International audienceRecently, iterative receiver combining multiple-input multiple-output (MIMO... more International audienceRecently, iterative receiver combining multiple-input multiple-output (MIMO) detection withchannel decoding has been widely considered to achieve near-capacity performance and reliable highdata rate transmission, for future wireless communication systems. However, such iterativeprocessing increases the computational complexity at the receiver. In this paper, the computationalcomplexity of MIMO detection algorithms combined with turbo decoding is investigated. We firstpresent an overview of the family of MIMO detection algorithms based on sphere decoding, K-Bestdecoding, and interference cancellation. A recently proposed low-complexity K-Best decoder(LC-K-Best) is also presented. Moreover, we analyze the convergence of combining these detectionalgorithms with the turbo decoder using the extrinsic information transfer (EXIT) chart.Consequently, a new scheduling order of the number of iterations for the iterative process isproposed. Several system configurations a...
2018 European Conference on Networks and Communications (EuCNC), 2018
The 5G network is on the verge of being deployed, as the first set of 5G features have just been ... more The 5G network is on the verge of being deployed, as the first set of 5G features have just been standardized by 3GPP. N ever the less several unsolved issues endanger an effective and profitable deployment of 5G systems, to address which this paper proposes some significant enhancements in the backhaul, at MAC, and at RRM layers. Leveraging on a new concept called extended Dynamic Spectrum Access (eDSA), novel algorithms and protocols are proposed, one of which is based on the Filter Bank Multicarrier (FBMC) technology. The results are mainly taken from the work of SPEED-5G, an EU-funded research project.
Abstract Recently, LoRaWAN has been considered a promising technology for large-scale IoT applica... more Abstract Recently, LoRaWAN has been considered a promising technology for large-scale IoT applications owing to its ability to achieve low power and long range communications. However, LoRaWAN is limited using Aloha random access scheme. When in dense scenarios, such scheme leads to a high number of collisions, thus severely impacts the reliability and scalability of LoRaWAN. In this paper, we investigate the impact of scalability and densification of nodes and gateways on the system reliability taking into account the capture effect. We propose an optimization problem to derive the node distribution at different spreading factors (SF) in LoRaWAN networks with multiple gateways. We then introduce an adaptive algorithm that enables to easily implement SF optimization by adjusting the signal-to-noise ratio thresholds. Moreover, the performance of the proposed algorithm is compared with the performance of legacy LoRaWAN and relevant algorithms from the state-of-the-art. Simulation results show that the proposed algorithm significantly outperforms the state-of-the-art algorithms, and improves the throughput and packet delivery ratio of the network.
The fifth generation (5G) of wireless networks is currently under investigation in order to addre... more The fifth generation (5G) of wireless networks is currently under investigation in order to address the well-known challenges of the high capacity demands and traffic volume. The promising solutions to meet these targets can be achieved through ultra-densification, efficient use of spectrum and advanced filtered modulation techniques. In this paper, we present an enhanced MAC protocol for 5G small cells operating at 5 GHz and assuming an FBMC physical layer. The proposed MAC design consists of scheduled-based and contention-based access schemes and involves a listen before talk (LBT) procedure to comply with ETSI regulations. The performance of the proposed FBMC-MAC design is then evaluated in dense deployment scenarios under different PHY/MAC parameter settings. Moreover, we study the performance of FBMC-MAC systems in the context of coexistence with WiFi systems.
Recently, LoRaWAN has emerged as a promising technology for the Internet of things (IoT), owing i... more Recently, LoRaWAN has emerged as a promising technology for the Internet of things (IoT), owing its ability to support low-power and long-range communications. However, real-world deployment and network optimization require accurate path-loss (PL) modeling, so as to estimate network coverage, performance, and profitability. For that reason, in this work, LoRaWAN radio channel is investigated in the 868 MHz band. Extensive measurement campaigns were carried out in both indoor and outdoor environments at urban and rural locations in Lebanon (Saint Joseph University of Beirut campus, Beirut city, and Bekaa valley). Based on empirical results, PL models are developed for LoRaWAN communications and compared with widely used empirical models. Moreover, the performance and the coverage of LoRaWAN deployment are evaluated based on real measurements. The results show that the proposed PL models are accurate and simple to be applied in Lebanon and other similar locations. Coverage ranges up to 8 km and 45 km were obtained in urban and rural areas, respectively. This reveals the reliability of this promising technology for long-range IoT communications.
