Comparison of Measurement and Prediction of ITU-R Recommendation P.1546

This paper compares measurement with prediction of ITU-R Recommendation P.1546. This recommendation mainly depends on propagation curves which are based on the measurement result. The basic field strength is derived from the curve corresponding to transmitting antenna height, frequency and required distance and then correction factor is added to this. There are two important correction values in this recommendation. First factor is the correction for receiving/mobile antenna height and second factor is the terrain clearance angle (TCA) correction. This paper specially focuses on first correction factor with regard to R which is representative of the height of the ground cover surrounding receiving/mobile antenna. We propose several considerations to enhance the prediction accuracy of ITU-R Recommendation P.1546

Performance of Channel Prediction Using 3D Ray-tracing Scheme Compared to Conventional 2D Scheme

Channel prediction tools using ray-tracing scheme can be used to get information of communication channel instead of channel measurement. Three dimensional (3D) ray-tracing technique is known for the better accuracy compared to two dimensional (2D) ray-tracing. But it requires a lot of calculations, thus 2D simulation has been generally performed. This paper shows how precious 3D ray-tracing predicts the received power indoors compared to 2D one. For this work, wave propagation phenomena are analyzed using Finite Difference Time Domain (FDTD) method and the channel measurement data also will be offered as a standard of comparison

Efficient Cell Planning Method by Considering Initial Conditions

This paper focuses on cell planning method and optimal Access Point (AP) location. Cell planning can reduce the adjacent channel interference and minimize the number of AP. So an efficient cell planning method can save cost and time of systems setup. We introduce some methods, compare one another and suggest an efficient method. Existing method is considering a variety of objective functions. So their complexity makes it difficult to design wireless systems. The new method which will be suggested in this paper considering a special condition reduces a lot of calculation quantity

Coordinated Beamforming with Limited BS Cooperation for Multicell Multiuser MIMO Broadcast Channel

The capacity of downlink multi-input multi-output (MIMO) systems is significantly limited by inter-cell co-channel interference (CCI). Improving the erformance of cell edge users who suffers strong inter-cell CCI is still a crucial issue. In this paper, coordinated beamforming (CBF)lgorithm for multicell multiuser MIMO system is proposed to cope with the presence of intel-cell CCI. In multicell environment with MIMO channel, limited base station (BS) cooperation is considered to design optimal transmit and receive beamformers which make interference-free at the receiver. Simulation results show that the proposed algorithms can improve the capacity of cell edge user effectively as well as the overall system capacity for multiuser multicell MIMO system

Isolation and Characterization of a Defensin-Like Peptide (Coprisin) from the Dung Beetle, Copris tripartitus

The antibacterial activity of immune-related peptides, identified by a differential gene expression analysis, was investigated to suggest novel antibacterial peptides. A cDNA encoding a defensin-like peptide, Coprisin, was isolated from bacteria-immunized dung beetle, Copris tripartitus, by using differential dot blot hybridization. Northern blot analysis showed that Coprisin mRNA was up-regulated from 4 hours after bacteria injection and its expression level was reached a peak at 16 hours. The deduced amino acid sequence of Coprisin was composed of 80 amino acids with a predicted molecular weight of 8.6 kDa and a pI of 8.7. The amino acid sequence of mature Coprisin was found to be 79.1% and 67.4% identical to those of defensin-like peptides of Anomala cuprea and Allomyrina dichotoma, respectively. We also investigated active sequences of Coprisin by using amino acid modification. The result showed that the 9-mer peptide, LLCIALRKK-NH2, exhibited potent antibacterial activities against Escherichia coli and Staphylococcus aureus

Superresolution TOA Estimation With Computational Load Reduction

Although the superresolution multipath delay profile (MDP) estimation technique enhances the time resolution of a low-resolution MDP by using matrix computations, the computational load for the matrix computations is a problem, because it drastically increases with the length of the MDP. Because positioning systems require the time of arrival (TOA) of the first path only, it is possible to reduce the computational load by applying the matrix computations only to the part of the MDP that is narrowed but still includes the TOA of the first path. This paper proposes a scheme for determining the observation window of MDP from the low-resolution TOA estimates, which are obtained from the MDPs produced by the pseudonoise correlation method. The proposed scheme makes use of the random nature of the low-resolution TOA estimates to further reduce the observation window. The computational efficiency and estimation accuracy of the proposed scheme are examined by channel simulations based on the Saleh–Valenzuela indoor channel model and are also compared with the computational efficiency and estimation accuracy of the conventional superresolution technique without the observation window reduction

Femtocell/Macrocell Interference Analysis for Mobile WiMAX System

Femtocell can provide better indoor coverage and capacity of cellular systems. In order to operate femtocell appropriately, RF interference analysis between femtocells and macrocells is needed. In this paper, we discussed the impact of interference by the introduction of femtocell in Mobile WiMAX system. Performance degradation was evaluated for the downlink case by system level simulation. Simulation results shows that the impact of interference from macrocell to femtocell is more severe than from femtocell to macrocell. By allocating different frequency bands for femtocell and macrocell, performance degradation can be negligible.This work was partly supported by the Brain Korea 21 project and the IT R&D program of MKE/IITA. [2007-S-029-02, Development of Indoor WiBro System for Home and Enterprise