Ultra Wide Band

UWB is a wireless technology that transmits binary data—the 0s and 1s that are the digital building blocks of modern information systems. It uses low-energy and extremely short duration (in the order of pico seconds) impulses or bursts of RF (radio frequency) energy over a wide spectrum of frequencies, to transmit data over short to medium distances, say about 15—100 m. It doesn’t use carrier wave to transmit data.

UWB is fundamentally different from existing radio frequency technology. For radios today, picture a guy watering his lawn with a garden hose and moving the hose up and down in a smooth vertical motion. You can see a continuous stream of water in an undulating wave. Nearly all radios, cell phones, wireless LANs and so on are like that: a continuous signal that's overlaid with information by using one of several modulation techniques.

Now picture the same guy watering his lawn with a swiveling sprinkler that shoots many, fast, short pulses of water. That's typically what UWB is like: millions of very short, very fast, precisely timed bursts or pulses of energy, measured in nanoseconds and covering a very wide area. By varying the pulse timing according to a complex code, a pulse can represent either a zero or a one: the basis of digital communications.

Wireless technologies such as 802.11b and short-range Bluetooth radios eventually could be replaced by UWB products that would have a throughput capacity 1,000 times greater than 802.11b (11M bit/sec). Those numbers mean UWB systems have the potential to support many more users, at much higher speeds and lower costs, than current wireless LAN systems. Current UWB devices can transmit data up to 100 Mbps, compared to the 1 Mbps of Bluetooth and the 11 Mbps of 802.11b. Best of all, it costs a fraction of current technologies like Blue-tooth, WLANs and Wi-Fi.

 

ULTRA-WIDEBAND OPERATION

This part sets out the regulations for unlicensed ultra-wideband transmission systems.

Definitions.

(a)  UWB Bandwidth.  For the purpose of this subpart, the UWB bandwidth is the frequency band bounded by the points that are 10 dB below the highest radiated emission, as based on the complete transmission system including the antenna. The upper boundary is designated f_H and the lower boundary is designated f_L.  The frequency at which the highest radiated emission occurs is designated f_M.

(b)  Center frequency.  The center frequency, f_C, equals (f_H + f_L)/2.

(c)  Fractional bandwidth.  The fractional bandwidth equals 2(f_H - f_L)/ (f_H + f_L).

(d)  Ultra-wideband (UWB) transmitter.  An intentional radiator that, at any point in time, has a fractional bandwidth equal to or greater than 0.20 or has a UWB bandwidth equal to or greater than 500 MHz, regardless of the fractional bandwidth.

(e)  Imaging system.  A general category consisting of ground penetrating radar systems, medical imaging systems, wall imaging systems through-wall imaging systems and surveillance systems.  As used in this subpart, imaging systems do not include systems designed to detect the location of tags or systems used to transfer voice or data information.

(f)  Ground penetrating radar (GPR) system.  A field disturbance sensor that is designed to operate only when in contact with, or within one meter of, the ground for the purpose of detecting or obtaining the images of buried objects or determining the physical properties within the ground.  The energy from the GPR is intentionally directed down into the ground for this purpose.

(g)  Medical imaging system.  A field disturbance sensor that is designed to detect the location or movement of objects within the body of a person or animal.

(h)  Wall imaging system.  A field disturbance sensor that is designed to detect the location of objects contained within a “wall” or to determine the physical properties within the “wall.”  The “wall” is a concrete structure, the side of a bridge, the wall of a mine or another physical structure that is dense enough and thick enough to absorb the majority of the signal transmitted by the imaging system.  This category of equipment does not include products such as “stud locators” that are designed to locate objects behind gypsum, plaster or similar walls that are not capable of absorbing the transmitted signal.

(i)  Through-wall imaging system.  A field disturbance sensor that is designed to detect the location or movement of persons or objects that are located on the other side of an opaque structure such as a wall or a ceiling. This category of equipment may include products such as “stud locators” that are designed to locate objects behind gypsum, plaster or similar walls that are not thick enough or dense enough to absorb the transmitted signal.

(j)  Surveillance system.  A field disturbance sensor used to establish a stationary RF perimeter field that is used for security purposes to detect the intrusion of persons or objects.

(k)  EIRP.  Equivalent isotropically radiated power, i.e., the product of the power supplied to the antenna and the antenna gain in a given direction relative to an isotropic antenna.  The EIRP, in terms of dBm, can be converted to a field strength, in dBuV/m at 3 meters, by adding 95.2. As used in this subpart, EIRP refers to the highest signal strength measured in any direction and at any frequency from the UWB device.

(l)  Law enforcement, fire and emergency rescue organizations.  As used in this subpart, this refers to those parties eligible to obtain a license from the FCC under the eligibility requirements specified.

