The internet of things (IoT) holds much promise for making our world smarter, more connected, and efficient. However, if it’s going to fulfil this promise then the technology behind it needs to exhibit similar characteristics. Location-awareness is key to the success of the IoT and to that end Imagination is announcing Ensigma™ Location, a family of high-performance and low-power IP solutions for Global Satellite Navigation Systems (GNSS).
GPS vs GNSS
While many people will not have heard of GNSS they will be familiar with GPS, typically through a navigation software, using either a receiver in a smartphone, a dedicated stand-alone device or built into their car. If you’re wondering what the difference is between GNSS and GPS, the answer is none. Global Satellite Navigation Systems is a standard term that encapsulates the various flavours of satellite navigations systems from around the world, and GPS is simply the best known – the ‘Hoover’ of the GNSS world, as it were.
GNSS comes in various flavours known as ‘constellations’: the US Global Positioning System (GPS), the Russian GLONASS system, the European have Galileo and the Chinese BeiDou. It also includes several Satellite-Based Augmentation Systems (SBAS) including WAAS and EGNOS.
Ensigma’s GNSS Location IP supports all these services – and which of these you choose to support will be a critical decision to make if you are to reap the low-power consumption rewards that the Ensigma IP delivers.
However, the issue with GPS receivers used for car or pedestrian navigation is that they are designed for continuous tracking. That’s necessary, as to be able to make immediate decisions when driving walking or cycling you need to know as precisely as possible where you are on the road at any given moment. However, this requires continual communication with satellites and has the downside of using a lot of power. It’s why your phone heats up when you’re using GPS and why your battery rapidly drains.
That’s not a good fit for the IoT, where devices are needed to be out in the field, (often literally), for years at a time, without the ability to be connected to power or recharged. And it might not be in difficult reach rural areas. Users might want to attach a light, long-lasting tracking device to a pet or use a smartwatch that tracks their run but doesn’t need to be charged every day.
To be practicable then, these devices need to run on sub-milliwatt power budgets and this means taking a different approach to designing GNSS for the IoT.
Locations and the IoT
Location capabilities in devices are important for many reasons. In smart cities, it’s used for infrastructure location – enabling engineers to precisely find a streetlamp or mobile mast that needs working on, perhaps if a light or a node has failed. (Yes, street poles may not move, but the precise location of every piece of infrastructure is often unknown – and if it’s moved by the time the engineer gets there, then you’ve got bigger problems).
Location is also widely used for asset tracking. In agriculture, the prized asset is livestock, (which does move), and locating them quickly is critical for the farmer. We’re happy for Daisy to roam a certain distance but there will come a time when you need to know where she and her family are.
Bike sharing schemes are popular in many cities around the world and location devices could help individual bikes to be found quickly and efficiently.
Equally, location is also required to monitor the supply chain to track deliveries to boost security and enhance customer information.
However, what’s notable about all these examples is that unlike a car GPS device, they do not require continual, constant tracking. The location data is only required when there is a specific need.
Ensigma’s Location IP takes advantage of this to provide an ultra-low-power solution for these specific markets. How it achieves this is through a technique that we dub ‘snapshot’.
Taking a snapshot
A major contributor to the power consumption of a GNSS device is its use of radio frequency (RF), which it needs to activate when tracking satellites. In a car navigation device, the satellites are tracked for tens of seconds at a time. However, this is not required for the use cases Ensigma IP is targeting. Instead, a ‘snapshot’ technique is employed, where a short recording of the satellite signal is acquired as rapidly as possible, and then processed ‘offline’ after the receiver is powered down. The faster this is done, the sooner the RF can be switched off. This snapshot technique, also known as ‘capture and process’, can reduce RF power usage by more than 99.5%.
Another area where Ensigma Location IP makes its power gains is in its ‘Time to First Fix’ (TTFF) performance. Returning to our car navigation example, a very rapid time to fix is required here as you can’t navigate your way home until your GPS device knows where it is, so it needs to acquire satellites as quickly as possible. This is again achieved by consuming power. However, for the IoT market, the ‘time to fix’ is less time pressured. As such our total TTFF (between 19 and 31 seconds for signals better than -147dBm depending on the number of constellations supported) still offers industry-leading performance while conserving power as much as possible.
As an IP solution, Ensigma’s GNSS Location enables customers to integrate location capabilities into their own IP, rather than using a third-party companion chip. This pays dividends by both reducing power consumption and thanks to very low silicon area it lowers costs through a reduced bill of materials (BoM). Through its use of cutting-edge snapshot technology, it can offer ultra-low-power location capabilities that usher in a new wave of use cases for the IoT. Simply put, it enables the creation of low-cost location devices that don’t require the batteries to be changed, potentially for up to years at a time. For the IoT, it’s a game changer.