The development of short range wireless systems, specially Bluetooth and wireless area that is local (WLAN) has captured the industry’s imagination, if not the market that was initially predicted. Bluetooth technology originated in Europe, with early research and development driven by European-based companies. In this special supplement Microwave Journal reviews current European activity, global expansion and globally competing technologies to find whether going wireless includes strings attached.
No wires — 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 mass that is tangled of presently required to connect a PC, not only to the network, but additionally to its peripherals such as for instance the keyboard, mouse and printer. Meanwhile, the mobility of mobile and technology that is cordless promoted ideas for a generic short range wireless access solution for different devices.
These are all desirable aims but the interest in and development of quick range wireless information networking hasn’t simply been prompted by the requirement to disentangle office chairs from trailing wires. The impetus that is real come from the desire and expectation of individuals and organizations to be able to access 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 so long as the technology is available to implement it.
With such a sizable 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 include how Bluetooth has generated 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 unique right.
BLUETOOTH: A SUMMARY
Since Ericsson initially devised the technology in 1994 Bluetooth has grabbed the imagination and most of the headlines. The business proceeded focusing on the project alone until February 1998, whenever it shared its research with Nokia, Intel, IBM and Toshiba to found the Bluetooth Special Interest Group (SIG). The main purpose of the SIG would be to protect the integrity associated with the technology and control its development. It is in charge of the certification process that all products must finish before they may be known as having a Bluetooth compliant product. Without official certification, a product cannot claim to be Bluetooth-enabled or use the Bluetooth trademark. The official certification procedure means that developers stick to the standard and ensure interoperability.
The commercial specification, Bluetooth 1.0, was issued in July 1999 and ratified in February of this year. The growth of activity in the technology is illustrated by the fact that there are currently some 2000 companies working on or developing products based on this specification. From its European origins — it’s named after a century that is 10th King — Bluetooth has inevitably become of international interest to both manufacturers and potential users.
The attraction is that Bluetooth can provide 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 high transmission rates. These features, along with help for real-time traffic of both vocals and data, ensure it is an attractive wireless technology that is networking personal digital assistants (PDA), mobile phones and laptops.
Licensed range is expensive, particularly in Europe ([greater than] $100 billion paid for 140 MHz). A major selling point of Bluetooth is it runs at the internationally available unlicensed industrial, scientific and medical (ISM) 2.4 GHz frequency musical organization, allowing 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 into 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 are set to keep in touch with a master radio in one single device. As Figure 3 illustrates, several of these piconets are established and linked together in advertisement hoc scatternets to permit 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 synchronous connection orientated (SCO) links for voice and asynchronous connectionless (AC) links for packet data. Both utilize time division duplex (TDD) as the access technique for full duplex transmission. Voice coding is accomplished using a continuously variable slope delta (CVSD) modulation strategy, under which voice packets will never be retransmitted. The master device controls the web link bandwidth and chooses how much bandwidth to give each servant and slaves should 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 products can help three voice stations running at 64 kbps, or one data channel, they could achieve information prices as high as 1Mbps. The Bluetooth 1.0 specification requires 1 mW transmitters with a antenna that is nominal of 0 dBm to operate as much as 10 m (type of sight). A higher energy transmitter of 100 mW (+20 dBm) contained in the specification increases the product range to 100 m, although this will require a separate PA antenna motorist. The compromise is increased costs and energy 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 whenever one device initiates a link and becomes the master of this piconet. An association is made by a full page message if the address is known, and if it is not then an inquiry message followed by a page message is sent. The devices synchronize and then connect. Each device assumes a media access control (MAC) address to distinguish them at the point of connection.
The Bluetooth technical specification may be clear, product roll-out less so. The marketing machines did their job in creating awareness but in the process raised expectations that have yet to be fulfilled. All too quickly allegations, particularly in the media, of over hype and over elaborate market forecasts were hitting the headlines. However, last year saw a significant number of product launches together with the initial shipments of products bearing the Bluetooth logo. There has been consolidation for the half that is first of year using the end of 2001 seeing significant predictions.
