Startup Finds Ways to Cut Mobile Power in Half Without Losing Signal

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Some areas of power consumption have been and continue to be areas of intense scrutiny by the tech industry in attempt to improve power efficiency. CPUs, power supplies, memory, storage, screens and GPUs have been the subject of intense focus for several generations as their respective vendors try to reduce power draw.

And then there’s the base station for a cellular tower. How often do those towers get any power efficiency attention? According to MIT researchers profiled in an article by MIT Technology Review, none. The cost to power cellular base stations worldwide will cost $36 billion this year and consume nearly 1 percent of all global electricity production.

However, there has been next to no efficiency brought to bear on the power amplifier, a device that converts electricity into radio signals. Every cellular tower has a power amplifier and — more importantly for consumers — most notebooks and every smartphone also has a power amplifier that converts electricity to signal.

Power amplifiers consume power in two basic modes: standby mode, which is obvious by its name, and output signal mode, which is when it sends out pulses of data. Dropping into low power standby mode is exactly the method used by phones and laptops to save power.

The problem is that if the amplifier suddenly jumps from a low power state to high power output signal mode, the signal gets distorted. So the solution has been to keep standby power levels high instead of letting them drop into low power mode.

Smartphones compound the problem because they run the power up to output signal mode when doing a 3G data transfer. So the phone thinks it’s talking when all you are doing is watching a YouTube video. The amplifier is busy because the device continually sends out messages confirming the receipt of packets or informing the network when packets are missing.

Enter Eta Devices, a start-up formed by a pair of MIT electrical engineering professors, Joel Dawson and David Perreault. The company is working a new amplifier design that is essentially an electronic gearbox for the cellular tower that cycles through different voltages up to 20 million times per second, selecting the most appropriate voltage.

Dawson and Perreault could not be reached for comment, but it’s reported in MIT Technology Review that the technology is currently still in the labs, with hopes to show it off at the 2013 Mobile World Congress in February. Eta will target LTE base stations first and eventually target the chips in phones, which could double the battery life of smartphones and other mobile devices that connect via 3G and 4G.

“We’re seeing the same kind of innovative power management applied to cellular base stations as what was done in the laptop market over the past 10 years,” said Gerry Purdy, principal analyst with MobileTrax. “All operators realize that they need to reduce the amount of power used to transmit calls and data to phones, particularly smartphones that consume more tower signal capacity, by putting the transmitters in standby mode that can quickly be used when needed.”

Purdy said that in the past, operators simply set up antennas and then powered them to broadcast without minding the electricity consumed by the tower.  “There wasn’t any worry since the power wasn?t that much and demand low. Now, everything matters so there’s more attention to it,” he said.




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