In this paper, a novel double square slot antenna for 5G Small-Area Wireless Access Points (SAWAPs) at 3.6 GHz. The proposed antenna is specifically designed to enable 5G SA deployed in street furniture, such as street lampposts, utility poles or technical cabinets. Several design requirements have been particularly addressed, such as, reduced form factor (to be easily integrated in existing street furniture), operation in the 5G FR1 n78 frequency band with a bandwidth defined from 3.4 GHz to 3.8 GHz, while presenting an omnidirectional radiation pattern in the azimuth plane with at least 5dBi of gain. The proposed antenna layout is composed of two inset feed microstrip patches with both etched patch and ground plane, previously developed by the authors, disposed in the configuration of an array. An improved ground plane is employed to maximize the antenna bandwidth. The antenna optimisation is achieved with the aid of parametric simulations realised in CST MWS. After optimisation in CST MWS, the antenna designed in Rogers 4350B substrate, presents a final dimension of 130× 55× 1.6mm3, a bandwidth of 400 MHz, defined from 3.4 to 3.8 GHz, with an omnidirectional radiation pattern with a realised gain higher than 5 dBi in the entire bandwidth. The impact of employing the developed antenna in a modern style street lamppost is also presented.

In this paper, a 4D MIMO radar with 360° field of view is presented. After a brief description of the proposed architecture, using three millimeter wave 4D radio detection and ranging (Radar) sensors (Texas Instruments AWR1843), disposed in a equilateral triangular prism shape, this paper presents the first results on the implementation of a real-time and high resolution radar sensor with 360° of field of view. Experimental results obtained in a controlled environment, i.e. inside an anechoic chamber, are presented to validated the proposed concept. Successful target detection is achieved by multi-point point-cloud. The proposed radar architecture may be seen as an opportunity to augment and improve Advanced Driver Assistance Systems (ADAS) and Autonomous Driving Systems (ADS).

In this paper, we fill a void between information theoretic security and practical coding over the Gaussian wiretap channel using a three-stage encoder/decoder technique. Security is measured using Kullback-Leibler divergence and resolvability techniques along with a limited number of practical assumptions regarding the eavesdropper's decoder. The results specify a general coding recipe for obtaining both secure and reliable communications over the Gaussian wiretap channel, and one specific set of concatenated codes is presented as a test case for the sake of providing simulation-based evaluation of security and reliability over the network. It is shown that there exists a threshold in signal-to-noise ratio (SNR) over a Gaussian channel, such that receivers experiencing SNR below the threshold have no practical hope of receiving information about the message when the three-stage coding technique is applied. Results further indicate that the two innermost encoding stages successfully approximate a binary symmetric channel, allowing the outermost encoding stage (e.g., a wiretap code) to focus solely on secrecy coding over this approximated channel.

This paper presents a testbed implementation and evaluation of coding for secrecy schemes in a real environment through software defined radio platforms. These coding schemes rely on interleaving and scrambling with randomly generated keys to shuffle information before transmission. These keys are then encoded jointly with data and then hidden (erased) before transmission, thus only being retrievable through parity information resulting from encoded data. An advantage of the legitimate receiver (e.g. a better signal-to-noise ratio) on the reception of those keys provides the means to achieve secrecy against an adversary eavesdropper. Through this testbed implementation, we show the practical feasibility of coding for secrecy schemes in real-world environments, unveiling the usefulness of interleaving and scrambling with a hidden key to reduce the required advantage over an eavesdropper. We further describe and present solutions to a set of issues that appear when doing practical implementations of security schemes in software defined radio platforms.

The growing progress in wireless communication services lead to a demand in high data rates, spectral efficiency and flexibility requirements. The recently proposed Block-Windowed Burst Orthogonal Frequency Division Multiplexing (BWB-OFDM) transceiver proved to be a reliable alternative scheme to face these current demands. BWB-OFDM employs smoother, non- rectangular windows, allowing a power spectral density similar to the filtered OFDM approach; also, it packs together several OFDM symbols, with the addition of a sole zero- padding to accommodate the multipath channel's propagation delay. This means better overall power and spectral efficiencies. Nevertheless, the system has the same drawback of OFDM when transmitting over hostile channel conditions, such as deep fading in time-dispersive channels. To overcome this problem, a new Time-Interleaved BWB- OFDM (TIBWB- OFDM) transceiver is proposed. This scheme employs interleaving on the time-samples of each BWB- OFDM block, thus creating a sort of diversity at the frequency domain, aiming to preserve the data symbols severely corrupted by the channel's deep fades. The new TIBWB-OFDM transceiver presents considerable power gains relatively to the BWB-OFDM,while maintaining their spectral efficiency.

This paper proposes a framework for extending the applicability of the discrete RET (dRET) model to accommodate radiowave scattering from tree trunks, particularly in microcell urban mobile scenarios, at micro- and millimetre wave frequencies. This framework aims to provide accurate modelling of the signal emanated inside and around isolated blocks of tree trunks, for instances, in raised canopy forests or in urban street canyons like scenarios. Model validation against measurement results inside an anechoic chamber for a double line of regularly spaced metallic and dielectric trunks at 18.8 GHz, as well as recommendations for a more encompassing model, are presented.

This paper presents a method to improve extraction theradiativeenergytransfer(RET) theory input parameters for application in vegetation attenuation modelling. The input parameters for this model, which are extracted from specific measurement data, are normally influenced by the radiation pattern of the receiver antenna. A new method to improve the accuracy of the scattering function parameters obtained from measurements is presented. This method is based on the inverse convolution, allowing mitigation of the receiver antenna radiation pattern effects on the extracted parameters. The method was tested with measurements at 20 and 40 GHz using several different receiver antennas.

This paper presents a radiowave propagation model for inhomogeneous forests based on the radiative energy transfer theory (RET). This model, which is a discretised version of the RET, is able to simulate the behaviour of radiowaves inside a forest which contains various kinds of vegetation and free space gaps. To do this, the forest is divided into non-overlapping square cells, each one with different propagation characteristics. The propagation properties of each cell rely on specific propagation parameters, which are extracted from the vegetation using an appropriate practical method which is also described in this paper. The model performance is assessed through comparison with directional spectrum measurements carried out in an isolated inhomogeneous forest at 11.2 and 40 GHz.

A method based on the radiative energy transfer theory (RET) to estimate the scattered signals from isolated groups of trees is presented. The proposed method consists of measuring the reradiation function of each tree in the group and subsequently uses these in a discrete algorithm to estimate the overall reradiation at any location within a forest scenario. The estimated scattering is compared with measurements performed inside an anechoic chamber on two tree species at 20 and 62.4 GHz.