(m)  Hand held.  As used in this subpart, a hand held device is a portable device, such as a lap top computer or a PDA, that is primarily hand held while being operated and that does not employ a fixed infrastructure.

ULTRA WIDE BAND- A WIRELESS DATA TRANSFER TECHNOLOGY

The concepts of communication and computation are so close that their tight connection is obvious even for PR departments of major IT companies. Quite often it makes no sense to separate these concepts. Today, speaking about growing power of computing devices we imply both growing performance of their processors and growing throughput of their communication channels. The communication channels include internal: 

• caches
• system buses
• memory interfaces
• interfaces of storage devices

...and external: 

• interfaces of peripherals
• wireless network channels
• wired network channels

structures of data transfer. 

External wired communication channels are developing mainly in two directions - cost reduction and increase of availability of optical channels (top-down) and growth of throughput (bottum-up). However, the two physical carriers are not so close yet (first of all, in prices) to be involved in direct competition - in 90% of cases a character of a problem to be solved determines the technology to be preferred. 

Internal wired channels are switching over from specialized parallel interfaces to high-level serial packet interface (Serial ATA, 3GIO/PCI Express, Hyper Transport). It fosters a convergence of external and internal communication technologies: in future separate components of a computer case will be combined into a normal network. It's quite a logical solution - a modern chipset, thus, works as a network switch equipped with multiple interfaces such as a DDR memory bus or a processor bus and AGP/PCI. 

Wireless channels are just at the formation stage now in terms of the range of applications. Today they can be used effectively only for a small part of communication tasks, including the most important problem of developing a global network infrastructure. Wireless technologies are only partially suitable for local communications, first of all, because of a low throughput. At present, there are two prevailing wireless standards: 

• BlueTooth - a wireless interface of a low throughtput for peripherals and communication between objects located not very far from each other. 
• 802.11a / 802.11b - a standard Ethernet network with a common medium for developing a general-purpose network infrastructure. 

The BlueTooth and its followers will free your workplace from cables replacing them with multiple low-speed peripheral interfaces (keyboard, mouse, undemanding scanner or printer, IrDA). The 802 standard will play a role of the "last network interface" connecting the infrastructure and end access points. The first type of the 802 standard has a high throughput, over 50 Mbit, and is primarily meant for saturated and compact networks of enterprises and offices. The base frequency (5 GHz) penetrates much worse into neighboring rooms than 2.4 GHz of the 11Mbit standard. The 802.11b standard is a match for home and various residential and public structures such as airports, cafes, cinemas, trade houses. 

Cellular communication standards, including the struggling 3G, are the candidates for a wide territorial data transfer standard. But the widespreading 802.11 can make problems for the third generation of cellular networks as their niches overlap a lot. 

Now turning to the peripherals and internal communications , having a too narrow bandwidth for printing, scanning and data exchange with wireless terminals, the BlueTooth is not a good choice as an internal wireless interface either. Pop into the computer case, there are still a lot of cables in there... 

What should we have ideally: 

• A bandwidth must satisfy the needs of drives, i.e. it must be 10-100 times wider than that for the infrastructure. 
• Operation both at short and mid-range distances to cover not only intrasystem communications but also the infrastructure niche of the 802 standard and the niche of external peripherals. 
• Much lower cost of implementation - lower than for the 802 and BlueTooth. 
• Simplicity of realization - possibility to develop single-chip solutions that do not need any additional discrete and analog parts or even integration of such solutions into highly integrated general-purpose chips. 

At first glance, it's impossible to combine these requirements in the near future. However: 

Ultra Wide Band

 

This concept doesn't stand for a definite standard of wireless communication.This is a method of modulation and data transmission which can entirely change the wireless picture in the near future. The diagram given below demonstrates the basic principle of the UWB: 

The UWB is above and the traditional modulation is below which is called here Narrow Band (NB), as opposed to the Ultra Wideband. On the left we can see a signal on the time axis and on the right there is its frequency spectrum, i.e. energy distribution in the frequency band. The most modern standards of data transmission are NB standards - all of them work within a quite narrow frequency band allowing for just small deviations from the base (or carrier) frequency. Below on the right you can see a spectral energy distribution of a typical 802.11b transmitter. It has a very narrow (80 MHz for one channel) dedicated spectral band with the reference frequency of 2.4 GHz. Within this narrow band the transmitter emits a considerable amount of energy necessary for the following reliable reception within the designed range of distance (100 m for the 802.11b). The range is strictly defined by FCC and other regulatory bodies and requires licensing. Data are encoded and transferred using the method of frequency modulation (control of deviation from the base frequency) within the described channel. 

