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Uplink channel power control improvement in DS-CDMA system using channel predictions

Othman , Ibtesam. A. (2013) Uplink channel power control improvement in DS-CDMA system using channel predictions. Masters thesis, Universiti Tun Hussein Onn Malaysia.

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Abstract

In cellular systems all Mobile’s Station (MS) signals should arrive to Base Station (BS) at equal power, if not the weaker one will be blocked and the strong signals will interference with each other. The research areas include coding and improving power control for uplink channel schemes in cellular systems. Commonly the uplink channel power control schemes utilizes Signal to Interference Ratio (SIR) to design a Power Control Command (PCC) to adjust the transmit power of the mobile station in cellular systems. Conventional SIR based uplink channel power control schemes updates the transmitting power based on the current channel state, in the fact the state of channel will be changed when the transmission is made; the channel is already in its next state. The state is different from previous one. That causes the SIR to drop or rise drastically and lead to Near-Far effect interference resulting in power escalation and making the DS-CDMA system go unstable. To overcome these problems, a new approach method has been developed, based on linear quadratic Gaussian (LQG) control and Extended Kalman filter for channel prediction, this method dependent on the channel state instead of the current. Using the proposed method the next state of uplink channel can be predicted and update the power accordingly. This will give us a more stable SIR behavior and leads to stable DS-CDMA system. The simulation of this research is performed using Matlab to show the result of building a DS-CDMA system link with existing SIR based uplink channel power control schemes, implementing the predictive approach for uplink channel power control achieved the signal to interference ratio (SIR) as close as possible to the predefine level in order to maximize a DS-CDMA systems capacity and performance. That is clearly shown in the results when compared with the conventional methods.

Item Type: Thesis (Masters)
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5101-5865 Telecommunication. Telegraph.
Depositing User: Normajihan Abd. Rahman
Date Deposited: 05 Jan 2016 01:11
Last Modified: 05 Jan 2016 01:11
URI: http://eprints.uthm.edu.my/id/eprint/3647
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