2,390,540 research outputs found

    Mentoring Programmes as a successful instrument for career development of people with disabilities and disadvantaged

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    [Excerpt] For many years the Mentoring, as a form of support for young people without work experience, is well-known practice. In the past ten years the Mentoring has proved itself as a wide-applied method of support in the career of people with disabilities. A good example of successfully held Mentoring programme in Europe is the “Equal Employment Opportunities: Mentoring and Training for Disabled People and Employers” Project. It is a transnational initiative supported by the “Leonardo da Vinci” Programme of the European Commission. The project includes 3 European countries: Bulgaria, Greece and the UK. The duration of the project was 24 months

    Joint Pilot Design and Uplink Power Allocation in Multi-Cell Massive MIMO Systems

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    This paper considers pilot design to mitigate pilot contamination and provide good service for everyone in multi-cell Massive multiple input multiple output (MIMO) systems. Instead of modeling the pilot design as a combinatorial assignment problem, as in prior works, we express the pilot signals using a pilot basis and treat the associated power coefficients as continuous optimization variables. We compute a lower bound on the uplink capacity for Rayleigh fading channels with maximum ratio detection that applies with arbitrary pilot signals. We further formulate the max-min fairness problem under power budget constraints, with the pilot signals and data powers as optimization variables. Because this optimization problem is non-deterministic polynomial-time hard due to signomial constraints, we then propose an algorithm to obtain a local optimum with polynomial complexity. Our framework serves as a benchmark for pilot design in scenarios with either ideal or non-ideal hardware. Numerical results manifest that the proposed optimization algorithms are close to the optimal solution obtained by exhaustive search for different pilot assignments and the new pilot structure and optimization bring large gains over the state-of-the-art suboptimal pilot design.Comment: 16 pages, 8 figures. Accepted to publish at IEEE Transactions on Wireless Communication

    Pilot Optimization and Channel Estimation for Multiuser Massive MIMO Systems

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    This paper proposes novel pilot optimization and channel estimation algorithm for the downlink multiuser massive multiple input multiple output (MIMO) system with KK decentralized single antenna mobile stations (MSs), and time division duplex (TDD) channel estimation which is performed by utilizing NN pilot symbols. The proposed algorithm is explained as follows. First, we formulate the channel estimation problem as a weighted sum mean square error (WSMSE) minimization problem containing pilot symbols and introduced variables. Second, for fixed pilot symbols, the introduced variables are optimized using minimum mean square error (MMSE) and generalized Rayleigh quotient methods. Finally, for N=1N=1 and N=KN=K settings, the pilot symbols of all MSs are optimized using semi definite programming (SDP) convex optimization approach, and for the other settings of NN and KK, the pilot symbols of all MSs are optimized by applying simple iterative algorithm. When N=KN=K, it is shown that the latter iterative algorithm gives the optimal pilot symbols achieved by the SDP method. Simulation results confirm that the proposed algorithm achieves less WSMSE compared to that of the conventional semi-orthogonal pilot symbol and MMSE channel estimation algorithm which creates pilot contamination.Comment: Accepted in CISS 2014 Conferenc

    Optimal pilot placement for frequency offset estimation and data detection in burst transmission systems

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    In this letter, we address the problem of pilot design for Carrier Frequency Offset (CFO) and data detection in digital burst transmission systems. We consider a quasi-static flat-fading channel. We find that placing half of the pilot symbols at the beginning of the burst and the other half at the end of the burst is optimal for both CFO estimation and data detection. Our findings are based on the Cram´er-Rao bound and on empirical evaluations of the bit error rate for different pilot designs. The equal-preamble-postamble pilot design is shown to provide a significant gain in performance over the conventional preambleonly pilot design

    Channel Estimation and Optimal Pilot Signals for Universal Filtered Multi-Carrier (UFMC) Systems

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    We propose channel estimation algorithms and pilot signal optimization for the universal filtered multi-carrier (UFMC) system based on the comb-type pilot pattern. By considering the least square linear interpolation (LSLI), discrete Fourier transform (DFT), minimum mean square error (MMSE) and relaxed MMSE (RMMSE) channel estimators, we formulate the pilot signals optimization problem by minimizing the estimation MSE subject to the power constraint on pilot tones. The closed-form optimal solutions and minimum MSE are derived for LSLI, DFT, MMSE and RMMSE estimators

    Direct Payments, Independent Living and Mental Health

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    This report is based on a study of the National Pilot to implement direct payments in mental health which took place across five Local Authority sites in England from February 2001 to July 2003. The evaluation used the experiences of the pilot sites as a vehicle through which to understand the factors involved in successfully implementing direct payments in mental health. The evaluation took place in 2002-2003 during the last year of the pilot. This chapter provides an overview of the direct payments and mental health literature and outlines the background to both the National Pilot and the evaluation

    Codes Cross-Correlation Impact on S-curve Bias and Data-Pilot Code Pairs Optimization for CBOC Signals

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    The aim of this paper is to analyze the impact of spreading codes cross-correlation on code tracking performance, and to optimize the data-pilot code pairs of Galileo E1 Open Service (OS) Composite Binary Offset Carrier (CBOC) signals. The distortion of the discriminator function (i.e., S-curve), due to data and pilot spreading codes cross-correlation properties, is evaluated when only the data or pilot components of CBOC signals are tracked, considering the features of the modulation schemes. Analyses show that the S-curve bias also depends on the receiver configuration (e.g., the tracking algorithm and correlator spacing). In this paper, two methods are proposed to optimize the data-pilot code pairs of Galileo E1 OS. The optimization goal is to obtain minimum average S-curve biases when tracking only the pilot components of CBOC signals for the specific correlator spacing. The S-curve biases after optimization processes are analyzed and compared with the un-optimized results. It is shown that the optimized data-pilot code pairs could significantly mitigate the intra-channel (i.e., data and pilot) codes cross-correlation,and then improve the code tracking performance of CBOC signals
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