Low Complexity Time-Concatenated Turbo Equalization for Block Transmission Without Guard Interval: Part 1—The Concept

This paper proposes a novel time-concatenated turbo equalization technique, chained turbo equalization (CHATUE), that allows block transmission systems to eliminate the guard interval (GI), while achieving excellent performance. The proposed CHATUE algorithm connects turbo equalizers neighboring in time, so that they exchange information about their inter-block-interference components in the form of a posteriori log-likelihood ratio. The latest version of the low complexity sub-optimal turbo equalization technique for block-wise single carrier transmission, frequency domain soft cancellation and minimum mean squared error, is fully exploited in developing the CHATUE algorithm. Results of extrinsic information transfer chart analysis as well as a series of bit-error rate (BER) simulations show that excellent performances can be achieved without imposing heavy computational burden in multipath-rich (quasi-static) block Rayleigh fading channels. It is shown that, if the information bit-rate is kept identical (because it may be unpreferable for the industry to change the frame structure), the CHATUE algorithm achieves lower BER than that with block transmission with GI, because lower rate (strong) code for error protection can be used by utilizing the time-duration made available by eliminating the GI. In addition, by combining the proposed structure with a simple rate-1 doped accumulator, further BER improvement exhibiting clear turbo cliff can be achieved. A sister paper (a Part-2 paper) applies the proposed CHATUE algorithm to single carrier frequency division multiple access systems Hui et al. (Wirel Pers Commun, 2011)

Simulación de una cadena de comunicaciones DS-CDMA - Simulació d’una cadena de comunicacions DS-CDMA

Català: En aquest projecte s'ha analitzat e implementat un sistema basat amb DSSS-CDMA amb un receptor comú y diversos transmissors sobre una plataforma modular en Matlab, essent aquesta una eina de validació teòrica. S'ha primat aquesta per sobre d'una implementació en DSP principalment pel cost ecònomic de les plaques DSP. Així, s'ha decidit fer una implementació en Matlab amb les restriccions pròpies d'una placa DSP. El principal objectiu del projecte es la validació del sistema mitjançant la simulació a nivell de mostra sense restriccions de memòria. El proper pas seria la implementació en plaques DSP, peró això s'escapa del objectiu d'aquest projecte. És per això que s'ha dissenyat un sistema que pugi processar les dades amb pocs recursos mitjançant Matlab, tots marcats per una serie de variables. El transmissor es composa de diversos mòduls invariants que son el codificador, modulador, spreader, zero padder, pols conformador i el up converter que estan encadenats per generar la senyal a transmetre per cada un dels diversos usuaris. Totes aquestes senyals passen per un canal d'esvaniment lent amb soroll Gaussià blanc que modelitza un medi de comunicacions mòbil. Finalment el receptor rep totes les senyals y les processa en una serie de mòduls independents formats per un filtre pas baix, downconverter, filtre adaptat, sincronitzador, downsampler, equalitzador, despreader, demodulador y decodificador. En aquest treball es pot observar en la secció de Resultats les captures de la senyal a cada una de les diverses fases seguides d'una breu explicació. Finalment es tracten les conclusions i les properes vies d'investigació.Castellano: En este proyecto se ha analizado e implementado un sistema basado en DSSS-CDMA con un receptor común y varios transmisores sobre una plataforma modular en Matlab, siendo ésta una herramienta de validación teórica. Se ha primado esta sobre una implementación en DSP por el coste económico de las placas DSP. Así que se ha decidido hacer una implementación en Matlab con las constricciones propias de una placa DSP. El objetivo principal del proyecto es la validación del sistema mediante la simulación a nivel de muestra sin restricciones de memoria. El siguiente paso sería la implementación en placas DSP pero esto se escapa del objetivo de este proyecto. Para ello se ha diseñado un sistema que pueda procesar los datos con pocos recursos en Matlab, marcados por una serie de variables. El transmisor se compone de varios módulos invariantes que son el codificador, modulador, spreader, zero padder, pulse shaper y el up converter que encadenados generan la señal a transmitir de cada uno de los distintos usuarios. Todas estas señales pasan por un canal con desvanecimientos lentos y ruido aditivo gaussiano que modeliza un medio de comunicaciones móvil. Finalmente el receptor recibe todas las señales y las procesa en una serie de módulos independientes formados por un filtro paso bajo, downconverter, filtro adaptado, sincronizador, downsampler, equalizador, despreader, demodulador y decodificador. En este trabajo se puede observar en la sección Resultados las capturas de la señal en cada una de las distintas fases seguida de una breve explicación. Para finalmente llegar a la sección de Conclusiones y Futuras líneas de investigación.English: This project has analyzed and implemented a system based on DS-CDMA with a common receiver and multiple transmitters on a modular platform in Matlab, which is used for theoretical validation tool. This platform has been chosen over a DSP implementation due to the economic cost of DSP boards. So, it was decided to implement it using Matlab considering the inherent constraints in a DSP board. Project's main objective is to validate this system by having a simulation at a sample level which has no memory constraints. The next step would be to implement this in DSP boards; however this is beyond the scope of this project. A system has been designed that can process data with few resources in Matlab environment. The system developed is highly configurable using some input parameters. The transmitter consists of several modules that are invariant which are encoder, modulator, spreader, zero padder, pulse shaper and converter. These chained modules generate each user transmitted signal. Once these transmittersâ signals have been generated, they pass through a slowly fading channel with additive Gaussian noise which models a means of mobile communications. Ultimately the receiver gets all signals and processes them in a series of independent modules consisting of a low pass filter, downconverter, matched filter, synchronizer, downsampler, equalizer, despreader, demodulator and decoder. This work can be seen in the â Resultsâ section where there are screens of the signal in each of the phases followed by a brief justification

