Joint Multilevel Turbo Equalization and Continuous Phase Frequency Shift Keying

A novel type of turbo coded modulation scheme, called multilevel turbo coded-continuous phase frequency shift keying (MLTC-CPFSK), is designed to improve the overall bit error rate (BER) and bandwidth efficiency. Then, this scheme is combined with a new double decision feedback equalizer (DDFE) to remove the interference and to enhance BER performance for the intersymbol interference (ISI) channels. The entire communication scheme is called multilevel turbo equalization-continuous phase frequency shift keying (MLTEQ-CPFSK). In these schemes, parallel input data sequences are encoded using the multilevel scheme and mapped to CPFSK signals to obtain a powerful code with phase continuity over the air. The performances of both MLTC-CPFSK and MLTEQ-CPFSK systems were simulated over nonfrequency and frequency-selective channels, respectively. The superiority of the two level turbo codes with 4CPFSK modulation is shown against the trellis-coded 4CPFSK, multilevel convolutional coded 4CPFSK, and TTCM schemes. Finally, the bit error rate curve of MLTEQ-CPFSK system over Proakis B channel is depicted and ISI cancellation performance of DDFE equalizer is shown against linear and decision feedback equalizers </p

Joint Multilevel Turbo Equalization and Continuous Phase Frequency Shift Keying

A novel type of turbo coded modulation scheme, called multilevel turbo coded-continuous phase frequency shift keying (MLTC-CPFSK), is designed to improve the overall bit error rate (BER) and bandwidth efficiency. Then, this scheme is combined with a new double decision feedback equalizer (DDFE) to remove the interference and to enhance BER performance for the intersymbol interference (ISI) channels. The entire communication scheme is called multilevel turbo equalization-continuous phase frequency shift keying (MLTEQ-CPFSK). In these schemes, parallel input data sequences are encoded using the multilevel scheme and mapped to CPFSK signals to obtain a powerful code with phase continuity over the air. The performances of both MLTC-CPFSK and MLTEQ-CPFSK systems were simulated over nonfrequency and frequency-selective channels, respectively. The superiority of the two level turbo codes with 4CPFSK modulation is shown against the trellis-coded 4CPFSK, multilevel convolutional coded 4CPFSK, and TTCM schemes. Finally, the bit error rate curve of MLTEQ-CPFSK system over Proakis B channel is depicted and ISI cancellation performance of DDFE equalizer is shown against linear and decision feedback equalizers Copyright (C) 2008 Oguz Bayat et al

Multilevel Turbo Coded-Continuous Phase Frequency Shift Keying (MLTC-CPFSK) over satellite channels in space communication

In this paper, in order to improve bit error performance and bandwidth efficiency, we introduce a new type of Turbo coded modulation scheme, called Multilevel Turbo Coded-Continuous Phase Frequency Shift Keying (MLTC-CPFSK). The basic idea of multilevel coding is to partition a signal set into several levels and to encode separately each level by a proper component of the encoder. In MLTC-CPFSK, to provide phase continuity of the signals, Turbo encoder and Continuous Phase Encoder (CPE) are serially concatenated at the last level, while all other levels consist of only a turbo encoder. Therefore, the proposed system contains more than one turbo encoder/decoder blocks in its structure. The parallel input data sequences are encoded by our multilevel scheme and mapped to CPFSK signals. Then these modulated signals are passed through AWGN and fading channels. At the receiver side, input sequence of first level is estimated from the first turbo decoder. Then the other input sequences are computed using the estimated input bit streams of previous levels. Simulation results are drawn for 4CPFSK two-level turbo codes over AWGN, Rician, and Rayleigh channels for three iterations while frame sizes are chosen as 100 and 1024. Higher error performances are obtained from various type of MLTC-CPFSK systems compared to Trellis Coded CPFSK systems

Multilevel turbo coded-continuous phase frequency shift keying (MLTC-CPFSK)

In this paper, we introduce a Turbo coded modulation scheme, called multilevel turbo coded-continuous phase frequency shift keying (MLTC-CPFSK). The underlying basis of multilevel coding is to partition a signal set into several levels and to encode separately each level through the respective layer of the encoder. In MLTC-CPFSK, to provide phase continuity of the signals, turbo encoder and continuous phase encoder (CPE) are serially concatenated at the last level, while all other levels consist of only a turbo encoder. Therefore, the proposed system contains multiple turbo encoder/decoder blocks in its architecture. The parallel input data sequences are encoded by our multilevel scheme and mapped to CPFSK signals. Then, for the purpose of performance analysis, these modulated signals are passed through AWGN and fading channels. At the receiver side, the input sequence of the first level is estimated by the first turbo decoder block. Subsequently, the other input sequences of other levels are computed using the estimated input bit streams of the respective previous levels. Simulation results are drawn for 4-ary CPFSK two level and 8-ary CPFSK three level turbo codes over AWGN, Rician, and Rayleigh channels for three iterations while frame sizes are chosen as 100 and 1024. It is concluded that satisfactory performance is achieved in MLTC-CPFSK systems for all SNR values in various fading environments. (C) 2008 Elsevier Ltd. All rights reserved