Space time block codes (STBC) are a type of multiple input multiple output (MIMO) communications system that encode blocks of information into symbol sequences sent simultaneously from multiple antennas. MIMO communications systems have shown channel capacity improvement in multipath digital communications environments. The STBC class of MIMO communications systems can be easily decoded using linear combination and is resilient in the face of multipath channel effects. MIMO systems have traditionally been studied using theoretical analyses, simulations and real signal based experiments. Probabilistic models simulate channel effects as random variables, but are only estimates of actual conditions. Real signal experiments evaluate system performance under real-world conditions, but are not readily repeatable. Both modeling methods evaluate system performance in terms of the aggregate results. This dissertation research presents an approach that introduces controlled attenuation and delay to probabilistic channel models. This method allows the evaluation of MIMO system performance under specific channel conditions. The approach is demonstrated with a hardware accelerated STBC system model that is used to evaluate the performance of a MIMO system under controlled path conditions. The STBC system model utilizes a Xilinix® programmable gate array (PGA) device as a hardware accelerator. The model exploits the parallel processing capability of the PGA to simulate a nine path channel model and a three antenna rate ½ STBC. Novel implementations are developed for the additive white Gaussian noise (AWGN) sources and the linear MIMO decoding in PGA hardware. The model allows specification of overall noise and multipath fading effects for the channel as well as attenuation and phase delay for each channel path. Performance of the communications system is evaluated in terms of bit error rate (BER) versus signal-to-noise ratio (SNR). Hardware acceleration greatly reduces the time required to obtain simulation results. Reduced simulation time improves the use of the model by allowing evaluation of system performance under a greater number of conditions, greater performance curve resolution and evaluation at lower BER. The processing rate of the hardware accelerated model is compared to an equivalent software model. The model also provides an extensible platform for future research in communications theory. / Engineering

<p> The goal of this thesis is the development of a computationally-efficient coded system that enables communication over the non-coherent Multiple-Input Multiple-Output (MIMO) fiat-fading wireless channel at high data rates. The proposed signalling technique applies the principles of Bit-Interleaved Coded Modulation (BICM) with Iterative Demapping and Decoding (IDD) to non-coherent MIMO communication systems. </p> <p> The principle of BICM is applied to a constellation that mimics the non-coherent capacity achieving distribution at high signal to noise ratios. The capacity achieving distribution is in the form of isotropically distributed unitary matrices, and the constellation can be represented by points on a Grassmannian manifold. A mapping technique that exploits the Grassmannian geometry is proposed. This mapping technique is based on the partitioning of the constellation into two subsets. The Grassmannian geometry also gives rise to an efficient list-based demapping algorithm that substantially reduces the computational complexity of the receiver while incurring some degradation in performance. For example, at a bit error rate (BER) of 10-4 the signal to noise ratio (SNR) performance degradation with respect to full constellation demapping is approximately 1. 75 dB. A technique by which the decoder can augment the demapping list is proposed, and it is shown that the performance degradation of the efficient algorithm can be rendered insignificant (approximately 0.2 dB at a BER of 10-4). </p> <p> Finally, the performance of the proposed BICM-IDD using the Grassmannian constellation will be compared to that of a corresponding training-based BICM-IDD scheme. These simulations show that the proposed scheme can provide better performance at high data rates; e.g., for a data rate of 5/3 bits per channel use, the performance gap is almost 1 dB at BER of 10^(-4). </p> / Thesis / Master of Applied Science (MASc)

Yes / This study presents a wideband multiple-input-multiple-output (MIMO) antenna for Wifi/WLAN/LTE applications. The antenna consists of two triangular patches as the radiating elements placed orthogonally to each other. Two T-slots and a rectangular slot were etched on the ground plane to improve return loss and isolation. The total dimension of the proposed antenna is 30 x 30 mm2. The antenna yields impedance bandwidth of 101.7% between 2.28 GHz up to 7 GHz with a reflection coefficient of < -10 dB, and mutual coupling of < -14 dB. The results including S-Parameters, MIMO characteristics with analysis of envelope correlation coefficient (ECC), total active reflection coefficient (TARC), capacity loss, channel capacity, VSWR, antenna gain and radiation patterns are evaluated. These characteristics indicate that the proposed antenna is suitable for MIMO wireless applications.

