Telecommunications – Transmitter – With feedback of modulated output signal
Patent
1997-09-16
2000-08-15
Eisenzopf, Reinhard J.
Telecommunications
Transmitter
With feedback of modulated output signal
455 69, 455572, H01Q 1112
Patent
active
061049182
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The invention relates to a method for controlling transmitting power in a radio system comprising one base station or several base stations communicating with subscriber terminal equipments located within its area, in which method the transmitting power of the equipments is controlled stepwise by power control commands and the step size of a change in transmitting power is adjusted separately for each connection.
PRIOR ART
It is typical of a cellular radio environment that the Propagating conditions of radio waves vary constantly. Both in a signal received by a subscriber terminal equipment and in a signal received by a base station, constant variation, i.e. fading, occurs. In fading of the signal, two different types of phenomena may be distinguished. Fading may be either fast or slow and both phenomena usually occur simultaneously.
Fast fading of a signal is caused by multi-path propagation typical of a cellular radio environment, where a signal propagates along several different routes between a transmitter and a receiver. Signal components arriving at the receiver different ways are summed in the receiver, and depending on the mutual phase differences between the signal components, they either amplify or attenuate each other. The level of the signal may vary considerably, up to dozens of decibels, along a distance of less than half a wavelength already.
Slow fading of a signal, in turn, is caused by the fact that, on the radio path, there is a varying number of factors causing additional attenuation, such as natural obstacles or buildings. The effect of slow fading on the signal consists, as its name suggests, of one grade slower variation in the signal strength than that caused by fast fading, which causes strong power variations around the envelope curve caused by slow fading.
Due to the above-mentioned constant strength variation of the received signal, the transmitting power used by a subscriber terminal equipment and a base station must be monitored continuously and efforts must be made to control it suitable at each moment of time. The aim of power control is to keep the transmitting power of the device as low as possible, still maintaining a sufficient quality of a connection so that the signal will not interfere with other connections and so that the power consumption of a portable terminal equipment in particular will be small.
Controlling the transmitting power is generally based on monitoring the power of the received signal to be carried out in the receiver. The control may be implemented for instance by means of power control messages transmitted by a controlling device to the transmitter to be controlled. A power control message comprises an instruction for increasing or decreasing the transmitting power by some power quantity or step.
As an example of an implementation of power control according to prior art is presented the International Patent Application PCT/US92/04161 "Method and apparatus for controlling transmission power in a CDMA cellular mobile telephone system". In the method according to the publication, power control messages are utilized, by which the transmitting power of the transmitter to be controlled is decreased or increased stepwise. In the present solution, the step size is constant.
Keeping the step size of the power control constant causes problems in situations in which the signal or the interference level change from time to time, but still not continuously. Such a situation arises in a WLL (Wireless Local Loop) system, for instance, where the subscriber terminal equipments are fixedly located or changes in signal level are generally rather small. On the other hand, changes in interference level at times cause even great changes in the signal-to-interference ratio.
If the power control of a radio system is carried out by means of a large fixed step size, the problem is a strong fluctuation of the used power around the desired power level. This concerns particularly the WLL system, in which channel changes usually are small. On the other ha
REFERENCES:
patent: 5129098 (1992-07-01), McGirr et al.
patent: 5524287 (1996-06-01), Yokoya et al.
patent: 5574993 (1996-11-01), Kobayashi et al.
patent: 5689815 (1997-11-01), Yamazaki et al.
Su, et al. "Reverse-Link Power Control Strategies for CDMA Cellular Network", IEEE, 1995, pp. 461-465.
Chang, et al. "Adaptive Fuzzy Power Control for CDMA Mobil Radio Systems", 1994 International Symposium on Artificial Neural Networks, ISAAN'94, 757-763, Taiwan.
Saario Eija
Salonaho Oscar
Bhattacharya Sam
Eisenzopf Reinhard J.
Nokia Mobil Phones Ltd.
Nokia Telecommunications Oy
LandOfFree
Method for controlling transmitting power and radio system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for controlling transmitting power and radio system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for controlling transmitting power and radio system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2017179