Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Patent
1996-04-03
1998-06-30
Le, Thanh Cong
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
455440, 455452, 455 63, 370332, 375202, H04Q 700
Patent
active
057748080
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/F195/00412 filed Aug. 2. 1995.
BACKGROUND OF THE INVENTION
The invention relates to a method for allocating radio channels in a cellular communication system, each cell comprising at least one base station communicating with the subscriber terminal equipment within its area by means of a traffic channel specific for each connection, in which method the base station monitors the quality of the available traffic channels.
In cellular communication systems the quality of the connection between the base station and the subscriber terminal equipment varies as a function of time and location. On average, the more remote the terminal equipment is from the base station, the more signal attenuation occurs on the radio path, but other factors, such as visual obstructions and external interferences also affect the quality of the signal at the receiving end.
The attenuation of the signal also depends on the used frequency. Thus, if the frequency difference between two signals is sufficient, their attenuations do not correlate. For instance, a frequency difference of 1 MHz is sufficient, so that the attenuations of the signals are independent of each other. Due to this frequency-selective attenuation, several cellular communication networks have introduced the frequency hopping technique. This means that the frequency used on the connection is varied at predetermined intervals. Thus, the effect of the frequency-selective attenuation may be averaged, and similarly, the harmful effect of narrowband interference signals on the desired signal is reduced.
In several systems, part of the channels used by the base station are frequency hopping and part of the channels use fixed frequencies. This is necessary since some of the signalling channels must be transmitted on a certain frequency, so that the terminal equipment can find them. Owing to this, among other things, various traffic channels of the base station may have quite different interference levels.
In present systems, when a traffic channel is being allocated for the connection between a terminal equipment and the base station, either in connection with call set-up or handover, those traffic channels are searched from the available traffic channels of the base station which are currently free, and their Idle Channel Interference level is checked. One of those idle channels with the lowest interference level is randomly allocated for the use the terminal equipment.
The drawback of the method described above is that it does not take into account the different character of various channels and the conditions in which each terminal equipment currently exists. The characteristics of various channels are thus not utilized in the best possible way.
SUMMARY OF THE INVENTION
The object of the present invention is thus to implement a new method for channel allocation, with which method the above-mentioned drawbacks may be avoided, and the service ability of the cellular communication system may thus be improved.
This is achieved with a method of the type set forth in the foregoing BACKGROUND section, which is characterized in that upon selecting the traffic channel for the connection between the base station and the terminal equipment, the quality of the connection required by the terminal equipment and the interference level of each possible traffic channel are taken into account.
The method of the invention may be particularly applied so that an attempt is made for providing the connection to be established simply a sufficiently good radio channel. The radio channels may be classified on the basis of the interference level obtained by means of measurements, and of the effect of frequency hopping. A traffic channel enabling a high quality of the connection may be given to a terminal equipment behind a poor connection, whereas, for instance, a traffic channel containing more interference may be given to a terminal equipment located near the base station, since the quality of the connection is sufficient in
REFERENCES:
patent: 5287544 (1994-02-01), Menich et al.
patent: 5293643 (1994-03-01), Israelsson
patent: 5327576 (1994-07-01), Uddenfeldt et al.
patent: 5375123 (1994-12-01), Anderson et al.
patent: 5381443 (1995-01-01), Borth et al.
patent: 5603092 (1997-02-01), Stjernholm
Sarkioja Juha
Suonvieri Jukka
Cong Le Thanh
Nokia Telecommunications Oy
LandOfFree
Method for channel allocation in a cellular communication 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 channel allocation in a cellular communication system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for channel allocation in a cellular communication system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1871823