The growth of short range wireless systems, specially 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 businesses. In this special supplement Microwave Journal reviews current European activity, worldwide expansion and globally competing technologies to discover 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 currently necessary to connect a PC, not only to the system, but additionally to its peripherals such as for example the keyboard, mouse and printer. Meanwhile, the flexibility of cellular and technology that is cordless promoted ideas for a generic short range wireless access solution for various devices.
These are all desirable aims however the interest in and development of quick range wireless information networking hasn’t just been prompted by the requirement to disentangle office chairs from trailing wires. The impetus that is real result from the desire and expectation of an individual and companies to be able to gain access to data and information 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 market that is lucrative assured provided that the technology can be obtained 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 contenders that are leading Bluetooth and WLANs. Issues covered add how Bluetooth has built on its European origins and development that is early 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 considered as both a competing technology and development market in its right.
BLUETOOTH: A SYNOPSIS
Since Ericsson originally devised the technology in 1994 Bluetooth has grabbed the imagination & most for the headlines. The organization proceeded working on 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 for the technology and control its development. Its accountable for the certification process that all devices must complete before they can be known as having a Bluetooth compliant product. Without certification, a product cannot claim to be Bluetooth-enabled or utilize the Bluetooth trademark. The official certification procedure means that designers stick to the standard and guarantee 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 with this specification. From its European origins — it really is named after a 10th century Norwegian King — Bluetooth has inevitably become of global interest to both manufacturers and possible users.
The attraction is the fact that Bluetooth could possibly 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 high transmission rates. These features, together with help for real-time traffic of both sound and information, allow it to be an attractive wireless networking technology for individual digital assistants (PDA), cell phones and laptop computers.
Licensed spectrum is high priced, especially in European countries ([greater than] $100 billion covered 140 MHz). An important selling point of Bluetooth is the fact that it runs at the internationally available unlicensed industrial, systematic and medical (ISM) 2.4 GHz frequency band, enabling 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 in 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 current specification, up to seven slave products could be set to communicate with a master radio in one single unit. As Figure 3 illustrates, several of these piconets could be founded and linked together in advertisement hoc scatternets allowing communication among continually configurations that are flexible. All devices in the same piconet have priority synchronization, but other devices may 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 technique, under which voice packets are never retransmitted. The master unit controls the hyperlink bandwidth and chooses how much bandwidth to give to 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. The channel can support 432.6 kbps for a symmetric link. Since Bluetooth devices can support three vocals channels operating at 64 kbps, or one data channel, they could attain information prices of up to 1Mbps. The Bluetooth 1.0 specification requires 1 mW transmitters with a nominal antenna power of 0 dBm to operate as much as 10 m (type of sight). An increased power transmitter of 100 mW (+20 dBm) contained in the specification will increase the product range to 100 m, even though this will require a separate PA antenna motorist. The compromise is increased costs and power usage.
Bluetooth makes use of 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. 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 bond begins when one device initiates a connection and becomes the master of this piconet. An association is manufactured by a typical 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. 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 12 months because of the end of 2001 seeing significant predictions.
Frost & Sullivan forecasts worldwide deliveries of Bluetooth-enabled items to reach over 11 million devices in 2001, equaling $2.5 billion in revenues, while Micrologic analysis is more conservative having 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 maybe understandable.
This 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 even the most progressive designers are not attracted to the project until 1998. Other mobile communications technologies such as for instance the GSM took longer to produce than is being allowed for Bluetooth.”
Semiconductor chipset development is a key aspect in the technology’s progress, with a variety of development designs rising within the Bluetooth semiconductor industry. Two manufacturing that is distinct are being taken. There are either those offering complete integrated solutions from the silicon wafer degree towards the consumer item degree or those part that is providing of sum of a chipset, that is, baseband, radio and 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 will become increasingly crucial as semiconductor companies come nearer to releasing their products or services 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. Amongst the larger integrated Bluetooth designers, Philips Semiconductors is the main player to offer solutions in volume. It is expected that a number that is large of will soon be on offer by the conclusion of 2001.
Market success are determined by 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 future revenue streams for chipset companies. Despite such words of caution Frost & Sullivan forecasts that the total shipments of Bluetooth chipsets will 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 network access items, such as PC cards as well as other add-on products, as well as access points (AP).
Also, 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 cost that is huge of licenses is impacting in the telecoms currency markets plus the gear necessary to roll-out Universal Mobile Telecommunication System (UMTS) systems has not yet come to fruition, lots of the solutions prepared for 3G mobile may be delivered by currently available technologies which operate in unlicensed (free) frequency bands.
Mobile operators who have 3G permit debts to service are under some pressure to maximise revenue of current data services, and indicate that the market has 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 gateway that is wireless. 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 public eye.
