Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Patent
1996-06-24
2000-06-27
Le, Thanh Cong
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
455 62, H04B 700
Patent
active
060817224
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a mobile radio transmission system with radio base stations and mobile stations.
Mobile radio transmission systems for covering a rather large radio coverage area have been conceived as cellular radio networks for a long time. Each cell of such a radio network comprises at least one radio base station that maintains a radio connection to the mobile stations located in its radio cell. To make the frequency band available for the radio system accessible to the largest possible number of subscribers in the whole mobile radio communications system, great importance is attributed to the radio network planning.
Channel allocation in a mobile radio network is then a difficult problem of the radio network planning. So far this has been solved by making forecasts in the planning phase about the expected traffic density and radio wave propagation. Such calculations then result in numbers of channels necessary for each radio base station and corresponding compatibility requirements of the individual radio base stations. Via suitable computing methods it is then possible to generate channel lists i.e. lists of channels which are to be installed in the radio base stations concerned from these necessary numbers of channels. The disadvantage of such a procedure is that the correctness of the data on which the planning is based is to be trusted and the planning is to be repeated with each change of the network. Especially in the microcell area, this procedure of planning of radio networks is almost inapplicable because, on the one hand, microcells by nature require a degree of detail that can no longer be effectively calculated beforehand and, on the other hand, microcells in a city area are subjected to permanent changes. For example, the shadowing properties of buildings are no longer modelled stochastically as they have been thus far, but the necessary accuracy of the field strength propagation cannot be effectively calculated in advance. On the other hand, for example building sites and traffic jams represent continuous changes of the network. However, since microcells have the only possibility of coping with the present or future dramatic increase of radio subscribers, on the whole the procedure of preliminary planning no longer seems to be practical.
From EP 0 585 994 A2 is known a mobile radio transmission system of the type defined in the opening paragraph.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a possibility of how the channel allocation can be learnt while the network is in operation.
This object is achieved in a mobile radio communications system defined in the opening paragraph in that the mobile radio transmission system comprises means for allocating radio channels in dependence on the radio situation, while the channel allocation is based on the utilization of the Kohonen model.
The invention is then based on the recognition that in a planning step of the mobile radio transmission system it is no longer necessary to calculate the traffic density and compatibility information beforehand. The dynamically learnt channel allocation takes place on a microscopic level. Instead of allocating channel lists per radio base station, as has been done so far (macroscopic level), now a channel list is allocated for each channel situation. A radio situation is now defined by a space-dependent and a time-dependent component. The space-dependent component, the finding place, is determined by the vector of the signal strengths of all the radio base stations and may be interpreted as a sub-cell of the coverage area of a particular radio base station. The time-dependent component, the channel situation, is determined by the traffic of the channel activities of all the channels.
In addition, a real-time channel allocation component is proposed which, while utilizing the channel allocation learnt so far, allocates a channel to a current call in dependence on the current radio situation. It is then assumed that the radio channels of each radio
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patent: 5157709 (1992-10-01), Ohteru
patent: 5475868 (1995-12-01), Duque-Anton et al.
Networks for the Enterprise, NSTL Software Roundup Reviews, Feb. 1995.
Neurale Netze: Eine Einfuhrung in die Neuroinformatik Selbstorganisierender Netwerke by H. Ritter et al, Addison-Welsey 1990.
Duque-Anton Jesus-Manuel
Kunz Dietmar W.
Ruber Bernhard J.
Cong Le Thanh
Halajian Dicran
U.S. Philips Corporation
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