The development of short range wireless systems, especially 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 development and research driven by European-based organizations. In this supplement that is special Journal reviews current European activity, worldwide expansion and globally competing technologies to find out whether going wireless is sold with strings attached.
No wires — what an attractive proposition! Consider the savings in cabling costs and flexibility offered if an office’s computers were served by a WLAN. Just imagine being able to eliminate the tangled mass of wires presently necessary to connect a PC, not just towards the system, but in addition to its peripherals such as the keyboard, mouse and printer. Meanwhile, the mobility of mobile and technology that is cordless promoted some ideas for a generic short range wireless access solution for different products.
These are all desirable aims nevertheless the interest in and development of short range wireless information networking have not simply been prompted by the need to disentangle office chairs from trailing wires. The impetus that is real result from the desire and expectation of people and organizations to be able to gain access to data and information nearly 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 provided the technology is available to implement it.
With such a large and untapped market there has been no shortage of contenders vying to provide that technology. This article looks at two of the leading contenders, Bluetooth and WLANs. Issues covered add 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 unique right.
BLUETOOTH: AN OVERVIEW
Since Ericsson originally devised the technology in 1994 Bluetooth has grabbed the imagination and most of the headlines. The organization proceeded taking care of the project alone until February 1998, whenever it shared Nokia, Intel to its research, IBM and Toshiba to found the Bluetooth Special Interest Group (SIG). The main purpose of the SIG would be to protect the integrity of this technology and control its development. It’s accountable for the official certification procedure that most products must complete before they may be called having a bluetooth product that is compliant. Without official certification, a product cannot claim to be Bluetooth-enabled or use 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 products that are developing on this specification. From the European origins — it is called after a century that is 10th King — Bluetooth has inevitably become of global interest to both manufacturers and prospective users.
The attraction is that Bluetooth could offer cost that is low small physical size (single chip) and low power consumption over throughput and range. Allied to its capability to function in noisy radio environments and offer transmission that is high. These features, along with help for real-time traffic of both sound and data, make it an attractive wireless networking technology for individual digital assistants (PDA), mobile phones and laptop computers.
Licensed spectrum is high priced, particularly in Europe ([greater than] $100 billion paid for 140 MHz). A major benefit of Bluetooth is it runs at the internationally available unlicensed industrial, scientific and medical (ISM) 2.4 GHz frequency band, enabling worldwide compatibility. 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) at no cost. 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 device. As Figure 3 illustrates, several of these piconets could be founded and connected together in ad hoc scatternets allowing communication among constantly flexible configurations. All devices in the piconet that is same priority synchronization, but other devices are set to enter.
Bluetooth’s baseband technology supports both connection that is synchronous (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 sound packets should never be retransmitted. The master device controls the link bandwidth and chooses how bandwidth that is much give to each slave 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 voice stations operating at 64 kbps, or one information channel, they can achieve information prices of up to 1Mbps. The Bluetooth 1.0 specification calls for 1 mW transmitters with a antenna that is nominal of 0 dBm to operate as much as 10 m (line of sight). A greater power transmitter of 100 mW (+20 dBm) within the specification increases the number to 100 m, although this will demand a separate PA antenna driver. The compromise is increased expenses and power consumption.
Bluetooth utilizes frequency 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. Before any connections in a piconet are created, all devices are in standby mode which allows for the device to listen on 32 hop frequencies defined for each unit, for messages every 1.28 seconds. The connection begins when one device initiates a link and becomes the master associated with the piconet. An association is created by a page message then an inquiry message followed by a page message is sent if the address is known, and if it is not. The devices synchronize and connect then. 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 first half of this year because of the end of 2001 seeing significant predictions.
Frost & Sullivan forecasts worldwide shipments of Bluetooth-enabled items to achieve over 11 million devices in 2001, equaling $2.5 billion in revenues, while Micrologic Research is more conservative using 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 technology that is embryonic is possibly understandable.
This might be 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 original pioneers, perhaps the most progressive developers weren’t drawn to the project until 1998. Other mobile communications technologies such as the GSM took longer to produce than will be allowed for Bluetooth.”
Semiconductor chipset development is a vital take into account the technology’s progress, with a selection of development designs emerging in the semiconductor industry that is bluetooth. Two manufacturing that is distinct are being taken. There are either those offering complete integrated solutions through the silicon wafer degree towards the consumer item degree or those part that is providing of amount of a chipset, that is, baseband, radio and computer software.
