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Topic: Intersymbol interference

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	Intersymbol interference - Wikipedia, the free encyclopedia
		In a digital transmission system, distortion of the received signal, which is manifested in the temporal spreading and consequent overlap of individual pulses to the degree that the receiver cannot reliably distinguish between changes of state, i.e.
		Intersymbol interference attributable to the statistical nature of quantum mechanisms sets the fundamental limit to receiver sensitivity.
		Intersymbol interference may be measured by eye patterns.
	en.wikipedia.org /wiki/Intersymbol_interference (475 words)

	CommsDesign - ADSL Technology Explained, Part 1: The Physical Layer (Site not responding. Last check: 2007-09-17)
		Interference that is short in duration but of a large magnitude is known as impulse noise.
		The effect of intersymbol interference is removed by discarding the cyclic prefix at the receiver.
		The ability to remove the effect of intersymbol interference by discarding the cyclic prefix is one of the advantages of having a long symbol period.
	www.commsdesign.com /csdmag/sections/feature_article/OEG20010221S0082 (3101 words)

	Coordinated Science Laboratory
		But one type of interference, known as intersymbol interference, can attack and disrupt these signals as they carry increasing amounts of data or travel for extremely long distances.
		Intersymbol Communications received its first round of financing in June of 2001 and its second round in August of 2002.
		Intersymbol's answer, on the other hand, is an electronic solution, which is much more economical.
	www.csl.uiuc.edu /research/light2.asp (658 words)

	Definition: intersymbol interference (Site not responding. Last check: 2007-09-17)
		In a digital transmission system, distortion of the received signal, which distortion is manifested in the temporal spreading and consequent overlap of individual pulses to the degree that the receiver cannot reliably distinguish between changes of state, i.e.
		Note 1: At a certain threshold, intersymbol interference will compromise the integrity of the received data.
		Note 2: Intersymbol interference attributable to the statistical nature of quantum mechanisms sets the fundamental limit to receiver sensitivity.
	www.its.bldrdoc.gov /fs-1037/dir-019/_2849.htm (148 words)

	Systems and methods for multicarrier modulation using multi-tap frequency-domain equalizer and decision feedback - ...
		At the other end of the communication path, the N time domain values are accumulated and transformed via a Fourier transform to recover the original M symbols after equalization of the transformed data to correct for the attenuation and phase shifts that may have occurred in the channels.
		Alternatively, the disclosed intersymbol interference reduction system may be implemented partially or fully in hardware using standard logic circuits or VLSI design.
		The intersymbol interference reduction system can also be implemented by physically incorporating the system and method into a software and/or hardware system, such as the hardware and software systems of a communications transceiver.
	www.freepatentsonline.com /6760373.html (3659 words)

	Orthogonal frequency-division multiplexing - Wikipedia, the free encyclopedia
		where the symbols are relatively long compared to the channel time characteristics) suffer less from intersymbol interference caused by multipath, it is advantageous to transmit a number of low-rate streams in parallel instead of a single high-rate stream.
		Since the duration of each symbol is long, it is feasible to insert a guard interval between the OFDM symbols, thus eliminating the intersymbol interference.
		Intersymbol interference can be avoided if the multipath time-spreading (the time between the reception of the first and the last echo) is shorter than the guard interval, i.e.
	en.wikipedia.org /wiki/COFDM (4132 words)

	System and method for self-adaptive maximum likelihood sequence detection - Patent 6134277
		It is a further object of the present invention that the aforesaid improved technique determine the transmitted symbol sequence without using a training sequence to estimate the channel coefficient parameters that are used to model the unknown intersymbol interference (ISI).
		As discussed, dynamic programming techniques for resolving intersymbol interference (ISI), such as Viterbi algorithms, are not feasible for implementing sequential self-adaptive equalization techniques, where the channel coefficients are unknown.
		As is understood to one skilled in this art, a larger value of L implies a greater length of intersymbol interference for analysis.
	www.freepatentsonline.com /6134277.html (5260 words)

