In this paper, we present a simple method to approximate the bivariate Suzuki distribution by a bivariate Lognormal distribution. In particular, each Suzuki random variable (RV) is approximated by a new Lognormal RV, and the correlation coefficient between two Suzuki RVs is approximated by a new correlation coefficient between two Lognormal RVs. Numerical results validate the accuracy of this approximating method, and this method will facilitate the future analysis and calculation of the diversity system over correlated Suzuki channels.
To evaluate the distribution of common mode noise current generated by an LED lamp flowing on the lighting duct rail, radiation noise on the lighting duct rail is investigated by measuring the magnetic field distribution which correlates well with the common mode noise current distribution. The trough of the magnetic field distribution is observed around the position where the LED lamp is installed. When the duct rail is longer than the wavelength, the peaks and troughs of the magnetic field distribution on the duct rail appear every half wavelength. To examine the measurement result, a single wire model is proposed to simulate the distribution of the LED noise on the lighting duct rail and its result is compared with the measurement result. A good agreement between these results is obtained. This single wire model is successfully expressed both the duct rail part and the noise source part.
In cognitive radio networks which utilize unused spatial dimensions for secondary transmissions, estimating the number of streams provides essential information for the maximization of secondary throughput. By estimating the number of streams transmitted by the primary users, the secondary network can determine the number of spatial degrees of freedom that are available for opportunistic spectrum use. In this paper, we study the problem of streams number estimation in the context of cooperative cognitive radio network. We employ the well-known minimum description length (MDL) algorithm at secondary terminals and propose a decision fusion method which exploits the estimation bias of the MDL algorithm. The proposed method can provide improved estimation performance especially in the low signal-to-noise ratio region.
This paper is concerned with an analysis of scattered waves from an aircraft by using the Ray-Tracing Method (RTM) based on the imaging method. In order to reduce computation time, we propose a simple algorithm for rapid ray searching. In this paper, we describe a concept of a proposed method and show a numerical simulation of scattered powers in a large analytical region. Moreover, as one example, we show a measurement result of scattered powers which was performed in the Tokyo Bay area. Comparing the numerical result with the experimental one, we investigate the accuracy of the proposed method.
This letter discusses a fiber design for lump Raman amplification (LRA) at 1270nm wavelength used in passive optical networks (PON) using hybrid-Raman amplifiers, which are previously proposed. For simplicity, refractive-index profile is assumed to be step-index. Gain and optical signal noise ratio (OSNR) are calculated as a function of Δ. Considering a fiber fuse, we discuss a design of fibers used for lump Raman amplification. To realize a compact LRA, we propose a use of hole-assisted fibers (HAF) when high power laser is available.
In PONs, an optical subscriber unit (OSU) is shared by users. Since the upload/download speed depends on the available bandwidth of the OSU, the utilization ratio of OSU bandwidth must be equally distributed to offer fair upload/download speeds. A dynamic load-balancing (DLB) method to distribute OSU’s traffic load equally in λ-tunable WDM/TDM-PONs has been realized by monitoring the buffer depth of each OSU. However, it is difficult to monitor the traffic load if the OSU has an unused capacity. This paper proposes a novel DLB method for λ-tunable WDM/TDM-PONs. The proposed method makes the traffic load of OSU uniform by monitoring the traffic volume itself, even if some available capacity is present. In addition, to quickly determine the optimal OSU-ONU assignments, a determination algorithm based on the proposed method is derived from Jain’s fairness index. The proposed method is validated by simulations based on a measured traffic model.