Papers by Keyword: MIMO

Abstract: The present work represents polarization reconfigurable MIMO antenna which is design to work at 2.4 GHz (WLAN) and C band application. An inverted U-shaped slot and two PIN diodes per radiator are incorporated in the circular patch antenna to achieve polarization reconfigurability between Linear and Circular polarization (RHCP or LHCP). A simple rectangular strip is utilized between the radiators to achieve isolation improvement from -14 dB to -22dB in the proposed design. Computer Simulation Technology (CST) 2018 is used to design and validate the polarization reconfigurable MIMO antenna with sufficient isolation. Surface current distribution, Envelope Correlation Coefficient (ECC) and Diversity Gain (DG) and axial ratio are calculated using simulation software and used to validate circularly polarized MIMO design’s diverse behavior. The design is fabricated in low-cost FR-4 material and measurement is done to verify the simulation results. The measurement results show close agreement with simulated results and proves that the proposed design can be a better candidate for WLAN and C band application with polarization reconfiguration properties.

Abstract: This paper presents a Backstepping controller for five degrees of freedom Spherical Inverted Pendulum. Since the system is nonlinear, unstable, underactuated and MIMO and has a nonsquare form, the classic control design cannot be applied to control it. In order to remedy this problem, we propose in this paper a new method based on hierarchical steps of the Backstepping controller taking into a count the nonlinearities that cannot be neglected. Furthermore, a Linear Quadratic Regulator controller and LQR + PID based on the linearized system model are also designed for performance comparison. Finally, a simulation study is carried out to prove the effectiveness of proposed control scheme and is validated using the virtual reality environment that proves the performance of the Backstepping controller over the linear ones where it brings the pendulum from any initial condition in the upper hemisphere while the base is brought to the origin of the coordinates.

Abstract: The combined system STBC-OFDM has considered an important association to integrate into actual and next wireless system. Such as the Wifi standard, WiMAX standard, the LTE fourth generation of mobile. Which combat the effect of multipath fading channel that limited the performance in wireless communications. In recent years, this association has been a large study to achieve a better performance of BER and designed for the different situation of the wireless channel from slow to fast fading channel, with various parameters of OFDM modulation and under different condition of STBC code. To contribute in this axis of research, we present a comparative study of the simulation result for STBC-OFDM. The first results are the comparison between three schemes of STBC (Alamouti code, Orthogonal STBC, Non-Orthogonal STBC) associated with OFDM. The second results are the comparison between three schemes when applied OFDM in different parameters and also when these codes used without OFDM modulation. The channel considered across simulation is Rayleigh fading channel that presented a real situation of the wireless environment, the Maximum Likelihood (ML) is used for detection the data that encoded in the first. The performance of three schemes is evaluated by BER (Bit Error Rate) versus the different values of SNR (Signal Noise Ratio).

Abstract: Wireless signal reflecting, scattering or refracting causes the generation of multipath effects. Multipath causes multiple copies of the same wireless signal, These copies to different path to reach the receiver. The signal generated by a copy of the same produce serious interference. MIMO (Multiple-Input Multiple-Output) technology can make the interference caused by the multipath significantly reduced. In this paper, in the context of indoor and outdoor, through TP-LINK-WR845N (MIMO 2*2, which have 2 launching antennas and 2 receiving antennas) to verify the superior performance of this technology under indoor condition, at the same time we discover that the MIMO technology does not increase the coverage under outdoor condition, because there is only the power gain, no diversity gain.

Abstract: To introduce extra coding gain to Multi-input Multi-output (MIMO) system, how to combine MIMO and convolutional code (CC) was studied in two cases. In the first case, the type of MIMO was limited to pure spatial multiplexing. Then in the second case, the type was extended to the hybrid of spatial multiplexing and transmission diversity. Several encoding-decoding schemes were designed. For each scheme, its advantage and disadvantage were analyzed, and bit error rate performance was evaluated by simulation. Finally the scheme with best performance and acceptable complexity was elected from candidates for each case.

Abstract: The paper mainly analyzed the robot kinematics of the line heating plate. In order to realize the moving of complex trajectory for the robot, a forward kinematics modeling and the simulation of inverse kinematics are carried out. Firstly, with the D-H modeling method, the line heating plate robot forward kinematics equations and the spatial geometric model of the manipulator are set up, then multi-input multi-output systems based on support vector machines algorithm is used to establish the inverse kinematics model for the robot . At last, the simulations of tracing complex trajectory with the inverse kinematics model are carried out, and the results show that the model derived by SVM can trace the trajectory very well.

Abstract: This paper investigated the problem of transmit power minimization to meet the users’ outage probability constraints in downlink smart antennas-MIMO (SA-MIMO) systems. Firstly, a downlink multi-user SA-MIMO system model is established, and the transmit power optimization problem is formulated. The optimization problem jointly optimizes the beam-forming vectors and user outage probability. Then, the outage-based optimization problem is transformed into a geometric programming problem in which the beam forming vectors were obtained by maximum diagonal element (MDE) rule. Some numerical results show that the proposed method in this paper is viable and the transmit power in downlink SA-MIMO systems significantly descreases relative to traditional MIMO systems.

Abstract: Applying Multiple-Input Multiple-Output (MIMO) technology in terrestrial wireless networks can obtain large capacity gain. Therefore, MIMO technology is widely applied in satellite communication system, in which orbital positions are increasingly crowded and frequency resources are of shortage. This paper attempts to research on channel capacity in 2×2 dual-polarized MIMO mobile satellite (DMMS) system and discovers that when XPD (Cross Polarization Discrimination) is above zero, the channel capacity increases approximately linearly with the XPD within certain range. Adding Ricean factor K in consideration of its special features, the system’s capacity increases with the Ricean factor K. Simulation results demonstrate that the application of MIMO technology in satellite mobile communication system can improve the channel capacity significantly, providing great support for the development of future satellite MIMO technology.

Abstract: To enhance the ber performance of pseudo physical-layer network coding (ppnc) scheme, a new scheme called pseudo physical-layer soft network coding (ppsnc) scheme is proposed, ppsnc adopts soft information not hard decision information, and its ber performance is better than ppnc. Meanwhile ppsnc has no synchronization problem compared with physical-layer network coding (pnc) scheme. At the same time, we also discuss the performance of ppsnc in mimo environment. The simulation results show that mimo-ppsnc outperforms the other schemes.

Abstract: In order to get better trade-off between detection performance and calculating complexity, an improved detection algorithm was presented here. QRD-M algorithm is performed for several layers firstly, and successive interference cancellation detection algorithm was used to detect the bottom several layers parallel, and the candidate sequence with smaller PAM was selected out as the answer. Simulation results show the validity of proposed algorithm.