Performance Comparison of Power Control Methods That Use Neural Network and Fuzzy Inference System in CDMA (original) (raw)

Power control in CDMA networks based on soft computing methods

Soft Computing, 2005

Power control is a fundamental procedure for CDMA mobile radio communication systems. In multiservice CDMA systems, power control should be used to minimise the transmission power of each connection, in order to limit the multiple access interference, while obtaining the desirable SIR levels. This paper starts from a transmitted-power allocation algorithm (TPAA) that considers a set of uplink transmissions, which should be supported by the system. In the sequel, the TPAA algorithm is used for training an Elman neural network, which, due to its internal characteristics, is applicable in the time critical context of power control. Simulations and numerical results are analysed for obtaining a solid basis for employing our scheme in the power control of CDMA systems.

Adaptive Sir Based Power Control for Cdma System Using Fuzzy Genetic Algorithm

2005

Towards wireless communication, efficient spectrum or radio resource management is of paramount importance due to ever increasing demands for communication services. The key allocation decisions of radio resource managements are connected with channel assignment and the transmitted powers. In DS-CDMA systems spectrum utility is not a problem. With tight power control algorithm, the system capacity in DS-CDMA systems can be enhanced. In this paper an adaptive Signal-to-Interference Ratio (SIR) feedback power control technique is described using fuzzy genetic algorithm. The SIR threshold control level of each mobile station is individually adjusted with reference to its own radio link condition. This new technique resulted in lower probability of unsuccessful transmission, less outage probability, and enhanced traffic capacity by maintaining the reliable quality of service (QoS) of the system. The proposed system is more stable when compared to the conventional systems.

Fuzzy Modeling of Uplink Transmit Power Control in a CDMA Network

2008

From its beginning, transmit power has always placed a significant constraint on the performance of wireless radio systems. The transmit power control problem can be characterized as that of maintaining adequate power in each transmitted waveform so as to increase the expectation that the minimum required SIR at the receiver will at least be reached. This has been shown not to be a trivial endeavor due to the variability of the physical channel with time as well as interference and other practical constraints on “infinitely” increasing transmit power. Several power control algorithms have been proposed, of which the class of distributed and autonomous transmit power control algorithms have been shown in literature to perform quite satisfactorily when compared to centralized schemes due to the moderate complexity that is achievable; and the vast control and signaling overhead that is saved. This thesis work explores the application of fuzzy control to the subject of modeling uplink t...

A New Power Control Algorithm for Cellular CDMA Systems

2009

The conventional closed-loop power control in cellular code division multiple access systems can only achieve limited performance due to its inability to track channel variations quickly. In this paper, we present a new power control algorithm which is able to increase the speed of convergence to track the changes in radio channel efficiently. Simulation results show that it outperforms the conventional algorithms.

Performance Analysis of Downlink Power Control in CDMA Systems

IEEE Sarnoff Symposium, Princeton, 2003

Three downlink power control algorithms have been studied and evaluated in this work. Additionally, an uplink power control algorithm has been modified and adapted for downlink. An enhancement has been proposed to one of the studied algorithms based on the ...

researchpaper Modified Variable Step Size Power Control Algorithm for CDMA Systems

Power control mechanism is an important issue for Code Division Multiple Access (CDMA) systems which helps in achieving higher capacity, combating against near far effect and provides high link performance. Unless a suitable power control mechanism is developed cellular systems cannot perform better. Power control allows to minimize the transmit power while keeping the system performance above the required value. In previous research [4], variable step size for closed loop power control system has been studied and results showed an increase in convergence speed and stability by properly choosing the step size. The new algorithm presented in this paper shows that it can perform better than variable step size power control algorithm and can obtain higher stability and convergence speed for step size δ at 0.1.

Optimization of power control parameters for DS-CDMA cellular systems

IEEE Transactions on Communications, 2001

This paper envisages a cellular system based on code-division multiple access and investigates the performance of a strength-based closed-loop power control (CLPC) scheme on the basis of different parameters, such as the number of bits of the power command, the quantization step size, and the user speed. On the basis of a log-linear CLPC model, an analytical approach has been developed that has allowed to determine the optimum quantization step size to be used for each value of the number of power command bits. Simulation results have permitted to support the analytical framework developed in this paper.

Improved Predictive Power Control Algorithms to Increase CDMA System Capacity

ITB Journal of Engineering Science, 2009

In this paper capacity of CDMA system is evaluated using an improved algorithm of channel prediction-based power control in Rayleigh fading channel environments. One of the most serious problems which degrades the performance of power control algorithm is the effect of feedback delay. To overcome the effect of feedback delay, power control algorithm relies on channel prediction techniques, which utilize the correlation property of the past channel measurements. In CDMA power control, however, the correlation property of channel measurements is destroyed because the transmit power is continuously updated for each power control interval. In order to restore the correlation property of the channel, the past channel measurements are compensated for by the same factors that were given by power updating for each power control interval. The prediction algorithm in this paper is proposed using the least mean square (LMS) technique. The result shows that the capacity of CDMA systems increase significantly when the improved predictive algorithm is used. Numerical evaluation shows that CDMA capacity increases by more than 40 % for fixed step algorithm and more than 50 % for variable step algorithm when the proposed algorithm is employed.

Machine learning based CDMA power control

2003

This paper presents binary and multiclass machine learning techniques for CDMA power control. The power control commands are based on estimates of the signal and noise s u b space eigenvalues and the signal subspace dimension. Results of ha0 different sets of machine learning algorithms are presented. Binary machine learning algorithms generate fixed-step power control (FSPC) commands based on estimated eigenvalues and SIRS. A fixed-set of power control commands are generated with multiclass machine learning algorithms. The results show the limitations of a fixed-set power control system, but aho show that a Bred-set system achieves comparable performance to high complexity closed-loop power control systems.