The novel family of redundant residue number system (RRNS) codes is studied. RRNS codes constitute maximum-minimum distance block codes, exhibiting identical distance properties to Reed-Solomon codes. Binary to RRNS symbol-mapping methods are proposed, in order to implement both systematic and nonsystematic RRNS codes. Furthermore, the upper-bound performance of systematic RRNS codes is investigated, when maximum-likelihood (ML) soft decoding is invoked. The classic Chase algorithm achieving near-ML soft decoding is introduced for the first time for RRNS codes, in order to decrease the complexity of the ML soft decoding. Furthermore, the modified Chase algorithm is employed to accept soft inputs, as well as to provide soft outputs, assisting in the turbo decoding of RRNS codes by using the soft-input/soft-output Chase algorithm

Decision feedback equalizer (DFE)-aided turbo-coded wideband adaptive quadrature amplitude modulation (AQAM) is proposed, which is capable of combating the temporal channel quality variation of fading channels. A procedure is suggested for determining the AQAM switching thresholds and the specific turbo-coding rates capable of maintaining the target bit-error rate while aiming for achieving a highly effective bits per symbol throughput. As a design alternative, we also employ multiple-input/multiple-output DFE-aided space-time trellis codes, which benefit from transmit diversity and hence reduce the temporal channel quality fluctuations. The performance of both systems is characterized and compared when communicating over the COST 207 typical urban wideband fading channel. It was found that the turbo-coded AQAM scheme outperforms the two-transmitter space-time trellis coded system employing two receivers; although, its performance is inferior to the space-time trellis coded arrangement employing three receivers.

The decision feedback equaliser (DFE) aided turbo coded wideband adaptive quadrature amplitude modulation (AQAM) is capable of accommodating the temporal channel quality variation of fading channels. By contrast, the family of multiple-input-multiple-output (MIMO) DFE aided space-time trellis codes benefits from transmit diversity and hence it is capable reducing, rather than accommodating the temporal channel quality fluctuations. The performance of both systems is characterised and compared when communicating over the COST 207 typical urban (TU) wideband fading channel. It was found that the turbo coded AQAM scheme outperforms the two-transmitter space-time trellis coded (STTC) system employing two receivers, although its performance becomes inferior to that of a STTC arrangement employing more than two receivers.

We propose a novel space-time coding-assisted double-spread RAKE receiver (STC-DS-RR) based CDMA scheme for downlink (base to mobile) transmissions over dispersive Rayleigh fading channels. The STC-DS-RR scheme invokes turbo convolutional (TC) channel coding and space-time block coding (STBC) for achieving both time and space diversity gains in addition to the path diversity gain provided by the dispersive Rayleigh fading environments. The double-spreading mechanism of the STC-DS-RR scheme is capable of detecting the wanted user's channel-impaired wideband signals with the aid of a low-complexity RAKE receiver, without resorting to complex multi-user detection. The performance of the proposed scheme was investigated using quadrature-phase-shift-keying (QPSK), when communicating over dispersive channels. It was shown that the wideband scheme advocated is capable of achieving E/sub b//N/sub 0/ gains up to 35 dB in comparison to an uncoded narrowband single-transmitter scheme.

A reduced complexity turbo equalizer, TEQ-IQ, which uses the in-phase/quadrature-phase cancellation technique developed for single-transmitter and single-receiver systems, is proposed for space-time trellis coded (STTC) systems. The TEQ-IQ scheme is capable of approximating the performance of the conventional turbo equalizer (TEQ-CT), while achieving complexity reduction factors of 1.4 and 468.2 for a 4PSK 32-state STTC system communicating over two-path and five-path symbol-spaced and equal tap weight Rayleigh fading channels, respectively.

Following a brief historical perspective on channel coding, an introduction to space–time block codes is given. The various space–time codes considered are then concatenated with a range of channel codecs, such as convolutional and block-based turbo codes as well as conventional and turbo trellis codes. The associated estimated complexity issues and memory requirements are also considered. These discussions are followed by a performance study of various space–time and channel-coded transceivers. Our aim is first to identify a space–time code/channel code combination constituting a good engineering tradeoff in terms of its effective throughput, bit-error-rate performance, and estimated complexity. Specifically, the issue of bit-to-symbol mapping is addressed in the context of convolutional codes (CCs) and convolutional coding as well as Bose–Chaudhuri–Hocquenghem coding-based turbo codes in conjunction with an attractive unity-rate space–time code and multilevel modulation is detailed. It is concluded that over the nondispersive or narrow-band fading channels, the best performance versus complexity tradeoff is constituted by Alamouti’s twin-antenna block space–time code concatenated with turbo convolutional codes. Further comparisons with space–time trellis codes result in similar conclusions. Keywords—Channel coding, concatenated coding, FEC, history of channel coding, space–time coding, STBC, STTC.

