Minimizing the Power Consumption of Location-Based Services on Mobile Phones

Location-based services have to pay careful attention to their power consumption in order not to drain the batteries of mobile phones. It is not a simple task to build low-power location-based services that can run for hours, because such services make heavy use of many power-consuming features of mobile phones. In this article we discuss the power consumption of location-based services and mobile phone features, survey methods for how to minimize power consumption and summarize a number of design considerations for location-based service developers. A successful Location-Based Service (LBS) must not drain the battery of, e.g., a mobile phone. Battery capacity is a scarce resource in mobile phones, because the capacity of batteries is not increasing at the same pace as new power-demanding features are added to mobile phones. If users experience that a specific LBS drains or significantly shortens the battery’s lifetime, they might stop using the service. It is, however, not a simple task to build low-power-consuming LBSs because such services make heavy use of many power-consuming features of mobile phones, such as the screen to display maps, the radio to receive and send data, or a built-in GPS receiver for positioning. Therefore, an LBS has to take great care in how it uses a phone’s features to minimize the power consumption, especially if the service is to run continuously. In this article we dedicate our attention to LBSs on mobile phones, but some LBSs also use other types of battery-powered devices such as positionable tags, where minimal power consumption is also an important issue. So far research on the technical challenges of LBSs has mainly focused on how to improve positioning accuracy and coverage. Only a small amount of research has yet focussed on minimizing power consumption. This article provides an understanding of when it is important to minimize the power consumption of a LBS, how different mobile phone features consume power, and how existing LBSs consume power. Following that, the article gives a survey of methods for the minimization of power consumption and discuss design considerations for LBS developers. I. POWER CONSUMPTION AND LOCATION-BASED SERVICES The importance of an LBS saving power depends on the usage pattern, battery recharge options, and how the service uses the phone’s features. With regards to the usage pattern, an important parameter is how long a service will be running on the phone. The LBSs that are most important to minimize the consumption of are those that are long running for hours or days, however, as will be presented later, the power saving methods for such services are fortunately able to provide the largest savings. The importance of minimizing the power consumption also depends on users’ recharge options, because a service may consume a lot of power if a user is able to recharge the phone when finished using the service. Due to such considerations, it might be situation dependent how important it is for a user that a service consumes minimal power. In regards to the phone feature usage, the consumption impact depends on the power consumption of the individual features. Section II both describes how to profile the power consumption of individual phone features and gives some values for a typical mobile phone. A classification of the power consumption for different types of LBSs are shown in Figure 1. The classified types are inspired by the service types introduced by Bellavista