Method for performing adaptive subcarrier allocation to a mobile terminal for FDM or OFDM transmission in a multi cell network, a base station, a mobile terminal and a multi cell network therefor

Abstract

The invention concerns a method for performing adaptive subcarrier allocation to a mobile terminal (T1-T4) for OFDM or FDM transmission in a multi cell network (CN), whereby transmit powers of base stations (BS1-BS8) are estimated, channel transfer functions are calculated based on measurements in the mobile terminal (T1-T4) of pilots transmitted from base stations (BS1-BS8), the transmit powers are weighted with the channel transfer functions, a signal power and an interference power received in the mobile terminal (T1-T4) are estimated based on said weighted transmit powers, a signal to interference ratio is estimated based on the estimated signal and interference power received in the mobile terminal (T1-T4), and the adaptive subcarrier allocation is based on the signal to interference ratio of the subcarriers experienced by the mobile terminal (T1-T4), a base station (BS1-BS8), a mobile terminal (T1-T4) and a multi cell network (CN) therefor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be explained further making reference to the attached drawings.

FIG. 1 schematically shows a multi cell network in which the invention can be implemented.

FIG. 2 schematically shows the desired signal channel transfer function Hd(f) and interfering channel transfer functions Hi1(f) and Hi2(f) from two dominant interfering base stations.

Claims

1. A method for performing adaptive subcarrier allocation to a mobile terminal for OFDM or FDM transmission in a multi cell network, wherein transmit powers or spectral power distributions of base stations are estimated,channel transfer functions are calculated based on measurements in the mobile terminal of pilots transmitted from base stations,the transmit powers or the spectral power distributions are weighted with the channel transfer functions,a signal power and an interference power received in the mobile terminal are estimated based on said weighted transmit powers or the spectral power distributions,a signal to interference ratio is estimated based on the estimated signal and interference power received in the mobile terminal,and the adaptive subcarrier allocation is based on the signal to interference ratio of the subcarriers experienced by the mobile terminal.

2. A method according to claim 1, wherein an upper worst case or a mean value is assumed for the transmit powers of the base stations or of subcarriers or spectral parts used by the base stations (BS1-BS8) for user multiplexing.

3. A method according to claim 1, wherein interference that stems from farther distant interfering base stations is assumed to be white and contributes with a frequency-independent fraction to the signal to interference ratio.

4. A method according to claim 1, whrein the estimation of the transmit power or the spectral power distribution of an interfering base station takes into account the power of the pilots sent by said interfering base station.

5. A method according to claim 1, wherein the estimation of the signal to interference ratio takes into account the thermal noise estimate.

6. A method according to claim 1, wherein the estimation of the transmit powers or the spectral power distributions of base stations takes into account restrictions of the transmit powers or the spectral power distributions due to interference coordination schemes.

7. A method according to claim 6, wherein the identification of cell specific restrictions of the transmit powers or the spectral power distributions due to interference coordination schemes, whereby the restrictions depend on cell identifications, is supported by path loss measurements.

8. A method according to claim 6, wherein the adaptive subcarrier allocation takes into account that restrictions of the transmit powers or spectral power distributions of base stations due to interference coordination schemes lead to more reliable signal to interference ratios in frequency regions with restrictions of the transmit powers or spectral power distributions of base stations.

9. A mobile terminal for performing adaptive subcarrier allocation to a mobile terminal for OFDM or FDM transmission in a multi cell network, wherein the mobile terminal comprises means for calculating channel transfer functions based on measurements in the mobile terminal of pilots transmitted from base stations,the mobile terminal comprises means for weighting the estimated transmit powers or spectral power distributions of the base stations with the respective channel transfer function to estimate the signal and the interference power received in the mobile terminal,the mobile terminal comprises means for estimating the signal to interference ratio based on the estimated signal and interference power received in the mobile terminal,and the mobile terminal comprises means for sending the estimated signal to interference ratio to its serving base station.

10. A base station for performing adaptive subcarrier allocation to a mobile terminal for OFDM or FDM transmission in a multi cell network, wherein the base station comprises means for performing adaptive subcarrier allocation based on the signal to interference ratio of the subcarriers experienced by mobile terminals.

11. A multi cell network comprising base stations for performing adaptive subcarrier allocation to a mobile terminal for OFDM or FDM transmission in a multi cell network, wherein the base station comprises means for performing adaptive subcarrier allocation based on the signal to interference ratio of the subcarriers experienced by mobile terminals and mobile terminals for performing adaptive subcarrier allocation to a mobile terminal for OFDM or FDM transmission in a multi cell network, wherein the mobile terminal comprises means for calculating channel transfer functions based on measurements in the mobile terminal of pilots transmitted from base stations,the mobile terminal comprises means for weighting the estimated transmit powers or spectral power distributions of the base stations with the respective channel transfer function to estimate the signal and the interference power received in the mobile terminal,the mobile terminal comprises means for estimating the signal to interference ratio based on the estimated signal and interference power received in the mobile terminaland the mobile terminal comprises means for sending the estimated signal to interference ratio to its serving base station for performing a method according to claim 1.