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	OFDM Tutorial
		The benefits of OFDM are high spectral efficiency, resiliency to RF interference, and lower multi-path distortion.
		OFDM is sometimes called multi-carrier or discrete multi-tone modulation.
		VOFDM (Vector OFDM) uses the concept of MIMO technology and is also being developed by Cisco Systems.
	www.wave-report.com /tutorials/OFDM.htm (526 words)

	Radio-Electronics.Com :: OFDM Tutorial
		OFDM has been adopted in the Wi-Fi arena where the 802.11a standard uses it to provide data rates up to 54 Mbps in the 5 GHz ISM (Industrial, Scientific and Medical) band.
		In terms of the equipment to be used the high peak to average ratio of multi-carrier systems such as OFDM requires the RF final amplifier on the output of the transmitter to be able to handle the peaks whilst the average power is much lower and this leads to inefficiency.
		The concept of this form of OFDM is that it uses a degree of spacing between the channels that is large enough that any frequency errors between transmitter and receiver do not affect the performance.
	www.radio-electronics.com /info/cellulartelecomms/ofdm/ofdm.php (989 words)

	Multiuser OFDM
		OFDM allows for a high spectral efficiency as the carrier power, and modulation scheme can be individually controlled for each carrier.
		OFDM can be applied in a multiuser application producing a highly flexible, efficient communications system.
		This paper presents multiuser OFDM in a more general form and outlines some of the potential techniques that could be used to make it a highly efficient and reliable communication system.
	www.skydsp.com /publications/MultiuserOFDM/index.htm (2686 words)

	CommsDesign - Enabling Fast Wireless Networks with OFDM
		OFDM exhibits lower multi-path distortion (delay spread), since the high-speed composite's sub-signals are sent at lower data rates.
		With 802.11a OFDM modulation, the binary serial signal is divided into groups (symbols) of one, two, four, or six bits, depending on the data rate chosen, and converted into complex numbers representing applicable constellation points.
		OFDM's high degree of spectral efficiency resiliency to interference and multipath distortion, and existing inclusions in the leading higher rate WLAN standards, provides a strong base for the development of newer broadband wireless networks.
	www.commsdesign.com /story/OEG20010122S0078 (2081 words)

	Gaining Spectral Efficiency with OFDM- Developer Zone - National Instruments (Site not responding. Last check: 2007-10-28)
		OFDM spreads the data to be transmitted over a large number of carriers - typically in the range of 50 to 1000, but sometimes in thousands, for example, DVB-T has options for using either 1705 or 6817 carriers.
		The OFDM signal is formed by modulating these orthogonal carriers using a sequence of symbols generated by mapping the input bit stream into complex symbols (IQ symbols) based on an m-ary constellation.
		OFDM is a modulation technique which is widely being used for high speed data transfer.
	zone.ni.com /devzone/cda/tut/p/id/3370 (2628 words)

	Orthogonal Frequency Division Multiplexing (OFDM)
		OFDM signals typically have a time guard of 800 ns, however, which provides very good performance on channels having delay spreads up to 250 ns.
		With 802.11a OFDM modulation, the binary serial signal is divided into groups (symbols) of 1, 2, 4, or 6 bits, depending on data rate chosen, and converted into complex numbers representing applicable constellation points.
		OFDM’s high degree of spectral efficiency, resiliency to interference and multi-path distortion, and existing inclusions in the leading higher rate wireless LAN standards, provides a strong based for the development of newer broadband wireless networks.
	www.wireless-nets.com /papers/wireless_lan_ofdm.htm (1654 words)

	IEC: OFDM for Mobile Data Communications
		OFDM, or multitone modulation as it is sometimes called, is presently used in a number of commercial wired and wireless applications.
		For wireless, OFDM is the basis for several television and radio broadcast applications, including the European digital broadcast television standard, as well as digital radio in North America.
		OFDM enables the creation of a very flexible system architecture that can be used efficiently for a wide range of services, including voice and data.
	www.iec.org /online/tutorials/ofdm (373 words)

