Improved space-time trellis coded modulation scheme on slowRayleigh fading channels

It has been established that the appropriate criteria for space-time trellis coded modulation (STTCM) design on slow Rayleigh fading channels are maximisation of the minimum rank and the minimum determinant of the distance matrices. It is demonstrated that when STTCM is used in systems with a large product (>3) of the numbers of transmit and receive antennas, the design of codes with maximum coding gain is governed by the minimum trace of the distance matrices. A number of new codes based on the proposed design criterion have been constructed and shown to be superior to other known codes     

Concatenated space-time block coding with trellis coded modulation in fading channels

Trellis coded modulation (TCM) is a bandwidth efficient transmission scheme that can achieve high coding gain by integrating coding and modulation. This paper presents an analytical expression for the error event probability of concatenated space-time block coding with TCM which reveals some dominant factors affecting the system performance over slow fading channels when perfect interleavers are used. This leads to establishing the design criteria for constructing the optimal trellis codes of such a concatenated system over slow flat fading channels. Through simulation, significant performance improvement is shown to be obtained by concatenating the interleaved streams of these codes with space-time block codes over fading channels. Simulation results also demonstrate that these trellis codes have better error performance than traditional codes designed for single-antenna Gaussian or fading channels. Performance results over quasi-static fading channels without interleaving are also compared in this paper. Furthermore, it is shown that concatenated space-time block coding with TCM (with/without interleaving) outperforms space-time trellis codes under the same spectral efficiency, trellis complexity, and signal constellation.     

Novel high bit rate Viterbi decoder for monodimensional trellis coded modulation on fading channels

Describes a novel high bit rate Viterbi decoder for 4 AM and 8 AM trellis coded modulation optimised for a Rayleigh frequency selective channel.<>     

Multiple trellis coded frequency and phase modulation

Multiple trellis coded modulation of constant envelope frequency and phase modulated signal sets (MTCM/FPM) is investigated for performance on the additive white Gaussian noise (AWGN) channel and on the one-sided normal, Rayleigh and Rician fading channels. The Nakagami- m fading model is used as an alternative to the Rician fading model to calculate the error probability upper bound for trellis-coded schemes on the fading channel. The likeliness and the disparity between the upper bounds to the error probability for the two fading models are discussed. The design criteria for the one-sided normal fading channel, modeled by the Nakagami-m distribution, are observed to be the same as those for the Rayleigh-fading channel. For the MTCM/FPM schemes, it is demonstrated that the set partitioning designed to maximize symbol diversity (optimum for fading channels) is optimum for performance on the AWGN channel as well. The MTCM/FPM schemes demonstrate improved performance over MTCM/MPSK schemes and TCM/FPM schemes on the AWGN channel and the fading channel     

The design of trellis coded MPSK for fading channels: performancecriteria

It has been well established that the appropriate criterion for optimum trellis-coded modulation design on the additive white Gaussian noise channel is maximization of the free Euclidean distance. It is shown that when the trellis-coded modulation is used on a Rician fading channel with interleaving/deinterleaving, the design of the code of optimum performance is guided by other factors, in particular, the length of the shortest error-event path, and the product of branch distances (possibly normalized by the Euclidean distance of the path) along the path. Although maximum free distance (d_free) is still an important consideration, it plays a less significant role the more severe the fading is on the channel. These considerations lead to the definition of a new distance measure of optimization of trellis codes transmitted over Rician fading channels. If no interleaving/deinterleaving is used, then once again the design of the trellis code is guided by maximizing d_free      

Multidimensional trellis coded phase modulation using a multilevelconcatenation approach .II. Codes for the AWGN and fading channels

For pt.I see ibid., vol.45, no.1, p.64-72, 1997. We use the construction technique proposed in part I to construct multidimensional trellis coded modulation (TCM) codes for both the additive white Gaussian noise (AWGN) and the fading channels. Analytical performance bounds and simulation results show that these codes perform very well and achieve significant coding gains over uncoded reference modulation systems. In addition, the proposed technique can be used to construct codes which have a performance/decoding complexity advantage over the codes listed in literature     

Adaptive coded modulation for fading channels

We apply coset codes to adaptive modulation in fading channels. Adaptive modulation is a powerful technique to improve the energy efficiency and increase the data rate over a fading channel. Coset codes are a natural choice to use with adaptive modulation since the channel coding and modulation designs are separable. Therefore, trellis and lattice codes designed for additive white Gaussian noise (AWGN) channels can be superimposed on adaptive modulation for fading channels, with the same approximate coding gains. We first describe the methodology for combining coset codes with a general class of adaptive modulation techniques. We then apply this methodology to a spectrally efficient adaptive M-ary quadrature amplitude modulation (MQAM) to obtain trellis-coded adaptive MQAM. We present analytical and simulation results for this design which show an effective coding gain of 3 dB relative to uncoded adaptive MQAM for a simple four-state trellis code, and an effective 3.6-dB coding gain for an eight-state trellis code. More complex trellis codes are shown to achieve higher gains. We also compare the performance of trellis-coded adaptive MQAM to that of coded modulation with built-in time diversity and fixed-rate modulation. The adaptive method exhibits a power savings of up to 20 dB     

