Precoder-Aided Iterative Detection Assisted Multilevel Coding and Three-Dimensional EXIT-Chart Analysis

A novel three-dimensional (3D) EXIT chart is developed for investigating the iterative behaviour of Multilevel Coding (MLC) invoking Multistage Decoding (MSD). The extrinsic information transfer characteristics of both the symbol-to-bit demapper used and those of the differentprotection constituent decoders suggest that potential improvements can be achieved by appropriately designing the demapper. The proposed 3D EXIT chart is then invoked for studying the precoder-aided multilevel coding scheme employing both MSD and Parallel Independent Decoding (PID) for communicating over AWGN and uncorrelated Rayleigh fading channels with the aid of 8PSK modulation. At BER=10?5, the precoder was capable of enhancing the achievable Eb/N0 performance by 0.5dB to 2.5dB over AWGN and Rayleigh channels, respectively

Assessing statistical significance of periodogram peaks

The least-squares (or Lomb-Scargle) periodogram is a powerful tool which is used routinely in many branches of astronomy to search for periodicities in observational data. The problem of assessing statistical significance of candidate periodicities for different periodograms is considered. Based on results in extreme value theory, improved analytic estimations of false alarm probabilities are given. They include an upper limit to the false alarm probability (or a lower limit to the significance). These estimations are tested numerically in order to establish regions of their practical applicability.Comment: 7 pages, 6 figures, 1 table; To be published in MNRA

Luby Transform Coding Aided Bit-Interleaved Coded Modulation for the Wireless Internet

Bit-Interleaved Coded Modulation using Iterative Decoding (BICM-ID) is amalgamated with Luby Transform (LT) coding. The resultant joint design of the physical and data link layer substantially improves the attainable Bit Error Rate (BER) performance. A Cyclic Redundancy Check (CRC) combined with a novel Log-Likelihood Ratio (LLR) based packet reliability estimation method is proposed for the sake of detecting and disposing of erroneous packets. Subsequently, bit-by-bit LT decoding is proposed, which facilitates a further BER improvement at a lower number of BICM-ID iterations. Finally, we revisit the pseudo random generator function used for designing the LT generator matrix

Standards dynamics and industrial organization in the mobile telecom sector

Purpose - The purpose of this mainly conceptual paper is to analyze key changes in the institutional setting for standardization and to discuss what they indicate about further developments of the mobile sector. The intention is that this conceptual analysis will complement and contextualize the analysis of Nordic players found in the other papers of this special issue. Design/methodology/approach - The paper is concerned with issues of industrial organization. The paper presents a treatment of industrial dynamics in them mobile telecom sector and the changing role of standards in it. We approach the substantial changes in the mobile telecom sector, focusing on the correspondence of the changes in the standards system to overall industry dynamics. Empirical information from the Symbian case is used to illustrate the hypothesis of standardization process and of the industry at large. Findings - The paper identifies changing patterns in the organization of technological standardization which represents a microcosm of the larger reorganization of the sector. Nordic actors, whose present position owes much to success in linking capabilities to sequential mobile standards. The paper draws out implications of the limits to "intergenerational leveraging" in standards. Originality/value - The major contribution of the paper is to focus on changes in the organization of the standardization process in order to discuss the industrial dynamics of an industry which is undergoing a period of rapid change. Its reference to industrial dynamics perspective allows it to link the literature on dominant design to the field of standards research

Downlink Steered Space-Time Spreading Assisted Generalised Multicarrier DS-CDMA Using Sphere-Packing-Aided Multilevel Coding

This paper presents a novel generalised Multi-Carrier Direct Sequence Code Division Multiple Access (MC DS-CDMA) system invoking smart antennas for improving the achievable performance in the downlink, as well as employing multi-dimensional Sphere Packing (SP) modulation for increasing the achievable diversity product. In this contribution, the MC DS-CDMA transmitter considered employs multiple Antenna Arrays (AA) and each of the AAs consists of several antenna elements. Furthermore, the proposed system employs both time- and frequency- (TF) domain spreading for extending the achievable capacity, when combined with a novel user-grouping technique for reducing the effects of Multiuser Interference (MUI). Moreover, in order to further enhance the system’s performance, we invoke a MultiLevel Coding (MLC) scheme, whose component codes are determined using the so-called equivalent capacity based constituent-code rate-calculation procedure invoking a 4-dimensional bit-to-SP-symbol mapping scheme. Our results demonstrate an approximately 3.8 dB Eb/N0 gain over an identical throughput scheme dispensing with SP modulation at a BER of 10?5

