Papers by Giulio Colavolpe
IEEE Transactions on Communications
Lecture Notes in Computer Science, 2004
In this paper we describe a method, based on a genetic algorithm, for generating good (in terms o... more In this paper we describe a method, based on a genetic algorithm, for generating good (in terms of minimum distance) linear block error-correcting codes. Preliminary experimental results indicate that the method can be very effective, especially in terms of fast generation of good sub-optimal codes.
International Symposium onInformation Theory, 2004. ISIT 2004. Proceedings., 2004
The subject of this paper is the asymptotic optimality of finite-memory detection for transmissio... more The subject of this paper is the asymptotic optimality of finite-memory detection for transmission over a channel characterized by a single multiplicative time-invariant stochastic parameter (e.g., block frequency non-selective fading). It is known that any finite-memory detection algorithm, either trellisbased or graph-based, is characterized by a single basic metric. We present a theorem which proves that this metric tends, asymptotically, to that of a receiver with perfect channel state information.
IFIP International Federation for Information Processing, 2005
In high-speed optical transmission systems, one of the most challenging impairments is represente... more In high-speed optical transmission systems, one of the most challenging impairments is represented by the signal distortions produced by polarization-mode dispersion (PMD). In this paper, we analyze the limits of electronic compensation schemes, in the form of maximum-likelihood sequence detection receivers. With a constraint on the front-end processing after photo-detection, we compute the signal statistics necessary to implement this strategy. The receiver adaptivity is also discussed. The relevant performance is analyzed by means of computer simulations and accurate analytical performance bounds, and compared with the performance of all-optical compensators and decision-feedback equalizers. A significant performance loss with respect to optical compensation is observed for large values of the differential group delay (DGD) showing that, after the non reversible transformation operated by the photo-detector, it is not possible to effectively cope with the PMD-induced impairments.
Seventh International Symposium on Signal Processing and Its Applications, 2003. Proceedings., 2003
In this paper, we propose linear predictive receivers for phaseuncertain channels. These receiver... more In this paper, we propose linear predictive receivers for phaseuncertain channels. These receivers are attractive from a conceptual viewpoint because they generalize previous solutions based on noncoherent sequence detection. On the practical side, the proposed algorithms lend themselves to the implementation of adaptive receivers capable of copying with possible time variations of the statistics of the underlying phase model.
ABSTRACT Conference code: 85176, Export Date: 25 July 2012, Source: Scopus, Language of Original ... more ABSTRACT Conference code: 85176, Export Date: 25 July 2012, Source: Scopus, Language of Original Document: English, Correspondence Address: Razzano, E.; Carlo Gavazzi Space S.p.A., Via Nomentana 60, Roma, Italy; email: erazzano@cgspace.it, References: Scorzolini, A., De Perini, V., Razzano, E., Simionato, P., (2010) Satellite Based AIS for Maritime Safety, , Tolouse Space Show France;
2009 IEEE International Symposium on Information Theory, 2009
... Marco Secondini*, Dario Fertonani*, Giulio Colavolpe**, and Enrico Forestieri* *Scuola Superi... more ... Marco Secondini*, Dario Fertonani*, Giulio Colavolpe**, and Enrico Forestieri* *Scuola Superiore Sant'Anna, Pisa - Italy ... is equal (or proportional) to the conditional pdf p(yla == a) [1], [2]. In the following, only systems that can be described as a finite-state machine (FSM) [2] are ...
GLOBECOM '05. IEEE Global Telecommunications Conference, 2005., 2005
In this paper, we derive low-complexity MAP symbol detection algorithms for continuous phase modu... more In this paper, we derive low-complexity MAP symbol detection algorithms for continuous phase modulations (CPMs). To obtain this result, the well-known problem of a transmission over an additive white Gaussian noise (AWGN) channel affected by known intersymbol interference (ISI) is first considered. We show that the maximum a posteriori (MAP) symbol detection strategy, usually implemented by using the Forney observation
Euromicro Symposium on Digital System Design, 2004. DSD 2004., 2004
This paper presents a 2048 bit, rate 1/2 soft decision decoder for a new class of codes known as ... more This paper presents a 2048 bit, rate 1/2 soft decision decoder for a new class of codes known as turbo Gallager codes. The decoder can support up to 1 Gbit/s code rate and performs up to 48 decoding iteration ensuring at the same time high throughput and good coding gain. In order to evaluate the performance and the gate complexity
IEEE Communications Letters, 2015
We consider soft-output detection of a binary continuous phase modulation (CPM) generated through... more We consider soft-output detection of a binary continuous phase modulation (CPM) generated through a low-cost transmitter, thus characterized by a significant modulation index uncertainty, and sent over a channel affected by phase noise. The proposed detector is designed by adopting a simplified representation of a binary CPM signal with the principal component of its Laurent decomposition and is obtained by using the framework based on factor graphs and the sum-product algorithm. It does not require an explicit estimation of the modulation index nor of the channel phase and is very robust to large uncertainties of the nominal value of the modulation index. Being soft-output in nature, this detector can be employed for iterative detection/decoding of practical coded schemes based on a serial concatenation, possibly through a pseudo-random interleaver, of an outer encoder and a CPM modulation format.
