Performance approximation for trellis coded diversity receivers over slowly fading Rayleigh channels

Higher-order modulation schemes like 8PSK combined with powerful channel coding techniques like trellis coding and conjugateness Reed-Solomon coding, have been demonstrated in the INTELSAT study INTEL-1268 to achieve a higher bandwidth efficiency compared to QPSK with conventional coding. Almost error-free transmission (BER 5 dB with QPSK modulation, rate-3/4 convolutional code conjugateness with RS code according to IESS-308 (IDR), and for E/sub b//N/sub o/>6 dB with 8PSK modulation, rate-2/3 trellis code conjugateness with a (255,235,10) RS code. The following efficiencies are obtained: QPSK: (rate 3/4 Viterbi plus RS coding). Efficiency=1.15 bit/s/Hz and 8-PSK: (rate 2/3 trellis plus RS coding). Efficiency=1.54 bit/s/Hz. The overall transmission delay for a typical 2 Mbps carrier is: QPSK: (rate 3/4 Viterbi plus RS coding). Delay=3 ms (@ 2.048 Mbps) and 8PSK: (rate 2/3 trellis plus RS coding). Delay=10 ms (@ 2.048 Mbps). The feasibility of fully software switchable and programmable QPSK/8PSK modem/codec equipment has been demonstrated. Price estimates for this switchable QPSK/8PSK modem/codec equipment show excellent price/performance ratios for this new type of equipment.

Foschini's diagonally layered space-time transmission system known as D-BLAST is an architecture designed for a Rayleigh fading environment using multiple element antenna arrays at both the transmit and receive sites to achieve very high spectral efficiencies. In this paper, we propose a simple coding technique for D-BLAST that uses a single trellis code with finite-traceback Viterbi decoding. We examine the performance of universal trellis codes that are designed to have a distance structure that is matched to the periodic signal-to-noise ratio (SNR) variation of the channel created by D-BLAST, under the assumption that the channel is static during one burst but may change from burst to burst. We show that a universal 64-state trellis code on a 2/spl times/2 D-BLAST system with long enough block lengths displays universal behavior working on almost every 2/spl times/2 channel with at least the mutual information required by a standard 64-state AWGN trellis code. The only 2/spl times/2 channel where more mutual information is required is a certain rotation of the zero eigenvalue channel. We also present 4/spl times/4 and 8/spl times/8 examples.

An enhanced transmission is presented in a multiple‐input‐multiple‐output (MIMO) dense‐wavelength division multiplexed (DWDM) free‐space‐optical (FSO) communication link using diversity coding techniques under the effect of turbulent weather phenomenon. The findings show good performance with an (8 channels × 2.5 Gbps data rate/channel) 20 Gbps 1500 m transmission distance. The bit‐error‐rate (BER), outage probability (OP), and signal‐to‐noise ratio (SNR) of the diversity combining techniques using maximum‐ratio combining (MRC), selection combining (SC), and equal‐gain combining (EGC) technique are evaluated in this work. The obtained results illustrate that Alamouti, space‐time coding (STC), space‐time block coding (STBC), space‐time trellis code (STTC), orthogonal STBC (O‐STBC), and quasi‐orthogonal STBC ( QO‐STBC ) on the minimum mean‐square‐error, and MRC are worth implementing on the DWDM‐FSO wireless communication systems. The mitigation of atmospheric turbulence is achieved using MIMO diversity combining techniques coding. The simulation results for diversity coding techniques using QO‐STBC/STTC and SC/MRC in the MIMO‐DWDM FSO communication system can improve BER performance, OP, and SNR. The MRC exhibits the lowest OP and BER when compared with the SC and EGC. The numerical results demonstrate that the FSO communication link using DWDM QO‐STBC/STTC improves the power penalty at both BER values under varying atmospheric turbulence conditions for ST, MT, and WT, in comparison to FSO systems without DWDM QO‐STBC/STTC diversity coding techniques.

Open-loop (no feedback) pre-processing methods for improving the error-rate performance of space-time trellis codes in additive white Gaussian noise (AWGN) and Ricean channels which nearly preserve the performance in Rayleigh channels are proposed. The rotation based pre-processing preserves the Rayleigh channel performance, whereas there is a small degradation in performance in the power division based pre-processing. This degradation depends on the trellis complexity, and is more pronounced for the lower state trellis codes. In this letter, we propose a one-bit feedback method, that improves the performance of the power division method in Rayleigh channels. Simulation results for a 2/spl times/1 system show that this improvement is significant for the higher state trellis codes. The one-bit feedback is used to determine which of the two channels has a higher gain, and the higher power is assigned to the corresponding transmitter.

