Asynchronous MAC Protocol for Spectrum Agility in Wireless Body Area Sensor Networks

International audienceA Wireless Body Area Sensor Network (WBASN) is a special-purpose Wireless Sensor Network (WSN) that supports remote monitoring and entertainment applications. The energy consumption plays an important role in the design of this specific sensor network. Unfortunately, the performance of WBASNs decreases in high interference environments such as the Industrial, Scientific and Medical (ISM) band where wireless spectrums are getting crowded. In this paper, an energy-efficient Medium Access Control (MAC) protocol named C-RICER (Cognitive-Receiver Initiated CyclEd Receiver) is specifically designed for WBASN to cognitively work in high interference environment. C-RICER protocol adapts both transmission power and channel frequency to reduce the interferences and thus, the energy consumption. The protocol is simulated thanks to OMNET++ simulator. Simulation results show that, depending on the interference level, C-RICER is able to outperform the traditional RICER protocol in terms of energy consumption, packet delay, and network throughput

Optimisation de précodeurs linéaires pour les systèmes MIMO à récepteurs itératifs

The long-term evolution (LTE) and the LTE-Advanced (LTE-A) standardizations are predicted to play essential roles in the future fifth-generation (5G) mobile networks. These standardizations require high data rate and high quality of service, which assures low error-rate and low latency. Besides, as discussed in the recent surveys, low complexity communication systems are also essential in the next 5G mobile networks. To adapt to the modern trend of technology, in this PhD thesis, we investigate the multiple-input multiple-output (MIMO) wireless communication schemes. In the first part of this thesis, low-complex forward error correction (FEC) codes are used for low complexity and latency. By considering iterative receivers at the receiver side, we exploit MIMO linear precoding and mapping methods to optimize the error-rate performance of these systems. In the second part of this thesis, non-binary low density parity check (NB-LDPC) codes are investigated. We propose to use MIMO precoders to reduce the complexity for NB-LDPC encoded MIMO systems. A novel low complexity decoding algorithm for NB-LDPC codes is also proposed at the end of this thesis.Les standards « Long-term evolution » (LTE) et LTE-Advanced (LTE-A) devraient influencer fortement l’avenir de la cinquième génération (5G) des réseaux mobiles. Ces normes exigent de hauts débits de données et une qualité de service de très bon niveau, ce qui permet d’assurer un faible taux d’erreur, avec une faible latence. Par ailleurs, la complexité doit être limitée. Dans le but de déterminer des solutions technologiques modernes qui satisfont ces contraintes fortes, nous étudions dans la thèse des systèmes de communication sans fil MIMO codés. D’abord, nous imposons un simple code convolutif récursif systématique (RSC) pour limiter la complexité et la latence. En considérant des récepteurs itératifs, nous optimisons alors la performance en termes de taux d’erreur de ces systèmes en définissant un précodage linéaire MIMO et des techniques de mapping appropriées. Dans la deuxième partie de la thèse, nous remplaçons le RSC par un LDPC non-binaire (NB-LDPC). Nous proposons d’utiliser les techniques de précodage MIMO afin de réduire la complexité des récepteurs des systèmes MIMO intégrant des codes NB-LDPC. Enfin, nous proposons également un nouvel algorithme de décodage itératif à faible complexité adapté aux codes NB-LDPC

Optimization of linear precoders for coded MIMO systems with iterative receivers

Les standards « Long-term evolution » (LTE) et LTE-Advanced (LTE-A) devraient influencer fortement l’avenir de la cinquième génération (5G) des réseaux mobiles. Ces normes exigent de hauts débits de données et une qualité de service de très bon niveau, ce qui permet d’assurer un faible taux d’erreur, avec une faible latence. Par ailleurs, la complexité doit être limitée. Dans le but de déterminer des solutions technologiques modernes qui satisfont ces contraintes fortes, nous étudions dans la thèse des systèmes de communication sans fil MIMO codés. D’abord, nous imposons un simple code convolutif récursif systématique (RSC) pour limiter la complexité et la latence. En considérant des récepteurs itératifs, nous optimisons alors la performance en termes de taux d’erreur de ces systèmes en définissant un précodage linéaire MIMO et des techniques de mapping appropriées. Dans la deuxième partie de la thèse, nous remplaçons le RSC par un LDPC non-binaire (NB-LDPC). Nous proposons d’utiliser les techniques de précodage MIMO afin de réduire la complexité des récepteurs des systèmes MIMO intégrant des codes NB-LDPC. Enfin, nous proposons également un nouvel algorithme de décodage itératif à faible complexité adapté aux codes NB-LDPC.The long-term evolution (LTE) and the LTE-Advanced (LTE-A) standardizations are predicted to play essential roles in the future fifth-generation (5G) mobile networks. These standardizations require high data rate and high quality of service, which assures low error-rate and low latency. Besides, as discussed in the recent surveys, low complexity communication systems are also essential in the next 5G mobile networks. To adapt to the modern trend of technology, in this PhD thesis, we investigate the multiple-input multiple-output (MIMO) wireless communication schemes. In the first part of this thesis, low-complex forward error correction (FEC) codes are used for low complexity and latency. By considering iterative receivers at the receiver side, we exploit MIMO linear precoding and mapping methods to optimize the error-rate performance of these systems. In the second part of this thesis, non-binary low density parity check (NB-LDPC) codes are investigated. We propose to use MIMO precoders to reduce the complexity for NB-LDPC encoded MIMO systems. A novel low complexity decoding algorithm for NB-LDPC codes is also proposed at the end of this thesis

