METHOD FOR MINIMISING INTERFERENCE IN A CELLULAR OFDM COMMUNICATIONS SYSTEM AND BASE STATION AND MOBILE STATION FOR THIS

Abstract

The invention concerns a method for minimising the interference in a cellular OFDM communication network (CN), wherein mobile stations (T1-T4) are divided into groups according to the radio channel quality (RCQTvec), the interference levels (NLTvec) of mobile stations (T1, T2) which belong to a first group of mobile stations (T1, T2) with a radio channel quality (RCQTvec) which is lower than that of at least one other group are combined into a common interference level (NLGvec), the sub-carriers (SC) of the OFDM communication network (CN) are divided into quantities according to the common interference level (NLGvec) of the first group of mobile stations (T1, T2) and sub-carriers (SC) which belong to a first quantity with a common interference level (NLGvec) which is lower than that of at least one other group are selected as preferred sub-carriers for transmission to the mobile stations (T1, T2) that belong to the first group, and a base station (BS1) and mobile station (T1-T4) for this.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below with reference to the enclosed drawings.

FIG. 1 shows an example of a cellular communication network in which the invention can be implemented.

FIG. 2 shows as an example the performance of the method according to the invention by the transmission of information on interference level and radio channel quality from the mobile stations to the base station.

FIG. 3 shows as an example the principle of the method according to the invention for the selection of sub-carriers on which transmission is to take place with reduced power.

FIG. 4 shows diagrammatically the various levels of processing of information on interference level and radio channel quality.

Claims

1. Method for minimising interference in a cellular OFDM communication network, wherein mobile stations allocated to a cell measure the radio channel quality and the interference level as a function of the individual sub-carriers and transmit these to the base station of the cell,the radio channel quality is combined into a radio quality parameter for each mobile station,the mobile stations are divided into groups according to the radio quality parameter,the interference level of mobile stations which belong to a first group of mobile stations with a radio quality parameter that is lower than that of at least one other group, are combined into a common interference level,the sub-carriers of the OFDM communication network are divided into quantities according to the common interference level of the first group of mobile stations,and sub-carriers which belong to a first quantity with a common interference level which is lower than that of at least one other quantity, are selected as preferred sub-carriers for transmission to the mobile stations which belong to the first group.

2. Method according to claim 1, wherein sub-carriers which belong to a second quantity with a common interference level which is higher than the common interference level of sub-carriers of the first quantity, are selected as preferred sub-carriers for use with reduced transmission power.

3. Method according to claim 1, wherein the interference level of mobile stations which belong to a second group of mobile stations with a radio quality parameter that is higher than that of the first group, are combined into a common interference level of the second group of mobile stations,the sub-carriers of the OFDM communication network are divided into quantities according to the common interference level of the second group of mobile stations,sub-carriers which belong to a quantity with a common interference level of the second group of mobile stations which is lower than the common interference level of at least one other quantity, are compared with sub-carriers which belong to a quantity with a common interference level of the first group of mobile stations that is higher than the common interference level of sub-carriers of at least one other quantity,and selected as preferred sub-carriers for use with reduced transmission power are those sub-carriers which belong only to the quantity with a common interference level of the first group of mobile stations that is higher than the common interference level of sub-carriers of at least one other quantity.

4. Method according to claim 1, wherein the interference level of mobile stations which belong to a second group of mobile stations with a radio quality parameter that is higher than that of the first group are combined into a common interference level of the second group of mobile stations,the sub-carriers of the OFDM communication network are divided into quantities according to the common interference level of the second group of mobile stations,sub-carriers which belong to a quantity with a common interference level of the second group of mobile stations which is higher than the common interference level of at least one other quantity, are compared with sub-carriers which belong to a quantity with a common interference level of the first group of mobile stations that is higher than the common interference level of sub-carriers of at least one other quantity,and selected as preferred sub-carriers for use with reduced transmission power are those sub-carriers which belong to both quantities.

5. Method according to claim 1, wherein the sub-carriers for use with reduced transmission power are selected at random from sub-carriers which do not belong to a first quantity.

6. Method according to claim 2, wherein from the preferred sub-carriers are selected for use with reduced transmission power those sub-carriers which have the highest common interference level.

7. Method according to claim 2, wherein from the preferred sub-carriers are selected for use with reduced transmission power those sub-carriers which have the poorest common radio channel quality.

8. Base station in a cellular OFDM communication network, wherein the base station has means for combining the radio channel quality into a radio quality parameter for a mobile station,dividing the mobile stations into groups according to the radio quality parameter,combining the interference level of mobile stations which belong to a first group of mobile stations with a radio quality parameter that is lower than that of at least one other group, into a common interference level,dividing the sub-carriers of the OFDM communication network into quantities according to the common interference level of the first group of mobile stations,and selecting sub-carriers which belong to a first quantity with a common interference level which is lower than that of at least one other quantity, as preferred sub-carriers for the transmission to the mobile stations which belong to the first group.

9. Mobile station in a cellular OFDM communication network, wherein the mobile station comprises means for measuring the radio channel quality and the interference level and transmitting these to the base stations of its allocated cells.