The electronically steerable parasitic array radiator antenna for wireless communications : signal processing and emerging techniques

Smart antenna technology is expected to play an important role in future wireless communication networks in order to use the spectrum efficiently, improve the quality of service, reduce the costs of establishing new wireless paradigms and reduce the energy consumption in wireless networks. Generally, smart antennas exploit multiple widely spaced active elements, which are connected to separate radio frequency (RF) chains. Therefore, they are only applicable to base stations (BSs) and access points, by contrast with modern compact wireless terminals with constraints on size, power and complexity. This dissertation considers an alternative smart antenna system the electronically steerable parasitic array radiator (ESPAR) which uses only a single RF chain, coupled with multiple parasitic elements. The ESPAR antenna is of significant interest because of its flexibility in beamforming by tuning a number of easy-to-implement reactance loads connected to parasitic elements; however, parasitic elements require no expensive RF circuits. This work concentrates on the study of the ESPAR antenna for compact transceivers in order to achieve some emerging techniques in wireless communications. The work begins by presenting the work principle and modeling of the ESPAR antenna and describes the reactance-domain signal processing that is suited to the single active antenna array, which are fundamental factors throughout this thesis. The major contribution in this chapter is the adaptive beamforming method based on the ESPAR antenna. In order to achieve fast convergent beamforming for the ESPAR antenna, a modified minimum variance distortionless response (MVDR) beamfomer is proposed. With reactance-domain signal processing, the ESPAR array obtains a correlation matrix of receive signals as the input to the MVDR optimization problem. To design a set of feasible reactance loads for a desired beampattern, the MVDR optimization problem is reformulated as a convex optimization problem constraining an optimized weight vector close to a feasible solution. Finally, the necessary reactance loads are optimized by iterating the convex problem and a simple projector. In addition, the generic algorithm-based beamforming method has also studied for the ESPAR antenna. Blind interference alignment (BIA) is a promising technique for providing an optimal degree of freedom in a multi-user, multiple-inputsingle-output broadcast channel, without the requirements of channel state information at the transmitters. Its key is antenna mode switching at the receive antenna. The ESPAR antenna is able to provide a practical solution to beampattern switching (one kind of antenna mode switching) for the implementation of BIA. In this chapter, three beamforming methods are proposed for providing the required number of beampatterns that are exploited across one super symbol for creating the channel fluctuation patterns seen by receivers. These manually created channel fluctuation patterns are jointly combined with the designed spacetime precoding in order to align the inter-user interference. Furthermore, the directional beampatterns designed in the ESPAR antenna are demonstrated to improve the performance of BIA by alleviating the noise amplification. The ESPAR antenna is studied as the solution to interference mitigation in small cell networks. Specifically, ESPARs analog beamforming presented in the previous chapter is exploited to suppress inter-cell interference for the system scenario, scheduling only one user to be served by each small BS at a single time. In addition, the ESPAR-based BIA is employed to mitigate both inter-cell and intracell interference for the system scenario, scheduling a small number of users to be simultaneously served by each small BS for a single time. In the cognitive radio (CR) paradigm, the ESPAR antenna is employed for spatial spectrum sensing in order to utilize the new angle dimension in the spectrum space besides the conventional frequency, time and space dimensions. The twostage spatial spectrum sensing method is proposed based on the ESPAR antenna being targeted at identifying white spectrum space, including the new angle dimension. At the first stage, the occupancy of a specific frequency band is detected by conventional spectrum-sensing methods, including energy detector and eigenvalue-based methods implemented with the switched-beam ESPAR antenna. With the presence of primary users, their directions are estimated at the second stage, by high-resolution angle-of-arrival (AoA) estimation algorithms. Specifically, the compressive sensing technology has been studied for AoA detection with the ESPAR antenna, which is demonstrated to provide high-resolution estimation results and even to outperform the reactance-domain multiple signal classification