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 part of the wireless unit or plugged into 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 Local Area Networks Standards performing Team had been formed utilizing the task of developing a standard that is global radio equipment and systems running in the 2.4GHz unlicensed frequency musical organization for data prices of just one and 2 Mbps.
Over a decade ago what the original 802.11 standard did, to a diploma, had been to help unify a confused WLAN marketplace, that was crowded with proprietary solutions. Even though 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 harder that is signal intercept than standard wired Ethernet.
The IEEE 802.11 standard had been adopted in 1997. The modulation scheme used when 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. 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. But, these information rates of 1 Mbps and 2 Mbps are considerably slower compared to the wired LAN equivalents. This aligned with concerns over interperability and price, restricted use up and acceptance of this standard as a viable option.
That most changed in September 1999 once the IEEE ratified a new rate that is high for WLANs – IEEE 802.11b, which also goes under the various guises of WiFi (Wireless Fidelity) and high rate wireless Ethernet. It is significant because it offers a data that is top-end of 11 Mbps. Each access point can support a large number of connections, although they all must share 11 Mbps of capacity. There can be three access points working in the area that is same 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 sign to reach 8 Mbps, which allied to an elevated rate of 1.375 Msps yields a bit rate of 11 Mbps. Consequently, whilst 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 products by falling back once again to 1 Mbps or 2 Mbps procedure.
With a business human anatomy to verify interoperability while 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 Ethernet that is standard for. This has led to a renewed curiosity about, as well as perhaps more importantly, investment into the development of 802.11b items by big players who didn’t see any involvement in 1 to 2 Mbps products as a option that is viable.
Now, the benefits that WLANs offer with regards to mobility and flexibility, allied to increased speed and the 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. Alternatively, an access point allows PCs to talk to fixed Ethernet topologies via an Ethernet hub or switch port. Although WLAN cards remain much 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.
long range router DEPLOYMENT
The key to the progress of WiFi is its wide and deployment that is global 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 facilities also being prime aspects of development. Also, utilizing 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 without having to swap cards. Only a deployment that is wide of will facilitate that.
Mobile operators also see WLANs as a cheap 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 a large number of gear vendors 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 to be recognized soon. Such expansion is crucial for the technology to truly be viewed as international with regards to development.
The main element aspect in the growth and development associated with the WLAN market has been the increased information 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 will soon be risen to higher than 20 Mbps while the mission for the task group is always to review proposals. Aspects of development increasingly being undertaken which could afford this ‘doubled’ information rate include a modulation that is new that improves the robustness of RF data transmissions. It not only overcomes much of the backdrop RF noise and other sources of interference but additionally offers better performance against multipath disturbance.
On the receiver part, advanced equalizer technology used 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 loud signals are discarded and are retransmitted which slows the data rate and interrupts the information movement, the machine is less reliable for realtime transmission. With advanced equalizer technologies, reflected or noisy signals are not simply discarded or filtered out. Forward mistake modification (FEC) algorithms usually takes corrupted signals and reconstruct them, significantly reducing retransmits.
Data rates of over 20 Mbps will open up new applications for the industry to exploit. As might be expected, interest will probably be led by leisure applications. Faster transmission speeds will enable video that is streaming 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 conditioning and security systems.
THE WLAN MARKET
Such applications could be a way off however the WLAN is a growing market as 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 final 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. Inspite of the optimistic outlook for the general market, particularly in the US, Western Europe and Japan, IDC believes vendors will have to over come several hurdles, including resolving standardization issues, educating their partners, improving protection and reducing prices in order that WLANs are affordable for conventional portions.
The chipset market for 2.4 GHz WLAN products is set to keep to expand, although growth will 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 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 certain extent it has become a fear associated with unknown. What’s known is the fact that interference between 802.1 lb and devices that are bluetooth 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’s as yet not known is the potential of the issue. The fact the devices run in an band that is unlicensed projections of mushrooming market growth for Bluetooth and 802.1lb is fueling concerns.
Although the level of concern may turn out become unwarranted, it has at least grabbed the eye of wireless criteria groups, regulatory bodies and industry that is wireless. They are all well aware that if users do experience interference problems it shall damage user self-confidence in the technology. With so much investment it is a risk that manufacturers, in particular, cannot take. Global development that is technical is being carried out and standards are being addressed to restrict disturbance. 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 in the US.
Consequently, extensive research to monitor the result that WiFi and Bluetooth products operating in identical vicinity have on one another is under method. Results do vary and Figures 4 and 5 are types of a particular study to illustrate the effect. However, what is generally accepted is that then there will be graceful degradation of the two protocols, which will only be noticed by very sensitive users if the antennas of the Bluetooth and WiFi devices are kept over 2m apart. Go the 2 antennas within a meter, however, and there can be significant interference.
