Page 74 - DCAP311_DCAP607_WIRELESS_NETWORKS

Wireless Networks

Notes Basic Features

The Bluetooth Special Interest Group (SIG) published the initial version of the specification in
mid-1999. There have been updates since then, but the technical attributes are essentially the
same. Bluetooth transceivers operate at up to 1 Mbps data rate in the 2.4GHz band, using FHSS
technology. It constantly hops over the entire spectrum at a rate of 1,600 hops per second, which
is much faster than the 802.11 version of frequency hopping.
Low-power Bluetooth devices have a range of 30 feet. High-power Bluetooth devices, however,
can reach distances of around 300 feet. The high-power mode, though, is rare.
Bluetooth modules have relatively small form factors. Typical measurements are 10.2 x 14 x 1.6
millimeters, which is small enough to fit in a variety of user devices.
Bluetooth enables automatic connection among Bluetooth devices that fall within range of each
other, but a user has the ability to accept and disallow connections with specific users. Users,
however, should always be aware of whether their Bluetooth connection is enabled. To ensure
security, disable the Bluetooth connection. Encryption is also part of the specification.

Could Bluetooth Replace Wireless LANs?

Bluetooth has characteristics similar to wireless LANs. Through the use of the high-power
version of Bluetooth, manufacturers can develop Bluetooth access points and routers with
a similar range as 802.11 networks. The current Bluetooth products, however, are mostly low
power and focus on wireless PAN functions. In addition, it would be difficult for any Bluetooth
wireless LAN products to gain a strong foothold in the market because 802.11 products already
have widespread adoption.
The place where Bluetooth falls behind 802.11 is performance and range. 802.11 components
can reach data rates of up to 54 Mbps, while Bluetooth lags way behind at around 1 Mbps. This
might be good enough for most cable replacement applications? such as an interface between
headphones and a PDA? but higher performance is necessary when surfing the web through
a broadband connection or participating on a corporate network. Also, the range of 802.11 is
typically 300 feet inside offices, which is much greater than Bluetooth. Bluetooth would require
many access points to fully cover larger areas.
As a result, it’s highly unlikely that Bluetooth products will win over 802.11. This is certainly
apparent because electronics stores primarily sell 802.11 (Wi-Fi) solutions for wireless LAN
applications, not Bluetooth.

Could Wireless LANs Replace Bluetooth?

It’s possible that 802.11 wireless LANs could have a big impact on the sale of Bluetooth devices,
mostly because 802.11 meets or exceeds nearly all of the characteristics of Bluetooth. Because
widespread adoption of Bluetooth is still lacking, there’s time for 802.11 vendors to get their foot
in the door with manufacturers needing support for wireless PANs.
Some modifications would need to be made, however. The size of 802.11 components needs
to be smaller, but that is becoming more of a reality as semiconductor companies strive for
miniaturization of their 802.11 chipsets. These smaller components require less power, making
them more competitive for devices, such as mobile phones, that have smaller batteries. With the
802.15 group defining standards for wireless PANs based on Bluetooth? and the 802.11 group
focusing on wireless LANs? it’s likely that both Bluetooth and 802.11 will continue to coexist and
complement each other.

Minimizing Bluetooth Interference
As more wireless products become available, you need to carefully manage potential frequency
interference. Tests have shown significant interference between Bluetooth and other systems

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