Multiband Patch Antenna for Femtocell Application

A microstrip patch antenna for multiple LTE (long term evaluation) frequency bands for femtocell application is proposed in this paper. Distributed antenna solution (DAS) has been introduced in cellular network to achieve homogenous indoor coverage. Femtocell is the latest extension to these solutions. It is a smart solution to both coverage and capacity scales. Femtocell operation in LTE band is occupied by higher frequency bands. For multiband femtocell application, miniature antenna design is quite essential. The antenna proposed here is composed of basic monopole structure with two parasitic elements at both sides of the active element. A rectangular slot is introduced at the ground plane of the proposed antenna. The antenna is designed using ElnoS HK light CCL substrate material of relative permittivity of 9.4, dielectric loss-tangent of 0.003 and thickness of 3 mm. The S11 response of the antenna is shown to have a bandwidth of 1.01 GHz starting from 1.79 GHz to 2.8 GHz. The characteristics of the antenna are analysed using Ansoft HFSS software

Performance analysis of cellular and ad-hoc sensor networks : theory and applications

Fifth-generation (5G) mobile networks have three main goals namely enhanced mobile broadband (eMBB), massive machine-type communication (mMTC) and ultra-reliable low latency communication (URLLC). The performance measures associated with these goals are high peak throughput, high spectral efficiency, high capacity and mobility. Moreover, achieving ubiquitous coverage, network and device energy efficiency, ultra-high reliability and ultra-low latency are associated with the performance of 5G mobile networks. One of the challenges that arises during the analysis of these networks is the randomness of the number of nodes and their locations. Randomness is an inherent property of network topologies and could occur due to communication outage, node failure, blockage or mobility of the communication nodes. One of the tools that enable analysis of such random networks is stochastic geometry, including the point process theory. The stochastic geometry and Poisson point theory allow us to build upon tractable models and study the random networks, which is the main focus of this dissertation. In particular, we focus on the performance analysis of cellular heterogeneous networks (HetNet) and ad-hoc sensor networks. We derive closed-forms and easy-to-use expressions, characterising some of the crucial performance metrics of these networks. First, as a HetNet example, we consider a three-tier hybrid network, where microwave (µWave) links are used for the first two tiers and millimetre wave (mmWave) links for the last tier. Since HetNets are considered as interference-limited networks, therefore, we also propose to improve the coverage in HetNet by deploying directional antennas to mitigate interference. Moreover, we propose an optimisation framework for the overall area spectral and energy efficiency concerning the optimal signal-to-interference ratio (SIR) threshold required for µWave and mmWave links. Results indicate that for the µWave tiers (wireless backhaul) the optimal SIR threshold required depends only on the path-loss exponent and that for the mmWave tier depends on the area of line-of-sight (LOS) region. Furthermore, we consider the average rate under coverage and show that the area spectral and energy efficiency are strictly decreasing functions with respect to the SIR threshold. Second, in ad-hoc sensor networks, coverage probability is usually defined according to a fixed detection range ignoring interference and propagation effects. Hence, we define the coverage probability in terms of the probability of detection for localisability. To this end, we provide an analysis for the detection probability and S-Localisability probability, i.e. the probability that at least S sensors may successfully participate in the localisation procedure, according to the propagation effects such as path-loss and small-scale fading. Moreover, we analyse the effect of the number of sensors S on node localisation and compare different range based localisation algorithms

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Energy sustainable paradigms and methods for future mobile networks: A survey

In this survey, we discuss the role of energy in the design of future mobile networks and, in particular, we advocate and elaborate on the use of energy harvesting (EH) hardware as a means to decrease the environmental footprint of 5G technology. To take full advantage of the harvested (renewable) energy, while still meeting the quality of service required by dense 5G deployments, suitable management techniques are here reviewed, highlighting the open issues that are still to be solved to provide eco-friendly and cost-effective mobile architectures. Several solutions have recently been proposed to tackle capacity, coverage and efficiency problems, including: C-RAN, Software Defined Networking (SDN) and fog computing, among others. However, these are not explicitly tailored to increase the energy efficiency of networks featuring renewable energy sources, and have the following limitations: (i) their energy savings are in many cases still insufficient and (ii) they do not consider network elements possessing energy harvesting capabilities. In this paper, we systematically review existing energy sustainable paradigms and methods to address points (i) and (ii), discussing how these can be exploited to obtain highly efficient, energy self-sufficient and high capacity networks. Several open issues have emerged from our review, ranging from the need for accurate energy, transmission and consumption models, to the lack of accurate data traffic profiles, to the use of power transfer, energy cooperation and energy trading techniques. These challenges are here discussed along with some research directions to follow for achieving sustainable 5G systems.Comment: Accepted by Elsevier Computer Communications, 21 pages, 9 figure

