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In this paper, the wideband characterization of the propagation channel in circular metallic indoor environments is addressed, regarding Body Area Networks and 5G small cells, an analytical model for the dependence of the mean delay and the average delay spread on the circle radius, the working frequency and the distance between the transmitter and the receiver being proposed. The derivation of the model is initially done analytically, based on optical physics, after which simulation results allow to obtain the values of the coefficients. The simulator was previously assessed with measurements at 2.45 GHz in a passenger ferry room with a circular shape. For a random positioning of the transmitter and the receiver, and a given distance between them, it is observed that the mean delay and the delay spread increase linearly with the radius; furthermore, the mean delay increases quadratically with the distance, while the delay spread has a concave parabolic behavior, with the maximum being at a distance equal to the radius. In a practical case, regarding the positioning of an Access Point inside the room, it is recommended that it is done at the circle center, in order to reduce delay spread.

In this paper, Body-to-Body communications in indoor and outdoor environments for different on-body antenna configurations and different mobility scenarios were studied, based on system loss measurements at 2.45 GHz. The main objective is to properly characterise the influence of the Transmitter-Receiver configuration on system loss and fast fading behaviour, the latter being modelled by the Rice Distribution. Globally, it is observed that there is no significant difference on the measured average system loss between indoor and outdoor environments, but a strong dependence is seen on the configuration of the antennas and on the mobility scenario. Concerning the Rice Factor, as expected, higher values were obtained in outdoor environments, due to the lower level of multipath, the difference to the indoor case being below 4 dB, depending on the mobility environment and on the positioning of the antennas.

A fast fading analysis for Body Area Networks operating at 2.45 GHz in cylindrical rooms with metallic walls is presented in the paper. A model was developed, based on geometrical ray bouncing. By using an empirically validated simulator, it is shown that it is enough to analyse up to 2nd order reflections. Additionally, it is shown that the normalised radius (to the wavelength) of the cylindrical room does not have a significant influence on fast fading characteristics. The obtained values for the Rice factor, being negative or very close to 0 dB, show that in this kind of environments fast fading can be characterised by the Rayleigh Distribution.

In this paper, an analytical model for slow and fast fading effects in maritime container terminals is derived, from fitting distributions to the results of measurements performed in an actual operational environment. The proposed model is composed of a set of equations, enabling to evaluate fading statistical distribution parameters for different system and environments conditions, as a function of frequency, base station antenna height, and average height of container stacks in a deepwater container terminal. The model's coefficients were obtained from a multivariate linear regression of the fitted distributions parameters, allowing to evaluate the different statistical distribution parameters with a negligible mean error and a standard deviation of the error less than 0.65 dB. It is observed that a good fitting is obtained for slow fading with the Lognormal Distribution, the standard deviation ranging in [1.40, 4.81] dB, while fast fading is well modeled by the Nakagami Distribution with the standard deviation ranging in [0.43, 1.26]. Hence, in a conservative perspective, values of 5 and 1.3 dB are proposed to characterize slow and fast fading, respectively.

Future networks will be composed of a network of networks, consisting of many multiple-access technologies, multiple bands and widely varying coverage areas, all self-organised and optimised, with seamless roaming among different systems. The Electromagnetic Field (EMF) exposure in this type of heterogeneous networks involves several aspects that need to be carefully addressed. In this chapter, an overview of the current methods to assess EMF levels in the 0.4-6 GHz band is presented. Different methods used to assess exposure in uplink (UL) and downlink (DL) scenarios are detailed, the impact of body shadowing on wearable exposimeter EMF measurements is assessed and the global exposure in heterogeneous networks composed of Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), Long-Term Evolution (LTE) and Wi-Fi systems, in different scenarios, varying usage, mobility and number of users, is evaluated.

Network virtualization covers aspects like resource virtualization and slicing. The virtualization of the physical resources consists of implementing multiple instances of a required logical resource on a single machine/node within the same or different set of physical resources allocated to the Virtual Network (VNet), the slice. Sharing radio resources on multiple access schemes has been intensively investigated for wireless systems concerning the separation of the radio links for different end-users of the same system. This chapter discusses the relevant aspects of radio resources management (RRM) and cooperative radio resources management (CoRRM) and radio resource sharing and wireless-virtualization-related work. It presents the network architecture, the model description, the strategies and algorithms for VNet radio resource allocation. The chapter also presents the results for Average Cluster Data Rate and Average Cluster Utilization. Regarding the Average Cluster Serving Data Rate, it is observed that it decreases slightly with the number of GRT virtual base stations (VBSs).