Frost & Sullivan forecasts worldwide deliveries of Bluetooth-enabled products to reach over 11 million units in 2001, equaling $2.5 billion in revenues, while Micrologic analysis is more conservative along with its estimation that the market shall reach five million devices in 2001 and 1.2 billion in 2005. Such variations in figures tend to muddy the waters and emphasize the unpredictability of the market, but in such an embryonic technology this is perhaps understandable.
This is certainly a point made by Michael Wall, research analyst at Frost & Sullivan, who has stated: “Although the delays in the development of Bluetooth are beginning to prompt a backlash from certain sections of the media, industry observers have to take the infancy of Bluetooth as an industry standard technology into consideration when assessing the status of this marketplace. Apart from Ericsson, the pioneers that are original even the most progressive designers were not drawn to the project until 1998. Other mobile communications technologies such as the GSM took longer to develop than is being allowed for Bluetooth.”
Semiconductor chipset development is a key aspect in the technology’s progress, with a variety of development designs appearing in the semiconductor industry that is bluetooth. Two manufacturing that is distinct are now being taken. There are either those offering complete integrated solutions through the silicon wafer level to the consumer item degree or those providing part of the amount of a chipset, that is, baseband, radio and computer software.
Debate continues over the most effective choice of silicon technology for Bluetooth. The diversity of silicon technologies and solutions architectures being used has emphasized the software protocol stack. It has become one of the most crucial elements of the solution, especially with regards to achieving interoperability and becomes increasingly crucial as semiconductor companies come closer to establishing their products onto the market.
A number of smaller design services companies have entered the Bluetooth software market offering complete or partial protocol stacks to semiconductor developers alongside some of the big names. In the same vein Bluetooth has offered a number of smaller, highly innovative fabless semiconductor developers, such as Cambridge Silicon Radio and Silicon Wave, an opportunity to build early market share with fast time-to-market solutions. Amongst the bigger built-in Bluetooth designers, Philips Semiconductors is the player that is main offer solutions in volume. It is expected that a number that is large of are going to be on offer by the conclusion of 2001.
Market success are dependant 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 future revenue streams for chipset suppliers. Despite such terms of care Frost & Sullivan forecasts that the total deliveries of Bluetooth chipsets will likely be over 956 million in 2006, plus 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 items, such as Computer cards and other add-on devices, together with access points (AP).
Additionally, in European countries, a number that is significant of mobile phones were launched at the CeBIT exhibition in Germany in March 2001 with many more expected over the summer. However, the market cocktail has become more intriguing because of 30 market developments. At a time when the cost that is huge of licenses is impacting on the telecoms currency markets as well as the equipment required to roll-out Universal Mobile Telecommunication System (UMTS) systems hasn’t yet visited fruition, most of the services planned for 3G mobile could possibly be delivered by currently available technologies which run in unlicensed (free) frequency bands.
Mobile operators who’ve 3G permit debts to service are under pressure to increase revenue of current information solutions, and prove that the marketplace has got the appetite for 2.5G and services that are 3G. Bluetooth mobile phones could be one solution by allowing users access to the Internet on their PDA using the phone as a gateway that is wireless. Ericsson, for example, is promoting the bluetooth information that is local (BLIP), which provides Bluetooth access to the Internet, within range of a BLIP access point. Such developments will continue to keep Bluetooth in the headlines and the eye that is public.
WLANs are 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 link that is wireless an access point and a wireless user interface card that is either part of the wireless device or attached to it. The technology is in no real way a newcomer, however. The IEEE 802.11 in fact, it was back in 1990 when, in the US Wireless Local Area Networks guidelines performing Group had been formed because of the task of developing a global standard for radio gear and companies operating within the 2.4GHz unlicensed frequency musical organization for data prices of just one and 2 Mbps.