Now take a look at the UWB - here the traditional approach is turned upside down. In the time space the transmitter emits short pulses of a special form which distributes all the energy of the pulse within the given, quite wide, spectral range (approximately from 3 GHz to 10 GHz). Data, in their turn, are encoded with polarity and mutual positions of pulses. With much total power delivered into the air and, therefore, a long distance of the reliable reception, the UWB signal doesn't exceed an extremely low value (much lower than that of the NB signals) in each given spectrum point (i.e. in each definite licensed frequency band). As a result, according to the respective FCC regulation, such signal becomes allowable although it also takes spectral parts used for other purposes: 

So, the most part of energy of the UWB signal falls into the frequency range from 3.1 to 10.6 GHz. Below 3.1 GHz the signal almost disappears. The more ideal the form of a pulse formed with the transmitter, the less the energy goes out of the main range. The spectral range lower than 3.1 GHz is avoided not to create problems for GPS systems.  However, UWB is accurate to within 10 centimeters -- much better than the Global Positioning System satellites and because it spans the entire frequency spectrum (licensed and unlicensed), it can be used indoors and underground, unlike GPS. UWB could replace communications of all types, ending forever our dependence on wires and making worthless the ownership of radio frequencies.

The total energy of the transmitter which can fit into this band is defined by the area of the spectral characteristic (see filled zones on the previous picture). In case of the UWB it's much greater compared to the traditional NB signals such as 802.11b or 802.11a. So, with the UWB we can send data for longer distances, or send more data, especially if there are a lot of simultaneously working devices located close to each other. Here is a diagram with the designed maximum density of data transferred per square meter:

Density of transferred data able to coexist on the same square meter is much higher for the UWB compared to the popular NB standards. That is, it will be possible to use the UWB for the intrasystem communication or even for an interchip communication within one device! 

The UWB actually tries to solve the problem of inefficient spectrum utilization, like the Hyper Threading solves the problem of idle time of functional processor units. Frequency bands dedicated for different services remain unused for the most part of time - even in a very dense city environment - at each given point of time the most part of the spectrum is not used, that is why the radio spectrum is used irrationally: 

1. Most frequencies are not used all the time. That is a low frequency effectiveness of the spectrum utilization.  
2. Guard channels necessary for NB modulations (gaps between channels to eliminate pickups). That is a low frequency effectiveness of the spectrum utilization. 
3. Excessive and, as a rule, uncontrolled power of transmission (and, therefore, transmission range) of signals even if a distance is quite short. That is a low spatial effectiveness of the spectrum utilization. 

In case of the NB a frequency and width of the dedicated spectral range for the most part (though the real situation is much more complicated) defines a bandwidth of the channel, and the transmitter's power defines a distance range. But in the UWB these two concepts interwine and we can distribute our capabilities between the distance range and bandwidth. Thus, at small distances, for example, in case of an interchip communication, we can get huge throughput levels without increasing the total transferred power and without cluttering up the air, i.e. other devices are not impeded. Look at how the throughput of data transferred in the UWB modulation depends on distance: 

While the traditional NB standard 802.11a uses an artificially created dependence of throughput on distance (a fixed set of bandwidths discretely switched over as the distance increases), the UWB realizes this dependence in a much more natural way. At short distances its throughput is so great that it makes our dreams on the interchip communication real, but at the longer distances the UWB loses to the NB standard. On the one hand, a theoretical volume of the energy transferred, and therefore, the maximum amount of data, is higher. On the other hand, we must remember that in a real life information is always transferred in large excess. Beside the amount of energy, there is the design philosophy which also has an effect. For example, a character of modulation, i.e. how stably and losslessly it is received and detected by the receiver. Let's compare the classical: 

The classical transceiver contains a reference oscillator (synth) which, as a rule, is stabilized with some reference crystal element (Ref Osc). Further, in case of reception this frequency is subtracted from the received signal, and in case of transmission it is added to the data transferred. For the UWB the transmitter looks very unsophisticated - we just form a pulse of a required shape and send it to the antenna. In case of reception we amplify the signal, pump it through the band filter which selects our working spectrum range and... that's all - here is our ready pulse. The only problem is how to detect it! Here is the key how to increase the effective distance for the UWB. Of course, it's much more difficult to detect a single pulse than a series of oscillations of the carrier frequency. So, for the UWB to succeed we must create not only keys (pulse oscillators) of a strictly defined form and a switch time of around 3 GHz, but also develop high-quality detectors of such pulses which is a loads more complicated problem. However that may be but the UWB is much simpler than NB transceivers and can be entirely assembled on a chip. The most important advantage is that a UWB transmitter needs no its analog part - a signal can be sent to the air right from the chip, and in case of reception this analog part is much simpler and can be realized within the frames of not only hybrid technologies but also base ones, i.e. CMOS and the like. 