Design of trellis coded QAM for flat fading and AWGN channels

The design of trellis coded modulation (TCM) schemes for QAM constellations to counteract simultaneous flat fading and additive white Gaussian noise (AWGN) is considered. Motivated by the results of Divsalar and Simon (see IEEE Trans. Commun., vol.36, p.1004, 1988), and incorporating some recent ideas from Boulle and Belfiore (1992), we develop novel 2-D TCM schemes that attain diversity of order two even for a trellis structure that includes parallel paths with one symbol per edge. An algorithm is described that transforms codes designed for the AWGN channel into codes that achieve significant gains over flat fading channel, while preserving their coding gain over AWGN channel. Their performance is assessed via computer simulation for some representative TCM-QAM schemes under the assumption of uncorrelated fading and perfect channel state information (CSI). Finally, the effects of finite interleaving as well as imperfect CSI on code performance are investigated     

The performance of type-I trellis coded hybrid-ARQ protocols overAWGN and slowly fading channels

A method is described for modifying trellis coded modulation systems for use in type-1 hybrid-ARQ protocols. The difference between the partial path metric of the survivor and that of the best nonsurvivor at each node in the trellis is used to determine the desirability of a retransmission request for a given received packet. Bounds on the reliability and throughput performance of the resulting error control scheme are derived for AWGN channels and slowly fading Rician channels. Examples are included to illustrate the achievable gain of the proposed system relative to ordinary forward-error-correcting trellis coded systems. Hybrid-ARQ protocols based on ordinary trellis coded modulation and multiple trellis coded modulation are also compared over slowly fading Rician channels. The dependence of performance on packet length is examined and illustrated by examples. All analytical results are supported by data from a series of simulations     

A comparison of trellis coded and Reed-Solomon coded hybrid-ARQ protocols over slowly fading Rayleigh channels

The performance of trellis coded and Reed-Solomon coded ARQ error control systems over slowly fading Rayleigh channels are compared and contrasted in this paper. First, a two-code CRC-TCM type-I hybrid-ARQ scheme based on separate error correction and error detection codes is compared to a one-code Reed-Solomon protocol in which retransmission requests are generated within the decoding process. The performance of the associated packet combining protocols is also compared. It is shown that for similar levels of complexity, a onecode Reed-Solomon approach offers both better throughput and reliability performance than the TCM schemes in almost all cases.     

Universal serially concatenated trellis coded modulation for space-time channels

This paper presents serially concatenated trellis coded modulations (SCTCMs) that perform consistently close to the available mutual information for periodic erasure channel (PEC), periodic fading channel (PFC) and the 2 times 2 compound matrix channel. We use both the maximum-likelihood decoding criteria and iterative decoding criteria to design universal SCTCMs for the PEC and the PFC. For the space-time channel, by demultiplexing the symbols across the antennas, the proposed universal SCTCMs for the period-2 PFC deliver consistent performance over the eigenvalue skew of the matrix channel. Within the family of channels having the same eigenvalue skew, a time-varying linear transformation (TVLT) is used to mitigate the performance variation over different eigenvectors. The proposed space-time SCTCMs of 1.0, 2.0 and 3.0 bits per transmission require excess mutual information in the ranges 0.11-0.15, 0.23- 0.26 and 0.35-0.53 bits per antenna, respectively. Because of their consistent performance over all channels, the proposed codes will have good frame-error-rate (FER) performance over any quasi-static fading distribution. In particular, the codes provide competitive FER performance in quasi-static Rayleigh fading.     

