• Characterization of the numerical Group velocity in Yee's FDTD Grid

      Valcarce, Alvaro; Song, Hui; Zhang, Jie; University of Bedfordshire (IEEE, 2010-12)
      A method is introduced for the optimization of the numerical group velocity in standard finite-difference time-domain (FDTD) electromagnetic simulations. Through this method analytical expressions for the extrema of are presented for the first time, thus also characterizing its anisotropy. The knowledge of these expressions is hence essential for the evaluation of the anisotropy error in FDTD-based electrodynamics simulations of the propagation of wavepackets in 2D and 3D. This can be of assistance, for example, in the design of error-bounded FDTD simulations with pulsed sources at low computational cost.
    • General results on SNR statistics involving EESM-based frequency selective feedbacks

      Song, Hui; Kwan, Raymond; Zhang, Jie; University of Bedfordshire (IEEE, 2010-05)
      Novel methods of obtaining the moment generating function (MGF) and moments of the exponential effective SNR mapping (EESM) signal-to-noise ratio (SNR) over N jointly distributed fading channels are presented. Based on these methods, novel explicit expressions of the MGF and moments over arbitrary number of correlated Nakagami-m fading channels are proposed. Numerical evaluation of these expressions shows that the proposed approach can be a useful and efficient analytical tool in characterizing the statistics of EESM over correlated Nakagami-m fading channels.
    • A hybrid swarm intelligence algorithm for multiuser scheduling in HSDPA

      Aydin, Mehmet Emin; Kwan, Raymond; Leung, Cyril; Maple, Carsten; Zhang, Jie; University of Bedfordshire (Elsevier, 2012-05-17)
      Multiuser scheduling is an important aspect in the performance optimization of a wireless network since it allows multiple users to access a shared channel efficiently by exploiting multiuser diversity. To perform efficient scheduling, channel state information (CSI) for users is required, and is obtained via their respective feedback channels. In this paper, a more realistic imperfect CSI feedback, in the form of a finite set of Channel Quality Indicator (CQI) values, is assumed as specified in the HSDPA standard. A mathematical model of the problem is developed for use in the optimization process. A hybrid heuristic approach based on particle swarm optimization and simulated annealing is used to solve the problem. Simulation results indicate that the hybrid approach outperforms individual implementations of both simulated annealing and particle swarm optimisation.
    • A mathematical programming approach to solve the mobile WiMax base station location problem

      Mohammed, A.; Huang, Wei; Zhang, Jie (Pacilantic International, 2010)