Bluetooth Puts Bite on Mobile Communications
A description of the Bluetooth specification, its implementation and application, and some hurdles to overcome
BLUETOOTH PUTS BITE ON MOBILE COMMUNICATIONS
Within a year, devices of all kinds - from laptops and cell phones, to PDAs and household appliances - will be capable of communicating and interoperating with one another using a new wireless networking technology called Bluetooth. Before this happens, however, some hurdles must be jumped.
Living in perpetual terror of Viking invasions and raids, 10th-century monks along the coastlines of the North Sea and the Baltic would pray daily, "From the fury of the Northmen, deliver us, O Lord!" Now there is another Nordic invasion preparing to spread globally, only this time it will be welcomed by those experiencing it. The new raider's name is Bluetooth.
Named after a semi-legendary Norwegian king, Harald Bluetooth (see sidebar, page 114), this open specification seeks to create a single digital wireless protocol to address the need to wirelessly connect PCs and mobile, handheld devices such as smart phones, smart pagers, notebooks, and various digital devices that need to synchronize with one another to keep data content consistent. The specification is designed to operate as a "virtual cable" that might, for example, enable a laptop to use a cell phone to access E-mail or transmit data to a fax machine. Figure 1 shows a typical Bluetooth application scenario ushering in a new era in bad table manners.
Fig. 1 A typical Bluetooth application.
Bluetooth is a specification started by a handful of key promoters. In 1998, Ericsson, Intel, IBM, Puma Technology, Microsoft, Motorola, Nokia, and Toshiba formed a consortium to address the creation of a single digital wireless protocol to address end-user problems arising from the proliferation of various mobile digital devices. The commercial specification, Bluetooth 1.0, was issued last September. These companies hold a special position with the founding Bluetooth Special Interest Group (SIG), where they promote and have priority with the specification's evolution. There are currently some 2000 companies working on or developing products based on this specification, making it the fastest growing industry standard ever. By 2001's end, hundreds of millions of electronic devices are expected to be Bluetooth-enabled.
The first products will be on the market the middle of this year. An Ericsson headset that works with an Ericsson GSM cell phone has been announced, and Nokia has demonstrated a GSM cell phone that talks to a laptop and a digital camera. Some of these are demonstration products because everyone is developing production-quality testing methods for the high-volume fielding of quality products at a low price.
Fig. 2 Bluetooth-enabled products.
Fig. 3 The block diagram of a Bluetooth chip (source: Toshiba America).
The future looks bright for this new market. Cahners' In-Stat Group predicts that in 2003 manufacturers will ship more than 200 million units of Bluetooth-enabled products, as shown in Figure 2. In a report about the technology, it describes as "conservative" its projection that by the end of 2005 this amount will triple, with more than 672 million devices worth nearly $3.2 B being sold. In-Stat is not alone in predicting a rosy future for Bluetooth. Dataquest calculates 250 million devices will be sold by 2002, while Frost & Sullivan estimates $36.7 M in sales this year, and almost $700 M by 2006.
A BLUETOOTH TECHNOLOGY TOUR
Bluetooth enables transparent wireless RF communication between digital devices, offering the triple advantage of a voice/data access point, no cabling and creation of a personal ad-hoc network. It is designed to function even in noisy radio environments, and offers a high transmission rate, while error-correction methods protect data integrity, and encryption and authentication routines ensure privacy.
The generic Bluetooth chip (a block diagram of the chip is shown in Figure 3) is equipped with a transceiver and is designed to be built into digital devices such as cell phones, personal digital assistants (PDA), PCs and laptops. The wireless RF component enables fast and secure voice and data transmissions unhampered by line-of-sight restrictions. Because it operates at the internationally available unlicensed industrial, scientific and medical (ISM) 2.4 GHz frequency band, worldwide compatibility is ensured.
Bluetooth is the first major step to truly personal networking. It operates in a multiple piconet topology that supports point-to-point and point-to-multipoint connections. Currently up to 10 piconets can be established and linked ad hoc, synchronizing together all devices on the same piconet. The full-duplex data rate within a multiple piconet structure with 10 fully loaded, independent piconets is more than 6 Mbps. Bluetooth's baseband technology supports both synchronous connection oriented (SCO) links for voice and asynchronous connectionless (AC) links for packet data.