Over 10 years ago what the first 802.11 standard did, to a qualification, was to greatly help unify a confused WLAN marketplace, that was crowded with proprietary solutions. Although the original specification supported three different transmission media — frequency hopping spread spectrum (FHSS), direct sequence spread spectrum (DSSS) and infrared (IR) — the major area of development has been for DSSS. DSSS spreads the signal over several frequencies, can switch channels to avoid interference and also makes the 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 binary phase shift keying (BPSK) where each symbol carries one bit and one million symbols per second (1 Msps) are transmitted. Thus, with each symbol storing one bit, the bit-rate achieved is 1 Mbps. Quadrature phase shift keying (QPSK) is the modulation scheme used to yield 2 Mbps. The system is able to transmit two channels simultaneously, and although the symbol rate is still 1 Msps with QPSK mapping two bits per symbol, the result yields 2 Mbps with this technique. However, these information prices of 1 Mbps and 2 Mbps are notably slow than the wired LAN equivalents. This aligned with questions over interperability and price, limited use up and acceptance of the standard as a viable option.
That all changed in September 1999 if the IEEE ratified a brand new rate that is high for WLANs – IEEE 802.11b, which also goes under the various guises of long range router (Wireless Fidelity) and high rate wireless Ethernet. It is significant because it offers a top-end data rate of 11 Mbps. Each access point can support lots of connections, although all of them must share 11 Mbps of ability. There might be three access points involved in the same area, and each typically has an indoor range of 90 m at 1 Mbps and 25 m at 11 Mbps. The IEEE 802.11 b specifies complementary code keying (CCK) as the modulation scheme to achieve this higher data rate. The technique maps four bits per sign to reach 8 Mbps, which allied to a heightened rate of 1.375 Msps yields a little rate of 11 Mbps. Therefore, while the number of symbols sent per second hardly varies from the symbol rate used for IEEE 802.11 LANs, more hits per second are sent. Also, as CCK is a DSSS technique, 802.11 b is backward-compatible with products that meet the origin al 802.11 specification, enabling 802.11b products that are standard interoperate with 802.11 compliant DSSS items by falling back once again to 1 Mbps or 2 Mbps procedure.
With a business human body to verify interoperability as well as the interoperability of 802.11b cards being guaranteed, due to there being simply two silicon manufacturers worldwide making use of a MAC that is similar layer, that deficiency in the WLAN offering has been addressed. The increased bit rate of 11 Mbps has also dealt with the performance issue with 802.11b being able to match standard Ethernet for speed. It has led to a renewed fascination with, and maybe more to the point, investment within the development of 802.11b products by large players whom did not see any participation in 1 or 2 Mbps items as a option that is viable.
Now, the benefits that WLANs offer when it comes to mobility and flexibility, allied to increased speed therefore the falling costs of PC cards, has made it 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 communicate with fixed Ethernet topologies via an Ethernet hub or switch port. Although WLAN cards are still much 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 towards the progress of WiFi is its wide and global deployment, and without any hype it has begun. Airports as far afield as Europe, Japan, Hong Kong and the US have installed 802.llb networks, with accommodations and seminar centers additionally being prime aspects of development. Furthermore, because of the increased use of laptops, the natural synergy between their mobility and the mobility offered by WLANs is propelling the growth of 802.llb. Offering mobility is going to be the key to success of WiFi. For instance, when users have a notebook, they want to be able to use it in the workplace, at home and on their travels and never having to swap cards. Only a deployment that is wide of will facilitate that.
Mobile operators additionally see WLANs as an inexpensive 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. Again, at CeBit there were many equipment companies showing WiFi components by means of Computer cards, universal bus that is serialUSB) devices, access points and home gateways. However, at present the Wireless Ethernet Compatibility Alliance (WECA) only recognizes one test house in the US for certification of WiFi products with plans for a test that is european to be recognized soon. Such expansion is a must for the technology to be viewed as truly worldwide with regards to development.
The important thing element in the development and development associated with WLAN market was the increased information 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 info rates will likely be risen to more than 20 Mbps plus the mission of this task group would be to review proposals. Regions of development currently being undertaken which could afford this ‘doubled’ information rate include a modulation that is new that improves the robustness of RF information transmissions. It not only overcomes a lot of the backdrop RF noise and other sources of interference but in addition offers better performance against multipath interference.
