Jointly Optimal Spatial Channel Assignment and Power Allocation for MIMO SWIPT Systems

The joint design of spatial channel assignment and power allocation in Multiple Input Multiple Output (MIMO) systems capable of Simultaneous Wireless Information and Power Transfer (SWIPT) is studied. Assuming availability of channel state information at both communications ends, we maximize the harvested energy at the multi-antenna receiver, while satisfying a minimum information rate requirement for the MIMO link. We first derive the globally optimal eigenchannel assignment and power allocation design, and then present a practically motivated tight closed-form approximation for the optimal design parameters. Selected numerical results verify the validity of the optimal solution and provide useful insights on the proposed designs as well as the pareto-optimal rate-energy tradeoff.Comment: 5 pages; 4 figures; accepted to IEEE journal 201

Sum Throughput Maximization in Multi-Tag Backscattering to Multiantenna Reader

Backscatter communication (BSC) is being realized as the core technology for pervasive sustainable Internet-of-Things applications. However, owing to the resource-limitations of passive tags, the efficient usage of multiple antennas at the reader is essential for both downlink excitation and uplink detection. This work targets at maximizing the achievable sum-backscattered-throughput by jointly optimizing the transceiver (TRX) design at the reader and backscattering coefficients (BC) at the tags. Since, this joint problem is nonconvex, we first present individually-optimal designs for the TRX and BC. We show that with precoder and {combiner} designs at the reader respectively targeting downlink energy beamforming and uplink Wiener filtering operations, the BC optimization at tags can be reduced to a binary power control problem. Next, the asymptotically-optimal joint-TRX-BC designs are proposed for both low and high signal-to-noise-ratio regimes. Based on these developments, an iterative low-complexity algorithm is proposed to yield an efficient jointly-suboptimal design. Thereafter, we discuss the practical utility of the proposed designs to other application settings like wireless powered communication networks and BSC with imperfect channel state information. Lastly, selected numerical results, validating the analysis and shedding novel insights, demonstrate that the proposed designs can yield significant enhancement in the sum-backscattered throughput over existing benchmarks.Comment: 17 pages, 5 figures, accepted for publication in IEEE Transactions on Communication

FOREIGN PROFESSIONALS AND DOMESTIC REGULATION

Changes in demographics and patterns of investment in human capital are creating increased scope for international trade in professional services. The scope for mutually beneficial trade is, however, inhibited not only by quotas and discriminatory taxation, but also by domestic regulation -- including a range of qualification and licensing requirements and procedures. To illustrate the nature and implications of these regulatory impediments, this paper presents a detailed description of the regulatory requirements faced in the United States market by four types of Indian professionals: doctors, engineers, architects, and accountants. India is one of the largest exporters of skilled services, and the United States is one of the largest importers of skilled services, so these two countries reflect broader global trends. The paper argues that regulatory discrimination, for example through preferential recognition agreements, has implications both for the pattern of trade and for welfare. It presents some illustrative estimates that suggest the economic cost of regulations may be substantial. The paper concludes by examining how the trade-inhibiting impact of regulatory requirements could be addressed through bilateral and multilateral negotiations.Accreditation; architect; architects; Architecture; barriers to entry; board meeting; candidate; candidates; career; career advancement; Certificate;

Joint Optimization Framework for Operational Cost Minimization in Green Coverage-Constrained Wireless Networks

In this work, we investigate the joint optimization of base station (BS) location, its density, and transmit power allocation to minimize the overall network operational cost required to meet an underlying coverage constraint at each user equipment (UE), which is randomly deployed following the binomial point process (BPP). As this joint optimization problem is nonconvex and combinatorial in nature, we propose a non-trivial solution methodology that effectively decouples it into three individual optimization problems. Firstly, by using the distance distribution of the farthest UE from the BS, we present novel insights on optimal BS location in an optimal sectoring type for a given number of BSs. After that we provide a tight approximation for the optimal transmit power allocation to each BS. Lastly, using the latter two results, the optimal number of BSs that minimize the operational cost is obtained. Also, we have investigated both circular and square field deployments. Numerical results validate the analysis and provide practical insights on optimal BS deployment. We observe that the proposed joint optimization framework, that solves the coverage probability versus operational cost tradeoff, can yield a significant reduction of about $65\%$ in the operational cost as compared to the benchmark fixed allocation scheme.Comment: 30 pages, 15 figures, submitted to IEEE Transactions on Green Communications and Networkin

Joint Optimal Design for Outage Minimization in DF Relay-assisted Underwater Acoustic Networks

This letter minimizes outage probability in a single decode-and-forward (DF) relay-assisted underwater acoustic network (UAN) without direct source-to-destination link availability. Specifically, a joint global-optimal design for relay positioning and allocating power to source and relay is proposed. For analytical insights, a novel low-complexity tight approximation method is also presented. Selected numerical results validate the analysis and quantify the comparative gains achieved using optimal power allocation (PA) and relay placement (RP) strategies.Comment: 5 pages, 2 figures; accepted to IEEE Communications Letters 201

Demand elasticities in international trade : are they really low?

The authors analyze the U.S. demandfor Bangladeshi imports for products restricted under the Multifiber Arrangement. Because Bangladesh is only a small supplier of these products and Latin American and Asian countries can supply close substitutes, the authors expected a high elasticity of demand for Bangladeshi imports, and they found consistently high estimates based on statistically significant coefficients. Their finding accords with trade theorists'prejudice that small countries can essentially behave as price takers, but conflicts with the empirical literature view that demand elasticities are low, rarely exceeding 3 and generally between 1 and 2. The authors'analysis differs from the existing literature in three ways: they derive a set of estimation equations from an explicit, utility-maximization model and use the estimated parameters of the utility function to obtain the Marshallian own-price and cross-price elasticities as well as the income elasticity of demand; they take explicit account of U.S. imports from competitors of Bangladesh, relying directly on competitors'prices; and they use highly disaggregated data that make the unit value of exports a better proxy for price than using aggregated export data commonly used in this literature. The authors outline their theoretical model for deriving their estimated equations in Section 1; preliminarily determine who Bangladesh's competitors are in Section 2; and estimate the demand equation derived in Section 1, and derive the price and income elasticities facing Bangladesh in Section 3.Environmental Economics&Policies,Economic Theory&Research,Markets and Market Access,Payment Systems&Infrastructure,Consumption,Economic Theory&Research,Environmental Economics&Policies,Access to Markets,Markets and Market Access,Consumption