Turbo Trellis Coded Modulation Research Articles

Space-Time Turbo Trellis Coded Modulation for Wireless Data Communications

This paper presents the design of space-time turbo trellis coded modulation (ST turbo TCM) for improving the bandwidth efficiency and the reliability of future wireless data networks. We present new recursive space-time trellis coded modulation (STTC) which outperform feedforward STTC proposed by Tarokh et al. (1998) and Baro et al. (2000) on slow and fast fading channels. A substantial improvement in performance can be obtained by constructing ST turbo TCM which consists of concatenated recursive STTC, decoded by iterative decoding algorithm. The proposed recursive STTC are used as constituent codes in this scheme. They have been designed to satisfy the design criteria for STTC on slow and fast fading channels, derived for systems with the product of transmit and receive antennas larger than 3. The proposed ST turbo TCM significantly outperforms the best known STTC on both slow and fast fading channels. The capacity of this scheme on fast fading channels is less than 3 dB away from the theoretical capacity bound for multi-input multi-output (MIMO) channels.

Turbo trellis code modulation using MQAM

The paper presents a kind of reasonable structure for implementing MQAM T-TCM based on the principles of turbo codes and TCM for the first time. It can also be expanded to PSK T-TCM system, and the corresponding decoding algorithm is derived. By computer simulation, its performance is analyzed. The results show that T-TCM takes the advantages of turbo codes and TCM technology, and is a kind of bandwidth-efficient coded-modulation technique obtaining high coding gain. So, in the future, T-TCM would be applied in many fields.

TTCM schemes based on time-varying trellis approach

An efficient time-varying trellis approach is proposed for turbo trellis coded modulation (TTCM). Using a time-varying trellis, the efficient free Euclidean distance is increased, thus improving the performance of TTCM. Experimental results show that the bit error rate (BER) of the proposed time-varying TTCM is better than that of the conventional TTCM scheme. Also, compared with an eight-state time-invariant TTCM scheme, a two-state time-varying TTCM scheme can achieve nearly the same BER performance.

Space-time IQ-interleaved TCM and TTCM for AWGN and Rayleigh fading channels

Space-time block coded inphase-quadrature phase (IQ)-interleaved trellis coded modulation (TCM) and turbo TCM (TTCM) schemes are proposed, which are capable of quadrupling the diversity order of conventional symbol-interleaved TCM and TTCM schemes. The increased diversity order of the proposed schemes provides significant coding gains, when communicating over non-dispersive Rayleigh fading channels without compromising the coding gain achievable over Gaussian channels.

Space-time turbo trellis coded modulation for wireless data communications

This paper presents the design of space-time turbo trellis coded modulation (ST turbo TCM) for improving the bandwidth efficiency and the reliability of future wireless data networks. We present ne...

Noncoherent iterative decoding of spectrally efficient coded modulations

In this paper, we consider possible solutions for noncoherent decoding of concatenated codes with spectrally efficient modulations. Two main classes of schemes are considered. A first class is obtained by concatenating parallel coding schemes with differential encoding. A second class considers serially concatenated coding structures and possible schemes derived from turbo trellis coded modulation (T-TCM), which do not employ differential encoding. In the first case, at the receiver side we consider separate detection and decoding, while in the second case we consider joint detection and decoding. The major problem connected with such an iterative decoding procedure is that taking into account an augmented channel memory leads to an intolerable trellis size, and hence to an impractical decoding complexity. Reduced-complexity techniques suited to iterative decoding become fundamental, and we consider a recently proposed state-reduction technique. This way, the performance of a coherent receiver is approached, by keeping the number of receiver states fixed.

Performance of DS/SSMA system using turbo TCM/FPM over multipath Rician fading channel

The synergy between frequency and phase modulation (FPM) using trellis-coded modulation (TCM) leads to greater gains than can be achieved using conventional TCM/MPSK modulation. An iterative structure is introduced into a TCM/FPM scheme to give a new scheme, the turbo TCM/FPM scheme. Simulation results show that the new scheme can achieve a significant performance improvement with respect to the turbo TCM 8PSK and TCM/FPM schemes, respectively, for a DS/SSMA system over a multipath Rician fading channel.

Joint trellis-coded quantisation/modulation

Joint trellis-coded quantisation (TCQ) and trellis-coded modulation (TCM) can achieve considerable signal-to-quantisation noise ratios with moderate complexity. TCM is replaced with turbo TCM (TTCM) and simulation results given which show that the new scheme can achieve the same performance as that possible using by trellis-coded scalar quantisation at an SNR slightly above the channel capacity bound.

DMT scheme with multidimensional turbo trellis code

Turbo codes can be naturally extended to bandwidth-efficient applications. A turbo code with powerful bandwidth-efficient component codes is investigated and its application in the discrete multitone environment is considered. Simulation results show that the multidimensional turbo trellis-coded modulation scheme can achieve outstanding performance even at relatively low signal-to-noise ratio.

Performance of turbo trellis-coded modulation (T-TCM) on frequency-selective Rayleigh fading channels

Turbo trellis-coded modulation (T-TCM) is one of several techniques for combining turbo codes with multilevel modulation schemes to save the bandwidths of the transmission systems. T-TCM has been shown to perform very well on AWGN channels, but its performance on frequency-selective fading channels is still unknown. A system model to investigate the performance of various T-TCM schemes on frequency-selective fading channels is proposed and simulation results show that when an appropriate receiver is available, T-TCM performs much better than any other known coded-modulation scheme for this type of channel.

Turbo TCM schemes for WCDMA systems

Three novel turbo TCM schemes, l/n TTCM, TTC-SPM and NP-TTC-SPM, are proposed. They are derived from the TTCM scheme but have better performance for use in WCDMA systems over fading channels. Simulation results are presented.