On the receiver side, advanced technology that is equalizer in concert with these new modulation algorithms will act to reduce the need to retransmit data packets. This is important because when interference in WLANs causes unrecoverable corruption of a reflected data stream or loud signals are discarded and they are retransmitted which slows the information rate and interrupts the info flow, the machine is less reliable for real-time transmission. With advanced equalizer technologies, reflected or signals that are noisy not only discarded or filtered out. Forward error modification (FEC) algorithms may take corrupted signals and reconstruct them, dramatically reducing retransmits.
Data prices of over 20 Mbps will open applications that are new the industry to exploit. As might be expected, interest shall likely be led by leisure applications. Faster transmission speeds will enable streaming video for high definition television and graphics for interactive gaming while also providing the headroom to accommodate new applications when they come on stream. Businesses and enterprises are always screaming out for the means to transmit large amounts of data quickly. Home automation will be another avenue by facilitating the interaction of heating, lighting, air conditioning and security systems.
THE WLAN MARKET
Such applications are some way off nevertheless the WLAN is a growing market as 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. The market will see increased use of WLANs in the home and small- to medium-sized business (SMB) segments together with the growth of broadband in the coming years. Regardless of the optimistic outlook for the overall market, especially in the united states, Western Europe and Japan, IDC believes vendors will need to over come a few obstacles, including resolving standardization dilemmas, educating their partners, improving safety and reducing costs making sure that WLANs are affordable for mainstream sections.
The chipset market for 2.4 GHz WLAN products is set to keep to expand, although growth shall not be as high as for Bluetooth chipsets. Frost & Sullivan anticipates sequence 802.11b that is direct chipsets to be in great demand, predicting that the market for them will be worth over $1.3 billion in 2006. This demand will be driven by the development in traveling with a laptop and also by falling item costs.
Bluetooth and WLANs might 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 is becoming a fear of the 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. Nonetheless, what exactly is as yet not known is the potential of the issue. The truth that the products run in an unlicensed band and projections of mushrooming market development for Bluetooth and 802.1lb is fueling concerns.
Although the level of concern risk turning down to be unwarranted, it offers at the least grabbed the eye of wireless criteria groups, regulatory systems and wireless industry participants. They are all well aware that if users do experience interference problems it will harm user confidence within the technology. With so investment that is much is a risk that manufacturers, in particular, cannot take. Global development that is technical is being performed and standards are now being addressed to limit 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 end result that WiFi and Bluetooth products operating in identical vicinity have on one another is under way. Outcomes do vary and Figures 4 and 5 are samples of a particular study to illustrate the effect. However, what is generally accepted is that if the antennas of the Bluetooth and WiFi devices are kept over 2m apart, then there will be graceful degradation of the two protocols, which will only be noticed by very sensitive users. Move the two antennas within a meter, but, and there may 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 instance notebook PCs. An example is a notebook which has a radio that is bluetooth for connection to a PDA or cellular phone and as well has a WiFi radio incorporated for LAN access.
Coexistence is a major issue for such applications and one which the industry is striving to address with standards bodies and wireless companies starting to develop and lobby for a variety of coexistence approaches. These vary from regulatory intervention and special standards task forces such as IEEE 802.15.2 to various technical approaches ranging from simple device ‘collocation without any coexistence mechanisms’ to integrated silicon solutions covering the entire sub-system that is wireless.
Mobilian Corporation, together with industry partners, is a company focusing on developing a solution and contains categorized these various approaches that are technical a performance and user experience hierarchy, as shown in Figure 6, with each having their strengths and limitations. ‘Collocation without a coexistence mechanism ‘is relatively controversial. It does have the advantage of being a rapid time-to-market approach which supplies a single-card reference design just. The close proximity of the two radios without any coexistence procedure will probably produce worst-case situations, and certainly will consequently lead to significant degradation to both radios’ performance.