	Demodulation of Cochannel QAM Signals
		This paper proposes a method for improving the performance of a single-input QAM demodulator in the face of cochannel QAM interference by jointly estimating the desired (primary) signal and the interfering (secondary) signal.
		The specific cochannel interference scenario under examination was generated by summing a simulated QPSK signal with a second cochannel QPSK signal and white Gaussian noise.
		The SIR of the primary (desired) signal with respect to the secondary (interference) signal was 7 dB and the SNR of the primary signal was 30 dB.
	www.appsig.com /products/813f.htm (3108 words)

	An Adaptive Nulling System for Digital Microwave Radio
		Reference [1] introduced the use of the constant modulus algorithm for adaptive beamforming in the presence of multipath interference.
		This eliminates not only the residual interference, but also notch induced ISI from the equalizer output and results in a much cleaner output polar plot, which is shown in Figure 7(c).
		The hybrid system is capable of nulling directional cochannel or multipath interference while equalizing residual intersymbol interference not removed by the combiner.
	www.appsig.com /products/813c.htm (2882 words)

	CiteULike: Linear unbiased data estimation in mobile radio systems applying CDMA (Site not responding. Last check: 2007-09-17)
		In mobile radio systems applying CDMA, multipath propagation leads to intersymbol interference (ISI) and together with time variance, to cross interference between the signals of different users regardless of whether the user codes are chosen orthogonal or not.
		A linear unbiased data estimation algorithm is presented that eliminates both ISI and cross interference perfectly by jointly detecting the different user signals, leading to unbiased estimates of the transmitted data symbols.
		By theoretical analysis and simulation, the performance of the linear unbiased data estimation algorithm is examined under the assumption that the radio channel impulse responses are known at the receiver.
	www.citeulike.org /user/chenjinhui/article/802844 (376 words)

	Method and apparatus for compensating for intersymbol interference in a received signal - US Patent 6693984 (Site not responding. Last check: 2007-09-17)
		Method and apparatus for compensating for intersymbol interference in a received signal
		A method and arrangement are proposed for compensating for intersymbol interference (ISI) in a multi-carrier transmission system.
		Compensation is based on the generation of an estimate of the ISI transient tail generated between consecutively transmitted symbols and subtracting this tail from the received signals.
	www.patentstorm.us /patents/6693984.html (364 words)

	Untitled Document
		The material is divided into three major chapters, one covering the Interference Mitigation methodology, the other Interference Suppression techniques and the last one contains examples of practical cancellers, which can be implemented in real world designs.
		Interference is considered, in this context, as any signal which may cause unacceptable information signal reception.
		Thus, we analyze the interfered with systems under the influence of additive noise, co-channel interference, adjacent channel interference, intermodulation, intersymbol interference, non-linearities, as well as fading.
	www.ieeevtc.org /vtc2003fall/tutorial8.html (405 words)

	Numerically Efficient Fourier-Based Technique for Calculating Error Probabilities with Intersymbol Interference
		We propose a numerically efficient technique for calculating the probability of symbol error for arbitrary coherent modulation schemes in the presence of intersymbol interference (ISI) and additive noise.
		The probability of error is formulated in terms of an inverse Fourier transform of the windowed characteristic function of the random variable representing the interfering symbols and the noise process.
		Metzger, "On the probability density of intersymbol interference," IEEE Trans.
	www.comsoc.org /comm/private/1997/jun/629_45comm06-reuter.html (300 words)

