Showing papers on "Bit error rate published in 1990"
01 Apr 1990
TL;DR: A multiuser detection strategy for coherent demodulation in an asynchronous code-division multiple-access system is proposed and analyzed, showing that the two-stage receiver is particularly well suited for near-far situations, approaching performance of single-user communications as the interfering signals become stronger.
Abstract: A multiuser detection strategy for coherent demodulation in an asynchronous code-division multiple-access system is proposed and analyzed. The resulting detectors process the sufficient statistics by means of a multistage algorithm based on a scheme for annihilating successive multiple-access interference. An efficient real-time implementation of the multistage algorithm with a fixed decoding delay is obtained and shown to require a computational complexity per symbol which is linear in the number of users K. Hence, the multistage detector contrasts with the optimum demodulator, which is based on a dynamic programming algorithm, has a variable decoding delay, and has a software complexity per symbol that is exponential in K. An exact expression is obtained and used to compute the probability of error is obtained for the two-stage detector, showing that the two-stage receiver is particularly well suited for near-far situations, approaching performance of single-user communications as the interfering signals become stronger. The near-far problem is therefore alleviated. Significant performance gains over the conventional receiver are obtained even for relatively high-bandwidth-efficiency situations. >
1,430 citations
Journal Article•
TL;DR: In this paper, the authors consider an asynchronous code-division multiple access (CDMA) environment where the receiver has knowledge of the signature waveforms of all the users and compare detectors by their worst case bit error rate in a low background noise near-far environment.
Abstract: We consider an asynchronous code-division multiple-access environment in which the receiver has knowledge of the signature waveforms of all the users. Under the assumption of white Gaussian background noise, we compare detectors by their worst case bit error rate in a low background noise near-far environment where the received energies of the users are unknown to the receiver and are not necessarily similar.
1,008 citations
TL;DR: The authors explore suboptimal demodulation schemes which exhibit a low order of complexity while not exhibiting the impairment of the conventional single-user detector, and show that there exists a linear detector whose bit-error-rate is independent of the energy of the interfering users.
Abstract: Consideration is given to an asynchronous code-division multiple-access environment in which receiver has knowledge of the signature waveforms of all the users. Under the assumption of white Gaussian background noise, the authors compare detectors by their worst case bit error rate in a near-far environment with low background noise, where the received energies of the users are unknown to the receiver and are not necessarily similar. Conventional single-user detection in a multiuser channel is not near-far resistant, and the substantially higher performance of the optimum multiuser detector requires exponential complexity in the number of users. The authors explore suboptimal demodulation schemes which exhibit a low order of complexity while not exhibiting the impairment of the conventional single-user detector. It is shown that there exists a linear detector whose bit-error-rate is independent of the energy of the interfering users. It is also shown that the near-far resistance of optimum multiuser detection can be achieved by a linear detector. The optimum linear detector for worst-case energies is found, along with existence conditions, which are always satisfied in the models of practical interest. >
916 citations
TL;DR: Under typical operating conditions, a class of suboptimum detectors for data transmitted asynchronously by K users employing direct-sequence spread-spectrum multiple access on the additive white Gaussian noise channel will perform much better than the conventional receiver and often nearly as well as the optimum detector.
Abstract: Consideration is given to a class of suboptimum detectors for data transmitted asynchronously by K users employing direct-sequence spread-spectrum multiple access (DS/SSMA) on the additive white Gaussian noise (AWGN) channel. The general structure of these detectors consists of a bank of matched filters, a linear transformation that operates on the matched-filter outputs, and a set of threshold devices. The linear transformations are chosen to minimize either a mean-squared-error or a weighted-squared-error performance criterion. Each detector can be implemented using a tapped delay line. The number of computations performed per detected bit is linear in K in each case, and the resulting detectors are thus much simpler than the optimum detector. Under typical operating conditions, these detectors will perform much better than the conventional receiver and often nearly as well as the optimum detector. >
852 citations
TL;DR: The temporal and statistical behavior of pseudonoise bursts generated by spectral phase coding of ultrashort optical pulses is discussed and the possibility of ultrahigh speed code-division multiple-access (CDMA) communications using this technique is suggested.
