Advantageous Solution for Wireless Personal Area Network Using Ultra

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Advantageous solution for wireless personal area network using

ultra-wideband technology (uwb)

Part of the UWB revolution

Author: Dr Gurudutt Sahni

[May. 07, 2007]Ultra-wideband (UWB) technology has gone through some

revolutionary changes this year, including the legalization of the

technology in the US for imaging systems, vehicular radar

systems, and communications and measurement systems.

The allocation of 7.5 GHz worth of new unlicensed spectrum that can be used for

communications and measurement techniques, in particular, has sparked a renewed

interest in both research and development of UWB technology in industry,

universities, and government offices. However, a significant number of challenges

remain for the technology to become ubiquitous. In this paper, a brief status of the

UWB technology will be presented, including international regulatory and standardsthat are currently underway.

Then, some recent results on UWB channel modeling efforts for the indoor multipath

channel are presented, which are critical when designing a high-rate UWB

implementation. Finally, the protocol used in UWB technology and its long list of

applications. Also paper is concern about the disadvantages of this technology.

Ultra-wideband technology is a wireless transmission scheme that occupies a

bandwidth of more than 25 % of a center frequency or more than 1.5 GHz. UWB

technology can bring the mobility of wireless communications to high-speed

interconnects in devices throughout the digital home and office.

Designed for short-range, wireless personal area networks (WPANs), UWB is a

technology that enables wireless connection of multiple devices for transmission of

video, audio and other high-bandwidth data.UWB, short-range radio technology,

complements other longer range radio technologies such as WiFi, WiMAX, and

cellular wide area communications. Its use will be to relay data from a host device to

other devices in the immediate area (up to 10 meters or 30 feet).

A UWB transmitter works by sending billions of pulses across a very wide spectrum

of frequencies several GHz in bandwidth. The corresponding receiver then translatesthe pulses into data by listening to a familiar pulse sequence sent by the transmitter.

Ultra Wideband (UWB) systems transmit signals across a much wider frequency than

conventional systems and are usually very difficult to detect. The amount of spectrum

occupied by a UWB signal, i.e. the bandwidth of the UWB signal is at least 25% of

the center frequency. Thus, UWB's combination of broader spectrum and lower power

improves speed and reduces interference with other wireless spectra.

Why USB vs. Other Technologies?

WiFi

WiFi is an infrastructure-oriented technology and therefore has difficultycommunicating peer to peer. Also it was not designed for streaming audio and video.
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Infrastructure) interference, such as from 802.11a, is present.

OFDM Modulation

The information transmitted on each band is modulated using OFDM. OFDM

distributes the data over a large number of carriers that are spaced apart at precise

frequencies. This spacing provides the orthogonality in this technique, which preventsthe demodulators from seeing frequencies other than their own. The benefits of

OFDM are high-spectral efficiency, resiliency to RF interference, and lower multipath

distortion.

By using OFDM modulation techniques coupled with multibanding, it becomes easier

to collect multipath energy using a single RF chain and allows the receiver to deal

with narrowband interference without having to sacrifice sub bands or data rate.

These advantages relate to the ability to turn off individual tones and also easily

recover damaged tones through the use of forward error-correction coding. In this

system Pulse position modulation is the modulation scheme used to distinguish the

transmission of a digital '1' from a digital '0'.

At the receiver the received signal is correlated with a template signal over the

duration of pulse producing an output. This output is then compared to zero and fromthis it is determined whether a 0 or a 1 was transmitted.

Protocol Used

Ultra-Wideband (UWB) solution provides full wireless connectivity implementing

direct sequence ultra-wideband (DS-UWB) and the IEEE 802.15.3 media access

control (MAC) protocol. The chipset delivers more than 110 Mbps data transfer rate

supporting applications such as streaming video, streaming audio, and high-rate data

transfer at very low levels of power consumption.

Wider Applications of UWB Technology

The concept of a UWB radio spans many different applications and industries and hasbeen coined the "common UWB radio platform." The UWB radio, along with the


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convergence layer, becomes the underlying transport mechanism for different

applications, some of which are currently only wired.

Some of the more notable applications that would operate on top of the common

UWB platform would be wireless universal serial bus (WUSB), IEEE 1394, the next

generation of Bluetooth, and Universal Plug and Play (UPnP). You can see a diagramof this vision in Fig below. This concept has many potential applications since it

creates the first high-speed wireless interconnects. UWB technology offers a

combination of performance and ease of use unparalleled by other interconnects

options available.