As the specification stands today (Table 1 lists the major aspects of the Blue tooth specification), Bluetooth supports an asynchronous data channel in asymmetric mode of maximally 721 kbps and 57.6 kbps in the reverse direction. Alternatively, the data channel can be supported in a symmetric mode of maximally 432.6 kbps, up to three simultaneous packet voice channels, or as a channel that simultaneously supports both asynchronous data and synchronous voice. Full duplex communications is supported using time division duplex (TDD) as the access technique. Voice coding is accomplished using the continuously variable slope delta (CVSD) modulation technique. Security is provided through encryption and authentication, using a challenge-response mechanism. Spread-spectrum techniques are used to improve performance in the much-used ISM band.
The RF output portion of the chip is self-regulating, which is one of the reasons why it consumes less than 3 percent of the power used by a mobile phone. If the transmitter senses that a receiver is only a few meters away, it modifies its signal strength to suit the range. When traffic volume is reduced or stops, the radio shifts to a low-power mode that is interrupted by short signals to verify the established connection.
Ken Morley, director of Wireless Personal Engineering at 3Com, Salt Lake City, UT, expects the uptake on Bluetooth will be quicker than other new technologies. "It'll be interesting later on, to see what kinds of products it leads to," he said. There are about 24 companies producing devices - either full sets comprising radio and baseband, or just radio and just baseband. "The rush to get into the market and play in it is largely due to the fact that the technology is made to be produceable inexpensively," added Morley. "The fact there is such a large number of players is a testimonial to objectives being met."
However, the optimism must be tempered somewhat. First products had been expected at the beginning of the calendar year, which meant chips should have been available at the middle of last year. This did not happen and the schedule is running behind. The specification was delayed and there have been some changes now that it is being implemented, and the SIGs are going through a few iterations of errata. However, the general consensus is that for the most part the specification is solid, and some solid hardware solutions are beginning to appear. The early hardware developers see companies beginning to produce quantities of devices that are going into products. Morley predicts that these products will ramp up during the last half of this year and then, starting in 2001, flood the market.
Normal range (m)
10 (0 dBm)
Optional range (m)
100 (+20 dBm)
Normal transmitting power (dBm)
0 (1 mW)
Optional transmitting power (dBm)
-30 to +20
Receiver sensitivity (dBm)
Frequency band (GHz)
Gross data rate (Mbps)
Maximum data transfer (kbps)
721 + 56/three voice channels
Power consumption (hold/park) (mA)
Power consumption (standby) (mA)
Power consumption (maximum) (mA)
Packet-switching protocol based on a frequency hop scheme of 1600 hops/second
Fig. 4 A combination cell phone and PDA (source: Toshiba).
3Com has not yet announced or pre-announced any Bluetooth products. "Our primary products will be connectivity to notebooks and handhelds, primarily the Palm units. You can expect to see devices that will allow, in one form factor or another, PCs to connect together, to other devices, or possibly the Palm devices to connect together."
THE HUMAN FACTOR
Cell phone manufacturers are approaching Bluetooth cautiously, considering its multiple connectivity options. Once before, they found out the hard way, that producing all-in-one phones can be risky. Customers did not want a PDA and cell phone combination, as shown in Figure 4, because they cannot use both at once. When someone must look something up in the PDA part of the phone, the conversation must be interrupted because the phone must be taken away from the ear to look at the display and work the keys to retrieve information. It is better to split the devices and have them communicate with one another.
For mobile phones, voice is still the killer application. "Initially at least, voice will drive the Bluetooth market," stated Morley. "The wireless headset that communicates with the cell phone is here. Later will come data applications as the technology ramps up in other markets - so first comes the phone, voice, and data. Then integrating it all together so that if I put a data access point that can also handle voice I can roam around the office talking into my headset." In this scenario, the cell phone would become the only phone. Other devices, such the notebook computer and PDA would also do data access through the access point.
Bluetooth use is subject to the device's coverage area. Bluetooth radios have two standards, low and high power. Due to battery considerations, most client devices will work at lower power, with access points probably running at a higher transmit power and sensitivity, possibly improving client device coverage.
Some view Bluetooth as a sort of latter-day enterprise world Trojan Horse. The prediction is that cell phone manufacturers will enable it for wireless headsets, then it will spread to Palm or CE (Conformite Europeene, the European EMC standard) devices for better data management. Then the user will want to use these devices at home just as he does at the office, and install a home individual access point there.
In the beginning, these individual access points may not communicate with all devices. For example, someone might want an access point for the phone and wireless headset. Others might want it for Palm-to-PC types of applications. The territory of what is possible with the technology is being laid out now for areas like public access points, possibly data kiosks or airports, or even hotel rooms or other semi-public venues; however, none of this will become noticeable until sometime in 2002.