One more interesting aspect of the UWB comes from radio location (where wideband technologies were most often used before): a potential possibility to create networks able to define geometrical positions of objects. It requires sets (grids) of antennae which are very easy to make for the UWB. It can be very useful for addressing objects - just imagine a universal control radio console which knows which device it is aimed at  the given moment. One more application is creation of a dynamic antenna directivity diagram to improve reception of signals from a definite device, ignoring signals from others. This approach is going to improve even more the spatial effectiveness of the air utilization. 

The first standards and products based on the UWB will be available in 2005. 

And finally, here is a comparison table of the characteristics:   

	Distance range, m	Frequency	Channel width	Throughput
UWB	Up to 50 (at present)	3.1 to 10.6 GHz	The same	Hundreds of Mbit
802.11b	100	2.4 GHz	80 MHz	Up to 11 Mbit
802.11a	50	5 GHz	200 MHz	Up to 54 Mbit
BlueTooth	10	2.4 GHz		Up to 1 Mbit

Why is UWB so Effective?

The Hartley-Shannon Law –

C =B (log (1+S/N))/log2

Where:

C = Max Channel Capacity

(bits/sec)

B = Channel Bandwidth (Hz)

S = Signal Power (watts)

N = Noise Power (watts)

C grows linearly with B,

but only logarithmically

with S/N. Since B is very high C also become very high.

ULTRA WIDE BAND IS ULTRA FAST

In amplitude modulation, the sine wave of the data is combined with the sine wave of the transmitter before transmission. Here the peak-to peak-voltage of the transmitted wave will change according to the data

Its significance lies in the fact that it transmits several times the data possible over current wireless technologies, using very low levels of power (in the order of a few milliwatts). Current UWB devices can transmit data up to 100 Mbps, compared to the 1 Mbps of Bluetooth and the 11 Mbps of 802.11b. It’s expected to reach around 500 Mbps by 2004. Also, this low power pulse can penetrate obstacles like doors, walls, metal etc, and suffers little or no interference from other narrow band frequencies. Hence, it is useful in densely built-up areas. It doesn’t require allocation of ‘precious’ or ‘paid for’ narrow-band spectrum, in use now. Supporters of UWB say that its electro-magnetic noise is only as much as that of a hair dryer or electric fan, and it doesn’t interfere with or hamper other RFs. Best of all, it costs a fraction of current technologies like Blue-tooth, WLANs and Wi-Fi.

Back to basics

To understand UWB, we’ll first look at radio communication and how data is transmitted traditionally. All of us have dropped pebbles in a water pool at some point in our lives. Remember the ripples traveling outwards from the point where the pebble enters the water up to the boundary? 

Normal radio waves are sine waves or smoothly fluctuating waves like these ripples. Traditionally, radio communications stay within the allocated frequency band. We normally use a carrier wave to transmit data. The carrier wave is imprinted with data by modulating any of the following— amplitude, frequency or phase of the carrier wave. Three common ways of modulating a sine wave are AM (Amplitude Modulation), FM (Frequency Modulation) and PM (Pulse Modulation). Refer to the  above diagrams to understand how radio waves transmit data). 

What happens when you listen to news from an AM radio station, say an All India Radio medium wave station? The sine wave of the announcer’s voice is combined with the transmitter’s sine wave (carrier wave) to vary its amplitude, and then transmitted. In AM, the amplitude of the sine wave or rather its peak-to-peak voltage changes. FM stations and other wireless technologies including cordless phones, cell phones and WLANs use FM, where based on the information signal, the transmitter’s sine wave frequency changes slightly. In PM, the carrier or sine wave is turned on and off to send data. In its simplest form, it can be a kind of Morse code. (See diagrams for a basic idea of how narrow-band communications work). The receiver in each case is specially tuned to decode information in the carrier wave.

Usage of a carrier wave within a narrow band effectively means limiting amount of data that can be imprinted on to it. Hence the importance of UWB.

Inner workings

UWB uses a kind of pulse modulation. To transfer data, a UWB transmitter emits a single sine wave pulse (called a monocycle) at a time. This monocycle has no data in it. On the contrary, it is the timing between monocycles (the interval between pulses) that determines whether data transmitted is a 0 or a 1. A UWB pulse typically ranges between .2 and 1.5 nanoseconds. If a monocycle is sent early (by 100 pico seconds), it can denote a 0, while a monocycle sent late (by 100 pico seconds) can represent a 1. Now, one pico second = one trillionth of a second. Hence, the quantity of data transmitted is on the high side.

In Pulse Modulation, the sine wave is turned on and off in a particular manner to transmit data

Spacing between monocycles changes between 25 to 1000 nanoseconds on a pulse-to-pulse basis, based on a channel code. A channel code allows data to be detected only by the intended receiver. Since pulses are spaced and timing between pulses depends on the channel, it’s already in encrypted form and is more secure than conventional radio waves.

