The growth of short range wireless systems, especially Bluetooth and wireless local area networks (WLAN) has captured the industry’s imagination, if not the market that was initially predicted. Bluetooth technology originated in Europe, with early research and development driven by European-based organizations. In this supplement that is special Journal reviews current European activity, global expansion and globally competing technologies to find whether going wireless includes strings attached.
No cables — what an proposition that is attractive! Consider the savings in cabling costs and flexibility offered if an office’s computers were served by a WLAN. Just imagine being able to eliminate the tangled mass of wires presently required to connect a PC, not only towards the network, but also to its peripherals such as for example the keyboard, mouse and printer. Meanwhile, the mobility of cellular and technology that is cordless promoted a few ideas for a generic short range wireless access solution for different products.
These are all desirable aims but the curiosity about and development of brief range wireless information networking hasn’t just been prompted by the necessity to office that is disentangle from trailing wires. The real impetus has result from the desire and expectation of people and companies in order to access data and information very nearly anytime, anywhere, any place. Laptop-based users and broadband access in homes are more of the elements converging to drive ideas of a short range wireless access solution as well. Ally that with the prospect of vast numbers of cell phones becoming Internet enabled with users wanting to link up to laptops, headsets, hands-free kits and LAN access points, and a lucrative market is guaranteed so long as the technology can be acquired to implement it.
With such a big and untapped market there has been no shortage of contenders vying to provide that technology. This article looks at two of the leading contenders, Bluetooth and WLANs. Issues covered include how Bluetooth has generated on its European origins and early development to capitalize on Europe’s Global System for Mobile Communications (GSM) to enable it and synergize with it, together with the opportunities that 3G could offer. By mapping WLAN development and global deployment it is regarded as both a competing technology and development market in a unique right.
BLUETOOTH: AN OVERVIEW
Since Ericsson originally devised the technology in 1994 Bluetooth has grabbed the imagination and most for the headlines. The company continued taking care of the project alone until February 1998, when it shared Nokia, Intel to its research, IBM and Toshiba to found the Bluetooth Special Interest Group (SIG). The main purpose of the SIG is protect the integrity of this technology and control its development. It really is responsible for the certification process that most devices must complete before they could be acknowledged as having a Bluetooth compliant product. Without certification, a product cannot claim to be Bluetooth-enabled or make use of the Bluetooth trademark. The certification process ensures that developers keep to the standard and make sure interoperability.
The specification that is commercial Bluetooth 1.0, was issued in July 1999 and ratified in February of this year. The growth of activity in the technology is illustrated by the fact that there are currently some 2000 companies working on or developing products based on this specification. From its European origins — it’s known as after a 10th century Norwegian King — Bluetooth has inevitably become of worldwide interest to both manufacturers and prospective users.
The attraction is Bluetooth could offer cost that is low small physical size (single chip) and low power consumption over throughput and range. Allied to its capability to function in noisy radio environments and offer transmission that is high. These features, together with help for real-time traffic of both sound and data, make it an attractive wireless networking technology for personal digital assistants (PDA), mobile phones and laptops.
Licensed range is expensive, particularly in Europe ([greater than] $100 billion covered 140 MHz). An important appeal of Bluetooth is that it runs at the internationally available unlicensed commercial, medical and medical (ISM) 2.4 GHz frequency musical organization, allowing compatibility that is worldwide. Figure 1 shows the European 3G spectrum cost vs. the WLAN spectrum (83.5 MHz in the 2.4 GHz band and 455 MHz into the 5 GHz band) free of charge. Bluetooth wireless technology operates in a multiple piconet topology (see Figure 2) that supports point-to-point and point-to-multipoint connections. With the specification that is current up to seven servant devices may be set to communicate with a master radio in a single unit. As Figure 3 illustrates, a number of these piconets are founded and linked together in advertising hoc scatternets allowing communication among continually flexible configurations. All devices in the piconet that is same priority synchronization, but other devices are set to enter.
Bluetooth’s baseband technology supports both synchronous connection orientated (SCO) links for voice and asynchronous connectionless (AC) links for packet data. Both utilize time division duplex (TDD) as the access technique for full duplex transmission. Voice coding is accomplished using a continuously variable slope delta (CVSD) modulation method, under which voice packets should never be retransmitted. The master unit controls the web link bandwidth and chooses how bandwidth that is much give each servant and slaves must be polled before transmission.
