Papers by M.Carmen Lucas-Estañ
IEEE Transactions on Industrial Informatics , 2020
Factories are evolving into fully digitalized and networked structures for more adaptive and agil... more Factories are evolving into fully digitalized and networked structures for more adaptive and agile production ecosystems in the context of the Industry 4.0. Wireless communications will be a technical pillar of this evolution as it improves the reconfigurability of factories and the integration of mobile robots and objects. The integration of industrial wireless networks into the Industry 4.0 requires solutions capable to support highly reliable and deterministic low latency communications. This is particularly challenging for mobile industrial applications with constantly changing link quality conditions. This study experimentally evaluates for the first time the capacity of diversity and redundancy to improve the reliability and latency of wireless networks for mobile industrial applications. To this aim, a prototype is built in a collaborative robotics experimental facility. The prototype wirelessly connects a dual-arm robot and a mobile robot that collects and supplies components to the dual-arm robot. The prototype implements redundancy and diversity (using multipath TCP) for the wireless connections between both robots. The conducted trials show that both techniques improve the reliability of mobile industrial wireless communications even under the presence of interference. However, redundancy achieves lower latency levels and represents then the most attractive solution to support mobile industrial applications.
IEEE Access, 2019
Network slicing is a novel 5G paradigm that exploits the virtualization and softwarization of net... more Network slicing is a novel 5G paradigm that exploits the virtualization and softwarization of networks to create different logical network instances over a common network infrastructure. Each instance is tailored for specific Quality of Service (QoS) profiles so that network slicing can simultaneously support several services with diverse requirements. Network slicing can be applied at the Core Network or at the Radio Access Network (RAN). RAN slicing is particularly relevant to support latency-sensitive or time-critical applications since the RAN accounts for a significant part of the end-to-end transmission latency. In this context, this study proposes a novel latency-sensitive 5G RAN slicing solution. The proposal includes schemes to design slices and partition (or allocate) radio resources among slices. These schemes are designed with the objective to satisfy both the rate and latency demands of diverse applications. In particular, this study considers applications with deterministic aperiodic, deterministic periodic and non-deterministic traffic. The latency-sensitive 5G RAN slicing proposal is evaluated in Industry 4.0 scenarios where stringent and/or deterministic latency requirements are common. However, it can be evolved to support other verticals with latency-sensitive or time-critical applications.
Sensors, 2019
5G and beyond networks are being designed to support the future digital society, where numerous s... more 5G and beyond networks are being designed to support the future digital society, where numerous sensors, machinery, vehicles and humans will be connected in the so-called Internet of Things (IoT). The support of time-critical verticals such as Industry 4.0 will be especially challenging, due to the demanding communication requirements of manufacturing applications such as motion control, control-to-control applications and factory automation, which will require the exchange of critical sensing and control information among the factory nodes. To this aim, important changes have been introduced in 5G for Ultra-Reliable and Low-Latency Communications (URLLC). One of these changes is the introduction of grant-free scheduling for uplink transmissions. The objective is to reduce latency by eliminating the need for User Equipments (UEs-sensors, devices or machinery) to request resources and wait until the network grants them. Grant-free scheduling can reserve radio resources for dedicated UEs or for groups of UEs. The latter option is particularly relevant to support applications with aperiodic or sporadic traffic and deterministic low latency requirements. In this case, when a UE has information to transmit, it must contend for the usage of radio resources. This can lead to potential packet collisions between UEs. 5G introduces the possibility of transmitting K replicas of the same packet to combat such collisions. Previous studies have shown that grant-free scheduling with K replicas and shared resources increases the packet delivery. However, relying upon the transmission of K replicas to achieve a target reliability level can result in additional delays, and it is yet unknown whether grant-free scheduling with K replicas and shared resources can guarantee very high reliability levels with very low latency. This is the objective of this study, that identifies the reliability and latency levels that can be achieved by 5G grant-free scheduling with K replicas and shared resources in the presence of aperiodic traffic, and as a function of the number of UEs, reserved radio resources and replicas K. The study demonstrates that current Fifth Generation New Radio (5G NR) grant-free scheduling has limitations to sustain stringent reliability and latency levels for aperiodic traffic.
