Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
1999-08-27
2001-05-22
Nguyen, Lee (Department: 2683)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S436000, C455S442000, C455S517000, C455S524000, C455S525000, C455S069000, C370S332000
Reexamination Certificate
active
06236865
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method of operating a cellular telecommunication system wherein one mobile station communicates with a number of base stations in a macrodiversity mode, and wherein each of the base stations receives a transmission power control signal from the mobile station requesting an increase or a decrease of the transmission power levels. The invention also relates to a corresponding cellular telecommunication system.
In Direct Sequence Code Division Multiple Access (DS-CDMA) cellular telecommunication systems, a mobile station communicates in a so-called macrodiversity mode with a number of base stations. In order to keep the signal qualities of the CDMA signals received by the mobile station from the base stations as constant as possible and at least similar, an inner-loop transmission power control is established. This control creates transmission power control (TPC) signals which are sent from the mobile station to the different base stations. Due to different propagation conditions, e.g. different distances between the base stations and the mobile station, these TPC signals are often received or detected incorrectly by the base stations. This has the consequence that the transmission power levels of the base stations drift apart over the time which is called the random walking problem.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method for operating a telecommunication system which ensures that the transmission power levels of the base stations do not drift apart.
For a method as described above, this object is solved according to the invention in that a primary signaling signal is created by the mobile station indicating that one of the base stations from which the mobile station receives a signal with the highest signal quality, that the primary signaling signal is sent from the mobile station to the base stations, and that the transmission power levels of the base stations are increased and/or decreased depending on the primary signaling signal. For a telecommunication system as decribed above, this object is solved accordingly by the invention.
On the basis of the primary signaling signal, the base stations are able to check which one of them sends the signal with the highest signal quality. This so-called primary base station changes, i.e. increases or decreases its transmission power levels differently compared to the other base stations. This different change has the consequence that a kind of “power race” is performed by the base stations in which different ones of the base stations may become the primary base station. This consecutive change of the primary base station results in the fact that the transmission power levels of the base stations do not drift apart but remain within only small variations. The random walking problem, therefore, is not present anymore.
In an advantageous embodiment of the invention, the transmission power level of that base station being indicated by the primary signaling signal, is decreased by a greater value than the transmission power level of other base stations. In another advantageous embodiment of the invention, the transmission power level of that base station being indicated by the primary signaling signal, is increased by a smaller value than the transmission power level of other base stations.
Both embodiments ensure that the transmission power level of the primary base station is changed in such a manner that—at least after a while—the transmission power level of another base station becomes greater so that this other base station becomes the new primary base station. The “power race” between the base stations is thereby guaranteed with the result that the transmission power levels of the base stations remain about the same and do not drift apart.
It is advantageous when the primary signaling signal is created by comparing the signals received from the base stations. Furthermore, it is advantageous when the signals are compared before being combined. These features provide a fast and simple way to create the primary signaling signal in the mobile station.
REFERENCES:
patent: 5056109 (1991-10-01), Gilhousen et al.
patent: 5267262 (1993-11-01), Wheatley, III
patent: 5530917 (1996-06-01), Andersson et al.
patent: 5559790 (1996-09-01), Yano et al.
patent: 5640414 (1997-06-01), Blakeney, II et al.
patent: 5710981 (1998-01-01), Kim et al.
patent: 5845212 (1998-12-01), Tanaka
patent: 5884187 (1999-03-01), Ziv et al.
patent: 5933782 (1999-08-01), Nakano et al.
patent: 5982760 (1999-11-01), Chen
patent: 6119018 (2000-09-01), Kondo
patent: 0 680 160 A2 (1995-11-01), None
patent: WO 98/56120 (1998-12-01), None
patent: WO 98/56200 (1998-12-01), None
Alcatel
Nguyen Lee
Nguyen Simon
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Operating a cellular telecommunication 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 Operating a cellular telecommunication system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Operating a cellular telecommunication system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2510073