Ana Garcia Armada

Ana Garcia Armada
University Carlos III de Madrid | UC3M · Department of Signal Theory and Communications

PhD

About

261
Publications
26,125
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2,669
Citations
Citations since 2017
126 Research Items
1422 Citations
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20172018201920202021202220230100200300
20172018201920202021202220230100200300
Additional affiliations
January 1999 - December 2012
Universidad Carlos III de Madrid
January 1998 - present

Publications

Publications (261)
Preprint
Full-text available
In recent years, advances in immersive multimedia technologies, such as extended reality (XR) technologies, have led to more realistic and user-friendly devices. However, these devices are often bulky and uncomfortable, still requiring tether connectivity for demanding applications. The deployment of the fifth generation of telecommunications techn...
Article
Vehicle-to-vehicle (V2V) communications are one of the most promising 6G scenarios. However, V2V communications demand high data rates and extremely low-latency requirements that are difficult to satisfy nowadays. Recently, vehicular visible light communications (V-VLC) have been proposed as a promising technology to guarantee such requirements. Mu...
Article
Non-coherent (NC) schemes combined with massive antenna arrays are proposed to replace traditional coherent schemes in scenarios which require an excessive number of reference signals, since NC approaches avoid channel estimation and equalization. Differential M -ary phase shift keying is one of the most appealing NC schemes due to its implementa...
Article
Full-text available
The Reconfigurable Intelligent Surface (RIS) constitutes one of the prominent technologies for the 6th Generation (6G) of wireless communications. It is envisioned to enhance signal coverage in cases where obstacles block direct communication from Base Stations (BSs), and when high carrier frequencies are used that are sensitive to attenuation loss...
Conference Paper
Many of the new mobile communication devices will be things that power and monitor our homes, city infrastructure and transport. Controlling drones thousands of miles away, performing remote surgeries or being immersed in video with no latency will also be a huge game changer. Those are some of the few things that make the fifth generation (5G) a r...
Article
Presents information and current topics of interest to the global communications industry.
Preprint
Full-text available
The Reconfigurable Intelligent Surface (RIS) constitutes one of the prominent technologies for the next generation of wireless communications. It is envisioned to enhance the signal coverage in cases when the direct link of the communication is weak. Recently, beam training based on codebook selection is proposed to obtain the optimized phase confi...
Article
Presents information and current topics of interest to the global communications industry.
Preprint
Full-text available
Reflecting Surfaces (RSs) are being lately envisioned as an energy efficient solution capable of enhancing the signal coverage in cases where obstacles block the direct communication from Base Stations (BSs), especially at high frequency bands due to attenuation loss increase. In the current literature, wireless communications via RSs are exclusive...
Article
Augmented reality (AR) has been presented lately as one of the key technology fields in which 5G networks can become a disruptive tool, raising interest from both industry and academia. The main goal of this article is to extend the current state of the art of distributed AR studies and implementations by extracting the main AR algorithms' offloadi...
Article
Reports on ComSoc global activities, events, and meetings.
Article
It is a great honor and privilege for me to serve as the President of IEEE Communications Society (ComSoc) in 2022–2023. IEEE ComSoc is a global professional organization that has been creating cutting-edge communications and networking technologies through its high-quality publications, premier conferences, technology standards, educational activi...
Article
Full-text available
The fifth-generation (5G) of networks is being deployed to provide a wide range of new services and to manage the accelerated traffic load of the existing networks. In the present-day networks, data has become more noteworthy than ever to infer about the traffic load and existing network infrastructure to minimize the cost of new 5G deployments. Id...
Article
Full-text available
A novel time division duplex massive MIMO technique is proposed based on performing a pilot-less channel estimation in the uplink (UL) utilizing reconstructed differentially encoded data. Spatial multiplexing and differentially encoded data is applied both in the UL and in the downlink (DL). In this system, a reference signal is the first one of th...
Article
Full-text available
The Reconfigurable Intelligent Surface (RIS) constitutes one of the prominent technologies for the next generation of wireless communications. It is envisioned to enhance the signal coverage in cases when the direct link of the communication is weak. Recently, beam training based on codebook selection is proposed to obtain the optimized phase confi...
