Curing the 802.11a Battery Blues

As an increasing number of handheld computers/PDAs and cell phones adopt Wi-Fi so users can continue roaming, the question arises of how mobile devices can stay connected to wireless local area networks without draining their limited internal power supplies. Two Canadian companies are racing to get the most performance from limited battery-charged devices.

IceFyre Semiconductor, the year-old fabless chip designer, says on average Wi-Fi takes 10 percent of a laptop’s battery and even more from a PDA’s batteries. However, the Ottawa, Ontario, Canada startup claims it has an 802.11a chipset design requiring less than 75 percent of the power needed by competitors.

Julia Ukrintz, a spokeswoman for IceFyre, told 802.11 Planet that PDA manufacturers have already expressed interest in the company’s design. She says the chipset will be available before the end of 2002.

While some power-savings can be found through adjusting the frequency when 802.11 devices search for a connection, IceFyre’s solution both improves the efficiency of existing Orthogonal Frequency-Division Multiplexing (OFDM) modems while reducing components and cost.

OFDM’s inefficient design can be traced back to it requiring devices be able to handle the high peak power, rather than average peak power. Imagine your auto’s performance gauged not by how it operates while idling or driving to the corner grocery, but running flat-out down the highway. Such an inefficient measuring stick meant a chip that should be 70 percent efficient really reached only 10-20 percent efficiency. That low efficiency translates into enormous power demands.

IceFyre took that basic OFDM design and added three Digital Signal Processing-like engines which split the OFDM signal into chunks the power amplifier can digest. After being amplified, the signals are then reassembled and broadcast as a normal OFDM transmission. The result reduces the peak power ratio from 14 dB to 0 dB all within the chipset. By tackling the power efficiency problem of OFDM, IceFyre boosts the efficiency and reduces power consumption.

The company claims its new design will cut battery life for laptops by only 30 minutes. Traditional 802.11 solutions drain as much as two hours from a four hour laptop battery.

By cutting the need for components, such as the baseband filters, SAW filters and low noise filters, IceFyre claims manufacturers could see a 30 percent savings on needed material.

IceFyre isn’t the only Ottawa-based company looking for ways to get Wi-Fi on PDAs. Atsana Semiconductor (formerly Lumic Electronics) in April announced a new way for PDAs and other mobile devices to view streaming multimedia over 802.11 connections.

Where traditional ways of encoding graphics created cell phones and PDA literally too hot to handle, Atsana introduced its design employing thousands of one-bit single instruction multiple data (SIMD) processors operating as a massively parallel array. Atsana’s combination hardware and software solution would allow 15 times the processing power while cutting the power drain on wireless devices. A final reference design is scheduled for release later in 2002, according to the company.

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