An channel that is asynchronous transmits data can support an asymmetric link of 721 kbps in either direction and permit 57.6 kbps in return. For a symmetric link the channel can support 432.6 kbps. Since Bluetooth devices can support three voice channels operating at 64 kbps, or one data channel, they can attain data rates of up to 1Mbps. The Bluetooth 1.0 specification calls for 1 mW transmitters with a antenna that is nominal of 0 dBm to operate as much as 10 m (type of sight). A greater power transmitter of 100 mW (+20 dBm) included in the specification increases the product range to 100 m, even though this will require a separate PA antenna driver. The compromise is increased expenses and energy usage.
Bluetooth uses regularity spread that is hopping (FHSS) technology, where the system will frequency hop 1,600 times a second, delivering short time division multiplexed packets with each hop. With spread spectrum hopping, the sequence is random and the receiver must hunt down the chosen transmission frequency after each hop. Before any connections in a piconet are created, all devices are in standby mode which allows for the device to listen on 32 hop frequencies defined for each unit, for messages every 1.28 seconds. The text starts whenever one device initiates a link and becomes the master associated with the piconet. A connection is made by a page message then an inquiry message followed by a page message is sent if the address is known, and if it is not. The devices synchronize and connect then. Each device assumes a media access control (MAC) address to distinguish them at the point of connection.
The Bluetooth specification that is technical be clear, product roll-out less so. The marketing machines did their job in creating awareness but in the process raised expectations that have yet to be fulfilled. All too quickly allegations, particularly in the media, of over hype and over elaborate market forecasts were hitting the headlines. However, last year saw a significant number of product launches together with the initial shipments of products bearing the Bluetooth logo. There has been consolidation for the first half of this 12 months aided by the end of 2001 seeing significant predictions.
Frost & Sullivan forecasts worldwide deliveries of Bluetooth-enabled products to reach over 11 million units in 2001, equaling $2.5 billion in profits, while Micrologic Research is more conservative using its estimation that the marketplace shall reach five million devices in 2001 and 1.2 billion in 2005. Such variations in figures tend to muddy the waters and emphasize the unpredictability of the market, but in such an technology that is embryonic is perhaps understandable.
That is a true point made by Michael Wall, research analyst at Frost & Sullivan, who has stated: “Although the delays in the development of Bluetooth are beginning to prompt a backlash from certain sections of the media, industry observers have to take the infancy of Bluetooth as an industry standard technology into consideration when assessing the status of this marketplace. Apart from Ericsson, the pioneers that are original perhaps the most progressive designers are not drawn to the project until 1998. Other communications that are mobile such as for instance the GSM took longer to develop than will be allowed for Bluetooth.”
Semiconductor chipset development is an integral aspect in the technology’s progress, with a range of development models emerging within the semiconductor industry that is bluetooth. Two distinct manufacturing routes are now being taken. There are either those offering complete integrated solutions through the silicon wafer level to your consumer product degree or those providing part of the sum of a chipset, that is, baseband, radio and software.
Debate continues over the absolute most effective choice of silicon technology for Bluetooth. The diversity of silicon technologies and solutions architectures being used has emphasized the software protocol stack. It has become one of the most crucial elements of the solution, especially with regards to achieving interoperability and will end up increasingly essential as semiconductor companies come closer to establishing their products onto the market.
A number of smaller design services companies have entered the Bluetooth software market offering complete or partial protocol stacks to semiconductor developers alongside some of the big names. In the same vein Bluetooth has offered a number of smaller, highly innovative fabless semiconductor developers, such as Cambridge Silicon Radio and Silicon Wave, an opportunity to build early market share with fast time-to-market solutions. Between the larger built-in Bluetooth developers, Philips Semiconductors has been the main player to offer solutions in volume. It is expected that a number that is large of will be on offer by the conclusion of 2001.
Market success may be decided by a egg and chicken combination of chipset supply. Observers have warned that restrictions in the supply of chipsets to smaller product developers may cause delays in the time-to-market of new innovative applications that will provide future revenue streams for chipset vendors. Despite such words of caution Frost & Sullivan forecasts that the sum total deliveries of Bluetooth chipsets will likely be over 956 million in 2006, therefore the total market for these chipsets is predicted to be over $2.3 billion in 2006. Further up the value chain from chipsets the early Bluetooth offerings are fairly generic wireless community access products, such as for example PC cards along with other add-on products, along with access points (AP).
Additionally, in European countries, a number that is significant of mobile phones were launched at the CeBIT exhibition in Germany in March 2001 with many more expected over the summer. However, the market cocktail has become more intriguing because of 30 market developments. At a time when the huge cost of 3G licenses is impacting on the telecoms stock exchange as well as the equipment needed to roll-out Universal Mobile Telecommunication System (UMTS) systems have not yet visited fruition, lots of the solutions planned for 3G mobile could possibly be delivered by now available technologies which run in unlicensed (free) regularity bands.
