Enabling Mobility with Clever Power Plays

Carl Weinschenk

One of the basic dynamics of the age of mobility is the tradeoff between what people want the devices to do, how long they want them to perform those tasks and the power available. The question is vital for both smartphones (with room for only small batteries) and larger devices (with larger batteries but more voracious demands).

A number of strategies and tactics are involved in letting users have their electronic cake and eat it, too. One is to increase the power available, either through better lithium ion batteries or alternate power sources, such as direct methanol fuel cells. A second is to tweak devices so that the same services can be performed with less power expenditure. The third is to cut the demand of the services themselves.

The good news is that progress is being made. This week, for instance, location data provider Skyhook said that its new Always-On feature, which is part of its version 4.6, can receive location data as frequently as twice per minute and with 10 to 20 meter accuracy without impacting battery life, according to GigaOm. The story says that the company would not release details on how its system works.

Tackling complex technical problems — and making money doing so — is a hallmark of the industry, and the power issue is no different. At EE Times, Anders Guldahl from Energy Micro offers a very complex look at the situation. Guldahl writes that the microcontroller unit (MCU) is one of the key elements of energy use. Minimization of active energy consumption and use of sleep and deep-sleep modes are two keys to the power issue. The third — and the one on which his paper concentrates — is the process by which the sleep modes are interrupted to perform necessary tasks. Today, he writes, the MCU periodically wakes up to do what is necessary. His idea focuses on tweaking that process:

A better, more energy-efficient approach is to choose an MCU that has a more autonomous system of peripherals and sensor inputs: in this way the CPU does not have to be woken for every measurement.

Guldhahl essentially suggests this: Suppose you run a company. Instead of waking up every five hours to call all the managers to make sure that things are going well, Guldahl suggests that he or she delegate responsibility — and settle in for good night’s sleep.

TechEYE also offers an interesting post on the deep internal workings of devices and how they impact power consumption. The report focuses on research at the École Polytechnique Fédérale de Lausanne in Switzerland. Essentially, researchers did simulations on chips that were less than grade A. They found that some could run applications well enough at lower power than perfect chips. The eventual idea could be to throw out those that completely fail — grade C chips, for lack of a better label — and use grade B. In this landscape, grade A chips are seen as overkill, while the also-rans work fine:

Chips could use the ability to function with a reduced power supply, albeit with a slowed ability to perform certain functions, but the chips would still be able maintain overall abilities while taking less drain on the battery.

Such approaches may bear fruit in the future. In the meantime, there are significant steps that users can take to stretch the time between battery recharges. The Globe and Mail has a list: turn off/turn down the screen and cut to bare minimum use of Bluetooth, Wi-Fi, GPS and other apps and notifications.

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