IEEE Access, 2019
5G and beyond networks will offer multiple communication modes including device-to-device and mul... more 5G and beyond networks will offer multiple communication modes including device-to-device and multi-hop cellular (or UE-to-network relay) communications. Several studies have shown that these modes can significantly improve the Quality of Service (QoS), the spectrum and energy efficiency, and the network capacity. Recent studies have demonstrated that further gains can be achieved when integrating demand-driven opportunistic networking into Multi-Hop Cellular Networks (MCN). In opportunistic MCN connections, devices can exploit the delay tolerance of many mobile data services to search for the most efficient connections between nodes. The availability of multiple communication modes requires mode selection schemes capable to decide the optimum mode for each transmission. Mode selection schemes have been previously proposed to account for the introduction of D2D and MCN. However, existing mode selection schemes cannot integrate opportunistic MCN connections into the selection process. This paper advances the state of the art by proposing the first mode selection scheme capable to integrate opportunistic MCN communications within 5G and beyond networks. The conducted analysis demonstrates the potential of opportunistic MCN communications, and the capability of the proposed mode selection scheme to select the most adequate communication mode. INDEX TERMS 5G, mode selection, multi-hop cellular, opportunistic networking, UE-to-Network Relay, device-to-device, D2D, device-centric wireless networks.
Proceedings of the IEEE 24rd International Conference on Emerging Technologies and Factory Automation (ETFA 2019), 2019
5G networks can support the development of the Industry 4.0. To this aim, 5G must be able to guar... more 5G networks can support the development of the Industry 4.0. To this aim, 5G must be able to guarantee the deterministic latency requirements that characterize many industrial applications. This objective can be achieved using network slicing, a novel 5G paradigm that exploits the softwarization of networks to create different logical instances of the network over a common network infrastructure. Each instance is configured to support specific applications. Slicing can be applied at the Core Network or at the Radio Access Network (RAN). This study focuses on RAN slicing since the RAN typical accounts for a large part of the end-to-end delay. RAN slicing splits (and configures) resources at the RAN level between the slices in order to adequately serve nodes with a particular profile. This includes identifying the necessary radio resources per slice. To date, most proposals define slices in terms of the number of required radio resources. While this descriptor can account for bandwidth or rate requirements, it does not adequately reflect the latency requirements characteristic of many Industry 4.0 applications. This paper proposes a novel latency-based RAN slice descriptor and demonstrates that the new descriptor improves the capacity of RAN slicing to meet the latency requirements of Industry 4.0 applications with deterministic periodic traffic.
Electronics, 2019
In the present day, 5G and beyond networks are being designed to support the future increase of d... more In the present day, 5G and beyond networks are being designed to support the future increase of data traffic and service demands. To support such increase, 5G networks will incorporate device-centric technologies with adequate mechanisms to scale and handle the growing and very large number of connected devices and traffic demands. Device-centric technologies include Device-to-Device (D2D) communications and Multi-hop Cellular Networks (MCNs). In device-centric wireless networks, devices will be able to connect to the network using two different connection modes: through a traditional cellular connection, or through a multi-hop cellular connection based on D2D communications with intermediate mobile devices. Device-centric technologies will therefore provide new connectivity options and significant opportunities to enhance the capacity and efficiency of 5G networks. However, new challenges will need to be addressed. One of them is the selection of the most adequate connection mode for each mobile device, because it will be key to improve the network performance and efficiency. This work proposes a context-aware mode selection scheme capable of identifying and selecting the most adequate connection mode for each device under a wide range of deployment and operating conditions. The proposed scheme estimates the benefits and risks of each connection mode based on context information available at the base station guaranteeing low signaling overhead. The obtained results show that the proposed mode selection scheme helps achieving throughput gains higher than 200% compared to traditional single-hop cellular communications for devices at the cell edge, and significant gains are also achieved compared to other mode selection schemes implemented and evaluated.