Turbo trellis coded modulation (TTCM) has been widely used as a channel coding scheme that achieves nearcapacity rate without sacrificing bandwidth. Traditionally, linear trellis codes are used as the constituent encoders in the design of TTCM schemes. In this paper we design nonlinear trellis codes that outperform previously designed code over AWGN and fullyinterleaved Rayleigh fading channels.

A coset of a convolutional code may be used to generate a zero-run length limited trellis code for a 1-D partial-response channel. The free squared Euclidean distance, d/sub free//sup 2/, at the channel output is lower bounded by the free Hamming distance of the convolutional code. The lower bound suggests the use of a convolutional code with maximal free Hamming distance, d/sub max/(R,N), for given rate R and number of decoder states N. In this paper we present cosets of convolutional codes that generate trellis codes with d/sub free//sup 2/>d/sub max/(R,N) for rates 1/5/spl les/R/spl les/7/9 and (d/sub free//sup 2/=d/sub max/(R,N) for R=13/16,29/32,61/64, The tabulated convolutional codes with R/spl les/7/9 were not optimized for Hamming distance. Instead, a computer search was used to determine cosets of convolutional codes that exploit the memory of the 1-D channel to increase d/sub free//sup 2/ at the channel output. The search was limited by only considering cosets with certain structural properties. The R/spl ges/13/16 codes were obtained using a new construction technique for convolutional codes with free Hamming distance 4. Newly developed bounds on the maximum zero-run lengths of cosets were used to ensure a short maximum run length at the 1-D channel output.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A combined source/channel coding and modulation technique is developed for the transmission of memoryless sources over an AWGN channel. Combined source/channel coding is implemented using the concepts of trellis coded quantization (TCQ) in conjunction with an Ungerboeck code defined for a continuous phase frequency shift keying (CPFSK) signaling scheme. The Viterbi algorithm is employed by the source encoder to find a minimum mean-square-error (MSE) path through the source code trellis. The resultant minimum distortion sequence is mapped to an appropriate set of CPFSK symbols for transmission. A mapping is pragmatically developed to simultaneously preserve the original branch labelings of both the source and channel code trellises. Source symbol recovery is performed by maximum likelihood sequence estimation. The total distortion is experimentally determined over a range of channel signal-to-noise ratios. Furthermore, it is demonstrated that the use of a CPFSK signaling scheme avoids the production of spectral line components in the transmitted waveform spectrum that are usually associated with joint source/channel coding schemes.

In this paper, error performance bounds are derived for 8-PSK trellis coded modulation (TCM) over Gaussian and fading channels in the presence of phase noise. Coherent demodulation combined with both phase-locked loop (PLL) and transparent tone in band technique (TTIB) for phase recovery is assumed. The analysis is then applied to a number of Ungerboeck 8-PSK trellis codes and the results for the bit error rate (BER) performance, obtained both analytically and by Monte Carlo simulation, are presented. The derived bounds can be directly extended to any M-PSK trellis code. >

An optimal maximal ratio combiner (MRC) based on the expectation-maximization (EM) algorithm is devel- oped for noisy constant envelope signals transmitted over a Rayleigh fading channel. Instead of using a transmitted pilot signal with the data to estimate the combiner gains, the EM algorithm is used to perform this estimation. In the developed MRC, estimation of the transmitted data sequence is performed also by the EM algorithm. Estimation using the EM algo- rithm provides an iterative solution to the maximum likelihood (ML) approach. Therefore, the resulting receiver is opti- mum and does not suffer from the difficulties resulted from direct application of the ML procedure. One of these difficul- ties is the computational complexity which depends exponentially on the data sequence length. Introducing an iterative structure in the developed MRC achieves a linear computational complexity and enables efficient data extraction by the Viterbi algorithm when trellis coding is used.