Debate continues over many choice that is effective of 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 interoperability that is achieving will end up increasingly important as semiconductor companies come closer to releasing their products onto 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. An opportunity to build early market share with fast time-to-market solutions in the same vein Bluetooth has offered a number of smaller, highly innovative fabless semiconductor developers, such as Cambridge Silicon Radio and Silicon Wave. Between the bigger integrated Bluetooth designers, Philips Semiconductors has been the main player to offer solutions in volume. It is expected that a number that is large of is being offered by the end of 2001.
Market success can be based on a egg and chicken combination of chipset supply. Observers have warned that restrictions in the supply of chipsets to smaller product developers may cause delays in the time-to-market of new innovative applications that will provide revenue that is future for chipset providers. Despite such words of caution Frost & Sullivan forecasts that the sum total deliveries of Bluetooth chipsets will be over 956 million in 2006, while the market that is total 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 products, such as for instance Computer cards along with other add-on products, as well as access points (AP).
Additionally, in European countries, a number that is significant of mobile phones were launched at the CeBIT exhibition in Germany in March 2001 with many more expected over the summer. However, the market cocktail has become more intriguing because of 30 market developments. At a time when the cost that is huge of licenses is impacting in the telecoms stock exchange and also the equipment needed to roll-out Universal Mobile Telecommunication System (UMTS) companies hasn’t yet arrive at fruition, many of the solutions planned 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 some pressure to increase revenue of existing information solutions, and demonstrate that the market gets 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 a wireless interface card that is either part of the wireless unit or attached to it. The technology is in no real way a newcomer, however. In fact, it was back in 1990 when, in the US, the IEEE 802.11 Wireless geographic area Networks guidelines Working Team ended up being created aided by the task of developing a global standard for radio equipment and networks operating in the 2.4GHz unlicensed regularity musical organization for data rates of just one and 2 Mbps.
Over 10 years ago what the initial 802.11 standard did, to a diploma, had been to simply help unify a confused WLAN marketplace, that was crowded with proprietary solutions. Although the specification that is original three different transmission media — frequency hopping spread spectrum (FHSS), direct sequence spread spectrum (DSSS) and infrared (IR) — the major area of development has been for DSSS. DSSS spreads the signal over several frequencies, can switch channels to avoid interference and also makes the harder that is signal intercept than standard wired Ethernet.
The IEEE 802.11 standard was adopted in 1997. The modulation scheme used whenever running 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. However, these information prices of just one Mbps and 2 Mbps are considerably slow compared to wired LAN equivalents. This aligned with concerns over interperability and cost, limited take up and acceptance of this standard as a viable option.
That all changed in September 1999 when the IEEE ratified a fresh high rate standard for WLANs – IEEE 802.11b, which also goes under the various guises of long range router (Wireless Fidelity) and high rate wireless Ethernet. It is significant because it offers a top-end data rate of 11 Mbps. Each access point can support a large number of connections, although all of them must share 11 Mbps of capability. 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. The IEEE 802.11 b specifies complementary code keying (CCK) as the modulation scheme to achieve this higher data rate. The strategy maps four bits per icon to attain 8 Mbps, which allied to a heightened rate of 1.375 Msps yields a bit rate of 11 Mbps. Therefore, even though the true number of symbols sent per second hardly varies from the symbol rate used for IEEE 802.11 LANs, more hits per second are sent. Also, as CCK is a DSSS technique, 802.11 b is backward-compatible with products that meet the origin al 802.11 specification, enabling 802.11b standard products to interoperate with 802.11 compliant DSSS products by falling back into 1 Mbps or 2 Mbps procedure.
With a market human body to validate interoperability plus the interoperability of 802.11b cards being assured, because of there being just two silicon manufacturers worldwide utilizing 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 Ethernet that is standard for. This has led to a renewed desire for, and maybe more importantly, investment within the development of 802.11b items by big players whom did not view any involvement in 1 to 2 Mbps products as a viable option.
Now, the huge benefits that WLANs offer with regards to flexibility and flexibility, allied to increased speed as well as the falling costs of PC 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 exchange data directly. Instead, an access point allows PCs to keep in touch with fixed Ethernet topologies via an Ethernet hub or switch port. Although WLAN cards remain more expensive than ordinary cable-based Ethernet cards, having a means that is standard all manufacturers move to the same technology and prices come down. Today there are cards at around the $200 mark.
The important thing 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 additionally being prime aspects of development. Also, using the increased utilization of laptop computers, the synergy that is natural 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 office, in the home as well as on their travels and never have to swap cards. Just a wide deployment of 802.1lb will facilitate that.
