BY AXXO

DOBRY RANO readers (A hello in Czechoslovakian I learnt from a friend, Anzil). I shall continue from where I left off last week on Bluetooth. It may sound like I’m going on forever on this subject, but it’s intriguing nonetheless.

Requirements. A mobile phone that is Bluetooth enabled is able to pair with many devices. To ensure the broadest support of feature functionality together with legacy device support, the Open Mobile Terminal Platform (OMTP) forum has recently published a recommendations paper, entitled “Bluetooth Local Connectivity”.

This publication recommends two classes, basic and advanced, with requirements that cover imaging, printing, stereo audio and in-car usage.

Specifications and features. The Bluetooth specification was developed in 1994 by Jaap Haartsen and Sven Mattisson, who were working for Ericsson Mobile Platforms in Lund, Sweden. The specification is based on frequency-hopping spread spectrum technology.

The specifications were formalised by the Bluetooth Special Interest Group (SIG). The SIG was formally announced on May 20, 1998. Today, it has a membership of over 11,000 companies worldwide. It was established by Ericsson, IBM, Intel, Toshiba and Nokia, and later joined by many other companies.

Bluetooth 1.0 and 1.0B. Versions 1.0 and 1.0B had many problems and manufacturers had difficulty making their products interoperable. Versions 1.0 and 1.0B also included mandatory Bluetooth hardware device address transmission in the connecting process (rendering anonymity impossible at the protocol level), which was a major setback for certain services planned for use in Bluetooth environments.

Bluetooth 1.1. Many errors found in the 1.0B specifications were fixed.

Bluetooth 1.2. This version was backward compatible with 1.1 and the major enhancements include:
• Faster Connection and Discovery
• AFH (Adaptive frequency-hopping spread spectrum) technology, which improved resistance to disturbances.
• Higher transmission speeds in practice, up to 721 kbit/s, than in 1.1.
• Extended Synchronous Connections (eSCO), which improve voice quality of audio links by allowing retransmissions of corrupted packets.

Bluetooth 2.0. This version of the Bluetooth specification was released on November 10, 2004. It is backward compatible with the previous version 1.2. The main difference is the introduction of an Enhanced Data Rate (EDR) for faster data transfer. The nominal rate of EDR is about 3 megabits per second, although the practical data transfer rate is 2.1 megabits per second. The additional throughput is obtained by using a different radio technology for transmission of the data.

According to the 2.0 specification, EDR provides the following benefits:
• Three times faster transmission speed - up to 10 times (2.1 Mbit/s) in some cases.
• Reduced complexity of multiple simultaneous connections due to additional bandwidth.
• Lower power consumption.

The Bluetooth Special Interest Group (SIG) published the specification as “Bluetooth 2.0 + EDR” which implies that EDR is an optional feature. Aside from EDR, there are other minor improvements to the 2.0 specification.

Products may claim compliance to “Bluetooth 2.0″ without supporting the higher data rate, namely EDR. At least one commercial device, the HTC TyTN Pocket PC phone, states “Bluetooth 2.0 without EDR” on its data sheet. So dear friends, be careful.

Bluetooth 2.1. Bluetooth v 2.1 is fully backward compatible with 1.2 and was adopted by the Bluetooth SIG on July 26, 2007. This specification includes the following features:
• Extended Inquiry Response (EIR): provides more information during the inquiry procedure to allow better filtering of devices before connection. This information may include the name of the device, a list of services the device supports, the transmission power level used for inquiry responses and manufacturer defined data.

• Sniff Subrating: reduces the power consumption when devices are in the sniff low-power mode (This low power mode achieves power savings). Human interface devices (HID) are expected to benefit the most, with mouse and keyboard devices increasing their battery life by a factor of 3 to 10. It lets devices decide how long they will wait before sending keep alive messages to one another. Previous Bluetooth implementations featured keep alive message frequencies of up to several times per second. In contrast, the 2.1 specification allows pairs of devices to negotiate this value between them to as infrequently as once every five or ten seconds.

• Encryption Pause Resume (EPR): It enables secure data transfer by ensuring that no unencrypted data seeps through while the encryption key is being refreshed.

• Secure Simple Pairing (SSP): radically improves the pairing experience for Bluetooth devices, while increasing the use and strength of security. It is expected that this feature will significantly increase the use of Bluetooth.

• Near Field Communica tion (NFC) cooperation: Automatic creation of secure Bluetooth connections when NFC radio interface is also available. This functionality is part of the Secure Simple Pairing where NFC is one way of exchanging pairing information. For example, a headset should be paired with a Bluetooth 2.1 phone including NFC just by bringing the two devices close to each other (a few centimetres). Another example is automatic uploading of photos from a mobile phone or camera to a digital picture frame just by bringing the phone or camera close to the frame.

Bluetooth 3.0. The 3.0 specification was adopted by the Bluetooth SIG on April 21, 2009 (Hey, that’s just 67 days ago). Its main new feature is AMP (Alternate MAC/PHY), the addition of 802.11 as a high speed transport. Two technologies had been anticipated for AMP: 802.11 and UWB (Ultra-Wideband), but UWB is missing from the specification.

• Alternate MAC PHY: enables the use of alternative MAC and PHY’s for transporting Bluetooth profile data. The Bluetooth Radio is still used for device discovery, initial connection and profile configuration, however when lots of data needs to be sent, the high speed alternate MAC PHY (802.11, typically associated with Wi-Fi) will be used to transport the data. This means that the proven low power connection models of Bluetooth are used when the system is idle, and the low power per bit radios are used when lots of data needs to be sent.

• Unicast Connectionless Data: permits service data to be sent without establishing an explicit L2CAP (Logical Link Control and Adaptation Protocol) channel. It is intended for use by applications that require low latency between user action and reconnection/transmission of data. This is only appropriate for small amounts of data.

• Read Encryption Key Size: introduces a standard HCI (Human-computer interaction) command for a Bluetooth host to query the encryption key size on an encrypted ACL (Access Control List) link. The encryption key size used on a link is required for the SIM Access Profile, so generally Bluetooth controllers provided this feature in a proprietary manner. Now the information is available over the standard HCI interface.

LOW ENERGY

ON April 20, 2009, Bluetooth SIG presented the new Bluetooth low energy as an entirely additional protocol stack, compatible with other existing Bluetooth protocol stacks. The preceding naming as ‘Wibree’ and ‘Bluetooth ULP’ (Ultra Low Power) has been outdated by the final naming as ‘Bluetooth low energy’.

On June 12, 2007, Nokia and Bluetooth SIG announced that Wibree will be part of the Bluetooth specification, as an ultra-low power Bluetooth technology.

Expected use cases include watches displaying Caller ID information, sports sensors monitoring the wearer’s heart rate during exercise and medical devices. The edical Devices Working Group is also creating a medical devices profile and associated protocols to enable this market. Bluetooth low energy technology is designed for devices to have a battery life of up to one year.

FUTURE

Broadcast Channel: enables Bluetooth information points. This will drive the adoption of Bluetooth into mobile phones and enable advertising models based around users pulling information from the information points, and not based around the object push model that is used in a limited way today.

Topology Management: enables the automatic configuration of the piconet topologies especially in scatternet situations that are becoming more common today. This should all be invisible to the users of the technology, while also making the technology just work.

QoS (Quality of Service) improvements: enable audio and video data to be transmitted at a higher quality, especially when best effort traffic is being transmitted in the same piconet.

Bluetooth as a technology is revolutionising the way communication is happening. Technology, like someone’s life, is ever changing, but yes, unlike a mortal, it’s never ending.

I still have more to write about it, so till next week… Zbogom.