The growth of short range wireless systems, specially Bluetooth and wireless area that is local (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 special supplement Microwave Journal reviews current European activity, worldwide expansion and globally competing technologies to discover whether going wireless comes with strings connected.
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 currently required to connect a PC, not only to your community, but additionally to its peripherals such as for example the keyboard, mouse and printer. Meanwhile, the flexibility of cellular and cordless technology has promoted a few ideas for a generic short range wireless access solution for different products.
They are all desirable aims but the fascination with and development of brief range wireless data networking have not simply been prompted by the requirement to office that is disentangle from trailing wires. The real impetus has originate from the desire and expectation of people and companies in order to get into data and information almost anytime, anywhere, anyplace. 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 market that is untapped 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 built 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 deployment that is global is regarded as both a competing technology and growth market in its right.
BLUETOOTH: AN OVERVIEW
Since Ericsson originally devised the technology in 1994 Bluetooth has grabbed the imagination and most of the headlines. The business proceeded 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 purpose that is main of SIG is protect the integrity associated with technology and control its development. Its responsible for the certification procedure that all devices must complete before they can be acknowledged as having a Bluetooth compliant product. Without certification, a product cannot claim to be Bluetooth-enabled or use the Bluetooth trademark. The certification procedure ensures that designers stick to the standard and guarantee interoperability.
The commercial specification, 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 is named after a century that is 10th King — Bluetooth has inevitably become of worldwide interest to both manufacturers and prospective users.
The attraction is that Bluetooth could offer low cost, 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, along with help for real-time traffic of both vocals and information, allow it to be an attractive wireless technology that is networking personal digital assistants (PDA), cell phones and laptop computers.
Licensed range is high priced, particularly in European countries ([greater than] $100 billion paid for 140 MHz). A major appeal of Bluetooth is it runs at the internationally available unlicensed industrial, clinical and medical (ISM) 2.4 GHz frequency musical organization, allowing compatibility that is worldwide. Figure 1 shows the european spectrum that is 3G 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 as much as seven servant devices are set to communicate with a master radio in a single unit. As Figure 3 illustrates, several of these piconets could be founded and connected together in advertising hoc scatternets to allow communication among continually configurations that are flexible. All devices in the same piconet have priority synchronization, but other products can be 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 strategy, under which voice packets should never be retransmitted. The master device controls the web link bandwidth and decides how much bandwidth to share with each slave and slaves should be polled before transmission.
An asynchronous channel that transmits data can support an asymmetric link of 721 kbps in either direction and permit 57.6 kbps in return. The channel can support 432.6 kbps for a symmetric link. Since Bluetooth devices can help three vocals stations running at 64 kbps, or one data channel, they can achieve information prices of up to 1Mbps. The Bluetooth 1.0 specification calls for 1 mW transmitters with a nominal antenna power of 0 dBm to operate up to 10 m (type of sight). A greater energy transmitter of 100 mW (+20 dBm) included in the specification increases the number to 100 m, even though this will require a separate PA antenna driver. The compromise is increased costs and energy usage.
Bluetooth makes use of regularity hopping spread spectrum (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. Every 1.28 seconds 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. The text starts when one device initiates an association and becomes the master associated with the piconet. A connection is made by a full 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 then connect. At the point of connection each device assumes a media access control (MAC) address to distinguish them.
The Bluetooth technical specification may 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 half that is first of year because of the end of 2001 seeing significant predictions.
Frost & Sullivan forecasts global shipments of Bluetooth-enabled items to achieve over 11 million units in 2001, equaling $2.5 billion in revenues, while Micrologic Research is more conservative featuring its estimation that the market will 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 embryonic technology this is perhaps understandable.
This is certainly a 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 even the most progressive designers were not attracted to the project until 1998. Other mobile communications technologies such as for example the GSM took longer to develop than will be allowed for Bluetooth.”
Semiconductor chipset development is an integral element in the technology’s progress, with a selection of development designs rising within the Bluetooth semiconductor industry. Two manufacturing that is distinct are increasingly being taken. There are either those offering complete integrated solutions from the silicon wafer level to the consumer product degree or those part that is providing of sum of a chipset, that is, baseband, radio and pc software.