Dual-mode radio switching will not need modifications towards the silicon, and might be reasonably quick to advertise. It includes a coexistence procedure that needs that while one radio is functional, the other is wholly suspended. The operation can be implemented primarily in two ways. In the first, the system simply shuts the non-operating radio off with no signaling to many other nodes in its network. This could cause difficulties for the system and will drop performance levels below that of easy ‘collocation without a coexistence mechanism.’ The second method does signal other network nodes that it is suspending one of its radios. Performance will still be 60 percent lower than that of unhindered radios because of its modal nature (one on/one off), but is much better than merely shutting the radios off. Neither method supports switching while Bluetooth vocals (SCO) links are in operation.
Driver-level transmit switching generally describes a strategy by which application transmit demands are mediated during the driver level, thereby avoiding transmission that is simultaneous. Intuitively, this approach degrades throughput by some measure simply due to its transmit that is modal structure. More important, though, are its limitations in avoiding collisions with incoming packets. The resulting transmission of 1 protocol during reception of this other notable causes loss in gotten packets, disturbance and potential user difficulties. This is caused by the technique’s dependence on the host operating system, that will be generally non-deterministic in its reaction time (non-real-time). Once more, this process does not switch quickly enough to guide Bluetooth SCO links, and will also have problems mitigating the interference from Bluetooth piconet master/slave polling activities.
While Bluetooth adaptive hopping truly improves performance that is simultaneous limited penetration scenarios, its widespread adoption will likely require intervention from regulatory organizations and standards bodies. Even under a fast-track program, this can be a process that is time-consuming. This time-delay exacerbates the issue that the strategy’s effectiveness is compromised with higher penetrations of WiFi systems and unmodified Bluetooth devices. Adaptive hopping will likely be initiated as an Bluetooth that is optional profile indicating that modified products will not use the functionality in piconets with unmodified products. Further, into the existence in excess of one piconet that is bluetooth WiFi system, adaptive hopping may be counter productive to coexistence.
MAC-level switching is the utmost effective associated with the style that is modal/switching, and provides performance levels approaching those in no-interference scenarios. It is a collaborative technique accomplished by trading information involving the two protocols during the MAC level and managing transmit/receive operations appropriately. Because MAC-level switching is carried out into the baseband, it is able to switch between protocols at a much quicker rate than driver-level approaches. Consequently, with the ability to mitigate many of the conditions 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. Nonetheless, its vunerable to adjacent-channel interference and does suffer noticeable degradation. Also, it has a longer development cycle than driver-level approaches because it is located in the baseband.
Simultaneous procedure supplies the ability 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 digital baseband chip – it allows simultaneous operation associated with the 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 smooth operation.
BLUETOOTH vs. WLAN APPLICATIONS
Bluetooth and WLAN are competing into 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 devices that are personal will also be the need for Bluetooth radios to be included in access points and notebooks.
Another possibility that Bluetooth affords is the deconstruction of devices into individual elements, permitting brand new kind factors and device types. As an example, by having a headset that is separate 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 very well to own synchronization involving the notebook, PDA or cellular phone but, when in an airport or plaza, usage 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 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. Similar goes for the providers for the information that users will be seeking. Nevertheless, this is an area earnestly being develop ed.
Public access is a application that is definite WLAN and, as has been mentioned, systems are already being globally deployed in airports. Their high data rate being comparable to the wired Ethernet makes them especially ideal for the enterprise sector for computer networking between PCs also to use the trend towards laptop computer flexibility. Convenience, inexpensive plus the center for expansion additionally make WLAN suitable for tiny workplace office at home (SoHo) implementation and the expansion of the property broadband access market, especially in the united states, also starts up opportunities.
THE 5 GHZ FREQUENCY BAND
Whether or not simply a fraction of those applications for Bluetooth and WLAN arrive at fruition, the slim (80 GHz) 2.4 GHz musical organization will soon become congested. In anticipation of the, 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. 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. Similarly, the united states has allocated a complete of 300 MHz into the two blocks 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 is being considered.
