Carrier frequency allocation in FDMA military SATCOMs

Abstract

Tactical military SATCOMs require a sophisticated balance between efficiency and resilience. Ideally, this balance needs to be flexible and dynamic, so as to adapt as demands (and threats) ebb and flow. Automation is seen as the key to providing the flexibility to migrate SATCOM band plans between rapidly evolving scenarios. Efficiency and revenue maximisation are often the key drivers in commercial satellite systems, nevertheless carrier frequency allocation techniques developed for civilian systems can be usefully employed in military systems, provided optimisation is extended to address resilience and support flexibility. Key factors in optimising frequency plans in multi-satellite, multi-beam, multi-terminal, multi-modulation systems are frequency re-use, compliance with satellite and ground station regulation and co-ordination agreements and, critically, the control (or mitigation) of intermodulation products. Significant differences between military and civilian systems are the likelihood of electronic attack and the widespread use of spread-spectrum (particularly frequency hopped) systems, which typically trade spectral efficiency for increased robustness and reduced probability of detection. We describe carrier frequency assignment approaches for SATCOM systems. Techniques studied include the use of meta-heuristic algorithms, such as genetic algorithms and tabu search, and quasi intermodulation-free schemes based on Golomb rulers, as well as conventional heuristic approaches such as variants of the insertion/deletion method.