Now, visualize what happens when you heave a large rock into a small pond. It splashes out the water in one go (as seen with our naked eyes). If captured as a still photo, we’ll see the millions of water droplets that splash out in a fraction of a second and make the splash we see. If ripples are like normal transmission of data between wireless devices (as in blue-tooth or Wi-Fi), UWB promises to be the ‘huge rock’ in data transmission. Through several million monocycles, it uses a wide range of frequencies to transmit large amounts of data in one go.

Only a receiver specifically tuned to the transmitter can receive transmitted data. Hence, it is a comparatively more secure channel for data transmission. Moreover, by using some amount of modulation, sharp spiking and subsequent noise interference with other narrow band devices are reduced to minimal levels. Any other device into whose band UWB pulses might spill over, will at most, feel it as background noise as energy levels of the pulse are low.

THE DIFFERENCE IN THE TRANSMISSION METHODS OF UWB HAS SEVERAL IMPLICATIONS

·         For one thing, because UWB pulses don't actually use a traditional radio signal, called a carrier, UWB transmissions don't take up any of the radio spectrum. Spectrum is limited, and demand for it is growing fast. That's one reason for the FCC interest: UWB would allow a whole new class, and volume, of voice and data communications that, in effect, wouldn't take up any more "space" in the crowded radio spectrum.

·         Second, and partly as a result of the fact that UWB doesn't use a traditional radio signal, UWB transmitters and receivers will be much simpler to build, run and maintain than those in use today. For UWB, you don't need complex radio frequency converters and modulators. We only need a digital method to construct the pulses and modulate them. This can all go on a single chip. One vendor already does this on a chip the size of a penny.

·         Third, because UWB operates in the electronic "noise" area of the spectrum, it requires little power. These systems can use 50 to 70 milliwatts of power.That is one ten-thousandth the power of a cell phone. The low power limits the range, but there are features of pulse transmission and some tuning techniques that can, in effect, extend or maintain the range.

·         In addition, low power and the characteristic wide spread of the pulses means the pulses don't use up already crowded chunks of the radio spectrum, today occupied by 802.11b wireless LANs and Bluetooth devices.

·         Despite the low power, UWB also has greater capacity - higher bandwidth for more users - compared with these other technologies. Time Domain began testing its just-fabricated, second-generation UWB chipset using silicon germanium technology created by IBM. The new chipset can reach 40M bit/sec, compared with just 2.5M bit/sec for the first chipset two years ago. Another start-up, Fantasma Networks, which Pulse-Link acquired , claims to have reached 60M bit/sec.

·         Finally, UWB promises to be highly secure. It's very difficult to filter a pulse signal out of the flood of background electronic noise, and vendors such as Time Domain are encrypting the zeros and ones being transmitted by the pulses.

CELLONICS INCORPORATED DEMONSTRATES UWB AS A NEXT GENERATION WIRELESS TECHNOLOGY

Cellonics Inc. is a world-leading company in the creation of intellectual property in advanced and innovative electronic communication techniques. It holds exclusive licence rights to the patent portfolio of CellonicsTM - the world's first fast, low-cost, low-power and highly robust Carrier-Rate DecodingTM solution. CellonicsTM simplify, speed up and strengthen communication systems. CellonicsTM - Nonlinear, Swift and Simple.

The 12-Mbps/64-microwatt CellonicsTM UWB is a very high-speed, energy-efficient wireless communication system may be realised very simply. In comparison, a Bluetooth device is complex and typically transmits at 1 Mbps with 15 milliwatts of power. Unlike conventional transceivers, a CellonicsTM -based one does not require many subsystems such as a mixer, a PLL, an oscillator, etc. This will lead to a significant reduction in component cost. More importantly, a CellonicsTM -based system is just as robust. Launched in June at CommunicAsia2001, the CellonicsTM technology is a world first.
Cellonics Incorporated Pte Ltd (Cellonics Inc.), the company who invented the biological cell-inspired modem technique CellonicsTM will demonstrate Ultra Wideband (UWB), a next generation wireless method at CommunicAsia2002. The CellonicsTM UWB Wireless Video Demo System, realized with the simple and robust CellonicsTM technology, is unique in the world.

UWB is a pulse-based method of communication now finding fast acceptance and application in the wireless community. Traditional wireless systems such as Wireless LAN or GSM use a carrier (sine wave) method to convey information. A pulse-based system is more robust, especially in a built-up area where multipath interference is likely. Transmission is also more secure as its signal signature is not easily duplicated. A pulse-based system will also have additional smarts such as ranging and object sensing.

Pulse signalling was first applied in radar, hence you will find similar attributes such as object location and transmission security in a UWB system. A UWB system communicates with very low power signals. This means that highly portable and feature-rich wireless devices can be developed. For example, a UWB device the size of a twenty-cent coin may be able to sense a person behind a thin wall or detect water-level in a tank and send that information back.

