Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Patent
1995-07-26
1998-11-17
Mullen, Jr., Thomas J.
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
455 62, 455 63, 455452, H04Q 700
Patent
active
058390740
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a process of allocating frequencies to base stations of a mobile radiotelephone network, which process is based on input information containing at least the number of frequencies required for each base station, the frequencies permissible in the mobile radiotelephone network and information on possible disturbance effects among the base stations in the case of identical and/or adjacent frequencies.
In mobile radiotelephone networks, base stations are distributed over the geographical area which is covered by the mobile radiotelephone network. The base stations comprise transmitting and receiving equipment designed for a communication exchange by way of mobile stations which are located in the service area of the respective base station. Since the number of frequencies that can be used for the mobile radiotelephone network is limited, it cannot be excluded that identical frequencies are assigned to different base stations, which creates interferences if a mobile station receives signals of the same frequency from several base stations. Furthermore, interferences due to closely adjacent frequencies cannot be excluded. Apart from disturbances due to interferences during the reception of the base station signals in the mobile stations (down link), interferences during the reception in the base stations (up link) must also be taken into account.
Therefore, the allocation of frequencies to the individual base stations must be carried out in such a manner that the operation of the mobile radiotelephone network is ensured to have as little interference as possible. For this purpose, different processes have become known in which frequencies are assigned base station by base station, with frequencies being excluded which have already been allocated to another base station, if the interference probability between the base station and the other base station exceeds a predetermined limit value.
In a process disclosed in WO 90/10341, respective maximum groups of base stations are put together successively for the individual frequencies, which base stations had not yet received a frequency and which may all have an identical frequency because of not exceeding minimum requirements. The process is directed at the objective of using as few frequencies as possible.
In a further process (A. Gamst: "A resource allocation technique for FDMA systems" in Alta Frequenza Vol. LVII N. 2), which is used in a computer program that became known under the name of GRAND, respective maximum groups of base station frequency requests that are still pending are formed successively for the individual frequencies. This means that here the case of a base station needing more than one frequency is already considered. If the frequency is fixed, this frequency must be able to simultaneously meet all the frequency requests collected in the group, this means that specific minimum requirements are still complied with. Here, as well, the process is directed at the objective of using as few frequencies as possible. Through an intelligent determination of a minimum number of required frequencies, the process even makes it possible to check if the objective of minimizing the number of frequencies was reached successfully.
In the GLOBECOM 85 report (IEEE Global Telecommunication Conference), a process of allocating channels (frequencies) to cells (base stations) is described. The allocation takes place by selecting a cell (base station) by means of a cell selection criterion. A suitable channel is allocated to the selected cell by means of a channel selection criterion. If a definite selection of suitable cells and/or channels is not successful by way of this selection process, the selection takes place according to a random principle or the allocation is executed by groups, i.e., a channel is assigned to each of the determined cells.
The conventional objective of the known processes, namely minimizing the number of frequencies used, must be questioned. Normally, the operator of a mobile radiotelephon
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Gamst, A., "A Resource Allocation Technique for FDMA Systems", Alta Frequenza, vol. LVII, N. 2, 1988 pp. 89-96.
Hong, D. & Rappaport, S., "Heuristic Channel Assignments for Cellular Land Mobile Radio Systems", IEEE, Global Telecommunications Conf., 1985.
DeTeMobil Deutsche Telekom MobilNet GmbH
Mullen Jr. Thomas J.
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