Challenges and Trade-offs in Real-Time Implementation of DSP for Coherent Transmission

We review different real-time implementation platforms for digital signal processing. We discuss circuit implementation of coherent receivers and design trade-offs involving circuit complexity, throughput and power dissipation

Digital monitoring and compensation of MDL based on higher-order Poincaré spheres

We present a digital technique able to monitor and compensate for the mode-dependent losses (MDL) in space-division multiplexing (SDM) transmission systems. The working principle of the technique is based on the analysis of the received signal samples in the higher-order Poincaré spheres (HoPs). When an arbitrary pair of tributaries is represented in the respective HoPs, the effect of the MDL can be modeled as a simple shift of the constellation points in a such sphere. Therefore, the MDL can be estimated by computing those shifts over all the HoPs and the induced signal distortions can be compensated by re-centering all the constellations in the respective HoPs. It should be highlighted that the proposed technique is scalable with an arbitrary number of spatial channels, modulation format agonistic and free of training sequences. The HoPs-based MDL monitoring (compensation) technique allows the MDL estimation (compensation) up to values of ≈ 6 dB. The proposed technique can partially compensate the MDL distortion, making a MDL sensitive algorithm in an insensitive one. When the proposed technique assists a HoPs-based space-demultiplexing algorithm, it provides signal-to-noise ratio (SNR) enhancements of 2, 4 and 8 dB for PM-QPSK, PM-16QAM and PM-64QAM signals, respectively, for the particular case of a SDM-based transmission system with a spatial diversity of 2 and 2 dB of MDL.publishe

Effects of Labour Regulation on Manufacturing Firms in India: A Leximetric Approach

Abstract Inefficiencies and rigidities in the supply of inputs caused by strict laws and regulation could lead to distortions in the production structures of firms. These distortions, when magnified, can have adverse effects on the economic performance of a country. The study by Botero et al. (Botero, Juan C., Simeon Djankov, Rafael La Porta, Florencio Lopez de-Silanes, and Andrei Shleifer. 2004. “The Regulation of Labor.” The Quarterly Journal of Economics 119: 1339–1382.) among others, has observed that richer counties with social welfare supports tend to regulate labour less than relatively poorer countries; but, these studies concentrate mainly on country-wide or cross-country data leaving out variations exclusively found in micro-level data. This study fills a gap in the literature by conducting a comprehensive study of the effects of labour laws on output and productivity of manufacturing firms in Indian states. Unlike previous studies which measure the strength of labour regulation by interpreting labour laws, this study measures the same by mining information from case-law citations of labour laws and builds an index of labour litigiousness which proxies for the strength of labour regulation. Results show that labour litigation and industrial disputes have significant negative influences on both output and productivity of manufacturing firms.</jats:p

Shocking resilience? Effects of extreme events on constitutional compliance

It is often argued that governments take advantage of extreme events to expand their power to the detriment of the political opposition and citizens at large. Violations of constitutional constraints are a clear indication of such opportunistic behaviour. We study whether natural disasters, conflicts and other extreme events systematically diminish governments' compliance with constitutional constraints. Our results indicate that governments are most likely to overstep their competences or disregard their responsibilities during civil conflicts, at the onset of international sanctions or following successful coups d’état. Interestingly, Cold War interventions by the United States that installed or supported a political leader led to a decrease in constitutional compliance in the target country, whereas Soviet interventions had no such effect. In contrast, banking crises and natural disasters, which threaten societies at large, but not necessarily the political elite, do not cause a significant decline in constitutional compliance