Low-power signal propagation of the UWB method appeals to communication system designers for another key reason: UWB signals can be sent over existing frequency bands with little or no interference. Existing spectrum space can thus be reused without the need for new frequency allocation. Compared to carrier signals of conventional systems, UWB pulse signals often appear as no-signal or noise. This is especially true in a small-area/home application such as a Wireless Personal Area Network (WPAN) where high-power transmission is not necessary and signals cover only a short range. The fact that UWB signals occupy a wider band also means that high data rates can also be attained.

In the near future, it is not unusual to find a person carrying a wireless device to connect him wirelessly to various data sources and destinations, be it video, audio, Internet, dumb or smart appliances. There isn't a method today that will do all that efficiently and economically. The UWB method is ideal. Built with the simplicity and robustness of the CellonicsTM technology, it becomes an even more  attractive solution.

Indeed, with UWB, a high-speed WPAN with smart appliances can become a reality. Current Wireless LAN and Bluetooth solutions are limited and complex. A UWB wireless network may carry speeds from 100 Mbps to 500 Mbps easily. Devices in this network can be sentient, sending critical status information back to a user.

The CellonicsTM technology represents a giant milestone for digital communications. With it, extremely simple, robust and fast communication transceivers can be built. Inspired by biological cell behaviour and built with principles of Nonlinear Dynamical System or NDS principles, the CellonicsTM technique allows Communication engineers for the first time, to handle digital information efficiently and economically. Its Carrier-rate DecodingTM attribute also allows engineers to build devices that operate at maximum throughput.

There is  also a CellonicsTM UWB Wireless Audio Demo System , this 11.4-Mbps/50-microwatt system employs the simplest CellonicsTM transmitter design - just two basic electronic components. The transmitter is also unique in its Frequency Translation ability.

In recent months, UWB technology has garnered much interest and attention. The Federal Communication Commission (FCC) of the United States allowed the user of UWB will encourage greater development of UWB systems for real-world application. Already, reports are coming out highlighting UWB deployment in near-car avoidance, in search and rescue operations, and in secure field military communications. More and more applications are expected to find UWB wireless expression in the near future. The breakthrough CellonicsTM UWB method can bring this about quickly. With it, the next generation wireless technology is no longer a remote aspiration promising 'wireless everywhere', but is here now for serious consideration.

The nature of UWB communication is such that it is an ideal technology to realise pervasive wireless networking or PWN, the application of wireless technology to everything - not only to networks and devices but appliances as well. It is the epitome of a complete wireless lifestyle. CellonicsTM UWB shows that such a scenario can be realised simply and at speed. In the past, no single method and technology could allow that. Today, we show that it is possible. This opens up a whole new game plan for the Wireless Communications industry. The future of wireless is indeed here.

APPLICATIONS

1) Communications Applications

UWB devices can be used for a variety of communications applications involving the transmission of very high data rates over short distances without suffering the effects of multi-path interference. (FYI, Multipath is the propagation phenomenon that results in signals reaching the receiving antenna by two or more paths, usually due to reflections of the transmitted signal. The ability to time-gate the receiver would allow it to ignore signals arriving outside a prescribed time interval, such as signals due to multipath reflections.) UWB communication devices could be used to wirelessly distribute services such as phone, cable, and computer networking throughout a building or home. These devices could also be utilized by police, fire, and rescue personnel to provide covert, secure communications devices.

2) Positioning Applications

UWB devices can be used to measure both distance and position. UWB positioning systems could provide real time indoor and outdoor precision tracking for many applications. Some potential uses include locator beacons for emergency services and mobile inventory, personnel and asset tracking for increased safety and security, and precision navigation capabilities for vehicles and industrial and agricultural equipment.

3) Radar Applications

UWB technology has been used for some time in Ground Penetrating Radar (GPR) applications and is now being developed for new types of imaging systems that would enable police, fire and rescue personnel to locate persons hidden behind a wall or under debris in crises or rescue situations. UWB imaging devices also could be used to improve the safety of the construction and home repair industries by locating steel reinforcement bars (i.e., re-bar) in concrete, or wall studs, electrical wiring and pipes hidden inside walls. UWB devices could improve automotive safety with collision avoidance systems and air bag proximity measurement for safe deployment. Potential medical uses include the development of a mattress-installed breathing monitor to guard against Sudden Infant Death Syndrome and heart monitors that measure the heart's actual contractions. Some potential home safety uses include intrusion detection systems that are less susceptible to false alarms, and space heaters that turn themselves off when a child comes nearby.

Other applications

The versatile technology, ultra-wideband (UWB), is expected to revolutionize industries such as consumer electronics. Among other things, it could let consumers set up wireless cable TV networks at home, help rescuers find earthquake victims in rubble and greatly improve collision-avoidance systems. Unlike standard wireless systems, which emit radio waves on specific frequencies, UWB devices send out pulses of radio energy, up to 1 billion a second. By precisely timing returning pulses, UWB can sense objects and measure their position far more accurately than traditional radar.It also operates across a wide swath of frequencies, enabling it to run at very high speeds and very low power levels. Thus, unlike narrowband radio waves, UWB signals can penetrate walls more easily.