Mobile operators additionally see WLANs as a cheap and way that is easy provide high speed access to densely populated areas. Because they rely on very short-range transmissions, users see improved battery life, and with health risks being a concern there is the advantage that is added of energy usage. Once again, at CeBit there have been numerous gear companies showing WiFi elements by means of Computer cards, universal serial bus (USB) devices, access points and home gateways. However, at present the Wireless Ethernet Compatibility Alliance (WECA) only recognizes one test house in the US for certification of WiFi products with plans for a European test house become recognized soon. Such expansion is essential for the technology to be viewed as truly international in terms of development.
The key factor in the development and development of the WLAN market is 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 that the information rates will soon be increased to higher than 20 Mbps and also the mission of this task group is always to review proposals. Aspects of development increasingly being undertaken which could afford this ‘doubled’ data rate add a modulation that is new that improves the robustness of RF data transmissions. It not just overcomes much of the background RF noise and other resources of disturbance but additionally offers better performance against multipath interference.
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 unrecoverable corruption of a reflected data stream or loud signals are discarded and tend to be retransmitted which slows the information rate and interrupts the information movement, the machine is less reliable for real time transmission. With advanced equalizer technologies, reflected or signals that are noisy not merely discarded or filtered down. Ahead mistake modification (FEC) algorithms usually takes corrupted signals and reconstruct them, notably reducing retransmits.
Data prices of over 20 Mbps will open up new applications for the industry to exploit. As might be expected, interest will almost certainly 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 are a way off nevertheless the WLAN is a market that is growing the statistics show. According to the latest figures from IDC WLAN that is worldwide equipment jumped 80% in 2000, breaking the $1 billion mark. IDC predicts that by the end of 2005 the market will be approaching $3.2 billion. Demand, especially in the US, has been particularly strong in vertical industries such as education, retail and health care. In the coming years, the market will see increased use of WLANs in the home and small- to medium-sized business (SMB) segments together with the growth of broadband. Despite the outlook that is optimistic the general market, especially in the united states, Western Europe and Japan, IDC thinks vendors will have to overcome a few obstacles, including resolving standardization problems, educating their partners, improving safety and reducing costs so that WLANs are affordable for mainstream portions.
The chipset market for 2.4 GHz WLAN products is placed to carry on to grow, 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 shall be driven by the development in traveling with a laptop and also by falling item expenses.
Bluetooth and WLANs could 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 associated with unknown. What exactly is known is the fact that 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. Nevertheless, what is as yet not known is the potential of this issue. The fact the devices run in an unlicensed band and projections of mushrooming market development for Bluetooth and 802.1lb is fueling concerns.
Even though degree of concern risk turning away to be unwarranted, it has at least grabbed the attention of wireless standards groups, regulatory figures and wireless industry participants. They are all well aware that if users do experience interference problems it will damage user confidence in the technology. With so investment that is much is a risk that manufacturers, in particular, cannot take. Global development that is technical is being completed and standards are now being addressed to restrict interference. 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, substantial research to monitor the end result that WiFi and Bluetooth products operating in identical vicinity have actually on one another is under way. Outcomes do vary and Figures 4 and 5 are examples of a study that is particular 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. Move the two antennas within a meter, however, and there may be significant interference.
Interference really becomes a issue that is serious both radios are integrated into the same device with the antennas close together. Examples of when the two devices are collocated (that is, separated by less than 10cm) are in a combination PC card and laptops or Internet appliances enabled with both technologies. Also, it is believed that collocated products will play an role that is important devices such as notebook PCs. A good example is a notebook that has a radio that is bluetooth for connection to a PDA or mobile phone and at the same time has a WiFi radio incorporated 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, together with industry partners, is a company taking care of developing an answer and has categorized these various technical approaches into 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 provides a single-card guide design only. The close proximity of the two radios with no coexistence procedure will likely create worst-case scenarios, and certainly will consequently cause significant degradation to both radios’ performance.
Dual-mode radio switching will not require changes to the silicon, and may be reasonably quick to market. It includes a coexistence device that needs that while one radio is functional, one other is totally 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 other nodes in its community. This will cause problems for the network and certainly will drop performance levels below that of simple ‘collocation without a coexistence procedure.’ The method that is second signal other network nodes that it is suspending one of its radios. Performance will still be 60 percent lower than that of unhindered radios because of its modal nature (one on/one off), but is much better than just shutting the radios down. Neither method supports switching while Bluetooth vocals (SCO) links are in operation.
Driver-level transmit switching generally describes an approach by which application transmit needs are mediated during the motorist level, thereby avoiding transmission that is simultaneous. Intuitively, this approach degrades throughput by some measure simply due to its modal transmit structure. More important, though, are its limitations while we are avoiding collisions with incoming packets. The ensuing transmission of 1 protocol during reception of this other notable 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 can be generally non-deterministic in its response time (non-real-time). Once more, this method will not switch quickly sufficient to support Bluetooth SCO links, and will also have problems mitigating the disturbance from Bluetooth piconet master/slave polling activities.
