Method for allocating frequencies in a multibeam satellite radiocommunications system, and associated system

Abstract

A method for allocating frequencies in a multibeam satellite radiocommunications system is provided, wherein a geographical service zone covered by the system is broken down into a plurality of cells, distributed into a first grid and a second grid of cells, the cells of the first grid and the cells of the second grid being respectively associated with opposing polarizations of the transmission signals; a cell is broken down into two parts, one part being respectively associated with a colour corresponding to a frequency sub-band and to the polarization of the grid to which it belongs, the total frequency band being broken down into three frequency sub-bands; and two contiguous cell parts of one and the same grid are associated with different colours.

Claims

1. A method for allocating frequencies in a multibeam satellite radiocommunications system, wherein: a geographical service zone covered by the system is broken down into a plurality of hexagonal or square cells, distributed into a first grid and a second grid of cells, the cells of the first grid and the cells of the second grid being respectively associated with opposing polarizations of the transmission signals; a cell is broken down into two parts, one part being respectively associated with a colour corresponding to a frequency sub-band and to the polarization of the grid to which it belongs, the total frequency band being broken down into three frequency sub-bands; and two contiguous cell parts, able to be superimposed, of one and the same grid are associated with different colours.

2. The method according to claim 1, wherein the frequency sub-bands are of the same width, corresponding to a third of the total frequency bandwidth.

3. A system for allocating frequencies in a multibeam satellite radiocommunications system, configured so as to implement the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood upon studying a few embodiments, described by way of entirely nonlimiting example and illustrated by the appended drawings, in which:

(2) FIGS. 1, 2 and 3 schematically show the frequency plans for a two-colour, a four-colour and a fractional frequency reuse FFR colour scheme, according to the prior art;

(3) FIG. 4a schematically illustrates a hexagonal-cell FFR colour scheme, according to the prior art;

(4) FIG. 4b schematically illustrates a square-cell FFR colour scheme, according to the prior art;

(5) FIG. 5a schematically illustrates a hexagonal-cell colour scheme, according to one aspect of the invention;

(6) FIG. 5b schematically illustrates a square-cell colour scheme, according to one aspect of the invention; and

(7) FIG. 6 schematically illustrates the frequency plan for a colour scheme according to FIG. 5a, according to one aspect of the invention.

(8) In all of the figures, elements having identical references are similar.

DETAILED DESCRIPTION

(9) In FIG. 5a, a first polarization state and a second polarization state are respectively allocated to the cells of a first grid G1 and to the cells of a second grid G2.

(10) The hexagonal cells of the first grid G1 are all separated identically into two parts P, which are for example equal. The total frequency band is broken down into three frequency sub-bands, in this case having the same frequency width. Three colours 1, 2 and 3 are allocated for the first grid G1 corresponding to a first polarization state. Each part P of a cell Cell of the first grid G1 is associated with one of the three colours 1, 2 and 3, such that two contiguous cell parts are associated with different frequency sub-bands.

(11) Similarly, the hexagonal cells of the second grid G2 are all separated identically into two parts P, which are for example equal. The total frequency band is broken down into three frequency sub-bands, in this case having the same frequency width and being identical to the breakdown performed for the first grid G1. Three colours 4, 5 and 6 are allocated for the second grid G2 corresponding to a second polarization state, opposite to that of the first grid G1. Each part P of a cell Cell of the second grid G2 is associated with one of the three colours 4, 5 and 6, such that two contiguous cell parts are associated with different frequency sub-bands.

(12) The colours 1, 2, 3 and 4, 5, 6 generally correspond to the same division into frequency sub-bands; only the polarizations are different.

(13) As illustrated in FIG. 5a, in comparison with the hexagonal FFR colour scheme of FIG. 4a, the hexagonal-cell colour scheme according to the invention makes it possible to minimize interfering elements, i.e. to increase the distances between the interfering zones, and makes it possible to reduce the frequency band to be processed ( of the frequency band of the FFR scheme).

(14) In FIG. 5b, a first polarization state and a second polarization state are respectively allocated to the cells of a first grid G1 and to the cells of a second grid G2.

(15) The square cells of the first grid G1 are all separated identically into two parts P, which are for example equal. The total frequency band is broken down into three frequency sub-bands, in this case having the same frequency width. Three colours 1, 2 and 3 are allocated for the first grid G1 corresponding to a first polarization state. Each part P of a cell Cell of the first grid G1 is associated with one of the three colours 1, 2 and 3, such that two contiguous cell parts are associated with different frequency sub-bands.

(16) Similarly, the square cells of the second grid G2 are all separated identically into two parts P, which are for example equal. The total frequency band is broken down into three frequency sub-bands, in this case having the same frequency width and being identical to the breakdown performed for the first grid G1. Three colours 4, 5 and 6 are allocated for the second grid G2 corresponding to a second polarization state, opposite to that of the first grid G1. Each part P of a cell Cell of the second grid G2 is associated with one of the three colours 4, 5 and 6, such that two contiguous cell parts are associated with different frequency sub-bands.

(17) The colours 1, 2, 3 and 4, 5, 6 generally correspond to the same division into frequency sub-bands; only the polarizations are different.

(18) As illustrated in FIG. 5b, in comparison with the square FFR colour scheme of FIG. 4b, the square-cell colour scheme according to the invention makes it possible to minimize interfering elements, i.e. to increase the distances between the interfering zones, and makes it possible to reduce the frequency band to be processed ( of the frequency band of the FFR scheme), i.e. to increase capacity.

(19) FIG. 6 shows the frequency plan for a colour scheme according to FIG. 5a.