Multiple-input multiple-output (MIMO) technology in combination with channel coding technique is ... more Multiple-input multiple-output (MIMO) technology in combination with channel coding technique is a promising solution for reliable high data rate transmission in future wireless communication systems. However, these technologies pose significant challenges for the design of an iterative receiver. In this paper, an efficient receiver combining soft-input soft-output (SISO) detection based on low-complexity K-Best (LC-K-Best) decoder with various forward error correction codes, namely, LTE turbo decoder and LDPC decoder, is investigated. We first investigate the convergence behaviors of the iterative MIMO receivers to determine the required inner and outer iterations. Consequently, the performance of LC-K-Best based receiver is evaluated in various LTE channel environments and compared with other MIMO detection schemes. Moreover, the computational complexity of the iterative receiver with different channel coding techniques is evaluated and compared with different modulation orders an...
2016 23rd International Conference on Telecommunications (ICT), 2016
In recent years, iterative receiver has been widely considered since it is able to achieve high d... more In recent years, iterative receiver has been widely considered since it is able to achieve high data rates and reliable communications for coded MIMO-OFDM systems. However, such a receiver is extremely challenging in practical implementation. In this paper, we present an efficient fixed-point arithmetic of iterative receiver based on low-complexity K-Best decoder in order to reduce the hardware costs in terms of area and execution time. The performance of fixed-point receiver is then evaluated with different modulation orders and channel models. Moreover, a testbed for MIMO-OFDM system using wireless open access research platform (WARP) is introduced in order to evaluate the performance of the receiver under real system conditions.
LoRaWAN is a promising technology for the internet of things (IoT) in order to support low power ... more LoRaWAN is a promising technology for the internet of things (IoT) in order to support low power and long-range communications. However, real-world deployment and network optimization require an accurate path-loss modeling in order to estimate network coverage and performance. We carried out extensive measurement campaigns in both indoor and outdoor environments considering urban and rural areas in three locations in Lebanon (Saint Joseph University campus, Beirut city, and Bekaa valley). We further consider 3 different antennas heights of the end-device (0.2m-3m). This dataset provides these measurements campaigns, which enable us to derive Path-loss (PL) models for Lora communication. A text file "Readme_data" is provided to describe the measurements in addition a Matlab function of the proposed model "Path-Loss-Model" is given.
EURASIP Journal on Wireless Communications and Networking, 2015
Recently, iterative receiver combining multiple-input multiple-output (MIMO) detection with chann... more Recently, iterative receiver combining multiple-input multiple-output (MIMO) detection with channel decoding has been widely considered to achieve near-capacity performance and reliable high data rate transmission, for future wireless communication systems. However, such iterative processing increases the computational complexity at the receiver. In this paper, the computational complexity of MIMO detection algorithms combined with turbo decoding is investigated. We first present an overview of the family of MIMO detection algorithms based on sphere decoding, K-Best decoding, and interference cancellation. A recently proposed low-complexity K-Best decoder (LC-K-Best) is also presented. Moreover, we analyze the convergence of combining these detection algorithms with the turbo decoder using the extrinsic information transfer (EXIT) chart. Consequently, a new scheduling order of the number of iterations for the iterative process is proposed. Several system configurations are developed and compared in terms of performance and complexity. Simulations and analytical results show that the new scheduling provides good performance with a large saving in the complexity. Additionally, the LC-K-Best decoder shows a good performance-complexity tradeoff, and it is therefore suitable for parallel and pipeline architectures that can meet high throughput requirements.