Transactions on Industrial Informatics, 2019
Industry 4.0 will interconnect and digitalize traditional industries to enable smart and adaptabl... more Industry 4.0 will interconnect and digitalize traditional industries to enable smart and adaptable factories that efficiently utilize resources and integrate systems. A key enabler of this paradigm is the communications infrastructure that will support the ubiquitous connectivity of Cyber-Physical Production Systems. The integration of wireless networks will facilitate the dynamic reconfiguration of the factories of the future, and collection and management of large amounts of data. This vision requires reliable and low latency wireless links with the necessary bandwidth to support data intensive applications and spatio-temporal variations of data resulting from the reconfiguration of Industrial IoT systems. To this aim, this paper proposes a load balancing scheme that dynamically manages the wireless links based on their quality and the amount of data to be transmitted by each node. The proposed scheme avoids the saturation of channels, and significantly augments the reliability of industrial wireless networks in comparison with existing solutions.
With the fast-paced realization of the Industry 4.0 paradigm, completely centralized networking s... more With the fast-paced realization of the Industry 4.0 paradigm, completely centralized networking solutions will no longer be sufficient to meet the stringent requirements of the related industrial applications. Besides requiring fast response time and increased reliability, they will necessitate computational resources at the edge of the network, which demands advanced communication and data management techniques. In this paper, we provide an overview of the network communications and data management aspects for the Industry 4.0. Our global perspective is to understand the key communication and data management challenges and peculiarities for the effective realization of the fourth industrial revolution. To address these challenges, this paper proposes hybrid communications management and decentralized data distribution solutions supported by a hierarchical and multi-tier network architecture. The proposed solutions combine local and decentralized management with centralized decisions to efficiently use the available network resources and meet the requirements of Industry 4.0 applications. To this end, the distributed management entities interact in order to coordinate their decisions and ensure the correct operation of the whole network. Finally, the use of Radio Access Network (RAN) slicing is proposed to achieve the required flexibility to efficiently meet the stringent and varying communication and data management requirements of industrial applications.
Industrial wireless communications will be an important technology enabler for the Industry 4.0 p... more Industrial wireless communications will be an important technology enabler for the Industry 4.0 paradigm. However, the pervasive introduction of wireless communications in factories requires improving their reliability and capacity to support low latency communications. An approach to do so is through the introduction of redundancy. Several studies have analytically and through simulations demonstrated the benefits of exploiting redundancy in industrial wireless communications. This paper progresses the current state of the art by experimentally analyzing for the first time the benefits that redundancy in industrial wireless communications can provide to support mobile industrial applications. The analysis has been conducted in a collaborative robotics experimental facility under the framework of the H2020 AUTOWARE project.
Under the Industry 4.0 paradigm, factories of the future will be digitalized and networked factor... more Under the Industry 4.0 paradigm, factories of the future will be digitalized and networked factories where components will be able to communicate with each other, and intelligence will be spread among the different elements of the production systems. Different industrial applications will coexist in the same environment demanding very different and stringent communication requirements in terms of latency, reliability and data rate. These applications can vary from virtual reality applications that require high throughput levels to time-critical automation processes demanding low data rates and ultra-high latency. The communication network will be one of the key technological enablers of Industry 4.0. In this context, this paper proposes a hierarchical management architecture that allows the integration of different communication technologies. The proposed architecture considers the use of RAN Slicing and Cloud RAN as enabling technologies to achieve the flexibility, scalability and adaptation capabilities required to support the high-demanding and diverse industrial environment.
The Industry 4.0 paradigm alludes to a new industrial revolution where factories evolve towards d... more The Industry 4.0 paradigm alludes to a new industrial revolution where factories evolve towards digitalized and networked structures where intelligence is spread among the different elements of the production systems. Two key technological enablers to achieve the flexibility and efficiency sought for factories of the future are the communication networks and the data management schemes that will support connectivity and data distribution in Cyber-Physical Production Systems. Communications and data management must be built upon a flexible and reliable architecture to be able to efficiently meet the stringent and varying requirements in terms of latency, reliability and data rates demanded by industrial applications, and with particular attention on time-critical automation. To this aim, this paper proposes the use of heterogeneous communication technologies integrated in a hierarchical communications and data management architecture where decentralized and local management decisions are coordinated by a central orchestrator that ensures the efficient global operation of the system. Industrial applications are organized in different tiers where different management strategies are applied to satisfy their different requirements in terms of latency and reliability. The use of virtualization and softwarization technologies as RAN Slicing and Cloud RAN will allow to achieve the flexibility, scalability and adaptation capabilities required to support the high-demanding and diverse industrial environment.
