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Tuesday, September 15, 2009

How Bluetooth, UWB, and 802.11 stack up on power consumption

Today, for example, nearly 2 billion people use mobile phones on a daily basis, for voice services as well as for a growing number of data-centric Internet applications.

By 2013, analysts predict that one in every three mobile phones sold will be a smartphone. Entertainment-based mobile devices are also on the rise with the digital still camera (DSC) household penetration rate expected to reach 80% by 2010 in the United States alone.

Wireless technologies such as Bluetooth, Ultra-wideband (UWB) and WLAN, all make this wireless data transfer viable today, yet each has its own obstacles which makes its use in the mobile market challenging. Additionally, due to the inherent nature of each of these technologies, some may be better suited than others in applications requiring, for example, a high bandwidth or a wide operating range.

In the case of the mobile market, one of the main requirements is long battery life. Therefore, one key factor that must be evaluated when determining which technology to implement in a mobile device design is power consumption.

Throughput is also an important factor as it contributes to the technology's overall power consumption. Choosing the right wireless technology is crucial to developing an optimal, commercially-viable mobile device.

Understanding power consumption

At the end of the trip, the consumer returns home only to find that the camera has a mere 5% of its battery power left, making it impossible to transfer the camera's content to another device, such as a desktop computer.

During typical camera usage, this is exactly the type of capability that today's consumer demands.

Given this scenario, it is easy to see why low power consumption and high throughput are so critical. Standby power and active power consumption (e.g., in a cellular phone the power attributed to talk time, or in this case, attributed to data transfer) must therefore be reduced in order to increase battery life.

Consequently, today's designers require implementation of a wireless technology which supports multiple low power modes, regardless of whether the device's active power is on or it is in standby mode.

Throughput (e.g., power per Mbit of data) also plays a critical role here because even if a protocol's active power is high, it may ultimately exhibit the lowest total power energy consumption, and therefore provide the best power efficiency, if it transfers data extremely fast.

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