Recently, iterative processing has been widely considered to achieve near-capacity performance an... more Recently, iterative processing has been widely considered to achieve near-capacity performance and reliable high data rate transmission, for future wireless communication systems. However, such an iterative processing poses significant challenges for efficient receiver design. In this thesis, iterative receiver combining multiple-input multiple-output (MIMO) detection with channel decoding is investigated for high data rate transmission. The convergence, the performance and the computational complexity of the iterative receiver for MIMO-OFDM system are considered. First, we review the most relevant hard-output and soft-output MIMO detection algorithms based on sphere decoding, K-Best decoding, and interference cancellation. Consequently, a low-complexity K-best (LCK- Best) based decoder is proposed in order to substantially reduce the computational complexity without significant performance degradation. We then analyze the convergence behaviors of combining these detection algorithm...
Ultra-densification and efficient spectrum utilization are key features for the next 5G wireless ... more Ultra-densification and efficient spectrum utilization are key features for the next 5G wireless networks to address the well-known challenges of high capacity demands and mobile data traffic explosion. In this article, a physical layer and a medium access control (MAC) sublayer are presented for small cells to operate in the 5 GHz unlicensed national information infrastructure (UNII) band. The physical layer is based on filter bank multi-carrier modulation able to achieve better spectral efficiency and access flexibility. The MAC protocol is based on beacon-enabled superframe consisting of scheduled and contention access schemes. The proposed UNII-MAC design relies on a listen-before-talk (LBT) procedure in order to comply with ETSI regulations and to fairly coexist with neighboring systems sharing the same band. The performance of the UNII-MAC is then evaluated in dense indoor/outdoor deployment scenarios under various parameters and traffic patterns. Moreover, the coexistence between UNII-MAC and WiFi systems is reported. Based on the obtained results, we provide recommendations for 5G small cell deployment in dense environments.
International audienceRecently, iterative receiver combining multiple-input multiple-output (MIMO... more International audienceRecently, iterative receiver combining multiple-input multiple-output (MIMO) detection withchannel decoding has been widely considered to achieve near-capacity performance and reliable highdata rate transmission, for future wireless communication systems. However, such iterativeprocessing increases the computational complexity at the receiver. In this paper, the computationalcomplexity of MIMO detection algorithms combined with turbo decoding is investigated. We firstpresent an overview of the family of MIMO detection algorithms based on sphere decoding, K-Bestdecoding, and interference cancellation. A recently proposed low-complexity K-Best decoder(LC-K-Best) is also presented. Moreover, we analyze the convergence of combining these detectionalgorithms with the turbo decoder using the extrinsic information transfer (EXIT) chart.Consequently, a new scheduling order of the number of iterations for the iterative process isproposed. Several system configurations a...
2018 European Conference on Networks and Communications (EuCNC), 2018
The 5G network is on the verge of being deployed, as the first set of 5G features have just been ... more The 5G network is on the verge of being deployed, as the first set of 5G features have just been standardized by 3GPP. N ever the less several unsolved issues endanger an effective and profitable deployment of 5G systems, to address which this paper proposes some significant enhancements in the backhaul, at MAC, and at RRM layers. Leveraging on a new concept called extended Dynamic Spectrum Access (eDSA), novel algorithms and protocols are proposed, one of which is based on the Filter Bank Multicarrier (FBMC) technology. The results are mainly taken from the work of SPEED-5G, an EU-funded research project.
