide Area Network (WAN) or Local Area Network (LAN) can exchange the following information blocks ( Protocol Data Unit , PDU):

  • Entity State - denotes the position, course and travel as well as the sensor signature of a simulation target (e.g. strength of the radar echo), as well as type properties of the underlying simulation model,
  • Collision - allows you to evaluate whether two simulated objects (e.g. ships or aircraft) have collided.
  • Firing - a special, military variant of the Entity State PDU for simulating missiles and missiles .
  • Environment - data to simulate the environmental background, e.g. B. Landing echoes, clouds and rain (clutter).

The currently valid IEEE Std 1278.1 from 2012 contains a wide variety of PDUs that u. a. up to simulating minefields.

A PDU always contains the following components in the header:

  • Timestamp (time)
  • PDU type
  • version

advantages

  • Simple setup of a simulation
  • No management functionalities
  • Very fast
  • PDUs easy with Network Monitor as Wireshark interpretable
  • Low LAN network load through broadcast.

disadvantage

  • When implementing a DIS simulation, you have to program a lot of network code yourself
  • Possible routing difficulties between subnets (because of broadcasts), which can be compensated for by a so-called forwarder

successor

The High Level Architecture (HLA) , which many experts see as the improved successor standard of the DIS , takes a similar approach, but is object-oriented . HLA supports directed communication via a central administration point.