Area spectral efficiency of soft-decision space–time–frequency shift-keying-aided slow-frequency-hopping multiple access

Slow-frequency-hopping multiple access (SFHMA) can provide inherent frequency diversity and beneficially randomize the effects of cochannel interference. It may also be advantageously combined with our novel space-time–frequency shift keying (STFSK) scheme. The proposed system’s area spectral efficiency is investigated in various cellular frequency reuse structures. Furthermore, it is compared to both classic Gaussian minimum shift keying (GMSK)-aided SFHMA and GMSK-assisted time- division/frequency-division multiple access (TD/FDMA). The more sophisticated third-generation wideband code-division multiple access (WCDMA) and the fourth-generation Long Term Evolution (LTE) systems were also included in our comparisons. We demonstrate that the area spectral efficiency of the STFSK-aided SFHMA system is higher than the GMSK-aided SFHMA and TD/FDMA systems, as well as WCDMA, but it is only 60% of the LTE system

A Tutorial on the Tracking, Telemetry, and Command (TT&C) for Space Missions

This paper presents a tutorial on the Tracking, Telemetry, and Command (TT&C) for spacecraft and satellite missions. In particular, it provides a thorough summary of the design of the TT&C, starting from elementary system aspects and going down to the details of the on-board TT&C subsystem design, its units, and the physical layer. The paper is then complemented with a description of emerging TT&C techniques and technologies, the standardization framework, and practical examples of actual spacecraft design of European space missions. The here-presented tutorial is thought for professionals (also in other telecommunication engineering fields) willing to face the challenges and state-of-the-art of the TT&C, and know more about this fundamental function that allows us to control and monitor our spacecraft on a daily basis

Study of continuous-phase four-state modulation for cordless telecommunications. Assessment by simulation of CP-QFSK as an alternative modulation scheme for TDMA digital cordless telecommunications systems operating in indoor applications

One of the major driving elements behind the explosive boom in wireless revolution is the advances in the field of modulation which plays a fundamental role in any communication system, and especially in cellular radio systems. Hence, the elaborate choice of an efficient modulation scheme is of paramount importance in the design and employment of any communications system. Work presented in this thesis is an investigation (study) of the feasibility of whether multilevel FSK modulation scheme would provide a viable alternative modem that can be employed in TDMA cordless communications systems. In the thesis the design and performance analysis of a non-coherent multi-level modem that offers a great deal of bandwidth efficiency and hardware simplicity is studied in detail. Simulation results demonstrate that 2RC pre-modulation filter pulse shaping with a modulation index of 0.3, and pre-detection filter normalized equivalent noise bandwidth of 1.5 are optimum system parameter values. Results reported in chapter 5 signify that an adjacent channel rejection factor of around 40 dB has been achieved at channel spacing of 1.5 times the symbol rate while the DECT system standards stipulated a much lower rejection limit criterion (25-30dB), implying that CP-QFSK modulation out-performs the conventional GMSK as it causes significantly less ACI, thus it is more spectrally efficient in a multi-channel system. However, measured system performance in terms of BER indicates that this system does not coexist well with other interferers as at delay spreads between 100ns to 200ns, which are commonly encountered in such indoor environment, a severe degradation in system performance apparently caused by multi-path fading has been noticed, and there exists a noise floor of about 40 dB, i.e. high irreducible error rate of less than 5.10-3. Implementing MRC diversity combiner and BCH codec has brought in a good gain.Higher Education Ministr