Doppler compensation algorithms for DSP-based implementation of OFDM underwater acoustic communication systems

In recent years, orthogonal frequency division multiplexing (OFDM) has gained considerable attention in the development of underwater communication (UWC) systems for civilian and military applications. However, the wideband nature of the communication links necessitate robust algorithms to combat the consequences of severe channel conditions such as frequency selectivity, ambient noise, severe multipath and Doppler Effect due to velocity change between the transmitter and receiver. This velocity perturbation comprises two scenarios; the first induces constant time scale expansion/compression or zero acceleration during the transmitted packet time, and the second is time varying Doppler-shift. The latter is an increasingly important area in autonomous underwater vehicle (AUV) applications. The aim of this thesis is to design a low complexity OFDM-based receiver structure for underwater communication that tackles the inherent Doppler effect and is applicable for developing real-time systems on a digital signal processor (DSP). The proposed structure presents a paradigm in modem design from previous generations of single carrier receivers employing computationally expensive equalizers. The thesis demonstrates the issues related to designing a practical OFDM system, such as channel coding and peak-to-average power ratio (PAPR). In channel coding, the proposed algorithms employ convolutional bit-interleaved coded modulation with iterative decoding (BICM-ID) to obtain a higher degree of protection against power fading caused by the channel. A novel receiver structure that combines an adaptive Doppler-shift correction and BICM-ID for multi-carrier systems is presented. In addition, the selective mapping (SLM) technique has been utilized for PAPR. Due to their time varying and frequency selective channel nature, the proposed systems are investigated via both laboratory simulations and experiments conducted in the North Sea off the UK’s North East coast. The results of the study show that the proposed systems outperform block-based Doppler-shift compensation and are capable of tracking the Doppler-shift at acceleration up to 1m /s2.EThOS - Electronic Theses Online ServiceIraqi Government's Ministry of Higher Education and Scientific ResearchGBUnited Kingdo

Simulación de una cadena de comunicaciones DS-CDMA - Simulació d’una cadena de comunicacions DS-CDMA