Interference actually 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 role that is important products such as for example notebook PCs. A good example is a notebook which has a Bluetooth radio integrated for link with a PDA or cell phone and at the same time has a WiFi radio integrated for LAN access.
Coexistence is a issue that is major 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 focusing on developing a solution and has 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 supplies a single-card guide design only. The close proximity of the two radios with no coexistence system will likely produce worst-case scenarios, and can consequently end in significant degradation to both radios’ performance.
Dual-mode radio switching does not require modifications towards the silicon, and may be relatively quick to market. It incorporates a coexistence apparatus that will require that while one radio is operational, one other is completely suspended. The operation can be implemented primarily 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 can lead to difficulties for the system and will drop performance levels below that of easy ‘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 just shutting the radios down. Neither method supports switching while Bluetooth voice (SCO) links are in procedure.
Driver-level transmit switching generally describes an approach in which application send demands are mediated at the motorist degree, thereby avoiding simultaneous transmission. Intuitively, this approach degrades throughput by some measure simply due to its transmit that is modal structure. More crucial, though, are its limitations in avoiding collisions with incoming packets. The ensuing transmission of one protocol during reception associated with other causes loss of received packets, interference and user that is potential. This is caused by the technique’s dependence on the host system that is operating which can be broadly speaking non-deterministic in its reaction time (non-real-time). Once more, this method will not switch quickly enough to support Bluetooth SCO links, and also will have difficulties mitigating the disturbance from Bluetooth piconet master/slave activities that are polling.
While Bluetooth adaptive hopping certainly 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 problem 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 optional Bluetooth profile, indicating that modified products will not utilize the functionality in piconets with unmodified devices. Further, in the presence of more than one piconet that is bluetooth WiFi system, adaptive hopping is counter effective to coexistence.
MAC-level switching is the most effective of the style that is modal/switching, and provides performance levels approaching those in no-interference scenarios. It is a technique that is collaborative by trading information involving the two protocols at the MAC level and managing transmit/receive operations consequently. Because MAC-level switching is performed into the baseband, it is able to switch between protocols at a much faster rate than driver-level approaches. Consequently, with the ability to mitigate most of the issues that driver-level cannot that is switching. MAC-level switching does not suffer from transmitting signals into incoming receptions, Bluetooth polling or operating system latency. But, it is susceptible to interference that is adjacent-channel does suffer noticeable degradation. Also, it has a longer development cycle than driver-level approaches because it is located in the baseband.
Simultaneous operation supplies the capacity to automatically identify 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 baseband chip – it allows simultaneous operation associated with the two protocols while eliminating interference and maintaining dependability 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 in 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 integrated in access points and notebooks.
Another possibility that Bluetooth affords is the deconstruction of devices into specific elements, permitting brand new form factors and unit types. For example, insurance firms 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 perfectly to own synchronization involving the notebook, PDA or cell phone but, when in an airport or mall, use of the online or details about the local area would be valuable. For that to happen, though, there is the chicken and egg situation where a ongoing company is not going to deploy Bluetooth enabled access points unless you can find significant numbers of devices available on the market to utilize them and vice versa. Exactly the same goes for the providers of the given information that users will be seeking. Nevertheless, this is an area earnestly being develop ed.
Public access is a definite application for 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 especially appropriate the enterprise sector for computer networking between PCs and also to take advantage of the trend towards laptop flexibility. Simplicity, low cost plus the center for expansion also make WLAN ideal for tiny workplace office at home (SoHo) execution therefore the expansion of the property broadband access market, especially in the US, also starts up opportunities.
THE 5 FREQUENCY that is GHZ BAND
Even though simply a fraction of the applications for Bluetooth and WLAN arrive at fruition, the narrow (80 GHz) 2.4 GHz band will soon be congested. In anticipation with this, 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 US has allocated an overall total of 300 MHz in the two blocks 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 is being considered.
Once again two different 5 GHz standards are now being developed on either part associated with Atlantic with both specifications offering information rates 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.
Alternatively the European Telecommunications Standards institute (ETSI) is developing high performance radio LAN (HIPERLAN) standards as an element of its Broadband broadcast Access system (BRAN) initiative. Under its remit is the development of four standards — HIPERLAN1, HIPERLAN2, HIPERLink (designed for indoor radio backbones) and HIPERAccess (designed for fixed exterior used to provide access to a wired infrastructure).
The HIPERLAN1 standard, which is in line with the well-established technique of Gaussian minimum shift keying (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 current activity is concentrated.
The physical layers of both 802.11a and HIPERLAN2 usage OFDM modulation to accomplish 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. As an example, within the spectrum allocation for Europe, HIPERLAN2 channels is going to be spaced 20 MHz apart for a total of 19 stations.