Mobile operators who have 3G permit debts to service are under some pressure to maximize revenue of existing data services, and indicate that the market has got the appetite for 2.5G and services that are 3G. Bluetooth mobile phones could be one solution by allowing users access to the Internet on their PDA using the phone as a wireless gateway. Ericsson, for instance, is promoting the bluetooth information that is local (BLIP), which provides Bluetooth access to the Internet, within range of a BLIP access point. Such developments will continue to keep Bluetooth in the headlines and the eye that is public.
WLANs are emerging through the wings as a strong contender to rival Bluetooth. WLANs enable the Ethernet cable from the wall outlet to a device (such as a PC) to be replaced by a wireless link between an access point and an invisible screen card that is either area of the wireless unit or connected to it. The technology is in no real way a newcomer, however. The IEEE 802.11 in fact, it was back in 1990 when, in the US Wireless geographic area Networks Standards performing Group was formed with the task of developing a standard that is global radio equipment and networks running within the 2.4GHz unlicensed frequency musical organization for data prices of 1 and 2 Mbps.
Over a decade ago what the initial 802.11 standard did, to a diploma, had been to aid unify a confused WLAN marketplace, which was crowded with proprietary solutions. Although the specification that is original three different transmission media — frequency hopping spread spectrum (FHSS), direct sequence spread spectrum (DSSS) and infrared (IR) — the major area of development has been for DSSS. DSSS spreads the signal over several frequencies, can switch channels to avoid interference and also makes the signal harder to intercept than standard wired Ethernet.
The IEEE 802.11 standard had been used in 1997. The modulation scheme used whenever operating during the 1 Mbps rate is phase that is binary keying (BPSK) where each symbol carries one bit and one million symbols per second (1 Msps) are transmitted. Thus, with each symbol storing one bit, the bit-rate achieved is 1 Mbps. Quadrature phase shift keying (QPSK) is the modulation scheme used to yield 2 Mbps. With this technique the system is able to transmit two channels simultaneously, and although the symbol rate is still 1 Msps with QPSK mapping two bits per symbol, the result yields 2 Mbps. Nonetheless, these information rates of just one Mbps and 2 Mbps are considerably slow compared to the wired LAN equivalents. This aligned with concerns over interperability and cost, restricted take up and acceptance for the standard as a viable option.
That all changed in September 1999 once the IEEE ratified a new high rate standard for WLANs – IEEE 802.11b, which also goes under the various guises of long range router (Wireless Fidelity) and high rate wireless Ethernet. It is significant because it offers a top-end data rate of 11 Mbps. Each access point can help dozens of connections, although they all must share 11 Mbps of ability. There can be three access points working in the same area, and each typically has an indoor range of 90 m at 1 Mbps and 25 m at 11 Mbps. The IEEE 802.11 b specifies complementary code keying (CCK) as the modulation scheme to achieve this higher data rate. The strategy maps four bits per icon to reach 8 Mbps, which allied to an increased rate of 1.375 Msps yields a little rate of 11 Mbps. Therefore, whilst the true number of symbols sent per second hardly varies from the symbol rate used for IEEE 802.11 LANs, more hits per second are sent. Also, as CCK is a DSSS technique, 802.11 b is backward-compatible with products that meet the origin al 802.11 specification, enabling 802.11b products that are standard interoperate with 802.11 compliant DSSS items by falling back again to 1 Mbps or 2 Mbps operation.
With a business human anatomy to verify interoperability and the interoperability of 802.11b cards being guaranteed, because of there being simply two silicon manufacturers worldwide using a similar MAC layer specification, that deficiency in the WLAN offering has been addressed. The increased bit rate of 11 Mbps has also dealt with the performance issue with 802.11b being able to match standard Ethernet for speed. This has resulted in a renewed desire for, as well as perhaps moreover, investment in the development of 802.11b items by big players who didn’t view any participation in 1 or 2 Mbps products as a viable option.
Now, the huge benefits that WLANs offer in terms of flexibility and flexibility, allied to increased speed as well as the falling costs of Computer cards, has made it an option that is attractive the home market where broadband access is growing for small businesses and particularly for the enterprise customer. Typical applications include the creation of ad hoc LANs, the linking of portables into a wired infrastructure, WLAN bridging and in peer-to-peer networks where PCs with wireless cards can exchange data directly. Instead, an access point allows PCs to keep in touch with fixed Ethernet topologies via an Ethernet hub or switch port. Although WLAN cards remain more expensive than ordinary cable-based Ethernet cards, having a means that is standard all manufacturers move to the same technology and prices come down. Today there are cards at around the $200 mark.