	J.P. Linnartz: OFDM
		OFDM is significantly less sensitive to intersymbol interference, because a special set of signals is used to build the composite transmitted signal.
		OFDM is used in HIPERLAN Phase II, which supports 20 Mbit/s in propagation environments with delay spreads up to 1 msecond.
		The different influences of the radio front-end on OFDM communication performance are detailed in the next chapters as well as many OFDM practical problems related to non-linear power amplifiers.
	wireless.per.nl /wireless/mccdma/ofdm.htm (485 words)

	All About OFDM from SSS Online and Pegasus Technologies
		OFDM stands for Orthogonal Frequency Division Multiplexing and is a modulation technique for transmitting large amounts of digital data over a radio wave.
		OFDM and MC-CDMA for Broadband Multi-User Communications, WLANs and Broadcasting, by Lajos Hanzo, M. Münster, B.J. Choi, Thomas Keller.
		MultiBand OFDM Alliance —: this is the group that is involved in a major standards battle on Ultra wideband.
	www.sss-mag.com /ofdm.html (2401 words)

	Orthogonal frequency-division multiplexing - Wikipedia, the free encyclopedia
		OFDM is invariably used in conjunction with channel coding (forward error correction), and almost always uses frequency and/or time interleaving.
		OFDM in its primary form is considered as a digital modulation technique, and not a multi-user channel access technique, since it is utilized for transferring one bit stream over one communication channel using one sequence of OFDM symbols.
		OFDM is used in ADSL connections that follow the G.DMT (ITU G.992.1) standard, in which existing copper wires are used to achieve high-speed data connections.
	en.wikipedia.org /wiki/OFDM (4132 words)

	BreezeACCESS OFDM Broadband Wireless System
		Leveraging the excellent multipath resistance capabilities of OFDM technology, BreezeACCESS OFDM enables operation in near and non-line-of-sight (NLOS) conditions, which enable Operators to reach a previously inaccessible and broader segment of the subscriber population, with fewer Base Stations.
		BreezeACCESS OFDM provides an instant and independent infrastructure, which is immediately deployable with lower infrastructure construction and operating costs than any other solution on the market.
		OFDM enabled high base station data capacity - 72/192 Mbps can be achieved over typical frequency allocations of 10.5/28 MHz respectively.
	www.airlinx.com /products.cfm/product/3-5-409.htm (708 words)

	VLSI implementation of OFDM modem
		OFDM is a multi-carrier system where data bits are encoded to multiple sub-carriers, while being sent simultaneously.
		OFDM is a multi-carrier system where data bits are encoded to multiple sub-carriers.
		The OFDM is therefore able to provide higher data rate for the same BW OFDM is fast gaining popularity in broadband standards and highspeed wireless LAN.
	www.us.design-reuse.com /articles/article10358.html (2823 words)

	eCLIPS - Design Guide for 'OFDM'
		Orthogonal Frequency Division Multiplexing (OFDM) is a wireless technology patented in 1970 that runs on the principle of transmitting data by dividing the data stream into multiple parallel bit streams that have a much lower bit rate and using these sub-streams to modulate several carriers.
		Although OFDM has been chosen as the physical layer standard for a diversity of important systems, the theory, algorithms, and implementation techniques remain subjects of current interest.
		OFDM is a key technology for beyond 3G communications, promising robust, high capacity, high speed wireless broadband multimedia networks.
	www.eg3.com /eclips/html/design-guide/mobile_ofdm_blank.html (670 words)

	Technologies Beyond 3G - Flash OFDM from Flarian
		While CDMA and UMTS increase the capacity and spectral efficiency viewpoints as compared to 2G and 2.5G wireless networks, there are still issues with these packet networks when applied to wireless data.
		The technology uses OFDM, in which a single channel is divided into several subchannels, each at a different frequency.
		OFDM, unlike traditional FDM, uses signal modulation and demodulation techniques, as well as the orthogonal placement of adjacent channels, to minimize interference.
	www.mobileinfo.com /3G/Beyond3G_FlashOFDM.htm (573 words)

