by R. K. Bloom

Bluetooth v 2.0/EDR – good old unmade

Bluetooth v 2.0/EDR – good old unmade

The standard of the new millennium

C since its inception and until recent years the Bluetooth standard ahead of its time. The creator of Bluetooth, the company Ericsson, began his research in the field of wireless interfaces for mobile phones in the early nineties. In 1998, Ericsson, jointly with IBM, Intel, Nokia and Toshiba, has released the first specification of the standard Bluetooth 1.0. First of all, the new standard was intended to replace the interface cable cell phones.

Interestingly, in those years, not all cell phone users to understand, why do we need a data cable. There were only two classes of devices, which could be connected to a cell phone. First of all, there were a headset “hands-free” system, and a speakerphone, which required a two-way transmission of monophonic audio quality of the average distance of several meters.

In addition, there were personal computers, interact with your phone as an electronic organizer or as an external modem. This new standard was to provide a replacement wireless serial port (RS-232).

When such problems on the Bluetooth standard is not required either data rate or a large network functionality, or a large radius of action. Designed for mobile devices, the standard was to ensure low power consumption, and in addition, to successfully compete with cable connections, he should be very cheap to implement.

Creators of Bluetooth is often accused of too slow withdrawal of their creations to the market of digital devices. Really strange that officially published in 1998 Bluetooth specification is widely used only in the beginning of the third millennium. However, the reasons for this delay should be sought not in the slow development standard, and a lag in the market itself. In those years, for the Bluetooth just does not have enough problems.

Nevertheless, the founders of the standard pretty quickly appreciated the potential of his creation. Already in 1999 they have demonstrated their desire to continue his improvement. So a group of Bluetooth SIG (Special Interest Group). Along with the five founders of the group included a lot of companies, which included Palm, Microsoft, Motorola, Handspring, Qualcomm and Lucent.

The idea of ??Bluetooth quickly transformed. The new interface is no longer regarded as a trivial replacement of cables cellular phones. He started to turn into a universal wireless interface for personal networks, which could include almost any device. Periodically, a standard were sought flaws that prevent embody a new concept, which served as an occasion for the release of new versions of the specification with relatively small changes and additions. So there were 1.1 and 1.2, which even today have no competition among radio interfaces for personal area networks.

Why is “2.0/EDR”?

Began in 2001 and 2002, widespread support for Bluetooth devices has shown that this, the best standard in its field, still not good enough. Well, actually, the developers were working Bluetooth 1.x relying less on the practical details as to the distant forecasts (by the standards of the digital industry) of the future, and to provide for all of them just could not.

In 2002, Bluetooth was standardized in IEEE (Institute of Electrical and Electronics Engineers), how 802.15.1 standard. That same year, representatives of Ericsson unveiled plans for a new version of the standard – 2.0. It was noted that a new specification is to wait until the end of 2004, when the market before it dorastet.

In November 2004, the Bluetooth SIG has released the specification of Bluetooth 2.0 + EDR (Enhanced Data Rate).

At this time there was virtually no delay in the emergence of devices that support the new standard. Company Broadcom, CSR, and RF Micro Devices have made testing of the prototype 2.0 + EDR and almost immediately began mass production of chips. However, the rapid displacement version 1.x of the market has not begun.

The first device that supports Bluetooth 2.0 + EDR was not a phone, as might be expected, but the laptop from Apple. Bluetooth SIG expects the transition ubiquitous mobile phones to support the new standard is not until next year. At the same time, handset manufacturers expect much more difficult than it was during the transition from version 1.1 to 1.2.

There is a natural question as to why bother making a new standard, if it does not need anyone, and his predecessor is still out of competition all the same because of the cheapness and frugality of energy. Based on what the developers hope to close the growing popularity of version 2.0?

Such grounds as much as two, who grew up demands for speed and convenience of personal networks and the desire of developers to use standard, not only in personal networks.

Members of personal networks want to quickly send large files with video, audio and photo content that they want to seamlessly use the wireless connection to different devices at the same time, they want to listen to stereo high quality audio through wireless headphones and a number of such problems is growing. One of the most frightening examples – the latest printer that can overtake the Bluetooth-enabled devices from which data is sent to the printer. Continued growth of Bluetooth-enabled devices can not cause increase in the size of personal networks where all devices can be operated simultaneously, disturbing each other. Bluetooth 1.x is not ready to serve the needs of such networks, which is especially unfortunate in connection with the approach of competing communication standard – UWB. If the Bluetooth SIG wants to continue to provide standard, ahead of his time, then she needs something better than 1.x.