Català: En aquest projecte s'ha analitzat e implementat un sistema basat amb DSSS-CDMA amb un receptor comú y diversos transmissors sobre una plataforma modular en Matlab, essent aquesta una eina de validació teòrica. S'ha primat aquesta per sobre d'una implementació en DSP principalment pel cost ecònomic de les plaques DSP. Així, s'ha decidit fer una implementació en Matlab amb les restriccions pròpies d'una placa DSP. El principal objectiu del projecte es la validació del sistema mitjançant la simulació a nivell de mostra sense restriccions de memòria. El proper pas seria la implementació en plaques DSP, peró això s'escapa del objectiu d'aquest projecte. És per això que s'ha dissenyat un sistema que pugi processar les dades amb pocs recursos mitjançant Matlab, tots marcats per una serie de variables. El transmissor es composa de diversos mòduls invariants que son el codificador, modulador, spreader, zero padder, pols conformador i el up converter que estan encadenats per generar la senyal a transmetre per cada un dels diversos usuaris. Totes aquestes senyals passen per un canal d'esvaniment lent amb soroll Gaussià blanc que modelitza un medi de comunicacions mòbil. Finalment el receptor rep totes les senyals y les processa en una serie de mòduls independents formats per un filtre pas baix, downconverter, filtre adaptat, sincronitzador, downsampler, equalitzador, despreader, demodulador y decodificador. En aquest treball es pot observar en la secció de Resultats les captures de la senyal a cada una de les diverses fases seguides d'una breu explicació. Finalment es tracten les conclusions i les properes vies d'investigació.Castellano: En este proyecto se ha analizado e implementado un sistema basado en DSSS-CDMA con un receptor común y varios transmisores sobre una plataforma modular en Matlab, siendo ésta una herramienta de validación teórica. Se ha primado esta sobre una implementación en DSP por el coste económico de las placas DSP. Así que se ha decidido hacer una implementación en Matlab con las constricciones propias de una placa DSP. El objetivo principal del proyecto es la validación del sistema mediante la simulación a nivel de muestra sin restricciones de memoria. El siguiente paso sería la implementación en placas DSP pero esto se escapa del objetivo de este proyecto. Para ello se ha diseñado un sistema que pueda procesar los datos con pocos recursos en Matlab, marcados por una serie de variables. El transmisor se compone de varios módulos invariantes que son el codificador, modulador, spreader, zero padder, pulse shaper y el up converter que encadenados generan la señal a transmitir de cada uno de los distintos usuarios. Todas estas señales pasan por un canal con desvanecimientos lentos y ruido aditivo gaussiano que modeliza un medio de comunicaciones móvil. Finalmente el receptor recibe todas las señales y las procesa en una serie de módulos independientes formados por un filtro paso bajo, downconverter, filtro adaptado, sincronizador, downsampler, equalizador, despreader, demodulador y decodificador. En este trabajo se puede observar en la sección Resultados las capturas de la señal en cada una de las distintas fases seguida de una breve explicación. Para finalmente llegar a la sección de Conclusiones y Futuras líneas de investigación.English: This project has analyzed and implemented a system based on DS-CDMA with a common receiver and multiple transmitters on a modular platform in Matlab, which is used for theoretical validation tool. This platform has been chosen over a DSP implementation due to the economic cost of DSP boards. So, it was decided to implement it using Matlab considering the inherent constraints in a DSP board. Project's main objective is to validate this system by having a simulation at a sample level which has no memory constraints. The next step would be to implement this in DSP boards; however this is beyond the scope of this project. A system has been designed that can process data with few resources in Matlab environment. The system developed is highly configurable using some input parameters. The transmitter consists of several modules that are invariant which are encoder, modulator, spreader, zero padder, pulse shaper and converter. These chained modules generate each user transmitted signal. Once these transmittersâ signals have been generated, they pass through a slowly fading channel with additive Gaussian noise which models a means of mobile communications. Ultimately the receiver gets all signals and processes them in a series of independent modules consisting of a low pass filter, downconverter, matched filter, synchronizer, downsampler, equalizer, despreader, demodulator and decoder. This work can be seen in the â Resultsâ section where there are screens of the signal in each of the phases followed by a brief justification