	DESIGN AND PERFORMANCE OF MULTICARRIER CDMA SYSTEM IN FREQUENCY SELECTIVE RAYLEIGH FADIND CHANNEL
		As MC-CDMA is developed as a combination of DS-CDMA and OFDM (Orthogonal frequency division Multiplexing), the need for OFDM to increase capacity and to reduce intersymbol interference on binary data communication system is also discussed.
		This phase shift in the frequency domain can be represented as a sync function.As sync extends upto infinity,there is a huge probability of intersymbol interference between adjacent bits.This scheme is also not suitable for frequency diversity.The period of the sync nulls are separated at a distance of symbol frequency.
		The intersymbol interference can be removed by introducing certain guard bands between the subcarriers.
	www.cs.wright.edu /~ashaw/ee745/proposals/paul.htm (1246 words)

	Digital Distortion Caused by Traveling-Wave-Tube Amplifiers
		In particular, intersymbol interference caused by the TWTA becomes a major consideration for accurate data detection at the receiver.
		Experimentally investigating the effects of the physical TWTA on intersymbol interference would be prohibitively expensive, as it would require manufacturing numerous amplifiers in addition to acquiring the required digital hardware.
		In addition, digital signal performance, including intersymbol interference, was compared using direct data input into the MAFIA model and using the system-level analysis tool SPW for several higher order modulation schemes.
	www.grc.nasa.gov /WWW/RT2001/5000/5620kory.html (487 words)

	Arrangement for combating intersymbol interference and noise (US4905254) (Site not responding. Last check: 2007-09-17)
		An arrangement for combating intersymbol interference and noise, which are introduced into a data signal (a
		Apparatus for combating intersymbol interference and noise which are introduced into a data signal transmitted at a symbol rate 1/T by a dispersive transmission channel with a transfer characteristic, the transfer characteristic having a presumed main character, said apparatus comprising:
		K. Wesolowski, "On the Performance and Convergence of the Adaptive Canceller of Intersymbol Interference in Data Transmission", IEEE Trans.
	www.delphion.com /details?&pn10=US04905254 (492 words)

	Fiber Optic Communications for the Premises Environment by Dr. Kenneth S. Schneider PhD. Chapter 1.
		The term interference is used when this extraneous signal has a more deterministic structure-like 60-cycle hum on a TV set.
		In particular, to lessen intersymbol interference the bandwidth of the Transmission Medium must get larger in relation to the Source's generated bit rate, R BPS.
		However, the effect of noise and interference originating outside the link is far less than with competing choices for the Transmission Medium, candidates like shielded or unshielded twisted pair cable or coaxial cable or free space microwave radio.
	www.telebyteusa.com /foprimer/foch1.htm (5325 words)

	GSM Physical Layer Modulation (Site not responding. Last check: 2007-09-17)
		It happens that with lower time-bandwidth products the pulse is spread over a longer time, which can cause intersymbol interference.
		In the GSM standard a time-bandwidth product of 0.3 was chosen as a compromise between spectral efficiency and intersymbol interference.
		With this value of WTb, 99% of the power spectrum is within a bandwidth of 250 kHz, and since GSM spectrum is divided into 200 kHz channels for multiple access, there is very little interference between the channels [2].
	www.eecg.toronto.edu /~nazizi/gsm/modulation/index.html (749 words)

	Intellectual Property Office - Technology Detail
		The need for blind equalization (deconvolution) arises in a number of areas such as digital data transmission, echo cancellation, seismic deconvolution and image restoration.
		The success of high data rate transmission over bandlimited channels depends critically on the ability of the receiver to adequately remove intersymbol interferences (ISI) without a "training sequence".
		Thus the key to the development of a blind equalizer is to design the rule of adjustment such that the ISI is minimized with no knowledge of the specific values of the channel input, only the channel output.
	www.ipo.uc.edu /index.cfm?fuseaction=technologies.results&item_number=250 (211 words)

	CHAPTER 2
		The characteristic (2.7) is the only meeting the conditions for no intersymbol interference because, in accord with the sampling theorem, being bandlimited at the Nyquist frequency (minimum bandwidth) is uniquely determined by the samples
		Once, because it corresponds to no symbol interference, and twice, because it is not physically realizable.
		To have no intersymbol interference, the equivalent Nyquist bandwidth characteristic which can be obtained in this way must be rectangular.
	www.dsp.pub.ro /leonardo/ipa/Chapter2/Level1/SubChapter2.4/Subchapter2_4.htm (828 words)