Following a brief historical perspective on channel coding, an introduction to space-time block codes is given. The various space-time codes considered are then concatenated with a range of channel codecs, such as convolutional and block-based turbo codes as well as conventional and turbo trellis codes. The associated estimated complexity issues and memory requirements are also considered. These discussions are followed by a performance study of various space-time and channel-coded transceivers. Our aim is first to identify a space-time code/channel code combination constituting a good engineering tradeoff in terms of its effective throughput, bit-error-rate performance, and estimated complexity. Specifically, the issue of bit-to-symbol mapping is addressed in the context of convolutional codes (CCs) and convolutional coding as well as Bose-Chaudhuri-Hocquenghem coding-based turbo codes in conjunction with an attractive unity-rate space-time code and multilevel modulation is detailed. It is concluded that over the nondispersive or narrow-band fading channels, the best performance versus complexity tradeoff is constituted by Alamouti's twin-antenna block space-time code concatenated with turbo convolutional codes. Further comparisons with space-time trellis codes result in similar conclusions.

Turbo equalizers have been shown to be successful in mitigating the effects of inter-symbol interference introduced by partial response modems and by dispersive channels for code rates of R/spl les/ 1/2. We comparatively studied the performance of a range of binary phase-shift keying turbo equalizers employing block-turbo codes, namely Bose-Chaudhuri-Hocquenghen (1960, 1959) turbo codes, convolutional codes, and convolutional turbo codes having high code rates, such as R=3/4 and R=5/6, over a dispersive five-path Gaussian channel and an equally weighted symbol-spaced five-path Rayleigh fading channel. These turbo equalization schemes were combined with an iterative channel estimation scheme in order to characterize a realistic scenario. The simulation results demonstrated that the turbo-equalized system using convolutional turbo codes was the most robust system for all code rates investigated.

Space-time block codes provide substantial diversity advantages for multiple transmit antenna systems at a low decoding complexity. We investigate the achievable diversity advantages in the context of adaptive modulation aided turbo coded OFDM. The two-transmitter, one-receiver G/sub 2/ block space-time coded scheme using no channel coding or gradually increasing rate turbo coding strikes the best trade-off in terms of its overall performance and complexity. Adaptive OFDM performs impressively, when the extra complexity of space-time coding is not affordable, but no adaptive modulation is necessary in conjunction with the more complex multiple transmit and receive antenna associated scenario.

An MPEG-4 based space-time (ST) coded orthogonal frequency division multiplexing (OFDM) audio transceiver is proposed. The high-quality MPEG-4 audio codec is operated at bit rates between 16 and 64 kbit/s per channel and combined with turbo channel codes as well as space-time codes. As expected, the space-time coding scheme, using two transmitters and one receiver, outperformed the conventional one transmitter, one receiver arrangement by about 4 dB in channel SNR terms, when maintaining an error-free audio quality.

A burst-by-burst adaptive speech transceiver is proposed, which can drop its source coding rate and speech quality under transceiver control in order to invoke a more error resilient modem mode amongst less favourable channel conditions. The novel, high-quality, adaptive multi-rate (AMR) speech codec (see GSM 06.90, version 7.0.0, 1998), operated at bit rates of 4.75 and 10.2 kbps and combined with source-sensitivity-matched redundant residue number systems (RRNS) based channel codes. Burst-by-burst adaptive joint-detection based code division multiple access (JD-CDMA) is used for transmitting the dual-rate bitstream generated by the AMR speech codec.

The performance of the proposed radial basis function (RBF) assisted turbo-coded adaptive modulation scheme is characterized in a wideband channel scenario. We commence by introducing the novel concept of the Jacobian RBF equalizer, which is a reduced-complexity version of the conventional RBF equalizer. Specifically, the Jacobian logarithmic RBF equalizer generates its output in the logarithmic domain and hence it can be used to provide soft outputs for the turbo-channel decoder. We propose using the average magnitude of the log-likelihood ratio (LLR) of the bits in the received transmission burst before channel decoding as the channel quality measure for controlling the mode-switching regime of our adaptive scheme.

Space-time block codes provide substantial diversity advantages for multiple transmit antenna systems at a low decoding complexity. We concatenate space-time codes with convolutional codes (CC), turbo convolutional codes (TC), turbo BCH codes (TBCH), trellis coded modulation (TCM) and turbo trellis coded modulation (TTCM) schemes for achieving a high coding gain. The associated performance and complexity of the the coding schemes is compared.

Space-time block codes provide substantial diversity advantages in multiple transmit antenna assisted systems at a low decoding complexity. In this contribution, we concatenate space-time codes with three turbo coding schemes, namely turbo BCH (TBCH) codes, turbo convolutional (TC) codes and turbo trellis coded modulation (TTCM) schemes for the sake of achieving significant coding gain. The issues of mapping coded bits of the TBCH and TC schemes to different protection classes of various multilevel modulation schemes is also addressed. Finally, the performance and associated complexity of the three turbo schemes is compared.

The novel class of nonbinary maximum minimum distance redundant residue number system (RRNS) codes is invoked in the context of adaptively RRNS coded, symbol-by-symbol adaptive multicarrier modulation, in order to combat the effects of frequency-selective fading inflicted by dispersive wide-band channels. The system's performance can be adjusted in order to maintain a given target bit error rate (BER) and bit per symbol (BPS) performance. The proposed adaptive RRNS scheme outperforms the convolutional constituent code based turbo coded benchmarker system for channel signal-to-noise ratios (SNR) in excess of about 15 dB at a target BER of 10/sup -4/.