Miguel González-López

A Review on Internet of Things for Defense and Public Safety

The Internet of Things (IoT) is undeniably transforming the way that organizations communicate and organize everyday businesses and industrial procedures. Its adoption has proven well suited for sectors that manage a large number of assets and coordinate complex and distributed processes. This survey analyzes the great potential for applying IoT technologies (i.e., data-driven applications or embedded automation and intelligent adaptive systems) to revolutionize modern warfare and provide benefits similar to those in industry. It identifies scenarios where Defense and Public Safety (PS) could leverage better commercial IoT capabilities to deliver greater survivability to the warfighter or first responders, while reducing costs and increasing operation efficiency and effectiveness. This article reviews the main tactical requirements and the architecture, examining gaps and shortcomings in existing IoT systems across the military field and mission-critical scenarios. The review characterizes the open challenges for a broad deployment and presents a research roadmap for enabling an affordable IoT for defense and PS.

Serially-Concatenated Low-Density Generator Matrix (SCLDGM) Codes for Transmission Over AWGN and Rayleigh Fading Channels

Low density generator matrix (LDGM) codes are a particular class of low density parity check (LDPC) codes with very low encoding complexity. Single LDGM codes present high error-floors, which can be substantially reduced with the serial concatenation of two LDGM (SCLDGM) codes. We propose a technique to obtain good SCLDGM codes using extrinsic information transfer (EXIT) functions in a novel way. Although the optimization is performed for AWGN channels with binary signaling, the resulting codes are also optimal for AWGN and perfectly-interleaved Rayleigh fading channels with non-binary signaling and perfect CSI at reception, provided that Gray mapping is utilized. Optimized regular and irregular SCLDGM codes outperform heuristically-designed LDGM codes existing in the literature, and have a performance similar to or better than that of irregular repeat accumulate (IRA) codes.

Experimental Evaluation of Analog Joint Source-Channel Coding in Indoor Environments

Recently, analog joint source-channel coding has been proposed as a means of achieving near-optimum performance for high data rates with a very low complexity. However, no experimental evaluation showing the practical feasibility of this scheme has been performed to date. In this paper, we describe a software-defined radio implementation of an analog joint source-channel coded wireless transmission system. Experimental evaluation carried out in an indoor environment making use of a wireless testbed show that the performance perfectly matches that originally reported by simulations in additive white Gaussian noise channels for signal-to-noise ratio values below 20 dB.

Home Automation System Based on Intelligent Transducer Enablers

This paper presents a novel home automation system named HASITE (Home Automation System based on Intelligent Transducer Enablers), which has been specifically designed to identify and configure transducers easily and quickly. These features are especially useful in situations where many transducers are deployed, since their setup becomes a cumbersome task that consumes a significant amount of time and human resources. HASITE simplifies the deployment of a home automation system by using wireless networks and both self-configuration and self-registration protocols. Thanks to the application of these three elements, HASITE is able to add new transducers by just powering them up. According to the tests performed in different realistic scenarios, a transducer is ready to be used in less than 13 s. Moreover, all HASITE functionalities can be accessed through an API, which also allows for the integration of third-party systems. As an example, an Android application based on the API is presented. Remote users can use it to interact with transducers by just using a regular smartphone or a tablet.

Design of Serially-Concatenated LDGM Coded MIMO Systems

Serially-concatenated low-density generator matrix (SCLDGM) codes are an attractive scheme to approach the capacity of single input single output (SISO) channels due to the low computational cost of the encoding and decoding procedures. In this paper we investigate the design of SCLDGM codes for the spatial multiplexing over multiple input multiple output (MIMO) wireless communication channels. SCLDGM codes are constructed using an optimization procedure based on tracking the decoding behaviour of the sum-product algorithm (SPA) using extrinsic information transfer (EXIT) functions. We present results for different antenna configurations, showing that the optimized SCLDGM codes exhibit better performance than standard low density parity check (LDPC) codes with similar encoding complexity

Mobile WiMAX for vehicular applications: Performance evaluation and comparison against IEEE 802.11p/a

Vehicular communications have received a lot of attention in recent years due to the demand for applications to improve safety and travel comfort. Nowadays, IEEE 802.11p seems to be the best positioned standard for providing safety services. However, for non-safety services, which usually do not present tight time restrictions but require high data transfer rates, other wireless communication standards such as IEEE 802.16e (Mobile WiMAX) may exhibit better performance. In order to shed light on this question, we developed the physical (PHY) layer of a Mobile WiMAX software transceiver and measured its performance using a channel emulator implemented on an FPGA (Field-Programmable Gate Array) that recreates six different vehicular scenarios, including a highway, urban canyons and a suburban area. Furthermore, we have compared such performance with those obtained with IEEE 802.11p and IEEE 802.11a standards, concluding that, in most of the vehicular scenarios considered, the PHY-layer of Mobile WiMAX exhibits a superior performance. The performance results presented herein can also be used as the input for network simulators to carry out more accurate system-level simulations that should help in making a final decision on which standard should be used in each specific vehicular network.

Turbo aided maximum likelihood channel estimation for space-time coded systems

We propose a novel approach to estimating multiple-input-multiple-output (MIMO) channels in space-time coded systems. The channel is assumed to introduce dispersion in both the spatial and temporal dimensions. The channel estimator is obtained by applying the maximum likelihood principle, not only over a known pilot sequence, as in classical least-squares approaches, but also over all the symbols (both known and unknown) in a data frame. Since this results in an optimization problem without closed-form solution, we utilize an iterative method, the expectation-maximization (EM) algorithm, to calculate the solution. The resulting channel estimator is particularly suitable to be used in a turbo equalizing structure because it benefits from the a posteriori probabilities about the transmitted symbols computed at each decoding iteration of the turbo process.

FPGA-based vehicular channel emulator for real-time performance evaluation of IEEE 802.11p transceivers

IEEE 802.11p is one of the most promising future wireless standards due to the increasing demand of vehicular communication applications. At the time of writing, the document of the standard is in draft and much research is still required to study and improve the performance of transceivers in common vehicular scenarios. In this paper, we present a framework to evaluate the PHY layer of IEEE 802.11p systems in realistic situations. We detail the design and implementation of an FPGA-based real-time vehicular channel emulator. Contrarily to commercial emulators, ours is cheap, very flexible, and reconfigurable. We show its capabilities by evaluating performance in different high-speed scenarios. We also study the importance of coding and the benefits of using IEEE 802.11p instead of IEEE 802.11a in vehicular environments. Towards this aim, we developed a reference IEEE 802.11p PHY transceiver software model that can be taken as a convenient starting point for transceiver design.

FPGA-based vehicular channel emulator for evaluation of IEEE 802.11p transceivers

We present a hardware vehicular channel emulator aimed at assessing the performance of IEEE 802.11p transceivers in realistic scenarios. Contrarily to commercial emulators, which are usually very expensive and not quite flexible, we have developed an FPGA-based solution that is cheap, flexible and reconfigurable. In this paper we outline its design, implementation and basic operation. To show its capabilities, we present two examples of performance evaluation: we measure the bit error rate and packet error rate of an IEEE 802.11p system when performing transmissions between two vehicles that are approaching at high speeds in a highway and in an urban canyon.

A distributed multilayer architecture enabling end-user access to MIMO testbeds

We propose a distributed multilayer architecture that provides user access to a MIMO testbed at the convenient abstraction level for researchers. This novel architecture releases the user from the need of low-level programming, making the MIMO testbed accessible through high level software (i.e. Matlab or similar). The layers of this architecture are highly decoupled among them, allowing us to run each layer on a different PC. Also, each layer permits independent extension or customisation as needed, for example to implement new testbed features such as a feedback channel or to deploy multiuser MIMO scenarios.