Risk-cost optimization of buried pipelines using subset simulation

On the basis of time-dependent reliability analysis, a computational framework called subset simulation (SS) has been applied for risk-cost optimization of flexible underground pipeline networks. SS can provide better resolution for rare failure events that are commonly encountered in pipeline engineering applications. Attention in this work is devoted to scrutinize the robustness of SS in risk-cost optimization of pipelines. SS is first employed to estimate the reliability of flexible underground pipes subjected to externally applied loading and material corrosion. Then SS is extended to determine the intervention year for maintenance and to identify the most appropriate renewal solution and renewal priority by minimizing the risk of failure and whole life-cycle cost. The efficiency of SS compared to genetic algorithm has been demonstrated by numerical studies with a view to prevent unexpected failure of flexible pipes at minimal cost by prioritizing maintenance based on failure severity and system reliability. This paper shows that SS is a more robust method in the decision-making process of reliability-based management for underground pipeline networks

Strategies for managing the structural and dynamic consequences of project complexity

In this paper we propose a theoretical framework that highlights the most important consequences of complexity for the form and evolution of projects, and use it to develop a typology of project complexity. This framework also enables us to deepen the understanding of how knowledge production and flexibility strategies enable project participants to address complexity. Based on this understanding, we advance a number of propositions regarding the strategies that can be most effective for different categories of complexity. We hope these results will help integrate various strands in the research on project complexity, and provide a roadmap for further research on the strategies for addressing it

Spherical Tin Oxide, SnO2 Particles Fabricated via Facile Hydrothermal Method for Detection of Mercury (II) Ions.

Smooth-surface spherical tin oxide particles were fabricated via hydrothermal processing route. X-ray diffraction (XRD) revealed that the particles consisted of the rutile phase of SnO2 with tetragonal structure. The spherical morphology was realized with the aid of ammonia. The aggregation of SnO2 particles could be avoided by adjusting the concentration of tin (II) chloride. Bare glassy carbon electrode (GCE) was modified with the hydrothermally prepared SnO2 particles to detect the presence of mercury (II) ions (Hg2+), in the presence of potassium chloride (KCl) as a supporting electrolyte. GCE modified with the spherical SnO2 particles that possessed small crystallite size and smooth surface exhibited significantly enhanced oxidative and reductive current of Hg2+ during cyclic voltammetry compared with its bare counterpart. The reductive current was observed to increase by two fold and the detection limit of 75 nM for Hg 2+ was achieved. This suggests that SnO2 particles are a promising chemical sensor for the detection of Hg2+ in natural waters

Faktor-faktor Yang Mempengaruhi Mahasiswa Menggunakan Mobil Ke Kampus Berdasarkan Teori Perilaku Terencana

Transportasi memiliki peranan penting dalam USAha meningkatkan kualitas hidup manusia. Seiring berjalannya waktu, transportasi mengalami perkembangan. Hal ini berdampak pada bertambahnya jumlah kendaraan yang beredar yang disebut juga dengan motorisasi. Fenomena serupa juga terjadi di kampus dimana terdapat peningkatan jumlah mobil yang beredar di kampus. Pihak kampus dapat menerapkan Manajemen Transportasi Kampus untuk mengatasinya, namun akan lebih efektif apabila dapat diketahui faktor yang mempengaruhi mahasiswa untuk lebih memilih menggunakan mobil.Penelitian ini bertujuan untuk mengetahui faktor apa yang paling mempengaruhi mahasiswa menggunakan mobil ke kampus berdasarkan Teori Perilaku Terencana dengan mengesampingkan faktor biaya dan waktu. Responden adalah mahasiswa yang secara rutin menggunakan mobil ke kampus. Data yang diperoleh selanjutnya akan diolah dengan bantuan program Structural Equation Modelling (SEM). Hasil penelitian menunjukan bahwa diantara ketiga faktor dari Teori Perilaku Terencana, diketahui bahwa perceived behavioral control adalah faktor yang paling mempengaruhi intensi yang nantinya akan berpengaruh pada behavior