Improved Linearly Constrained Minimum Variance Algorithm for 5G Communications System

Beamforming is a process formulated to produce the radiated beam patterns of the antennas by completely building up the processed signals in the direction of the desired terminals and cancelling beams of interfering signals. Adaptive beamforming is a key technology of smart antenna. The core is to obtain optimum weights of the antenna array by some adaptive beamforming algorithms and finally adjust the main lobe to focus on the arriving direction of the desired signal as well as suppressing the interfering signal. There are several beamforming algorithms that includes Linearly Constrained Minimum Variance (LCMV) algorithm in which Self Nulling Issue is further reduced by adding multiplier to the MCMV algorithm and it is referred as Improved LCMV (IMPLCMV). A Comparative analysis is done for different multipliers and it is found that w=0.15 gives best result with minimum interference of flat response and also self-nulling issues can be reduced.

Observation and verification of the Fresnel and Arago interference laws using adaptive photodetectors

The Fresnel and Arago interference laws relate the polarization of the electromagnetic field to the interference phenomenon. Different methods and interferometers have been reported to verify these laws; most of them rely on visual inspection to determine the positions of maximum and minimum interference. In this report, the observation and verification of the Fresnel and Arago interference laws using adaptive photodetectors are presented. These photodetectors generate an electrical current proportional to the square of the visibility of the interference pattern; thus the gradual change from the appearance of the interference pattern (maximum visibility) to its disappearance (minimum or null visibility) is detected as an electrical current. The extreme values of the interference pattern visibility can be accurately assessed, in real time and without any signal processing using. A difference of 3 orders of magnitude between the signals measured in the positions of maximum and minimum interference is demonstrated. Due to the adaptive properties of the adaptive photodetectors (compensation of the irregularities of the interfering beams and suppression environmental fluctuations), the proposed method can be suitable for teaching purposes in undergraduate laboratories.

An Interference Suppression Method for Non-Contact Bioelectric Acquisition

For non-contact bioelectrical acquisition, a new interference suppression method, named ‘noise neutralization method’, is proposed in this paper. Compared with the traditional capacitive driven-right-leg method, the proposed method is characterized with that there is an optimal gain to achieve the minimum interference output whatever for the electrode interface impedance mismatch caused by body motion and is more effective for smaller reference electrode areas. The performance of traditional capacitive driven-right-leg method is analyzed and the difficulty to suppress interference in the case of the interface impedance mismatch is pointed out. Therefore, a noise neutralization method is proposed by applying the reference electrode and a 50 Hz band-pass filter to obtain the interference of the human body and adapting the gains to neutralize the interference inputs of two acquisition electrodes and achieve the minimum interference output. The performance of the proposed method is theoretically analyzed and verified by the experiment results, which shows that the proposed method has similar performance to that of the traditional capacitive driven-right-leg method with electrode interface impedance match, while has better interference suppression ability with electrode interface impedance mismatch caused by body motion. It is suggested that the proposed method can be preferred in the case of limited reference electrode area or interface impedance mismatch.

Proteção em Redes Ópticas Elásticas com Multiplexação Espacial

In this paper, we summarize the contributions of the Doctoral Thesis entitled Protection in Elastic Optical Networks with Spatial Multiplexing. This thesis proposes solutions for protection of elastic optical networks with spatial multiplexing, aiming at reducing the blocking of requests and the improvement of resource utilization. For this, we take into account the use of different schemes to paths protection, adaptive modulation, traffic grooming, spectrum overlap in protection paths, minimum interference routing and multipath routing. The algorithms proposed will allow the provisioning of protection in optical networks that will transport much greater volumes of traffic than do the current networks.

Three Local Search Meta-Heuristics for the Minimum Interference Frequency Assignment Problem (MI-FAP) in Cellular Networks

The minimum interference frequency assignment problem (MI-FAP) plays an important role in cellular networks. MI-FAP is the problem of finding an assignment of a small number of frequencies to a large number of transceivers (TRXs) that minimizes the interferences level. The MI-FAP is known to be NP-Hard, thus it cannot be solved in polynomial time. To remedy this, researchers usually use meta-heuristic techniques to find an approximate solution in reasonable time. Here, the authors propose three meta-heuristics for the MI-FAP: a variable neighborhood search (VNS) and a stochastic local search (SLS) that are combined to obtain a third and a new one, which is called VNS-SLS. The SLS method is incorporated into the VNS process as a subroutine in order to enhance the solution quality. All three proposed methods are evaluated on some well-known datasets to measure their performance. The empirical experiments show that the proposed method VNS-SLS succeeds in finding good results compared to both VNS and SLS confirming a good balance between intensification and diversification.