The main element towards the progress of WiFi is its wide and global deployment, and without any hype it has begun. Airports as far afield as Europe, Japan, Hong Kong and the US have installed networks that are 802.llb with hotels and seminar centers also being prime areas of development. Also, with all the increased use of laptops, the natural synergy between their mobility and the mobility offered by WLANs is propelling the growth of 802.llb. Offering mobility is going to be the key to success of WiFi. For instance, when users have a notebook, they want to be able to use it in the working office, at home as well as on their travels and never having to swap cards. Just a deployment that is wide of will facilitate that.
Mobile operators also see WLANs as an affordable and way that is easy provide high speed access to densely populated areas. Because they rely on very short-range transmissions, users see improved battery life, and with health risks being a concern there is the advantage that is added of power use. Once more, at CeBit there have been a large number of equipment companies showing WiFi components in the shape of PC cards, universal bus that is serialUSB) devices, access points and home gateways. However, at present the Wireless Ethernet Compatibility Alliance (WECA) only recognizes one test house in the US for certification of WiFi products with plans for a European test house become recognized soon. Such expansion is critical for the technology to truly be viewed as global with regards to development.
The main element factor in the development and development associated with WLAN market is the increased data rate of 11 Mbps being afforded by the standard that is 802.llb. However, in October last year the IEEE Standards Board approved P802.llg, a new project within the IEEE 802.1 WLAN Working Group to enhance the data rate of WLANs operating in the 2.4GHz frequency band. The expectation is that the data rates are going to be risen up to higher than 20 Mbps while the mission associated with the task group is to review proposals. Areas of development currently being undertaken which could afford this ‘doubled’ data rate add a new modulation technology that improves the robustness of RF information transmissions. It not just overcomes much of the backdrop RF noise and other resources of interference but additionally provides better performance against multipath interference.
In the receiver side, advanced technology that is equalizer in concert with these new modulation algorithms will act to reduce the need to retransmit data packets. This is important because when interference in WLANs causes corruption that is unrecoverable of reflected data stream or noisy signals are discarded and therefore are retransmitted which slows the information rate and interrupts the data movement, the system is less reliable for realtime transmission. With advanced equalizer technologies, reflected or noisy signals are not only discarded or filtered away. Ahead mistake correction (FEC) algorithms can take corrupted signals and reconstruct them, considerably reducing retransmits.
Data prices of over 20 Mbps will start applications that are new the industry to exploit. As might be expected, interest shall likely be led by leisure applications. Faster transmission speeds will enable streaming video for high definition television and graphics for interactive gaming while also providing the headroom to accommodate new applications when they come on stream. Businesses and enterprises are always screaming out for the means to transmit large amounts of data quickly. Home automation will be another avenue by facilitating the interaction of heating, lighting, air security and conditioning systems.
THE WLAN MARKET
Such applications may be a way off but the WLAN is a market that is growing the statistics show. According to the latest figures from IDC worldwide WLAN equipment revenue jumped 80% in 2000, breaking the $1 billion mark. IDC predicts that by the end of 2005 the market will be approaching $3.2 billion. Demand, especially in the US, has been particularly strong in vertical industries such as education, retail and health care. In the coming years, the market will see increased use of WLANs in the home and small- to medium-sized business (SMB) segments together with the growth of broadband. Despite the optimistic outlook for the general market, especially in the united states, Western Europe and Japan, IDC believes vendors will have to overcome a few hurdles, including resolving standardization problems, educating their partners, improving safety and reducing costs so that WLANs are affordable for mainstream sections.
The chipset market for 2.4 GHz WLAN items is set to keep to expand, although development will not be as high as for Bluetooth chipsets. Frost & Sullivan anticipates sequence 802.11b that is direct Chipsets to be in great demand, predicting that the market for them shall be worth over $1.3 billion in 2006. This demand will be driven by the growth in traveling with a laptop and by dropping item expenses.
Bluetooth and WLANs may have profiles that are differing terms of marketing and publicity but it is clear from the market statistics and investment in technical development that both are technologies that are becoming established and set to grow. However, can they coexist technically? Interference has been a topic of debate and concern since the early stages of Bluetooth development and to a extent that is certain has become a fear of the unknown. What’s known is the fact that interference between 802.1 lb and Bluetooth devices can occur. The Federal Communications Commission (FCC) requires every device operating in unlicensed bands to have a label stating that it can cause interference in the US. Nevertheless, what exactly is not known is the potential of this problem. The fact the products run in an unlicensed band and projections of mushrooming market growth for Bluetooth and 802.1lb is fueling concerns.
