Reconfiguration is performed according to the prediction of the channel attenuation and the threshold set at the bs or ms based on its channel power probability density function. Pa modules the device is active for enable hi, otherwise it is in a low power consumption shutdown mode. Fredrik gunnarsson and fredrik gustafsson, control theory aspects of power control in umts, control engineering practice, volume 11, issue 10, pages 111125, october 2003. A wcdma system includes a base station bs transmitter, or forward transmitter and a pilot channel that transmits control signals between the bs and a mobile station ms to reconfigure their transmitterreceiver. Third edition edited by harri holma and antti toskala both of nokia, finland. To solve the nearfar problem to increase the system capacity wcdma uses two tpc forms. Power control in wcdma broadcast engineering radio. Simulation results indicate that fractional power control is advantageous compared to the conventional open loop power control in terms of mean cell throughput. Wcdma is a promising technique for achieving the high data capacity and spectral efficiency requirements for wireless communication system of the near future. The demand for high speed mobile wireless communication is rapidly growing. In conclusion, power control is extremely important in umts. By doing that the rapid change in the radio channel is handled. Quintero department of electronic systems aalborg university a thesis submitted for the degree of. Characterization of downlink transmit power control during.
Todays post continues the discussion with reference to hsdpa and hsupa. To ensure good performance, power control is implemented in both the uplink and the downlink, which means that both the output powers of the handset and the base station are frequently. Openloop power control is used on physical channels. So algorithm 2 is applicable when the environment of mobile environment is quite favourable and the channel fades slowly or hardly fade.
Let us take example of cdma system wherein there is dedicated pilot channel provided for channel estimation. Power control is an important feature of a wcdma system. Therefore, it causes oscillations when the radio channel is unchanged. Uplink power control determines the average power over a dftsofdm symbol in which the physical channel is transmitted. Open loop power control vs closed loop power control. Wcdma system standardization, interfaces and power control. Last week i wrote about umts power control with reference to r99 channels. Characterization of downlink transmit power control during soft handover in wcdma systems palash gupta, hussain mohammed, and m. This project tries to introduce itself in the physical implementations that make\ud possible the denominated third generation mobile technology. Wcdma wideband code division multiple access plays the best competitive role in the present world. To adjust the radiated power of mobile stations in a way that all received signals at the base station have the same sir for the same bit rate to reduce cochannel interference by concurrent users. Power control is essential for the smooth operation of a cdma system. Umts power control algorithm is based on fixed step size. Sirbased fast closed loop tpc open loop tpc zeon pdf driver trial tw.
In contrast to utran based on wcdma however the requirements for ul power control are more relaxed as a similar nearfar problem of utran does not exist. In this paper, an evolution of the power control algorithm is proposed for the thirdgeneration wcdma system. With algorithm 2, the inner loop power control is performed every five timeslots, that is, the frequency is lower to perform inner loop power control in algorithm 2. In this paper i will discuss about wcdma system, to know it is standardization, it is interfaces and power control. Advanced power control for utran lte uplink nestor j. The umts world is an 3g mobile system news and information provider.
Why is there no power control scheme in downlink for lte. The design contains a lot of flexibility to allow power control at different levels. At the start of the call phone uses reasonably high power settings and then. In order to maintain the received level at bs, a suitable power control technique must be employed in cdma systems. Its main objective is to ensure a satisfactory signalto interference ratio at the receiver for all links in the system. Wcdma has an e cient power control mechanism that updates the power level in every 1500 seconds 1. The mobile unit measurement is part of the open loop power control while the base station measurement is part of the closed loop power control. There are two ways to control the transmission power. Performance analysis of downlink power control in wcdma system dr. Wcdma for umts radio access for third generation mobile communications. Umts through wcdma can be summarized like a revolution of the air. In lte, power control takes place both in downlink and uplink. Introduction power control is a crucial radio network function in cellular systems. Power control in wcdma free download as powerpoint presentation.
