This Diploma thesis aims to explain the data coding using turbo codes. These codes belong to the group of error correction codes. We can reach the high efficiency using these codes. The first part describes process of encoding and decoding. There are describes parts of encoder and decoder. Principle of encoding and decoding demonstrate a simple example. The end of this part contains description of two most frequently used decoding algorithms (SOVA and MAP). The second part contains description of computer program that was made for using as teaching aid. This program was created in Matlab GUI. This program enables to browse error correction process step by step. This program contains graphic interface with many options and display results. In the third part is described program created in Matlab Simulink that was implemented into the TMS320C6713 kit and there is description of measuring procedure. For verification of efficiency of turbo codes was measured any parameters. Some of these parameters are: number of decoding iterations, generating polynoms and using of puncturing. The last part contains measured value and result evaluation.

L’objectif de cette thèse est l’étude de récepteurs MIMO LDPC itératifs. Les techniques MIMO permettent d’augmenter la capacité des réseaux sans fil sans la nécessité de ressources fréquentielles additives. Associées aux schémas de modulations multiporteuses CP-OFDM, les techniques MIMO sont ainsi devenues la pierre angulaire pour les systèmes sans fil à haute efficacité spectrale. La réception optimale peut être obtenue à l’aide d’une réception conjointe (Egalisation/Décodage). Étant très complexe, la réception conjointe n’est pas envisagée et l’égalisation et le décodage sont réalisés disjointement au coût d’une dégradation significative en performances. Entre ces deux solutions, la réception itérative trouve son intérêt pour sa capacité à s’approcher des performances optimales avec une complexité réduite. La conception de récepteurs itératifs pour certaines applications, de type WiFi à titre d’exemple doit respecter la structure du code imposée par la norme. Ces codes ne sont pas optimisés pour des récepteurs itératifs. En observant l’effet du nombre d' itérations dans le processus itératif, on montre par simulation que l’ordonnancement des itérations décodage LDPC/Turbo-égalisation joue un rôle important dans la complexité et le délai du récepteur. Nous proposons de définir des ordonnancements permettant de réduire la complexité globale du récepteur. Deux approches sont proposées, une approche statique ainsi qu'une autre dynamique. Ensuite nous considérons un système multi-utilisateur avec un accès multiple par répartition spatiale. Nous étudions l’intérêt de la réception itérative dans ce contexte tenant en compte la différence de puissance signale utile/interférence. / The aim of this thesis is to address the design of iterative MIMO receivers using LDPC Error Correcting codes. MIMO techniques enable capacity increase in wireless networks with no additional frequency ressources. The associationof MIMO with multicarrier modulation techniques OFDM made them the cornerstone of emerging high rate wireless networks. Optimal reception can be achieved using joint detection and decoding at the expense of a huge complexity making it impractical. Disjoint reception is then the most used. The design of iterative receivers for some applications using LDPC codes like Wifi (IEEE 802.11n) is constrained by the standard code structure which is not optimized for such kind of receivers. By observing the effect of the number of iterations on performance and complexity we underline the interest of scheduling LDPC decoding iterations and turboequalization iterations. We propose to define schedules for the iterative receiver in order to reduce its complexity while preserving its performance. Two approaches are used : static and dynamic scheduling. The second part of this work is concerns Multiuser MIMO using Spatial Division Multiple Access. We explore and evaluate the interest of using iterative reception to cancel residual inter-user interference.