Assessment and Real Time Implementation of Wireless Communications Systems and Applications in Transportation Systems

Programa Oficial de Doutoramento en Tecnoloxías da Información e das Comunicacións en Redes Móbiles. 5029V01[Resumo] Os sistemas de comunicación sen fíos de cuarta e quinta xeración (4G e 5G) utilizan unha capa física (PHY) baseada en modulacións multiportadora para a transmisión de datos cun gran ancho de banda. Este tipo de modulacións proporcionan unha alta eficiencia espectral á vez que permiten corrixir de forma sinxela os efectos da canle radio. Estes sistemas utilizan OFDMA como mecanismo para a repartición dos recursos radio dispoñibles entre os diferentes usuarios. Este repartimento realízase asignando un subconxunto de subportadoras a cada usuario nun instante de tempo determinado. Isto aporta unha gran flexibilidade ó sistema que lle permite adaptarse tanto ós requisitos de calidade de servizo dos usuarios como ó estado da canle radio. A capa de acceso ó medio (MAC) destes sistemas encárgase de configurar os diversos parámetros proporcionados pola capa física OFDMA, ademais de xestionar os diversos fluxos de información de cada usuario, transformando os paquetes de capas superiores en paquetes da capa física. Neste traballo estúdase o deseño e implementación das capas MAC e PHY de sistemas de comunicación 4G ademais da súa aplicabilidade en sistemas de transporte ferroviarios. Por unha parte, abórdase o deseño e implementación en tempo real do estándar WiMAX. Estúdanse os mecanismos necesarios para establecer comunicacións bidireccionais entre unha estación base e múltiples dispositivos móbiles. Ademais, estúdase como realizar esta implementación nunha arquitectura hardware baseada en DSPs e FPGAs, na que se implementan as capas MAC e PHY. Dado que esta arquitectura ten uns recursos computacionais limitados, tamén se estudan as necesidades de cada módulo do sistema para poder garantir o funcionamento en tempo real do sistema completo. Por outra parte, tamén se estuda a aplicabilidade dos sistemas 4G a sistemas de transporte públicos. Os sistemas de comunicacións e sinalización son unha parte vital para os sistemas de transporte ferroviario e metro. As comunicacións sen fíos utilizadas por estes sistemas deben ser robustas e proporcionar unha alta fiabilidade para permitir a supervisión, control e seguridade do tráfico ferroviario. Para levar a cabo esta avaliación de viabilidade realízanse simulacións de redes de comunicacións LTE en contornos de transporte ferroviarios, comprobando o cumprimento dos requisitos de fiabilidade e seguridade. Realízanse diferentes simulacións do sistema de comunicacións para poder ser avaliadas e seleccionar a configuración e arquitectura do sistema máis axeitada en función do escenario considerado. Tamén se efectúan simulacións de redes baseadas en Wi-Fi, dado que é a solución máis utilizada nos metros, para confrontar os resultados cos obtidos para LTE. Para que os resultados das simulacións sexan realistas débense empregar modelos de propagación radio axeitados. Nas simulacións utilízanse tanto modelos deterministas como modelos baseados nos resultados de campañas de medida realizadas nestes escenarios. Nas simulacións empréganse os diferentes fluxos de información destes escenarios para comprobar que se cumpren os requisitos de calidade de servicio (QoS). Por exemplo, os fluxos críticos para o control ferroviario, como European Train Control System (ETCS) ou Communication-Based Train Control (CBTC), necesitan unha alta fiabilidade e un retardo mínimo nas comunicacións para garantir o correcto funcionamento do sistema.[Resumen] Los sistemas de comunicación inalámbricos de cuarta y quinta generación (4G y 5G) utilizan una capa física (PHY) basada en modulaciones multiportadora para la transmisión de datos con un gran ancho de banda. Este tipo de modulaciones han demostrado tener una alta eficiencia espectral a la vez que permiten corregir de forma sencilla los efectos del canal radio. Estos sistemas utilizan OFDMA como mecanismo para el reparto de los recursos radio disponibles entre los diferentes usuarios. Este reparto se realiza asignando un subconjunto de subportadoras a cada usuario en un instante de tiempo determinado. Esto aporta una gran flexibilidad al sistema que le permite adaptarse tanto a los requisitos de calidad de servicio de los usuarios como al estado del canal radio. La capa de acceso al medio (MAC) de estos sistemas se encarga de configurar los diversos parámetros proporcionados por la capa física OFDMA, además de gestionar los diversos flujos de información de cada usuario, transformando los paquetes de capas superiores en paquetes de la capa física. En este trabajo se estudia el diseño e implementación de las capas MAC y PHY de sistemas de comunicación 4G además de su aplicabilidad en sistemas de transporte ferroviarios. Por una parte, se aborda el diseño e implementación en tiempo real del estándar WiMAX. Se estudian los mecanismos necesarios para establecer comunicaciones bidireccionales entre una estación base y múltiples dispositivos móviles. Además, se