Abstract Recently, LoRaWAN has been considered a promising technology for large-scale IoT applica... more Abstract Recently, LoRaWAN has been considered a promising technology for large-scale IoT applications owing to its ability to achieve low power and long range communications. However, LoRaWAN is limited using Aloha random access scheme. When in dense scenarios, such scheme leads to a high number of collisions, thus severely impacts the reliability and scalability of LoRaWAN. In this paper, we investigate the impact of scalability and densification of nodes and gateways on the system reliability taking into account the capture effect. We propose an optimization problem to derive the node distribution at different spreading factors (SF) in LoRaWAN networks with multiple gateways. We then introduce an adaptive algorithm that enables to easily implement SF optimization by adjusting the signal-to-noise ratio thresholds. Moreover, the performance of the proposed algorithm is compared with the performance of legacy LoRaWAN and relevant algorithms from the state-of-the-art. Simulation results show that the proposed algorithm significantly outperforms the state-of-the-art algorithms, and improves the throughput and packet delivery ratio of the network.
The fifth generation (5G) of wireless networks is currently under investigation in order to addre... more The fifth generation (5G) of wireless networks is currently under investigation in order to address the well-known challenges of the high capacity demands and traffic volume. The promising solutions to meet these targets can be achieved through ultra-densification, efficient use of spectrum and advanced filtered modulation techniques. In this paper, we present an enhanced MAC protocol for 5G small cells operating at 5 GHz and assuming an FBMC physical layer. The proposed MAC design consists of scheduled-based and contention-based access schemes and involves a listen before talk (LBT) procedure to comply with ETSI regulations. The performance of the proposed FBMC-MAC design is then evaluated in dense deployment scenarios under different PHY/MAC parameter settings. Moreover, we study the performance of FBMC-MAC systems in the context of coexistence with WiFi systems.
Recently, LoRaWAN has emerged as a promising technology for the Internet of things (IoT), owing i... more Recently, LoRaWAN has emerged as a promising technology for the Internet of things (IoT), owing its ability to support low-power and long-range communications. However, real-world deployment and network optimization require accurate path-loss (PL) modeling, so as to estimate network coverage, performance, and profitability. For that reason, in this work, LoRaWAN radio channel is investigated in the 868 MHz band. Extensive measurement campaigns were carried out in both indoor and outdoor environments at urban and rural locations in Lebanon (Saint Joseph University of Beirut campus, Beirut city, and Bekaa valley). Based on empirical results, PL models are developed for LoRaWAN communications and compared with widely used empirical models. Moreover, the performance and the coverage of LoRaWAN deployment are evaluated based on real measurements. The results show that the proposed PL models are accurate and simple to be applied in Lebanon and other similar locations. Coverage ranges up to 8 km and 45 km were obtained in urban and rural areas, respectively. This reveals the reliability of this promising technology for long-range IoT communications.
Multiple-input multiple-output (MIMO) technology in combination with channel coding technique is ... more Multiple-input multiple-output (MIMO) technology in combination with channel coding technique is a promising solution for reliable high data rate transmission in future wireless communication systems. However, these technologies pose significant challenges for the design of an iterative receiver. In this paper, an efficient receiver combining soft-input soft-output (SISO) detection based on low-complexity K-Best (LC-K-Best) decoder with various forward error correction codes, namely, LTE turbo decoder and LDPC decoder, is investigated. We first investigate the convergence behaviors of the iterative MIMO receivers to determine the required inner and outer iterations. Consequently, the performance of LC-K-Best based receiver is evaluated in various LTE channel environments and compared with other MIMO detection schemes. Moreover, the computational complexity of the iterative receiver with different channel coding techniques is evaluated and compared with different modulation orders an...
2016 23rd International Conference on Telecommunications (ICT), 2016
In recent years, iterative receiver has been widely considered since it is able to achieve high d... more In recent years, iterative receiver has been widely considered since it is able to achieve high data rates and reliable communications for coded MIMO-OFDM systems. However, such a receiver is extremely challenging in practical implementation. In this paper, we present an efficient fixed-point arithmetic of iterative receiver based on low-complexity K-Best decoder in order to reduce the hardware costs in terms of area and execution time. The performance of fixed-point receiver is then evaluated with different modulation orders and channel models. Moreover, a testbed for MIMO-OFDM system using wireless open access research platform (WARP) is introduced in order to evaluate the performance of the receiver under real system conditions.
LoRaWAN is a promising technology for the internet of things (IoT) in order to support low power ... more LoRaWAN is a promising technology for the internet of things (IoT) in order to support low power and long-range communications. However, real-world deployment and network optimization require an accurate path-loss modeling in order to estimate network coverage and performance. We carried out extensive measurement campaigns in both indoor and outdoor environments considering urban and rural areas in three locations in Lebanon (Saint Joseph University campus, Beirut city, and Bekaa valley). We further consider 3 different antennas heights of the end-device (0.2m-3m). This dataset provides these measurements campaigns, which enable us to derive Path-loss (PL) models for Lora communication. A text file "Readme_data" is provided to describe the measurements in addition a Matlab function of the proposed model "Path-Loss-Model" is given.
EURASIP Journal on Wireless Communications and Networking, 2015
Recently, iterative receiver combining multiple-input multiple-output (MIMO) detection with chann... more Recently, iterative receiver combining multiple-input multiple-output (MIMO) detection with channel decoding has been widely considered to achieve near-capacity performance and reliable high data rate transmission, for future wireless communication systems. However, such iterative processing increases the computational complexity at the receiver. In this paper, the computational complexity of MIMO detection algorithms combined with turbo decoding is investigated. We first present an overview of the family of MIMO detection algorithms based on sphere decoding, K-Best decoding, and interference cancellation. A recently proposed low-complexity K-Best decoder (LC-K-Best) is also presented. Moreover, we analyze the convergence of combining these detection algorithms with the turbo decoder using the extrinsic information transfer (EXIT) chart. Consequently, a new scheduling order of the number of iterations for the iterative process is proposed. Several system configurations are developed and compared in terms of performance and complexity. Simulations and analytical results show that the new scheduling provides good performance with a large saving in the complexity. Additionally, the LC-K-Best decoder shows a good performance-complexity tradeoff, and it is therefore suitable for parallel and pipeline architectures that can meet high throughput requirements.
Recently, iterative processing has been widely considered to achieve near-capacity performance an... more Recently, iterative processing has been widely considered to achieve near-capacity performance and reliable high data rate transmission, for future wireless communication systems. However, such an iterative processing poses significant challenges for efficient receiver design. In this thesis, iterative receiver combining multiple-input multiple-output (MIMO) detection with channel decoding is investigated for high data rate transmission. The convergence, the performance and the computational complexity of the iterative receiver for MIMO-OFDM system are considered. First, we review the most relevant hard-output and soft-output MIMO detection algorithms based on sphere decoding, K-Best decoding, and interference cancellation. Consequently, a low-complexity K-best (LCK- Best) based decoder is proposed in order to substantially reduce the computational complexity without significant performance degradation. We then analyze the convergence behaviors of combining these detection algorithm...
Ultra-densification and efficient spectrum utilization are key features for the next 5G wireless ... more Ultra-densification and efficient spectrum utilization are key features for the next 5G wireless networks to address the well-known challenges of high capacity demands and mobile data traffic explosion. In this article, a physical layer and a medium access control (MAC) sublayer are presented for small cells to operate in the 5 GHz unlicensed national information infrastructure (UNII) band. The physical layer is based on filter bank multi-carrier modulation able to achieve better spectral efficiency and access flexibility. The MAC protocol is based on beacon-enabled superframe consisting of scheduled and contention access schemes. The proposed UNII-MAC design relies on a listen-before-talk (LBT) procedure in order to comply with ETSI regulations and to fairly coexist with neighboring systems sharing the same band. The performance of the UNII-MAC is then evaluated in dense indoor/outdoor deployment scenarios under various parameters and traffic patterns. Moreover, the coexistence between UNII-MAC and WiFi systems is reported. Based on the obtained results, we provide recommendations for 5G small cell deployment in dense environments.
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Papers by Rida Chall