Bluetooth is a technology with a long and difficult development history that has seen it change identity with all the aplomb of a chameleon. But some claim it has lost its way through the changes? Steve Rogerson sends a health check from this year’s Bluetooth World Congress.

The Bluetooth industry nervously celebrated the technology’s fifth birthday at the Bluetooth World Congress in Amsterdam in June. Nervously, despite curves showing a steady growth and market watchers predicting more growth; nervously, because those curves are below the levels proponents wanted and nervously because the overall market has yet to accept the technology as a major player.

On the surface, the figures look good. After a total of 40 million units equipped with Bluetooth shipped in 2001 and 2002, shipments in this year alone are set to hit the 75 to 80 million units mark. Despite this, however, the market acceptance appears poor. Indeed, according to a survey by Frost & Sullivan, Bluetooth has registered little more than a blip on the corporate radar.

The survey looked at companies across 11 countries in Europe and found 69% had no plans to use Bluetooth, 22% were thinking about it and only 9% were already using it. Compare that with wireless LAN where 42% are already using it and 15% have the technology in their plans for the next 12 to 18 months.
“The penetration of enterprises is fairly low,” said Michael Wall, an industry analyst at Frost & Sullivan, “but there are signs that it could improve.”

However, the Bluetooth industry is facing an identity crisis. Whereas it would like to be a corporate player, it knows that its base market so far is in the consumer sector, but it also knows that if all Bluetooth succeeds in being is the technology of choice for connecting headsets to mobile phones, then it will have failed. Perhaps it was this that evoked a note of desperation in some of the speakers. There were even noticeable groans when John Hodgson, chief executive officer at Cambridge Silicon Radio one of the pioneers of Bluetooth, said confidently that the killer application for Bluetooth would be linking hi-fi systems with their speakers.

Dead-end niches

No one would deny that this is a possible niche market for the industry and one that should be investigated, but to say that is the killer application that will drive Bluetooth forward is not what the industry wants to hear.

In fairness, Hodgson was confident about the technolgy’s future in general, announcing that Bluetooth will ship twice as many units as Wi-Fi this year even though it has been around only half as long. The target though he said was 500 million units a year and to reach that he said, “We need to do a lot better as a community.”

A better base on which the industry can build its future is the automotive market, and on that just about everyone was agreed. New safety regulations implemented and on the horizon look set to outlaw drivers with mobile phones to their ears. There is also a reluctance to promote driving with bits of cable across drivers’ bodies as this potentially poses a safety hazard as well. A handsfree kit utilising a wireless technology seems the obvious answer, and Bluetooth is ideally placed for that.

Ibrahim Mohamed, senior product development manager for AT&T Wireless Services in the US, explained how momentum was now building stating that, “Any distraction in the car is a distraction. A lot of people are talking about distractions and not just phones.” But, safety he said, was not the only driver (pardon the pun) in the automotive market, pointing to statistics that show 60–70% of all calls from mobiles in the US are from within a car. Users in their cars have no communications alternative and therefore making calling easier and safer could be seen as a revenue generator for mobile operators.

“We need to make this convenient and high quality for the user,” he said. “Bluetooth makes it easier to make calls and is the only real universal car kit.”

Others, however, were still looking to the so-called personal area network (PAN) as the saviour for Bluetooth, prompting Alex Hum, a senior research and development manager at Orange France, to say, “We don’t talk about killer applications but a killer environment where what is personal to the user is important.”

PAN promise

True, you might say, but he then raised a few eyebrows among those calling for the jargon in the industry to be reduced when he said operators should become “life service providers,” offering a range of devices to consumers. And, he closed a few ears when he took his predictions into the world of science fiction with talk of rings that can monitor temperature, moisture and so on and thus make decisions about a person’s state of mind and trigger calls to them based on that.
“The ring could trigger a call to a friend saying the person needs cheering up so give them a call,” he said. “This can generate call revenue.”

Such a suggestion seems to smack of desperation again and is not the type of practical, here and now application that people are looking for.

Despite such silliness, the idea of the PAN is potentially sound. It refers to a situation where Bluetooth acts a cloud connecting different devices that a person may be carrying. In fact, the new version of the Bluetooth standard — 1.2 due to be implemented in September — includes an upgrade that lets such devices share the bandwidth more intelligently.

Personal gateway

Helping this along is personal mobile gateway (PMG), a technology from IXI Mobile that can build applications on top of Bluetooth. “European and Asian operators see PMG as an opportunity to increase ARPU,” said Joyce Putscher, a director at market watcher In-Stat MDR. “US operators are lagging in this, being only at the earliest stages of investigation.”