Underlaying Device-to-Device (D2D) communications can increase the spectral efficiency of cellula... more Underlaying Device-to-Device (D2D) communications can increase the spectral efficiency of cellular networks when sharing part of the spectrum with cellular users. This requires radio resource allocation policies capable to limit and control the interference between D2D and cellular communications. Many of the proposed policies are centralized, and require the base station to decide which resources should be allocated to each D2D transmission. Centralized schemes can efficiently control interference levels, but their feasibility can be compromised by their complexity and signaling overhead. To address this constraint, this paper proposes DiRAT, a distributed radio resource allocation scheme for D2D communications underlaying cellular networks. With DiRAT, the D2D nodes locally select their radio resources from a pool created by the cellular network in order to control the interference generated to the primary cellular users. DiRAT includes a control mechanism to ensure that the user QoS requirements are satisfied. This study demonstrates that DiRAT can increase the network capacity while avoiding or limiting the degradation of the performance of the primary cellular users. DiRAT also significantly reduces the complexity and overhead compared to existing centralized and distributed schemes.
Device-centric wireless technologies, such as Device-to-Device (D2D) communications, will provide... more Device-centric wireless technologies, such as Device-to-Device (D2D) communications, will provide new ways of connectivity and significant opportunities to enhance the capacity and efficiency of 5G networks. Underlaying D2D communications will share radio resources with cellular communications and novel radio resource management schemes need to be defined to control the interference between D2D and cellular nodes. This paper proposes a distributed radio resource allocation scheme for D2D communications underlaying cellular networks. The proposed scheme allows D2D nodes to select radio resources from a pool identified by the infrastructure to limit the interference caused by D2D links to cellular communications. The proposed scheme includes a control process in order to guarantee that user QoS requirements are satisfied. The conducted study demonstrates that the proposed scheme significantly improves spectral efficiency of traditional cellular systems while guaranteeing QoS requirements to both cellular and D2D communications.
Device-to-Device (D2D) communications can increase the spectral efficiency of future cellular net... more Device-to-Device (D2D) communications can increase the spectral efficiency of future cellular networks when sharing part of the cellular spectrum. Radio resource allocation mechanisms are then necessary to control the interference that D2D and cellular transmissions can generate to each other. Most of the existing allocation schemes rely on the knowledge of the channel gain of all possible links between cellular and D2D nodes. This paper proposes to reduce the complexity cost and signalling overhead of the allocation process by using location information available at the network level. Using this information, the base station assigns radio resources to new D2D transmissions with the objective to control and limit the interference to the primary cellular users and existing D2D transmissions. The proposed radio resource allocation scheme continuously monitors that the user QoS requirements are satisfied. If it is not the case, it dynamically modifies the resource allocation to the interfering D2D transmissions. The proposed scheme achieves performance levels similar to that obtained with an optimized centralized allocation scheme, but with a significantly lower complexity cost and signaling overhead.
The FASyS (Absolutely Safe and Healthy Factory) project, aligned with the European Factories of t... more The FASyS (Absolutely Safe and Healthy Factory) project, aligned with the European Factories of the Future (FoF) concept, has been set-up to develop a new factory model aimed at minimizing the risks to the worker's health and safety, and guarantee their welfare and comfort in machining, handling and assembly factories. To this aim, ICT (Information and Communication Technologies) and wireless communication technologies in particular may represent very valuable tools to implement distributed and mobile sensing applications capable to continuously sense the working environment and the workers' health and safety conditions. The effective deployment of such applications in critical environments, like the industrial one, require the availability of a platform capable to monitor the operation and performance of the heterogeneous wireless networks that will connect the mobile sensors to remote control centers. This paper presents the platform implemented for this purpose in the context of the FASyS project. In addition to monitoring the status of heterogeneous wireless networks, the implemented platform provides the capability to reconfigure remotely the communication settings of wireless nodes based on possible malfunctioning or QoS degradation notifications. These functionalities will help guaranteeing the reliable and robust wireless communications required in industrial environments to implement innovative labor risk prevention applications exploiting ICT technologies.