Even though level of concern risk turning down to be unwarranted, this has at the least grabbed the eye of wireless criteria groups, regulatory systems and wireless industry participants. They are all well aware that if users do experience interference problems it shall damage user self-confidence into the technology. With so much investment it is a risk that manufacturers, in particular, cannot take. Global development that is technical is being completed and standards are now being addressed to limit interference. In the US the IEEE 802.15.2 Task Group is coordinating efforts, and the FCC has also put together a set of rules that allow multiple devices to share the spectrum, providing room for considerable innovation in building radios that can resist interference.
Consequently, considerable research observe the result that WiFi and Bluetooth devices operating in the same vicinity have actually on a single another is under method. Results do vary and Figures 4 and 5 are samples of a particular study to illustrate the effect. However, what is generally accepted is that if the antennas of the Bluetooth and WiFi devices are kept over 2m apart, then there will be graceful degradation of the two protocols, which will only be noticed by very sensitive users. Move the 2 antennas within a meter, nevertheless, and there may be significant interference.
Interference really becomes a issue that is serious both radios are integrated into the same device with the antennas close together. Examples of when the two devices are collocated (that is, separated by less than 10cm) are in a combination PC card and laptops or Internet appliances enabled with both technologies. Also, it is believed that collocated products will play an important role in products such as for instance notebook PCs. An illustration is a notebook who has a Bluetooth radio integrated for connection to a PDA or cell phone and at precisely the same time has a WiFi radio incorporated for LAN access.
Coexistence is a major issue for such applications and one which the industry is striving to address with standards bodies and wireless companies starting to develop and lobby for a variety of coexistence approaches. These vary from regulatory intervention and special standards task forces such as IEEE 802.15.2 to various technical approaches ranging from simple device ‘collocation without any coexistence mechanisms’ to integrated silicon solutions covering the entire sub-system that is wireless.
Mobilian Corporation, as well as industry partners, is a company working on developing a solution and contains categorized these various approaches that are technical a performance and user experience hierarchy, as shown in Figure 6, with each having their strengths and limitations. ‘Collocation without a coexistence mechanism ‘is relatively controversial. It does have the advantage of being a time-to-market that is rapid which provides a single-card guide design only. The close proximity of the two radios with no coexistence device will probably create worst-case situations, and can consequently end up in significant degradation to both radios’ performance.
Dual-mode radio switching will not need modifications to your silicon, and may be fairly quick to market. It includes a coexistence mechanism that requires that while one radio is operational, the other is totally suspended. The procedure can be implemented primarily in two ways. In the first, the system simply shuts the non-operating radio off with no signaling to many other nodes in its community. This will result in difficulties for the network and will drop performance levels below that of simple ‘collocation without a coexistence mechanism.’ The second method does signal other network nodes that it is suspending one of its radios. Performance will still be 60 percent lower than that of unhindered radios because of its modal nature (one on/one off), but is much better than simply shutting the radios off. Neither method supports switching while Bluetooth vocals (SCO) links are in operation.
Driver-level transmit switching generally describes an approach by which application send requests are mediated at the motorist degree, thereby avoiding simultaneous transmission. Intuitively, this approach degrades throughput by some measure simply due to its modal transmit framework. More important, though, are its limits in avoiding collisions with incoming packets. The resulting transmission of just one protocol during reception for the other causes loss in received packets, disturbance and user that is potential. This is caused by the technique’s dependence on the host operating system, which will be broadly speaking non-deterministic in its response time (non-real-time). Once more, this method will not switch quickly sufficient to aid Bluetooth SCO links, and also will have problems mitigating the disturbance from Bluetooth piconet master/slave polling activities.
While Bluetooth adaptive hopping truly improves simultaneous performance under limited penetration scenarios, its widespread adoption will likely require intervention from regulatory organizations and standards bodies. Even under a fast-track program, this can be a process that is time-consuming. This time-delay exacerbates the issue that the strategy’s effectiveness is compromised with greater penetrations of WiFi systems and unmodified devices that are bluetooth. Adaptive hopping will likely be initiated as an Bluetooth that is optional profile indicating that modified devices will perhaps not use the functionality in piconets with unmodified devices. Further, in the presence greater than one Bluetooth piconet or WiFi network, adaptive hopping are counter effective to coexistence.
MAC-level switching is the very best associated with the style that is modal/switching, and provides performance levels approaching those in no-interference scenarios. It is a collaborative technique accomplished by trading information involving the two protocols at the MAC level and managing transmit/receive operations accordingly. Because MAC-level switching is carried out within the baseband, it is able to switch between protocols at a much faster rate than driver-level approaches. Consequently, it is able to mitigate many of the conditions that driver-level switching cannot. MAC-level switching does not suffer from transmitting signals into incoming receptions, Bluetooth polling or operating system latency. Nevertheless, it really is vunerable to adjacent-channel interference and does suffer noticeable degradation. Also, it has a longer development cycle than driver-level approaches because it is located in the baseband.