Power control is essential in wcdma systems to provide satisfactory quality of service qos and to combat several problems. This control is called the transmission power control control power. R99 uplink power control uplink power control means change of uplink power based on tpc command carried by downlink control channeldl dpcch. Measuring the rf power in cdma2000 and wcdma high power. When we study a new technology one of way to efficiently learnunderstand about it would be to assume that you are the designerdeveloper of the technology and ask yourself now i have this and this problem in such and such situation. A typical power amplifier for cdmawcdma cell phones. In the wcdma system, the power control mechanism comprises the following parts. Hsdpa does not have fast power control as in r99 dl dpch. The algorithm is based on a modification of the transmitted power update step size. Cdma rf power control combination with a directional coupler. When the ue is not in soft handover, only one tpc command is received in each timeslot. A hashem department of computer science and engineering. Power control is important aspects of wcdma system.
The lmv226 is equipped with a buffered output which makes it wcdma rf power control suitable for gsm, edge, gprs and tdma cdma2000 rf power control applications. This power can be set very accurately, and its level can be changed using an analog voltage controlled by an adc. They way it takes place in downlink and uplink will become evident in a little bit, as we go further down the discussion. Because all users share the same rf band through the use of pn codes each user looks like random noise to other users. In this paper, we propose a new adaptive power control algorithm for in umts. As you see in the figures below, both downlink dpcch and uplink dpcch slot has a special field called tpc transmission power control field. Reducing v ref when transmitting zero rf power, the pa itself draws a typical quiescent current of 100ma at v ref 3. Table of contentschapter 1 power control1 huawei technologies proprietary i. But other way if students have to speak they have to increase decrease their voice depending on which row they a. Power control tpc transmit power control tpc is essential to a cdma architecture. Teacher need not increase decrease her voice but speak in loud voice so all students can hear her. To improve the performance of the network,soft handover feature is indispensable which allows the communication of users in two di erent cells in two or more di erent base stations.
Comprehesive coverage of umts 3g news, licensing, business developments, 3g wcdma telecommunication technology, multi media mobile phones and future communications. It sets the initial uplink and downlink transmit power. Where things start to get interesting is with the power dynamics. Using a power detector in controller mode to accurately control the input or output power of an hpa would be an ideal application, as it would remove the need to detect the input or output power. Let us begin with hsdpa for which power control is significantly different from r99 channels. Therefore the picture below should explain you on which channels in dl and ul, power control takes place. Rf power reduction for cdmawcdma cellula maxim integrated. It is the process in which cell tower and mobile phone collectively decide which minimum transmission power a phone could safely employ and still be heard by a cell tower. Inner loop power control in the uplink is the ability of the ue to adjust its output power in accordance with one or more tpc transmit power control commands received in the downlink. The future lines that are considered in the present, and other comment that already are in their last phase of development in the field of the mobile technology.
The received level fluctuates quickly due to fading. Power control in wireless cellular networks mung chiang electrical engineering department, princeton university prashanth hande electrical engineering department, princeton university. This implies, ue transmit power will change quite considerably between different subframes in lte uplink. As well as to\ud know the technology kind that makes possible, for example, a videocall in real\ud time. The proposed algorithm can mitigate the oscillations. Scribd is the worlds largest social reading and publishing site. Config rf settings rf power downlink output channel power ior 93. Us6690652b1 adaptive power control in wideband cdma. School khulna university of engineering and technology. In modern cellular communication systems, power control plays a fundamental role for efficient resource utilization. In umts, different power control procedures are used for uplink and downlink physical channels. Compared with utran the ul power control is slower. Furthermore, it lacks abilities to cope with rapid variations in fast fading channels.
We need to control the transmission power of each user. Keywords lte, uplink, power control, fractional power control. This paper describes a wideband code division multiple access test system developed by nokia. In the closed loop mode, the mobile station transmitter power is controlled by a signal from the base station. Further, since the objective of the power control algorithm is to keep the ue power spectral density psd constant, total power transmitted by the ue scales with m. In the open loop power control, there is no feedback either from mobile to bs or from bs to mobile.
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