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Complementary Wireless Technologies

The preceding sections highlighted several differences between WLAN and WPAN technologies, namely IEEE 802.11 and Bluetooth technologies. Those differences include the following:

  • Range: The reach of IEEE 802.11 is about 10 times that of Bluetooth technology.

  • Raw data rate: The data rate for Bluetooth communications is about one-tenth that of IEEE 802.11.

  • Power consumption: The trade-off of power consumption versus range and data rate results in significantly lower consumption for Bluetooth devices

  • Packet technology: Bluetooth links natively carry both voice and data using packets designed specifically for Bluetooth transports, whereas IEEE 802.11 heavily leverages Internet technologies for "Ethernet-style" data networking.

Let's face it: Bluetooth wireless communication is optimized by design for WPANs and IEEE 802.11 is optimized by design for WLANs. With these differences, it seems puzzling that the two technologies would be perceived as competing with each other. Each has strengths that make it well-suited to its primary domain, and that are, in turn, weaknesses in the other's domain. For example, there would be little need in a WPAN for transmission power capable of reaching a device 100 meters away, and the associated power consumption to do so would be a drawback to using IEEE 802.11 for a WPAN. In fact, we view the two technologies as complementary to each other, a view also expressed by Ericsson.

So, then, why are these technologies so often positioned as being in a battle against each other? Here are three theories as to why the perception may exist:

Both operate in the 2.4GHz spectrum, and thus inevitably interfere with each other when used in the same place at the same time.

There is some potential overlap in a few usage models between the two technologies, with each having some capabilities to do some of the things that the other does, albeit non-optimally.

They are developed by different industry groups, so they must be at odds with each other.

With regard to the 2.4GHz spectrum, it is unlicensed virtually worldwide. Hence, it is an attractive band for wireless communication technologies that can operate within the constraints imposed for use of the spectrum. Among the constraints are limits on the transmission power and the measures required to deal with RF interference. IEEE 802.11 and Bluetooth wireless communications both take place in the 2.4GHz band. It might seem this band is overcrowded, so one or more technologies need to "lose" if others are to operate effectively in this spectrum. Not true. A primary consideration for any technology that operates in this band is that it must expect RF interference and implement measures to deal with it. Clearly, IEEE 802.11 and Bluetooth technologies can interfere with each other, but we are aware of no studies that show that either technology fails when subjected to normal (or even extreme) interference from the other. Performance degradation often is an effect of RF interference, and groups within the IEEE and the Bluetooth SIG are performing studies and developing recommendations to understand and address this and other issues related to RF interference. Furthermore, there is some evidence that there is room for several players in the 2.4GHz spectrum. Another unlicensed band, 900MHz, is used by many technologies and devices, such as cordless phones, garage door openers, baby monitors, and others; and no single technology has crowded out the others.

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