In this paper we provide a state space approach for constructing convolutional codes of rate 1/n and complexity delta, whose free distance is n(delta + 1), the maximal possible free distance.
ISBN:
(纸本)0780344081
In this paper we provide a state space approach for constructing convolutional codes of rate 1/n and complexity delta, whose free distance is n(delta + 1), the maximal possible free distance.
In this paper we derive computationally efficient minimality and canonicity tests for rational generator matrices for convolutional codes. The first set of tests are given in terms of easily obtained equivalent polyno...
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ISBN:
(纸本)0780344081
In this paper we derive computationally efficient minimality and canonicity tests for rational generator matrices for convolutional codes. The first set of tests are given in terms of easily obtained equivalent polynomial generator matrices and are suitable for small k and n. New tests are derived based on the scalar generator matrix G which are computationally more efficient for large k and n and small n. The application of these tests to generator matrices for (P)UM codes is studied. Finally, the results of [4] are extended to the enumeration of minimal and canonical rational generator matrices.
Using the principles of generalized concatenation we introduce a new design for encoded M-ary CPFSK systems with modulation index h = 1/M. This technique is based on a set partitioning method of inner CPFSK into neste...
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ISBN:
(纸本)0780344081
Using the principles of generalized concatenation we introduce a new design for encoded M-ary CPFSK systems with modulation index h = 1/M. This technique is based on a set partitioning method of inner CPFSK into nested subsystems with increasing free Euclidean distance. The subsystems are combined with several outer convolutional codes having different error-correcting capabilities. We describe a multistep decoding algorithm of generalized concatenated encoded CPFSK and give simulation results. The comparison of the generalized concatenated codes with the best known trellis-coded CPFSK schemes is also presented.
Continuous phase modulation (CPM) is known for its attractive spectral properties. Furthermore, CPM has the property that the modulation signal maintains a Constant envelope, so CPM is effective for satellite communic...
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Continuous phase modulation (CPM) is known for its attractive spectral properties. Furthermore, CPM has the property that the modulation signal maintains a Constant envelope, so CPM is effective for satellite communications. Recently, generalized nonlinear CPM (GNCPM), which can achieve a larger minimum Euclidean distance than ordinary CPM, was introduced. In this paper, we propose a convolutional coded GNCPM to improve the bit error rate (BER) performance of uncoded GNCPM without expanding bandwidth. Combination CPM with convolutional coding causes an increased number of phase trajectory patterns which can cause the bandwidth expansion. Therefore, in our proposed model, to control the bandwidth, we pay attention to the phase trajectory pattern which is already owned by:uncoded GNCPM and change the modulation index approximately, depending on the input symbols, to keep the number of phase trajectory patterns the same as in uncoded GNCPM. First, we consider the most suitable assignment of the modulation index which can increase the Euclidean distances without bandwidth expansion. Next, we theoretically derive the upper bound on the error event probability of the proposed model in additive white Gauss lan noise (AWGN). The performance of the proposed convolutional GNCPM, obtained by computer simulation, shows that the proposed model can improve BER performance without bandwidth expansion. (C) 1998 Scripta Technica.
Coded Orthogonal frequency division multiplexing(COFDM) is a robust technique in fading *** this paper,higher modulation schemes are considered with OFDM for a Rician fading ***,convolutional coding(CC) and Trellis co...
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Coded Orthogonal frequency division multiplexing(COFDM) is a robust technique in fading *** this paper,higher modulation schemes are considered with OFDM for a Rician fading ***,convolutional coding(CC) and Trellis coded modulation(TCM) are combined with *** error rate (BER) performances are analyzed with L and Ka frequency *** coded OFDM(TCM-OFDM) gives a better performance compared to convolutional coded OFDM(CC-OFDM) with a lower trellis *** also the performance does not depend significantly on the frequency band.
In this paper, we deal with convolutionally encoded MSK, DMSK and TFM signals. The matched convolutional encoding technique is used which was shown earlier to lead in some cases to the optimum Viterbi demodulation/dec...