Also, do not forget that the standard Bluetooth 1.x is already widely used not only for personal area networks, but also for many other tasks, such as multi-user local area networks and sensor applications. In these areas, with Bluetooth 1.x increasingly difficult to compete with other wireless standards such as Wi-Fi and Zigbee.

In such circumstances, Bluetooth SIG could either give the future market to competitors, or to create entirely new standard with specific emphasis on increasing the speed.

New in Bluetooth 2.0/EDR

A brief look at the innovations that allow developers to rely on the growing popularity of the new standard:

Enhanced Data Rate (EDR)

Interest rate data creates many difficulties for developers Bluetooth. On the one hand, there are many problems that at all times sufficient speed 721 kbit / s, which provide the version 1.x and on the other – there is a multimedia tasks that require the transfer of all the large amounts of data.

Speed ??of 2.1 Mbit / s provided by the new version of Bluetooth, still does not even noticeable to the slowest wireless networks, but for typical multimedia tasks it nearly enough.

Once promised in 2002 12 Mbit / s figure 2.1 is more than modest. However, keep in mind that the Bluetooth SIG, developers have been very limited requirements for power consumption and cost, which has been and remains a high priority for this standard.

The Bluetooth 1.x, use one of the most primitive modulation schemes – GFSK (Gaussian Frequency Shift Keying), which was very easy to appeal to developers in 1998, when even the speed of 721 kbit / s seemed redundant. In the Bluetooth 2.0/EDR used several alternative modulation schemes, through which the data rate increases almost threefold. In this case, GFSK is still supported for compatibility reasons.

The absence of “jumping” frequency channels.

The Bluetooth versions 1.x relationship can be one of the 79 frequency channels. To avoid interference from other devices operating in the same frequency range, changing channels 1600 times per second. This is a fairly simple solution, but also, in 1998, such a protocol could be considered as a good communication hardware protection from intruders.

By the unpleasant features of this mechanism are slower communication and difficulties in further improving the standard.

In the version of Bluetooth 2.0 for protection against harmful interference is used in more modern mechanism that allows better use of the standard.

Support for Multi-cast

In personal networks often need to transfer the same data to multiple devices at one and the same time. Bluetooth 1.x provided for the transfer of multiple data queue for each device. At one point in a separate Bluetooth-network could be only one transmitter and one receiver.

It is very difficult to work in real-time tasks such as listening to the joint of the same audio to multiple Bluetooth-headset, or a computer game with a few members that synchronize via Bluetooth. In addition, it is simply slow down, as each time it is necessary to re-establish communication with another device that takes an appreciable time.

In Bluetooth 2.0 provides for the possibility of simultaneous multiple devices to send the same data. This feature is called “Multi-cast”, it has become possible due to the elimination mechanism for rapid changes of frequency channels.

The system QoS (quality of service)

When using the Bluetooth interface to connect to multiple devices at the same time often have undesirable delays. They could have been avoided if the data streams have been better organized.

Bluetooth 2.0 specification provides a special mechanism for QoS (quality of service), which ensures interoperability of devices with a minimum of delay. Devices that support QoS, communicates with each other to coordinate their needs for the immediate transfer of data and painlessly as possible to cope with delayed communication. Thus, without increasing the actual speed of data transmission, it is possible to eliminate the effect of braking, which is so annoying users.

Distributed control of media access

Network model in earlier versions of Bluetooth is very simple. The network has one main and one to seven slave devices. Data can only be transferred between the main (“master”) and subordinate (“slave”) units. In this case, the master device controls the access device to the medium. If the main unit for any reason leaves the network, the rest of the network will not function.

In Bluetooth 2.0, a new protocol that provides distributed control of media access, data transmission, eliminating the network from its dependence on a single device. As soon as the master device leaves the network, its functions are transferred to another device.

In addition, the Bluetooth 2.0 the maximum size of the network increased from 8 to 256 devices. In versions 1.x to increase the network envisaged a rather awkward mechanism to combine simple Bluetooth-networks (“piconet”) into one large network (“scatternet”). In this case, the same device was mainly in one simple network and subordinate to the other. In version 2.0, everything is much easier – from one to 255 slave devices connected to the main one.

Increased energy efficiency

The increased speed of data transmission in Bluetooth 2.0 has led to an increase in consumption of power devices. However, power consumption is not increased as much as speed, so the total energy consumption to transfer the same amount of data considerably reduced. For most purposes, there is more than double the gain in energy conservation.