The concept behind PMG is that nearly all phones are built as talking devices first and still only a small percentage are built as all-in-one devices but they are the high consumers of data. What PMG does is turn a normal talking phone into a wireless router for other data devices. “The reason people don’t use data services,” explained Hans Reisgies, business development manager at IXI Mobile, “is the user interface on a phone. It is not conducive to using data, so PMG can route the data through Bluetooth to a thin client device such as a text manager. PMG acts as a router and server in a low cost cell phone.”

The idea is that whereas the cost of an all-singing combined phone, camera and PDA may make some baulk, especially among the younger audience, using PMG lets the user buy the phone first and then add to it as time goes by and new services make data functionality more compelling. Reisgies said he expected three or four operators to launch PMG phones and devices this year, but Putscher believes that operators are only looking at using these devices for initial trials and what happens next will depend on the results of those trials.

“There probably will be some devices this year and more next year,” she said.
IXI though, is not keeping all its eggs in the Bluetooth basket and is making sure the technology will work just as well with wireless LANs and Bluetooth rivals such as Zigbee. “Our architecture is not dependent on the technology,” said Reisgies.

No interference

The Bluetooth industry itself has taken the first steps in acknowledging that it too must work with other technologies rather than competing against them. This has manifest itself in the alteration of the Bluetooth specification to stop interference problems when Bluetooth is sharing space with, say, a wireless LAN. Version 1.2 has a frequency hopping system that avoids frequencies that other technologies are using. This version also aims to improve connection times and quality of service and closes a security loophole that could let a hacker acquire access codes by scanning for Bluetooth transmissions.

“The only hacking threat we know about is covered in 1.2’s anonymity mode,” said Mike McCamon, executive director of the Bluetooth SIG. “And even then, Bluetooth is a short range technology, so you have to be close to make an attack. We know of no-one who has broken into a Bluetooth link, and that is not the case with other wireless technologies.”

Despite such reassurances security worries remain, particularly surrounding Feel technology. This is being developed jointly by Sony and Cambridge Silicon Radio and refers to a situation in which devices close to one another will automatically make the Bluetooth connection and in some cases even transfer files without user interference. For example, a digital camera placed next to a laptop could automatically download its photographs.

It has been developed for the best of reasons — in response to complaints that Bluetooth is difficult to use — but from the initial response the developers know that if Bluetooth is to be accepted in an already cautious corporate market, then safeguards must be placed on such a development.

Feel technology maybe a Bluetooth offshoot but it encapsulates the dilemma the technology faces. The industry is worried that Bluetooth is going to be left behind and so is striving for innovation but such innovation can only succeed if it is firmly routed in reality. It must have the maturity to convince potential users that the ideas behind it are solid.

Bluetooth technology does have a lot of potential and does have markets where it provides a clear advantage, the automotive sector being an obvious example. It is also positive that it is acknowledging by changing its own specifications that working with other wireless technologies is a must. Building on these sensibly is the way forward for Bluetooth, thrashing around desperately looking for new and ever more far-fetched markets is a sure fire route to nowhere. It is clear from the attendees at this year’s centrepiece that both camps are still alive and kicking. Which one will win only time will tell but it is in the industry’s own hands.

When the first GSM base stations were installed vehicle-mounted mobile phones routinely failed at cell boundaries. Now, 12 years on, a new technology is being introduced and we are forced to ask, are dropped calls a necessary part of the UMTS learning curve? Achim Grolman of Willtek Communications assesses the problems and how they are being solved.

Compared to American CDMA wireless standards, UMTS defines far more network elements and interfaces. This has been done deliberately as such granularity gives operators, for each entity, the choice between multiple vendors to buy the best products. However, the evolutionary nature of standards means that vendors may initially follow different interpretations of the UMTS specifications. This means that operators face a complex task to make systems work effectively from the outset and that requires a lot of testing and discussions with different suppliers. This will come as no surprise to those familiar with the development of cellular infrastructure as there are no conformance test cases for the network elements as there are for terminals.

In the early 1990s, it took two to three years to get GSM networks going. For 3G, the complexity of integrating telecoms and IT network elements has added to the problem experienced then and, in truth, it is surprising how well the first 3G networks are already operating.

As real network elements are knitted together, problems in the specifications are discovered and resolved, which means specifications are constantly being fine tuned. This process directly impacts on the testing environment as conformance test specifications have to follow these changes; test equipment and test cases then need to be validated. This is why test equipment is often not available before the network elements as test equipment and network elements are developing in parallel in the early stages of a new standard.

