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This study presents a comprehensive analysis to highlight advantages and disadvantages, in terms of channel capacity and computational complexity (CC), of a so-called clustered-orthogonal frequency division multiplexing (OFDM) scheme for power line communication (PLC) technologies for access networks. By taking into account filtering, decimation and upsampling techniques, the implementations of two transmitter schemes, named 𝒫(·)-I and 𝒫(·)-II, and three receivers ones, named 𝒬(·)-I, 𝒬(·)-II and 𝒬(·)-III, that can be easily derived from the hermitian symmetric OFDM (HS-OFDM) scheme are discussed. Numerical results show that the clustered-OFDM schemes based on HS-OFDM provide the same bit-error-rate performance as that of HS-OFDM, double sideband-OFDM and single sideband-OFDM. Also, clustered-OFDM based on the combination of 𝒬(·)-II and 𝒬(·)-III offers the lowest CC for both baseband and passband data communications. Further, it is demonstrated that the clustered-OFDM schemes can trade off channel capacity for CC, which can give rise to low-priced transceivers for PLC technologies. Finally, a comparative analysis of clustered-OFDM and orthogonal frequency division multiple access (OFDMA) points out the scenarios in which clustered-OFDM can be competitive if the complexity of the OFDM transceiver is a primary consideration.

This article reviews results from the literature illustrating the bottlenecks and tradeoffs of integrated sensing and communication (ISAC) through the lens of information theory, thus offering a distinct perspective compared to recent works that focus on signal processing, wireless communications, or other related overviews. Different models and scenarios are considered and compared. For example, scenarios where radar sensing is performed at the communication and radar transmitter (mono-static ISAC) and scenarios where the radar receiver differs from the radar transmitter (called bi-static radar). Similarly, we discuss ISAC bottlenecks and tradeoffs both in slowly-varying environments where the main sensing target is described by a single parameter and accordingly, sensing performance is described by detection error probabilities, as well as in fast-varying environments, where the sensing targets are described by vectors and thus vector-valued performance measures such as average distortions like mean-squared errors are used to determine sensing performances. This overview article further also considers limitations and opportunities in network ISAC environments, such as collaborative or interactive sensing, and the influence of secrecy and privacy requirements on ISAC systems, a line of research that has received growing interest over the last few years. For all these scenarios, we provide and discuss precise models and their limitations and provide either bounds or full characterizations of the fundamental information-theoretic performance limits of these systems. Further extensions as well as important open research directions are also discussed.

The integration of ad hoc device-to-device (D2D) communications and open-access small cells can result in a networking paradigm called hybrid the ad hoc network, which is particularly promising in delivering delay-tolerant data. The capacity-delay performance of hybrid ad hoc networks has been studied extensively under a popular framework called scaling law analysis. These studies, however, do not take into account aspects of interference accumulation and queueing delay and, therefore, may lead to over-optimistic results. Moreover, focusing on the average measures, existing works fail to give finer-grained insights into the distribution of delays. This paper proposes an alternative analytical framework based on queueing theoretic models and physical interference models. We apply this framework to study the capacity-delay performance of a collaborative cellular D2D network with coverage sensing and two-hop relay. The new framework allows us to fully characterize the delay distribution in the transform domain and pinpoint the impacts of coverage sensing, user and base station densities, transmit power, user mobility and packet size on the capacity-delay trade-off. We show that under the condition of queueing equilibrium, the maximum throughput capacity per device saturates to an upper bound of 0.7239 λ b / λ u bits/s/Hz, where λ b and λ u are the densities of base stations and mobile users, respectively.

Theoretically, trade capacity building should contribute to export-led growth and support liberal economic policies. Unfortunately, it often fails to meet this ideal due to resource misallocation, misplaced focus on existing obligations, and donor-driven implementation. This article presents a formal theory of political-economic problems in trade capacity building. I analyze trade liberalization as a repeated game with imperfect public monitoring between a developed and developing country. Modeling trade capacity building as an investment by the developed country, I show that it suffers from two problems. First, the need to enforce trade liberalization drives resource misallocation: costly projects are implemented only to build commitment capacity while others are not implemented because they encourage protectionism. Second, donor interests distort trade capacity building. Counterintuitively, if the donor can seek compensation from the recipient when it violates international trade law, it sometimes refuses to invest in low-cost trade capacity building while funding projects that hurt the recipient.

An independent evaluation of the World Bank??s extensive support to developing countries on trade issues between 1987 and 2004. The study assesses the development effectiveness of World Bank trade-related advocacy, capacity-building, lending and research. It examines the extent to which the Bank??s policies and assistance have met its stated objectives in the area of trade and makes recommendations to strengthen the effectiveness of future Bank trade assistance.

To determine the capacity of distributed wireless networks (i.e., ad hoc networks), the random access transport capacity was proposed as the average maximum rate of successful end-to-end transmission in the distance. In this article, we consider the random access transport capacity for multihop relaying to find the end-to-end throughput of a wireless ad hoc network, where each node relays the signal using an amplify-and-forward (AF) strategy. In particular, we analyze the exact outage probability for multihop AF relaying in the presence of both co-channel interference and thermal noise, where interferers are spatially distributed following a Poisson distribution. In our numerical results, it is observed that the maximum random access transport capacity is achieved at a specific spatial density of transmitting nodes due to the throughput-reliability tradeoff as the number of transmitting nodes (=interferers) increases. We compute the optimal spatial density of transmitting nodes that maximize their random access transport capacity. As a result, we can obtain the actual random access transport capacity of multihop AF relaying and predict the maximum number of transmitting nodes per unit area to maximize their performance.

Trade can be a powerful engine for economic growth, poverty reduction, and development. However, harnessing the power of trade is often difficult for developing countries, particularly the least developed countries, because of supply-side domestic constraints (lack of trade-related infrastructure and capacity). The Aid for Trade Initiative was launched to address these constraints. This paper sets forth strategies to identify the most binding constraints to trade expansion so countries and donors can channel resources toward reforms and projects that have the largest effect. It shows that the four most common objectives of aid-for-trade projects (increasing trade, diversifying exports, maximizing the linkages with the domestic economy, and increasing adjustment capacity) have the potential to boost growth and reduce poverty in developing countries. However, the potential of trade may not be realized as developing countries often face binding constraints that prevent them from turning trade opportunities into trade, and trade into growth. First, they face difficulties turning trade opportunities into trade flows because of capacity constraints and lack of adequate trade-related infrastructure. Second, some domestic constraints choke the impact of trade expansion on economic growth. The paper focuses on the first set of constraints and presents various diagnostic tools available to identify them. These tools often pinpoint a long list of constraints. As all constraints cannot be addressed simultaneously, there is a need to identify the most binding ones in order to prioritize reforms. The paper suggests combining the different diagnostic tools in an appropriate framework to achieve this prioritization. An adaptation of the growth diagnostics— originally developed by Hausmann et al. (2005) for guiding growth strategies—can be such a framework. By shifting the focus from growth to trade, this framework can be readily adapted by local authorities and development practitioners.

This paper exploits India's rapid, comprehensive, and externally imposed trade reform to establish a causal link between changes in tariffs and firm productivity. Pro-competitive forces, resulting from lower tariffs on final goods, as well as access to better inputs, due to lower input tariffs, both appear to have increased firm-level productivity, with input tariffs having a larger impact. The effect was strongest in import-competing industries and industries not subject to excessive domestic regulation. While we find no evidence of a differential impact according to state-level characteristics, we observe complementarities between trade liberalization and additional industrial policy reforms.