Access points will have different capabilities for miscellaneous devices and applications. Presently, Bluetooth does not handle video, but this capability is not necessary for many applications. There will be multiple devices at the cable or digital subscriber line (DSL) end within the home. Right now, Ethernet is in the lead, although there are other options such as HPNA, power line carrier, and wireless LANs. Bluetooth will become one more mode of data distribution within the home and office.
Bluetooth does not present an either-or situation. The choice need not be either wireless LAN or Bluetooth. These have different characteristics and strengths as extensions of the corporate or small business LAN. Obviously, someone needing higher bandwidth, more data, or more extensions may consider 802.11b (or 802.11 High Rate), an 11 Mbps wireless standard designed to provide full network services to a user with a notebook or desktop PC, whereas many Bluetooth-enabled devices will never be 802.11-enabled. Bluetooth will most likely become the primary - or even only - option between, for example, cell phones or PDAs. The limiting factor is power, because it does not appear that the power to do more can be packed into smaller battery-operated devices any time soon.
Perception is a problem for Bluetooth, because some believe it has been overmarketed. It has great strengths and, as a wire-replacement technology for headset-to-phone, phone-to-PDA, or notebook-to-notebook it will do a good job. However, visions of ad hoc networking have been encouraged, in which the user walks down the hall and everyone joins the network and works together. Doubtless, it will come to this, but a considerable evolutionary process must occur first, and until the bugs are worked out, everything will be a bit clumsy.
From a technology standpoint, there are issues not just with Bluetooth, but most of the other technologies working in the same 2.4-GHz band - stadium lights, microwaves, 802.11. They all compete for the same piece of spectrum and there is bound to be some congestion.
Because Bluetooth is a fast hopper with fairly low power, it should survive better than others (such as 802.11) in this environment, at the cost of degraded performance. It is clear, however, that for all these schemes to survive, they must co-exist and interoperate. This is the aim of all the working groups both in the IEEE groups as well as in Bluetooth although. Until niches get sorted out, every scheme will experience some degradation.
Fig. 5 A Bluetooth module prototype (source: Ericsson).
Within range of its access points, Bluetooth is expected to work as well or better than a cell phone, but this, too, has been oversold. Ten meters is bandied about as the top range, but some point out that this is right at the edge. At 10 meters, communication will get problematical, much like in a cell phone low coverage area. If the user's personal reach, say a radius of slightly more than about an arm's length is viewed as the communication capability, there should be no problem.
Once products start coming out in volume, it will become immediately apparent which issues, if any, need sorting out, and the technology will mature. If past history is any indication, there will be a shakeout of players. Their number will get smaller, and the winners will get larger.
The Bluetooth standard was started from a user model. It was driven by an underlying technology model and a user's model at the top. The standard has profiles. A profile is a vertical slice through the protocol stack, a usage model that the standard originators want to ensure works. Profiles establish, for example, how dial-up networking, fax, or wireless headsets for telephony will work, to ensure that the various application pieces will function together.
This work continues in the various working groups. Some of these will result in standards enabling more ad hoc networking. Operation within cars and human input devices are under consideration. This continuing work is not intended to obsolete current specifications, but rather to fix and streamline. It is possible that improvements will be made in the radio, or another band for higher power will be selected for a Bluetooth II version.
This broadening of the specification is to ensure general interoperability for different functions, and does not mean Bluetooth I devices will be outdated any more than an old 9600 kbps fax is obsoleted by its 14,400 kbps cousin. Bluetooth II would be for device classes requiring higher bandwidth but retaining the benefits of Bluetooth. For example, some applications will require higher speed data, enough digital bandwidth to handle high fidelity audio, or even video. Other than that, the low levels, radio, baseband and basics of the specification are pretty much fixed. The work is aimed at defining interoperable and standardized methods of doing things, to avoid having five competing standards, as was the case during the early days of the modem wars, and avoid de facto battles.
THE COST QUESTIONS
Ericsson Microelectronics in Sweden produces the chip/module shown in Figure 5 that will go into the headset the company is introducing this year, as well as mobile phones and other products. As Stefan Lös, a senior product manager at Ericsson puts it, its product is at a sampling, prototype stage. "We're delivering chips and modules to companies that have their own development projects," he said.
When queried about the thorny issue of pricing, Lös was quite straightforward. "Prototype pricing is always high. As soon as the prototype becomes a product and one goes through the learning curve toward high volume, prices drop." Lös admits that much depends on industry expectations. "At present we've defined two products - a radio module and a complete solution. The complete module, which includes radio, baseband, flash memory, all the discrete components, shielding, and basic firmware has an introduction price under $30.00. The radio is under $10.00."