Installing the RAN

3G network operators have already installed base stations (or Node Bs to use UMTS jargon) and radio network controllers in major cities. Installation in smaller towns and urban areas is also progressing although much more slowly as there is little revenue from the existing 3G networks to pay for further rollout. 3G is being installed under strict financial controls and that means attempting to optimise the design of the network.

To this end, simulation tools are in place to determine the best locations for the base stations. Yet, to be effective these tools need to be calibrated with real-life tests using constant wave or W-CDMA transmitters, measuring receivers and RF propagation test software. These efforts can minimise problems later, such as the need to acquire additional sites later.

Operators have learned from less-than-optimal network layouts and configurations in the early GSM phase.  For example, back then dozens of engineers from different vendors circulated London to find out why their phones lost calls along the M25 in spite of strong carrier signals. Add to this the fact that W-CDMA behaves differently to GSM, making in-fill more complicated, and the benefits of taking the time to plan the network as effectively as possible is clear. However, getting it right in theory and practice are not necessarily the same. Therefore, once installed, radio networks are verified and optimised with the help of test mobiles and drive test software, pinpointing coverage gaps or problems due to cell reselections occurring unnecessarily and/or too often.

Handover techniques

There may only be a few UMTS phones available on the market – first-tier vendors of mobile phones are introducing their first-generation models now – but to be fair, these phones and the networks they are operating on, already support most of what customers are used to from GSM phones: voice, SMS, MMS, WAP and web over packet data channels. But customer expectations are high and, on a technical level, the handover of a call from cell to cell, now highly reliable in GSM, provides a very specific additional challenge.

There are, in fact, several handover techniques in UMTS. Adjacent cells using the same carrier frequency perform a soft hand-off. In this both base stations hold a connection to the phone for some time so ideally, there is no disruption in the call. The softer hand-off takes the phone from one antenna sector to another of the same base station. A hard hand-off (which breaks the existing connection before making the new one) however, occurs when the carrier frequency is changed.

As Europe demands dual mode operation, a special case inter-RAT (Radio Access Technology) hard handover occurs when a call is transferred between UMTS and GSM. It is a new requirement and technically challenging. Indeed, the first successful handover from UMTS to GSM was only achieved by Ericsson less than a year ago and therefore it is a function that has not been supported by early 3G networks.

The core network provides the link between both radio access technologies. When a UMTS call is due to be handed over to a GSM base station, the core network requests information about the new channel from the GSM base station system. While the handover message is usually sent to the phone via a GSM base station, the BSS now sends it to the core network which in turn encapsulates the normal GSM handover message in a UMTS handover message. This way, the GSM protocol stack in the phone can interpret the data and set frequency, timeslot and other parameters accordingly although the message is transmitted over the UMTS interface.

Changing times

It is a complicated process and internal test methods and equipment to analyse software interfaces are proprietary, at least for each first-tier vendor of terminal equipment. Later on, second and third tiers will benefit from third-party tools and software written around generally available GSM/UMTS chipsets.

In addition to testing hardware and software modules within the phone, measurements of the overall performance are required and vendors have to prove that their products are up to standards. Although UMTS protocol testers are available, the majority of the test cases are not, since they take some time to develop. RF and protocol specification go first, then the conformance tests, and at the end of this chain, test case implementations from test equipment suppliers need to be validated. Note also that the Inter-RAT protocol is still being optimised!
One of these optimisations concerns adjacent cell measurements. In order to hand over the call to the best suitable base station at the cell boundary, the network needs information from the phone regarding the received signal strength and quality of the surrounding cells. This is easily possible with the TDMA nature of GSM which leaves enough time for the phone to monitor adjacent base stations. However, UMTS-FDD calls are transmitted and received using permanent carriers. Only with the introduction of the compressed mode where the user signal provided at constant bit rate, can it be transmitted at a higher rate for some time, thus leaving a gap which the mobile can use for adjacent cell measurements on different frequencies. An alternative would be dual-receiver designs where the mobile phone can receive on the assigned channel with one receiver and on the neighbouring cell carriers with another. This approach, however, is more costly in terms of components, weight, power consumption and battery life.

Now that the network knows the best base station to hand over the call to, it provides the phone with information about the new carrier. Depending on the direction in which the call changes from one radio access technology to another, the terminal has 40 to 120ms (without preceding synchronisation) or even up to 220ms (in the unsynchronised case) time to switch technologies, synchronise in frequency and time to the new base station, set up the protocol, and continue the call. One design approach, commonly used in early models, uses separate base band chips for GSM and UMTS which are more difficult to synchronise during handover. However, even the other approach, a combined chip, still poses a challenge in terms of both hardware and software design.