estudia cómo realizar esta implementación en una arquitectura hardware basada en DSPs y FPGAs, en la que se implementan las capas MAC y PHY. Dado que esta arquitectura tiene unos recursos computacionales limitados, también se estudian las necesidades de cada módulo del sistema para poder garantizar el funcionamiento en tiempo real del sistema completo. Por otra parte, también se estudia la aplicabilidad de los sistemas 4G a sistemas de transporte públicos. Los sistemas de comunicaciones y señalización son una parte vital para los sistemas de transporte ferroviario y metro. Las comunicaciones inalámbricas utilizadas por estos sistemas deben ser robustas y proporcionar una alta fiabilidad para permitir la supervisión, control y seguridad del tráfico ferroviario. Para llevar a cabo esta evaluación de viabilidad se realizan simulaciones de redes de comunicaciones LTE en entornos de transporte ferroviarios, comprobando si se cumplen los requisitos de fiabilidad y seguridad. Se realizan diferentes simulaciones del sistema de comunicaciones para poder ser evaluados y seleccionar la configuración y arquitectura del sistema más adecuada en función del escenario planteado. También se efectúan simulaciones de redes basadas en Wi-Fi, dado que es la solución más utilizada en los metros, para comparar los resultados con los obtenidos para LTE. Para que los resultados de las simulaciones sean realistas se deben utilizar modelos de propagación radio apropiados. En las simulaciones se utilizan tanto modelos deterministas como modelos basados en los resultados de campañas de medida realizadas en estos escenarios. En las simulaciones se utilizan los diferentes flujos de información de estos escenarios para comprobar que se cumplen sus requisitos de calidad de servicio. Por ejemplo, los flujos críticos para el control ferroviario, como European Train Control System (ETCS) o Communication-Based Train Control (CBTC), necesitan una alta fiabilidad y un retardo bajo en las comunicaciones para garantizar el correcto funcionamiento del sistema.[Abstract] The fourth and fifth generation wireless communication systems (4G and 5G) use a physical layer (PHY) based on multicarrier modulations for data transmission using high bandwidth. This type of modulations has shown to provide high spectral efficiency while allowing low complexity radio channel equalization. These systems use OFDMA as a mechanism for distributing the available radio resources among different users. This allocation is done by assigning a subset of subcarriers to each user in a given instant of time. This provides great flexibility to the system that allows it to adapt to both the quality of service requirements of users and the radio channel state. The media access layer (MAC) of these systems is in charge of configuring the multiple OFDMA PHY layer parameters, in addition to managing the data flows of each user, transforming the higher layer packets into PHY layer packets. This work studies the design and implementation of MAC and PHY layers of 4G communication systems as well as their applicability in rail transport systems. On the one hand, the design and implementation in real time of the WiMAX standard is addressed. The required mechanisms to establish bidirectional communications between a base station and several mobile devices are also evaluated. Moreover, a MAC layer and PHY layer implementation is presented, using a hardware architecture based in DSPs and FPGAs. Since this architecture has limited computational resources, the requirements of each processing block of the system are also studied in order to guarantee the real time operation of the complete system. On the other hand, the applicability of 4G systems to public transportation systems is also studied. Communications and signaling systems are a vital part of rail and metro transport systems. The wireless communications used by these systems must be robust and provide high reliability to enable the supervision, control and safety of rail traffic. To carry out this feasibility assessment, LTE communications network simulations are performed in rail transport environments to verify that reliability and safety requirements are met. Several simulations are carried out in order to evaluate the system performance and select the most appropriate system configuration in each case. Simulations of Wi-Fi based networks are also carried out, since it is the most used solution in subways, to compare the results with those obtained for LTE. To perform the simulations correctly, appropriate radio propagation models must be used. Both deterministic models and models based on the results of measurement campaigns in these scenarios are used in the simulations. The simulations use the different information flows present in the railway transportation systems to verify that its quality of service requirements are met. For example, critical flows for railway control, such as the European Train Control System (ETCS) or Communication-Based Train Control (CBTC), require high reliability and low delay communications to ensure the proper functioning of the system

