MACSIM: an event driven simulation of an HF radio network

The authors describe MACSIM, a computer simulation developed to aid in the design and analysis of HF radio networks. They discuss MACSIM´s application to the network design process and provide the results of several stages of analysis, where MACSIM was used to evaluate preliminary network designs. MACSIM provides an effective and flexible tool for defining network structures, developing routing and message handling algorithms, and determining the effect of varying parameter settings and traffic loading. It is noted that the primary lesson learned to date in using MACSIM is that there is no obvious way to define in advance, with any degree of assurance, the optimal node/equipment/algorithms configuration for any nontrivial HF network. The experience has been that seemingly innocent assumptions can have dramatic impact, whereas apparently major modifications can produce only minor changes in terms of network performance. The power of MACSIM lies in its ability to lend the insight necessary to draw casual relationships between design options and performance results, and in its utility in the fine-tuning of designs that show particular merit