Detta examensarbete har gått ut på att undersöka möjligheten till implementerande av ett trådlöst mätsystem för en turboladdare samt sedan ta fram en basinstallation för det valda systemet. Genom att tillämpa användningen av ett trådlöst mätsystem till Scanias turboaggregat så kan mätvärdena som erhålls användas till fortsatta designförbättringar och verka som en kontroll av Scanias turboleverantörer. Arbetet har behandlat studier i olika trådlösa mätsystem och sedan utse det som passar Scanias turboaggregat bäst, detta blev då telemetrisystemet. Arbetet fortsatte med etablering av kontakt med leverantörer och senare matcha Scanias krav och begränsningar med leverantörens föreslagna system. Arbetet har också hanterat framtagandet utav CADmodeller, ritningar för en monteringslösning till telemetrisystemet. Detta betydde att konstruera inom turboaggregatets begränsningar och driftområden så att monteringslösningen kan hantera de hårda förhållanden systemet kommer utsättas för vid drift. Arbetet resulterade med en framtagen offert och en systembeställning av ett 2 kanalsystem, även framtogs två stycken olika monteringslösningar som kan användas för fästa av telemetrisystemet i turboaggregatet. / The aim of this thesis has been to investigate the feasibility of a wireless measurement system for a HD turbocharger, and then implementing a base installation for the selected system. By applying the usage of a wireless measurement system to one of Scania’s turbochargers, the measurement values that obtained can be used for design improvements and as a verifier of Scania’s turbo suppliers. The thesis has covered studies in different wireless measurement system and later choosing one that fits Scania’s turbochargers best, this became the telemetry system. The thesis has also covered the development of CAD-models and drawings for a mounting solution to the telemetry system. This meant designing within the turbochargers design limits and operating areas so that the mounting solution could deal with the harsh condition the system will be exposed to. The thesis resulted in ordering the 2 channel telemetry system and a development of two different mounting solution that can be used to fasten the telemetry system within the turbocharger.

No description available.

Le traitement itératif est actuellement largement répandu dans les récepteurs sans fil modernes pour le décodage des codes de canal avancés. L'extension de ce principe avec l'ajout d'une boucle de rétroaction vers l'égaliseur et le demappeur a montré d'excellentes performances dans des conditions sévères de canaux de transmission (effacement, multi-trajets, modèles réels de canaux à évanouissements). Toutefois, l'adoption du traitement itératif avec du turbo décodage est fortement limitée par la complexité d'implémentation engendrée, qui impacte fortement sur le débit, la latence et la consommation. Pour faire face à ces problèmes et permettre l'adoption généralisée du traitement itératif, de nouvelles techniques d'optimisation au niveau système doivent être exploitées. Dans ce travail, nous avons étudié la vitesse de convergence et la complexité au niveau système des récepteurs avancés combinant plusieurs processus itératifs. La première partie de cette thèse a été axée sur l'étude de la combinaison de la démodulation itérative avec du turbo décodage, tandis que la deuxième partie a étendu cette étude vers les récepteurs itératifs MIMO en appliquant de la turbo égalisation, de la turbo démodulation et du turbo décodage. Plusieurs techniques de communication et paramètres système, tels que spécifiés dans les applications émergentes de communication sans fil, ont été pris en compte. De nouveaux ordonnancements des itérations pour les boucles de rétroaction internes et externes ont été proposés pour améliorer la convergence et réduire la complexité globale en termes d'opérations arithmétiques et d'accès mémoire. En outre, l'analyse effectuée et les ordonnancements proposés démontrent l'efficacité des boucles de rétroaction externes, même en termes de complexité, par rapport aux récepteurs classiques non itératifs. Ces résultats ont permis la proposition de nouveaux récepteurs itératifs à complexité adaptative appliquant du turbo décodage, de la turbo démodulation et de la turbo égalisation.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper considers the use of Amplitude-Phase Shift Keying (APSK) for a telemetry system. Variable rate turbo codes are used to improve the power efficiency of 16- and 32-APSK. We discuss compensation techniques for power amplifier nonlinearities. Simulation results show the improved spectral efficiency of this modulation scheme over those currently defined in telemetry standards.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / It has been shown that a multi-symbol detector can improve the detection efficiency of PCM/FM by 3 dB when compared to traditional methods without any change to the transmitted waveform. Although this is a significant breakthrough, further improvements are possible with the addition of Forward Error Correction (FEC). Systematic redundancy can be added by encoding the source data prior to the modulation process, thereby allowing channel errors to be corrected using a decoding circuit. Better detection efficiency translates into additional link margin that can be used to extend the operating range, support higher data throughput, or significantly improve the quality of the received data. This paper investigates the detection efficiency that can be achieved using a multisymbol detector and turbo product coding. The results show that this combination can improve the detection performance by nearly 9 dB relative to conventional PCM/FM systems. The increase in link margin is gained at the expense of a small increase in bandwidth and the additional complexity of the encoding and decoding circuitry.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Telemetry for Earth-Observation missions is characterized by very high data rates and stringent requirements. Channel codes both power and bandwidth efficient must be used to improve downlink performance and to achieve the very low values of error rates needed at the received side. In this paper, we review and analyzed three codes of possible interest for these applications: turbo codes, serial turbo codes and product codes. These schemes are evaluated and compared both by simulation and analytical techniques. A particular attention is devoted to complexity, a key issue for practical implementation at high data rates.