Once again two different 5 GHz criteria are being developed on either part associated with the Atlantic with both specifications offering data prices as high as 54 Mbps, and therefore well placed to provide speed that is high services. Originating in the US the IEEE 802.11a standard was ratified in 1999. The physical layer (PHY) is based on orthogonal frequency division multiplexing (OFDM) and shares a common MAC layer with all IEEE 802.11 standards including 802.11b.
Instead the European Telecommunications 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 growth of four standards — HIPERLAN1, HIPERLAN2, HIPERLink (made for interior radio backbones) and HIPERAccess (designed for fixed exterior use to provide usage of a wired infrastructure).
The HIPERLAN1 standard, which can be in line with the well-established means of Gaussian shift that is minimum (GMSK) modulation, is complete and was ratified in 1997. HIPERLink and HIPERAccess, on the other hand, are at the early stages of development. It is HIPERLAN2 where activity that is current focused.
The physical layers of both 802.11a and HIPERLAN2 usage OFDM modulation to attain speed that is high rates. This multichannel spread spectrum modulation technique allows individual channels to maintain their distance (or orthogonality) to adjacent channels, enabling data symbols to be reliably extracted and multiple subchannels to overlap in the frequency domain for increased efficiency that is spectral. For instance, within the range allocation for European countries, HIPERLAN2 stations is going to be spaced 20 MHz apart for a complete 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, whilst the staying four are employed as a reference to disregard frequency or phase shifts for the signal during transmission and provide synchronization. Synchronization enables coherent (in-phase) demodulation. The 2 criteria may have this similarity but vary above the layer that is physical 802.11a generally seen as easier and less complex, while HIPERLAN2 is mote sophisticated (or complicated depending on your standpoint) with wider scope.
For HIPERLAN2, mobile terminals such as a laptop or handheld devices talk to access points. These access points must have overlapping coverage areas to provide continuous coverage. Coverage typically extends 30 m indoors and 150 m in unobstructed environments. By utilizing automatic frequency allocation (AFA) access points monitor the HIPERLAN radio channels around them and automatically select an unused channel. A mobile terminal, after association, will only communicate with one AP at each and every point in time, but if it receives a better signal strength it can request to be connected to another. When a mobile terminal roams from the coverage area of one access point to another, it automatically initiates a handoff to the new access point. The APs involved with 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 key negotiation, authentication (conventions such as for example the netw ork access identifier (NAI) and X.509 can be utilized), in addition to encryption utilizing Diverses or 3-DES.
OFDM modulation can provide transmission prices of 54 Mbps but this can be dynamically modified to less rate by making use of 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 broadcast and multicast traffic. This approach 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 time that is specific for a certain period in transportation channels. The terminal that is mobile sends data without interruption from other mobile terminals operating on that frequency. A control channel provides feedback to the sender, indicating whether data was received in error and whether it must be retransmitted. The QoS de livered depends on how the HIPERLAN2 network interoperates with the network that is fixed for instance, in case it is via packet-based Ethernet, cell-based ATM or IP.
HIPERLAN2 functions as a extension that is seamless of networks, so wired network nodes see HIPERLAN2 nodes as other network nodes. All networking that is common at layer 3 (IP and IPX, as an example) will run over HIPERLAN2, allowing all common network-based applications to use, making the technology both community and application independent. Interoperation with Ethernet companies is supported right from the start, but easy extensions also provide support for ATM, PPP, IP and UMTS. The standard has been specified with the clear objective of achieving interoperability plus the industry consortium, HIPERLAN2 Global Forum (H2GF), aims to operate tests to verify interoperability among items from member companies.
The absolute most obvious application for HIPERLAN2 will be in the enterprise LAN environment but networks can also be deployed at ‘hot spot’ areas such as airports and hotels, supplying remote access and Internet services to business people. Its ability to act as an alternative access technology to 3G cellular networks is also a application that is key. 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 an issue. For example, the bigger price of silicon for OFDM operation could stall reasonably priced execution. At the moment, costs stay fairly high for 5 GHz OFDM systems, due primarily to the high linearity demands that it places on the power amplifier in the transmitter and the low noise amplifier in the receiver. Consequently, HIPERLAN2 products will likely cost more than lower speed alternatives. Also, some view the fact that HIPERLAN2 is sophisticated and able to support a wide range of applications definitely not as a selling point but as overkill that comes at a cost.