no / This study presents an investigation of the mutual coupling between two printed elements antenna for a multiple-input-multiple-output (MIMO) antenna performance. It consists of two crescent shaped radiators placed symmetrically, and a neutralization line is applied to improve the mutual coupling. Theoretical and experimental characteristics are presented and compared. The antenna yields an achieved impedance bandwidth of 18.67 % (over 2.04–2.46 GHz) with a reflection coefficient <−10 dB and mutual coupling minimization of <−20 dB in addition to a reasonable and stable radiation pattern and envelope correlation.

Yes / In this work, miniaturized tunable two-antenna MIMO systems composed of printed F-slot shaped is developed to operate in the GPS, PCS, DCS and UMTS bands. The two-element MIMO antenna occupies a volume of 50 × 37.5 ×1.6 mm3, and is printed on an FR4 substrate. Initially, the frequency tunability of the MIMO antennas was verified by lumped capacitors with values between 0.75 to 2.75 pF to achieve a tuning range from 1.55 to 2.07GHz while the low mutual coupling between the radiators was accomplished by adding an I-shaped branch to a cut-away ground plane. The two antennas are then loaded with varactors to simultaneously achieve miniaturization and tunability. Simulation and measurement results demonstrate the successful implementation of a tunable MIMO with coupling reduction mechanism for a portable handheld wireless transceiver. The channel capacity of the proposed antenna is investigated and found to be close to that of an un-correlated system with efficient diversity in which the mutual coupling across the full bandwidth was better than -13dB. Owing to the compact size and ease of manufacture, the proposed antennas can be a promising solution for adaptive MIMO systems in handheld devices. / This work has been performed in the framework of ARTEMOS project under work programme ENIAC JU 2010 and FCT (Fundação para a Ciência e Tecnologia) .The authors would like to thank Datong PLC (Leeds LS18 4EG, West Yorkshire, U.K.), for their financial support of the Knowledge Transfer Partnership (KTP No: 008734).

Yes / A metasurface based decoupling structure that is composed of a square-wave slot pattern with exaggerated corners that is implemented on a rectangular microstrip provides high-isolation between adjacent patch antennas for Synthetic Aperture Radar (SAR) and Multi-Input-Multi-Output (MIMO) systems. The proposed 1×2 symmetric array antenna integrated with the proposed decoupling isolation structure is designed to operate at ISM bands of X, Ku, K, and Ka. With the proposed mutual coupling suppression technique (i) the average isolation in the respective ISM bands listed above is 7 dB, 10 dB, 5 dB, and 10 dB; and (ii) edge-to-edge gap between adjacent radiation elements is reduced to 10 mm (0.28λ). The average antenna gain improvement with the metasurface isolator is 2 dBi. / H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E0/22936/1

Yes / A dual-port transparent multiple-input multiple-output (MIMO) antenna resonating at sub-6 GHz 5G band is proposed by using patch/ground material as transparent conductive oxide (AgHT-8) and a transparent Plexiglas substrate. Two identical circular-shaped radiating elements fed by using a microstrip feedline are designed using the finite element method (FEM) based highfrequency structure simulator (HFSS) software. The effect of the isolation mechanism is discussed using two cases. In case 1, the two horizontally positioned elements are oriented in a similar direction with a separate ground plane, whereas in case 2, the elements are vertically placed facing opposite to each other with an allied ground. In both cases, the transparent antennas span over a −10 dB band of 4.65 to 4.97 GHz (300 MHz) with isolation greater than 15 dB among two elements. The diversity parameters are also analyzed for both the cases covering the correlation coefficient (ECC), mean effective gain (MEG), diversity gain (DG), and channel capacity loss (CCL). The average gain and efficiency above 1 dBi and 45%, respectively with satisfactory MIMO diversity performance, makes the transparent MIMO antenna an appropriate choice for smart IoT devices working in the sub-6 GHz 5G band by mitigating the co-site location and visual clutter issues. / This work is supported by the Moore4Medical project, funded within ECSEL JU in collaboration with the EU H2020 Framework Programme (H2020/2014-2020) under grant agreement H2020-ECSEL-2019-IA-876190, and Fundação para a Ciência e Tecnologia (ECSEL/0006/2019).

