412 research outputs found

    CogCell: Cognitive Interplay between 60GHz Picocells and 2.4/5GHz Hotspots in the 5G Era

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    Rapid proliferation of wireless communication devices and the emergence of a variety of new applications have triggered investigations into next-generation mobile broadband systems, i.e., 5G. Legacy 2G--4G systems covering large areas were envisioned to serve both indoor and outdoor environments. However, in the 5G-era, 80\% of overall traffic is expected to be generated in indoors. Hence, the current approach of macro-cell mobile network, where there is no differentiation between indoors and outdoors, needs to be reconsidered. We envision 60\,GHz mmWave picocell architecture to support high-speed indoor and hotspot communications. We envisage the 5G indoor network as a combination of-, and interplay between, 2.4/5\,GHz having robust coverage and 60\,GHz links offering high datarate. This requires an intelligent coordination and cooperation. We propose 60\,GHz picocellular network architecture, called CogCell, leveraging the ubiquitous WiFi. We propose to use 60\,GHz for the data plane and 2.4/5GHz for the control plane. The hybrid network architecture considers an opportunistic fall-back to 2.4/5\,GHz in case of poor connectivity in the 60\,GHz domain. Further, to avoid the frequent re-beamforming in 60\,GHz directional links due to mobility, we propose a cognitive module -- a sensor-assisted intelligent beam switching procedure -- which reduces the communication overhead. We believe that the CogCell concept will help future indoor communications and possibly outdoor hotspots, where mobile stations and access points collaborate with each other to improve the user experience.Comment: 14 PAGES in IEEE Communications Magazine, Special issue on Emerging Applications, Services and Engineering for Cognitive Cellular Systems (EASE4CCS), July 201

    Design and Development of HiperLAN/2 WLANs Based Multiwavelet Signals using Adaptive Antennas Algorithm

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    In this paper a simple adaptive antenna idea, consisting of multiple independent omni directional receiver antennas and the ZF (Zero Forcing) algorithm for the adaptive signal processing, is applied to the HiperLAN/2 WLANs based Orthogonal Frequency-Division Multiplexing OFDM, Discrete Multiwavelet Transform (DMWT) and its performance is evaluated at link level. MATLAB modeling demonstrated that the performance with adaptive receiver antennas has a remarkable degradation in the packet (PDU or PSDU) error rate (PER) compared to without using adaptive receiver antennas due to the considerable channel models. With adaptive receiver antennas, Carrier-to-Noise Ratio (C/N) improvement compared to without using adaptive receiver antennas is achieved. The performance of the system can more improve by increasing the number of antennas at receiver. Keywords: Network, HiperLAN/2, Adaptive, OFDM, DMWT, IDMWT

    Review on NEXT Generation Technologies of Wireless Communication

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    Cellular communication has brought in an unparalleled revolution in the field of communication during the past two decades. The mobile communication industry growth has surpassed growth of all other fields. Even o ur own country is not left behind. The number of mobile subscribers in the country rose to over 9 11 m in Mar 201 2 . 3G system has been introduced in line with other countries. Talks have started about 4G / 5G. The implementation of 4G /5G will most probably be the ultimate goal in the field of communication

    ACUTA Journal of Telecommunications in Higher Education

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    In This Issue 5G\u27s Promise: 1,000 x Capacity, 1,000 x Challenges Higher-Speed WLANs About to Emerge State of the Residential Network 2013 LTE: The Next Wave of Wireless Evolution The 10 Most Costly Pitfalls of DAS Deployment and How to Avoid Them DAS on Campus: Solutions for Wireless Service Decision Criteria for Selecting a Wireless lntrusion Prevention System lnstitutional Excellence Award President\u27s Message From the CE

