Applications of Soft Computing in Mobile and Wireless Communications

Soft computing is a synergistic combination of artificial intelligence methodologies to model and solve real world problems that are either impossible or too difficult to model mathematically. Furthermore, the use of conventional modeling techniques demands rigor, precision and certainty, which carry computational cost. On the other hand, soft computing utilizes computation, reasoning and inference to reduce computational cost by exploiting tolerance for imprecision, uncertainty, partial truth and approximation. In addition to computational cost savings, soft computing is an excellent platform for autonomic computing, owing to its roots in artificial intelligence. Wireless communication networks are associated with much uncertainty and imprecision due to a number of stochastic processes such as escalating number of access points, constantly changing propagation channels, sudden variations in network load and random mobility of users. This reality has fuelled numerous applications of soft computing techniques in mobile and wireless communications. This paper reviews various applications of the core soft computing methodologies in mobile and wireless communications

Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

Small satellite systems enable whole new class of missions for navigation, communications, remote sensing and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft which opens the door to new applications. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this paper, we present the various researches being conducted in the small satellite community for implementing inter-satellite communications based on the Open System Interconnection (OSI) model. This paper also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications Surveys and Tutorial

Effect of multiuser interference on subscriber location in CDMA networks

The last few years have witnessed an ever growing interest in the field of mobile location systems for cellular systems. The motivation is the series of regulations passed by Federal Communications Commission, requiring that wireless service providers support a mobile telephone callback feature and cell site location mechanism. A further application of the location technology is in the rapidly emerging field of intelligent transportation systems, which are intended to enhance highway safety, location based billing etc. Many of the existing location technologies use GPS and its derivatives which require a specialized subscriber equipment. This is not feasible for popular use, as the cost of such equipments is very high. Hence, for a CDMA network, various methods have been studied that use the cellular network as the sole means to locate the mobile station (MS), where the estimates are derived from the signal transmitted by the MS to a set of base station\u27s (BS) This approach has the advantage of requiring no modifications to the subscriber equipment. While subscriber location has been previously studied for CDMA networks, the effect of multiple access interference has been ignored. In this thesis we investigate the problem of subscriber location in the presence of multiple access interference. Using MATLAB as a simulation tool, we have developed an extensive simulation technique which measures the error in location estimation for different network and user configurations. In our studies we include the effects of log-normal shadow and Rayleigh fading. We present results that illustrate the effects of varying shadowing losses, number of BS\u27s involved in position location, early-late discriminator offset and cell sizes in conjunction with the varying number of users per cell on the accuracy of radiolocation estimation

Energy Efficient Cooperative Mobile Sensor Network

Ph.DDOCTOR OF PHILOSOPH

Radio network planning and optimisation for WCDMA

The present thesis introduces the radio network planning process and optimisation for WCDMA (FDD mode), as defined by 3GPP. This thesis consists of three parts: modelling and tools for radio network planning, process for pre-operational network control and optimisation for the operational network. General challenges to face in 3G network control are based on the fact that many issues are interconnected and should be simultaneously considered, such as Planning means not only to meet current status and demands, but the solution should also comply with the future requirements by providing an acceptable development path. Traffic modelling is not only the question about the total amount of traffic growth, but also the question about the future service distribution and performance demands. All CDMA systems have a relation between capacity and coverage. Consequently, the network planning itself is not only based on propagation estimation but also on the interference situation in the network. Ideally, site selection consideration will be done based on the network analysis with planned load and traffic/service portfolio, taking possible co-siting constraints into account. Provision of multiple services and seamless management of at least two multiple access systems require rapid evolution of the management tools and processes. The network performance in terms of capacity, quality, and implementation and operational costs forms a multidimensional space. Operators' task will be to convert the business strategy to an operating point in the performance space in a cost efficient manner. The contribution of this thesis in terms of modelling and tools is as follows: Improvement of the accuracy of radio link budget by introducing power control headroom (also called fast fading margin). Improvement of loading equation by introducing a transmit power increase term. Development of theory and modelling for a planning tool capable of multi-service and multi-carrier interference, capacity and coverage analysis. Development and implementation an interface taking into account the true traffic distribution (not uniform) and terminal speed. In the area of pre-operational planning process the contribution of this thesis is as follows: Development of dimensioning methodology for multi-service network site density estimation, utilising the modelling of power control headroom, transmit power increase, soft handover and Eb/N0. Development of radio network planning process for multi-service environment including capacity and coverage evaluation for a given traffic mixture, quality and area requirements. Analysis of means to improve radio network performance with Mast Head Amplifier (MHA), diversity reception, sectorisation and proper antenna selection. In the area of optimisation of the operational network the contribution of this thesis is as follows: Definition for optimisation target in the case of 3G. The optimisation will be capacity-quality trade-off management instead of plain quality improvement process. Introduction of Self Organizing Map (SOM) in the analysis of cellular networks. Analysis of the applicability of SOM in WCDMA cellular network optimisation. Introduction of SOM based applications to support network capacity-quality trade-off management. It is worth noting that process and methods described in this work are not limited to 3G systems with WCDMA radio access technology, but they are applicable to other CDMA standards as well.reviewe

