In recent years, the world economy has been shaped dramatically by the globalization of production and markets, as well as the growing importance of knowledge in economic activity, that is the rise of the knowledge-based economy. These trends are likely to continue and bring about challenges for developing countries. These countries seek to achieve a position in the world economy that allows them to benefit from world economic growth but at the same time avoid the negative aspects of economic dependency on foreign countries and companies. Simultaneously developing countries try to reduce the gap between their knowledge base and the knowledge base of industrialized countries. Technological upgrading is a precondition for a continuing shift towards higher value-added economic activities and, thus, the creation of wealth. Many examples from developing countries underline that the processes of world-market oriented growth, technological upgrading, and innovation are concentrated in large urban centers.The role of urban regions in a knowledge-based economy has attracted the attention of researchers in recent years. However, in the growing number of publications on this subject, the vast majority use data and examples from regions in industrialized countries and, despite growing interest in the matter, only a limited number of empirical studies have addressed the role of technologically advanced regions in developing countries.Within China, the Zhongguancun Science Park (ZGC) in Beijing is regarded as the leading technological and most innovative region. ZGC, located in the northwestern part of Beijing, has the highest concentration of top-level universities and public research institutions in China, and is host to more than 7000 high-tech companies, mainly in the fields of electronics and software but also in biotechnology and advanced manufacturing, among others (ZGC Administrative Committee, 2003). ZGC has attracted the interest of researchers dealing with technological upgrading as well as

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Abstract:Light beams can carry orbital angular momentum (OAM) associated to the helicity of their phasefronts. These OAM modes can be employed to encode information onto a laser beam for transmitting not only in a fiber link but also in a free-space optical (FSO) one. Regarding this latter scenario, FSO communications are considered as an alternative and promising mean complementing the traditional optical communications in many applications where the use of fiber cable is not justified. This next generation FSO communication systems have attracted much interest recently, and the inclusion of beams carrying OAM modes can be seen as an efficient solution to increase the capacity and the security in the link. In this paper, we discuss an experimental demonstration of a proposal for next generation FSO communication system where a light beam carrying different OAM modes and affected by M turbulence is coupled to the multimode fiber link. In addition, we report a better and more robust behavior of higher order OAM modes when the intermodal dispersion is dominant in the fiber after exceeding its maximum range of operation.

Abstract-This paper proposes a novel joint resource allocation algorithm combining dynamic user grouping, multi-cell cooperation and resource block (RB) allocation for single carrierfrequency division multiple access (SC-FDMA) uplink in multicell virtual MIMO systems. We first develop the dynamic multicell user grouping criteria using minimum mean square error (MMSE) equalization and adaptive modulation (AM) with bit error rate (BER) constraint. Then, we formulate and solve a new throughput maximization problem whose resource allocation includes cell selection, dynamic user grouping and RB pattern assignment. Furthermore, to reduce the computational complexity significantly, especially in the case of large numbers of users and RBs, we present an efficient iterative Hungarian algorithm based on user and resource partitions (IHA URP) to solve the problem by decomposing the large scale problem into a series of small scale sub-problems, which can obtain close-to-optimal solution with much lower complexity. The simulation results show that our proposed joint resource allocation algorithm with dynamic multicell user grouping scheme achieves better system throughput with BER guarantee than fixed user grouping algorithm and other proposed schemes in the literature.

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