In this paper a detailed analysis of slow and fast fading effects in container terminal environments is presented, fading distribution parameters are evaluated and an analytical model is proposed. The model is composed of a set of analytical equations allowing to evaluate fading statistical distribution parameters for different system and environments conditions. Globally, it is observed that for slow fading a good fitting is obtained with the Lognormal distribution. Values of μ L and σ L ranges from −1.95 to −1.18 dB and 2.45 to 3.22 dB, respectively. Fast fading effects are well modelled by Rayleigh, Rice or Nakagami distributions with the later one being the more appropriate. The best fit was obtained with the Nakagami distribution with shape and scale parameters, μ N and Ω N , ranging from 0.79 to 1.23 and 2.52 to 3.58, respectively.

The goal of the European ICT Project EARTH is to enhance energy efficiency of current LTE cellular networks by 50 percent, enabling operators to provide more extensive coverage, namely to less densely populated areas, while ensuring high levels of efficiency, hence, reducing the carbon footprint. In order to achieve this objective, different strategies, at different levels, are being addressed. Energy efficient transmission techniques for LTE, proposed within the framework of EARTH, are addressed and discussed, with an emphasis on beamforming and MIMO. It is concluded that the strategic objective of EARTH is achievable. Combined MIMO mode selection, resource allocation, scheduling and precoding strategies will allow an energy consumption reduction of more than 50 percent in macro-cells. A reduction in MIMO power consumption of 91.7 percent (factor of 12) can be achieved in pico-cells.

The use of wearable devices, like smartwatches and smartglasses, with wireless communication capabilities are now becoming common. The use of such devices, radiating electromagnetic waves close to the human body, is also becoming a matter of concern. The SAR assessment of Google Glasses for 0.9 GHz, 1.94 GHz, 2.43 GHz and 2.6 GHz bands, corresponding to cellular (GSM, UMTS and LTE) and wireless (Wi-Fi), is presented. The assessment scenario is presented, and the simulations methodology is described. From simulations results, one concludes that the maximum recommended SAR value for the human head is only exceeded in the 0.9 GHz (GSM) band. For Wi-Fi, UMTS and LTE, there are no problems of exposure, since the maximum radiated power that fulfils SAR requirements is above the maximum power that a mobile terminal can radiate, according to the standards.

This paper addresses the virtualisation of wireless access in order to provide the required capacity (data rate) to a Virtual Base Station (VBS). The approach is based on a Virtual Radio Resource Allocation algorithm, OnDemandVRRA, which manages the allocation of the physical radio resources to VBSs' end-users, in order to follow the contract and maintaining isolation among VBSs, according to the type of guarantees of the VBSs, the amount of contracted capacity, and VBSs' utilisation. Taking the variability of the wireless medium into account, the algorithm continuously influences the RRM mechanisms, namely admission control and MAC scheduling, to be aware of the VBSs' state relative to the service level agreement, in order to compensate for this variability. The algorithm has been tested to evaluate its behaviour, concerning the amount of VBSs created over a given geographical area served by a set of base stations. It can be concluded that changing the quantity of created VBSs as well as the contracted data rate in the cluster, GRT VBSs get their minimum contracted data rate. It is also verified that the best Radio resource Unit (RU) efficiency is achieved when the strategy for the overall capacity provision is to limit the capacity contracted by GRT VNets, overbooking the capacity contracted by BE VNets. In this case, the RU efficiency increases 30% comparing to the situation where the overbooking is done by GRT VBSs.