Asynchronous MAC Protocol for Spectrum Agility in Wireless Body Area Sensor Networks

International audienceA Wireless Body Area Sensor Network (WBASN) is a special-purpose Wireless Sensor Network (WSN) that supports remote monitoring and entertainment applications. The energy consumption plays an important role in the design of this specific sensor network. Unfortunately, the performance of WBASNs decreases in high interference environments such as the Industrial, Scientific and Medical (ISM) band where wireless spectrums are getting crowded. In this paper, an energy-efficient Medium Access Control (MAC) protocol named C-RICER (Cognitive-Receiver Initiated CyclEd Receiver) is specifically designed for WBASN to cognitively work in high interference environment. C-RICER protocol adapts both transmission power and channel frequency to reduce the interferences and thus, the energy consumption. The protocol is simulated thanks to OMNET++ simulator. Simulation results show that, depending on the interference level, C-RICER is able to outperform the traditional RICER protocol in terms of energy consumption, packet delay, and network throughput

Optimization of linear MIMO precoding assuming MMSE-based turbo equalization

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Association and Joint Optimization of max-dmin Precoder with MIMO Turbo Equalization

International audienceIn this paper, we investigate the concatenation of the multiple input multiple output (MIMO) max-dmin linear precoder with an outer forward error correction (FEC) code at the transmitter. At the receiver side, the turbo equalization is taken into account, which iteratively exchanges the extrinsic information between a minimum mean square error interference canceller (MMSE IC) and a FEC decoder. The analysis done by extrinsic information transfer (EXIT) chart shows that a higher mutual information (MI) at the convergence state of the turbo equalization is observed thanks to the linear precoder. In addition, we exploit this property to propose a new precoder named max-dmin-mod. Numerical simulations are in accordance with the theoretical analysis, which exhibits a significant improvement of the error-rate of the turbo equalization as well as a significant gain of max-dmin-mod compared to original max-dmin precoder

EXIT-based optimization of linear precoder for MIMO encoded systems assuming turbo detection

International audienceThe concatenation of the multiple-input multiple- output (MIMO) linear precoder with an outer forward error correction (FEC) code at the transmitter is investigated in this pa- per. At the receiver side, the turbo detection is taken into account, which iteratively exchanges the extrinsic information between a soft-demapper and a FEC soft-decoder. We firstly propose a new precoder named F_I_1 precoder thanks to the extrinsic information transfer (EXIT) chart analysis. The proposed precoder aims to optimize the iterative receiver convergence by maximizing the ending point I_1 of the soft-demapper EXIT function. For the sake of low-complexity, F_I_1 is designed for two data streams MIMO transmission only. Secondly, to cope with the higher data streams transmission, a global b = 2K data streams system is split into K two data streams subsystems. F_I_1 is then applied at each subsystem. Finally, we propose a new algorithm to optimize the inter-subsystems power allocation with the criterion is to maximize I_1 of the global system

Optimized max-dmin precoder assuming maximum squared Euclidean weight-mapping and turbo detection

International audienceThe concatenation of multiple-input multiple-output (MIMO) linear precoder with an outer forward error correction (FEC) encoder is investigated at the transmitter. Turbo detection is applied at the receiver for the decoding. The bit-interleaved codeword is considered to be grouped and mapped directly onto the received constellation thanks to a MIMO symbol mapper. We exploit the optimal maximum squared Euclidean weight (MSEW) mappings for two forms of max-dmin precoder to propose a novel precoder referred to as max-lmin. The switching threshold between both forms is optimized by considering all received sequences whose binary mappings differ by exactly one bit and by first maximizing the minimum Euclidean distance within this set and then minimizing the number of pairs achieving it. Extrinsic information transfer (EXIT) chart is also used to validate the analysis. Simulation results show significant improvement, in terms of system error-rate performance, of the max-lmin compared to the conventional max-dmin

Optimized MIMO symbol mapping to improve the turbo cliff region of iterative precoded MIMO detection

International audienceIn this paper we investigate the concatenation of the multi- ple input multiple output (MIMO) max-dmin linear precoder with an outer forward error correction code (FEC) code as- suming turbo detection at the receiver. A maximum squared Euclidean weight (MSEW) binary-to-MIMO symbol mapper is introduced in the precoding scheme. Extrinsic information transfer (EXIT) chart is used to analyze the turbo-cliff and error-floor of the proposed MIMO symbol mapper. Analysis and simulation results show significant improvement of the symbol mapper in terms of error-rate performance

Precoded MIMO Systems with Nonbinary LDPC Codes and Many-to-One Mapping

A precoding design is proposed for multiple-input multiple-output (MIMO) systems utilizing nonbinary low-density parity check (NB-LDPC) codes and many-to-one mapping. When a high-order modulation scheme is used, many-to-one mapping converts a group of low-order Galois field (GF) coded symbols into one modulated MIMO symbol vector. In contrast, one-to-one mapping maps a high-order modulation symbol directly from one high-order GF coded symbol. With the help of an interleaver between the NB-LDPC encoder and the GF to MIMO symbol mapper, the many-to-one mapping enables turbo receiver and reduces the computational complexity by more than 95%. The proposed MIMO precoders enhance the error-rate performance of the many-to-one NB-LDPC MIMO system, especially in terms of reducing the error floor and improving the waterfall region. The proposed precoder design modifies the approach that suboptimally maximizes the minimal Euclidean distance between the received MIMO symbols. Simulation results show that the proposed precoders enhance the robustness of the precoder design and reduce the inner and outer iterations of the turbo receiver