End-to-End Simulation of 5G mmWave Networks

Due to its potential for multi-gigabit and low latency wireless links, millimeter wave (mmWave) technology is expected to play a central role in 5th generation cellular systems. While there has been considerable progress in understanding the mmWave physical layer, innovations will be required at all layers of the protocol stack, in both the access and the core network. Discrete-event network simulation is essential for end-to-end, cross-layer research and development. This paper provides a tutorial on a recently developed full-stack mmWave module integrated into the widely used open-source ns--3 simulator. The module includes a number of detailed statistical channel models as well as the ability to incorporate real measurements or ray-tracing data. The Physical (PHY) and Medium Access Control (MAC) layers are modular and highly customizable, making it easy to integrate algorithms or compare Orthogonal Frequency Division Multiplexing (OFDM) numerologies, for example. The module is interfaced with the core network of the ns--3 Long Term Evolution (LTE) module for full-stack simulations of end-to-end connectivity, and advanced architectural features, such as dual-connectivity, are also available. To facilitate the understanding of the module, and verify its correct functioning, we provide several examples that show the performance of the custom mmWave stack as well as custom congestion control algorithms designed specifically for efficient utilization of the mmWave channel.Comment: 25 pages, 16 figures, submitted to IEEE Communications Surveys and Tutorials (revised Jan. 2018

Indoor Geo-location And Tracking Of Mobile Autonomous Robot

The field of robotics has always been one of fascination right from the day of Terminator. Even though we still do not have robots that can actually replicate human action and intelligence, progress is being made in the right direction. Robotic applications range from defense to civilian, in public safety and fire fighting. With the increase in urban-warfare robot tracking inside buildings and in cities form a very important application. The numerous applications range from munitions tracking to replacing soldiers for reconnaissance information. Fire fighters use robots for survey of the affected area. Tracking robots has been limited to the local area under consideration. Decision making is inhibited due to limited local knowledge and approximations have to be made. An effective decision making would involve tracking the robot in earth co-ordinates such as latitude and longitude. GPS signal provides us sufficient and reliable data for such decision making. The main drawback of using GPS is that it is unavailable indoors and also there is signal attenuation outdoors. Indoor geolocation forms the basis of tracking robots inside buildings and other places where GPS signals are unavailable. Indoor geolocation has traditionally been the field of wireless networks using techniques such as low frequency RF signals and ultra-wideband antennas. In this thesis we propose a novel method for achieving geolocation and enable tracking. Geolocation and tracking are achieved by a combination of Gyroscope and encoders together referred to as the Inertial Navigation System (INS). Gyroscopes have been widely used in aerospace applications for stabilizing aircrafts. In our case we use gyroscope as means of determining the heading of the robot. Further, commands can be sent to the robot when it is off balance or off-track. Sensors are inherently error prone; hence the process of geolocation is complicated and limited by the imperfect mathematical modeling of input noise. We make use of Kalman Filter for processing erroneous sensor data, as it provides us a robust and stable algorithm. The error characteristics of the sensors are input to the Kalman Filter and filtered data is obtained. We have performed a large set of experiments, both indoors and outdoors to test the reliability of the system. In outdoors we have used the GPS signal to aid the INS measurements. When indoors we utilize the last known position and extrapolate to obtain the GPS co-ordinates

Characterization and Enhancement of Antenna System Performance in Compact MIMO Terminals

Co-band multiple-antenna implementation in compact user terminals is necessary for harvesting the full potential of diversity and multiple-input multiple-output (MIMO) technology in cellular communication systems. The recent worldwide deployment of Long Term Evolution (LTE), which requires the use of MIMO technology in the downlink, adds to the urgency of achieving both practical and optimal multiple-antenna systems in user terminals. Contrary to conventional understanding, an optimal multiple-antenna implementation does not only involve the design and placement of antenna elements in the terminals, but extends beyond the antenna elements and common antenna parameters to comprise interactions with the near field user and the propagation environment. Moreover, these interactions are non-static, which implies that the multiple-antenna system must adapt to the prevailing overall communication channel in order to assure the highest performance gains. This doctoral thesis aims to address several key issues in optimal multiple-antenna system design for compact multi-band MIMO terminals, with the first half (Papers I to III) focusing on the performance characterization of such terminals in the presence of user interaction and propagation channel, under the challenging constraint that the terminals are compact. The second half of the thesis (Papers IV to VI) considers two performance enhancement approaches suitable for compact MIMO terminals in realistic usage conditions. In particular, the potential benefits of harmonizing compact multiple-antenna systems with the propagation channel and user influence are determined with respect to reconfigurability in antenna patterns and impedance matching circuits. In Paper I, the diversity performance of internal multiple antennas with multi-band coverage in a mock-up with the size of a typical mobile handset is investigated in different user interaction scenarios. For comparison, a second mock-up with only one multi-band antenna is also evaluated in the same user cases. An ideal uniform propagation environment is assumed. The performance at frequency bands below and above 1 GHz are presented and analyzed in detail. Paper II extends the study in Paper I by evaluating the single-input multiple-output (SIMO) and MIMO capacity performance of the same antenna prototypes under the same user interaction scenarios and propagation environment. In Paper III, the impacts of gain imbalance and antenna separation on the throughput performance of a dual-dipole configuration are studied at frequencies below and above 1 GHz in a repeatable dynamic multi-path environment, using a live HSPA network. Since the compactness of a user terminal has implications on the antenna separation and gain imbalance of the multiple antennas, the focus is to gain knowledge on how these two factors affect the end user experience in practice. In Paper IV, three simple dual-antenna topologies implemented in compact smart phone prototypes of identical form factors are evaluated in MIMO channel measurements in noise-limited and interference-limited urban scenarios. Each dual-antenna topology is intentionally designed to provide a distinct set of antenna patterns. The goal is to investigate the potential of antenna system design as one of the key performance differentiators in real terminal implementations. Paper V extends the work in Paper IV by introducing user interaction to the same MIMO channel measurement setup. Furthermore, the focus of this paper is on the evaluation of both the average and local channel performances and their potential enhancements. Finally, Paper VI ascertains the potential capacity gains of applying uncoupled adaptive matching to a compact dual-antenna terminal in an indoor office environment, under a realistic user scenario. The performance gains are evaluated by means of extensive MIMO channel measurements at frequency bands below and above 1 GHz

