Simulation Analysis of Adaptive Power Control Method in TD-SCDMA System (original) (raw)
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Design of the Power Control Module of TD-SCDMA in Fast Fading Channels
The International Conference on Electrical Engineering
Power Control is essential for CDMA based Mobile Communication Systems. Power Control treats the near far problem, enhances the coverage and the capacity and overcomes fading. Adaptive Power Control improves the system performance in case of severe fading conditions. This paper considers the design of the Power Control module of TD-SCDMA system in fast fading condition. A closed loop adaptive step size power control algorithm is suggested. The proposed power control module can be easily implemented within the TD-SCDMA chipset.
Novel adaptive step power control algorithm for 3G WCDMA cellular system
… , 2009. ICCIT'09. 12th …, 2009
Power control is an essential radio resource management method in CDMA cellular communication systems, where co-channel and adjacent-channel interferences are the primary capacity limiting factors. Power control intends to control the transmission power levels in such a way that required quality of service for the users is guaranteed with lowest possible transmission powers. In this paper, a modulation of power control algorithm is proposed for the 3G WCDMA system. The algorithm is figured on a modification of the transmitted power update step size. Instead of the fixed value presently suggested, the step size is modified dynamically in order to obtain more adapted power variations as well as the step is also represented as a function of the difference between the target and estimated SIR of the MS to obtain more stability of the system. A general form of this algorithm is presented and it is then studied in a simple simulation. Performance of the algorithm was evaluated with the outage percentage, which is the percentage of the number of MS's whose received SIR falls below the fixed threshold. The focused requirement, which had been tried to achieve by this algorithm, is the stability, which was studied and represented through simulation.
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.
Modified Variable Step Size Power Control Algorithm for CDMA Systems
2012
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.
IET Communications, 2011
In this article, we study the power control (PC) process in wireless cellular code division-multiple access systems under flat fading and propose a novel approach to find an optimum step size for closed-loop power control algorithms. In this approach, an optimum step size will be computed from a proposed function. This function depends on system parameters such as, the number of co-channel users, processing gain, the period of PC, Doppler frequency, channel attenuation and the order of diversity. Based on this computation, the mobile station (MS) adjusts its transmit power optimally to decrease interference for other co-channel users. Simulation results for different sets of system parameters show that the proposed algorithm decreases the bit error rate, the outage probability at the base station (BS), and increases the battery life of the MS compared with other values of the step size. The performance of the proposed algorithm is compared with the fixed-step-size power control algorithm and superiority of its performance is confirmed by simulation results. Moreover, the upper and lower bounds of the outage probability and the received signal-to-interference ratio for the proposed algorithm at the BS will be calculated.
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.
A Power Control Algorithm for 3G WCDMA System
In this paper, an evolution of the power control algorithm is proposed for the third-generation WCDMA system. The algorithm is based on a modification of the transmitted power update step size. Instead of the presently-suggested fixed value, the step size is modified dynamically in order to guarantee more adapted power variations. The proposed algorithm is justified and a general form of this algorithm is presented. It is then studied in a simple simulation, which allows useful discussion and evaluation of the proposed algorithm. Important elements of the proposed algorithm are highlighted.
A Comparative Investigation on WCDMA Power Control Mechanisms
2011
The main purpose of this research is to highlight the problems and advantages of both the power control mechanism and compare them accordingly. It has been investigated that open loop system is faster as compared to the close loop system as it has no long procedure or computations. It just have to compare the powers of MS (mobile station) and BS (base station) and increase / decrease the power. The present research mainly focuses on the comparison of WCDMA power control methods including, open and close loop methods, it further focus on channel transmission and signal-to-interference ratio (SIR). The channels used in controlling of power of WCDMA mobile networks are also investigated. Open loop power control has the limitations as it uses the same properties for both the directions of transmission as this is not the case every time practically or on the field. On the other hand close loop power control mechanism has a delay of 1/1.5 kHz (667 microseconds) but it is reliable because ...
Adaptive power control algorithm for 3G cellular CDMA networks
2004 IEEE 59th Vehicular Technology Conference. VTC 2004-Spring (IEEE Cat. No.04CH37514)
In this paper, we study adaptive power control algorithms for the Universal Mobile Telecommunications System (UMTS) and we propose an evolution for these algorithms. The proposed algorithm can be used in both link directions of the Frequency Division Duplex (FDD) mode and in the downlink of the Time Division Duplex (TDD) mode of UMTS, where the same closed-loop power control is used. Unlike the standardized closed-loop power control algorithm of UMTS, adaptive power control algorithms have a dynamic transmitted power update step. For these algorithms, power control steps depend on the instantaneous mobile command and the command history. Our proposed algorithm adds Some intelligence to mobiles and base stations in order to limit oscillations around the target signal-to-interference ratio (SIR). When the received S I R is close to the target SIR, the receiver sends alternative up and down commands. These alternatives commands are interpreted by the transmitter. In this case, the transmitter stabilizes its transmitted power. Simulations
Adaptive Closed-Loop Power Control Algorithms for CDMA Cellular Communication Systems
IEEE Transactions on Vehicular Technology, 2004
Power control has been widely studied and shown to be crucial for the capacity and performance of direct-sequence code-division multiple-access (DS-CDMA) systems. Practical implementations typically employ fast closed-loop power control, where transmitters adjust their transmit powers according to commands received in a feedback channel. The loop delay resulting from the measurements, processing, and transmission of the power control commands can result in oscillations of the transmission powers and lead to degradation in the system performance. In this paper we present new adaptive closed-loop power control algorithms that are able to alleviate the effect of the loop delay. The algorithms are based on self-tuning controllers designed for a log-linear model of the power control process. We carried out computational experiments on a DS-CDMA network using the distributed constrained power control (DCPC) as a reference algorithm. Practical versions of the algorithms are also provided and they were compared with the fixed-step power control (FSPC) algorithm employed in the IS-95 and WCDMA systems. The numerical results indicate that our algorithms can significantly improve the radio network capacity without any increase in power control signaling.