Presently, wired USB has significant market segment share as the cable interconnect

of choice for the PC platform. But the need for the cable itself points to convenience

and usability challenges for users. By unleashing peripheral devices from the PC

while still providing the performance users have come to expect from wired USB

connections, wireless USB running on ultra wideband promises to gain significant

volume in the PC peripheral interconnect market segment.

An example application for UWB would be bringing a mobile device like a portable

media player (PMP) in proximity to a content source like a PC, laptop, or external

hard disk drive. Once authentication and authorization is established, the device and

PC can perform bulk data transfer of video files onto the PMP for later vie wing.

Within the consumer electronics industry, there is demand for wirelessly connecting

various devices such as DVDs, HDTVs, set-top boxes (STBs), PVRs, stereos,

camcorders, digital cameras, and other CE devices.Wireless ease of use and data

transfer performance is a key factor for adoption in this category.

For example, wirelessconnectivity would be ideal for a wall-mounted plasma display where, for aesthetic


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reasons, users prefer not to have cables from an STB or Entertainment PC visible. A

variation on this usage model is the ability to stream content to multiple devices

simultaneously. This would allow picture-in-picture functionality or viewing of the

same or different content on multiple viewing devices.

Device Association and SecurityWUSB security will ensure the same level of security as wired USB. Connection-

level security between devices will ensure that the appropriate device is associated

and authenticated before operation of the device is permitted. Higher levels of

security involving encryption should be implemented at the application level.

Processing overhead supporting security should not impose noticeable performance

impacts or add device.

One of the primary objectives when implementing a wireless interconnects is that it is

easy to install and use. Wired connections provide the user with implied expectations,

that is that the device is connected as specified by the user when they install the wire.

When the wire is installed, the user has basic expectations and when theseexpectations do not take place (plug does not fit), there is a known recourse.

Wireless connections, on the other hand, due to environmental characteristics, may

establish connection paths that are not obvious. In fact, it may not be obvious when a

device is connected.

So WUSB devices installed for the first time should automatically install drivers,

security features, and so on and associate with systems that they can interact with. The

concepts of 'turn on and use it' with an easy setup procedure will be employed.

Ultra Wideband Advantages

Extremely difficult to intercept

-Short pulse excitation generates wideband spectra low energy densities

-Low energy density also minimizes interference to other services

Multipath immunityTime-gated detector can excise delayed returns time separation

Commonality of signal generation and processing architectures

-Communications-LPI/D, High Data Rates, Multipath Tolerance

-Radar

-Inherent high precision sub-centimeter ranging

-Wideband excitation for detection of complex, low RCS targets

-Geolocation/Positioning

-Sub-centimeter resolution using pulse leading edge detection

Low Cost

-Nearly all-digital architecture

-Ideal for microminiaturization into a chipset

-Frequency diversity with minimal hardware modifications

UWB Applications


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Tactical Handheld & Network LPI/D Radios

Non-LOS LPI/D Groundwave

Communications

LPI/D Altimeter/Obstacle Avoidance Radar

Intrusion Detection RadarsPrecision Geolocation Systems

Proximity FuzesLPI/D Wireless Interc

High Speed (20+ Mb/s) WLANs on Systems

Altimeter/Obstacle Avoidance Radars (commercial aviation)

Collision Avoidance Sensors

Tags (Intelligent Transportation Systems, Electronic Signs, Smart Appliances)

Industrial RF Monitoring Systems

Disadvantages

The major problem is possible interference with global positioning satellite (GPS) asit has a large number of users. It is also seen as a threat to aircraft guidance system

and also to astronomy as the equipment used are very sensitive to interference.

Conclusion

UWB is in early stages of devlopements. It is proving its worth in various fields with

advantages like high bit rate, multimedia connectivity to wireless personal area

network. World is on the verge of freedom from wires. UWB technology offers a

solution for band-width, cost, power consumption, and size requirements of next

generation consumer electronics.

A number of UWB components and system are in testing phase and will be releasing

in near future. UWB has been redefined as a high data rate (480+ Mbps), short-range

(up to 20 meters) technology that specifically addresses emerging applications in the

consumer electronics, personal computing and mobile device markets. When

compared to other existing and nascent technologies capable of providing wireless

connectivity, the performance benefits of UWB are compelling.

References

[1]. Robert Tseng, Jacob Kuo. Ultra wideband Technology (UWB), EE206A Spring

2002

[2] M.Z. Win, Ultra-Wide Bandwidth Spread Spectrum Tech- sis, Electrical

Engineering, University of Southern California,[3].www.intel.com/technology/comms/uwb

[4]. www.palowireless.com/uwb/tutorials.asp

[5]. www.ultrawidebandplanet.com/technology/

[6]. www.multispectral.com/history.html

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Advantageous Solution for Wireless Personal Area Network Using Ultra

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