Xu Xiaodong

Group Cell Architecture for Future Mobile Communication System

This paper describes some new contributions to the Generalized Distributed Antenna Architecture-Group Cell for future mobile communication system. The system architecture is described which allows the integration of multiple antenna techniques, e.g., MIMO, by spaced MIMO, distributed MIMO and virtual MIMO structure. The Slide Handover strategy based on the Group Cell architecture is also introduced with the Minimum Dwelling Time (MDT) based channel reserved prioritization algorithm in details. The capacity of Group Cell architecture and the performance of MDT algorithm based Slide Handover are analyzed. System level simulation results are given to show the performance increment of Group Cell architecture and Slide Handover strategy respectively.

Optimal energy efficiency capacity under joint design of sensing and transmission duration for cognitive radio system

Abstract Due to its opportunistic spectrum sharing capability, cognitive radio (CR) has been proposed as a fundamental solution to alleviate the contradiction between spectrum scarcity and inefficient utilization of licensed spectrum. In CR system (CRS), to efficiently utilize the spectrum resource, one important issue is to allocate the sensing and transmission duration reasonably. In this paper, the evaluation metric of energy efficiency, which represented the total number of bits that were delivered with per joule of energy consumed, is adopted to evaluate the proposed scheme. We study a joint design of energy efficient sensing and transmission durations to maximize energy efficiency capacity (EEC) of CRS. The tradeoff between EEC and sensing and transmission durations are formulized as an optimization problem under constraints on target detection probability of secondary users (SUs) and toleration interference threshold of primary users (PUs). To obtain the optimal solution, optimizing sensing duration and transmission duration will be first performed separately. Then, a joint optimization iterative algorithm is proposed to search the optimal pair of sensing and transmission durations. Analytical and simulation results show that there exists a unique duration pair where the EEC is maximized, and that the EEC of the proposed joint optimization algorithm outperforms that of existed algorithms. Furthermore, the simulation results also reveal that the performance of the proposed low complexity iterative algorithm is comparable with that of the exhaustive search scheme.

Capacity Analysis of Multi-user Diversity in Generalized Distributed Cellular Architecture

This paper analyzes the performance of utilizing multi-user diversity (MUD) strategy in generalized distributed cellular architecture-group cell. The group cell architecture can take full advantage of multi-antenna technologies and solve the problem of frequent handover caused by increase of carrier frequency. The system capacity of group cell is analyzed and the capacity gain brought by MUD in group cell is emphasized in this paper. The theoretical analyses are provided to give the capacity gain bought by MUD and the bottom bound of capacity gain is deduced. Simulation results are also presented to verify the theoretical analyses

Science and ICT in China

The session that is reported in this chapter was organized by Zhiyong Liu for the the National Natural Science Foundation of China (NSFC). The purpose of the session was to provide a forum for researchers, practitioners, and administrators in IT to exchange their information and ideas for research and development on IT. Four Chinese scientists gave presentations on the session. International colleagues participated this session. The following four abstracts included in this document introduce basic information for IT research (especially basic research) in China. In accordance with the purpose of the session, and due to the number of presentations that could be accepted in the session, the abstracts can only gave an outline of a small part of research (especially on communications and networking) on IT conducted in China. Still, from the abstracts readers can find valuable information for basic research on IT in China, as well as the policies of the states, various particular activities and research results.