Hybrid optical fiber-wireless communication to support tactile internet

5G technologies are systems that will set to change the way people, devices and machines connect. This generation of mobile services provide connection in just one click. The advanced 5G infrastructure, defined as “ubiquitous ultra-broadband network supporting future Internet”, represents a revolution in the telecommunications field. It will enable new secure and reliable services to everyone and everything with ultra-low latency. “Full Immersive Experience”, enriched by “Context Information” and “Anything as a Service” are the main drivers for a substantial adoption of the fifth generation networks [1]. The technical challenges that must be taken into account in the design of the 5G system are many and unprecedented. Therefore,5G is expected to be about 10 times faster than LTE-4G, in addition, it is projected that this network will have100-1000 times higher system capacity, user data rates in the order of Gbps everywhere, 10-100 higher number of connected devices per area, latency in the order of 1 millisecond, and 10 times longer battery life for devices. Due to all these technological changes, for years, researchers, suppliers and manufacturers around the world have studied this new network. In order to transform the user's wireless experience and be able to offer fast generalized connectivity anytime, anywhere, to any device.[2]. All this requires an enabler in the new approach of radio access networks, which could be hybrid optical Fiber-Wireless communications. “Photonics technology has been recognized by the European Union as a Key Enabling Technology (KET), which is a technology that enables a market, many times larger than the market of technology itself”. Photonic techniques have become key enablers to unlock future broadband wireless communications with terabit data rates in order to support the current trends of mobile data traffic[3]. The aim of this thesis is to conceive experimentally and validate 1 millisecond latency hybrid optical Fiber-Wireless access links support for tactile Internet taking into account the system requirements. For this purpose, first a review about the implementation of high-speed data links at 75-110 GHz band with low latency was made. Likewise, this work summarizes the components of hybrid optical Fiber-Wireless communication in W- Band. Second, measurements of the delay contribution from individual elements in the W -Band hybrid system were made. In addition, the main contribution was to develop a procedure for measuring latency physically using software defined radio (SDR) and estimating the overall system latency. In this procedure, potential sources of delay can be identified in current high-data-rate hybrid optical-RF communication systems. After knowing how to measure latency in a hybrid optical Fiber-Wireless system, the following objectives were developed: to test an appropriate multiplexing scheme such as Orthogonal Frequency Division Multiplexing (OFDM), and Generalized Frequency Division Multiplexing (GFDM), to achieve the lowest latency with improved performance; and to implement WDM (Wavelength Division Multiplexing) to achieve the required low latency.Resumen: Las tecnologías 5G son sistemas de generación de servicios móviles configurados para cambiar la forma en que las personas, los dispositivos y las máquinas se conectan. La infraestructura 5G está definida como una red ubicua de banda ultra-ancha que soportará Internet en el futuro, dicha red representa una revolución en el campo de las telecomunicaciones. Permitirá eficientemente nuevos servicios ultra-confiables, rápidos y seguros, preservando la privacidad y acelerando los servicios críticos para todos y para cada cosa. Estas redes son la evolución del Internet de las cosas, en donde cada una de ellas es tratada como un objeto cognitivo formando sistemas cibernéticos (CPS). La "experiencia de inmersión total", enriquecida con "información de contexto" y "todo como un servicio" son los principales impulsores para una adopción masiva de los nuevos componentes de ésta tecnología y su aceptación del mercado [1]. Se espera que 5G sea aproximadamente 10 veces más rápido que 4G LTE. Por lo tanto, los desafíos técnicos que deben abordarse en el diseño del sistema 5G son muchos y sin precedentes. Actualmente hay varias actividades en todo el mundo para capturar las aplicaciones y los requisitos para 5G, algunas empresas proveedoras de servicio y fabricantes incluso ya han realizado pruebas para la implementación de dichas redes. Algunos de los principales requisitos que demandan estas redes se pueden resumir en: 100-1000 veces más capacidad del sistema, tasas de datos de usuario en el orden de Gbps en todas partes, latencia en el orden de 1 milisegundo, 10-100 veces mayor número de dispositivos conectados por área, 10 veces más duración de la batería para dispositivos. Estos requisitos transformarán dramáticamente la experiencia inalámbrica de un usuario en un sistema 5G al ofrecer conectividad generalizada rápida en cualquier momento, en cualquier lugar, a cualquier dispositivo [2]. Todo esto requiere un habilitador en el nuevo enfoque de las redes de acceso por radio, que podrían ser comunicaciones híbridas de fibra óptica y transmisiones inalámbricas vía radio. La fotónica por su parte ha sido reconocida por la Unión Europea como una Tecnología Clave Habilitadora (KET), una tecnología que permite un mercado que es muchas veces más grande que el mercado de la tecnología en sí. Las técnicas fotónicas combinadas con la generación de microondas en lo que se conoce en su término en inglés como microwave-photonics se han convertido en habilitadores clave para desbloquear futuras comunicaciones inalámbricas de banda ancha con tasas de datos de terabit a fin de soportar las tendencias actuales del tráfico de datos móviles [3]. El objetivo de esta tesis es concebir experimentalmente y validar enlaces de acceso híbridos de fibra óptica-radio, cuya latencia sea de 1 milisegundo con el fin de soportar Internet táctil, el cual es una aplicación de 5G, teniendo en cuenta los requisitos del sistema. Para ello, primero se realizó una investigación sobre la implementación de enlaces de datos con redes híbridas fibra óptica-radio en la banda de 75-110 GHz con baja latencia. Con esto, se analizaron los componentes de la comunicación híbrida fibra ópticaradio en la banda W. En segundo lugar, se realizaron mediciones de los retardos que se generan en cada uno de los elementos en el sistema híbrido de banda W, haciendo la estimación de la latencia general del sistema e identificando fuentes potenciales de demora en los sistemas híbridos de comunicación óptica-RF de alta velocidad de datos. La principal contribución de este trabajo fue el desarrollo de un procedimiento para medir la latencia utilizando radio definida por software (SDR), además de introducir estos sistemas en los enlaces híbridos fibra óptica-radio. Una vez conocido como medir la latencia en un sistema híbrido de fibra óptica-radio, los siguientes objetivos que se desarrollaron fueron: probar un esquema de multiplexación apropiado, como la multiplexación por división de frecuencia ortogonal (OFDM) y la multiplexación por división de frecuencia generalizada (GFDM), para lograr una latencia más baja. A su vez, implementar Multiplexación por división de longitud de onda (WDM) para conocer la latencia y la confiabilidad en cuanto a tasa de error de bits variando la multiplexacion eléctrica y óptica.Doctorad

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression