In this paper, we focus on the multi-way relaying channel where K users wish to exchange information with each other within two phases. Precoding at each user and the relay is carefully constructed to ensure that the signals from the same user pair are grouped together and cross-pair interference can be cancelled. Reliable detection is challenging at the relay since the observation constellation is no longer one of the regular ones, due to the fact that a relay observation is the superposition of the messages from one of the $rac{1}{2}K(K-1)$ user pairs. When the trellis coded modulation is used at each node, a simple constellation mapping function and a reduced-states decoding scheme can be applied at the relay, which result in much lower complexity. Furthermore, a modified version of the decoding method is also developed which is called the re-encoding-avoidance scheme at the relay. Monte-Carlo simulation results are provided to demonstrate the performance of the proposed scheme.

A Generalized Symbol-rate-increased (GSRI) Pragmatic Adaptive Trellis Coded Modulation (ATCM) is applied to a Multi-carrier CDMA (MC-CDMA) system with bi-orthogonal keying is analyzed. The MC-CDMA considered in this paper is that the input sequence of a bi-orthogonal modulator has code selection bit sequence and sign bit sequence. In, an efficient error correction code using Reed-Solomon (RS) code for the code selection bit sequence has been proposed. However, since BPSK is employed for the sign bit modulation, no error correction code is applied to it. In order to realize a high speed wireless system, a multi-level modulation scheme (e.g. MPSK, MQAM, etc.) is desired. In this paper, we investigate the performance of the MC-CDMA with bi-orthogonal keying employing GSRI ATCM. GSRI TC-MPSK can arbitrarily set the bandwidth expansion ratio keeping higher coding gain than the conventional pragmatic TCM scheme. By changing the modulation scheme and the bandwidth expansion ratio (coding rate), this scheme can optimize the performance according to the channel conditions. The performance evaluations by simulations on an AWGN channel and multi-path fading channels are presented. It is shown that the proposed scheme has remarkable throughput performance than that of the conventional scheme.

For more efficient data transmissions, a new MLP/BP-based channel equalizer is proposed to compensate for multi-path fading in wireless applications. In this work, for better system performance, we apply the soft output and the soft feedback structure as well as the soft decision channel decoding. Moreover, to improve packet error rate (PER) and bit error rate (BER), we search for the optimal scaling factor of the transfer function in the output layer of the MLP/BP neural networks and add small random disturbances to the training data. As compared with the conventional MLP/BP-based DFEs and the soft output MLP/BP-based DFEs, the proposed MLP/BP-based soft DFEs under multi-path fading channels can improve over 3-0.6 dB at PER=10-1 and over 3.3-0.8 dB at BER=10-3.

The letter presents an analysis of bit error probability for trellis coded 8-ary phase shift keying moduation with 2-state soft decision Viterbi decoding. It is shown that exact numerical error performance can be obtained for low singal-to-noise power ratio where bounds are useless.

A Generalized Symbol-rate-increased (GSRI) Pragmatic Trellis coded Type-I Hybrid ARQ based on a Selective-Repeat (SR) ARQ with multicopy (MC) retransmission (SR+MC scheme) for high speed mobile satellite communication system is analyzed. The SR+MC ARQ is a suitable scheme for mobile satellite systems and further improvement of the throughput performance can be expected by an additional combination of an error control coding. In this paper, we investigate the performance of the SR+MC scheme employing GSRI Pragmatic TCM. GSRI TC-MPSK can arbitrarily set the bandwidth expansion ratio keeping higher coding gain than conventional TCM scheme. Also Pragmatic TCM has an advantage in that the modulation level can be easily changeable. By changing the modulation level and the bandwidth expansion ratio, this scheme can optimize the performance according to the channel conditions. Numerical and simulation results show that the GSRI Trellis Coded Type-I Hybrid ARQ presents better performance than conventional Pragmatic Trellis Coded Type-I Hybrid ARQ.

Reduced-state sequence estimation (RSSE) for trellis-coded modulation (TCM) in cyclic prefixed single carrier (CPSC) with minimum mean-square error-linear equalization (MMSE-LE) on frequency-selective Rayleigh fading channels is proposed. The Viterbi algorithm (VA) is used to search for the best path through the reduced-state trellis combined equalization and TCM decoding. Computer simulations confirm the symbol error probability of the proposed scheme.

Recently, space-time multiple trellis coded modulation (ST-MTCM) has been introduced in order to achieve maximum transmit diversity gain and larger coding gain with the existance of parallel paths, which can not be achieved with STTCM system. In order to achieve good performance, it is crucial to maximize the intra-distance, which is defined by parallel paths and determine the performance. Conventional ST-MTCM uses a generator matrix G for coded modulation; however, we find that no matrix can be designed which can maximize the intra-distance by computer search. In this paper, we focus on maximizing the intra-distance and the diversity gain, and hence design a new coded modulation scheme. We use trellis codes in this paper which cannot be described by a matrix G. The proposed codes can achieve the maximum intra-distance and thus good coding gain, which may not be achieved by conventional codes. We also show that the proposed code can achieve good performance both in quasi-static and fast flat fading channels without the need for changing the codes as is necessary in the conventional ST-MTCM scheme.

In this letter, we describe an adaptive hybrid SR ARQ scheme using punctured TCM and code combining. Numerical results show that the proposed scheme yields better throughput efficiency than the scheme using TCM at the values of Es/No smaller than 9 dB.

GSRI Pragmatic TCM, which is a Pragmatic Trellis Coded Modulation allowing bandwidth expansion, has been proposed. In [1], it is shown that this scheme can achieve higher performance than conventional Pragmatic TCM scheme. On the other hand, a real-time video multimedia communication is one of the possible applications for the third generation mobile communication systems. This video multimedia communication system needs a multiplexer which mixes various types of media such as video, voice and data into a single bitstream. ITU-T has standardized H.223 Annex A, B, C and D multimedia multiplexing protocols for low bit-rate mobile communications. This paper evaluates the performance of the GSRI Pragmatic TCM with an application of a mobile multimedia system using H.223 Annex D multiplexing scheme and MPEG-4 video coding.

A Pragmatic Trellis Coded MPSK on a Rayleigh fading channel is analyzed. This scheme allows bandwidth expansion ratio to be varied aiming at an optimization between complexity of the system design and improvement of coding gain. In order to vary the bandwidth expansion ratio, a punctured convolutional code is used. The performance of the proposed TC-2mPSK on a Rayleigh fading channel is theoretically analyzed. In the test examples, the BER performances of TC-QPSK and TC-8PSK are evaluated by theoretical analyses and computer simulations at the encoder parameters of K3 and r3/4. The results show that the proposed scheme can attain better performance not only over the uncoded scheme but over the conventional Pragmatic TCM.

We propose an improved orthogonal frequency division multiplexing (OFDM) signal detector which uses the minimum mean-square error (MMSE) noise feedback equalization (NFE). The input bit stream is trellis-coded to form OFDM signal blocks and the maximal ratio combining (MRC) is adopted at the receiver in order to improve the performance of the detector. As a result, we obtain significantly improved detection performance compared with the conventional OFDM receivers as follows. Using the proposed MMSE-NFE in the receiver, we can obtain the performance gain of about 1.5 dB to 2 dB in symbol energy to noise power spectral density (Es/No) for Doppler frequencies of fd=20 and 100 Hz, respectively, over the receiver with the MMSE linear equalization (LE) alone at symbol error rate (SER) of about 10-3. With MRC and trellis coding, the performance gain of about 11 dB in Es/No for fd=20 and 100 Hz at SER of about 10-3 is obtained.

For L 2, M 8, and transmission rate R = (log2M-1) bit/sym, a method for constructing GU trellis codes with L MPSK constellations is proposed and it is shown that the maximally achievable free distance is twice larger than it was previously reported for GU codes. Basides being geometrically uniform, these codes perform as good as Pietrobon's non-GU trellis codes with multidimensional MPSK constellations.

We have investigated the BER performance of TC 8PSK with 2 branch SC and MRC diversities on spatially correlated Rayleigh fading channel. The upper bounds using the transfer function bounding technique are derived several numerical results are shown. Although the correlation between branches causes signal-to-noise (SNR) loss (relative to uncorrelated fading case) for SC and MRC diversities, the diversity can lead to achieve the diversity gain compared to the system without diversity. It is found that the diversity gain of 4-state TC 8PSK is larger than 8-state TC 8PSK. It is also shown that the BER performance of TC 8PSK is decreased as the antenna separation is decreased.

A channel coding which combines convolutional coding and M-ary PSK/orthogonal multi-carrier (MPSK/OMC) transmission is proposed. A coding gain is achieved without sacrificing the data rate or occupying extra bandwidth. The proposed coding formula is that the imformation data bits of bit interval Ts are serial to parallel converted to P parallel branches where each branch has a bit interval Tp = PTs. The data bits of the parallel branches are encoded through a rate nP/(n + 1)(2P - 1) convolutional encoding process and the total (n+1)(2P-1) symbol of the encoder output is transmitted by 2P - 1 OMCs where each carrier is modulated by MPSK/OMC (M = 2n + 1). Following performance analysis of a coding form using rate P/(2P - 1) convolutional encoder and BPSK/OMC modulation, a general channel coding combining convolutional coding and MPSK/OMC modulation is discussed.

In conventional trellis coded modulation (TCM), higher-ary modulation scheme combining with a convolutional code is employed not to expand the transmitted bandwidth. This forces the system to be attended with signal constellation expansion and increasing the average signal power. As the solutions to avoid signal constellation expansion, TCM systems using totally overlapped signal sets (TO-TCM and RU-TCM) were proposed. These schemes can realize a coded modulation system without signal constellation expansion and achieve more coding gain compared with the conventional TCM. However, a problem that the systems with totally overlapped signal sets might be catastrophic has been remained. In this paper, we propose a novel TCM system using partially overlapped signal sets of non-equiprobable signaling (PO-TCM-NE). This scheme employs the partially overlapped signal constellation to control increasing signal points, and to avoid catastrophic error propagation. The non-equiprobable signaling is employed to reduce average signal power. Coding gain of the proposed PO-TCM-NE is considerably improved in consequence the average signal power is reduced much lower than that of other TCM systems with equiprobable signaling.

