International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / This paper discusses an error-correcting scheme applied to a telemetry system over HF radio channel. According to the statistical properties of transmission error on HF radio channel, the scheme uses one important diffuse convolutional code, which is threshold decoded and corrects the random or burst errors. The operation of this code is explained, and a new method for word synchronization and bit synchronization is proposed. Coding and decoding, word synchronization, and bit synchronization are all activated by software program so as to greatly improve the flexibleness and applicability of the data transmission system. Test results of error-correcting are given for a variety of bit-error-rate (BER)s on HF radio channel.

Parallel concatenated convolutional codes (PCCCs), called "turbo codes" by their discoverers, have been shown to perform close to the Shannon bound at bit error rates (BERs) between 1e-4 and 1e-6. Serial concatenated convolutional codes (SCCCs), which perform better than PCCCs at BERs lower than 1e-6, were developed borrowing the same principles as PCCCs, including code concatenation, pseudorandom interleaving and iterative decoding. The first part of this dissertation introduces the fundamentals of concatenated convolutional codes. The theoretical and simulated BER performance of PCCC and SCCC are discussed. Encoding and decoding structures are explained, with emphasis on the Log-MAP decoding algorithm and the general soft-input soft-output (SISO) decoding module. Sliding window techniques, which can be employed to reduce memory requirements, are also briefly discussed. The second part of this dissertation presents four major contributions to the field of concatenated convolutional coding developed through this research. First, the effects of quantization and fixed point arithmetic on the decoding performance are studied. Analytic bounds and modular renormalization techniques are developed to improve the efficiency of SISO module implementation without compromising the performance. Second, a new stopping criterion, SDR, is discovered. It is found to perform well with lowest cost when evaluating its complexity and performance in comparison with existing criteria. Third, a new type-II code combining automatic repeat request (ARQ) technique is introduced which makes use of the related PCCC and SCCC. Fourth, a new code-assisted synchronization technique is presented, which uses a list approach to leverage the simplicity of the correlation technique and the soft information of the decoder. In particular, the variant that uses SDR criterion achieves superb performance with low complexity. Finally, the third part of this dissertation discusses the FPGA-based implementation of the turbo decoder, which is the fruit of cooperation with fellow researchers. / Ph. D.

In wireless communication system, convolutional coding method is often used to encode the data. In decoding convolutional code (CC), Viterbi algorithm is considered to be the best mechanism. Viterbi decoder (VD) was developed to execute the algorithm on mobile devices more effectively. This decoder is often used on 2G and 3G mobile phones. However, on 2G phones, VD consumes about one third of total power consumption of the signal receiver. Therefore it is very necessary to reduce the power consumption of VD on 2G and 3G phones. VD uses large amount of register in survivor metric unit (SMU), so that the decoder can receive enough CC and converge automatically. The goal of this thesis is to decrease power consumption of SMU by using path metric compare unit (PMCU) to find the best state of path metric unit (PMU). This way decreases half of registers and multiplexers required in SMU, leading to significant area reduction in decoder. During the process of signal transmission in wireless communication, different causes like the atmosphere, outer space radiation and man-made will interfere the signal by different degree. The stronger the noise is, the more interference CC will get. The error detection circuit used will mark the sections with noise interference before the CC enters the VD. If CC is interfered, it will be decoded by the whole VD. Otherwise, it will be decoded by low power decoder, where the controller will start clock gating mechanism on SMU to close up unnecessary power consumption block. The power consumption of is varying proposed Adaptive Viterbi decoder according to the interference degree. When interference degree is high, the power consumption is 21% less than conventional VD; when interference is low, it is 44% less. The results show that the proposed method can effectively reduce the power consumption of VD.

In this thesis, we consider decentralized multiclass classification problem in wireless sensor networks. In literature, the decentralized detection using error correcting code has been shown to have good fault-tolerance capability. In this thesis, we provide fault-tolerance capability by employing the code with a particular structure so that the decoding at the fusion center can be efficient. Specifically, the convolution code is employed to decode the local decision vector sent from all the local sensors. In addition, we proposed an efficient convolution code design algorithm by using simulated annealing. The simulation result shows that the proposed approach has good performance.

No description available.