Lös agrees that for the technology to succeed the module cost must drop to $5 or even $3. "Perception is one of the difficulties here," he said. "OEMs compare the price of a module to that of a chip set. This is apples to oranges. With a chip set, the OEM must build the complete solution himself, which means that in the end the cost of integrating the chip set into his system is higher than that of integrating an initially more expensive module."
The Ericsson module is pre-certified and pre-qualified, both for the Bluetooth specification as well as FCC requirements. "You have the certainty that the Bluetooth implementation will not cause you any problems," said Lös, adding that because the module is already assembled and tested, the OEM's implementation costs are kept down. "Were the OEM to do a discrete implementation instead of using a tested module, he'd be subject to yield loss, assembly loss, and testing costs. This is an invisible value and a plus in the consumer market, where time to market is crucial."
The battlefields for the next generation of Bluetooth will be cost, lower power consumption, and real estate. This will require going from a 0.50-mm to a 0.35-mm BiCMOS process, considerably reducing chip power and real estate requirements, leading to lower costs. Presently, Bluetooth modules have too many different passive components. Integration levels must be increased, with more module-level functionality being integrated into the chip.
Toshiba has a large commitment to Bluetooth. "All our sister companies - PCs, cameras, semiconductor companies - have access to the technology and are deeply involved," said Andrew Burt, wireless market director at Toshiba America Electronic Components, Milpitas, CA.
Toshiba sees Bluetooth as a winning market in the wireless LAN area, where many technologies compete for RF connectivity. "The fact that it is an open standard, patent-free, and that a broad industrial base has joined it make it difficult to stop." Burt added that Bluetooth's advantage is that it is targeted as a short connectivity system that does not attempt to compete with wireless Ethernet.
Like others, Toshiba views the price of the Bluetooth solution as a key driver. However, this is a tough objective. For the $5 per module maximum price considered necessary, the company must provide an antenna, an RFIC, a baseband IC and protocol firmware. This is a very challenging target, to say the least.
The approach being taken at the moment is to have an IC built using bipolar technology for the RF portion, and an MOS baseband controller. Early adopters seeking a complete Bluetooth solution want the microcontroller to reside within the module as well. Long-term, however, since most Bluetooth-enabled products already will have a microprocessor - a cell phone or notebook, for example - and the baseband evolution path points to increased power, it seems inevitable that protocol activity will switch over to the host product.
Fig. 6 The MSM3300 device's block diagram.
Like Ericsson, Qualcomm CDMA Technologies Division is developing the ASIC chips and software solutions for mobile CDMA handsets and bay stations. Last February, it announced its MSM3300 chip Bluetooth solution, the first chip to have integrated, on-chip Bluetooth digital processing, with a CDMA modem. Figure 6 shows the chip's block diagram. "The MSM3300 will interface to RF chips supporting Bluetooth," explained Luis Pineda, vice president of the product management group at Qualcomm. "We're developing a solution that interfaces to a number of RF suppliers' products. We've a partnership with Ericsson Microelectronics whereby our chip directly interfaces to their Bluetooth RF component."
Qualcomm brings digital processing on-chip, providing a substantial cost and power savings, as well as requiring less PC board real estate because everything, including the software, is integrated. It has developed a protocol stack for Bluetooth and embedded it with CDMA software and is already shipping production volumes using 0.25-mm CMOS. Qualcomm is designing its future products based on 0.18-mm CMOS.
Like others, Pineda does not see problems in mainstreaming Bluetooth. "No new technology is needed. Compared to working with CDMA, it's easy. Bluetooth is an open standard, it's a technology that doesn't present barriers to the development of different solutions to bring products to market." However, testing for compatibility is a problem. A company may produce chips that will go into a cell phone, but unless it builds computers or partners with someone who does, there is no way to certify that the solution works. Eventually, as more products are developed and certification groups develop, this will cease being a problem.
MARKET FOR EXISTING DEVICES
For the first couple of generations, Bluetooth will be an evolving market. Initially, OEMs are looking for fully tested Bluetooth-compliant products - antenna, RF, baseband on one end, Bluetooth data out the other. The products to be enabled - PDAs, cell phones, notebooks - already exist. Early adopters want a complete modular solution they can add to get these products to market and establish their presence in Bluetooth.
Products already in the market are also being considered. During this first generation there will be Bluetooth adapters, such as a Bluetooth PCMCIA card for today's laptop. In the case of cell phones, the Bluetooth module can go inside a battery pack to be sold as an accessory. Most cell phones now have a data connection in the batteries, not just two terminals, which gets the user into the phone. This capability would enable existing phones to be updated for Bluetooth.