	OFDM Spotlight - a collection of OFDM resources on RF Design - ofdm, orthogonal frequency division multiplexing
		Orthogonal Frequency-Division Multiplexing (OFDM) is based upon the principle of frequency-division multiplexing, but is utilized as a digital modulation scheme.
		The effects of these same impairments on an OFDM signal, however, can be quite different....
		Evaluating the impact of pulsed phase noise on 802.11a/g OFDM transmit performance
	rfdesign.com /next_generation_wireless/ofdm (460 words)

	OFDM, VOFDM, COFDM, Orthogonal Frequency Division Multiplexing
		OFDM Receivers for Broadband-Transmission OFDM and the orthogonality principle, The general problem: Data transmission over multipath channels, Single carrier approach, Multi carrier approach, Orthogonal Frequency Division Multiplexing, An OFDM receiver for DVB-T, Tasks of the inner receiver and receiver structure, Channel estimation for OFDM, Performance of the complete receiver...
		OFDM Tutorial Frequency division multiplexing (FDM) is a technology that transmits multiple signals simultaneously over a single transmission path, such as a cable or wireless system.
		Orthogonal FDM's (OFDM) spread spectrum technique distributes the data over a large number of carriers that are spaced apart at precise frequencies.
	www.palowireless.com /ofdm/tutorials.asp (585 words)

	What is orthogonal frequency-division multiplexing? - a definition from Whatis.com - see also: OFDM
		- Orthogonal frequency-division multiplexing (OFDM) is a method of digital modulation in which a signal is split into several narrowband channels at different frequencies.
		In some respects, OFDM is similar to conventional frequency-division multiplexing (FDM).
		OFDM is used in European digital audio broadcast services.
	searchnetworking.techtarget.com /sDefinition/0,,sid7_gci523666,00.html (251 words)

	OFDM: Old Technology for New Markets
		Now, with the advent of Orthogonal Frequency Division Multiplexing (OFDM) (define), wireless standards like IEEE 802.11a and 802.11g (define) are moving the real-world wireless LAN speed limit to 50Mbps and beyond.
		While OFDM has been around for more than 40 years, and has shown up in such disparate places as asymmetric DSL (ADSL) (define) broadband and digital audio and video broadcasts, it's only now becoming popular for wireless communications.
		Typically, OFDM, a spread-spectrum technology that gives wireless networking a new physical (PHY) layer, is implemented in embedded chipsets made up of radio transceivers, Fast Fourier Transform (FFT) processors, system input/output (I/O), serial to parallel and back again translators and OFDM logic.
	www.wi-fiplanet.com /tutorials/article.php/1500641 (1432 words)

	Research Project OFDM Concepts for Wireless Indoor Communications at the Department of Telecommunications at the ...
		Research Project OFDM Concepts for Wireless Indoor Communications at the Department of Telecommunications at the University of Bremen
		The main advantage of MC technique is a longer symbol duration by factor N (N: number of subcarrier).
		OFDM is a special case of the multicarrier technique.
	www.ant.uni-bremen.de /research/wlan/ofdm.html (252 words)

	OFDM for Wireless LAN (IEEE 802.11a)
		The focus is on OFDM modulation and demodulation, training and communication through a fading multipath channel.
		Prior to outputting the OFDM symbols with guard intervals, the OFDM modulator generates the IEEE 802.11a specfied training sequence.
		The real part of the OFDM packets is plotted as are the real and imaginary parts of the correlator output.
	www.ee.duke.edu /~sasan/ofdm.html (1283 words)

	IAF - Gigabit MIMO OFDM Testbed
		The OFDM transmission technique is ideally suited for combination with MIMO signal processing due to its robustness against multipath propagation and frequency selective radio channels.
		The extensive experience from recent projects (for example broadband OFDM testbed) was a substantial presupposition for the succesful development of the MIMO OFDM testbed.
		The general concept of the MIMO OFDM testbed is depicted in the diagrams below.
	www.iaf-bs.de /projects/gigabit-mimo-ofdm-testbed.en.html (454 words)