Co-channel interference is a major factor limiting spectral efficiency of a cellular radio system. The trellis-coded co-channel interference canceller (TCC) leading to the significant increase of traffic capacity of a cellular system has been proposed. In this scheme, a maximum-likelihood sequence estimation implemented with the Viterbi algorithm is extended to estimate both desired signal and co-channel interference, and combined with trellis-coded modulation to enhance the co-channel interference cancelling capability. The complexity of TCC grows exponentially with the channel memory and the constraint length of the trellis encoder. In this paper, two reduced-state sequence estimation algorithms, namely, the delayed decision feedback sequence estimation and the M-algorithm, are applied to TCC and their performance is compared. In addition, effective trellis coded modulation schemes to reduce the computational complexity are proposed. The performance of these schemes is examined through simulations, and compared to that of a conventional interference canceller.

The performance of trellis coded hybrid frequency and phase shift modulation (TC HFPSK) with the expurgated phase code and the asymmetric signal constellation is investigated by using the minimum squared free Euclidean distance d 2free and the bit error rate (BER). It is found that TC hybrid 2FSK/4PSK with the expurgated phase code shows larger d 2free than the corresponding TC hybrid 2FSK/4PSK with the complete phase code for varying the angle φ that determines the asymmetric signal constellation. The maximum value of d 2free of TC hybrid 2FSK/4PSK with the expurgated phase code can be obtained when the signal constellation is symmetric. The performance of BER is analyzed in additive white Gaussian noise (AWGN) and fading channels by using uniform error property and error bound based on transfer function. It is found that the coding gain of TC hybrid 2FSK/4PSK with the expurgated phase code over uncoded hybrid 2FSK/2PSK at BER=10-4 are 2.71dB and 4.74dB in AWGN and fading channels, respectively. The performance improvements of TC hybrid 2FSK/4PSK with the expurgated phase code over TC 8PSK at BER=10-4 are 0.68dB and 4.07dB in AWGN and fading channels, respectively.

In this paper, a design of TCM signals for Middleton's class-A impulsive noise environment is investigated. The error event characteristics under the impulsive noise is investigated, and it is shown that the length of the signal sequence is more important than Euclidean distance between the signal sequences. Following this fact, we introduce the shortest error event path length as a measure of the signal design. In order to make this value large, increasing of states of convolutional codes is employed, and the performance improvement achieved by this method is evaluated. Numerical results show the great improvement of the error performance and conclude that the shortest error event path length is a good measure in the design of TCM signals under impulsive noise environment. Moreover, the capacity of class-A impulsive noise channel is evaluated, and the required signal sets expansion rates to obtain the achievable coding gain is discussed.

In this paper we analize the performance of Trellis Coded Modulation (TCM) schemes with coherent detection operating in a frequency flat, mobile Rayleigh fading environment, and with different knowledge levels on both the amplitude and phase fading processes (the latter is not assumed as usual to be ideally tracked), or Channel State Information (CSI). For example, whereas ideal CSI means that both the amplitude and phase fading characteristics are perfectly known by the receiver, other situations that are treated consider perfect knowledge of the amplitude (or phase) with complete disregard of the phase (or amplitude), as well as non concern on any of them. Since these are extreme cases, intermediate situations can be also defined to get extended bounds based on Chernoff which allow the phase errors, in either form of constant phase shifts or randomly distributed phase jitter, to be included in the upper bounds attainable by transfer function methods, and are applicable to multiphase/level signaling schemes. We found that when both fading characteristics are considered, the availability of CSI enhances significatively the performance. Furthermore, for non constant envelope schemes with non ideal CSI and for constant envelope schemes with phase errors, an asymmetry property of the pairwise error probability is identified. Theoretical and simulation results are shown in support of the analysis.

The performance evaluation by analysis of systems employing Reduced State Viterbi decoding is addressed. This type of decoding is characterized by an inherent error propagation effect, which yields a difficulty in the error probability analysis, and has been usually neglected in the literature. By modifying the Full State trellis diagram, we derive for Reduced State schemes, new transfer function bounds with the effects of error propagation. Both the Chernoff and the tight upper bound are applied to the transfer function in order to obtain the bit error probability upper bound. Furthermore, and in order to get a tighter bound for Reduced State decoding schemes with parallel transitions, the pairwise probability of the two sequences involved in an error event is upper bounded, and then the branch metric of a sequence taken from that bound is associated with a truncated instead of complete Gaussian noise probability density function. To support the analysis, particular assessment is done for a Trellis Coded Modulation scheme.