Abstract: A new technique for encoding and decoding of coherent ultrashort light pulses is analyzed. In particular, the temporal and statistical behavior of pseudonoise bursts generated by spectral phase coding of ultrashort optical pulses is discussed. the analysis is motivated by recent experiments that demonstrate high-resolution spectral phase coding of picosecond and femtosecond pulses and suggest the possibility of ultrahigh speed code-division multiple-access (CDMA) communications using this technique. The evolution of coherent ultrashort pulses into low intensity pseudonoise bursts as a function of the degree of phase coding is traced. The results are utilized to analyze the performance of a proposed CDMA optical communications system based upon encoding and decoding of ultrashort light pulses. The bit error rate (BER) is derived as a function of data rate, number of users, and receiver threshold, and the performance characteristics are discussed for a variety of system parameters. It is found that performance improves greatly with increasing code length. >
495 citations
TL;DR: In this article, the authors derived the bit-error probability for a lightwave communications system using an amplitude-shift-keying (ASK) pulse modulation format and employing optical amplifiers such that amplified spontaneous emission noise dominates all other noise sources.
Abstract: A description is given of a relatively simple derivation of the bit-error probability for a lightwave communications system using an amplitude-shift-keying (ASK) pulse modulation format and employing optical amplifiers such that amplified spontaneous emission noise dominates all other noise sources Mathematically, this noise is represented as a Fourier series expansion with Fourier coefficients that are assumed to be independent Gaussian random variables The bit-error probability is given in a closed analytical form that is derived by the approximate evaluation of several integrals appearing in the analysis The author uses the theory to derive the Gaussian approximation and finds that it overestimates the bit-error rate by one to two orders of magnitude >
359 citations
TL;DR: An adaptive array antenna system is proposed that includes a cancellor of cochannel interference that can improve performance by a combination of temporal and spatial filtering, which can achieve stable acquisition and low error rate of demodulated data even in a heavy-interference channel where a conventional array antennas cannot achieve satisfactory acquisition.
Abstract: In the realization of code-division multiple access based on a spread-spectrum communication system, i.e. spread-spectrum multiple access (SSMA), reduction of cochannel interference is an important problem. An adaptive array antenna system is proposed that includes a cancellor of cochannel interference, which can improve performance by a combination of temporal and spatial filtering. While the adaptive array suppresses interference sources with arrival angles different from those of the desired user, the adaptive digital filter-canceller rejects those whose arrival angles are the same as those of the desired user. The proposed system can achieve stable acquisition and low error rate of demodulated data even in a heavy-interference channel where a conventional array antenna system cannot achieve satisfactory acquisition. >
302 citations
23 Jul 1990
TL;DR: In this paper, the authors describe ways to improve the bit error rate (BER) of QAM by using various forms of coding on an increased symbol set, and they consider Rayleigh, rather than the less severe Ricean fading channel to get worst case performance estimates of mobile radio communications.
Abstract: Quadrature amplitude modulation (QAM) is a bandwidth efficient transmission method for digital signals. It is expected that the available spectrum for the proposed personal communications network (PCN) will soon be at a premium as the number of subscribers increases, and changing from binary modulation to QAM may significantly ease the problem. The severe amplitude and phase changes introduced by the fading channels, however, make low error transmission of QAM difficult to achieve, unless procedures are introduced at both the transmitter and the receiver to combat the fading. The authors describe ways to improve the bit error rate (BER) of QAM by using various forms of coding on an increased symbol set. This means that the data throughput, symbol rate and transmission power are unaffected, although the transmitter and receiver are made considerably more complex. They consider Rayleigh, rather than the less severe Ricean fading channel to get worst case performance estimates of mobile radio communications.<
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183 citations
TL;DR: The concepts and the use of novel analytical expressions combining a log-normal model of rain fade with a Moulsley-Vilar distribution for scintillations are illustrated and applied to a very-small-aperture terminal (VSAT) example of a 29/19-GHz digital communications link through the Olympus satellite using M-ary phase shift keying (PSK) modulation schemes.
