ISI-free Pulses Research Articles

A Novel Two-Parametric ISI-Free Pulse Based on Inverse Hyperbolic Functions

In this letter, a new two-parametric pulse that outperforms state-of-the-art pulses with the best performance in terms of BER is proposed, which is studied in terms of frequency and time domain characteristics. Specifically, the pulse is based on the inverse-hyperbolic functions acsch and asech which are used for the first time for an ISI-free pulse, and its design depends only on the roll-off factor and the timing jitter parameter (i.e., two-parametric design). Finally, the proposed pulse is shown to outperform most of the well-known pulses reported in the literature, since it presents lower error probability, smaller maximum distortion and wider eye-diagram.

ISI-free pulse with piecewise exponential frequency characteristic

A new parametric family of Nyquist ISI-free pulses denoted as Piecewise Flipped-Exponential (PFE) is proposed and investigated in terms of error probability when affected by symbol timing jitter. The proposed pulses use only two design parameters and ensure superior or equal performance compared to the previously reported pulses. The filter design is facilitated by the fact that the optimal value of one parameter is constant for a specified value of excess bandwidth, while the other one shows a cubic relationship with timing offset. We prove the feasibility of the new PFE pulses and illustrate its performance in term of ISI error probability, highlighting key trade-offs. In addition, we discuss and compare the practical implementation details of generating truncated/causal realizations of the filter including its square root response. The PFE pulses are compared with Harris–Moerder pulses that were designed in order to show zero spectral re-growth. The PFE pulses are superior to Harris–Moerder pulses in terms of error probability if timing jitter is present but are outperformed in terms of spectral re-growth.

Construction of new ISI-free pulses using a linear combination of two polynomial pulses

This paper deals with the design of inter-smybol interference free pulses having reduced sensitivity to time synchronization errors. A new improved Nyquist filter is proposed and investigated. Its impulse response is obtained from a linear combination of new Nyquist pulses with different asymptotical decay rates. Error probability results show that the proposed filter outperforms other existing filters. The proposed scenarios aimed at demonstrating the feasibility of the concept.

Two improved nyquist filters with piece-wise rectangular-polynomial frequency characteristics

In this article a novel method for constructing a family of improved Nyquist filters is provided, as well as some guidelines on how the inter-symbol interference (ISI) problem can be approached. The proposed solution for the design of Nyquist pulses is based on a piece-wise rectangular-polynomial frequency characteristic using second and third degree polynomials. The characteristic property of the novel family of ISI-free pulses generated by the proposed filters is the asymptotic decay rate of t−2. By introducing this approach, comparable or better results are obtained in terms ISI performance as compared to several recently proposed pulses.

Improved Nyquist Filters with Piece-Wise Parabolic Frequency Characteristics

This paper presents and investigates a novel approach for constructing a family of ISI-free pulses having an asymptotic decay rate of t <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , and comparable or better ISI performance as compared to several recently proposed pulses. The proposed solution for the design of Nyquist pulses is based on a piece-wise parabolic frequency characteristic. This can be considered as a piece-wise polynomial frequency characteristic with second degree polynomials. It is shown that a lower bit error rate (BER) can be achieved for same values of the roll-off factor, timing jitter, signal to noise ratio and number of interfering pulses, as compared to recently reported pulses.

ISI-free pulses produced by improved Nyquist filter with piece-wise linear characteristic

A family of improved Nyquist filters with a piece-wise rectangular frequency characteristic composed of six nonzero linear segments with variable-length projections onto the frequency axis is investigated. They produce a family of inter-symbol interference-free (ISI-free) pulses with an asymptotic decay rate of t−2 that shows comparable or better inter-symbol interference performance, compared with some recently proposed pulses. The co-ordinates of the points that delimit the linear segments are varied in a limited interval in order to obtain a minimum value of the probability of error when the impulse response is sampled with a small time offset. The results outperform previously reported pulses taken as a reference.

Improved Nyquist filter characteristics using spline interpolation

This paper presents and investigates a novel approach for constructing a family of intersymbol interference (ISI)-free pulses that shows comparable or better ISI performance in the presence of sampling errors, compared with some recently proposed pulses. We propose and discuss a new parametric method for the design of Nyquist filter characteristics using constraints in frequency characteristics construction. The method for constructing the filter characteristics uses a piecewise polynomial approximation of an ideal optimized staircase characteristic by spline functions. The spline polynomials are used to approximate a function that must pass through specified points. The performances of new ISI-free pulses are studied with respect to the ISI error probability. This family provides flexibility in designing an appropriate pulse even after the roll-off factor has been chosen. The results for error probability outperform the fourth-degree polynomial pulse [4].

Improved Nyquist Filters with a Transfer Characteristic Derived from a Staircase Characteristic Interpolated with Sine Functions

This paper investigates a novel approach forconstructing a family of ISI-free pulses produced by improvedNyquist filters with a transfer characteristic derived from anideal stairca ...

ISI-free pulses for high-data-rate ultra-wideband wireless systems

Modified intersymbol interference (ISI)-free pulses and ISI-free band-limited polynomial pulses for ultra-wideband (UWB) communication systems are proposed to provide the possibility of very high data rates not achievable by conventional pulses and the pulse design algorithms available in the literature. The power spectrum of the proposed pulses fits the Federal Communications Commission (FCC) spectral mask for very high data rates that have quantized values with various levels. Using this scheme and a particular choice of design variables, it is possible to design orthogonal pulses that could be used for multi-user data communication after they are truncated for the same time interval. Several possible improvements for these proposed pulses are considered for certain practical cases.

A family of ISI-free polynomial pulses

A family of ISI-free polynomial pulses

ISI-free pulses with reduced sensitivity to timing errors

We consider the linear combination of two ISI free pulses, the raised cosine (RC) and the recently proposed better than raised cosine (BTRC). We determine their optimum combination using the distribution of timing error. The obtained pulses perform better than RC and BTRC for fixed as well as randomly distributed timing errors.

Parametric Construction of Nyquist-I Pulses

A novel parametric approach for constructing families of intersymbol-interference (ISI)-free pulses is presented and examined. Some new pulses so constructed have smaller maximum distortion, a more open receiver eye, and a smaller probability of error in the presence of symbol-timing error than the Nyquist raised-cosine pulse for the same excess bandwidth. The parametric approach gives more degrees of freedom in the design of ISI-free pulses, and subsumes previous ISI-free pulses as special cases. A number of theorems that relate time-domain behaviors of a pulse to the pulse's frequency spectrum are proved. A previously known result relating pulse tail-time decay to discontinuity of the pulse-frequency spectrum is corrected and clarified.

A "better than" Nyquist pulse

A novel ISI-free pulse is presented that has smaller maximum distortion, a more open receiver eye, and a smaller probability of error in the presence of symbol timing error than the Nyquist pulse for the same excess bandwidth.