Debate continues over probably the 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 becomes increasingly important as semiconductor companies come closer to starting their products on the market.
Alongside some of the big names a number of smaller design services companies have entered the Bluetooth software market offering complete or partial protocol stacks to semiconductor developers. 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 bigger built-in Bluetooth developers, Philips Semiconductors happens to be the player that is main offer solutions in volume. It is expected that a large number of solutions are going to be on offer by the end of 2001.
Market success can be dependant on a chicken and egg 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 revenue that is future for chipset companies. Despite such terms of care Frost & Sullivan forecasts that the sum total shipments of Bluetooth chipsets would 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 offerings that are bluetooth fairly generic wireless community access items, such as Computer cards and other add-on products, along with access points (AP).
Also, in European countries, a significant number of Bluetooth 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 in the telecoms currency markets plus the gear necessary to roll-out Universal Mobile Telecommunication System (UMTS) companies hasn’t yet arrive at fruition, most of the services prepared for 3G mobile could possibly be delivered by available technologies which operate in unlicensed (free) frequency bands.
Mobile operators who’ve 3G permit debts to service are under great pressure to maximize revenue of current data solutions, and demonstrate that the market has got the appetite for 2.5G and 3G services. 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, as an example, 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 appearing from the wings as a contender that is strong 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 a wireless user interface card that is either part of the wireless device or connected to it. The technology is in no way a newcomer, however. In fact, it was back in 1990 when, in the US, the IEEE 802.11 Wireless geographic area Networks guidelines performing Group was formed using the task of developing a global standard for radio gear and companies operating into the 2.4GHz unlicensed regularity band for information rates of 1 and 2 Mbps.
Over 10 years ago what the first 802.11 standard did, to a degree, had been to simply help unify a confused WLAN marketplace, that was crowded with proprietary solutions. Although the original specification supported 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 was adopted in 1997. The modulation scheme used when running during the 1 Mbps rate is binary phase shift 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. 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 with this technique. Nonetheless, these data rates of 1 Mbps and 2 Mbps are considerably slow compared to wired LAN equivalents. This aligned with concerns over interperability and price, limited take up and acceptance for the standard as a viable option.
That all changed in September 1999 when the IEEE ratified a fresh rate that is high 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 all of them must share 11 Mbps of capability. There might be three access points involved in the same area, and each typically has an indoor range of 90 m at 1 Mbps and 25 m at 11 Mbps. To achieve this higher data rate the IEEE 802.11 b specifies complementary code keying (CCK) as the modulation scheme. The technique maps four bits per icon to achieve 8 Mbps, which allied to a heightened rate of 1.375 Msps yields a bit rate of 11 Mbps. Consequently, even though the 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 dropping back once again to 1 Mbps or 2 Mbps procedure.
With a business human body to verify interoperability and also the interoperability of 802.11b cards being assured, as a result of there being simply two silicon manufacturers worldwide making use of a MAC that is similar layer, 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 led to a renewed curiosity about, and perhaps more importantly, investment in the development of 802.11b products by big players whom would not view any participation in 1 to 2 Mbps items as a option that is viable.
Now, the huge benefits that WLANs offer with regards to flexibility and flexibility, allied to increased speed together with dropping costs of Computer cards, has managed to get an attractive option for 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 directly exchange data. Instead, an access point allows PCs to keep in touch with fixed Ethernet topologies via an Ethernet hub or switch port. Although WLAN cards are still far more expensive than ordinary cable-based Ethernet cards, having a standard means that all manufacturers move to the same technology and prices come down. Today there are cards at around the $200 mark.
The key to 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 802.llb networks, with resort hotels and seminar facilities also being prime regions of development. Furthermore, aided by the increased utilization 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 workplace, at home as well as on their travels and never having to swap cards. Only a deployment that is wide of will facilitate that.
Mobile operators also see WLANs as an affordable and easy way to 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 usage. Once more, at CeBit there were numerous gear providers showing WiFi elements by means of Computer 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 test that is european become recognized quickly. Such expansion is a must for the technology to be viewed as truly worldwide regarding development.
