Almost a decade ago, industry experts had predicted that the prevalence of the Internet of Things (IoT) would have been widespread by now – to the point of almost being ubiquitous.
Though nobody doubts that IoT technology is going to have a vital role to play in digital transformation, there are still issues to overcome before this happens. If the early forecasts about IoT pervasiveness had been correct, then the number of nodes in operation would have been in the region of 50 to 65 billion by this stage. In reality, it has still only reached a fraction of those numbers – with most estimates (IoT Analytics and Statista among them) putting the current total at around 12 to 13 billion. Shohei Kawanaka, Product Manager, Europe, Connectivity Module, Murata discusses.
Factors affecting IoT uptake
The influence of several different dynamics has been responsible for slowing down the progression of IoT technology, in terms of putting nodes out in the field. Among the most prominent of these are:
- There will normally be a considerable amount of components needed in each IoT node. This can prove problematic in situations where space constraints need to be taken into account. Nodes need to be kept as compact as possible while ensuring this does not impact their performance, functionality, or operational longevity.
- Next there is the capital expenditure (CAPEX) involved. Though the bill-of-materials (BoM) costs relating to a single IoT node may not seem that great, they will become a concern when rolling out networks comprised of large numbers of these nodes. For these reasons, designs must be as streamlined as possible – ideally with only a few constituent parts needing to be incorporated.
- As well as CAPEX, there is the operational expenditure (OPEX) to factor in. Once the nodes that make up an IoT network have been put in place, there can still be significant running costs involved if technicians must be called out to undertake any form of maintenance work.
- The generation of electronic waste (e-waste) has already been identified as a major worry – and having tens of billions of IoT nodes deployed around the globe could add to this substantially. Steps must be taken to combat the build-up of discarded materials associated with IoT nodes over time.
Creating a new power paradigm
The powering of IoT nodes affects all four of the factors just outlined. A sizable amount of board space needs to be allocated for accommodating their Li-Ion battery cells. In addition, these batteries have both a CAPEX and an OPEX, with the OPEX side normally being of the greatest consequence. Depending on the application, in particular, the number of times a day that a sensor acquires data and how frequently the wireless transceiver has to communicate with its assigned hub, the time over which an IoT battery cell will last is likely to be somewhere between 18 months and 2 years. The nodes themselves might, however, remain in operation for 10 or possibly 15 years. This means that after IoT nodes have deployed, they will need to be fitted with replacement batteries on several occasions throughout their lifespan.
With networks potentially comprising many thousands of nodes, the logistical effort that replacing batteries will represent is going to be huge – calling for some staff to be assigned to this task full-time. Under such circumstances, OPEX anxieties will discourage IoT roll-out. Also, if heavy workloads mean that batteries are used up quickly, then on top of the OPEX, the CAPEX could likewise be restrictive. Finally, if not correctly disposed of, the substances found in these batteries will leach into the soil and water – causing harm to plant and animal species.
Making IoT more sustainable
IoT deployments that are dependent on battery power will have acute drawbacks, concerning the costs involved and how delicate ecosystems are affected by pollutants. For this reason, the use of energy harvesting is being seen as providing a better foundation on which to build IoT networks, with power being drawn from the surrounding environment.
By having an energy harvesting-based strategy for powering IoT nodes, battery usage can be taken out of the equation. This will nullify the CAPEX and OPEX associated with buying and then replacing batteries. It also means that far less e-waste will be produced through IoT activities. There are, however, certain matters that need to be addressed if this approach is to prove fully effective.
Challenges with energy harvesting technology
If acquiring energy from sustainable sources that surround deployed IoT nodes is to see wholesale adoption, then certain improvements in the hardware itself will be needed. In particular, there must be a focus on making enhancements to the power management ICs (PMICs). Through these devices, the whole energy harvesting process is managed. They decide what amount of electricity needs to go to the IoT nodes for it to fulfil its functions at that time, as well as how much can be placed into storage for utilisation later. Certain characteristics currently make PMICs far from ideal in an IoT context. The two most prominent of these are that they lack adequate conversion efficiency and that they call for the inclusion of a lot of passive components.
On top of all this, the wireless modules that can be incorporated into IoT nodes are generally too bulky, power-hungry, and costly for them to be truly practical. Then there are issues related to the subscriber identity modules (SIMs) needed for cellular IoT. Traditional SIMs take up space and draw on precious power reserves. They have downsides from an ecological standpoint too. The plastic credit-card-sized carriers in which SIMs are held become another source of e-waste when they are disposed of. This is why other ways of keeping SIM information are now being explored.
Finding an answer to the IoT conundrum
Through a joint effort between engineering teams at Murata, Deutsche Telekom, and Nowi, it has been possible to introduce a platform that will transform IoT node development. It will facilitate the development of nodes that are energy autonomous, while not drawing too much electricity, being limited in their performance capabilities, having too great BoM costs, or being too big that there will be restrictions on the places in which they can be implemented.
The Autonomous Cellular LPWA Development Solution (ACDS) platform, formerly known as the Autonomous NB-IoT Development Solution (ACDS) platform, consists of three main elements. Firstly, there is a compact form factor Murata dual-mode cellular IoT module. This is capable of delivering downlink rates of 26.15kbps (for NB-IoT) and 1Mbps (for Cat.M1) downlink data rates while maintaining high levels of power efficiency. It has extended discontinuous reception (eDRX) and power saving mode (PSM) features which keep its energy consumption to an absolute minimum.
Alongside this is the nuSIM technology provided by Deutsche Telekom. Here, board real estate has been reduced and the generation of plastic waste avoided by integrating subscriber information directly into the wireless module. As well as saving space and curbing environmental harm, nuSIMs are around 35% faster at connecting to a network than conventional SIMs, thereby requiring still less electricity. There is no need for ongoing SIM presence detection, which gets rid of another electricity draw.
Figure 1: ACDS IoT development platform
The final piece to complete this puzzle is the Nowi NH2 PMIC, which is optimised for use in IoT deployments relying on energy harvesting instead of batteries. This device is responsible for managing energy transfer to the ACDS platform from its renewable power source (which is a small photovoltaic panel). The threshold at which input power can start being dealt with is very low (only 10µW), meaning that energy can be extracted from relatively poor levels of illumination. By having a maximum power point tracking (MPPT) settling time of no more than 1s, the NH2 PMIC achieves an impressive 80% average power conversion efficiency figure. As it uses capacitive converting, much fewer passive components are needed than for other energy-harvesting PMICs. The upshot of this is, once again, that less board space is taken up and nodes can be smaller.
Energy autonomous capabilities
With just 3000lux of light (which would be expected even on a fairly cloudy day) incident on the ACDS solar panel over a 6-hour duration, a 1.1mA average charging current will be produced. This is enough to support up to 60 NB-IoT transmissions per day. IoT nodes developed using the ACDS platform will therefore have ample capacity for the vast majority of prospective scenarios.
The OPEX, CAPEX, and environmental impact of IoT implementations simply cannot be ignored. Furthermore, if not adequately addressed, the situation is only going to become more serious as the size of networks increases. Taking an approach that has been discussed in this article, where IoT nodes are developed in a way that is no longer restricted by battery inclusion but is instead based on energy harvesting, complemented by smaller wireless hardware and the convenience of SIM integration, a multitude of benefits can be derived. It will allow a rationalising of BoMs, the lower total cost of network ownership, and far greater sustainability by stemming e-waste pile-up.
There is also the prospect of making IoT network deployments viable in a more extensive range of different use cases. It will help to bring the investment needed within reach of more commercial enterprises, utility companies, municipal governments, and many other potential stakeholders.
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