Abstract: By considering the global fading process on the link caused by rain attenuation and amplitude scintillations, particularly at K/sub a/ band, it is possible to derive a long-term statistical model of the satellite channel capacity. The four-parameter distribution, which combines amplitude scintillations and rain fade within an up/down link system, is presented. Also presented are the degradation (and improvement) of bit error rate (BER) in the presence of amplitude scintillations, thus complementing the flat fade effect due to rain only. By implementation of adaptive communication systems, a more efficient channel capacity utilization is possible. The concepts and the use of novel analytical expressions combining a log-normal model of rain fade with a Moulsley-Vilar distribution for scintillations are illustrated. These are then applied to a very-small-aperture terminal (VSAT) example of a 29/19-GHz digital communications link through the Olympus satellite using M-ary phase shift keying (PSK) modulation schemes. >
145 citations
01 Aug 1990
TL;DR: Results indicate that the perceptron based decision feedbackequaliser provides better bit error rate performance relative to the least mean square decision feedback equaliser, especially in high noise conditions, and biterror rate performance degrades less owing to decision errors and is also less sensitive to gain variation.
Abstract: The paper describes a new approach for a decision feedback equaliser using the multilayer perceptron structure for equalisation in digital communications systems. Results indicate that the perceptron based decision feedback equaliser provides better bit error rate performance relative to the least mean square decision feedback equaliser, especially in high noise conditions, also that bit error rate performance degrades less owing to decision errors and is also less sensitive to gain variation.
130 citations
TL;DR: Computer simulation is used to evaluate the performance of a sequential decoder that uses this metric in conjunction with the stack algorithm, and results are achieved comparable to those obtained using the much more complicated optimal receiver.
Abstract: The application of sequential decoding to the detection of data transmitted over the additive white Gaussian noise channel by K asynchronous transmitters using direct-sequence spread-spectrum multiple access (DS/SSMA) is considered. A modification of R.M. Fano's (1963) sequential-decoding metric, allowing the messages from a given user to be safely decoded if its E/sub b//N/sub 0/ exceeds -1.6 dB, is presented. Computer simulation is used to evaluate the performance of a sequential decoder that uses this metric in conjunction with the stack algorithm. In many circumstances, the sequential decoder achieves results comparable to those obtained using the much more complicated optimal receiver. >
16 Apr 1990
TL;DR: In this paper, an adaptive decision feedback equalizer (DFE) for application in the USA digital cellular radio telephone system was proposed. But the performance sensitivity to time delay spread, Doppler shift, and timing jitter was not evaluated.
Abstract: The authors study an adaptive decision feedback equalizer (DFE) for application in the USA digital cellular radio telephone system. A synchronous DFE and a fractionally spaced DFE are adaptive and use a fast recursive least squares algorithm to track rapid channel variations. Simulation results indicating the performance sensitivity to time delay spread, Doppler shift, and timing jitter are presented. A DFE using a complex fast-Kalman adaptation algorithm is presented, and its bit error rate performance evaluated. The fast Kalman equalizer is found to possess good tracking ability and can track channel variations at vehicle speeds of 50 mph (80 km/h). Sensitivity to sample timing jitter can be reduced by using a DFE with fractionally spaced feedforward taps. >
TL;DR: A technique for characterizing multiuser interference and background noise in a direct-sequence spread-spectrum network is introduced, and packet error probabilities are calculated and modifications to the basic direct- sequence scheme that improve performance in the case of one strong interferer are suggested.
Abstract: A technique for characterizing multiuser interference and background noise in a direct-sequence spread-spectrum network is introduced, and packet error probabilities are calculated. The multiuser interference over a packet in the network is modeled as a compound Gaussian multivariate random variable for moderate to large values of the processing gain. The conditional variance is dependent on the number of users and their interference powers. The method works for any interference with statistics of the block interference having a spherically symmetric distribution. The best performance results, in terms of the expected total interference power, are obtained for the case of a large number of interferers with comparable interference powers. As the number of interferers approaches infinity, the performance is the same as that for Gaussian noise. For a small number of interferers, the block error probability curve is broader than that for Gaussian noise. For small values of SNR, the probability of error is smaller than that corresponding to Gaussian noise, and for large values of SNR it is larger. Modifications to the basic direct-sequence scheme that improve performance in the case of one strong interferer are suggested. >
TL;DR: The idea of using a multiple (more than two) symbol observation interval to improve error probability performance is applied to differential detection of trellis-coded multiple phase-shift keying over an additive white Gaussian noise (AWGN) channels.
