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Journal ArticleDOI

The effect of interpolation on the BER performance of narrowband BPSK and (O)QPSK on Rician-fading channels

01 Nov 1994-IEEE Transactions on Communications (IEEE)-Vol. 42, Iss: 11, pp 2929-2933
TL;DR: By means of theoretical analysis, it is demonstrated that even simple interpolators, operating at only a few samples per symbol, yield BER degradations that are limited to a small fraction of a dB.
Abstract: This paper deals with the bit error rate (BER) performance of a fully digitally implemented receiver performing coherent detection on a narrowband BPSK or (O)QPSK signal, transmitted over a slow non-frequency selective Rician fading channel. The considered digital receiver operates on samples of the received signal, taken by a fixed clock which is not synchronized to the transmitter clock. Signal samples needed for detection of the information sequence are obtained from interpolation between the available samples. In the case of nonideal interpolation a BER degradation occurs. By means of theoretical analysis, we demonstrate that even simple interpolators, operating at only a few samples per symbol, yield BER degradations that are limited to a small fraction of a dB. This paper is an extension of the work of Erup, Gardner and Harris (see ibid., vol.41, no.6, p.998-1008, 1993) where only the AWGN channel was considered and results were obtained by computer simulations. >
Citations
More filters
Journal ArticleDOI
TL;DR: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered and the degradation of the bit error rate is evaluated.
Abstract: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered. The degradation of the bit error rate (BER), caused by the presence of carrier frequency offset and carrier phase noise is analytically evaluated. It is shown that for a given BER degradation, the values of the frequency offset and the linewidth of the carrier generator that are allowed for OFDM are orders of magnitude smaller than for single carrier systems carrying the same bit rate. >

1,816 citations

Journal ArticleDOI
TL;DR: This work presents a comprehensive review of FIR and allpass filter design techniques for bandlimited approximation of a fractional digital delay, focusing on simple and efficient methods that are well suited for fast coefficient update or continuous control of the delay value.
Abstract: A fractional delay filter is a device for bandlimited interpolation between samples. It finds applications in numerous fields of signal processing, including communications, array processing, speech processing, and music technology. We present a comprehensive review of FIR and allpass filter design techniques for bandlimited approximation of a fractional digital delay. Emphasis is on simple and efficient methods that are well suited for fast coefficient update or continuous control of the delay value. Various new approaches are proposed and several examples are provided to illustrate the performance of the methods. We also discuss the implementation complexity of the algorithms. We focus on four applications where fractional delay filters are needed: synchronization of digital modems, incommensurate sampling rate conversion, high-resolution pitch prediction, and sound synthesis of musical instruments.

1,014 citations

Patent
30 Apr 2001
TL;DR: In this article, a high-speed serial data transceiver includes multiple receivers and transmitters for receiving and transmitting multiple analog, serial data signals at multi-gigabit-per-second data rates.
Abstract: A high-speed serial data transceiver includes multiple receivers and transmitters for receiving and transmitting multiple analog, serial data signals at multi-gigabit-per-second data rates. Each receiver includes a timing recovery system for tracking a phase and a frequency of the serial data signal associated with the receiver. The timing recovery system includes a phase interpolator responsive to phase control signals and a set of reference signals having different predetermined phases. The phase interpolator derives a sampling signal, having an interpolated phase, to sample the serial data signal. The timing recovery system in each receiver independently phase-aligns and frequency synchronizes the sampling signal to the serial data signal associated with the receiver. A receiver can include multiple paths for sampling a received, serial data signal in accordance with multiple time-staggered sampling signals, each having an interpolated phase.

68 citations

Patent
17 Sep 1996
TL;DR: In this paper, a digital communication receiver (10) takes one complex sample (20) of a baseband analog signal (12) per symbol, and a rectangular-to-polar converter (26) separates phase attributes of the complex samples from magnitude attributes.
Abstract: A digital communication receiver (10) takes one complex sample (20) of a baseband analog signal (12) per symbol. A rectangular-to-polar converter (26) separates phase attributes of the complex samples from magnitude attributes. A phase processor (28) identifies clock adjustment opportunities which occur when relatively large phase changes take place between consecutive symbols. A magnitude processor (32) influences symbol timing only during clock adjustment opportunities. The magnitude processor (32) advances symbol timing in a phase locked loop when decreasing magnitude changes are detected during clock adjustment opportunities and retards symbol timing when increasing magnitude changes are detected during clock adjustment opportunities. An interpolator (66) may be used to estimate magnitude values between samples so that magnitude change is determined between sampled magnitude values and estimated magnitude values.