Simultaneous procedure provides the capacity to immediately detect all available networks that are wireless select the ones needed and connect to them seamlessly. By providing coexistence in a highly integrated two-chip solution – an analog front-end chip and an electronic digital baseband chip – it allows simultaneous procedure associated with the two protocols while eliminating disturbance and maintaining reliability and gratification. Interference is a concern that is genuine, as has been illustrated, there are measures that can be taken and innovative initiatives under development to provide coexistence particularly for collocated devices. The potential market is too large and too lucrative for every effort not to be made to ensure smooth operation.
BLUETOOTH vs. WLAN APPLICATIONS
Bluetooth and WLAN may be competing within the same frequency band but are they competing for the same applications? Due to its simplicity in not having to be configured, low power, short range and low cost Bluetooth will be focused on small devices such as PDAs and cell phones. To provide access and synchronization of those devices that are personal is likewise the need for Bluetooth radios to be incorporated in access points and notebooks.
Another possibility that Bluetooth affords is the deconstruction of products into individual elements, enabling new form factors and unit kinds. For example, by having a separate headset there is no longer the need to include one in a cell phone, which simply becomes a cellular receiver/transmitter interacting with the cellular network, PDAs and laptops. More long-term, a so-called killer application for Bluetooth could well be access that is public. It’s all well to possess synchronization between the notebook, PDA or cellular phone but, whenever in an airport or mall, access to the online or details about the area that is local be valuable. For that to happen, though, there is the chicken and egg situation where a company will not deploy Bluetooth enabled access points unless you will find significant numbers of devices in the marketplace to utilize them and vice versa. Exactly the same is true of the providers associated with given information that users will be seeking. Nevertheless, this is an area earnestly being develop ed.
Public access is a application that is definite WLAN and, as has been mentioned, systems are already being globally deployed in airports. Their data that are high being comparable to the wired Ethernet makes them specially suitable for the enterprise sector for computer networking between PCs and to use the trend towards laptop mobility. Ease, low cost therefore the facility for expansion additionally make WLAN suitable for tiny workplace office at home (SoHo) execution as well as the expansion of the house broadband access market, particularly in the united states, also starts up possibilities.
THE 5 GHZ FREQUENCY BAND
Regardless if simply a small fraction of those applications for Bluetooth and WLAN visited fruition, the slim (80 GHz) 2.4 GHz band will soon be congested. In anticipation of the, spectrum will play a role that is crucial the deployment of next-generation, high speed WLANs and has prompted licensing authorities globally to allocate large blocks of license free spectrum in the 5 GHz band. A total of 455 MHz is available in the two blocks from 5.15 to 5.35 GHz and from 5.470 to 5.725 GHz as figure 7 shows, in Europe. Likewise, the US has allocated a total of 300 MHz within the two obstructs of range at 5.15 to 5.35 GHz and 5.725 to 5.825 GHz. In Japan, one 100 MHz block at 5.15 to 5.25 GHz will be considered.
Once again two different 5 GHz standards are being developed on either side for the Atlantic with both specifications offering information rates all the way to 54 Mbps, and for that reason well placed to deliver speed that is high services. Originating in the US the IEEE 802.11a standard was ratified in 1999. The physical layer (PHY) is based on orthogonal frequency division multiplexing (OFDM) and shares a common MAC layer with all IEEE 802.11 standards including 802.11b.
Instead the European Telecommunications guidelines institute (ETSI) is developing high performance radio LAN (HIPERLAN) standards as part of its Broadband broadcast Access Network (BRAN) initiative. Under its remit is the development of four criteria — HIPERLAN1, HIPERLAN2, HIPERLink (created for interior radio backbones) and HIPERAccess (designed for fixed exterior use to provide usage of a wired infrastructure).
The HIPERLAN1 standard, that is in line with the well-established means of Gaussian shift that is minimum (GMSK) modulation, is complete and was ratified in 1997. HIPERLink and HIPERAccess, on the other hand, are at the early stages of development. It is HIPERLAN2 where activity that is current focused.
The physical layers of both 802.11a and HIPERLAN2 use OFDM modulation to obtain high speed transmission rates. This multichannel spread spectrum modulation technique allows individual channels to maintain their distance (or orthogonality) to adjacent channels, enabling data symbols to be reliably extracted and multiple subchannels to overlap in the frequency domain for increased efficiency that is spectral. For example, within the range allocation for European countries, HIPERLAN2 channels are going to be spaced 20 MHz apart for a complete of 19 stations.