Quantum-aided multi-user transmission in non-orthogonal multiple access systems

With the research on implementing a universal quantum computer being under the technological spotlight, new possibilities appear for their employment in wireless communications systems for reducing their complexity and improving their performance. In this treatise, we consider the downlink of a rank-deficient, multi-user system and we propose the discrete-valued and continuous-valued Quantum-assisted Particle Swarm Optimization (QPSO) algorithms for performing Vector Perturbation (VP) precoding, as well as for lowering the required transmission power at the Base Station (BS), while minimizing the expected average Bit Error Ratio (BER) at the mobile terminals. We use the Minimum BER (MBER) criterion. We show that the novel quantum-assisted precoding methodology results in an enhanced BER performance, when compared to that of a classical methodology employing the PSO algorithm, while requiring the same computational complexity in the challenging rank-deficient scenarios, where the number of transmit antenna elements at the BS is lower than the number of users. Moreover, when there is limited Channel State Information (CSI) feedback from the users to the BS, due to the necessary quantization of the channel states, the proposed quantum-assisted precoder outperforms the classical precoder

Cost based optimization for strategic mobile radio access network planning using metaheuristics

La evolución experimentada por las comunicaciones móviles a lo largo de las últimas décadas ha sido motivada por dos factores principales: el surgimiento de nuevas aplicaciones y necesidades por parte del usuario, así como los avances tecnológicos. Los servicios ofrecidos para términales móviles han evolucionado desde el clásico servicio de voz y mensajes cortos (SMS), a servicios más atractivos y por lo tanto con una rápida aceptación por parte de usuario final como, video telephony, video streaming, online gaming, and the internet broadband access (MBAS). Todos estos nuevos servicios se han convertido en una realidad gracias a los avances técnologicos, avances tales como nuevas técnicas de acceso al medio compartido, nuevos esquemas de codificiación y modulación de la información intercambiada, sistemas de transmisión y recepción basados en múltiples antenas (MIMO), etc. Un aspecto importante en esta evolución fue la liberación del sector a principios de los años 90, donde la función reguladora llevado a cabo por las autoridades regulatorias nacionales (NRA) se ha antojado fundamental. Uno de los principales problemas tratados por la NRA espcífica de cada nación es la determinación de los costes por servicios mayoristas, esto es los servicios entre operadores de servicios móvilles, entre los que cabe destacar el coste por terminación de llamada o de inteconexión. El servicio de interconexión hace posible la comunicación de usuarios de diferente operadores, así como el acceso a la totalidad de servicios, incluso a aquellos no prestados por un operador en concreto gracias al uso de una red perteneciente a otro operador, por parte de todos los usuarios. El objetivo principal de esta tesis es la minimización de los costes de inversión en equipamiento de red, lo cual repercute en el establecimiento de las tarifas de interconexión como se verá a lo largo de este trabajo. La consecución de dicho objetivo se divide en dos partes: en primer lugar, el desarrollo de un conjunto de algoritmos para el dimesionado óptimo de una red de acceso radio (RAN) para un sistema de comunicaciones móvilles. En segundo lugar, el diseño y aplicación de algoritmos de optimización para la distribución óptima de los servicios sobre el conjunto de tecnologías móviles existentes (OSDP). El modulo de diseño de red proporciona cuatro algoritmos diferenciados encargados del dimensionado y planificación de la red de acceso móvil. Estos algoritmos se aplican en un entorno multi-tecnología, considerando sistemas de segunda (2G), tercera (3G) y cuarta (4G) generación, multi-usuario, teniendo en cuenta diferentes perfiles de usuarios con su respectiva carga de tráfico, y multo-servicio, incluyendo voz, servicios de datos de baja velocidad (64-144 Kbps), y acceso a internet de banda ancha móvil. La segunda parte de la tesis se encarga de distribuir de una manera óptima el conjunto de servicios sobre las tecnologías a desplegar. El objetivo de esta parte es hacer un uso eficiente de las tecnologías existentes reduciendo los costes de inversión en equipamiento de red. Esto es posible gracias a las diferencias tecnológicas existente entre los diferentes sistemas móviles, que hacen que los sistemas de segunda generación sean adecuados para proporcionar el servicio de voz y mensajería corta, mientras que redes de tercera generación muestran un mejor rendimiento en la transmisión de servicios de datos. Por último, el servicio de banda ancha móvil es nativo de redes de última generadón, como High Speed Data Acces (HSPA) y 4G. Ambos módulos han sido aplicados a un extenso conjunto de experimentos para el desarrollo de análisis tecno-económicos tales como el estudio del rendimiento de las tecnologías de HSPA y 4G para la prestación del servicio de banda ancha móvil, así como el análisis de escenarios reales de despliegue para redes 4G que tendrán lugar a partir del próximo año coinicidiendo con la licitación de las frecuencias en la banda de 800 MHz. Así mismo, se ha llevado a cabo un estudio sobre el despliegue de redes de 4G en las bandas de 800 MHz, 1800 MHz y 2600 MHz, comparando los costes de inversión obtenidos tras la optimización. En todos los casos se ha demostrado la mejora, en términos de costes de inversión, obtenida tras la aplicación de ambos módulos, posibilitando una reducción en la determinación de los costes de provisión de servicios. Los estudios realizados en esta tesis se centran en la nación de España, sin embargo todos los algoritmos implementados son aplicables a cualquier otro país europeo, prueba de ello es que los algoritmos de diseño de red han sido utilizados en diversos proyectos de regulación