Abstract: The idea of using a multiple (more than two) symbol observation interval to improve error probability performance is applied to differential detection of trellis-coded multiple phase-shift keying (MPSK) over an additive white Gaussian noise (AWGN) channels. An equivalent Euclidean distance measure per trellis branch is determined for this detection scheme. This is used to define an augmented (larger multiplicity) trellis code whose distance measure is the conventional squared Euclidean distance typical of conventional trellis-coded modulation on the AWGN. Such an augmented multiple trellis code is a convenient mathematical tool for simplifying the analysis. Results are obtained by a combination of analysis and computer simulation. It is shown that only a slight increase (e.g. one symbol) in the length of the observation interval will provide a significant improvement in bit error probability performance. >
02 Dec 1990
TL;DR: Suboptimal, low-complexity nonlinear equalizer structures derived from the probabilistic symbol-by-symbol maximum a posteriori probability (MAP) algorithm and the M-ary soft-output Viterbi algorithm (SOVA) are investigated.
Abstract: Suboptimal, low-complexity nonlinear equalizer structures derived from the probabilistic symbol-by-symbol maximum a posteriori probability (MAP) algorithm and the M-ary soft-output Viterbi algorithm (SOVA) are investigated. Both algorithms deliver reliability information for each symbol. The complexity of both algorithms in their simplest form is of the order of the conventional reduced-state Viterbi equalizer with hard outputs. Simulation results for a terrestrial time-varying frequency-selective fading channel are given. Realistic channel estimation at high Doppler speeds is included. The coding gain of the investigated 8-state trellis-coded 8-PSK scheme is about 6 dB at a BER (bit error rate) of 10/sup -3/. The gain by making use of soft-decisions is about 4-5 dB at a BER of 10/sup -3/. >
TL;DR: The method provides an accurate approximation and a tight upper bound to the bit error probability and allows the effect of unequal power levels on other-user interference in FH/SSMA systems to be quantified accurately for the first time.
Abstract: A method for the evaluation of the probability of error of uncoded asynchronous frequency-hopped spread-spectrum multiple-access communications is presented. For systems with binary FSK modulation this method provides an accurate approximation and a tight upper bound to the bit error probability; for systems with M-ary FSK modulation, it provides tight upper bounds to the symbol error probability. The method enables the computationally efficient averaging of the error probability with respect to the delays, phase angles, and data streams of the different users. It relies on the integration of the product of the characteristic function of the envelope of the branch of the BFSK demodulator, which carries the desired signal, and of the derivative of the characteristic function of the envelope of the other branch. For sufficient frequency separation between the BFSK tones, the method can achieve any desirable accuracy. Moreover, the computational effort required for its evaluation grows linearly with the number of interfering users. In the M-ary case, tight upper bounds based on the union bound and the results of the binary case are derived. The method allows the effect of unequal power levels on other-user interference in FH/SSMA systems to be quantified accurately for the first time. The results indicate that the FH/SSMA systems suffer from the near-far problem, although less seriously than direct-sequence SSMA systems. >
TL;DR: The time-dependent adaptive filters that allow for the cyclostationary nature of communication signals by periodically changing the filter and adaptation parameters are examined and are shown to be more effective than the time-independent adaptive filter for interference rejection.
Abstract: Time-dependent adaptive filters (TDAFs) that allow for the cyclostationary nature of communication signals by periodically changing the filter and adaptation parameters are examined. The TDAF has an advantage over the conventional time-independent adaptive filter in achieving better performance, i.e. reduced mean square error (MSE), for signals with periodic statistics. The basic theory of the TDAF is presented. The TDAF is shown to be more effective than the time-independent adaptive filter for interference rejection. This is verified by theoretical analysis and computer simulation of specific cases of extracting a signal in noise or interference. The criteria for judging the performance of the TDAF for interference rejection are MSE, bit error rate measurements, and constellation diagrams. >
TL;DR: In this article, the authors describe a burstmode receiver for optical data communication that employs a differential transimpedance amplifier and an auto-threshold-tracking level control circuit in the preamplifier.
