The Gaussian Multiple Access Diamond Channel

In this paper, we study the capacity of the diamond channel. We focus on the special case where the channel between the source node and the two relay nodes are two separate links with finite capacities and the link from the two relay nodes to the destination node is a Gaussian multiple access channel. We call this model the Gaussian multiple access diamond channel. We first propose an upper bound on the capacity. This upper bound is a single-letterization of an $n$-letter upper bound proposed by Traskov and Kramer, and is tighter than the cut-set bound. As for the lower bound, we propose an achievability scheme based on sending correlated codes through the multiple access channel with superposition structure. We then specialize this achievable rate to the Gaussian multiple access diamond channel. Noting the similarity between the upper and lower bounds, we provide sufficient and necessary conditions that a Gaussian multiple access diamond channel has to satisfy such that the proposed upper and lower bounds meet. Thus, for a Gaussian multiple access diamond channel that satisfies these conditions, we have found its capacity.Comment: submitted to IEEE Transactions on Information Theor

Quality of Bureaucracy and Open-Economy Macro Policies

Bureaucratic quality in terms of the level of corruption varies widely across countries, and is in general slow to evolve relative to the speed with which many economic polices can be implemented such as the imposition of capital controls. In this paper, we study the possibility that quality of bureaucracy may be an important structural determinant of open-economy macro-policies, in particular, the imposition/removal of capital controls, and financial repression. We first derive a model that delivers such a result. Bureaucratic corruption translates into reduced ability by the government to collect tax revenue. Even if capital control/financial repression is otherwise inefficient, as long as the government needs the revenue for public goods provision, it would have to rely more on capital control/financial repression. For all countries for which we can obtain relevant data, we find that more corrupt countries are indeed more likely to impose capital controls, a pattern consistent with the model's prediction. The result of this paper suggests that a premature removal of capital controls mandated by outside institutions could reduce rather than enhance economic efficiency.

The quality of bureaucracy and capital account policies

The extent of bureaucracy varies extensively across countries, but the quality of bureaucracy within a country changes more slowly than economic policies. The authors propose that the quality of bureaucracy may be an important structural determinant of open economy macroeconomic policies - especially the imposition or removal of capital control. In their model, capital controls are an instrument of financial repression. They entail efficiency loss for the economy but also generate implicit revenue for the government. The results show that bureaucratic corruption translates into the government's reduced ability to collect tax revenues. Even if capital controls and financial repression are otherwise inefficient, the government still has to rely on them to raise revenues to provide public goods. Among the countries for which the authors could get relevant data, they find that the more corrupt ones are indeed more likely to impose capital controls, a pattern consistent with the model's prediction. To deal with possible reverse causality, they use the extent of corruption in a country's judicial system, and the degree of democracy, as the instrumental variables for bureaucratic corruption. The instrumental variable regressions show the same result: more corrupt countries are associated with more severe capital controls. The results suggest that as countries develop and improve their public institutions, reducing bureaucratic corruption over time, they will choose to gradually liberalize their capital accounts. Removing capital controls prematurely when forced by outside institutions to do so could reduce rather than improve their economic efficiency.Banks&Banking Reform,Governance Indicators,Environmental Economics&Policies,Economic Theory&Research,National Governance

Multicell Coordinated Beamforming with Rate Outage Constraint--Part I: Complexity Analysis

This paper studies the coordinated beamforming (CoBF) design in the multiple-input single-output interference channel, assuming only channel distribution information given a priori at the transmitters. The CoBF design is formulated as an optimization problem that maximizes a predefined system utility, e.g., the weighted sum rate or the weighted max-min-fairness (MMF) rate, subject to constraints on the individual probability of rate outage and power budget. While the problem is non-convex and appears difficult to handle due to the intricate outage probability constraints, so far it is still unknown if this outage constrained problem is computationally tractable. To answer this, we conduct computational complexity analysis of the outage constrained CoBF problem. Specifically, we show that the outage constrained CoBF problem with the weighted sum rate utility is intrinsically difficult, i.e., NP-hard. Moreover, the outage constrained CoBF problem with the weighted MMF rate utility is also NP-hard except the case when all the transmitters are equipped with single antenna. The presented analysis results confirm that efficient approximation methods are indispensable to the outage constrained CoBF problem.Comment: submitted to IEEE Transactions on Signal Processin

The Contribution Of The Internal And External Dimensions Of Life Experience To The State Of Flow Among Youth: The Case Study Of A Malaysian University

Keadaan aliran didefinisikan sebagai satu keadaan psikologikal di mana seseorang mengalami tahap tumpuan, perasaan seronok, penglibatan dan kawalan diri yang tinggi semasa menjalankan sesuatu aktiviti. Kajian ini meneliti bagaimana kondisi aliran dan jenis aktiviti meramalkan keadaan aliran dalam kalangan orang muda di sebuah universiti di Malaysia. State of flow is defined as a psychological state where individuals experience high level of concentration, enjoyment, involvement and control with the activity that they are engaged in. This study investigated how conditions of flow and types of activities predict state of flow in the daily life of young people in a Malaysian university