In future virtual network (VNet) environments, where heterogeneous networks will coexist and new business roles and models are expected, VNets cooperation for radio resource management is one of the key issues in order to achieve an efficient integration of different wireless technologies, while providing the required quality of service. In this paper, an algorithm for Virtual Radio Resource Allocation (VRRA), called OnDemandVRRA, in multiple and heterogeneous virtual networks environment is proposed and discussed. OnDemandVRRA manages the radio resources allocation to the VNets in order to satisfy the VNet contracted capacity. The algorithm has been assessed for two different Virtual scenarios by comparison with a Standard one, in which several network operators have their own networks, each being shared among several mobile virtual network operators. It is shown that the application of OnDemandVRRA to virtualise the wireless access allows achieving better performance from a cluster of several base stations of different radio access technologies, supporting the provision of the contracted capacity for guaranteed VNets, i.e., VNets with a minimum contracted capacity. Globally, it is observed that Virtual scenarios perform better than the Standard one, as the cluster serving data rate may increase by approximately 46 %, if minimum and reference values for the VNet's contracted capacity have been set. Moreover, in this case, end-users performing best-effort services are served with an average data rate approximately three times higher than in other scenarios, where the reference data rate for the VNet providing these services is not set.

In this paper a time-domain technique for wideband fading depth evaluation, is proposed, which is applicable to both Line-of-Sight and Non-Line-of-Sight cases, and the probability functions of the wideband received power are derived, contributing for filling in the gap of short-term fading characterisation in wideband systems. Application examples for different systems, namely GSM, UMTS and HIPERLAN/2, working in different standard reference environments, are shown. As expected, it is observed that Rayleigh and Rice distributions are appropriate for evaluating the fading margins for GSM in some environments; nevertheless, for UMTS and HIPERLAN/2, fading margins are usually well below the ones obtained from considering these narrowband distributions, the differences reaching up to around 10 and 13 dB, respectively. A simple relationship between the physical and the geometrical environment properties, and the rms delay spread of the propagation channel is also proposed, establishing a relationship between two models independently derived by different authors. Using the proposed relationship, fading depth results from the proposed time-domain technique are compared with the ones for an environment-geometry based one, and a good agreement is verified. The difference in fading depth between both approaches is roughly below 2 dB.

A simple and computationally inexpensive analytical approach is proposed for the evaluation of the dependence of short-term fading depth on system bandwidth and environmental characteristics. The approach, accounting for the maximum difference in propagation path length and having the Rice factor as a parameter, is derived by fitting simulated data from a model in the literature. Application examples are presented for GSM, UMTS, HIPERLAN, and mobile broadband systems (MBS), giving some insight into the fading depth observed under different conditions with regard to system bandwidth and environmental characteristics. Macro-, micro-, and picocell environments are considered. In the microcellular environment, the fading depth experienced by UMTS is below the one for GSM by 0.1 to 5.5 dB, while in the picocellular one, the difference between GSM and UMTS is not significant, being almost independent of environment characteristics. When considering HIPERLAN or systems with larger bandwidths, the fading depth, both in micro and picocellular environments, is smaller than the one verified by UMTS; however, there is an increased dependence on environmental characteristics. In the macrocellular environment, the fading depth experienced by UMTS is about 6 to 11 dB below the one for GSM. Hence, different short-term fading margins should be considered for each system and working environment.

Trabalho apresentado em 40th Annual Conference of the IEEE Industrial Electronics Society, 29 outubro/ 1 novembro 2014, Dallas, TX, USA. In this paper a wireless home automation system is presented. The proposed system allows controlling devices in a home environment by using a simple Bluetooth equipped mobile phone. The mobile phone communicates with a main Bluetooth/ZigBee module that communicates with the different ZigBee modules acting as the coordinator of the ZigBee network established between all nodes where electrical devices are connected. The identification of each device is made through DomoML strings by using the KNX home automation standard protocol. N/A

This paper addresses wireless capacity sharing by means of wireless access virtualisation, allowing to provide the required capacity to a set of differentiated Virtual Base Stations (VBSs) instantiated within a geographical area. An algorithm to manage the allocation of radio resources from different radio access technologies to the VBSs, OnDemandVRRA, is proposed. The main target is to provide the required capacity to the VBSs, according to the type of guarantees and their usage, maintaining isolation among them. Taking into account the variability of the wireless channel, the proposed algorithm continuously influences Radio Resource Management, namely admission control and MAC scheduling, to be aware of the VBSs' state relative to the service level agreement. The algorithm has been tested to evaluate its behaviour concerning the existence of a different mixing of VBSs' types in the physical cluster. From simulation results, it can be concluded that, independently of the percentage of each VBSs type instantiated in the physical cluster, just minor differences are perceived for the metrics being used, e.g., the maximum deviation of the Average Cluster Serving Data Rate as a function of the number of guaranteed VBSs is about 0.7%.