The key factor in the development and development of this WLAN market has been the increased data rate of 11 Mbps being afforded by the 802.llb standard. 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 frequency band that is 2.4GHz. The expectation is the information rates are risen to higher than 20 Mbps as well as the mission associated with task group is always to review proposals. Aspects of development currently being undertaken which could afford this ‘doubled’ data rate include a new modulation technology that improves the robustness of RF information transmissions. It not only overcomes a lot of the background RF sound and other sources of disturbance but in addition offers better performance against multipath interference.
On the receiver part, 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 unrecoverable corruption of a reflected information stream or loud signals are discarded and therefore are retransmitted which slows the info rate and interrupts the data movement, the system is less reliable for realtime transmission. With advanced equalizer technologies, reflected or signals that are noisy not simply discarded or filtered out. Forward mistake correction (FEC) algorithms may take corrupted signals and reconstruct them, dramatically reducing retransmits.
Data rates of over 20 Mbps will start new applications for the industry to exploit. As might be expected, interest shall most likely be light emitting diode by leisure applications. Quicker 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 could be a way off nevertheless 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. 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 in the coming years. Inspite of the outlook that is optimistic the entire market, particularly in the US, Western Europe and Japan, IDC believes vendors will have to over come several hurdles, including resolving standardization dilemmas, educating their partners, improving safety and reducing costs to ensure WLANs are affordable for conventional sections.
The chipset market for 2.4 GHz WLAN products is placed to keep to grow, although development shall not be as high as for Bluetooth chipsets. Frost & Sullivan anticipates direct sequence 802.11b Chipsets to be in great demand, predicting that the market for them shall be worth over $1.3 billion in 2006. This demand shall be driven by the growth in mobile computing and by dropping item costs.
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 is now a fear of the unknown. What is known is interference between 802.1 lb and devices that are bluetooth occur. In the US the Federal Communications Commission (FCC) requires every device operating in unlicensed bands to have a label stating that it can cause interference. However, what’s not known is the potential of this problem. The fact the devices run in an unlicensed band and projections of mushrooming market growth for Bluetooth and 802.1lb is fueling concerns.
Even though amount of concern may turn down to be unwarranted, this has at the very least grabbed the interest of wireless criteria groups, regulatory figures and industry that is wireless. They are all well aware that if users do experience interference problems it will 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 performed and standards are being addressed to limit disturbance. 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, extensive research observe the consequence that WiFi and Bluetooth devices operating in the same vicinity have actually using one another is under method. Results do vary and Figures 4 and 5 are types of a study that is particular 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 two antennas within a meter, but, and there may be interference that is significant.
Interference really becomes a serious issue when 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 role that is important products such as notebook PCs. An illustration is a notebook who has a Bluetooth radio integrated for link with a PDA or cell phone and at exactly 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, together with industry partners, is a business working on developing a remedy 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 rapid time-to-market approach which gives a single-card guide design just. The close proximity of the two radios with no coexistence mechanism will likely produce worst-case situations, and certainly will consequently result in significant degradation to both radios’ performance.
Dual-mode radio switching will not require changes to your silicon, and could be reasonably quick to advertise. It incorporates a coexistence apparatus that needs that while one radio is functional, the other is totally suspended. The procedure can primarily be implemented in two ways. In the first, the system simply shuts the radio that is non-operating with no signaling to many other nodes in its network. This could easily lead to problems for the system and certainly will drop performance levels below that of simple ‘collocation without a coexistence system.’ 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 nature that is modal on/one off), but is a lot better than simply shutting the radios down. Neither method supports switching while Bluetooth voice (SCO) links are in procedure.
Driver-level transmit switching generally describes an approach by which application transmit demands are mediated at the driver degree, thereby avoiding transmission that is simultaneous. Intuitively, this approach degrades throughput by some measure simply due to its modal transmit framework. More crucial, though, are its restrictions to avoid collisions with incoming packets. The resulting transmission of one protocol during reception of this other causes loss of gotten 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 reaction time (non-real-time). Once again, this approach will not switch quickly sufficient to guide Bluetooth SCO links, and will also have problems mitigating the disturbance from Bluetooth piconet master/slave polling activities.
