19 research outputs found
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 systÚmes 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 lâavenir de la cinquiĂšme gĂ©nĂ©ration (5G) des rĂ©seaux mobiles. Ces normes exigent de hauts dĂ©bits de donnĂ©es et une qualitĂ© de service de trĂšs bon niveau, ce qui permet dâassurer un faible taux dâerreur, avec une faible latence. Par ailleurs, la complexitĂ© doit ĂȘtre limitĂ©e. Dans le but de dĂ©terminer des solutions technologiques modernes qui satisfont ces contraintes fortes, nous Ă©tudions dans la thĂšse des systĂšmes de communication sans fil MIMO codĂ©s. Dâabord, nous imposons un simple code convolutif rĂ©cursif systĂ©matique (RSC) pour limiter la complexitĂ© et la latence. En considĂ©rant des rĂ©cepteurs itĂ©ratifs, nous optimisons alors la performance en termes de taux dâerreur de ces systĂšmes en dĂ©finissant un prĂ©codage linĂ©aire MIMO et des techniques de mapping appropriĂ©es. Dans la deuxiĂšme partie de la thĂšse, nous remplaçons le RSC par un LDPC non-binaire (NB-LDPC). Nous proposons dâutiliser les techniques de prĂ©codage MIMO afin de rĂ©duire la complexitĂ© des rĂ©cepteurs des systĂšmes MIMO intĂ©grant des codes NB-LDPC. Enfin, nous proposons Ă©galement un nouvel algorithme de dĂ©codage itĂ©ratif Ă faible complexitĂ© adaptĂ© 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 lâavenir de la cinquiĂšme gĂ©nĂ©ration (5G) des rĂ©seaux mobiles. Ces normes exigent de hauts dĂ©bits de donnĂ©es et une qualitĂ© de service de trĂšs bon niveau, ce qui permet dâassurer un faible taux dâerreur, avec une faible latence. Par ailleurs, la complexitĂ© doit ĂȘtre limitĂ©e. Dans le but de dĂ©terminer des solutions technologiques modernes qui satisfont ces contraintes fortes, nous Ă©tudions dans la thĂšse des systĂšmes de communication sans fil MIMO codĂ©s. Dâabord, nous imposons un simple code convolutif rĂ©cursif systĂ©matique (RSC) pour limiter la complexitĂ© et la latence. En considĂ©rant des rĂ©cepteurs itĂ©ratifs, nous optimisons alors la performance en termes de taux dâerreur de ces systĂšmes en dĂ©finissant un prĂ©codage linĂ©aire MIMO et des techniques de mapping appropriĂ©es. Dans la deuxiĂšme partie de la thĂšse, nous remplaçons le RSC par un LDPC non-binaire (NB-LDPC). Nous proposons dâutiliser les techniques de prĂ©codage MIMO afin de rĂ©duire la complexitĂ© des rĂ©cepteurs des systĂšmes MIMO intĂ©grant des codes NB-LDPC. Enfin, nous proposons Ă©galement un nouvel algorithme de dĂ©codage itĂ©ratif Ă faible complexitĂ© adaptĂ© 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
International audienc
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
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
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
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