A more intelligent organization of data and also contributed to the energy in the direction of its contraction. For example, the use of simultaneous transmission of data to multiple devices much more economical than sending the data to each device separately.

Backward compatibility with previous versions

Bluetooth specification version 2.0 provides full compatibility with all previous versions. Device that supports the new standard can communicate with devices for all versions, even if they are combined into a single network. At the same time, new devices will communicate to go at high speed 2.1 Mbit / s, and the old – in the past 721 kbit / s.

The Future of Bluetooth

The new version of the Bluetooth specification can not be considered definitive. Gone are the years when this standard may not develop for a long time, remaining above the current market requirements. Now he needs regular updates to meet time.

Bluetooth SIG plans to release updated specifications annually and promises to provide yet another version in late 2005. Of course, not every new version will contain many new features, like version 2.0/EDR.

Interestingly, the data transfer speed is no longer claimed by developers as a standard in the nearest point of application of their efforts. Much more attention is paid to their plans to improve the capabilities of Bluetooth to a better use of the available speed, for example, in 2005 it is planned to finalize the system QoS, which can be improved almost indefinitely, and in 2006 expected completion of Multi-Cast.

It is only natural that competing standards such as Bluetooth crowding into new areas for him, as expected in a typical personal area networks, forcing developers to continue to improve the strengths of the standard – low energy consumption. SIG intends in 2005 to provide solutions leading to an unprecedented decline in energy consumption.

In addition, new applications Bluetooth, which is becoming more and more, impose more stringent requirements for data security, and, it is difficult even to formulate, not knowing exactly where the new standard will apply. While the direction of the security efforts will focus on in each new version of the specification standard.

Bluetooth and all-all-all

It is clear that new opportunities will enable Bluetooth 2.0 in the near future to enter into active competition with some of the existing wireless standards. It is also expected and the emergence of new standards that could make a serious competitor to Bluetooth.

Consider the balance of power between Bluetooth and its main competitors:

Bluetooth vs. UWB

The new wireless standard called Wireless USB, is almost exactly the same problems as Bluetooth, that is – for the personal networks. The main weakness of the new standard is that it is not ready yet, but its release is planned for the relatively near future, and even then there is nothing to prevent flare-called rivalry between Bluetooth and Wireless USB, which will be on the side of the first low cost and power consumption, and on the side of the second – data rate, under ideal conditions of communication reaching 480 Mbit / s (as USB 2.0). Many existing compliant devices are unlikely to be applied in the proposed Bluetooth struggle, as in fact, Wireless USB will be different from sverhprivychnogo USB 2.0 cable, and only the lack of adaptation of the new standard will be quick and painless.

Instant win one of the standards in the near future, a completely unrealistic. While there are devices that speed is not critical, but it is important to lower power consumption, or vice versa, both standards will be needed. At the same time, we should not expect a rapid division of the world of devices for personal area networks into two incompatible camps, as the devices are quite common, and equally interested in both speed and power efficiency.

It is quite likely race in which Bluetooth developers will build up speed, and developers Wireless USB – to reduce power consumption. Both standards are technically have much in common, so in addition to winning one of them can be considered a variant on the basis of this new standard.

In any case, the final decision – it is not the most the next few years.

Bluetooth vs. Wi-Fi

Theoretically, the standard Bluetooth and Wi-Fi designed for a fundamentally different tasks, but the development of mobile communications and local area networks to meet each other gave rise to the areas where these standards are competing successfully.

First of all, its a small network of mobile devices that are intended, such as gaming and multimedia tasks. The speed of communication and the distance at which the connection is possible in such networks are secondary in relation to the economical expenditure of battery power.

In fact, the speed increase, which takes place in the latest version of Bluetooth, allows him to completely replace Wi-Fi from the field of mobile networks, where he had just begun to emerge. In those areas where Wi-Fi will remain competitive, it will help out not primarily velocity, and specific “sharpened” under complicated networking tasks, and especially for the Internet.

Rather, smart phones and game consoles of the future will use Wi-Fi to communicate with ordinary non-mobile networks and the Internet, and Bluetooth – to connect with each other. With dreams of a single network standard will have to wait again.

Bluetooth vs. Zigbee

The area of ??sensory systems – is the only area where Bluetooth is not just saving falls short of the ideal, and can not withstand even the most minimal requirements.