Both IEEE 802.11a and HIPERLAN2 specify an OFDM layer that is physical splits the information signal across 52 separate sub-carriers. 48 provide separate wireless pathways for synchronous information transfer, even though the staying four are employed as a reference to disregard frequency or phase changes for the signal during transmission and supply synchronization. Synchronization allows coherent (in-phase) demodulation. The two standards could have this similarity but vary above the physical layer with 802.11a generally viewed as simpler and less complex, while HIPERLAN2 is mote advanced (or complicated based on your point of view) with wider scope.
For HIPERLAN2, mobile terminals such as for example a laptop computer or handheld devices talk to access points. These access points must have overlapping coverage areas to provide continuous coverage. Coverage typically extends 30 m indoors and 150 m in unobstructed environments. By utilizing automatic frequency allocation (AFA) access points monitor the HIPERLAN radio channels around them and automatically select an unused channel. A mobile terminal, after association, will simply keep in touch with one AP at each time, but if it receives a better signal strength it can request to be connected to another. When a mobile terminal roams from the coverage area of one access point to another, it automatically initiates a handoff to the access point that is new. The APs involved in the handover ensure that established connections within the fresh air interface as well as security associations are transparently shifted from the old to the new. Security support includes both key negotiation, verification (conventions such as for example the netw ork access identifier (NAI) and X.509 can be utilized), along with encryption making use of DES or 3-DES.
OFDM modulation can supply transmission prices of 54 Mbps but this is often dynamically modified to a diminished rate through the use of different modulation schemes depending on the prevalent radio conditions. All traffic is transmitted on connections, bi-directional for unicast traffic and uni-directional towards the mobile terminals for broadcast and multicast traffic. This method makes support for quality of service (QoS), implemented through time slots, straightforward. QoS parameters include bandwidth, bit mistake rate, latency and jitter. The original request by a mobile terminal to send data uses specific time slots that are allocated for random access. The access point grants access by allocating time that is specific for a certain period in transport channels. The terminal that is mobile sends data without interruption from other mobile terminals operating on that frequency. A control channel provides feedback to the sender, indicating whether data was received in error and whether it must be retransmitted. The QoS de livered depends on how the HIPERLAN2 network interoperates with the network that is fixed as an example, in case it is via packet-based Ethernet, cell-based ATM or IP.
HIPERLAN2 operates as a extension that is seamless of networks, so wired network nodes see HIPERLAN2 nodes as other network nodes. All networking that is common at layer 3 (IP and IPX, for example) will run over HIPERLAN2, allowing all common network-based applications to work, making the technology both system and application independent. Interoperation with Ethernet systems is supported from the beginning, but extensions that are easy provide support for ATM, PPP, IP and UMTS. The standard has been specified with the objective that is clear of interoperability plus the industry consortium, HIPERLAN2 Global Forum (H2GF), aims to run tests to confirm interoperability among items from member organizations.
The absolute most obvious application for HIPERLAN2 will be in the enterprise LAN environment but networks can also be deployed at ‘hot spot’ areas such as airports and hotels, supplying remote access and Internet services to business people. Its ability to act as an alternative access technology to 3G cellular networks is also a key application. As the high throughput and QoS features of HIPERLAN2 support the transmission of video streams in conjunction with datacom applications, HiperLAN2 has potential applications in the home by creating a wireless infrastructure for home devices (for connecting home PCs, VCRs, cameras and printers, for example).
HIPERLAN2 almost sounds too good to be true and price-to-market is an issue. For example, the higher cost of silicon for OFDM operation could stall reasonably priced execution. At the moment, expenses stay relatively high for 5 GHz OFDM systems, due mainly to the linearity that is high that it places on the power amplifier in the transmitter and the low noise amplifier in the receiver. Consequently, HIPERLAN2 products will likely cost more than lower speed alternatives. Also, some view the fact that HIPERLAN2 is sophisticated and able to support a wide range of applications not necessarily as a selling point but as overkill that comes at a high price.
On the other hand, IEEE 802.lla, because of its simplicity and maturity, represents lower costs and a faster time-to-market. However, although 802.1la and HIPERLAN2 have a near identical layer that is physical they differ within the MAC layer. Deficiencies include integral quality of service, guaranteeing performance in work environments when home video that is streaming. Therefore, efforts to close the MAC gap are a priority. Moreover, whereas the IEEE 802.lla and HIPERLAN2 both meet US regulatory spectrum requirements, HIPERLAN2 is currently the sole 5 GHz WLAN that meets European disturbance avoidance restrictions. Conversely, HIPERLAN2 must limit the regularity power and range for the united states to comply with FCC rules.