While data connections are regarded as something of a special case now, they are expected to become more common with 3G. The problem there are a few applications will not survive the cell change order procedure because they time out before the mobile has synchronised and set up the link to the new base station. UMTS equipment will support concurrent voice and data connections. The data part, however, will most likely be lost in a UMTS to GSM handover because phones do not support both connections at the same time in GSM. This problem may be solved with voice over IP over both UMTS and GSM/GPRS.

As is becoming more obvious as we move through the 3G structure, it is much more complicated. Furthermore, the absence of protocol testers fully supporting these procedures to test both phones and networks, means all parties involved have to find a different method.

Alternative test route

This began when manufacturers of phones and network elements announced bilateral cooperation agreements years ago to further their 3G developments, but interoperability tests between virtually all manufacturers are required and are being executed now. This can be time-consuming but should not be seen as a luxury as it will avoid situations such as the one that occurred two years ago when a major handset maker had to withdraw its GPRS phone from the market because it did not work with one network vendor’s equipment. Interoperability tests are especially important for standards which are open to interpretation and/or provide many different options for doing the same. In other words, they are vital for new, emerging technologies.

When the first stable versions of the UMTS standard came out, people expected ‘UMTS islands in a sea of GSM’ and to many it was natural to believe (or demand) that from day 1, terminals would be capable of handing over voice and data calls between GSM and UMTS. Reality, however, shows us that the handover has never been the first function to work with a new cellular standard, be it 1G, 2G, 2.5G or 3G. Engineers still need time to optimise hardware and software designs, especially in the handsets. There is much pressure from operators to get handovers working because dropped calls are the first things that customers discover to be wrong with the network and are a major obstacle to success. But this does not mean that UMTS doesn’t work — it simply does not fully support this feature – yet. It is only a question of a few months until new GSM/UMTS phones are available, allowing users to seamlessly roam across air interface technology barriers.

Operators are being driven to reduce costs while at the same time rolling out complex new services to grow average revenue per user (ARPU) — they are stuck between a rock and a hard place. Jeff Atkins of Actix explains how software that uses key data from the radio access network can lead to significantly improved productivity, resulting in lower costs and an improved ability to roll out and optimise new services.

The once simple job of radio network optimisation, using just drive test equipment, is rapidly becoming obsolete as the challenges of debugging new data services bring new complexity to troubleshooting and optimisation processes. New and more advance equipment is needed to keep pace. Indeed, market analyst firm Frost & Sullivan expects the market for wireless test equipment to increase to $1.91billion by 2009 from $1.33bn last year, as the delivery of wireless services becomes more complex.

Because the radio link is known to be the weakest link in the wireless provider’s network, it is traditionally the first place to look when service problems with voice networks occurred. However, with complex new technology like 3G, subscriber perceived service problems such as: low data throughput can arise from a variety of causes including unplanned server downtime, internet congestion and core network dimensioning, as well as coverage or interference issues in the radio network. However, before engineers can begin to solve the problem, they must first be able to isolate the portion of the network responsible for the problem.
 
To achieve this it is necessary to have an “end-to-end” view of network performance and that is only possible by correlating data from a number of different sources — drive test equipment, infrastructure vendors’ proprietary call trace logs, protocol analyser logs from open radio and core network interfaces and IP “sniffer” logs. That’s why it’s more important than ever to be able to get access to these various sources in a single platform.

To optimise and troubleshoot a 3G network effectively, performance data needs to be collected from a variety of points in the 3G RAN. It is only by utilising data from a combination of sources that a full picture of the performance of the network can be obtained. For example, to find out that an FTP proxy is related to low throughput and to understand how best to correct the problem, TCP IP logs and drive test data need to be correlated on a common platform.

Information collection points

The most common sources can be seen in the image above and include: the air-interface (Uu), RNC-Node B interface (lub), RNC-MSC interface (lu CS), RNC-SGSN interface (lu PS), and Performance Counters and Measurement Programs (OMC).
Each information collection point offers different strengths and weaknesses in areas such as the type of information that can be obtained (e.g. radio link information, circuit call information, or packet data information), the availability of data collection devices like handsets, the granularity of data which effects its ability to be used to solve specific problems, the ease and cost of collection, and the volume of data that can be collected. Wherever that data comes from, once collected, it must be filtered and reduced before it can be used to make decisions on improving network performance. In addition, collecting and analysing various sources of data at the same time allows efficient utilisation of resources.