This paper addresses the virtualisation of wireless access in order to provide the required capacity (data rate) to a set of Virtual Base Stations (VBSs). The approach is based on a Virtual Radio Resource Allocation algorithm, OnDemandVRRA, which manages the allocation of the physical radio resources to the VBSs, in order to follow the contract and maintaining isolation among the VBSs, according to the type of guarantees of the VBSs, the amount of contracted capacity, and the VBSs' utilisation. Taking the variability of the wireless medium into account, the algorithm continuously influences RRM mechanisms, namely admission control and MAC scheduling, to be aware of the VBSs' state relative to the service level agreement, in order to compensate for this variability. The algorithm has been tested to evaluate its behaviour, concerning the amount of virtual contracted capacity versus the physical one. From simulation results, it can be concluded that the total capacity contracted for guaranteed VBSs should be limited according to the average capacity provided by the physical set of serving base stations. As an example, although the guaranteed VBS contracted capacity is always achieved, for the case where the guaranteed VBS contracted capacity is about 85% of the average cluster capacity, the cluster serving data rate decreases about 20% relative to the maximum achieved for the Best Effort Overbooking use case.

The actual internet traffic growth is challenging the sustainability of mobile networks, therefore, the energy efficiency of the mobile communication infrastructure becomes a topic of particular relevance. Decreasing CO2 emissions and energy demands while expanding the mobile infrastructure to satisfy traffic demands is essential. In this paper the energy efficient use of beamforming techniques and active antennas, in which an advanced antenna is utilized to direct the transmitted signal in a narrow direction, is evaluated. Slow beamforming based on reconfigurable antennas, exploits medium/long term variations of traffic in order to save energy. Fast beamforming, on the contrary, is immediately following the traffic distribution and can even allow saving more energy. From simulations it is observed that, when compared to existing state-of-art bases base stations, in a dense urban environment reconfigurable beamforming allows a maximum gain of about 8%. Adaptive beamforming, allows an additional consumed power reduction of up to 40%. Hence, the overall power consumption reduction that can be achieved by combining these techniques can be as high as 50%.

With the increase of mobile network utilisation, the virtualisation of wireless resources becomes an important issue in the overall Virtual Networks (VNets) process. In this paper, the On Demand Virtual Network Radio Resource Allocation (OnDemand VRRA) mechanism is proposed to take advantage of the set of shared resources available within a cluster of wireless resources from different Radio Access Technologies (RATs) for wireless virtualisation. Optimising resource utilisation satisfying the VNet contracted capacity is its main objective. Furthermore, the mechanism is modelled according to the Open Connectivity Services (OConS) architecture, in order to demonstrate the advantages of its use within the OConS framework. Simulation results show that the introduction of OnDemand VRRA allows supporting the minimum bandwidth requirement in a wireless cluster, composed of several physical base stations from different RATs. The percentage of operation out of contract (i.e., below the virtual operator’s contracted capacity) for a VNet with guaranteed minimum service is zero for a number of end users in the VNet up to 80% of the total, which is higher than in other circumstances. One also observes that VNets providing guaranteed services can achieve the contracted data rate independently of the number of end users in other VNets.

Current 3GPP specifications for LTE include the use of MIMO as a key technology. MIMO can be seen from two different perspectives: if increased data rates are targeted, for a given value of SNR, one gets improved data transmission; however, from an energy efficiency viewpoint, lower values of SNR are needed for the same reference data rate, therefore, allowing the reduction of the transmitted power, while providing the same data rate as the one for SISO. In this paper, a framework for evaluating the possible benefit of using MIMO instead of SISO, from the expected SNR improvement viewpoint is proposed, and results for different environments are presented and discussed. The proposed evaluation methodology allows one to properly assess the expected benefits of MIMO, therefore, providing guidelines to enable a proper SISO/MIMO mode selection according to the required service data rate. The analysis being presented is based on existing 3GPP models for data rate versus SNR in LTE. Simulation results for the ETU70 3GPP channel model are provided. It is observed that, for given reference data rates, significant SNR improvements can be obtained. Maximum values of 7.1, 15.7 and 18.0 dB SNR reduction are obtained for 2×2, 4×4 and 8×8 MIMO configurations, compared to the SISO case, therefore, allowing a significant reduction of the transmitted power, while providing the same target data rate as the one for SISO.