Ultra-wideband could:

Ø  Help cars avoid collisions by sensing the location and speed of oncoming vehicles. This can greatly enhance accident avoidance.

Ø  Allow police to detect the movements of a hostage taker through a wall.

Ø  Spawn wireless home networks, linking cable set-top boxes or computers. UWB goes a step beyond Bluetooth and other current home wireless systems by transmitting video and other high-bandwidth content. It also can be used to wirelessly download video from a camcorder to a TV.

Ø  Track the precise location of retail products in stores or keep track of military equipment.

Ø  Provide low-cost security systems that could distinguish between, say a pet and an intruder.

However, users of Global Positioning Systems (GPS) say that by traversing many frequencies, UWB might interfere with GPS systems, such as those used by airplanes to navigate over oceans. Satellite-based GPS signals are very sensitive. But FCC officials say UWB emits about as much energy as a laptop PC, and interference is unlikely.

ADVANTAGES

Ø  Doesn’t suffer from multi-path interference.

Ø  High data carrying capacity.

Ø  It need only low power.

Ø  Low energy density.

Ø  Minimum complexity.

Ø  Low cost.

Apart from low-power usage, inherent security and minimal noise generation, UWB doesn’t suffer from multi-path interference (where signals reach the receiver after traveling through two or more paths). Something similar happens when your car is at an intersection surrounded by tall buildings. Your radio might not give a clear reception as it’s receiving both direct signals and those that have bounced off the buildings. Often, the static disappears when you move ahead or backwards. Hence, it can be used in densely built-up places, or where number of users are more than what is supported by Wi-Fi, Blue-tooth etc.

It is immune to interference just as it doesn't interfere with traditional radio signals, so the FCC is considering UWB as an unlicensed service across all frequency bands -- even cellphones and broadcast frequencies. UWB uses one ten thousandth the energy of networks like 802.11b, yet offers the prospect of greater range and greater privacy along with data rates that are presently around 60 megabits-per-second and might eventually hit one gigabit-per-second. UWB is virtually undetectable by traditional radios, since its signals are considered noise -- noise spread across such a wide band as to be beneath the threshold of traditional receivers. UWB uses multipath interference as a form of error correction! What was formerly considered bad is now good. In fact, UWB only works at all because we know precisely where and when to listen. It is based on a complex and very rigidly-structured encoding scheme.

In many ways, UWB is the successor to spread spectrum radio, a World War II technology for splitting a broadcast among many radio frequencies to avoid jamming. Spread spectrum, which was patented in 1942 by actress Hedy Lamar and composer George Antheil (I am not making this up), operates today in every mobile phone. But where spread spectrum used just a few dozen frequencies and used them one at a time, UWB uses every frequency there is, and uses them all at the same time, which means the data-carrying capacity of UWB is enormous.

A UWB phone uses so little power it can remain on for weeks without recharging. And UWB will ultimately be cheaper to make than conventional radios since it is built entirely of commercial grade computer chips and requires no tuning.

As bandwidth is inversely related to pulse duration, the spectral extent of these waveforms can be made quite large. With proper engineering design, the resultant energy densities (i.e., transmitted Watts of power per unit Hertz of bandwidth) can be quite low. This low energy density translates into a low probability of detection (LPD) RF signature. An LPD signature is of particular interest for military applications (e.g., for covert communications and radar); however, an LPD signature also produces minimal interference to proximity systems and minimal RF health hazards, significant for both military and commercial applications.

Among the most important advantages of UWB technology, however, are those of low system complexity and low cost. UWB systems can be made nearly "all-digital", with minimal RF or microwave electronics. Because of the inherent RF simplicity of UWB designs, these systems are highly frequency adaptive, enabling them to be positioned anywhere within the RF spectrum. This feature avoids interference to existing services, while fully utilizing the available spectrum.

DISADVANTAGES

As with any technology, there are always applications that may be better served by other approaches. For example, for extremely high data rate (10’s of Gigabits/second and higher), point-to-point or point-to-multipoint applications, it is difficult today for UWB systems to compete with high capacity optical fiber or optical wireless communications systems. Of course, the high cost associated with optical fiber installation and the inability of an optical wireless signal to penetrate a wall dramatically limit the applicability of optically-based systems for in-home or in-building applications. In addition, optical wireless systems have extremely precise pointing requirements, obviating their use in mobile environments.

UWB is an RF wireless technology, and as such is still subject to the same laws of physics as every other RF technology. Thus, there are obvious tradeoffs to be made in signal-to-noise ratio versus bandwidth, range versus peak and average power levels, etc.