Article
Constant envelope orthogonal frequency division multiplexing (CE-OFDM) is a multi-carrier waveform with 0 dB peak-to-average power ratio (PAPR). This property enables the exploitation of multi-carrier waveforms with non-linear power amplifiers, avoiding the undesirable clipping effects. However, the existing channel estimation techniques designed f...
Article
This paper introduces a novel waveform for wireless communication, denoted as Frequency-Modulated Orthogonal Frequency-Division Multiplexing (FM-OFDM). By frequency-modulating an OFDM signal and further defining a suitable cutoff subcarrier, the resulting constant-envelope waveform (ensuring a low Peak to Average Power Ratio) exhibits strong robust...
Article
Full-text available
An advantage of using the composite fading models (CFMs) is their ability to concurrently address the impact of multi-path and shadowing phenomena on the system performance in wireless communications. A Fisher-Snedecor (FS) F CFM has been recently proposed as an experimentally verified and tractable fading model that can be efficiently applied for...
Article
Pilot-pouring superimposed training (PPST) is a novel channel estimation technique specially designed for cyclic block filtered multi-tone (CB-FMT), where the pilot symbols are poured into the subcarriers taking advantage of the power left unused by the data symbols. Hence, since this technique is based on superimposed training (ST) principles, the...
Article
Full-text available
The Fisher–Snedecor (F-S) F distribution has recently been introduced as a tractable turbulence-induced (TI) fading model that fits well with the experimental data. This paper provides a performance evaluation of a free-space optical (FSO) re-configurable intelligent surface (RIS)-assisted communications (ACs) link over the F-S F TI fading channels...
Article
This letter focuses on the pilot contamination problem in the uplink and downlink of cell-free massive multiple-input multiple-output networks with different degrees of cooperation between access points. The optimum minimum mean square error processing can take advantage of large-scale fading coefficients for canceling the interference of pilot-sha...
Preprint
This letter focuses on the pilot contamination problem in the uplink and downlink of cell-free massive multiple-input multiple-output networks with different degrees of cooperation between access points. The optimum minimum mean square error processing can take advantage of large-scale fading coefficients for canceling the interference of pilot-sha...
Article
Heterogenous networks are mainly limited by interference. Nowadays, the advances in reconfigurable antennas allow us to implement blind interference alignment (BIA) schemes, which avoid the need for channel state information at the transmitter (CSIT) while providing an increasing multiplexing gain, i.e., the achievable DoF, as the number of users i...
Conference Paper
Full-text available
The FBMC is among the currently most researched techniques for signal processing and is explored here for passive optical access networks. This paper presents a performance analysis of the FBMC modulation format for applying in optical fiber and wireless communications. For analyzing, we realized simulation models that are based on well-known chara...
Article
One of the main problems faced by communication systems is the presence of skip-zones in the targeted areas. With the deployment of the fifth-generation mobile network, solutions are proposed to solve the signal loss due to obstruction by buildings, mountains, and atmospheric or weather conditions. Among these solutions, reconfigurable intelligent...
Article
Full-text available
Visible light communications (VLC) have been recently proposed to enhance the capacity of next generation of wireless services. Moreover, VLC networks usually comprise a large number of overlapping optical access points (APs). Moreover, each of these APs provides a small and confined area of coverage in order to generate satisfactory illumination....
Conference Paper
The arrival of the fifth generation (5G) of mobile communications is boosting vehicular communications, an important use case addressed in the recent years. LTE introduced a sidelink radio interface through which user equipment would communicate directly with no necessary dependence on the network, named PC5. 5G has defined its own sidelink interfa...
Preprint
Full-text available
The Reconfigurable Intelligent Surface (RIS) constitutes one of the prominent technologies for the next 6-th Generation (6G) of wireless communications. It is envisioned to enhance signal coverage in cases where obstacles block the direct communication from Base Stations (BSs), and when high carrier frequencies are used that are sensitive to attenu...
Article
Visible light communication (VLC) systems can support high data-rates for indoor communications. However, the inter-cell interference (ICI) in multi-cell VLC systems caused by resource sharing and the line-of-sight (LoS) blockage problem are significant challenges that cannot be neglected in the design and analysis of VLC systems. This letter studi...
