Multilevel Coded Modulation System Research Articles

Multi-Level Coded Modulation for 16-ary Constellations in Presence of Phase Noise

Application of multi-level coded modulation (MLCM) for 16-ary constellations in coherent systems is studied. An MLCM system with Reed-Solomon component codes and multi-stage decoder is considered. A systematic numerical method for finding set-partitioning and optimal code rates is presented. The method only requires the probability density function of received samples and can be applied to any constellation regardless of irregularity or lack of symmetry. Performance of the designed MLCM system is verified in presence of nonlinear phase noise and normal phase noise. For nonlinear phase noise limited system, it is shown that the block error rate (BLER) of the system can be improved using our approach for set-partitioning. For phase noise limited system, both BLER and bit error rate (BER) are studied for a phase noise optimized and square 16-quadrature amplitude modulation (16QAM). Post forward-error correction (FEC) BER performance of the optimized constellation over square 16QAM is studied for different levels of phase noise. It is shown that the optimized constellation along with MLCM system decreases the required signal-to-noise ratio by several dB at high phase noise regime and low post FEC BER.

On the Dimensionality of Multilevel Coded Modulation in the High SNR Regime

In this paper, the dimensionality of the multilevel coded modulation (MLCM) scheme is addressed. This study is done for an MLCM scheme with a N-dimensional (ND) constellation constructed from the Cartesian product of N identical 1D constellations in the high SNR regime. It is demonstrated that multidimensional MLCM with Reed-Solomon code components has better trade-off between coding gain and complexity than a 1D scheme. Specifically, a 4D MLCM system gains 1.4 dB over a 1D MLCM system with lower complexity at a block error of 10-6. The gain increases to 2.5 dB asymptotically.

Analysis, implementation and application of an ordered statistics decoder for the seRS(16,14) code

The authors present an analysis and the FPGA implementation of an ordered statistics decoder for the singly extended Reed–Solomon code seRS(16,14). The goal of the design is to maintain good performance while reducing computational complexity and area with respect to the maximum-likelihood decoder of the same code or a Viterbi decoder of a high-rate punctured convolutional code of comparable performance. The authors also analyse a multilevel coded modulation system based on the partition chain E8/RE8/2E8, that makes use of a rate-1/2 16-ary convolutional code at the first level and of the seRS(16,14) code at the second level. This scheme is well suited to STM1 data transmission (155.52 Mbit/s) with 28 MHz channel spacing and 256 QAM modulation.

Asymptotical analysis and comparison of two coded modulation schemes using PSK signaling .II

For pt.I see ibid., vol.47, no.7, p.2782-92 (2001). In this paper we analyze a multilevel coded modulation system using phase-shift keying (PSK) signaling and transmitting over the additive white Gaussian noise (AWGN) channel. We reduce the analysis of the overall system to the analysis of each decoding level, considering them as a set of related channels. The concept of a "genie-aided communication system" is introduced to simplify the analysis. A comparison with the conventional coded modulation system, studied in part I of this work, and some results concerning the synthesis and analysis of practical multilevel modulation schemes concludes the paper.

Performance analysis of multilevel coded modulation system with finite interleaving for fading channel

In order to analytically evaluate the characteristics of the multilevel coding method using finite interleaving for a fading communication channel, an evaluation method for coding performance is proposed. In this method, the error rate of PSK after passing through a fading communication channel in which the gain variations at different times are statistically not independent is approximated by a Markov model. The state transition probability and the transfer gain of the Markov model are optimized by the use of a genetic algorithm. Next, the characteristic evaluation equation of the multilevel coding method for this Markov approximation model is derived. In this derivation, the characteristic evaluation equation is derived in the following way. The generation probability of the error in each level is derived as a function of the number of generations of the states in the section of the coding length and the error rate is averaged by the state generation probability. With this evaluation equation, the error rate after decoding with finite interleaving is derived and the optimum coding method is clarified. © 2000 Scripta Technica, Electron Comm Jpn Pt 3, 84(2): 65–75, 2001

Analysis and implementation of an adjustable-rate multilevel coded modulation system

The authors describe the design of a multilevel coded modulation system. The main goal is to achieve a high degree of rate flexibility, with the same hardware allowing for the implementation of several coded schemes. This is obtained by associating a hierarchy of punctured convolutional codes with the partition chain of a square-lattice signal constellation. After discussing the rationale behind their design choices and implementation details, the authors analyse the system by computing its error probabilities, and show experimental results.

Performance analysis of a multilevel coded modulation system

A modified version of the multilevel coded modulation scheme of Imai and Hirakawa (1977) is presented and analyzed. In the transmitter, the outputs of the component codes are bit interleaved prior to mapping into 8-PSK channel signals. A multistage receiver is considered, in which the output amplitudes of the Gaussian channel are soft limited before entering the second and third stage decoders. Upper bounds and Gaussian approximations for the bit error probability of every component code, which take into account errors in previously decoded stages, are presented. Aided by a comprehensive computer simulation, it is demonstrated in a specific example that the addition of the interleaver and soft limiter in the third stage improves its performance by 1.1 dB at a bit error probability of 10/sup /spl minus/5/, and that the multilevel scheme improves on an Ungerboeck's code with the same decoding complexity. The rate selection of the component codes is also considered and a simple selection rule, based on information theoretic arguments, is provided.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>