Yes / An offset quad-element, two-port, high-gain, and multiband multiple-input multiple-output (MIMO) planar antenna based on a log-periodic dipole array (LPDA) for Ku/K-band wireless communications is proposed, in this paper. A single element antenna has been designed starting from Carrel's theory and then optimized with a 50-Ω microstrip feed-line with two orthogonal branches that results mainly in a broadside radiation pattern and improves diversity parameters. For experimental confirmation, the designed structure is printed on an RT-5880 substrate with a thickness of 1.57 mm. The total substrate dimensions of the MIMO antenna are 55 × 45 mm2. According to the measured results, the designed structure is capable of working at 1.3% (12.82-12.98 GHz), 3.1% (13.54-13.96 GHz), 2.3% (14.81-15.15 GHz), 4.5% (17.7-18.52 GHz), and 4.6% (21.1-22.1 GHz) frequency bands. Additionally, the proposed MIMO antenna attains a peak gain of 4.2-10.7 dBi with maximum element isolation of 23.5 dB, without the use of any decoupling structure. Furthermore, the analysis of MIMO performance metrics such as the envelope correlation coefficient (ECC) and mean effective gain (MEG) validates good characteristics, and field correlation performance over the operating band. The proposed design is an appropriate option for multiband MIMO applications for various wireless systems in Ku/K-bands.

Present trends in communication links between devices have opted for wireless instead of wired solutions. As a consequence, unlicensed bands have seen a rise in the interference level as more and more devices are introduced into the market place that take advantage of these free bands for their communication needs. Under these conditions, the receiver's ability to recognize and identify the presence of interference becomes increasingly important. In order for the receiver to make an optimal decision on the signal-of-interest, it has to be aware of the type (modulation) of interference as well as how the received signals are affected (channel) by these impediments in order to appropriately mitigate them. This dissertation addresses the blind (unaided) identification of the signal modulations and the channel in a Multiple Input Multiple Output (MIMO) system. The method presented herein takes advantage of the modulation induced periodicities of the signals in the system and uses higher-order cyclostationary statistics to extract the signal and channel unknowns. This method can be used to identify more signals in the system than antenna elements at the receiver (overloaded case). This dissertation presents a system theoretic analysis of the problem as well as describes the development of an algorithm that can be used in the identification of the channel and the modulation of the signals in the system. Linear and non-linear receivers are examined at the beginning of the manuscript in order to review the a priori information that is needed for each receiver configuration to function properly. / Ph. D.

Smart antenna is a potential performance enhancement tool in a communications link that can be used at either end (transmitter or receiver) of the link in the form of beamforming or diversity operation. While receive smart antenna techniques and operations have matured over the years, transmit smart antenna is relatively a new concept that has seen its growth over the past few years. Both these smart antenna operations have been traditionally designed for base station applications. But with the advent of high-speed processors, transmit smart antenna can also be feasible at a small wireless terminal (SWT). This dissertation studied the feasibility of using smart antenna at a SWT. Both smart transmit and receive antennas are studied, including multiple input and multiple output (MIMO) systems, however the emphasis is placed on transmit smart antennas. The study includes algorithm developments and performance evaluations in both flat fading and frequency selective channels. Practical issues, i.e., latency and amount of feedback, related to transmit smart antenna operation are discussed. Various channel measurements are presented to assess the performance of a transmit smart antenna in a real propagation environment. These include vector channel measurements for narrowband and wideband signals, channel reciprocity, and effect of antenna element spacing on diversity performance. Real-time demonstrations of transmit smart antenna have been performed and presented, and, the applicability of the proposed techniques in the Third Generation standards and wireless local area networks (WLAN) is discussed. Receive beamforming with a small number of antenna elements (which is usually the case for a SWT) is analyzed in an interference-limited environment. / Ph. D.