Subscriber perspective

Using equipment available from a variety of vendors, operators can drive around their network measuring performance from the perspective of the subscriber. The equipment needed to do this typically comprises a special test mobile phone and wideband scanner, connected directly to a laptop, or indirectly through an intermediate hardware device. The scanners are used to passively measure desired and interfering RF signals from base stations faster and with better accuracy than test mobiles and therefore they compliment the measurements available from the phone. In many cases, scanners can detect the underlying RF causes of the performance problems detected by test mobiles. Some vendors also offer drive test equipment that can be operated by remote control, allowing equipment to be placed in technicians’ vehicles or fleet vehicles (such as taxi cabs), for automatic data collection.

In addition, proprietary measurement programs that run on the switch or RNC enable operators to collect performance data for specified mobile phone numbers. The log files are often used to collect uplink performance metrics to complement the downlink performance measured during drive tests. These log files may be synchronised to drive test data or used independently.

Straight from source

Using protocol analysers available from a number of vendors, operators can collect performance data directly from key infrastructure interface points including the Iu CS, Iu PS, and Iub interfaces. Because these interfaces are based on open standards, the development of collection equipment and analysis software can be completed during infrastructure development. It is then available for use during the planning and lab/field trial phases prior to system launch. Protocol analysers come next and collect a wide range of data, from performance data on the packet and circuit interfaces, down to RF data as reported by the User Equipment.

OMC Performance counters are vendor-specific, proprietary statistical counters of key network events at a network element level of resolution (e.g. statistics for a cell). Operators have traditionally relied on performance counters to monitor the high-level performance of their networks, either using collection software provided by the vendor, third party software, or by building in-house systems. 

Once data has been collected from all sources, it must be processed, analysed and archived. The processing of the data can be challenging for a number of reasons. Firstly, operators typically have a number of vendors for different types of drive test and protocol analyser equipment, each with a unique interface format. Operators also often use measurement programs from different technology networks (e.g. GSM and WCDMA) and/or different infrastructure vendors, each with a unique interface format.

Data sets collected at different interface points may need to be synchronised so that they can be merged for troubleshooting across network elements. The sets may also be extremely large (many gigabytes), and key information must be filtered and reduced before it can be used to make decisions. Finally, formats are constantly being updated and the technology of the air-interface is constantly changing (e.g. 3G rolling out on the back of 2.5G technology). This means that many engineers have limited training and experience with newer technologies.

Multiple function support

To enable operators to use the data effectively, their data analysis platforms must support a range of functionalities. These include supporting interfaces to a variety of vendors of drive test equipment, protocol analysers, and measurement programs and providing support for open interfaces, which can typically be used to collect performance data well in advance of proprietary data sources, like test mobile and peg counter data. Other important functionalities include supporting multiple technologies on one platform simultaneously (e.g. GSM/GPRS and WCDMA), reducing data through binning and standard database type querying and filtering capabilities, and synchronising data collected from different network elements and sources to remove timing discrepancies. Providing interfaces into databases for storing collected data statistics and provide web-enabled reporting interfaces for extracting data is also a key function, as well as supporting the latest technologies and vendor formats, and providing a user interface that allows less experienced engineers to become effective quickly.  Finally, analysis platforms need to be able to embed engineering expertise into software to automate the process of analysing large amounts of data.

Data collection

A system can be designed to collect data from all available links from the air-interface through to the switch/SGSN. Data can be collected in discrete log files and processed through a desktop application for manual, on-the-spot analysis. It can be collected from any source and processed and loaded into a database system from which it may be served up through a web browser or other client.

Mobilkom is one of the first European mobile operators to launch its public UMTS network, having selected Actix’ RVS and ANR solutions to be at the heart of its network optimisation strategy. Testing using Actix’ solutions began in mid-December 2002 and the network went live on the 16th April 2003. Other operators that use Actix’ 3G technology include Swisscom and Hutchinson’s 3G networks in both the UK and Italy.

These operators are streamlining their process — doing it faster and better — ANR and RVS are being used to embed processes into software, accelerating the rate at which rollout can be accomplished, reducing the impact of not having many engineers that are skilled with 3G technology by embedding expertise into the platform, and offering better quality of service by performing complex analyses of problems not previously possible.

Ultimately, being able to bring 3G services to market faster and provide an enhanced end user experience will be critical to operators taking advan-tage of the only foreseeable long-term revenue growth opportunity.