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We propose a subspace-based maximum-likelihood approach for acquiring the timing of wavelet-based multirate transmission systems. The S-curve analysis shows that our approach can correctly acquire the initial timing of a symbol from anywhere within a symbol-time interval at a cost of increasing jitter variance.

In a recent paper, the modified Gardner detector has been proposed for advanced symbol-timing recovery of M-ary phase-shift keying signals. Compared with the original algorithm, the self-noise jitter can be considerably reduced for highly bandlimited systems and smaller values of M. In this letter, a completely different approach is investigated, which improves the self-noise performance for larger values of M, as well

In this paper, we present for the first time an analytical model that quantifies the mechanism by which offset size affects priority in multiclass optical-burst switching (OBS) systems. Using the model, we derive an exact expression for the distribution of the number of bursts that contend with an arriving burst. The model is applicable to systems in which each class has an arbitrary burst-length distribution and an arbitrary offset size. We also derive accurate approximate expressions for the burst-blocking probability of premium-class traffic, as well as expressions for the sensitivity of premium-class performance to offset jitter and variations in the arrival rates of each class. In a case study, we find that scaling up a system in terms of the number of wavelengths and the traffic load significantly improves not only the burst-blocking performance of the premium class, but also its sensitivity to lower class traffic variations. We also use the model to dimension and provision the system to guarantee a minimum level of premium-class blocking and premium-class robustness to low-class load variations.

The mainlobe energy of a member from the class of symbol waveforms with null derivatives at zero crossings is maximized. Thus, a bandlimited pulse shape without intersymbol interference, robust against jitter and timing errors, is obtained. Comparisons to known pulses show advantages for these signals at the expense of bandwidth, which linearly increases with the number of null derivatives. >

The effect of the signal transition variation, due to the signal transition density, data asymmetry, and sinusoidal modulation, on the performance of the data transition tracking loop (DTTL) symbol synchronizer is addressed. These factors will affect the DTTL performance, such as the clock jitter and the cycle slippage rate, and unnecessary system loss may result if the system parameters are not well selected. Given the background of C. S. Tsang and W. C. Lindsey (1986), this result can serve as an engineering design guideline for the DTTL in the context of the signal transition variation. >

A circulating-loop experimental technique to simulate the jitter accumulation of a chain of fiber-optic regenerators is described. This technique allows system designer to establish the jitter accumulation characteristics of systems without the need for many test regenerators. An analytic description of how well the loop technique simulates a china of identical fiber-optic regenerators is presented along with a comparison of calculated and simulated jitter accumulation. >

In this paper, we will analyze the effect accumulated jitter has on the decision making process inside the N th fiber optic regenerator of a long chain of fiber optic regenerators. The criteria for a correct bit decision in the presence of receiver noise, static phase offset, and accumulated input jitter will be derived, and calculations of the bit error rate penalties caused by the presence of known distributions of accumulated input jitter will be made. We will then define the jitter tolerance of a fiber optic regenerator as an effective measure of the regenerator's capability to tolerate incoming accumulated jitter. We will show that excessive bit error rate penalties will not occur if the accumulated input jitter does not exceed the regenerator's measured jitter tolerance template. Finally, the jitter tolerance measurement technique will be used to find the optimum sampling time inside a fiber optic regenerator resulting in a regenerator that is optimized for use in long-haul systems.

It is important to accurately evaluate and reduce jitter accumulation in long-haul digital repeatered lines. Jitter accumulation caused by random pattern signals has already been analyzed. However, periodic pattern signals such as pseudorandom signals are usually used to measure jitter accumulation. This paper describes the difference between the jitter accumulation for both signals and the necessary conditions to accurately estimate jitter accumulation for random pattern signals by using periodic pattern signals. First, it is shown theoretically that systematic jitter for periodic signals saturates, showing a ripple pattern. The limit of increase is determined by the ratio of tank bandwidth and pattern repetition frequency. Up to a certain number of regenerators determined by the ratio, systematic jitter increases in rough proportion to the \sqrt{N} slope. It is also shown that the equation to estimate random pattern jitter accumulation is determined by the measured value for periodic pattern signals. Second, jitter characteristics are simulated by optical signal circulating experiments. The results are in agreement with the analysis. In addition, the reduction effects on periodic signal jitter accumulation caused by timing signal delay and nonlinearity of the limiter in the timing circuit are shown.

The performance of an adaptive echo canceller at the looptimed subscriber end of a digital subscriber loop has been shown to be sensitive to jitter arising from the timing recovery subsystem. We evaluate this degradation for the common timing recovery subsystem consisting of a prefilter, a squarer, and a second-order phase-locked loop. The evaluation shows the influence of equalization, prefilter shape, and phaselocked loop parameters. A narrow-band accurately tuned prefilter, line equalizer, and a narrow-band phase-locked loop are found to be necessary for adequate performance in a 144 kbit/s bipolar-coded digital subscriber loop system employing echo cancellation.

A technique for optimizing the performance of directdetection optical communication receivers for binary signaling in the presence of signal dependent noise, additive noise, and intersymbol interference by minimizing a Chernoff bound on the average error probability is extended to accommodate timing jitter. Receivers are identified which provide significantly improved performance compared to conventional designs, and the performance of a jitter-optimized receiver is shown to be relatively insensitive to variations in the jitter level.