The objective of this thesis is to develop tools for the analysis and optimization of an iterative receiver. These tools can be applied to most soft-in soft-out (SISO) receiver components. For illustration purposes we consider a multi-user DS-CDMA system with forward error correction that employs iterative multi-user detection based on soft interference cancellation and single user decoding. Optimized power levels combined with adaptive scheduling allows for efficient utilization of receiver resources for heavily loaded systems.¶ Metric transfer analysis has been shown to be an accurate method of predicting the convergence behavior of iterative receivers. EXtrinsic Information (EXIT), fidelity (FT) and variance (VT) transfer analysis are well-known methods, however the relationship between the different approaches has not been explored in detail. We compare the metrics numerically and analytically and derive functions to closely approximate the relationship between them. The result allows for easy translation between EXIT, FT and VT methods. Furthermore, we extend the $J$ function, which describes mutual information as a function of variance, to fidelity and symbol error variance, the Rayleigh fading channel model and a channel estimate. These $J$ functions allow the \textit{a priori} inputs to the channel estimator, interference canceller and decoder to be accurately modeled. We also derive the effective EXIT charts which can be used for the convergence analysis and performance predictions of unequal power CDMA systems.¶ The optimization of the coded DS-CDMA system is done in two parts; firstly the received power levels are optimized to minimize the power used in the terminal transmitters, then the decoder activation schedule is optimized such that the multi-user receiver complexity is minimized. The uplink received power levels are optimized for the system load using a constrained nonlinear optimization approach. EXIT charts are used to optimize the power allocation in a multi-user turbo-coded DS-CDMA system. We show through simulation that the optimized power levels allow for successful decoding of heavily loaded systems with a large reduction in the convergence SNR.¶ We utilize EXIT chart analysis and a Viterbi search algorithm to derive the optimal decoding schedule for a multi component receiver/decoder. We show through simulations that decoding delay and complexity can be significantly reduced while maintaining BER performance through optimization of the decoding schedule.

<p>Wireless communication is always struggling with errors in the transmission. The digital data received from the radio channel is often erroneous due to thermal noise and fading. The error rate can be lowered by using higher transmission power or by using an effective error correcting code. Power consumption and limits for electromagnetic radiation are two of the main problems with handheld devices today and an efficient error correcting code will lower the transmission power and therefore also the power consumption of the device. </p><p>Duo-binary CTC is an improvement of the innovative turbo codes presented in 1996 by Berrou and Glavieux and is in use in many of today's standards for radio communication i.e. IEEE 802.16 (WiMAX) and DVB-RSC. This report describes the development of a duo-binary CTC decoder and the different problems that were encountered during the process. These problems include different design issues and algorithm choices during the design.</p><p>An implementation in VHDL has been written for Alteras Stratix II S90 FPGA and a reference-model has been made in Matlab. The model has been used to simulate bit error rates for different implementation alternatives and as bit-true reference for the hardware verification.</p><p>The final result is a duo-binary CTC decoder compatible with Alteras Stratix II designs and a reference model that can be used when simulating the decoder alone or the whole signal processing chain. Some of the features of the hardware are that block sizes, puncture rates and number of iterations are dynamically configured between each block Before synthesis it is possible to choose how many decoders that will work in parallel and how many bits the soft input will be represented in. The circuit has been run in 100 MHz in the lab and that gives a throughput around 50Mbit with four decoders working in parallel. This report describes the implementation, including its development, background and future possibilities.</p>