The development of advanced mobile communications systems like 5G is not simply about delivering ever-higher data rates and increased network capacity. Now, more than ever, energy efficiency is becoming a vital consideration. Much has been written about the motivation for this, to reduce operational and ownership costs, as well as the means for achieving the performance improvements these new system architectures demand. Some of this bears repeating briefly below but underpinning the successful rollout of 5G networks in five or so years’ time is the expectation from equipment makers that key components such as power supplies will be reliably available in volume from multiple sources.
In the past, efforts to reduce energy consumption within the telecoms industry have been piecemeal. The philosophy we now have to comprehend is the need to address the whole network, looking at all aspects of infrastructure, such as base stations, servers and routers. This isn’t just about improving the energy performance of new equipment, where the latest designs, using more efficient processors, FPGAs and ASICs, can achieve significantly reduced power consumption. The installed equipment base also needs to be taken into account. Here intelligent energy management software, benefitting from traffic analysis and mapping, can be used to optimize the network and ensure equipment is active and available where it is needed but it is powered down when it isn’t.
The concept of a software-defined architecture, which has already pervaded the router and data center industry, will be essential as telecoms networks continue to evolve. Certainly 5G, as the next generation of mobile network, will see an increase in the virtualization of network hardware and an ever-larger cloud computing capacity. 5G will also need to deliver a higher network-energy performance, reducing the power required to transmit data by employing an ultra-lean ‘only transmit when needed’ design approach.
All this is well and good but managing energy usage using software algorithms is only going to work if we can match the potentially wildly varying loads presented by the network equipment with power supplies that can respond equally flexibly and efficiently to this dynamic demand. This immediately implies the need for what is being referred to as a software-defined power architecture (SDPA) that can adjust the power profile to the traffic. This in turn requires digital power supplies, i.e. power supplies where the feedback path from the output load to the input supply is digital, enabling a much faster, realtime response to changes in line and load conditions while also operating at the highest possible efficiency.
The whole premise of digital power has been well documented elsewhere. Similarly the concept of distributed power, which implements the final conversion to the ever-lower voltages required by modern electronic circuits at the point-of-load, avoiding I2R power losses in backplane and circuit board wiring and thus further improving power system efficiency. There are now a number of manufacturers who offer digital power solutions but the concern from equipment makers is their need to be able to source truly compatible power supplies from more than one vendor.
In the past, multi-sourcing of analog power supplies was a relatively straightforward matter, requiring mechanical and electrical compatibility. Industry bodies like POLA and DOSA have helped standardize mechanical requirements in terms of dimensions, board footprint and pin-out, leaving buyers to simply ensure electrical equivalence with regard to input and output voltages and currents. Unfortunately digital power poses a whole new level of functional compatibility considerations. Even the use of an open-standard communications protocol like PMBus does not guarantee interoperability because digital controllers from different manufacturers do not necessarily interpret commands the same way. In part this is because PMBus allows two data formats, Linear and Direct, with unique exponent values. So setting Vout with one controller could result in the intended output of 1.2V while another controller might output just 1.0V or 1.6V, or even 1.8V!
Given that 5G is expected to reach the market in five years, systems architects already face a huge challenge in addressing software interoperability, an issue that is very much on the critical path. Similarly, the need for procurement managers of companies developing 5G equipment to secure their supply chain is rapidly becoming business critical.
One answer to these challenges is provided by the multiple-sourcing initiative established by three leading power supply manufacturers, CUI, Ericsson and Murata. The Architects of Modern Power (AMP) Group has formulated standards to address many of the common requirements for digital supplies, both intermediate bus converters (IBCs) and point-of-load (POL) DC-DC converters. With at least two of its member companies having introduced products to meet each of these standards, supply chain security is ensured with true plug-and-play compatibility. This close collaboration, both within the Group and with its customers and common component suppliers is unique in the industry.