Ultra-Low Power Host off-load GNSS Positioning

M. Torroja, S. Malkos, C. Verne

Abstract:	Global Navigation Satellite System (GNSS) can continually run in a cell phone with less than 2mA impact on a daily battery life, but architectural changes are needed. In the last few years, there has been an increase on host-based (GNSS) solutions. Host-based GNSS needs less hardware at the GNSS IC level and the host application processor is responsible for the heavy CPU computations. This strategy has many advantages, such as: frequent updates and use of shared memory and code resources of the application processor. This reduces the cost of the dedicated GNSS hardware. All this was done assuming the power consumption of the application processor was shared with many applications such as the operating system itself, services running in the background, navigation applications. However, when we only want to compute a GNSS position and we don’t need any application running in the applications processor, the host based architecture has some limitations with regards to power consumption. This paper explains some of the technologies used to compute a GNSS position with ultra-low power, in other words, how to compute host off-load positions in a dedicated GNSS IC with very limited resources. Two applications that benefit from host off-load are discussed: Geofencing and Position Batching. Geofencing is the application that allows sending reports or triggering alarms in case a predefined area is crossed. Position Batching is the application that stores a position’s history in the IC’s internal memory. Both applications run for long periods of time, and their main task is to compute fixes without the need of other applications. An ultra-low power GNSS position solution or always-on positioning solution is desirable for these scenarios. Regular GNSS (host-based GNSS) position fixes versus those computed with reduced resources (host off-load GNSS) will be compared, as well as the power consumption between host-based GNSS and host off-load GNSS. Different implementations in actual phone Operating Systems, as well as the latest control plane standards for Geofencing will be presented. We will review the minimum requirements for a platform to support host off-load GNSS positioning (software and hardware layers), and propose Operating Systems improvements with defined interface standards in order to fully support host off-load. Finally, Different host off-load technologies for Geofence, such as, Wi-Fi or Cell-ID will be compared.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	2284 - 2291
Cite this article:	Torroja, M., Malkos, S., Verne, C., "Ultra-Low Power Host off-load GNSS Positioning," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 2284-2291.
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