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In this paper, we deal with convolutionally encoded MSK, DMSK and TFM signals. The matched convolutional encoding technique is used which was shown earlier to lead in some cases to the optimum Viterbi demodulation/decoder which is not more complex than the optimum receiver for the uncoded signal. Results of a systematic search for such cases are presented and discussed.
This paper develops a reduced-complexity online state sequence and parameter estimator for superimposed convolutional coded signals, Joint state sequence and parameter estimation is achieved by iteratively estimating ...
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This paper develops a reduced-complexity online state sequence and parameter estimator for superimposed convolutional coded signals, Joint state sequence and parameter estimation is achieved by iteratively estimating the state sequence via a variable reduced-complexity Viterbi algorithm (VRCVA) and the model parameters via a recursive expectation maximization (EM) approach, The VRCVA is developed from a fixed reduced-complexity Viterbi algorithm (FRCVA), The FRCVA is a special case of the delayed decision-feedback sequence estimation (DDFSE) algorithm, The performance of online versions of the FRCVA, VRCVA, and the standard Viterbi algorithm (VA) are compared when they are used to estimate the state sequence as part of the reduced-complexity online state sequence and parameter estimator.
The main drawback of sequential decoding is the variability of its decoding effort which could cause decoding erasures. We propose and analyze in this correspondence an efficient bidirectional sequential decoding (BSD...
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The main drawback of sequential decoding is the variability of its decoding effort which could cause decoding erasures. We propose and analyze in this correspondence an efficient bidirectional sequential decoding (BSD) technique to alleviate this drawback. In the proposed BSD, two decoders are used;one is called a forward decoder (FD), and is used to search the tree from forward direction;while the other is called a backward decoder (ED), and is used for the backward search of the tree. Forward decoding and backward decoding are performed simultaneously, and stop whenever FD and ED merge at a common encoder state somewhere in the tree. The relationships between backward coding and forward coding are examined in detail. Good rate 1/2 convolutional codes, with memory m ranging from 2 to 25, suitable for bidirectional decoding found through extensive computer search, are provided. These codes possess the same distance properties from both forward and backward directions. It is found by means of extensive computer simulations as well as a heuristic argument that the advantage of BSD appears as a substantial decrease of the computational variability of sequential decoding. Our findings suggest that the Pareto exponent of unidirectional sequential decoding (USD) can be practically doubled by using BSD.
This paper proposes and evaluates a new co-channel interference cancellation technique that utilizes orthogonal convolutional codes on a multipath Rayleigh fading channel, In a spread spectrum multiple access environm...
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This paper proposes and evaluates a new co-channel interference cancellation technique that utilizes orthogonal convolutional codes on a multipath Rayleigh fading channel, In a spread spectrum multiple access environment, co-channel interference (CCI) limits the performance of the communication link, To remove this interference, several CCI cancellation techniques have been proposed, including the technique that does not require the receiver to have knowledge of the cross-correlation between user sequences, This method leaves residual interference after the cancellation caused by errors in the initial decisions, To reduce the residual interference and improve the initial decisions, the proposed scheme utilizes the error-correcting capability of orthogonal convolutional codes, This paper evaluates the performance of this scheme, Our results show that the proposed CCI canceller offers all improvement in capacity by a factor of 1.5 similar to 3 as compared with a conventional canceller on a multipath Rayleigh fading channel, The proposed canceller works in the presence of residual interference due to imperfect cancellation, The proposed canceller also has a capacity improvement with the use of soft handoff in a multicell configuration.
作者：
Hole, KJLaboratory of Chromatography
DEPg.Fac.Quimica Universidad Nacional Autonoma de Mexico Circuito interior Cd Universitaria/CP 04510 Mexico D.F.Mexico
Many classes of rate (n - 1)/n convolutional codes are shown to be asymptotically catastrophic.
Many classes of rate (n - 1)/n convolutional codes are shown to be asymptotically catastrophic.
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