Benoit Chatelain

Peak-to-average power ratio and intersymbol interference reduction by Nyquist pulse optimization

The efficiency of a power amplifier is partly determined by the peak-to-average power ratio (PAPR) of the modulated signal. Communication systems using high order QAM have large PAPR resulting in low efficiency and a high level of intermodulation distortion. In this paper, we propose a simultaneous minimization of the PAPR of the transmitted signal and the intersymbol interference (ISI) of the demodulated signal based on the optimization of the root raised cosine (RRC) filter. This is performed under spectral requirement constraints using a multivariate optimization technique. It is shown that the use of the proposed filters significantly increases the power amplifier efficiency while preserving the symbol error rate (SER) performance; 1.85 dB of power increase is typically obtained. Alternatively, they may be used to lower the spectral emissions and improve the error probability. The results were measured on a radio to obtain a 7 to 11 dB out of band signal power reduction.

SPM-Tolerant Pulse Shaping for 40- and 100-Gb/s Dual-Polarization QPSK Systems

An intersymbol-interference-free pulse shape is specifically designed for self-phase-modulation (SPM) mitigation. It is experimentally shown to increase the SPM tolerance of a 40-Gb/s single-channel postcompensated dual-polarization quadrature phase-shift keying system by 1.5 dB. Numerical analyses at 40 and 100 Gb/s indicate that the specialized pulse shape can increase the maximum reach for G.652 fiber and G.655 fiber up to 1190 and 820 km, respectively.

Decision directed least radius distance algorithm for blind equalization in a dual-polarization 16-QAM system

Robust PMD tolerance and fast pre-convergence speed of decision directed least radius distance algorithm is demonstrated via a 224Gb/s dual-polarization 16-QAM system simulation.

Non-Cooperative Design of Translucent Networks

This paper introduces a new game theoretic formulation for the design and routing of resilient and translucent networks. An integer linear programming (ILP) modeling is also presented and used as a reference to evaluate the game theoretic algorithm performances. Both formulations include primary and link-disjoint protection paths pre-calculation and take into account the system maximal optical reach distance. Numerical results show that the game theoretic formulation considerably decreases the optimization time and provides near optimal solutions, in term of required number of regenerator nodes.

Optimized pulse shaping for intra-channel nonlinearities mitigation in a 10 Gbaud dual-polarization 16-QAM system

An optimized pulse shape is shown to reduce intra-channel nonlinear effects in a 10 Gbaud dual-polarization 16-QAM EDFA-amplified system without optical dispersion compensation.

Topological Wavelength Usage Estimation in Transparent Wide Area Networks

A power law relationship is established between wavelength usage and algebraic connectivity of backbone wavelength division multiplexing networks. From this observation, a concise prediction formula linking wavelength consumption to network topologies is derived and evaluated for real-world wide area networks. It is shown that the algebraic-connectivity-based wavelength usage estimation is more precise than evaluations relying on node degree variance, number of spanning trees, and average internodal distance.

Tabu search optimization in translucent network regenerator allocation

This paper introduces the Tabu Search optimization algorithm to solve the regenerator allocation problem in translucent networks. The problem consists of finding the minimum number of regenerator nodes which primarily affects the cost of the translucent network. The problem is first solved with an ILP formulation to find the optimal solution without taking into consideration its time performance. The optical reach limit due to the dispersion compensation module and full (static) traffic demand with a 1+1 protection scheme are considered in the network model. The proposed algorithm is then compared with two other heuristics: the maximum infeasibility reduction (MIR) algorithm and the maximum regeneration demand (MRD) algorithm. Numerical results show that the Tabu Search procedure either outperforms or equals the performance of the reference algorithms, while having a lower implementation complexity and comparable convergence speed.

A Dual Metaheuristic Solution to the Min-RWA Problem

A new routing and wavelength assignment (RWA) algorithm for all-optical networks is introduced. A genetic algorithm, minimizing the networks link congestion, is combined with tabu search. Optimal solutions are found for nearly all test cases.

Multiplierless Evolutionary Filter Design

Evolutive algorithms have demonstrated their potential as optimizers in a wide variety of applications. Automated evolutionary design of analog filters, antennas, logical gates and micro-electro-mechanical systems (MEMS) has resulted in unexpected but efficient topologies and configurations. In this paper, we present an automated design procedure for digital filters based on the use of a genetic algorithm (GA) and high level primitives such as delays, bit shift operators and adders. Given the performance criteria, the proposed algorithm autonomously decides on the components use and circuit configuration. Compared to traditional infinite impulse response (IIR) and canonical signed digits (CSD)-IIR filters, synthesis results show that the evolutionary designed (ED) filter can attain a twofold increase in speed and requires less hardware resource.

Impact of spectral shaping location on the performance of communication transceivers

In this paper, the impact of the filtering location in a communication transceiver is investigated. In a classic architecture, the spectral shaping is done in base band, i.e., before signal amplification. This approach may increase significantly the peak-to-average of the signal. This in turn means that the power amplifier has to be operated at a higher back-off thus increasing its size and reducing its DC-RF efficiency. The use of analog filtering after amplification can circumvent these limitations. However, given the limited control on the analog filter, system linearity will be affected. In this paper, we study and compare the performance of both architectures with digital and analog filters. It is found that an optimized digital filter at the receiver allows obtaining excellent linearity with analog, post-amplifier, filter at the transmitter.