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Outage Analysis and Power Allocation for Space-time Block Coded Two-way Relaying

100%

Yıldız M. , Aygölü Ü.

tom Vol. 3, no. 5

25--31

In this paper, we consider the two-way relay channel (TWRC) over which communication is performed using spacetime block codes (STBC) with physical-layer network coding (PNC) protocol. The three-node two-way relaying (TWR) model consists of two end nodes (sources) simultaneously communicating with each other over a relay node where each node is equipped with two antennas and uses Alamouti’s STBC to provide diversity. We consider non-reciprocal channels where fading channel coefficients are independent for opposite directions of the same link. We first derive closed form expressions for the outage probability of the STBC-TWR system and uncoded TWRC assuming equal transmit power at each node and decode-and-forward (DF) strategy at the relay. We show that the STBC-TWR system significantly improves the uncoded TWRC outage performance. Then, to further improve the performance, we propose an optimal ower allocation in TWR scheme employing Alamouti’s STBC and PNC protocol. The optimal power allocation is obtained by maximizing the sum-rate under the total power constraint. We show that the optimal power allocation considerably improves the outage performance as well as the sum-rate compared to the equal-power case.

Windup prevention for MIMO systems in the frequency domain

100%

Hippe P. , Deutscher J.

tom Vol. 19, no. 4

355-369

Input saturation can have an undesired influence on the transients of the closed loop system and it can even lead to an unstable behavior. Controller windup is caused by badly damped or unstable modes in the compensator and controller windup is due to fast dynamics of the closed loop system. In a two-step approach one can first prevent controller windup by the so-called observer technique and if, in addition, there exists the danger of plant windup one adds an additional dynamic element to prevent it. There also exists a one-step approach that prevents controller and plant windup at the same time. This paper shows how both approaches to windup prevention can be designed directly in the frequency domain without recourse to time domain arguments. A simple example demonstrates the windup effects and their prevention.

Multivariable Adaptive Controller for the Nonlinear MIMO Model of a Container Ship

63%

Brasel M. , Dworak P.

tom Vol. 8, no. 1

41--47

The paper presents an adaptive multivariable control system for a Multi-Input, Multi-Output (MIMO) nonlinear dynamic process. The problems under study are exemplified by a synthesis of a course angle and forward speed control system for the nonlinear four-Degrees-of-Freedom (4-DoF) mathematical model of a single-screw, high-speed container ship. The paper presents the complexity of the assumed model to be analyzed and a synthesis method for the multivariable adaptive modal controller. Due to a strongly nonlinear nature of the ship movements equations a multivariable adaptive controller is tuned in relation to changeable hydrodynamic operating conditions of the ship. In accordance with the given operating conditions controller parameters are chosen on the basis of four measured auxiliary signals. The system synthesis is carried out by linearization of the nonlinear model of the ship at its nominal operating points in the steady-state and by means of a pole placement control method. The final part of the paper includes results of simulation tests of the proposed control system carried out in the MATLAB/Simulink environment along with conclusions and final remarks.

Design and FPGA implementation of module for space multiplexing in multi-user MIMO system

63%

Dabetić R. , Saranovac L.

tom R. 89, nr 8

162--165

MIMO (multiple in multiple out) antenna system draw attention in the recent years due to its potential for achieving high data rates. In this work novel DSP algorithm and FPGA implementation will be presented that allows transmitting M data streams to M receiving antennas from N transmitting antennas (M ≤ N) into the same frequency with total interference suppression while maximizing channel gain for each data stream at the same time.

W artykule zaprezentowano nowy algorytm DSP z implementacja w FPGA umożliwiający transmisję strumienia M danych do M anteny odbiornika z anteny przesyłowej N (M ≤ N) z tą sama częstotliwością z tłumieniem zakłóceń – przy maksymalizacji wzmocnienia dla każdego strumienia danych w kanale.