Study of Power Control in CDMA System on the basis of optimization Technique: A Survey (original) (raw)
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IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences
In this paper, we propose an approach to solve the power control issue in a DS-CDMA cellular system using genetic algorithms (GAs). The transmitter power control developed in this paper has been proven to be efficient to control co-channel interference, to increase bandwidth utilization and to balance the comprehensive services that are sharing among all the mobiles with attaining a common signal-to-interference ratio(SIR). Most of the previous studies have assumed that the transmitter power level is controlled in a constant domain under the assumption of uniform distribution of users in the coverage area or in a continuous domain. In this paper, the optimal centralized power control (CPC) vector is characterized and its optimal solution for CPC is presented using GAs in a large-scale DS-CDMA cellular system under the realistic context that means random allocation of active users in the entire coverage area. Emphasis is put on the balance of services and convergence rate by using GAs.
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.
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.
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.
Optimal power control in CDMA mobile networks
Code Division Multiple Access (CDMA) is interference limited multiple access system. Because all users transmit on the same frequency, internal interference generated by the system is the most significant factor in determining system capacity and call quality. The transmit power for each user must be reduced to limit interference, however, the power should be enough to maintain the required signal energy per bit to noise power spectral density ratio (Eb/No) for a satisfactory call quality. Maximum capacity is achieved when Eb/No of every user is at the minimum level needed for the acceptable channel performance. As the mobile station (MS) moves around, the radio frequency (RF) environment continuously changes due to fast and slow fading, external interference, shadowing, and other factors. The aim of the dynamic power control is to limit transmitted power on both the links while maintaining link quality under all conditions. Additional advantages are longer mobile battery life and l...
A simplified generic optimum power control scheme for CDMA cellular systems
Power control is of great importance in reducing cochannel interference and increasing the capacity of mobile telecommunications systems. The aim of optimum power control procedure is to achieve a maximum carrier-to-interference ratios (CIR) in all active communication links (i.e. CIR balancing). Optimum power control with CIR balancing has been widely studied for frequency-division/time-division multiple access (FDMA/TDMA) cellular systems. In these systems, the CIR-balanced optimum power control was transformed to an eigenvalue problem using link-gain matrix. The same method was proposed to CDMA systems. However, the size of the link-gain matrix is proportional to the square of the number of communication links in the system. Thus, the computation of the eigenvalue may be infeasible in CDMA systems with high load. Moreover, optimum power control has never been studied in crossed slots where some mobiles are active in downlink and other in uplink. A simplified optimum power control...
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.
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 ...
In the cellular communication applications of Code Division Multiple Access (CDMA) system, each user signal can be received in the different power levels in the input of the base station due to different distances of the users. In that case, signal of the user that is closer to the base station increases the communication errors of the far users. To solve this problem, open or closed loop power control system is used to make each user signal equals in the input of the base station. Power prediction and power control have been performed with various methods in the literature. In this study, two different methods will be investigated and will be compared with each other in terms of power control performance. The power at the output of the matched filter is predicted using neural network and fuzzy inference system, power control is realized according to the predicted values.
An Efficient Multiobjective Power Control Algorithm for Wireless Cdma Networks
Modares Journal of Electrical Engineering, 2015
1. Department of Electrical Engineering, University of Birjand, Birjand, Iran. m_rezaie_2005@yahoo.com. 2.Assistant professor Department of Electrical Engineering, University of Birjand, Iran.hfarrokhi@birjand.ac.ir. Abstract This paper presents a multiobjective power control algorithm that updates the transmitted power based on local information. The proposed algorithm is expanded by using multiobjective optimization schemes. The objectives to be optimized in this paper are determined so as to reduce the SINR fluctuations as well as maintaining the SINR to an acceptable level with minimizing an average transmitted power. The convergence properties of the proposed algorithm are studied theoretically and with numerical simulations. The results indicate that the algorithm converges more rapidly and has lower average transmitted power than other existing algorithms. The current study also suggests a practical version of the proposed algorithm and compares it to the existing totally dis...