Back in 2009, I wrote about advances in underwater wireless communications and the challenges involved in connecting underwater sensors and autonomous vehicles. At the time, much of the discussion centred on underwater acoustic sensor networks, where limited bandwidth, long propagation delays, multipath and high error rates created challenges very different from those encountered in terrestrial wireless networks. Nearly two decades later, many of those fundamental challenges remain. Earlier this year, I looked again at underwater communications and the challenge of ocean connectivity, including the growing interest in heterogeneous networks combining acoustic, optical and, where practical, radio technologies. There is unlikely to be a single underwater equivalent of Wi-Fi or cellular connectivity. Instead, different technologies occupy different parts of the range, data-rate, latency and power-consumption trade-off. A new research project from the University of Florida adds another i...
Moving public-safety communications from narrowband systems such as TETRA to 4G and 5G is rarely a straightforward technology replacement. Coverage has to be at least as good as the system being replaced, resilience requirements are considerably higher than those of an ordinary commercial mobile service, and migration can take many years. Iceland provides a particularly interesting example of how this transition might be approached. A presentation at Critical Communications World 2026 outlined Iceland’s current thinking for its next-generation critical communications system. Rather than immediately building a completely separate nationwide 5G network or simply relying on ordinary commercial mobile services, the emerging model combines dedicated spectrum, a dedicated core and MCX capability, and shared hardened radio infrastructure. The starting point is Iceland’s geography. The country covers around 103,000 square kilometres, around 75% of which is uninhabited highland and roughly 10%...