Just recently we published an article on our website regarding the connection between Bluetooth and battery drain. The result was quite surprising. Today we’ll look at whether having location services (GPS) turned on can increase power consumption. If so, when does it happen? We drew information from professional research called “Greener and Smarter Phones for Future Cities: Characterizing the Impact of GPS Signal Strength on Power Consumption”. The complete publication can be found at ResearchGate.
GPS significantly affects battery consumption only in a certain state
When it comes to the consumption of battery power by receiving or sending signals, which includes, but is not limited to GPS, Wi-Fi whether mobile network, several factors must be taken into account. Older devices with outdated software and outdated hardware may have higher consumption. However, the signal intensity probably has the greatest influence. If you use positioning in a place where the signal is weak, such as under the roof of a department store or in bad weather, the consumption will increase.
So what is the power consumption while using GPS? Well, there is practically no simple or precise answer. But we can say that the consumption is quite large. January 2016 study showed that in the case of a strong signal (outdoor test) it is possible to consume 13% of the battery during an hour of continuous GPS use. If the signal is weak (indoor test), consumption will increase significantly. Battery drains up to 21% per hour. Source study is old and new hardware and software can be more efficient.
As a general rule, if you leave GPS on and there’s no app in the foreground that needs it all the time, you won’t notice a difference in battery life. The operating system of a modern device will take care of this for you. On old devices, turning on the GPS icon in some cases meant constant positioning and constant battery drain. Modern software is able to intelligently control when exactly the phone should communicate with satellites in order to make energy consumption more efficient. If you are interested in more details on how the research was conducted, we recommend that you download the PDF from ResearchGate and study the publication yourself, or read our abbreviated search for the given publications below.
Newer study from December 2020 analyzes GPS power consumption on smartphones Xiaomi Mi 8 (dual-frequency GNSS) a Xiaomi Redmi Note 7 (single-frequency GNSS). Concrete results show that dual-frequency GNSS v Xiaomi Mi 8 consumes more power than single-frequency v Redmi Note 7. Power consumption was measured under various conditions using a proprietary application that requested a location update every second.
In short, when actively using location services, a smartphone can consume approx 10-20% battery per hour. It has also been proven that energy consumption in an environment with a poorer signal (interior) is 20-30% higher than in an environment with high-quality coverage, i.e. outdoors, ideally with a clear sky. Factors affecting energy consumption include:
- Type of GNSS chip
- Signal quality
- Location update frequency
- Use of special algorithms to optimize energy consumption
- The specific model of the phone and its software / hardware
Other technologies also assist GPS for accurate location determination
Not only GPS is used to determine the location, but also other satellite systems as well as Wi-Fi, Bluetooth or a mobile data network. All these technologies and systems work together to make positioning as fast and accurate as possible. For determining the location in the city and in places where there are several Wi-Fi networks, determining the location is much more efficient in this way, both in terms of time and energy.
Outside the city, battery usage for positioning can be higher because of the use of terrestrial mobile network transmitters and satellite systems such as GPS. A more specific rate of energy consumption depends on the intensity of the received signal. The stronger the signal, the lower the consumption. Conversely, if the signal is interrupted by, for example, clouds or physical obstacles (e.g. tall buildings), the receiver in the smartphone has to work more intensively in order to capture the signal and subsequently process it.
The key is to have a high intensity signal
The primary factor that affects battery consumption is GPS signal strength, measured as Signal to Noise Ratio (SNR). High SNR (strong signal) results in lower battery consumption, while low SNR (weak signal) causes higher battery consumption.
Experiments in a January 2016 study were conducted on a smartphone LG Nexus 4. Two types of apps were used: a location-based app (LBA) from the Google Play Store and a custom Android app called GPS SNR. Tests included using these apps indoors (with a weaker GPS signal) and outdoors (with a stronger GPS signal). The results of the test with the application from the Google Play Store were as follows:
- Indoor testing (weak signal, SNR < 25): The smartphone’s battery charge dropped by 21% in one hour, which means continuous use would drain the battery in about five hours.
- Outdoor testing (strong signal, SNR ≈ 42): Smartphone battery charge has dropped by 13% over the same period, indicating a reduction in power consumption of up to 38% compared to the interior.
Custom Android application called GPS SNR showed the following impact on battery consumption:
- Tested indoors and outdoors for 30 minutes:
- With a weak indoor signal, the application consumed 7% of the battery.
- With a strong signal outdoors, the application consumed 4% of the battery.
The relationship between signal strength and power consumption is quantified using time to first acquisition (TTFF). Experiments have shown that:
- Longer TTFF (due to weak signals) leads to higher power consumption.
- Stronger signals shorten the TTFF, saving battery.
The mathematical relationship derived from the study is:
E = 0.0797 × TTFF,
where E is the energy consumed and TTFF there is time until the first position is detected. This model emphasizes the direct proportionality between TTFF and energy consumption. As we already mentioned, newer devices can be much more efficient and a more accurate indicator experiment from December 2020, which we also wrote about above. We decided to describe the testing methodology because it can be applied even today and the principle remains approximately the same.
Our own little experiment
On a smartphone Google Pixel 8 Pro we downloaded the app GPS Test. It can determine your geographic location, determine the world time, as well as the time of sunrise and sunset, detect specific GNSS satellites located literally above your head, and also measure the SNR (Signal to Noise Ratio) from specific satellites. We left the application on for an hour indoors with average SNR = 25. Battery charge percentage decreased by 5 %.
Indoor test
Outdoor test
After an hour-long outdoor test with average SNR = 35 the battery ran out o 3 %. The reason for the lower consumption will probably be a more efficient chipset and the optimization of the used application with a lower frequency for updating the location. The screen was active all the time, but we set the brightness to minimum. We also closed applications in the background and turned off other functionalities, such as Wi-Fi and Bluetooth. Only the mobile network was active without an active data connection. Interestingly, an average of 19 satellites were detected indoors by the smartphone, while approximately 45 were observed outdoors. You can also notice a very large deviation depending on the intensity of the received signal. Indoors, the positioning accuracy was approx 43 meterswhile she only moved around outside 2 meters.
The consumption of the GPS receiver is naturally higher
Compared to other components and technologies, GPS is one of the more energy intensive. Specific values vary widely between devices. Other components, such as the chipset and its CPU, Wi-Fi, 5G modem or display, also consume a significant amount of energy, but the constant need to update the location, for example during navigation, makes the GPS receiver particularly demanding.
There are ways to reduce energy consumption by using location services. However, these must be applied either by application developers or by the manufacturers of the hardware itself, and advanced algorithms are applied in modern devices that mitigate their impact on consumption.
Our tip
Source: www.mojandroid.sk