Both IEEE 802.11a and HIPERLAN2 specify an OFDM physical layer that splits the information signal across 52 separate sub-carriers. 48 provide separate pathways that are wireless synchronous information transfer, as the remaining four are used as a reference to disregard frequency or stage shifts for the signal during transmission and provide synchronization. Synchronization allows coherent (in-phase) demodulation. The 2 criteria may have this similarity but vary above the physical layer with 802.11a generally seen as easier and less complex, while HIPERLAN2 is mote sophisticated (or complicated depending on your point of view) with wider range.
For HIPERLAN2, mobile terminals such as for instance a laptop or handheld devices communicate 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 unused channel. A mobile terminal, after association, will simply keep in touch with one AP at each point in time, but it can request to be connected to another if it receives a better signal strength. 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 associated with 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 negotiation that is key verification (conventions such as for example the netw ork access identifier (NAI) and X.509 can be used), also encryption making use of DES or 3-DES.
OFDM modulation can provide transmission prices of 54 Mbps but this is dynamically modified to a lesser rate using modulation that is different 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 multicast and broadcast traffic. This method makes support for quality of service (QoS), implemented through time slots, direct. QoS parameters include bandwidth, bit mistake 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 specific time slots for a particular duration in transport channels. The mobile terminal then 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 internet protocol address.
HIPERLAN2 operates as a seamless extension of other networks, so wired network nodes see HIPERLAN2 nodes as other network nodes. All common networking protocols at layer 3 (internet protocol address and IPX, as an example) will run over HIPERLAN2, allowing all typical network-based applications to operate, making the technology both network and application separate. Interoperation with Ethernet networks is supported from the beginning, but easy extensions also provide support for ATM, PPP, IP and UMTS. The standard has been specified with the clear objective of achieving interoperability and also the industry consortium, HIPERLAN2 Global Forum (H2GF), aims to run tests to validate interoperability among items from member businesses.
Probably the 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 seems too good to be true and price-to-market is a concern. For example, the bigger price of silicon for OFDM operation could stall reasonably priced execution. At present, expenses remain fairly high for 5 GHz OFDM systems, mainly due 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 certainly not as a selling point but as overkill that comes at a price.
On 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 layer that is physical they differ in the MAC layer. Inadequacies include built-in quality of service, guaranteeing performance in work surroundings and 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 currently the actual only real 5 GHz WLAN that meets European disturbance avoidance restrictions. Conversely, HIPERLAN2 must limit the regularity power and range for the united states to conform to FCC rules.
The risk is apparent because of the possibility that the united states and Europe 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 wireless LANs notably. It really 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 possible if different access points were implemented in numerous areas that are public. The end user will be required to make a standards option as well as the 5 GHz WLAN market is in danger of being fragmented if different industry players follow different standards.
To avoid this a few industry partners have started a 5 GHz industry group that is advisory. In the HIPERLAN2 ETSI BRAN 802.lla and group Forum there are sub groups particularly considering what’s required to get to one standard. At present, there clearly was work that is much be achieved.
Over the last few years the short range wireless data networking headlines have been dominated by Bluetooth, resulting in unreasonably high expectations. 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 when within range. Envisaged industrial applications range from the wireless monitoring of transported goods and chemical procedures.
However, 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 European countries featuring its initial development concentrated in Scandinavia, and although it’s 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 perhaps a few of the buzz is justified.
On the other side of the coin and the Atlantic, but in the same 2.4 GHz unlicensed frequency band, the IEEE 802.llb (WiFi) WLAN standard has been developed steadily without any razzmatazz. 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 well placed to benefit from the rise in the usage of laptop computers and development in home broadband access. Globally, 802.1lb systems are making inroads in ‘hot spot’ applications at airports, meeting centers and resort hotels, and WiFi items are hitting the marketplace. Once more, problems of interoperability, standardization and coexistence are being addressed. However, although the establishment of a test that is registered in Europe will aid acceptance, certification needs to be much more widespread.
With all the inevitability that the unlicensed 2.4 GHz band will become congested, the growth associated with 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 global development and could delay deployment significantly. A standards war will benefit no body, perhaps undermining self-confidence and making manufacturers wary of significant investment.
Going wireless has include some strings connected but quick 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 businesses for his or her aid in compiling this supplement:
* Mobilian Corporation, www.mobilian.com
* Vincent Vermeer, business development manager — Wireless Connectivity Division, 3COM (European countries), www.3com.com
* Dr Jamshid Khun Jush, president 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 business development, www.bluesocket.com
* Andy Craigen, senior supervisor, Wireless Terminals Applications, Agere Systems
* 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 produced from bar graph