Preprint
Visible light communication (VLC) systems can support high data-rates for indoor communications. However, the inter-cell interference (ICI) in multi-cell VLC systems caused by resource sharing and the line-of-sight (LoS) blockage problem are significant challenges that cannot be neglected in the design and analysis of VLC systems. This letter studi...
Preprint
Full-text available
One of the main problems faced by communication systems is the presence of skip-zones in the targeted areas. With the deployment of the fifth-generation mobile network, solutions are proposed to solve the signal loss due to obstruction by buildings, mountains, and atmospheric or weather conditions. Among these solutions, re-configurable intelligent...
Article
Cyclic block filtered multi-tone (CB-FMT) is a waveform that can be efficiently synthesized through a filter-bank in the frequency domain. Although the main principles have been already established, channel estimation has not been addressed yet. This is because of assuming that the existing techniques based on pilot symbol assisted modulation (PSAM...
Article
Full-text available
Under scenarios of high mobility, the traditional coherent demodulation schemes (CDS) have a limited performance, due to the fact that reference signals cannot effectively track the variations of the channel with an affordable overhead. As an alternative solution, non coherent demodulation schemes (NCDS) based on differential modulation have been p...
Conference Paper
Real-time communication schemes supporting fresh information are of major importance for vehicular networks. In this direction, the Age of Information (AoI) concept is a power-full tool to operate with. Current publications bring equal importance to the AoI of packets in spite of the common case of unequal channel capacity and source entropy betwee...
Article
We study the performance of linear zero-forcing (ZF) precoding in multiuser multiple-input single-output visible light communications (VLC) when we are able to select the receiving orientation angle (ROA) of each user. For radio-frequency communications, the non-line-of-sight rich scattering environment usually ensures the linear independence among...
Article
This paper considers short-term power constrained cell-free massive multiple-input multiple-output (MIMO) scenarios where a large set of multi-antenna access points (APs) provide service to a group of single-antenna mobile stations (MSs) on a spatially correlated multipath environment. Based on a probabilistic approach, the spatially correlated pro...
Conference Paper
The so-called 5G will revolutionize the way we live, and work. In order to demonstrate the profound changes, we can expect to experience within the next 5 to 10 years, we present use cases for the planned research within the TeamUp5G project. Some use cases are strongly linked to the network layer and aim at developing solutions capable of optimizi...
Article
Full-text available
The fifth-generation (5G) of cellular communications is expected to be deployed in the next years to support a wide range of services with different demands of peak data rates, latency and quality of experience (QoE). In this work, we propose a novel approach for radio network dimensioning (RND), named as Heuristic RND (HRND), which uses real open...
Article
Full-text available
Pilot symbol assisted modulation (PSAM) is widely used to obtain the channel state information (CSI) needed for coherent demodulation. It allows the density of pilot symbols to be dynamically chosen depending on the channel conditions. However, the insertion of pilots reduces the spectral efficiency, more severely when the channel is highly time-va...
Article
Full-text available
Orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-output (MIMO) are wireless radio technologies adopted by the new Fifth Generation (5G) of mobile communications. A very large number of antennas (massive MIMO) is used to perform the beam-forming of the transmitted signal, either to reduce the multi-user interference (MUI...
Chapter
Full-text available
Cellular communications have evolved to Fifth Generation (5G) to accommodate versatile use cases (UCs) requirements. These UCs are ensured to provide higher data rates, massive connection density and ultralow latencies into a new era of Internet of Things (IoT) and smart cities. ITU-R has classified UCs into three categories: Enhanced mobile broadb...
Article
Full-text available
In this paper, we consider parallel and sequential task offloading to multiple mobile edge computing servers. The task consists of a set of inter-dependent sub-tasks, which are scheduled to servers to minimize both offloading latency and failure probability. Two algorithms are proposed to solve the scheduling problem, which are based on genetic alg...
Chapter
Orthogonal frequency‐division multiplexing (OFDM) is one of the most well‐known multicarrier modulation (MCM) schemes. It has been adopted in several wideband digital communication systems and is the selected waveform for the New Radio (NR) in 5G. In this article, we provide a general overview of this MCM, describing the OFDM signal generation and...
Article
Full-text available
Presents information and current topics of interest to the global communications industry.
