Jamming Resistant Receivers for Massive MIMO

We design jamming resistant receivers to enhance the robustness of a massive MIMO uplink channel against jamming. In the pilot phase, we estimate not only the desired channel, but also the jamming channel by exploiting purposely unused pilot sequences. The jamming channel estimate is used to construct the linear receive filter to reduce impact that jamming has on the achievable rates. The performance of the proposed scheme is analytically and numerically evaluated. These results show that the proposed scheme greatly improves the rates, as compared to conventional receivers. Moreover, the proposed schemes still work well with stronger jamming power.Comment: Accepted in the 42nd IEEE Int. Conf. Acoust., Speech, and Signal Process. (ICASSP2017

Supervised Hashing with End-to-End Binary Deep Neural Network

Image hashing is a popular technique applied to large scale content-based visual retrieval due to its compact and efficient binary codes. Our work proposes a new end-to-end deep network architecture for supervised hashing which directly learns binary codes from input images and maintains good properties over binary codes such as similarity preservation, independence, and balancing. Furthermore, we also propose a new learning scheme that can cope with the binary constrained loss function. The proposed algorithm not only is scalable for learning over large-scale datasets but also outperforms state-of-the-art supervised hashing methods, which are illustrated throughout extensive experiments from various image retrieval benchmarks.Comment: Accepted to IEEE ICIP 201

Essays on Corporate Finance

This thesis is comprised of three chapters. In the first chapter, I exploit the 2012 French introduction of a financial transaction tax (FTT) levied on stock purchases to examine its impact on corporate investment. Investment may decrease due to the increased cost of capital. The FTT, however, may encourage investment by reducing short-termism. I find an overall positive effect of the FTT on corporate investments. I also find that the FTT causes a shift from short-term to long-term ownership, an improvement in investment sensitivity to changes in growth opportunities, and an increase in likelihood and quality of acquisitions. These results are in line with the prediction that the FTT encourages investment by inducing long-term ownership and alleviating short-termism. In the second chapter, coauthored with Beatriz Garc´ıa Osma, Anna Toldr`a-Simats and Fengzhi Zhu (UC3M), we examine whether voting requirements in M&As induce disclosure, lowering information asymmetry. We find that acquirers subject to share-holder voting provide more 8-K disclosure during the transaction period, and are more likely to provide timely disclosure of the merger agreement, information on expected synergies and post-merger earnings forecasts. For acquirers subject to voting, we docu-ment a more negative association between disclosure and bid-ask spread than in other acquirers, and a more positive association between disclosure and transient institutional sales. Lower bid-ask spread and higher transient institutional sales are associated with higher voting support and likelihood of deal completion. These results suggest that the induced disclosure is informative and it can affect voting outcomes through changing the deal valuation and the shareholder base. Evidence from falsification tests and a regression-discontinuity design supports the causal interpretation of the positive effect of shareholder voting on disclosure. In the third chapter, a joint work with Faiza Majid (UNSW), we examine the effect of tariff changes on the market for corporate assets. On the one hand, the intensified competition from foreign entry due to tariff reductions can induce firms to divest its less productive assets. On the other hand, tariff reductions can alter foreign firms’ entry mode to export instead of acquiring assets and producing locally. Using detailed information about corporate asset sales, we find that tariff changes can affect both supply and demand sides of the market for corporate assets. Our study highlights that the lower demand can limit some firms’ ability to divest assets to become more efficient. Some firms, however, are able to divest assets that are less important and less affected by the lower demand to cope with increased competition.Programa de Doctorado en Empresa y Finanzas / Business and Finance por la Universidad Carlos III de MadridPresidente: Miguel Duro Rivas.- Secretaria: María Gutiérrez Urtiaga.- Vocal: Alberta Di Giul

Adoption of supply chain analytics in SMEs: an exploratory study

Objective Given the extant knowledge in the literature of the intersection among big data, analytics, and supply chain management, this thesis is aimed to explore the adoption of supply chain analytics in the SMEs. More specifically, the thesis’ main objectives are to investigate under what situations the SMEs adopt supply chain analytics and provide the recommendations for SMEs in adopting supply chain analytics. Summary Based on the content analysis of interviews with solution providers from different countries, the thesis has explored the main motivations behind the adoptions from SMEs, and the necessary existing resources and the challenges for SMEs to adopt supply chain analytics. Given such findings, a framework for future research on the factors that affect the adoption of supply chain analytics in SMEs is proposed and detailed recommendations for such companies are also discussed. Conclusions In conclusion, the adoption of supply chain analytics in SMEs is still in modest rate due to certain barriers and complex required resources for SMEs in adopting such practices. The decisions to adopt supply chain analytics in SMEs depends on factors such as perceived benefits, dynamic environment, data-driven culture, necessary resources, and challenges of the adoptions. The thesis recommends that SMEs should firstly build basic awareness of analytics, and technical capability related to data management before adopting supply chain analytics. Then, SMEs also need to emphasize on change management and adopt alignment strategy to optimize the benefits gained from analytics adoptions