Les modulations à phase continue (CPMs) sont des méthodes de modulations robuste à la noncohérence du canal de propagation. Dans un contexte spatial, les CPM sont utilisées dans la chaîne de transmission de télémesure de la fusée. Depuis les années 70, la modulation la plus usitée dans les systèmes de télémesures est la modulation CPFSK continuous phase frequency shift keying filtrée. Historiquement, ce type de modulation est concaténée avec un code ReedSolomon (RS) afin d'améliorer le processus de décodage. Côté récepteur, les séquences CPM non-cohérentes sont démodulées par un détecteur Viterbi à sortie dure et un décodeur RS. Néanmoins, le gain du code RS n'est pas aussi satisfaisant que des techniques de codage moderne capables d'atteindre la limite de Shannon. Actualiser la chaîne de communication avec des codes atteignant la limite de Shannon tels que les codes en graphe creux, implique deremanier l’architecture du récepteur usuel pour un détecteur à sortie souple. Ainsi, on propose dans cette étude d' élaborer un détecteur treillis à sortie souple pour démoduler les séquences CPM non-cohérentes. Dans un deuxième temps, on concevra des schémas de pré-codages améliorant le comportement asymptotique du récepteur non-cohérent et dans une dernière étape on élabora des codes de parité à faible densité (LDPC) approchant la limite de Shannon. / Continuous phase modulations (CPM) are modulation methods robust to the non-coherency of propagation channels. In a space context, CPMs are used in the communication link between the rocket and the base stations. Since the 70's, the most popular telemetry modulation is the filtered continuous phase frequency shift keying (CPFSK). Traditionally, the CPFSK scheme isconcatenated with a Reed-Solomon (RS) code to enhance the decoding process. At the receiver side, the non-coherent CPM sequences are demodulated through a hard Viterbi detector and a RS decoder. However, the RS's coding gain is no more satisfactory when directly compared to modern coding schemes enable to reach the Shannon limit. Updating the communication link to capacity achieving codes, as sparse graph codes, implies to redesign the receiver architecture to soft detector. In that respect, we propose in this study to design a trellis-based soft detector to demodulate non-coherent CPM sequences. In a second part, we will elaborate precoding schemes to improve the asymptotic behaviour of the non-coherent receiver and in a last step we will build low density parity check codes approaching the Shannon limit.

The continuous phase frequency shift keying (CPFSK) is a modulation method with memory. The memory results from the phase continuity of the transmitted carrier phase from one signal interval to the next. For a specific form of phase, CPFSK becomes a special case of a general class of continuous phase modulation (CPM) signals. In this thesis, we extend the decomposition model of single-h CPM to the multi-h CPM decomposition model. Based on this decomposition model approach the multi-h CPFSK schemes are evaluated by searching the desired multi-h phase codes at a given number of states. Moreover, the trellis coded multi-h CPFSK schemes, which are the combination of the (binary) convolutional codes with the multi-h CPFSK schemes, are searching by optimization procedure via the matched encoding method. To further improve the performance, in terms of the coding gain, the ring convolutional codes are applied to the continuous phase encoder (CPE) of the proposed multi-h CPFSK schemes. Due to the fact that the code structure of the ring convolutional codes is similar to the CPE, this will result in having simple and efficient combination of the convolutional codes with the multi-h CPFSK signaling schemes.

No description available.

No / Abstract: Error control techniques are designed to ensure reliable data transfer over unreliable communication channels that are frequently subjected to channel errors. In this paper, the effect of applying a convolution code to the Scattered Random Network Coding (SRNC) scheme over a multi-hop wireless channel was studied. An interleaver was implemented for bit scattering in the SRNC with the purpose of dividing the encoded data into protected blocks and vulnerable blocks to achieve error diversity in one modulation symbol while randomising errored bits in both blocks. By combining the interleaver with the convolution encoder, the network decoder in the receiver would have enough number of correctly received network coded blocks to perform the decoding process efficiently. Extensive simulations were carried out to study the performance of three systems: 1) SRNC with convolutional encoding, 2) SRNC; and 3) A system without convolutional encoding nor interleaving. Simulation results in terms of block error rate for a 2-hop wireless transmission scenario over an Additive White Gaussian Noise (AWGN) channel were presented. Results showed that the system with interleaving and convolutional code achieved better performance with coding gain of at least 1.29 dB and 2.08 dB on average when the block error rate is 0.01 when compared with system II and system III respectively.

In this thesis, fast Viterbi Decoder algorithms for a multi-core system are studied. New parallel Viterbi algorithms for decoding convolutional codes are proposed based on tail biting trellises. The performances of the new algorithms are first evaluated by MATLAB and then Eagle (E-UTRA algorithms for LTE) link level simulations where the optimal parameter settings are obtained based on various simulations. One of the algorithms is proposed for implementation in the product due to its good BLER performance and low implementation complexity. The new parallel algorithm is then implemented on target DSPs for Ericsson internal multi-core system to decode the PUSCH (Physical Uplink Shared Channel) CQI (Channel Quality Indicator) in LTE (Long Term Evolution). And the performance of the new algorithm in the real multi-core system is compared against the current implementation regarding both cycle and memory consumption. As a fast decoder, the proposed parallel Viterbi decoder is computationally efficient which reduces significantly the decoding latency and solves memory limitation problems on DSP.