The wireless communications industry has been experiencing phenomenal annual growth rates recently. This degree of growth reflects the tremendous demand for commercial untethered communications services such as paging, analog and digital cellular telephony, and emerging Personal Communications Services (PCS). This article examines multipath fading channels and analytical tools for wireless system design. These analytical techniques are suitable as the first step of the design process of communication systems. Several such techniques are illustrated via examples on diversity reception, outage analysis and trellis codes. Theoretical expressions are derived for parameters such as the average error rate, the average output signal‐to‐noise ratio and the outage probability. Results for selection combining and maximal‐ratio combining and equal gain combining are obtained.

Fluctuating targets are important phenomenons that affect detection probability. Several investigations about this topic have been carried on with good results to radar capabilities improvement. However, the increasing development of stealth technology has weakened traditional surveillance systems. This work has as main objective to improve radar detection of fluctuating targets using error control codes techniques. The purposed novel idea consists on a long pulse divided into a number of shorter sub-pulses, equally spaced in time duration. The binary phases of these sub-pulses are selected in accordance with Barker codes. Convolutional coding and Binary Phase Shift Keying(BPSK) modulation techniques are used. We determinate the probability of detection computing the bit error rate values. Matlab software is used to make several simulations that back up this theory. The results demonstrate that the probability of detection for Swerling I and Swerling III fluctuating target models is increased with the use of convolutional coding technique to detect and correct sub-pulse errors. This work offers a preliminary analysis of the detection improvement method with the use of error-control coding on radar pulsed with quite generalized assumptions thereby left a bigger space for future work with assumptions to fit practical implementation of the method.

It is well known that trellis lossy source codes have better performance/complexity tradeoff than block codes, as shown by simulations. This makes the trellis coding technique attractive in practice. To get a better understanding of this fact, this paper studies the redundancy of trellis coding for memoryless sources and compares it with a similar result for block codes.

Suitable bandwidth efficient coding techniques, to be combined with Q2PSK signals, are derived and analysed on AWGN and nonlinear channels. Five new Q2PSK TCs are presented. First, an expanded Q2PSK signal constellation has been used to design new 4D RI Q2PSK TCs. Partition of the 4D expanded Q2PSK signal space into 2D subspaces has allowed the utilisation of any 8-PSK TC to be implemented along Q2PSK signals. This novel division of the Q2PSK signal space has been utilised to implement double 8-PSK TCs designed by Ungerboeck and double convolutional codes over ring modulo-8 along Q2PSK signals. Finally, an unexpanded Q2PSK signal has been considered to implement and design 2/4 and 3/4 rate Q2PSK trellis codes. Performance evaluation of coded and uncoded Q2PSK signals on nonlinear satellite channels is reported, and the results obtained from computer simulations of coded and uncoded Q2PSK on nonlinear channels are presented, where different amplifier working situations have been considered.

The High Performance Waveform (HPW) was developed before parallel concatenated codes (PCCC) and serial concatenated codes (SCCC) were in wide use and so it makes sense to take advantage of the advancements in communication theory and processor computation speed that have taken place since its inception. In its current form, HPW transmits a Raised-Cosine Continuous Phase Modulation (1RC CPM) modulation with a trellis code that is designed to provide, with the use of a Cyclic Redundancy Check Code error detection (CRC), error free transmission over a single, narrowband UHF satellite communications channel. In this paper we present an additional set of coding and modulation schemes which take advantage of serial concatenated code (SCCC) technology to simultaneously improve throughput at the lower end of the signal-to-noise ratio (SNR) range while increasing the highest throughput at the highest SNR available on UHF satellites. The overall bit error rate and throughput of each individual modulation type is analyzed and the framework for the adaptive modulation protocol is provided. To provide for a gradual release of a newer revision of HPW, a framework for a PHY layer is provided which will allow a heterogeneous network of legacy and updated radio terminals.

A direct-sequence spread-spectrum communication system which uses a form of trellis coding is considered. The authors analyze the performance of this system for a channel model which includes the effects of multiple-access interference, Gaussian noise and Rician fading. Upper and lower bounds on the probability of occurrence of dominant error events are obtained by modeling the continuous probability density functions of noise and interference as discrete probability mass functions. Bit error rates are reported for coded and uncoded systems with equivalent power, bandwidth and transmission rates. It is found that while coded systems without interleaving yield only modest performance improvements over uncoded systems, coded systems with interleaving perform dramatically better. >