Abstract: A description is given of the characteristics and performance of a burst-mode receiver for optical data communication that employs a differential transimpedance amplifier and an auto-threshold-tracking level control circuit in the preamplifier. The differential outputs of the preamplifier are DC-coupled to the decision circuit to achieve burst-mode compatibility. The receiver was assembled in a compact dual inline package with an optical connector. The typical sensitivities are around -31.5 and -29.5 dBm/Av at 200 Mb/s (at a bit error rate of 10/sup -9/) for pseudorandom and burst-mode signals, respectively, with dynamic ranges of 27.5 and 25.5 dB, respectively. The operating bit rate ranges from DC to 500 Mb/s, and the differential outputs are true ECL (emitter-coupled logic). >
TL;DR: In this article, it is shown that channel capacity can be improved using squeezed light by only a factor of two. But this is only for very high-efficiency systems, where optical losses and electronic noise reduce the improvement expected to the 10-20% level.
Abstract: Coherent lightwave communications systems are approaching a limit where the error rates and channel capacities are limited by the quantum properties of light. This is often referred to as the shot-noise limit. If ideal laser light is used in the system, there is no way to avoid this limit. However, new states of the light field called squeezed states have recently been developed that allow an improvement in error rates below the shot-noise limit. Squeezed light concepts and recent experiments are reviewed with emphasis on aspects important to coherent communications. It is shown that channel capacity can be improved using squeezed light by only a factor of two. Larger improvements are in principle possible for error rates, e.g. a factor of three reduction in the number of required photons per bit for a 10/sup -9/ bit error rate. An example of a recent high-performance system is described where optical losses and electronic noise reduce the improvement expected using squeezed light to the 10-20% level. It is concluded that squeezed light only offers significant improvement in bit error rates for very-high-efficiency systems. >
Patent•
12 Feb 1990
TL;DR: In this article, bit data is transmitted bit by bit from one of two units, one of which has an M-series generator, and the other has a reception unit that stores the first and second M0 -series signals on the transmission side as reference signals.
Abstract: In response to a bit transfer request from one of two units, bit data is transmitted bit by bit from the other of the two units. The unit on the transmission side for transmitting the bit data has an M-series generator. In response to bit 1, a first M0 -series signal of a 63-word length is generated. In response to bit 0, a second M0 -series signal in which the series start position is set to the intermediate position of the first M0 -series signal, although the signal is the same M0 -series signal of the 63-word length, is generated. The unit on the reception side has previously stored the first and second M0 -series signals on the transmission side as reference signals, and calculates the correlations between the two reference signals and the reception signal, and demodulates the data bit corresponding to the reference signal having a larger correlation value.
TL;DR: The results show that large amounts of signal-to-noise ratio (SNR) are required to compensate for the combined effect of fading and shadowing.
Abstract: An analytical derivation of the probability of bit error noncoherent frequency-shift keying (FSK) and coherent phase-shift keying (PSK) signals transmitted through a land-mobile satellite channel is described. The channel characteristics used in the analysis are based on a recently developed model which includes the combined effects of fading and shadowing. Analytical expressions for the probability of bit error of FSK and coherent phase-shift keying (CPSK) signals are obtained. The results show that large amounts of signal-to-noise ratio (SNR) are required to compensate for the combined effect of fading and shadowing. An analytical expression for the irreducible probability of bit error of a CPSK signal due to phase variations caused by fading and shadowing is derived. The results described should be useful in the design of land mobile satellite communication systems. >
Patent•
13 Feb 1990
TL;DR: In this paper, a digital differential phase-shift keyed demodulator is proposed to demodulate the differential phase shift keyed data, thereby reducing the time needed to acquire the Mode S uplink or interrogation signal.