One Argument Against UWB

·         UWB’s necessary bandwidth is from DC to light

• Even if notch filters were used, the radiation within the notched bands would constitute an “emission”
• “Emissions” in radio-astronomy bands are forbidden (ITU Footnote S5.340)
• Therefore, all UWB is illegal

KEY ISSUES FOR UWB

UWB technology is attracting as an ultra fast interface for digital appliances.A number of technical issues involved in getting UWB up and runnig in homes and offices have been uncovered .

They can be broken down into five groups namely

1.    Reducing interference with other radio systems,

2.    Complying with electromagnetic regulations of many nations,

3.    Minimizing erroneous transmissions caused by reflections from walls and objects (multi-path),and

4.    Assuring continuous communication between multiple pieces of equipment (multi-access),

5.    Reducing implementation cost of UWB radio circuitry.

All of these issues will be vital to the success of UWB.

UWB monopolizes a very wide waveband. According to FCC the bandwidth is 7.5GHz,spanning from 3.1 to 10.6GHz.If the full 7.5GHz is used, it would interfere with satellite communications and wireless LAN services at 5GHz.UWB output power is held to a level under that electromagnetic interference (EMI)output of electronic equipment however, so that it should result in only slight noise for other systems using the waveband. Nonetheless, as more and more equipment makes use of  UWB, while the noise generated by a single piece is low, the total noise floor will rise considerably.It is possible that UWB may be tapped for use in notebook PCs as Wireless USBb2.0,in which case a single notebook PC might mount both UWB and a 5GHz WLAN.If both were used at once ,transmission quality would be impaired unless measures are taken to minimize interference by UWB.

 Compliance with regulations of many nations, faces problems because the regulations of each nation are quite different. For example, wavebands that  can be used without licenses in Europe or the US may be unusable in Japan or elsewhere in Asia. Frequency allocations to services such as police, fire, marine safety and the military are all handled individually by each nation, and in many cases are unique. This is difficult to do in consumer electronics, however, which is why the frequency for wireless LAN was carefully set to use  one that was free around the world. Naturally, industry would want to enjoy the same freedom.

Measures to control multi-path fading will require wireless communications technology that can be used in closed spaces such as living rooms. UWB uses extremely short pulses (1ns), and is therefore said to resist  multi-path fading. This is because signals which bounce off the walls or other objects before reaching the receiver are usually delayed enough.For data rates over 100Mbps, however, the pulse interval is even shorter, and the system becomes more susceptible to multi-path effects. The only solution is to adopt a robust modulation scheme.

Multi-access point is needed for real-time transmission such as for video streams. This is fundamentally different from IEEEa/b/g developed for the PC, and is designed to allow multiple UWB systems in a given area to operate simultaneously. It consists of measures to prevent packet collision and rules for transmission timing. UWB systems utilize a combination of frequency division multiplex (FDM) and time division multiple access (TDMA) to accommodate multiple users.

Basic transceiver functions can be provided with a simple circuit in UWB, so the key will be slashing costs for the above four points.

When We Want to Use Wireless to Send:

_ A lot of data

_ Very fast

_ For many users

_ All at once

we can go for UWB

UWB  CHIPset company

Wisair develops and markets a high performance wireless communication chipset solution, based on UWB (Ultra Wide Band) technology. This chipset enables the implementation of low cost, low power, and high bit-rate communication modules and system solutions for the fast emerging home/office connectivity market.

CONCLUSION

UWB is undoubtedly a niche technology which holds promise in a wide area. But, its success depends on scoring against a handful of rival technologies in which companies have invested billions. Those who’ve invested their money will not hasten to consider an upstart rival, even if it offers better services. It seems that UWB will most probably succeed in WPANs as a means of delivering data-intensive applications like video. Imagine downloading the latest blockbuster on your portable player while tanking up at the petrol pump! But, this dream will take at least a year to materialize at the current pace of things.

The U.S. Navy, plans to put a UWB location marker on almost everything it ships overseas, just to keep track of all the stuff and keep it from being stolen.
UWB products will probably begin to hit the market in the next 18 to 24 months. In addition to radios, these products will include radar and electronic positioning devices.

The bottom line is that the FCC's move to make more unlicensed spectrum available is proving to be a huge success for the wireless industry and for consumers. The latest entrant, UWB, is entering an industry and market dramatically matured through the experience of its predecessors Bluetooth and WiFi. If UWB proponents can quickly knock out the issues of standards and interoperability it will allow the powerful forces of Moore's law and economies of scale to start their work early bringing consumers cost effective products within a few short years from today. If the industry has learned from its past mistakes and it looks like it has, UWB is poised for dramatic growth and success in a way not witnessed before for any wireless technology.

The first standards and products based on the UWB will be available in 2005.