Article
In hybrid analog-digital schemes, proposed to reduce the number of RF chains especially at millimeter waves, the precoding at the transmitter and the combining at the receiver are split into digital and analog parts. We analyze the sensitivity of hybrid schemes to phase noise and channel estimation errors and we compare them to a full-digital appro...
Article
Full-text available
Visible light communications (VLC) are proposed for increasing the spectral efficiency and the number of devices served in indoor environments, while providing illumination through light emitting diodes (LED). For VLC, each optical access point (AP) provides a small and confined area of coverage. Since several sources of light are usually deployed...
Chapter
The 5G radio access network (RAN) brings new requirements, with higher spectral efficiency to accommodate the needs of emerging applications. In this context, massive multiple‐input multiple‐output (m‐MIMO) is becoming one of the key enabling technologies for 5G and beyond. However, the current communication technologies are based on coherent trans...
Chapter
The effect of phase noise in 5G is very relevant. With OFDM, correction schemes can combine phase noise reduction and channel estimation. In 5G, the use of multiple‐input‐multiple output requires the extension to MIMO‐OFDM, in particular using zero‐forcing (ZF) and maximum ratio transmission (MRT). The phase noise degradation shows a greater robust...
Article
Full-text available
VLC has emerged as a prominent technology to address the radio spectrum shortage. It is characterized by the unlicensed and unexploited high bandwidth, and provides the system with cost-effective advantages because of the dual-use of light bulbs for illumination and communication and the low complexity design. It is considered to be utilized in var...
Article
Full-text available
The irruption of the cell-free (CF) massive multiple-input multiple-output (MIMO) network topology has meant taking one step further the concept of massive MIMO as a means to provide uniform service in large coverage areas. A key property of massive MIMO networks is channel hardening, by which the channel becomes deterministic when the number of an...
Article
The application of non-orthogonal multiple access (NOMA) to downlink multi-user multiple-input single-output systems involves the design of a beamforming strategy in which the spatial dimension provided by each beam is shared among several users performing NOMA. This approach requires the management of both inter-cluster and intra-cluster interfere...
Conference Paper
The need to estimate a large number of channels in massive MIMO (mMIMO) has led to the proposal of non coherent (NC) detection, where the channel state information (CSI) is not necessary. In this paper, we discuss the tradeoff between NC designs based on phase-detection (PD) and those based on energy-detection (ED) for mMIMO in terms of performance...
Article
Various types of communication networks are constantly emerging to improve connectivity services and facilitate the interconnection of various types of devices. This involves the development of several technologies, such as device-to-device communications, wireless sensor networks and vehicular communications. The various services provided have het...
Article
Presents the President�s message for this issue of the publication.
Article
Full-text available
In this paper, a collision-free sequential task offloading scheme to multiple mobile-edge computing servers is proposed. The problem is formulated as a multi-objective optimization of latency and offloading failure probability. An exact solution technique is developed to obtain a benchmark optimal solution for the problem. A more computationally ef...
Preprint
Visible-light communication (VLC) has emerged as a prominent technology to address the radio spectrum shortage. It is characterized by the unlicensed and unexploited high bandwidth, and provides the system with cost-effective advantages because of the dual-use of light bulbs for illumination and communication and the low complexity design. It is co...
Conference Paper
IoT, Internet of Things is one of the most promising technologies of the fifth-generation (5G). The buzz is all about creating smart environments and getting every type of device connected to the internet. 5G will revolutionize the speed at which the data is transferred, and how much can be transferred at one time. Millimeterwave (mmWave) and massi...
Preprint
Various types of communication networks are constantly emerging to improve the connectivity services and facilitate the interconnection of various types of devices. This involves the development of several technologies, such as device-to-device communications, wireless sensor networks and vehicular communications. The various services provided have...
Conference Paper
Mobile operators have already started their 5G network deployment and next generation user terminals commercial release is planned for the upcoming months. Knowing the future network system performance and capabilities seem to be key in order to have proper planning strategies. In this paper we present some field test trials for the latest release...
Article
Full-text available
Superimposed Training (ST) is a semiblind channel estimation technique, proposed for orthogonal frequency division multiplexing (OFDM), where training sequences are added to data symbols, avoiding the use of dedicated pilot-subcarriers, and then increasing the available bandwidth compared to pilot symbol assisted modulation (PSAM). Filter bank mult...
Article
Presents information and current topics of interest to the global communications industry.