Bluetooth 1

By Jason Brooks  |  Posted 2004-07-12 Print this article Print

.2"> Bluetooth 1.2

one of the more compelling improvements in Bluetooth 1.2 is the provision for better coexistence between Bluetooth and the other emitters in the swath of unlicensed spectrum in which Bluetooth operates. Version 1.2 makes this happen via a feature called AFH (Adaptive Frequency Hopping).

Bluetooth was designed to deal with interference from its neighbors in the 2.4GHz spectrum—among them 802.11b and 802.11g radios, microwave ovens, and certain cordless phones and baby monitors—by randomly hopping among 79 channels in the band to transmit data. Bluetooth packets lost due to interference from other devices in the band (most of which, including Wi-Fi radios, do not channel-hop) are retransmitted.


  • AFH: Starting with Version 1.2, Bluetooth radios can set their channel-hopping patterns to avoid channels in use by other devices in the 2.4GHz band, such as 802.11b devices

  • Enhanced Inquiry: Bluetooth 1.2 devices can pair up more quickly and more reliably than those that preceded them

  • eSCO channels improve error correction for voice data, thereby bettering performance of devices such as Bluetooth headsets; work remains, however, before Bluetooth can serve as a conduit for higher-quality audio, such as stereo music

  • Solution: Deploy LBS software to provide electronic access to documents, including engineering schematics and train timetables; use LBS software to create Web-enabled maps for the BART Police Departments intranet, allowing officers to visually analyze key information

  • Scatternet support: While present in some current vendor implementations, this key feature, which is required for all but the simplest Bluetooth uses, is not yet part of the Bluetooth specification

    Source: eWEEK reporting
  • AFH improves on this scheme by detecting busy channels and enabling Bluetooth devices to avoid them altogether, thereby improving performance for Bluetooth devices and for their neighbors alike.

    We couldnt confirm whether AFH was enabled in the 1.2 hardware/1.1 software configuration we tested, but certain vendors are shipping AFH-enabled gear. Apple Computer Inc., for one, brought AFH to its Bluetooth implementations two months before Bluetooth 1.2 was finalized.

    The Bluetooth 1.2 specification also provides for shorter connection times between Bluetooth devices through a feature called enhanced inquiry, which cuts in half the maximum time required for devices to pair up, from 10 to 5 seconds. Enhanced inquiry is also supposed to boost the success rate for pairings from approximately 90 to nearly 100 percent.

    Also notable in Bluetooth 1.2 are improvements in sound quality for products such as cell phone headsets through a feature called eSCO (Extended Synchronous Connection-Oriented) channels, which enable the retransmission of corrupted voice data.

    Although the Bluetooth specification has certainly made progress, there are still fundamental pieces of functionality that the standard leaves open to individual vendors to implement as they see fit—a situation that leads to confusion for users and potential incompatibility among devices.

    Scatternets are a great example of this immaturity in the specification.

    The most basic unit of a Bluetooth network is the piconet—a combination of a master device and as many as seven slave devices. The slave devices depend on the master device for handling fundamental chores such as setting the hopping pattern for the piconet, and a slave device cannot have two masters.

    Next Page: Both master and slave.

    As Editor in Chief of eWEEK Labs, Jason Brooks manages the Labs team and is responsible for eWEEK's print edition. Brooks joined eWEEK in 1999, and has covered wireless networking, office productivity suites, mobile devices, Windows, virtualization, and desktops and notebooks. JasonÔÇÖs coverage is currently focused on Linux and Unix operating systems, open-source software and licensing, cloud computing and Software as a Service. Follow Jason on Twitter at jasonbrooks, or reach him by email at

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