2010 5th Advanced Satellite Multimedia Systems Conference and the 11th Signal Processing for Space Communications Workshop, 2010
A recent study of an European consortium (TPZ, Carlo Gavazzi Space, Edisoft, Elman, ITS) led by T... more A recent study of an European consortium (TPZ, Carlo Gavazzi Space, Edisoft, Elman, ITS) led by Telespazio and co-financed by ESA has investigated about the possibility of receiving AIS signals (i.e., AIS transmissions of vessels equipped with regular AIS transponders) from space with an improved performance with respect to the current literature thanks to an optimized mission design and enhanced technical capabilities mainly in terms of antennas and signal processing.The performances is assessed by means of a dedicated end-to-end System Simulator developed during the project.
International Journal of Satellite Communications and Networking, 2014
ABSTRACT In this tutorial paper, we first review the main information–theoretic results on channe... more ABSTRACT In this tutorial paper, we first review the main information–theoretic results on channels affected by a time-varying phase noise. The main maximum a posteriori symbol detection algorithms to be employed in such a challenging scenario are then described considering linear modulations and advanced coding schemes based on iterative detection and decoding. The role of pilot symbols will be also discussed. Copyright © 2013 John Wiley & Sons, Ltd.
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 2006
The most powerful channel coding schemes, namely those based on turbo codes and low-density parit... more The most powerful channel coding schemes, namely those based on turbo codes and low-density parity-check (LDPC) Gallager codes, have in common the principle of iterative decoding. However, the relative coding structures and decoding algorithms are substantially different. This paper presents a 2048-bit, rate-1/2 soft decision decoder for a new class of codes known as Turbo Gallager Codes. These codes are turbo codes with properly chosen component convolutional codes such that they can be successfully decoded by means of the decoding algorithm used for LDPC codes, i.e., the belief propagation algorithm working on the code Tanner graph. These coding schemes are important in practical terms for two reasons: (i) they can be encoded as classical turbo codes, giving a solution to the encoding problem of LDPC codes; (ii) they can also be decoded in a fully parallel manner, partially overcoming the routing congestion bottleneck of parallel decoder VLSI implementations thanks to the locality of the interconnections. The implemented decoder can support up to 1 Gbit/s data rate and performs up to 48 decoding iterations ensuring both high throughput and good coding gain. In order to evaluate the performance and the gate complexity of the decoder VLSI architecture, it has been synthesized in a 0.18 µm standard-cell CMOS technology.
IEEE Transactions on Wireless Communications, 2000
... (10) depend on αn and φn−1 only. In order to implement the MAP sequence detection strategy, t... more ... (10) depend on αn and φn−1 only. In order to implement the MAP sequence detection strategy, the maximization of the pdf p(r|α) can be performed by using the Viterbi al-gorithm with branchmetrics given by ln Gn ... We now derive the MAP symbol detection strategy for this case. ...
IEEE Transactions on Wireless Communications, 2000
The problem of detection and decoding of lowdensity parity-check (LDPC) codes transmitted over ch... more The problem of detection and decoding of lowdensity parity-check (LDPC) codes transmitted over channels with memory is addressed. A new general method to build a factor graph which takes into account both the code constraints and the channel behavior is proposed and the a posteriori probabilities of the information symbols, necessary to implement maximum a posteriori (MAP) symbol detection, are derived by using the sum-product algorithm. With respect to the case of a LDPC code transmitted on a memoryless channel, the derived factor graphs have additional factor nodes taking into account the channel behavior and not the code constraints. It is shown that the function associated to the generic factor node modeling the channel is related to the basic branch metric used in the Viterbi algorithm when MAP sequence detection is applied or in the BCJR algorithm implementing MAP symbol detection. This fact suggests that all the previously proposed solutions for those algorithms can be systematically extended to LDPC codes and graph-based detection.
IEEE Transactions on Communications, 2000
The most powerful channel-coding schemes, namely, those based on turbo codes and low-density pari... more The most powerful channel-coding schemes, namely, those based on turbo codes and low-density parity-check (LDPC) Gallager codes, have in common the principle of iterative decoding. However, the relative coding structures and decoding algorithms are substantially different. This paper shows that recently proposed novel coding structures bridge the gap between these two schemes. In fact, with properly chosen component convolutional codes, a turbo code can be successfully decoded by means of the decoding algorithm used for LDPC codes, i.e., the belief-propagation algorithm working on the code Tanner graph. These new turbo codes are here nicknamed "turbo Gallager codes." Besides being interesting from a conceptual viewpoint, these schemes are important on the practical side because they can be decoded in a fully parallel manner. In addition to the encoding complexity advantage of turbo codes, the low decoding complexity allows the design of very efficient channel-coding schemes.
IEEE Transactions on Communications, 2005
In this paper, based on the application of the sum-product (SP) algorithm to factor graphs (FGs) ... more In this paper, based on the application of the sum-product (SP) algorithm to factor graphs (FGs) representing the joint a posteriori probability (APP) of the transmitted symbols, we propose new iterative soft-input soft-output (SISO) detection schemes for intersymbol interference (ISI) channels. We have verified by computer simulations that the SP algorithm converges to a good approximation of the exact marginal APPs of the transmitted symbols if the FG has girth at least 6. For ISI channels whose corresponding FG has girth 4, the application of a stretching technique allows us to obtain an equivalent girth-6 graph.
IEEE Photonics Technology Letters, 2000
Maximum likelihood sequence detection represents the most efficient technique in the electrical d... more Maximum likelihood sequence detection represents the most efficient technique in the electrical domain to combat fiber impairments such as polarization-mode dispersion and group-velocity dispersion. In order to successfully apply this technique, it is mandatory to estimate some key channel parameters needed by the Viterbi processor. We propose a simple and effective solution based on the least-mean-square algorithm to perform such an estimation.
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Papers by Giulio Colavolpe