33 citations

Patent
30 Apr 2001
TL;DR: In this paper, the authors proposed an adaptive control logic for analog and/or digital components to minimize the distortion of the analog data signal at the receive end by adapting the equalization parameters to a signal path associated with the analog signal.
Abstract: Methods and systems for minimizing distortions in an analog data signal include equalizing the analog data signal at a receive end. In an embodiment, the invention adapts equalization parameters to a signal path associated with the analog data signal. Adaptive control logic is implemented with analog and/or digital components. In an embodiment, the invention equalizes a discreet-time analog representation of an analog data signal. In an embodiment, the invention digitally controls equalization parameters. In an embodiment, a resultant equalized analog data signal is digitized. In an example implementation, an analog data signal is sampled, a quality of the samples is measured, and one or more equalization parameters are adjusted with digital controls as needed to minimize distortion of the samples. The equalized samples are then digitized. The present invention is suitable for lower rate analog data signals and multi-gigabit data rate analog signals.

28 citations

References
More filters
Book
01 Jan 1983

25,017 citations

Journal ArticleDOI
TL;DR: The author describes the fundamental equation for interpolation, proposes a method for control, and outlines the signal-processing characteristics appropriate to an interpolator.
Abstract: Timing adjustment in a digital modem must be performed by interpolation if sampling is not synchronized to the data symbols. The author describes the fundamental equation for interpolation, proposes a method for control, and outlines the signal-processing characteristics appropriate to an interpolator. A review of previous results and a tutorial exposition of the subject are given, along with new results. >

706 citations

Journal ArticleDOI
TL;DR: The NCO-based control method presented in Part I is shown to be equivalent to a conventional phase locked loop and its operation is verified by simulation, demonstrating that simple interpolators give excellent performance.
Abstract: For pt.I, see ibid., vol.41, no.3, p.502-208 (1993). Properties of a specific class of interpolators that are based upon polynomials are discussed. Several implementations are described, one of which is particularly convenient in practical hardware. Simulations demonstrate that simple interpolators give excellent performance. In many cases, two-point, linear interpolation is adequate. If better performance is needed, classical four-point, third-order polynomials could be used. Better yet, a novel four-point interpolating filter with piecewise-parabolic impulse response can have performance superior to that of the standard cubic interpolator and still be implemented much more simply. The NCO-based control method presented in Part I is shown to be equivalent to a conventional phase locked loop and its operation is verified by simulation. >

640 citations

Journal ArticleDOI
TL;DR: The definition of a new distance measure of optimization of trellis codes transmitted over Rician fading channels, guided by maximizing d/sub free, is proposed.
Abstract: It has been well established that the appropriate criterion for optimum trellis-coded modulation design on the additive white Gaussian noise channel is maximization of the free Euclidean distance. It is shown that when the trellis-coded modulation is used on a Rician fading channel with interleaving/deinterleaving, the design of the code of optimum performance is guided by other factors, in particular, the length of the shortest error-event path, and the product of branch distances (possibly normalized by the Euclidean distance of the path) along the path. Although maximum free distance (d/sub free/) is still an important consideration, it plays a less significant role the more severe the fading is on the channel. These considerations lead to the definition of a new distance measure of optimization of trellis codes transmitted over Rician fading channels. If no interleaving/deinterleaving is used, then once again the design of the trellis code is guided by maximizing d/sub free/. >

613 citations

Journal ArticleDOI
TL;DR: A digital algorithm is proposed that can be implemented very efficiently even at high data rates and allows free-running sampling oscillators and a novel planar filtering method that prevents synchronization hangups.
Abstract: The digital realization of timing recovery circuits for digital data transmission is considered. A digital algorithm is proposed that can be implemented very efficiently even at high data rates. The resulting timing jitter has been computed and verified by simulations. In contrast to other known algorithms, the one presented here allows free-running sampling oscillators and a novel planar filtering method that prevents synchronization hangups. >

604 citations