While Bluetooth adaptive hopping definitely improves performance that is simultaneous 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 method’s effectiveness is compromised with higher penetrations of WiFi systems and unmodified Bluetooth devices. Adaptive hopping will likely be initiated as an Bluetooth that is optional profile indicating that modified products will maybe not utilize the functionality in piconets with unmodified products. Further, into the existence greater than one Bluetooth piconet or WiFi system, adaptive hopping is counter productive to coexistence.
MAC-level switching is the most effective associated with modal/switching style approaches, and provides performance levels approaching those in no-interference scenarios. It is a collaborative technique accomplished by exchanging information between the two protocols during the MAC level and managing transmit/receive operations properly. Because MAC-level switching is carried out in the baseband, with the ability to switch between protocols at a much faster rate than driver-level approaches. Consequently, with the ability to mitigate lots of the problems that driver-level cannot that is switching. MAC-level switching does not suffer from transmitting signals into incoming receptions, Bluetooth polling or system that is operating. But, its 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 offers the power to immediately identify all available networks that are wireless select the ones needed and connect to them seamlessly. By providing coexistence in a highly integrated solution that is two-chip an analog front-end chip and an electronic digital baseband chip – it allows simultaneous procedure of this two protocols while eliminating disturbance and maintaining dependability and performance. Interference is a genuine concern and, 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 could be competing within the frequency that is same 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 personal devices there may also be the need for Bluetooth radios to be included in access points and notebooks.
Another possibility that Bluetooth affords is the deconstruction of products into specific components, allowing for brand new kind factors and device types. For instance, 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 public access. It’s all well to own synchronization between your notebook, PDA or mobile phone but, when in an airport or retail center, usage of the Internet or information about the local area would be valuable. For that to happen, though, there is the chicken and egg situation where a company is not going to deploy Bluetooth enabled access points unless you can find significant amounts of devices available on the market to use them and vice versa. The same is true of the providers for the information that users will be seeking. Nevertheless, this is an certain area actively 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 high data rate being comparable to the wired Ethernet makes them especially appropriate the enterprise sector for computer networking between PCs and also to make use of the trend towards laptop flexibility. Simpleness, low cost plus the center for expansion also make WLAN ideal for small office home office (SoHo) execution as well as the expansion of the property broadband access market, particularly in the united states, also starts up opportunities.
THE 5 FREQUENCY that is GHZ BAND
Regardless if simply a fraction of these applications for Bluetooth and WLAN come to fruition, the slim (80 GHz) 2.4 GHz musical organization will soon be congested. In expectation 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. As Figure 7 shows, in Europe, 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. Likewise, the united states has allocated a complete of 300 MHz in the two obstructs of spectrum 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 has been considered.
Again two different 5 GHz criteria are being developed on either part associated with Atlantic with both specs providing information prices as high as 54 Mbps, and for that reason well placed to give 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 802.11b that is including.
Instead the European Telecommunications Standards institute (ETSI) is developing performance that is high LAN (HIPERLAN) standards as part of its Broadband broadcast Access Network (BRAN) initiative. Under its remit is the growth of four standards — HIPERLAN1, HIPERLAN2, HIPERLink (created for indoor radio backbones) and HIPERAccess (intended for fixed Outdoor use to provide usage of a wired infrastructure).
The HIPERLAN1 standard, which is on the basis of 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 concentrated.
The physical layers of both 802.11a and HIPERLAN2 use OFDM modulation to reach speed that is high 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. As an example, in the range allocation for Europe, HIPERLAN2 channels is going to be spaced 20 MHz apart for an overall total of 19 channels.
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 data transfer, as the staying four are used as a reference to disregard frequency or phase shifts of this signal during transmission and offer synchronization. Synchronization allows coherent (in-phase) demodulation. The 2 criteria may have this similarity but differ over the layer that is physical 802.11a generally speaking viewed as simpler and less complex, while HIPERLAN2 is mote advanced (or complicated according to your viewpoint) with wider scope.