The study and design of Joint Radio Resource Management (JRRM) techniques is a key and challengin... more The study and design of Joint Radio Resource Management (JRRM) techniques is a key and challenging aspect in future heterogeneous wireless systems where different Radio Access Technologies (RAT) will physically coexist. In these systems, the total available radio resources need to be used in a coordinated way to guarantee adequate satisfaction levels to all users, and maximize the system revenues. In addition to carry out an efficient use of the available radio resources, JRRM algorithms need to exhibit good computational performance to guarantee their future implementation viability. In this context, this paper proposes novel JRRM techniques based on linear programming techniques, and investigates their computational cost when implemented in DSP platforms commonly used in mobile-based stations. The obtained results demonstrate the feasibility to implement the proposed JRRM algorithms in future heterogeneous wireless systems.
Proceedings of the IEEE/IFIP Wireless Days Conference 2013 (WD 2013)
Multi-hop Cellular Networks using Mobile Relays (MCN-MRs) are being investigated to help address ... more Multi-hop Cellular Networks using Mobile Relays (MCN-MRs) are being investigated to help address certain limitations of traditional single-hop cellular communications. A key element of MCN-MR technologies is the mode selection scheme that selects the most adequate connection mode (traditional single hop cellular or multi-hop link) for each transmission. This paper proposes a novel mode selection scheme that uses context information to select the connection mode, and can adapt its decisions to the operating conditions. This study shows that the proposed scheme outperforms distance-based mode selection schemes, and helps improving the MCN-MR performance with respect to single-hop cellular communications.
Heterogeneous wireless systems are characterized by the physical coexistence of a variety of radi... more Heterogeneous wireless systems are characterized by the physical coexistence of a variety of radio access technologies with different, but also complementary, technical characteristics and performance. A key aspect of heterogeneous systems is then the implementation of efficient joint radio resource management mechanisms. In this context, this paper presents and evaluates novel joint radio resource management techniques based on the CEA bankruptcy distribution rule. The proposed policies base their distribution decisions on the system conditions and the varying quality of service requirements present in multimedia scenarios. The obtained results demonstrate that the proposed policies can efficiently distribute the radio resources with a low computational cost.
The transmission of bandwidth-demanding multimedia applications in capacity-constrained mobile ra... more The transmission of bandwidth-demanding multimedia applications in capacity-constrained mobile radio networks requires optimizing the usage and assignment of radio resources following the varying quality of service requirement characteristics of multimedia traffic environments. Considering the capacity of the bankruptcy theory to deal with situations where the demand for resources is higher than its availability, this work proposes the application of bankruptcy theories to design efficient radio resource management policies that provide the highest possible quality of service levels while guaranteeing user fairness.
Wireless systems will be characterized by the coexistence of heterogeneous Radio Access Technolog... more Wireless systems will be characterized by the coexistence of heterogeneous Radio Access Technologies (RATs) with different, but also complementary, performance and technical characteristics. These heterogeneous wireless networks will provide network operators the possibility to efficiently and coordinately use the heterogeneous radio resources, for which novel Joint Radio Resource Management (JRRM) policies need to be designed. In this context, this work proposes and evaluates a JRRM policy that simultaneously determines for each user an adequate combination of RAT and number of radio resources within such RAT to guarantee the user/service QoS requirements, and efficiently distribute the radio resources considering a user fairness approach aimed at maximizing the system capacity. To this aim, the JRRM algorithm, which takes into account the discrete nature of radio resources, is based on integer linear programming optimization mechanisms.
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Papers by M.Carmen Lucas-Estañ