While Bluetooth adaptive hopping definitely improves simultaneous performance under limited penetration scenarios, its widespread adoption will likely require intervention from regulatory organizations and standards bodies. Even under a fast-track program, this can be a process that is time-consuming. This time-delay exacerbates the issue that the strategy’s effectiveness is compromised with higher 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, within the presence in excess of one Bluetooth piconet or WiFi network, adaptive hopping could be counter effective to coexistence.
MAC-level switching is the utmost 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 exchanging information between your two protocols at the MAC level and managing transmit/receive operations properly. Because MAC-level switching is conducted into the baseband, it is able to switch between protocols at a much faster rate than driver-level approaches. Consequently, it is able to mitigate many of the issues that driver-level switching cannot. MAC-level switching does not suffer from transmitting signals into incoming receptions, Bluetooth polling or operating system latency. Nonetheless, it is vunerable to interference that is adjacent-channel does suffer noticeable degradation. Also, because it is located in the baseband, it has a longer development cycle than driver-level approaches.
Simultaneous procedure offers the power to immediately identify all available wireless networks, 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 procedure associated with two protocols while eliminating disturbance and keeping reliability and performance. 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 operation that is smooth.
BLUETOOTH vs. WLAN APPLICATIONS
Bluetooth and WLAN can be competing into the same frequency band but are they competing for the same applications? Due to its simplicity in not having to be configured, low power, short range and low cost Bluetooth will be focused on small devices such as PDAs and cell phones. To provide access and synchronization of those personal devices there will also be the need for Bluetooth radios to be integrated in access points and notebooks.
Another possibility that Bluetooth affords is the deconstruction of products into specific components, allowing for new kind factors and device kinds. As an 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 public access. It’s all well to have synchronization between your notebook, PDA or cellular phone but, when in an airport or retail center, access to 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 ongoing company will not deploy Bluetooth enabled access points unless you will find significant variety of products available on the market to use them and vice versa. The same goes for the providers for the information that users will be seeking. Nevertheless, this is an certain 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 high data rate being comparable to the wired Ethernet makes them particularly suited to the enterprise sector for computer networking between PCs and to take advantage of the trend towards laptop computer mobility. Ease, low cost plus the facility for expansion also make WLAN suitable for small office home business office (SoHo) implementation and also the expansion of the property broadband access market, particularly in the united states, also starts up opportunities.
THE 5 GHZ FREQUENCY BAND
Whether or not simply a small fraction of these applications for Bluetooth and WLAN visited fruition, the narrow (80 GHz) 2.4 GHz musical organization will soon become congested. In anticipation of this, spectrum will play a crucial role in the deployment of next-generation, high speed WLANs and has prompted licensing authorities globally to allocate large blocks of license free spectrum in the 5 GHz band. A total of 455 MHz is available in the two blocks from 5.15 to 5.35 GHz and from 5.470 to 5.725 GHz as figure 7 shows, in Europe. Likewise, the US has allocated an overall total of 300 MHz in the two obstructs of range at 5.15 to 5.35 GHz and 5.725 to 5.825 GHz. In Japan, one 100 MHz block at 5.15 to 5.25 GHz has been considered.
Once again two different 5 GHz criteria are now being developed on either part for the Atlantic with both specifications providing information rates as high as 54 Mbps, and therefore well placed to deliver high speed communication 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 included in its Broadband Radio Access system (BRAN) effort. Under its remit is the growth of four criteria — HIPERLAN1, HIPERLAN2, HIPERLink (designed for interior radio backbones) and HIPERAccess (intended for fixed Outdoor used to provide use of a wired infrastructure).
The HIPERLAN1 standard, which can be on the basis of the well-established manner 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 levels of both 802.11a and HIPERLAN2 usage OFDM modulation to obtain high speed transmission rates. This multichannel spread spectrum modulation technique allows individual channels to maintain their distance (or orthogonality) to adjacent channels, enabling data symbols to be reliably extracted and multiple subchannels to overlap in the frequency domain for increased efficiency that is spectral. For instance, within the spectrum allocation for European countries, HIPERLAN2 stations 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 parallel data transfer, even though the staying four are employed as a reference to disregard frequency or period changes of this sign during transmission and supply synchronization. Synchronization enables coherent (in-phase) demodulation. The two standards may have this similarity but differ over the physical layer with 802.11a generally speaking seen as simpler and less complex, while HIPERLAN2 is mote sophisticated (or complicated according to your standpoint) with wider range.