	Mismatched Decoding of Intersymbol Interference Using a Parallel Concatenated Scheme (Site not responding. Last check: 2007-09-17)
		A turbo-type scheme that uses parallel concatenation and soft-output iterative detection is proposed for transmission over linear intersymbol interference channels.
		Balachandran and J. Anderson, "Decoding of intersymbol interference channels using parallel concatenation and turbo detection," in Proc.
		Douillard et al., "Iterative correction of intersymbol interference: turbo equalization," Eur.
	www.comsoc.org /sac/private/1998/feb/255_16sac02-balachandran.html (451 words)

	Raised Cosine FIR Filter Design with ScopeFIR
		Raised Cosine filters are commonly used in digital data communication systems to limit Intersymbol Interference (ISI).
		This is due to the number of filter taps we chose (47); we could have used more taps if more attenuation was desired, but that would have resulted in more calculations and more delay through the filter; in this application, 47 taps was deemed to be a good compromise.
		This illustrates that even with the correct filter, Intersymbol Interference can occur if the symbol sampling synchronization is not correct.
	www.iowegian.com /fir/tutor/rcfilt.htm (689 words)

	SSG Seminar Abstract (Site not responding. Last check: 2007-09-17)
		For such paradigms the intersymbol interference is also two-dimensional.
		This interference invalidates assumptions in the Viterbi and related algorithms necessitating novel decoding strategies.
		We describe several approaches for the design of encoding and decoding for data storage systems that have two-dimensional (2D) intersymbol interference (ISI).
	ssg.mit.edu /cal/abs/2006_spring/nsingla060601.shtml (248 words)

	ActionFront Data Recovery Research
		This can expand the amount of data that must be written by about one percent to as much as 12.5%, depending on the RLL code used.
		To ensure that the waveform is close to this target, a combination of fixed and adaptive filtering is applied to the readback signal.
		That is, it is less likely that a common pattern, (e.g., a control character, space, carriage return) that might be a difficult pattern to detect will appear over and over, thereby degrading the bit error rate.
	www.actionfront.com /ts_whitepaper.asp (4359 words)

	Xiang-Gen Xia: Modulated Coding for Intersymbol Interference Channels (Signal Processing and Communications, 6) (Site not responding. Last check: 2007-09-17)
		Xiang-Gen Xia: Modulated Coding for Intersymbol Interference Channels (Signal Processing and Communications, 6)
		Xiang-Gen Xia, "Modulated Coding for Intersymbol Interference Channels (Signal Processing and Communications, 6)", Marcel Dekker, 01 October, 2000.
		Other subject areas related to Modulated Coding for Intersymbol Interference Channels (Signal Processing and Communications, 6) (possibly beyond the scope of this CDMA Glossary) include: Coding Theory, Digital Communication Engineering, Electromagnetic interference, Engineering - Electrical & Electronic, General, Modulation (Electronics), Programming - Systems Analysis & Design, Science/Mathematics, Signal processing, Technology, Technology & Industrial Arts, Telecommunications.
	www.argospress.com /Resources/cdma/book-0824704592.htm (213 words)

	vsevcosmos: Detection of Markov Random Fields on Two-Dimensional Intersymbol Interference Channels. [cs.IT/06091
		vsevcosmos: Detection of Markov Random Fields on Two-Dimensional Intersymbol Interference Channels.
		Detection of Markov Random Fields on Two-Dimensional Intersymbol Interference Channels.
		We present a novel iterative algorithm for detection of binary Markov random fields (MRFs) corrupted by two-dimensional (2D) intersymbol interference (ISI) and additive white Gaussian noise (AWGN).
	vsevcosmos.livejournal.com /20488771.html (216 words)

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