"The defence industry’s ‘grand plan’ for a ‘one size fits all’ SDR may not happen in its original form, but PA believes we should be planning for the adoption of software defined techniques" PHIL WHITE, PA EXPERT IN COMMUNICATIONS TECHNOLOGY
The defence industry’s ‘grand plan’ for a ‘one size fits all’ Software Defined Radio (SDR) may not happen in its original form, but PA believes we should be planning for the adoption of software-defined techniques.
SDR was heralded as the future of military tactical communications. Drawing on a combination of advanced technologies and well-defined standards, it promised lower through-life cost of ownership, together with enhancements such as faster, better and more robust wireless communications, including cognitive capabilities. A third benefit – emphasised by the defence vision of a Joint Tactical Radio System (JTRS) – was interoperability with other systems, enabling easier collaboration between allies.
The reality has been mixed. Various SDR programmes are happening in Europe and elsewhere, and software-defined techniques are being used in military and commercial worlds. However, JTRS has stalled and other radio procurements have taken place meanwhile.
At PA, we believe that ‘grand plan’ will be overtaken by ‘real world’. SDR is unlikely to fulfil the vision of an all-encompassing open standard delivering seamless interoperability at joint and combined levels, with lower whole-life costs. Certainly that won’t happen in the next 10 years.
Nevertheless, we believe that software-defined techniques remain highly relevant to defence – so where does SDR go from here?
SDR permits rapid, cost-effective development based on proven platforms and software work packages. Digital techniques also allow real-time adaptation and agility. These engineering advantages apply in both defence and commercial worlds, especially in lower volume (i.e. non-consumer) products.
SDR also allows for re-use of hardware and software platforms, enabling systems to be built on previous work in the same way that PC functionality is built on progress over the last 20 years or more.
Viability is increasing, thanks to reductions in the costs of SDR-relevant technologies such as field-programmable gate arrays (FPGAs) and digital signal processors (DSPs). For the first time, these devices are offering similar levels of radio systems performance to custom silicon – at manageable costs. While current SDR platforms may not be directly suitable for the next generation of waveform, they can reduce the level of engineering required compared with a completely new platform.
SDR is already in commercial use; most radio platforms have some element of it. Private Mobile Radio had SDR in VHF handsets as long ago as1990. Commercial cellular infrastructure manufacturers started standardising SDR interfaces for base stations more than five years ago. Cellular handset manufacturers, too, are talking about SDR, though power consumption will remain a blocker for many years.
As hardware becomes more powerful, SDR will become more attractive. We need to take Moore’s Law into account when specifying technology to be used in 2020: by then, electronics should be 100 times as powerful as now. That increasing power makes it possible to do more in software, and inevitably we will take advantage of that ability. NTT DoCoMo in Japan recently announced a demonstration of 1Gbps at walking speed, using multiple-in multiple-out (MIMO) technologies.
Defence can build on the economies of scale that commercial take-up creates. Customising standard platforms in software is now a reality.
Sadly, the dream that SDR is ‘future proof’ is more difficult to realise; we cannot realistically expect to design high-tech systems that will stay competitive over 20 years. Today’s SDR platforms won’t be capable for tomorrow’s waveforms. ‘Big bang’ programmes have a low probability of success – they are too expensive and their length means they get taken over by existing technology.
However, when the commercial world is moving so fast, this is less of an issue. Throwing away a hardware platform is much less expensive than 20 years ago. Commercial adoption and its spin-offs mean that military radio will use SDR, whether we plan it or not.
In the defence industry, we therefore need to put in place techniques for rapidly adopting, and where necessary modifying, commercial off-the-shelf (COTS) radio equipment.
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