Abstract: The present invention is directed to a Mode S uplink or interrogation signal demodulation system which can quickly recognize the Mode S signal and also filter out of noise present in the Mode S uplink or interrogation signal, thereby reducing the bit error rate. To realize this goal the present invention includes a digital differential phase-shift keyed demodulator to demodulate the differential phase-shift keyed data, thereby reducing the time needed to acquire the Mode S uplink or interrogation signal. This digital demodulator also reduces the noise present in the Mode S uplink or interrogation signal and provides an integrated system which is small in structure that can be easily implemented in an aircraft. This Mode S system also includes a preamble and sync phase reversal detection circuit to recognize if the transmitted signal is a Mode S signal. This signal also utilizes Mode A and Mode C detection devices to make the system compatible with present communication systems.
Patent•
19 Mar 1990TL;DR: In this article, the framing bit errors of a received digital communications signal are monitored and recorded and an audible alarm is sounded when the error rate exceeds a predetermined threshold value in a plurality of calculation modes.
Abstract: The framing bit errors of a received digital communications signal are monitored and recorded. The framing bit error rate is determined and an audible alarm is sounded when the error rate exceeds a predetermined threshold value in a plurality of calculation modes. The framing bit error rate and the total framing bit errors detected over a predetermined fixed time period is also displayed. A link to a remote network monitor can be implemented for monitoring and displaying framing bit error rate at a remote location.
Patent•
08 Jun 1990TL;DR: In this paper, a memory system provides a method for error detection and correction, where large data words are divided into multiple error correction zones, and one zone from each of two or more words are combined to form an error domain.
Abstract: A memory system provides a method for error detection and correction. Large data words are divided into multiple error correction zones. One zone from each of two or more words are combined to form an error domain. Address bits are also included in the domains. Check bits are generated from the data bits in each domain and stored with the data. During data retrieval, each domain is processed separately, generating a syndrome for each domain. The syndromes provide indication of bit errors, allowing the correction of a single-bit error in each domain. Multiple-bit errors may thus be corrected within each word using a single-bit error correction code. Data are distributed in physical memory so that, within each domain, no more than one data bit is stored in the same memory device. This method provides full error correction capability in the presence of a catastrophic memory package failure, so long as failures in multiple packages do not cause multiple errors within a single error correction domain. During both read and write operations, error correction code processing may be performed in parallel for multiple domains, enhancing performance.
TL;DR: In this paper, a low-overhead method of protecting multi-pulse speech coders from the effects of severe random or fading pattern bit errors combines a standard error correcting code (convolutional rate 1/2 coding and Viterbi trellis decoding) for protection in random errors with cyclic redundancy code (CRC) error detection for fading errors.
Abstract: A low-overhead method of protecting multi-pulse speech coders from the effects of severe random or fading pattern bit errors combines a standard error correcting code (convolutional rate 1/2 coding and Viterbi trellis decoding) for protection in random errors with cyclic redundancy code (CRC) error detection for fading errors. Compensation for detected fading errors takes place within the speech coder. Protection is applied only to the perceptually significant bits in the transmitted frame.
TL;DR: Protection of a digital multi-pulse speech coder from fading pattern bit errors common in a digital mobile radio channel is accomplished with error detection techniques which are simple to implement and require no error correcting codes.
Abstract: Protection of a digital multi-pulse speech coder from fading pattern bit errors common in a digital mobile radio channel is accomplished with error detection techniques which are simple to implement and require no error correcting codes. A synthetic regeneration algorithm is employed which uses only the perceptually significant bits in the transmitted frame. Separate parity checksums for line spectrum pair frequency data, pitch lag data and pulse amplitude data are added to each frame of speech coder bits in the transmitter. The bits are then transmitted through a mobile environment susceptible to fading that induces bursty error patterns in the stream. At the receiving station, the parity checksum bits and speech coder bits are used to determine if an error has occurred in a particular section of the bit stream. Detected errors are flagged and supplied to the speech decoder. The speech decoder uses the error flags to modify its output signal so as to minimize perceptual artifacts in the output speech. Separate checksums are developed for subsets of line spectrum pair (LSP) coefficients and related speech data, whereby a single subset may be error-detected and replaced, rather than an entire frame.