	Qualcomm Flarion Technologies - Qualcomm Flarion Technologies
		Qualcomm Flarion Technologies (QFT) is the developer and provider of the wireless industry's first and only fully mobile OFDM offering for operators — FLASH-OFDM®.
		Qualcomm acquired Flarion Technologies in January 2006 to expand its already extensive portfolio of OFDMA intellectual property and enhance Qualcomm's industry-leading RandD organization with expertise in OFDMA technology and products.
		“Flarion's expert engineering staff provides a significant addition to the resources that we have dedicated over the years to develop OFDM and OFDMA technologies.
	rd.business.com /index.asp?epm=s.1&bdcq=OFDM&bdcr=2&bdcu=http://www.flarion.com/&bdcp=&partner=2662601&bdcs=nwuuid-2662601-6E17BBB2-FE5B-A855-6DD8-EC53BBE49C03-ym (137 words)

	Building future networks with MIMO and OFDM
		OFDM is a modulation technique, depicted in the following graphic, which uses many sub-carriers, or tones, to carry a signal.
		OFDM has some key advantages over the common wireless access technology known as CDMA, which is used in many of today’s 3G cellular networks.
		In this way, MIMO and OFDM are key technologies for enabling the wireless industry to deliver on the vast potential and promise of wireless broadband.
	telephonyonline.com /wireless/technology/mimo_ofdm_091905 (1603 words)

	Welcome to SkyDSP, OFDM systems, telemetry, software radio
		OFDM allows different modulations to be used on each of the carriers in the system.
		This paper is an introduction to the use of OFDM in multiuser applications and some of the potential techniques that can be used to make a multiuser OFDM system a highly robust, high spectral efficient communication system.
		OFDM waveforms tend to have a high Peak to Average Power Ratio (PAPR).
	www.skydsp.com /publications (276 words)

	BDTI Services -- Communications Benchmark
		The BDTI Communications Benchmark (OFDM)™ is an application-oriented benchmark based on an orthogonal frequency division multiplexing (OFDM) receiver, as shown in the block diagram below.
		BDTI introduced the BDTI Communications Benchmark (OFDM) in 2001 as a means to evaluate application performance and complex architectures.
		The BDTI Communications Benchmark (OFDM) is designed to enable assessment and comparison of a wide range of processors including digital signal processors, general-purpose processors, FPGAs, and configurable processors.
	www.bdti.com /products/services_comm_benchmark.html (573 words)

	Introduction (Site not responding. Last check: 2007-10-28)
		Orthogonal Frequency Division Multiplexing (OFDM) is a method that allows to transmit high data rates over extremely hostile channels at a comparable low complexity.
		OFDM has been chosen as the transmission method for the European radio (DAB) and TV (DVB-T) standard.
		The OFDM project at the ISS is concerned with the development and evaluation of receiver structures for OFDM.
	www.ert.rwth-aachen.de /Projekte/Theo/OFDM/node1.html (231 words)

	What is OFDM? - A Word Definition From the Webopedia Computer Dictionary
		OFDM works by splitting the radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver.
		OFDM reduces the amount of crosstalk in signal transmissions.
		The construction of a facility and silent sources of RF interference impact the propagation of radio waves, often in odd ways.
	www.webopedia.com /TERM/O/OFDM.html (140 words)

	OFDM's New Uses
		We can expect to see a war between OFDM and CDMA for dominance of the mobile broadband wireless access market in the next five to ten years.
		But OFDM "shares" bandwidth completely differently than both CDMA and Time Division Multiple Access (TDMA), so it's far from a "drop-in" replacement for those technologies." Practically speaking, "There really isn't much of a battle here (today) since CDMA has more than 150 million worldwide subscribers and OFDM has none.
		Certainly OFDM works well for packet-based data, but the jury is still out with large numbers of voice customers.
	www.wi-fiplanet.com /tutorials/article.php/1502361 (887 words)

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