User Effect Mitigation in MIMO Terminal Antennas

The rapid growth of cellular technology over the past decade transformed our lives, enabling billions of people to enjoy interactive multimedia content and ubiquitous connectivity through a device that can fit into the palm of a hand. In part the explosive growth of the smartphone market is enabled by innovative antenna system technologies, such as multiple-input multiple-output (MIMO) systems, facilitating high data rates and reliable connections. Even though future deployment of Long Term Evolution Advanced (LTE-A) is expected to provide seamless internet connectivity at even higher speeds over a wide range of devices with different form factors, fundamental terminal antenna limitations can severely impact the actual performance of the terminal. One of the key challenges in terminal antenna design are user-induced losses. It has been shown that electromagnetic absorption in body tissues as well as antenna impedance mismatch due to user proximity significantly degrade terminal antenna performance. Moreover, user interactions are non-static, which further complicates terminal design by leading to the requirement of evaluating a wide range of hand grips and usage scenarios. This doctoral thesis explores these challenges and offers useful insight on effective user interaction mitigation. In particular, state-of-the-art multiple antenna designs have been investigated in an attempt to formulate guidelines on efficient terminal antenna design in the presence of a user (Paper I). Moreover, the major part of the thesis considers the method of adaptive impedance matching (AIM) for performance enhancements of MIMO terminals. Both ideal and very practical and realistic AIM systems have been studied in order to extend the knowledge in the area by determining achievable performance gains and providing insights on AIM gain mechanisms for different terminal antenna designs, propagation environments and user scenarios. In Paper I, five different MIMO terminal antenna designs were evaluated in 11 representative user scenarios. Two of the prototypes were optimized with the Theory of Characteristic Modes (TCM), whereas the remaining three were based on more conventional antenna types. Multiplexing efficiency (ME) was used as the MIMO system performance metric, assuming an ideal uniform 3D propagation environment. The paper focuses on performance at frequency bands below 1 GHz due to the more stringent size limitations. Paper II presents a simulation model of the complete physical channel link based on ideal lossless AIM and evaluates the potential of AIM to mitigate user effects for three terminal antennas in four user scenarios. The prototypes studied have different performances in terms of bandwidth and isolation. MIMO capacity was used as the main performance metric. In order to gain insight on the impact of terminal bandwidth, as well as system bandwidth on AIM performance, capacity calculations were performed both for the center frequency and over the full LTE Band 13. In Paper III, a practical AIM system was set up and measured in both indoor and outdoor propagation scenarios for a one-hand and a two-hand grip, including a torso phantom. The AIM system consisted of two Maury mechanical tuners controlled with LabView. MIMO capacity was used to determine performance in the different user and channel cases. The impact of different propagation environments and user cases was discussed in detail. Moreover, tuner loss estimation was done to enable the calculation of AIM net gains. In Paper IV, the simulation model from Paper II was extended to include real antenna parameters as well as simulated environments with non-uniform angular power spectra. Two fundamentally different antenna designs were measured in three user scenarios involving phantom hands, whereas non-uniform environments of different angular spreads were simulated in post-processing. The study presents results and analysis on the impact of user scenarios and environment on the AIM gains for the terminals with different antenna designs. Finally, Paper V describes a realistic AIM system with custom-designed CMOS-SOI impedance tuners on a MIMO terminal antenna. Measurement setup control, as well as MIMO system evaluation, was achieved through a custom-developed LabView software. Detailed propagation measurements in three different environments with both phantom users and real test subjects were performed. The analysis and discussions provided insights on the practical implementation of AIM as well as on its performance in realistic conditions

Building Blocks of the Internet of Things: State of the Art and Beyond

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