In the other hand, IEEE 802.lla, due to its simplicity and maturity, represents lower costs and a faster time-to-market. However, although 802.1la and HIPERLAN2 have a near identical physical layer, they differ within the MAC layer. Inadequacies include built-in quality of service, guaranteeing performance in work surroundings when streaming home video. Therefore, efforts to close the MAC gap are a priority. Moreover, whereas the IEEE 802.lla and HIPERLAN2 both meet US regulatory spectrum requirements, HIPERLAN2 is the only real 5 GHz WLAN that satisfies European disturbance avoidance restrictions. Conversely, HIPERLAN2 must limit the frequency power and range for the US to comply with FCC rules.
The danger is apparent using the possibility that the US and Europe will embrace two standards that are different. The consequence that the corporates’ inability to use one standard and benefit from lower acquisition and support costs could delay deployment of 5GHz wireless LANs considerably. It’s 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 with no interworking. Also, no roaming will be feasible if different access points had been implemented in different areas that are public. The end user will be required to make a standards option therefore the 5 GHz WLAN market is in danger of being fragmented if different industry players follow different standards.
In order to avoid this a few 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 evaluating what is necessary to reach one standard. At the moment, there was work that is much be done.
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 immediately upgrade calendars, appointments and email when within range. Envisaged commercial applications include the wireless monitoring of transported goods and chemical processes.
But, all of the early applications are 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 with its initial development focused in Scandinavia, and though its really a technology that is global that is where its early deployment will be greatest. Bluetooth has attracted all the players that are key investment is considerable and maybe some of the hype is justified.
The IEEE 802.llb (WiFi) WLAN standard has been developed steadily without any razzmatazz on the other side of the coin and the Atlantic, but in the same 2.4 GHz unlicensed frequency band. Its high data rate, together with the falling costs of PC cards, allied to the mobility and flexibility it offers has seen significant market growth. It really is in a position to enjoy the rise within the usage of laptops and development in house broadband access. Globally, 802.1lb companies are making inroads in ‘hot spot’ applications at airports, conference centers and resort hotels, and WiFi products are striking the market. Once more, issues of interoperability, standardization and coexistence are being addressed. However, although the establishment of a test that is registered in Europe will assist acceptance, certification needs to become more extensive.
Aided by the inevitability that the unlicensed 2.4 GHz musical organization will end up congested, the development associated with the 5 GHz band for next generation high speed WLANs is vital. However, the possibility of fragmentation, with separate standards being adopted in the US and Europe is a threat that is real global development and could wait implementation dramatically. A standards war will benefit no body, possibly undermining self-confidence and making manufacturers wary of significant investment.
Going wireless has include some strings connected but short range wireless systems have actually a long term future. Its ability to satisfy the industry’s desire for seamless connectivity will ensure continued market growth and development.
Mcdougal would like to thank the following individuals and organizations for their aid in compiling this supplement:
* Mobilian Corporation, www.mobilian.com
* Vincent Vermeer, business development supervisor — 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, chairman HIPERLAN2 Global Forum and WLAN item manager at Ericsson, www.ericsson.com/wlan
* Peter Bates, VP company development, www.bluesocket.com
* Andy Craigen, senior manager, Wireless Terminals Applications, Agere techniques
* Bob Heile, chairman IEEE 802.15 Working Group
* The organizers and speakers during the LAN that is wireless conference London in April 2001. Arranged by EF-Telecoms, www.ef-international.co.uk
* Frost & Sullivan, www.frost.com
* Figure 2 and Figure 3 are taken with authorization from presentations available on www.ieee802.org/15/ EUROPEAN 3G SPECTRUM AT [greater than]$700 M PER MHz PRICE $B GERMANY 47.5 UK 32.9 ITALY 11.4 FRANCE 9.3 Note: Table made from club graph
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