Performance of trellis coded modulation schemes on shadowed mobilesatellite communication channels

The Canadian mobile satellite (MSAT) channel has been modeled as the sum of lognormal and Rayleigh components to represent foliage attenuation and multipath fading, respectively. Several authors have applied trellis coded modulation (TCM) schemes to this channel, estimating the bit error performance via computer simulation. In the present paper, analytical expressions are derived for the pairwise error probability (PEP) of TCM schemes over this channel under ideal interleaving. The analysis is applied to three detection strategies: ideal coherent detection, pilot-tone aided detection, and differential detection. The results are substantiated by means of computer simulation. In addition, first-order statistics of absolute and differential phases of a shadowed Rician process are examined     

Jitter and error performance analysis of trellis coded M-PSK overpartial response fading channels

For the first time, a partial response fading channel is introduced. The new channel model acts in a similar way to partial response signalling (PRS) with a Rayleigh probability density function. Emphasis is given to jitter and error performances of M-PSK schemes in the proposed channel with ideal channel state information, but with no side information existing on the phase noise process. Analytical upper bounds are derived using the Chernoff bounding technique, combined with the modified generating functional approach. Simulation studies confirming analytically obtained curves are carried out     

Symbol-level adaptive modulation for coded OFDM on block fading channels

It has recently been recognized by many researchers that adaptive modulation is most effective when the channel diversity order is small. In this letter, we propose a simple adaptive modulation scheme for orthogonal frequency division multiplexing (OFDM) systems on channels that provide a small order of diversity. The proposed adaptation algorithm is based on a novel and very simple analytical formula we derive for the performance of BICM on block fading channels. Simulation results show that the derived analytical formula is very tight when the targeted bit error probability is small. OFDM systems on indoor channels provide small orders of diversity and form an ideal scenario for adaptation. In order to keep system complexity and feedback requirements at a minimum, we will consider symbol-level adaptive modulation wherein all the subcarriers in an OFDM symbol use the same modulation.     

Trellis coded modulation schemes for shadowed Rician fading channels

The Canadian mobile satellite (MSAT) channel has been modelled as the sum of lognormal and Rayleigh components to represent foliage attenuation and multipath fading, respectively. The paper derives a Chernoff based error bound on the performance of trellis coded modulation (TCM) schemes operating on this channel.<>     

The design of trellis coded MPSK for fading channels: setpartitioning for optimum code design

A previous work on criteria for designing trellis-coded MPSK modulation to achieve minimum error probability performance on the Rician fading channel (see ibid., vol.36, no.9, p.1004-1012, Sep. 1988) is extended. It is demonstrated that allowing for multiple symbols per trellis branch, i.e., multiple trellis-coded modulation (MTCM), provides an additional degree of freedom for designing a code to meet the optimization on the fading channel. Diversities larger than those achievable with conventional trellis codes having the same number of trellis states are now attainable, it is under these conditions that MTCM achieves its full potential     

Performance of coded modulation employing differential encodingover Rayleigh fading channels

Multilevel coding and bit-interleaved coded modulation employing differential encoding and non-coherent reception over flat fading channels are assessed. To achieve high bandwidth efficiencies mixed amplitude/phase modulation is performed. It is shown that multiple symbol detection only provides gains for multilevel coding as Gray labelling of the differential symbols is not possible     

Union bounds on coded modulation systems over fast fading MIMO channels

Novel closed-form upper bounds on the error performance of coded modulation systems over fast-fading multi-input multi-output (MIMO) channels are obtained for two different space-time schemes: direct transmission and orthogonal space-time block codes. The concept of the distance spectrum for associated space-time codes is developed and used to derive the bounds which can be calculated readily through polynomial expansion. Comparison of the bounds for the two systems indicates the performance of direct transmission is superior. Comparison with simulation results shows that the bounds are tight and useful for benchmarking the practical iterative decoding process.     

Joint trellis coded quantization/modulation

A joint source/channel coding system constructed using trellis coded quantization (TCQ) and trellis coded modulation (TCM) is described. Identical trellises are used in the TCQ and TCM systems, and a straightforward mapping of TCQ codewords to TCM symbols is presented which guarantees that Euclidean squared distance in the channel is commensurate with quantization mean-square error (MSE). Hence, likely TCM error events of small Euclidean distance cause only a small increase in overall source coding MSE     

Concatenation of space‐time block codes and turbo trellis coded modulation (ST‐TTCM) over Rician fading channels with imperfect phase

In this paper, the performance of space time‐turbo trellis coded modulation (ST‐TTCM) is evaluated over Rician and Rayleigh fading channels with imperfect phase. We modify Baum–Welch (BW) algorithm to estimate the fading and phase jitter parameters for multi‐antenna configurations. Thus, we assume that the channel parameters change slower than carrier frequency. We know that, at high data rate transmissions over wireless fading channels, space–time block codes (STBC) provide the maximal possible diversity advantage. Here, the combined effects of the amplitude and the phase of the received signal are considered, each one modelled by Rician and Tikhonov distributions, respectively. We investigate space time‐turbo trellis coded modulation (ST‐TTCM) for 8‐PSK for several Rician factor K and phase distortion factor η. Thus, our results reflect the degradations both due to the effects of the fading on the amplitude and phase noise of the received signal while the channel parameters are estimated by BW algorithm. Copyright © 2004 John Wiley & Sons, Ltd.