For HIPERLAN2, mobile terminals such as for instance a laptop computer or handheld products keep in touch with access points. To provide continuous coverage, these access points must have overlapping coverage areas. 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 channel that is unused. A mobile terminal, after association, will only communicate with one AP at each and every stage, 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 taking part in the handover ensure that established connections over the air interface as well as security associations are transparently shifted from the old to the new. Security support includes both key negotiation, authentication (conventions such as the netw ork access identifier (NAI) and X.509 may be used), along with encryption using DES or 3-DES.
OFDM modulation can supply transmission rates of 54 Mbps but this is often dynamically adjusted to a diminished rate by making 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 help for quality of service (QoS), implemented through time slots, straightforward. QoS parameters include bandwidth, bit error rate, latency and jitter. The request that is original 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 particular duration in transportation 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 fixed network; for example, when it is via packet-based Ethernet, cell-based ATM or internet protocol address.
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 (internet protocol address and IPX, as an example) will run over HIPERLAN2, allowing all typical network-based applications to use, 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 clear objective of achieving interoperability plus the industry consortium, HIPERLAN2 Global Forum (H2GF), aims to perform tests to validate interoperability among products from member businesses.
Probably the most application that is obvious 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 application that is key. 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) as the high throughput and QoS features of HIPERLAN2 support.
HIPERLAN2 almost appears too good to be real and price-to-market is a concern. For instance, the bigger price of silicon for OFDM operation could stall reasonably priced implementation. At present, expenses stay relatively high for 5 GHz OFDM systems, due primarily to the high linearity demands 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 range that is wide of certainly not as a selling point but as overkill that comes at a price.
In the other hand, IEEE 802.lla, due to its simplicity and maturity, represents lower costs and a faster time-to-market. However, although 802.1la and HIPERLAN2 have a near identical physical layer, they differ into the MAC layer. Inadequacies include integrated quality of service, guaranteeing performance in work environments when streaming home video. 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 the only 5 GHz WLAN that satisfies European interference avoidance limitations. Conversely, HIPERLAN2 must limit the regularity power and range for the US to adhere to FCC rules.
The danger is obvious aided by the possibility that the united states and Europe will embrace two standards that are different. 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 is a issue that is serious global development because they are two incompatible WLAN standards. Thus, if 802.lla and HIPERLAN2 wireless terminals were operating in the same area, there would be interference, no coexistence and no interworking. Also, no roaming is feasible if different access points were deployed in various areas that are public. The end user will be required to make a standards option as well as the 5 GHz WLAN market is vulnerable to being fragmented if different industry players follow different standards.
To avoid this a few industry partners have started a 5 GHz industry advisory group. In the HIPERLAN2 ETSI BRAN 802.lla and group Forum there are sub groups particularly taking a look at what is required to arrive at one standard. At present, there is certainly work that is much be done.
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 upgrade calendars, appointments and email whenever within range. Envisaged commercial applications are the monitoring that is wireless of goods and chemical processes.
However, the majority 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 global technology, that is where its early deployment will be greatest. Bluetooth has attracted all the players that are key investment is considerable and maybe some of the hype 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 significant market growth. It is in a position to enjoy the rise within the usage of laptop computers and development in home broadband access. Globally, 802.1lb systems are making inroads in ‘hot spot’ applications at airports, seminar facilities and hotels, and WiFi items are striking the marketplace. Once again, dilemmas of interoperability, coexistence and standardization are being addressed. However, although the establishment of a test that is registered in European countries will aid acceptance, certification has to be much more widespread.
Because of the inevitability that the unlicensed 2.4 GHz musical organization will end up congested, the development of the 5 GHz band for next generation high speed WLANs 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 may delay deployment dramatically. A standards war will gain nobody, perhaps undermining self-confidence and making manufacturers cautious about significant investment.
Going wireless has include some strings connected but short range wireless systems have actually a term future that is long. Its ability to satisfy the industry’s desire for seamless connectivity will ensure continued market growth and development.
Mcdougal want to thank the following individuals and companies for their aid in compiling this health supplement:
* Mobilian Corporation, www.mobilian.com
* Vincent Vermeer, company development manager — 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 manager 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 Group
* The organizers and speakers during the Wireless LAN conference in 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 permission 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