TL;DR: In burst digital transmission using PSK (phase shift keying) modulation with coherent detection, the recovery of the carrier reference phase and the symbol clock is a key aspect and a digital processor for carrier recovery without preambles is considered.
Abstract: In burst digital transmission using PSK (phase shift keying) modulation with coherent detection, the recovery of the carrier reference phase and the symbol clock is a key aspect. If all users have a common clock synchronization, symbol timing needs not to be recovered in each burst. A digital processor for carrier recovery without preambles, in the presence of frequency offset, is considered. As an example, a 2 Mb/s QPSK transmission system is considered in which E/sub b//N/sub o/=10 dB, and the burst and estimation interval length L=15. Using the algorithm described and averaging eight successive estimated frequency offsets, in order to eliminate anomalous errors, the BER (bit error rate) degradation is equal to 0.14 dB when Delta f=20 kHz. >
TL;DR: An analysis is made of the impact of various design decisions on the error detection capability of the fiber distributed data interface (FDDI), a 100-Mb/s fiber-optic LAN standard being developed by the ANSI, and the frame error rate, token loss rate, and undetected error rate are quantified.
Abstract: An analysis is made of the impact of various design decisions on the error detection capability of the fiber distributed data interface (FDDI), a 100-Mb/s fiber-optic LAN standard being developed by the American National Standards Institute (ANSI). In particular, the frame error rate, token loss rate, and undetected error rate are quantified. Several characteristics of the 32-b frame check sequence (FCS) polynomial, which is also used in IEEE 802 LAN protocols, are discussed. The standard uses a nonreturn to zero invert on ones (NRZI) signal encoding and a 4-b to 5-b (4b/5b) symbol encoding in the physical layer. Due to the combination of NRZI and 4b/5b encoding, many noise events are detected by code (or symbol) violations. A large percentage of errors are detected by FCS violations. The errors that escape these three violations remain undetected. The probability of undetected errors due to creation of false starting delimiters, false ending delimiters, or merging of two frames is analyzed. It is shown that every noise event results in two code bit errors, which in turn may result in up to four data bit errors. The FCS can detect up to two noise events. Creation of a false starting delimiter or ending delimiter on a symbol boundary also requires two noise events. This assumes enhanced frame validity criteria. The author justifies the enhancements by quantifying their effect. >
TL;DR: A very simple algorithm to implement an adaptive scheme to improve the throughput of conventional automatic-repeat-request protocols by dynamically adapting the protocol block length so that it approaches the optimum value for varying channel bit error rates.
Abstract: The throughput of conventional automatic-repeat-request (ARQ) protocols, such as the stop-and-wait, go-back-N, and selective repeat, can be improved by dynamically adapting the protocol block length so that it approaches the optimum value for varying channel bit error rates. A very simple algorithm to implement such an adaptive scheme is presented. The algorithm assumes a known block error rate, estimates the bit error rate, and determines the best block length. Results of a simulation study show that in spite of its simplicity, the algorithm performs well. >
TL;DR: The authors derive a canonical representation for discrete nonlinear systems, based on a linear convolutional code and a memoryless mapper, that shows that finite-memory, discrete non linear systems can be analyzed in much the same way as TCM (trellis-coded modulation) schemes.
Abstract: The computation of upper and lower bounds to error probability in digital transmission over nonlinear channels with a finite memory is considered. By using orthogonal Volterra series, the authors derive a canonical representation for discrete nonlinear systems, based on a linear convolutional code and a memoryless mapper. This representation shows that finite-memory, discrete nonlinear systems can be analyzed in much the same way as TCM (trellis-coded modulation) schemes. In particular, TCM over nonlinear channels can be analyzed. A technique is derived that expresses an upper bound to error probability based on the computation of the transfer of a state diagram with N branches, and whose branch labels are matrices rather than scalars. Some examples of its application are given. In particular, error bounds are derived for nonlinear TCM schemes and for TCM schemes operating on nonlinear channels. >