    Técnicas de equalização para MIMO massivo com amplificação não linear

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    The dawn of the new generation of mobile communications and the trafic explosion that derives from its implementation pose great challenge. The milimeter wave band and the use of massive number of antennas are technologies which, when combined, allow the transmission of high data rate, functioning in zones of the electromagnetic spectrum that are less explored and with capability of allocation of dozens of GHz of bandwidth. In this dissertation we consider a massive MIMO millimeter wave system employing a hybrid architecture, i.e., the number of transmit and receive antennas are lower than the number of radio frequency chains. As consequence, the precoder and equalizers should be designed in both digital and analog domains. In the literature, most of the proposed hybrid beamforming schemes were evaluated without considering the effects of nonlinear amplifications. However, these systems face non-avoidable nonlinear effects due to power amplifiers functioning in nonlinear regions. The strong nonlinear effects throughout the transmission chain will have a negative impact on the overall system performance and thus its study and the design of equalizers that take into account these effects are of paramount importance. This dissertation proposes a hybrid iterative equalizer for massive MIMO millimeter wave SC-FDMA systems. The user terminals have low complexity, just equipped with analog precoders based on average angle of departure, each with a single radio frequency chain. At the base station it is designed an hybrid analog-digital iterative equalizer with fully connected architecture in order to eliminate both the multi-user interference and the nonlinear distortion caused by signal amplification during the transmission. The equalizer is optimized by minimizing the bit error rate, which is equivalent to minimize the mean square error rate. The impact of the saturation threshold of the amplifiers in the system performance is analysed, and it is demonstrated that the iterative process can efficiently remove the multi-user interference and the distortion, improving the overall system performance.O surgimento de uma nova geração de comunicaçÔes mĂłveis e a explosĂŁo de trĂĄfego que advĂ©m da sua implementação apresenta grandes desafios. A banda de ondas milimĂ©tricas e o uso massivo de antenas sĂŁo tecnologias que, combinadas, permitem atingir elevadas taxas de transmissĂŁo, funcionando em zonas do espectro electromagnĂ©tico menos exploradas e com capacidade de alocação de dezenas de GHz para largura de banda. Nesta dissertação foi considerado um sistema de MIMO massivo de ondas milimĂ©tricas usando uma arquitectura hĂ­brida, i.e., o nĂșmero de antenas para transmissĂŁo e recepção Ă© menor que o nĂșmero de cadeias de radiofrequĂȘncia. Consequentemente, o prĂ©-codificador e equalizadores devem ser projectados nos domĂ­nios digital e analĂłgico. Na literatura, a maioria dos esquemas hĂ­bridos de beamforming sĂŁo avaliados sem ter em conta os efeitos de nĂŁo linearidade da amplificação do sinal. No entanto, estes sistemas sofrem inevitavelmente de efeitos nĂŁo lineares devido aos amplificadores de potĂȘncia operarem em regiĂ”es nĂŁo lineares. Os fortes efeitos das nĂŁo-linearidades ao longo da cadeia de transmissĂŁo tĂȘm um efeito nefasto no desempenho do sistema e portanto o seu estudo e projecto de equalizadores que tenham em conta estes efeitos sĂŁo de extrema importĂąncia. Esta dissertação propĂ”e um equalizador hĂ­brido para sistemas baseados em ondas milimĂ©tricas para MIMO massivo com modulação SC-FDMA. Os terminais de utilizador possuem baixa complexidade, equipados apenas com prĂ©-codificadores analĂłgicos baseados no Ăąngulo mĂ©dio de partida, cada um com uma Ășnica cadeia de radiofrequĂȘncia. Na estação base Ă© projectado um equalizador iterativo hĂ­brido analĂłgico-digital com arquitectura completamente conectada de modo a eliminar a interferencia multi-utilizador e a distorção causada pela amplificação do sinal aquando da transmissĂŁo. O equalizador Ă© optimizado minimizando a taxa de erro de bit, o que Ă© equivalente a minimizar a taxa de erro quadrĂĄtico mĂ©dio. O impacto do limiar de saturação dos amplificadores no desempenho do sistema Ă© analisado, e Ă© demonstrado que o processo iterativo consegue eliminar de modo eficiente a interferĂȘncia multi-utilizador e a distorção, melhorando o desempenho do sistema.Mestrado em Engenharia EletrĂłnica e TelecomunicaçÔe

    Improving Frequency Reuse and Cochannel Interference Coordination in 4G HetNets

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    This report describes my M.A.Sc. thesis research work. The emerging 4th generation (4G) mobile systems and networks (so called 4G HetNets) are designed as multilayered cellular topology with a number of asymmetrically located, asymmetrically powered, self-organizing, and user-operated indoor small cell (e.g., pico/femto cells and WLANs) with a variety of cell architectures that are overlaid by a large cell (macro cell) with some or all interfering wireless links. These designs of 4G HetNets bring new challenges such as increased dynamics of user mobility and data traffic trespassing over the multi-layered cell boundaries. Traditional approaches of radio resource allocation and inter-cell (cochannel) interference management that are mostly centralized and static in the network core and are carried out pre-hand by the operator in 3G and lower cellular technologies, are liable to increased signaling overhead, latencies, complexities, and scalability issues and, thus, are not viable in case of 4G HetNets. In this thesis a comprehensive research study is carried out on improving the radio resource sharing and inter-cell interference management in 4G HetNets. The solution strategy exploits dynamic and adaptive channel allocation approaches such as dynamic and opportunistic spectrum access (DSA, OSA) techniques, through exploiting the spatiotemporal diversities among transmissions in orthogonal frequency division multiple access (OFDMA) based medium access in 4G HetNets. In this regards, a novel framework named as Hybrid Radio Resource Sharing (HRRS) is introduced. HRRS comprises of these two functional modules: Cognitive Radio Resource Sharing (CRRS) and Proactive Link Adaptation (PLA) scheme. A dynamic switching algorithm enables CRRS and PLA modules to adaptively invoke according to whether orthogonal channelization is to be carried out exploiting the interweave channel allocation (ICA) approach or non-orthogonal channelization is to be carried out exploiting the underlay channel allocation (UCA) approach respectively when relevant conditions regarding the traffic demand and radio resource availability are met. Benefits of CRRS scheme are identified through simulative analysis in comparison to the legacy cochannel and dedicated channel deployments of femto cells respectively. The case study and numerical analysis for PLA scheme is carried out to understand the dynamics of threshold interference ranges as function of transmit powers of MBS and FBS, relative ranges of radio entities, and QoS requirement of services with the value realization of PLA scheme.1 yea
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