In this article, physical layer awareness inaccess, core, and metro networks is addressed,and a Physical Layer Aware Network Architec-ture Framework for the Future Internet is pre-sented and discussed, as proposed within theframework of the European ICT Project4WARD. Current limitations and shortcomingsof the Internet architecture are driving researchtrends at a global scale toward a novel, secure,and flexible architecture. This Future Internetarchitecture must allow for the co-existence andcooperation of multiple networks on commonplatforms, through the virtualization of networkresources. Possible solutions embrace a fullrange of technologies, from fiber backbones towireless access networks. The virtualization ofphysical networking resources will enhance thepossibility of handling different profiles, whileproviding the impression of mutual isolation.This abstraction strategy implies the use of wellelaborated mechanisms in order to deal withchannel impairments and requirements, in bothwireless (access) and optical (core) environ-ments. info:eu-repo/semantics/publishedVersion

Self-organization is a key issue in Wireless Sensor Networks being a common answer to optimize the operation of network nodes. The choice for a particular structure has been handled through empirical or intuitive approaches rather than being based on studies that proved the suitability to each scenario. First, several typical application scenarios found in Wireless Sensor Networks are presented and extrapolated to a set of simulated ones. Second, a comparative evaluation between several self-organized structures used in Wireless Sensor Networks in terms of energy efficiency and network throughput is presented. From simulation results, one concludes that the multi-sink solution presents lower energy consumption and lower packet loss ratio, enhancing network lifetime while improving network performance.

The use of directional antennas at the mobile terminal or the base station, and its influence on the observed values of short-term fading depth, is addressed. This influence is modelled through the variation of the Rice factor and the maximum difference in propagation path length among different arriving components, relative to the case when omnidirectional antennas are used. Expressions for the dependence of these parameters on the antenna beamwidth, for different statistical distributions for the angle-of-arrival of arriving waves, and different types of antennas are presented. For illustration, results on the fading depth observed by UMTS and HIPERLAN/2 in different environments are presented and discussed. Globally, when using directional antennas, fading depth reduction is observed in micro-cellular environments; in macro- and pico-cellular ones, fading depth degradation can occur depending on the environment and system characteristics.

Existing systems, eg., UMTS and HIPERLAN, and others to appear in the future, are wideband ones; hence, the observed short-term fading depths are usually smaller than the ones obtained from the Rayleigh or Ricean distributions. Overestimating short-term fading margins, by considering those distributions, leads to shorter cells, or to higher transmitting powers, thus, higher interference. In this paper, one proposes a simple relationship between the physical and the geometrical environment properties, and the rms delay spread of the propagation channel, therefore, allowing one to use different model for evaluating the fading depth in a given environment. Using the proposed relationship, fading depth results from two different models are compared, and a good agreement is verified. Furthermore, since the presented models account for the influence of system bandwidth, hence, providing more accurate fading margins (e.g., the fading margins for UMTS are usually 2 to 10 dB below the ones obtained from Rayleigh or Ricean distributions), the proposed approach allows a better power budget evaluation, enabling the optimisation of existing networks, and better and less costly radio network planning of future ones.

A technique for fading depth characterisation in wideband mobile communications systems is described. The approach, based on the eigenvalue decomposition technique, allows deriving the cumulative distribution functions of the received power for Rayleigh and Ricean fading channels. Application examples for different systems, namely GSM, UNITS, HIPERLAN and MBS, working within different environments, as proposed by standard-setting bodies, are shown in detail, and the results are discussed, giving a general insight into the fading depth behaviour. In the considered environments, the fading depth experienced by GSM is between 9.4 and 18.4 dB. The fading depth observed by UNITS is below the one for GSM by 2.1 to 10.3 dB. Regarding HIPERLAN, the observed fading depth is 2.6 to 4.9 dB below the one for UNITS. MBS experiences fading depths that are usually below 9.7 dB (a worst case of 10.6 dB is observed in city streets under NLoS). Since the observed fading depth depends on the system and environment characteristics, different fading margins should be considered for each system and working environment.