The biggest hurdle today to the high-volume market for Bluetooth is interoperability. Bluetooth is a specification anyone can download from the Web. But even when well executed, it might miss the interoperability mark. For Bluetooth to succeed, its implementation must talk to an Ericsson phone, which must talk to a 3Com Palm, which must talk someone else's Bluetooth product. There is considerable scope for interpretation in the specifications. Anyone building a Bluetooth product must be able to ensure interoperability through testing before taking it to market. The SIG committee is setting up interoperability testing for compliance, but presently most manufacturers with so-called Bluetooth-enabled products have tested them by communicating with their own products.
The key, of course, is how a product works with someone else's - this must be solved over the next six months. It is fundamental to the technology's success because Bluetooth will not be for phones or PCs only. Eventually it is expected to go into all sorts of devices from electronic toys to refrigerators, and longer term may become part of e-commerce. Ideally, a user should be able to buy an airline ticket over his Web-browsing cell phone, and have the airline Bluetooth system at the airport recognize him through his secure system as he walks by, making it unnecessary for him to stand in line, and have his electronically issued boarding pass waiting for him at the gate.
A major Bluetooth player, speaking off the record, expressed concern over semiconductor companies being able to make money with a $5 complete Bluetooth solution. As he put it, "We can make all sorts of noises about economy of scale, and that there will be hundreds of millions of products being put out. But lest we forget - aside from interoperability concerns - we're talking about a 2.4 GHz system with pretty good sensitivity. Initially, semiconductor companies are going to suffer, but they are better prepared for that. It's a novel radio architecture and there are ways to getting around cost problems, possibly taking a direct conversion approach to eliminate some of the filtering and reduce component numbers, moving the processor to the host. There are ways to address this, but the major obstacle is that there's not one uniform approach for everyone."
At least in the beginning, King Bluetooth will have to swing his axe carefully.
HARALD BLUETOOTH, KING OF DENMARK
Throughout its early history, Denmark had many contacts with the outside world, but with the beginning of the Viking Age, c. 800 A.D., it became part of European history. The Danes became most notorious as the raiders who plundered churches and monasteries.
When King Gorm the Old was the ruler of all Jutland, Denmark's main peninsula during the 10th century, Viking society was very insular and suspicious of strangers. It was ruled by so-called "great men", warlords rather than farmers, who created a number of short-lived kingdoms and claimed new lands and subjects. Often, prisoners were turned into slaves. In 908, Gorm's wife, Thyre, had a son they called Harald.
When the ruthless Norwegian king, Erik Blood Axe, died, Harald's sister Gunhild was widowed. She traveled to Denmark seeking Harald's help to secure control in Norway. Harald took the opportunity to seize control for himself, and by 960, he ruled over Denmark and Norway. He moved from Jutland to Roskilde, near modern Copenhagen. To defend his kingdom, Harald built solid ringed fortresses at strategic sites. He also had many bridges constructed, including one almost a kilometer long. It was during this period that he became known as Harald Blåtand (Bluetooth)-probably taken from two old Danish words, "blå" meaning dark-skinned and "tan" meaning great man.
At the height of his rule, Harald erected a monument that read: King Harald raised this monument to the memory of Gorm, his father, and Thyre, his mother.
Harald married twice. His second wife, Tove, gave him two sons: Sven Fork-Beard in 945, and Thyra in 958. It was rumored Sven was born out of wedlock. In any case, he was raised in the household of the Danish "great man" Palnatoke.
Palnatoke, the "great man" raising Harald's son, would boast of his marksmanship with the bow and arrow, when in his cups. Tired of the claims, Harald ordered him to place an apple on his son's head and shoot it down with an arrow. Although successful, Palnatoke turned against Harald. The enmity grew, and eventually Palnatoke created a rift between Harald and Sven Fork-Beard that grew into open hostility between father and son.
Eventually, Sven Fork-Beard headed a rebellion against his father that ended in a battle in 987. As he fled the fighting, Harald was struck by an arrow from Palnatoke, dying soon after, and Sven became king. In Viking tradition the dead were burned in a ship that was later covered with earth to create a large grave mound. In his grave, a Viking had all he needed for his final journey, such as his horse, weapons, jewelry, and food.
Since Harald had converted to Christianity in 960, he was buried without cremation - then proscribed by the new faith. His body was taken to Roskilde for burial at the church he had built there. To the present day, Roskilde retains a memorial to Harald I, king of all Denmark.