Showing papers by "Giuseppe Caire published in 1995"
TL;DR: The main building block for the construction of a geometrically uniform coded modulation scheme is a subgroup of G/sup I/, where G is a group generating a low-dimensional signal constellation and I is an index set, and this paper study the properties of these subgroups when G is cyclic.
Abstract: The main building block for the construction of a geometrically uniform coded modulation scheme is a subgroup of G/sup I/, where G is a group generating a low-dimensional signal constellation and I is an index set. In this paper we study the properties of these subgroups when G is cyclic. We exploit the fact that any cyclic group of q elements is isomorphic to the additive group of Z/sub q/ (the ring of integers modulo q) so that we can make use of concepts related to linearity. Our attention is focused mainly on indecomposable cyclic groups (i.e., of prime power order), since they are the elementary "building blocks" of any abelian group. In analogy with the usual construction of linear codes over fields, we define a generator matrix and a parity check matrix. Trellis construction and bounds on the minimum Euclidean distance are also investigated. Some examples of coded modulation schemes based on this theory are also exhibited, and their performance evaluated. >
44 citations
TL;DR: In this paper, the authors considered the iterated product of binary single-parity-check codes and showed that their weight distribution asymptotically approaches that of random coding if the smallest code length in the product approaches infinity.
Abstract: We consider the iterated product of binary single-parity-check (spc) codes. We show that their weight distribution asymptotically approaches that of random coding if the smallest code length in the product approaches infinity. According to a specific criterion, the best choice of the product parameters consists of taking all spc codes of equal length. Estimates of the weight distribution obtained by simulation show that even moderately long codes have a weight distribution close to that obtained in the average by random coding. We also discuss decoding of these codes by iterated replication decoding and report results of its simulation.
29 citations
17 Sep 1995
TL;DR: This work states the iterated decoding algorithm formally and provides a conjecture on the convergence and the asymptotic optimality of this algorithm.
Abstract: The concept of iterated decoding of concatenated codes has been developed. Successful applications of this concept include turbo-codes and soft-decoding of product codes. After stating the iterated decoding algorithm formally, we provide a conjecture on the convergence and the asymptotic optimality of this algorithm.
6 citations
14 Nov 1995
TL;DR: The results show the effectiveness of diversity as a way to combat the irreducible error floor due to co-channel interference in fading channels.
Abstract: We study the impact of diversity on coded digital communication systems operating over channels affected by co-channel interference and by independent flat Rayleigh fading. We provide bounds on error probability, an error floor analysis, simulation results, and an asymptotic analysis of the diversity channel as the diversity order increases. Our results show the effectiveness of diversity as a way to combat the irreducible error floor due to co-channel interference in fading channels. Calculation of the channel cut-off rate provides guidelines for the design of coded systems in such an environment.
4 citations
18 Jun 1995
TL;DR: Comparing coded and pragmatic-coded modulation based on orthogonal signal sets with non-coherent detection over an independent flat Rician fading channel proves that the latter is competitive even for practical designs and for AWGN channels.
Abstract: We compare the performance of coded and pragmatic-coded modulation based on orthogonal signal sets with non-coherent detection over an independent flat Rician fading channel. Computation of the channel cut-off rate shows that, in this case, pragmatic-coded modulation is superior to coded modulation. By deriving bit error probabilities for actual coded and pragmatic-coded modulation schemes, we prove that the latter is competitive even for practical designs and for AWGN channels.
2 citations
14 Nov 1995
TL;DR: By deriving a necessary and sufficient condition for the existence of an error floor, it is shown that, when the fading is not slow, it always exists, and decreases exponentially with the product of code diversity and space diversity.
Abstract: We present an analysis of coded modulation with block differential detection in a correlated Rician fading channel with space diversity. Coded differential PSK is included in our analysis as a special case. Through cut-off rate analysis we compare different coded channels resulting from the choice of the block length N and the diversity order M with slow fading. With fast fading, the simple branch metric considered is not maximum-likelihood. By deriving a necessary and sufficient condition for the existence of an error floor, we show that, when the fading is not slow, it always exists, and decreases exponentially with the product of code diversity and space diversity.
2 citations
Patent•
02 Aug 1995
TL;DR: In this paper, the authors propose a system that concerne a Systeme de transmission de signaux radioelectriques via un satellite de communication geostationnaire principal (MS) and un ou plusieurs satellites auxiliaires (DSR1 ) "co-localises" sur la meme orbite, en diversite spatiale.
Abstract: Linvention concerne un Systeme de transmission de signaux radioelectriques via un satellite de communication geostationnaire principal (MS) et un ou plusieurs satellites auxiliaires (DSR1 ) "co-localises" sur la meme orbite, en diversite spatiale. La distance separant un satellite auxiliaire (DSR1 ) du satellite principal (MS) est comprise dans une gamme de 200 a 400 km. Le systeme comprend des liens de transmission bidirectionnels classiques (lm0 -ld0 , lbi ) entre des terminaux terrestres mobiles (MTu ) et le satellite principal (MS) et entre celui-ci et une station terrestre (ST1 ). En outre des liens de transmission unidirectionnels (lm1 , ll0 ) sont prevus entre les satellites auxiliaires (DSR1 ) et le satellite principal (MS). Application notamment a un service de communication mobile avec des terminaux portables via un satellite geostationnaire.
2 citations