The Approximate Capacity of the MIMO Relay Channel

Capacity bounds are studied for the multiple-antenna complex Gaussian relay channel with t1 transmitting antennas at the sender, r2 receiving and t2 transmitting antennas at the relay, and r3 receiving antennas at the receiver. It is shown that the partial decode-forward coding scheme achieves within min(t1,r2) bits from the cutset bound and at least one half of the cutset bound, establishing a good approximate expression of the capacity. A similar additive gap of min(t1 + t2, r3) + r2 bits is shown to be achieved by the compress-forward coding scheme.Comment: 8 pages, 5 figures, submitted to the IEEE Transactions on Information Theor

Support Recovery of Sparse Signals

We consider the problem of exact support recovery of sparse signals via noisy measurements. The main focus is the sufficient and necessary conditions on the number of measurements for support recovery to be reliable. By drawing an analogy between the problem of support recovery and the problem of channel coding over the Gaussian multiple access channel, and exploiting mathematical tools developed for the latter problem, we obtain an information theoretic framework for analyzing the performance limits of support recovery. Sharp sufficient and necessary conditions on the number of measurements in terms of the signal sparsity level and the measurement noise level are derived. Specifically, when the number of nonzero entries is held fixed, the exact asymptotics on the number of measurements for support recovery is developed. When the number of nonzero entries increases in certain manners, we obtain sufficient conditions tighter than existing results. In addition, we show that the proposed methodology can deal with a variety of models of sparse signal recovery, hence demonstrating its potential as an effective analytical tool.Comment: 33 page

A Study on Thermal Modeling and Heat Load Mitigation for Satellite Electronic Components

Since most of the satellite components are using various EEE (Electrical, Electronic and Electromechanical) parts, the reliability of EEE parts acts very important in the satellite system. There are many factors that influence the reliability of EEE parts in the satellite system. Excessively dissipated heat can cause the failure of EEE parts and consequently, leading to a failure of total satellite system. In this paper, the thermal modeling using nodal network was compared with that using plate modeling to find out which one is the most suitable methodology. For a comparison, KOMPSAT- 1 SAR was modeled by two different modeling and the result was discussed. There was almost no difference in the numerical results between the two modeling methods. However, while it took much more time to perform thermal analysis using the nodal network modeling method, and the debugging was more difficult in the plate modeling method when the error is occurred. The computation time was considerably reduced by developing and implementing the input file format transfer code when using nodal network modeling method. It was found that the nodal network modeling method is suitable for the complicated components, such as SAR or transponder, because of its simple debugging ability. Excessive heat load was expected on some EEE parts of SAR such as high heat-dissipated diodes, transistors, and inductors due to increased power requirements of KOMPSAT-2 satellite system. The methods for the mitigation of heat load were studied through the design change of housing or the layout change of high power parts

The Effect of External and Internal Social Capital of IS project team on Project Success: Multilevel Approach

Knowledge sharing (KS) and organizational citizenship behavior (OCB) among project team members are crucial for project success. The IS project team is a temporary organization and has to produce outcomes in a limited time. We investigate how internal and external social capital (SoC) influence KS and OCB within a team and how OCB and KS affect project success. We also analyze the relationships between the three SoC dimensions through multi-level approach. A statistical testing has not been complete. We will explore both HLM6 and MPLUS for multiple structural equation modeling and introduce a comparative analysis of each set of results. We expect the results of the research can provide project managers with insights on how to encourage project team members to share their knowledge and build teamwork more efficientl

The Global Economic Crisis, Dual Polarization, and Liberal Democracy in South Korea

This paper aims at a theoretical reflection on and an empirical analysis of the relationship between the global economic crisis and liberal democracy in South Korea. For this, we elaborate the concept of dual polarization and construct a model of path analysis which includes such variables as socio-economic and political-ideological cleavage, political party affiliation, ideological orientation, economic (crisis) outlook, and support for an autocratic presidential rule as potential threats to liberal democracy. Descriptively, the paper examines how liberal democracy has unfolded and where South Korea stands today with regard to the quality of her democracy. Analytically, the paper examines where the potential threat to liberal democracy comes from based on a general population survey in Korea from 2014. The major findings of our analysis include: 1) The support for autocratic presidential power is stronger among citizens than among MPs. 2) Political party affiliation, ideological orientation, and economic (crisis) outlook are closely interrelated and significantly affected by the political-ideological cleavage. All independent variables contribute to explaining support for an autocratic presidential rule. 3) Yet there also exists strong support for a democratic regime among both MPs and citizens