A Socio-Economic Analysis of WiMAX

A Socio-Economic Analysis of WiMAX

Abstract:- The paper reports on an analysis of the WiMAX market for the purpose of positioning future contributions of WiMAX standards as part of the WiMAGIC project. The report examines nine key themes that are influencing current and future WiMAX deployments: WiMAX devices, confusion concerning WiMAX capabilities, spectrum allocation, WiMAX as 4G, WiMAX as an emerging country technology, political and regulatory factors, the economic crises, competition (WiMAX vs. LTE), and who are the WiMAX users. We conclude with a final section reviewing the potential market for any future development of WiMAX identifying a number of areas for future research. Subscribe to Complete IEEE Topics and Abstract by Email For more IEEE Topics .

Author:- European Commission’s Seventh Framework.
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Adaptive modulation systems for predicted wireless channels

Adaptive modulation systems for predicted wireless channels
Abstract:- When adaptive modulation is used to counter short-term fading in mobile radio channels, signaling delays create problems with outdated channel state information. The use of channel power prediction will improve the performance of the link adaptation. It is then of interest to take the quality of these predictions into account explicitly when designing an adaptive modulation scheme. We study the optimum design of an adaptive modulation scheme based on uncoded M-quadrature amplitude modulation, assisted by channel prediction for the flat Rayleigh fading channel. The data rate, and in some variants the transmit power, are adapted to maximize the spectral efficiency, subject to average power and bit-error rate constraints. The key issues studied here are how a known prediction error variance will affect the optimized transmission properties, such as the signal-to-noise ratio (SNR) boundaries that determine when to apply different modulation rates, and to what extent it affects the spectral efficiency. This investigation is performed by analytical optimization of the link adaptation, using the statistical properties of a particular, but efficient, channel power predictor. Optimum solutions for the rate and transmit power are derived, based on the predicted SNR and the prediction error variance.
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Author:-Falahati, S. Svensson, A. Ekman, T. Sternad, M.
Dept. of Signals & Syst., Uppsala Univ., Sweden
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Code Shift Keying Impulse Modulation for UWB Communications

Code Shift Keying Impulse Modulation for UWB Communications
Abstract:- In this paper, the system performance of M-ary code shift keying (MCSK) impulse modulation is studied in detail and compared to M-ary pulse position modulation (MPPM) under single- and multi-user scenarios. For that, bounds on the semi- analytic symbol-error rate (SER) expressions are derived and simulation studies are conducted. When practical implementations of MCSK and MPPM are considered, it is shown that MCSK can provide about 2 dB performance gain over MPPM as it reduces the effects of multipath delays on the decision variables by randomizing locations of the transmit pulse.
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Author:-Erkucuk, S.; Dong In Kim; Kyung Sup Kwak
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