Baseband Processing for 5G and Beyond: Algorithms, VLSI Architectures, and Co-design

In recent years the number of connected devices and the demand for high data-rates have been significantly increased. This enormous growth is more pronounced by the introduction of the Internet of things (IoT) in which several devices are interconnected to exchange data for various applications like smart homes and smart cities. Moreover, new applications such as eHealth, autonomous vehicles, and connected ambulances set new demands on the reliability, latency, and data-rate of wireless communication systems, pushing forward technology developments. Massive multiple-input multiple-output (MIMO) is a technology, which is employed in the 5G standard, offering the benefits to fulfill these requirements. In massive MIMO systems, base station (BS) is equipped with a very large number of antennas, serving several users equipments (UEs) simultaneously in the same time and frequency resource. The high spatial multiplexing in massive MIMO systems, improves the data rate, energy and spectral efficiencies as well as the link reliability of wireless communication systems. The link reliability can be further improved by employing channel coding technique. Spatially coupled serially concatenated codes (SC-SCCs) are promising channel coding schemes, which can meet the high-reliability demands of wireless communication systems beyond 5G (B5G). Given the close-to-capacity error correction performance and the potential to implement a high-throughput decoder, this class of code can be a good candidate for wireless systems B5G. In order to achieve the above-mentioned advantages, sophisticated algorithms are required, which impose challenges on the baseband signal processing. In case of massive MIMO systems, the processing is much more computationally intensive and the size of required memory to store channel data is increased significantly compared to conventional MIMO systems, which are due to the large size of the channel state information (CSI) matrix. In addition to the high computational complexity, meeting latency requirements is also crucial. Similarly, the decoding-performance gain of SC-SCCs also do come at the expense of increased implementation complexity. Moreover, selecting the proper choice of design parameters, decoding algorithm, and architecture will be challenging, since spatial coupling provides new degrees of freedom in code design, and therefore the design space becomes huge. The focus of this thesis is to perform co-optimization in different design levels to address the aforementioned challenges/requirements. To this end, we employ system-level characteristics to develop efficient algorithms and architectures for the following functional blocks of digital baseband processing. First, we present a fast Fourier transform (FFT), an inverse FFT (IFFT), and corresponding reordering scheme, which can significantly reduce the latency of orthogonal frequency-division multiplexing (OFDM) demodulation and modulation as well as the size of reordering memory. The corresponding VLSI architectures along with the application specific integrated circuit (ASIC) implementation results in a 28 nm CMOS technology are introduced. In case of a 2048-point FFT/IFFT, the proposed design leads to 42% reduction in the latency and size of reordering memory. Second, we propose a low-complexity massive MIMO detection scheme. The key idea is to exploit channel sparsity to reduce the size of CSI matrix and eventually perform linear detection followed by a non-linear post-processing in angular domain using the compressed CSI matrix. The VLSI architecture for a massive MIMO with 128 BS antennas and 16 UEs along with the synthesis results in a 28 nm technology are presented. As a result, the proposed scheme reduces the complexity and required memory by 35%–73% compared to traditional detectors while it has better detection performance. Finally, we perform a comprehensive design space exploration for the SC-SCCs to investigate the effect of different design parameters on decoding performance, latency, complexity, and hardware cost. Then, we develop different decoding algorithms for the SC-SCCs and discuss the associated decoding performance and complexity. Also, several high-level VLSI architectures along with the corresponding synthesis results in a 12 nm process are presented, and various design tradeoffs are provided for these decoding schemes