For HIPERLAN2, mobile terminals such as for example a laptop 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 talk to one AP at each and every stage, 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 taking part in the handover ensure that established connections over the fresh air interface as well as security associations are transparently shifted from the old to the new. Security support includes both negotiation that is key authentication (conventions such as the netw ork access identifier (NAI) and X.509 may be used), in addition to encryption utilizing Diverses or 3-DES.
OFDM modulation can supply transmission prices of 54 Mbps but this is dynamically modified to a lower 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 support for quality of service (QoS), applied through time slots, straightforward. 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 specific length in transport stations. 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 fixed network; for instance, if it’s 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 networking that is common at layer 3 (internet protocol address and IPX, for example) will run over HIPERLAN2, allowing all common network-based applications to work, making the technology both community and application independent. Interoperation with Ethernet companies is supported right from the start, but extensions that are easy provide support for ATM, PPP, IP and UMTS. The standard has been specified with the objective that is clear of interoperability plus the industry consortium, HIPERLAN2 Global Forum (H2GF), aims to operate tests to confirm interoperability among products from user companies.
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 key application. 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 true and price-to-market is a problem. For instance, the higher price of silicon for OFDM procedure could stall fairly priced implementation. At present, expenses stay reasonably high for 5 GHz OFDM systems, due mainly to the linearity that is high that it places on the power amplifier in the transmitter and the low noise amplifier in the receiver. Consequently, HIPERLAN2 products will likely cost more than lower speed alternatives. Also, some view the fact that HIPERLAN2 is sophisticated and able to support a wide range of applications not necessarily as a selling point but as overkill that comes at a high price.
In the other hand, IEEE 802.lla, because of its simplicity and maturity, represents lower costs and a faster time-to-market. However, although 802.1la and HIPERLAN2 have a near identical physical layer, they vary within the MAC layer. Inadequacies include integrated quality of service, guaranteeing performance in work surroundings and when home video that is streaming. Therefore, efforts to close the MAC gap are a priority. Moreover, whereas the IEEE 802.lla and HIPERLAN2 both meet US spectrum that is regulatory, HIPERLAN2 is truly the only 5 GHz WLAN that meets European interference avoidance restrictions. Conversely, HIPERLAN2 must limit the regularity range and power for the US to adhere to FCC rules.
The danger is obvious because of the possibility that the US and European countries will embrace two different standards. The consequence that the corporates’ inability to use one standard and benefit from lower acquisition and support costs could delay deployment of 5GHz LANs that is wireless somewhat. It really is a serious issue for global development because they are two incompatible WLAN standards. Thus, if 802.lla and HIPERLAN2 wireless terminals were operating in the area that is same there is disturbance, no coexistence with no interworking. Also, no roaming is possible if different access points were deployed in different areas that are public. The end user shall have to make a standards option plus the 5 GHz WLAN market is in danger of being fragmented if different industry players adopt different standards.
In order to avoid this several industry partners have begun a 5 GHz industry advisory group. In the HIPERLAN2 ETSI BRAN group and 802.lla Forum there are sub groups specifically taking a look at what is required to arrive at one standard. At the moment, there was 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 update calendars, appointments and email whenever within range. Envisaged commercial applications range from the wireless monitoring of transported goods and chemical processes.
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 it should be, and to a great extent is, concentrating on steady development and addressing ways of ensuring interoperability, standardization and coexistence issues before it can run so. Bluetooth has its origins in European countries featuring its initial development focused in Scandinavia, and even though its truly 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 as well as perhaps a few 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 market growth that is significant. It is in a position to take advantage of the increase in the usage of laptop computers and development in house broadband access. Globally, 802.1lb systems are making inroads in ‘hot spot’ applications at airports, meeting facilities and accommodations, and WiFi items are hitting the market. Once more, issues of interoperability, coexistence and standardization are being addressed. However, although the establishment of a registered test house in Europe will assist acceptance, official certification has to become more extensive.
Utilizing the inevitability that the unlicensed 2.4 GHz band becomes congested, the development associated with the 5 GHz musical organization 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 real threat to international development and could wait implementation somewhat. A standards war will benefit nobody, perhaps undermining self-confidence and making manufacturers cautious about significant investment.
Going wireless has come with some strings connected but quick range wireless systems have 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, business 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, chairman HIPERLAN2 Global Forum and WLAN item supervisor at Ericsson, www.ericsson.com/wlan
* Peter Bates, VP company development, www.bluesocket.com
* Andy Craigen, senior manager, Wireless Terminals Applications, Agere Systems
* Bob Heile, chairman IEEE 802.15 Working Group
* The organizers and speakers at 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 club graph