Smartphones — known for having a shorter battery life than standard mobile phones — may soon find themselves less reliant on a charger. Once UCSD professors and graduate students are completing a hardware renovation that would improve battery life.

The extra efficiency would come from typically unused transistors called “dark silicon.” Transistors are an integral part of computer chips as they can increase the power of the electrical signals that pass through them.

However, because they produce heat, the number of transistors that can be active in a computer chip is limited.

Several professors and graduate students are developing a prototype mobile application processor called GreenDroid, which would reduce battery usage up to 15 times by reclaiming dark silicon without overheating the hardware.

“GreenDroid is a new mobile application processor that we’re developing for Android smartphones,” computer science graduate student Nathan Goulding said. “The idea is to use specialized hardware to save energy for common applications on Android phones.”

Since their initial integration into the world of computer engineering, the number of transistors that can be placed in a computer chip has risen exponentially, a phenomenon known as Moore’s Law. Although processing speed has enjoyed a few years of rapid growth from this addition, computer engineers have hit a wall. Utilizing all transistors at once is no longer feasible due to insufficient heat dissipation.

“When you buy a new chip, you can only use a tiny percentage of it at once,” Goulding said.

Attempting to use all of the transistors at once causes the chip to heat rapidly and, without sufficient ventilation, cause the hardware to melt.

“We’re running against something called the utilization wall,” Goulding said. “We can no longer use all of the transistors on a chip at once.”

The utilization wall prevents the chip from using too much power and overheating by limiting the amount of transistors being used. Dark silicon is the name for a transistor that remains unused because of the insufficient power available. A number of transistors that aren’t used remain inactive, or “dark,” since it cannot be utilized without changing the chip. However, GreenDroid activates the dark silicon through a special purpose hardware known as conservation cores.

“Conservation cores are specialized pieces of hardware that greatly reduce energy,” Goulding said. “Each core can perform one function, and it does so extremely efficiently.”

GreenDroid is currently specific to the Android platform due to its open-sourced nature, which allows the researchers to test their product at no additional cost. However, other hardware — such as game devices or other smartphones — may be compatible with GreenDroid in the future.

“We’re starting with an Android prototype, but conservation cores can be applied to all sorts of hardware — including general purpose processors, game hardware or other smartphones,” Goulding said.

Preliminary tests estimate the battery life of Android devices to improve by 10 to 15 times their current life when the conservation cores are in place. Not only does battery life improve, but the phone can run more efficiently while maintaining a low temperature by using less processing power.

“We can actually use [dark silicon] for computations, and that’s how we save energy,” Goulding said.

Readers can contact Jerry To at [email protected].