The danger is apparent with all the possibility that the united states and European countries will embrace two different standards. The consequence that the corporates’ inability to use one standard and benefit from lower acquisition and support costs could delay deployment of 5GHz LANs that is wireless significantly. It’s a serious issue for global development because they are two incompatible WLAN standards. Thus, if 802.lla and HIPERLAN2 wireless terminals were operating in the area that is same there would be interference, no coexistence with no interworking. Also, no roaming will be possible if different access points had been implemented in numerous public areas. The end user will have to make a standards option as well as the 5 GHz WLAN market is in danger of being fragmented if different industry players adopt different standards.
In order to avoid this several industry partners have begun a 5 GHz industry advisory group. In the HIPERLAN2 ETSI BRAN group and 802.lla Forum there are sub groups specifically taking a look at what exactly is needed to reach one standard. At present, there was much work to be achieved.
The short range wireless data networking headlines have been dominated by Bluetooth, resulting in unreasonably high expectations over the last few years. What tends to be forgotten is that, in relation to the development of similar technologies, Bluetooth is still embryonic. It is also a victim of its own potential. Articles on the subject wax lyrical about the possibility of consumer appliances being Bluetooth-enabled to have the capacity to ‘talk’ to each other and the merits of so-called ‘hidden computing’ applications. These will allow synchronization of laptops, PDAs and phones that are mobile automatically update calendars, appointments and e-mail whenever within range. Envisaged commercial applications range from the monitoring that is wireless of goods and chemical procedures.
But, most of the applications that are early essentially cable replacement or connection substitutes primarily aimed at the cell phone and FDA markets. The industry needs to walk before it can run so it should be, and to a great extent is, concentrating on steady development and addressing ways of ensuring interoperability, standardization and coexistence issues. Bluetooth has its origins in Europe having its initial development concentrated in Scandinavia, and even though its undoubtedly a technology that is global that is where its early deployment will be greatest. Bluetooth has attracted all the players that are key investment is considerable and maybe a few of the buzz is justified.
The IEEE 802.llb (WiFi) WLAN standard has been developed steadily without any razzmatazz on the other side of the coin and the Atlantic, but in the same 2.4 GHz unlicensed frequency band. Its high data rate, together with the falling costs of PC cards, allied to the mobility and flexibility it offers has seen market growth that is significant. It’s in a position to take advantage of the rise within the usage of laptops and development in house broadband access. Globally, 802.1lb networks are making inroads in ‘hot spot’ applications at airports, conference facilities and accommodations, and WiFi items are striking the market. Once again, problems of interoperability, coexistence and standardization are being addressed. However, although the establishment of a test that is registered in European countries will assist acceptance, official certification has to be more widespread.
With all the inevitability that the unlicensed 2.4 GHz band will end up congested, the development of the 5 GHz band for next generation speed that is high is vital. However, the possibility of fragmentation, with separate standards being adopted in the US and Europe is a threat that is real worldwide development and might postpone implementation significantly. A standards war will benefit no one, possibly undermining confidence and making manufacturers cautious about significant investment.
Going wireless has come with some strings connected but short range wireless systems have actually a long term future. Its ability to satisfy the industry’s desire for seamless connectivity will ensure market that is continued and development.
The author wish to thank the individuals that are following companies for their aid in compiling this supplement:
* Mobilian Corporation, www.mobilian.com
* Vincent Vermeer, company development supervisor — Wireless Connectivity Division, 3COM (Europe), www.3com.com
* Dr Jamshid Khun Jush, chairman of ETSI BRAN and specialist that is senior LANs at Ericsson, www.ericsson.com
* Martin Johnsson, president HIPERLAN2 Global Forum and WLAN item supervisor at Ericsson, www.ericsson.com/wlan
* Peter Bates, VP company development, www.bluesocket.com
* Andy Craigen, senior manager, Wireless Terminals Applications, Agere techniques
* Bob Heile, chairman IEEE 802.15 Working Team
* The organizers and speakers at the LAN that is wireless conference London in April 2001. Organized by EF-Telecoms, www.ef-international.co.uk
* Frost & Sullivan, www.frost.com
* Figure 2 and Figure 3 are taken with authorization from presentations available on www.ieee802.org/15/ EUROPEAN 3G SPECTRUM AT [greater than]$700 M PER MHz COST $B GERMANY 47.5 UK 32.9 ITALY 11.4 FRANCE 9.3 Note: Table made from bar graph