Towards Scalable Design of Future Wireless Networks

Wireless operators face an ever-growing challenge to meet the throughput and processing requirements of billions of devices that are getting connected. In current wireless networks, such as LTE and WiFi, these requirements are addressed by provisioning more resources: spectrum, transmitters, and baseband processors. However, this simple add-on approach to scale system performance is expensive and often results in resource underutilization. What are, then, the ways to efficiently scale the throughput and operational efficiency of these wireless networks? To answer this question, this thesis explores several potential designs: utilizing unlicensed spectrum to augment the bandwidth of a licensed network; coordinating transmitters to increase system throughput; and finally, centralizing wireless processing to reduce computing costs. First, we propose a solution that allows LTE, a licensed wireless standard, to co-exist with WiFi in the unlicensed spectrum. The proposed solution bridges the incompatibility between the fixed access of LTE, and the random access of WiFi, through channel reservation. It achieves a fair LTE-WiFi co-existence despite the transmission gaps and unequal frame durations. Second, we consider a system where different MIMO transmitters coordinate to transmit data of multiple users. We present an adaptive design of the channel feedback protocol that mitigates interference resulting from the imperfect channel information. Finally, we consider a Cloud-RAN architecture where a datacenter or a cloud resource processes wireless frames. We introduce a tree-based design for real-time transport of baseband samples and provide its end-to-end schedulability and capacity analysis. We also present a processing framework that combines real-time scheduling with fine-grained parallelism. The framework reduces processing times by migrating parallelizable tasks to idle compute resources, and thus, decreases the processing deadline-misses at no additional cost. We implement and evaluate the above solutions using software-radio platforms and off-the-shelf radios, and confirm their applicability in real-world settings.PhDElectrical Engineering: SystemsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133358/1/gkchai_1.pd

Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

Cellular, Wide-Area, and Non-Terrestrial IoT: A Survey on 5G Advances and the Road Towards 6G

The next wave of wireless technologies is proliferating in connecting things among themselves as well as to humans. In the era of the Internet of things (IoT), billions of sensors, machines, vehicles, drones, and robots will be connected, making the world around us smarter. The IoT will encompass devices that must wirelessly communicate a diverse set of data gathered from the environment for myriad new applications. The ultimate goal is to extract insights from this data and develop solutions that improve quality of life and generate new revenue. Providing large-scale, long-lasting, reliable, and near real-time connectivity is the major challenge in enabling a smart connected world. This paper provides a comprehensive survey on existing and emerging communication solutions for serving IoT applications in the context of cellular, wide-area, as well as non-terrestrial networks. Specifically, wireless technology enhancements for providing IoT access in fifth-generation (5G) and beyond cellular networks, and communication networks over the unlicensed spectrum are presented. Aligned with the main key performance indicators of 5G and beyond 5G networks, we investigate solutions and standards that enable energy efficiency, reliability, low latency, and scalability (connection density) of current and future IoT networks. The solutions include grant-free access and channel coding for short-packet communications, non-orthogonal multiple access, and on-device intelligence. Further, a vision of new paradigm shifts in communication networks in the 2030s is provided, and the integration of the associated new technologies like artificial intelligence, non-terrestrial networks, and new spectra is elaborated. Finally, future research directions toward beyond 5G IoT networks are pointed out.Comment: Submitted for review to IEEE CS&