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

System Level Analysis And Design For Wireless Inter-Chip Interconnection Communication Systems By Applying Advanced Wireless Communication Technologies

As the dramatic development of high speed integrated circuits has progressed, the 60 GHz silicon technology has been introduced to enable much faster computer systems and their corresponding applications. However, when signals are propagating at 60 GHz or higher frequencies on a PCB (Printed Circuit Board), the crosstalk among signal buses and devices, trace losses, and introduced parasitic capacitance and inductance between high density traces, become significant and may be severe enough such that the inter-chip communications will not be able to meet computer system signal specifications. High speed circuit signal integrity researchers in both electronic industries and academia have explored various methodologies to resolve these high frequency issues. Moreover, Intel is introducing Ultra Path Interconnect (UPI) for multi-core server systems, which demands more than 2.44 Tbps data rate between two CPUs, and 1.5 Tbps data rate for PCIe channel operation. Recently, the concept of the wireless inter/intra-chip interconnection (WIIC) technology was introduced [19, 23] for solving high frequency signal integrity issues. Here this dissertation mainly focuses on the inter-chip case while still using the WIIC designation for generality. Various WIIC technologies have been presented in the literature, which have focused on the investigations on Ultra Wide-Band (UWB), propagation channels, modulations, antennas, and power controls and interference. However, not much research has focused on a system level design, which includes the lowest two layers of the communication protocol in a WIIC system, namely, the physical, and data link layers. Also, the previously published literature has rarely reached the data rate at 100 Gbps or higher, and none of the prior research has obtained a spectrum utilization ratio of 4 bit/Hz or greater. In addition, currently existing research has not fully taken advantage of advanced and matured wireless communication technologies such as Orthogonal Frequency Division Multiplexing (OFDM), high order modulation, and Multiple-Input/Multiple-Output (MIMO) systems for increasing data rates and improving reliability, although the use of UWB [29], conventional FDMA or TDMA [39], and binary modulations including Binary Phase Shift Keying (BPSK) [22], On-Off Keying (OOK) [31], and Amplitude Shift Keying (ASK) [35] have been studied in previous research. In this dissertation, a complete WIIC system and a representative WIIC channel model have been developed by taking full advantages of advanced wireless communication techniques. First, this research has analyzed the potential of higher-order modulation, error correction, OFDM, and channel coding to the WIIC setting. Although MIMO, interleaving and scrambling are also analyzed but not included in the current version of the proposed WIIC system, they could be featured in hypothetically ideal future research to determine their potential benefits. Second, the performance of a proposed WIIC system has been analyzed in order to reach 100 Gbps data rate. Third, a 60 GHz WIIC channel based on metamaterial Electronic Band Gap (EBG) absorbers has been designed and analyzed using the numerical electromagnetics solver HFSS® and this EBG is integrated into the representative WIIC channel. Moreover, the impulse response of the WIIC channel is numerically extracted and is used for the system validation and testing. Furthermore, the system has been simulated with the WIIC channel and the wired PCB channel. It has been found that, the Bit Error Rate (BER) performance of the proposed WIIC channel is close to that of an AWGN channel with FEC, and much better than the AWGN channel without FEC, which means that the designed WIIC system and channel work properly within the frequency band centered at 60 GHz, while the wired PCB channel is almost cut off at 15 GHz or higher for the cases investigated. With only five or six layers on a PCB board, the WIIC system is able to provide 384 Gbps data rate theoretically with 12 GHz bandwidth, while the wired PCB counterpart needs more than 20 layers in order to avoid severe SI problems and to properly layout the Tbps channels. The current version of the WIIC system is able to provide 24 Gbps data rate with the bandwidth of 12 GHz using OFDM and QPSK