Measurement in radio communication systems

1. A method for radio channel estimation in a radio communication system, wherein the system comprises at least one mobile station and at least two base stations, each base station having a certain number of sectors and at least one antenna element for each sector, and wherein one of the base stations is a serving base station for the mobile station and the at least one further base station is a neighboring base station of the serving base station, the method comprising:

generating a schedule for measurement signals in the serving base station;

transmitting the schedule from the serving base station to the mobile station;

transmitting in accordance with the schedule measurement signals from the mobile station to the serving base station;

calculating a channel state for an uplink channel from the mobile station to the serving base station;

determining an area around the sector in which the mobile station is located, wherein base stations within the area are neighboring base stations of the serving base station, wherein the at least one neighboring base station schedules measurements for mobile stations connected therewith and wherein at least one subcarrier is allocated to at most one of the mobile stations within the determined area, the at least one neighboring base station configured to distribute the subcarrier allocations within the determined area;

transmitting the schedule from the serving base station also to the at least one neighboring base station;

transmitting the measurement signals from the mobile station also to the at least one neighboring base station;

calculating a mean channel state for the mobile station in the at least one neighboring base station;

transmitting the mean channel state from the at least one neighboring base station to at least one further base station of the radio communication system; and

distributing through the at least one neighboring base station transmit power that mobile stations connected therewith use for their measurement allocation to all other base stations within the determined area,

wherein the serving base station coordinates its measurement with the at least one neighboring base station within a certain range,

wherein all base stations within the range schedule measurement for their mobile stations during the same OFDM symbols and do not schedule any other transmissions during that time.

2. The method according to claim 1 , wherein all neighboring base stations schedule measurements for mobile stations connected therewith and wherein at least one subcarrier is allocated to at most one of the mobile stations within the determined area.

3. The method according to claim 2 , wherein each neighboring base station distributes to all other base stations within the determined area the subcarrier allocations intended for measurement of mobile stations connected therewith.

4. The method according to claim 2 , wherein each neighboring base station distributes to all other base stations within the determined area the transmit power that mobile stations connected therewith use for their measurement allocation.

5. The method according to claim 1 , wherein the transmitting of the measurement signals from the mobile station to the serving base station is repeated regularly.

6. The method according to claim 1 , wherein the calculating of the mean channel state for the mobile station in the at least one neighboring base station is performed by averaging over multiple measurements in frequency and time.

7. The method according to claim 1 , wherein each base station within the determined area distributes the calculated mean channel states to all other base station within the area.

8. The method according to claim 1 , wherein the measurement signals comprise specific symbols and a prefix, wherein a delay of the measurement signals at neighboring base stations, which shall receive the measurement signals, is smaller than a length of the prefix.

9. The method according to claim 1 , wherein the measurement signals comprise specific symbols and a prefix, wherein the specific symbols are extended according to an expected delay of the measurement signals at neighboring base stations, which shall receive the measurement signals.

10. The method according to claim 1 , wherein the measurement signals comprise specific symbols and a prefix, wherein a sampling time for the measurement signals at neighboring base stations is decreased to a certain fraction of a regular sampling time.

11. The method according to claim 1 , wherein the method is implemented as a computer program product for radio channel estimation in a radio communication system, the computer program product comprising a computer readable medium, having thereon computer program coding operative, when the program is loaded, to make a computer executable for carrying out the method.

12. A radio communication system, comprising at least one mobile station and at least two base stations, each base station having a certain number of sectors and at least one antenna element for each sector, wherein one of the base stations is a serving base station for the mobile station and the at least one further base station is a neighboring base station of the serving base station, and wherein:

the serving base station is configured to generate a schedule for measurement signals and to transmit the schedule to the mobile station;

the mobile station is configured to transmit measurement signals in accordance with the schedule to the serving base station; and

the serving base station is configured to calculate channel state for the uplink channel from the mobile station to the serving base station,

wherein:

the serving base station is further configured to determine an area around the sector in which the mobile station is located,

the at least one base station within the area is a serving base station,

the at least one neighboring base station schedules measurements for mobile stations connected therewith, and

the serving base station is further configured to allocate at least one subcarrier to at most one of said mobile stations within the determined area, wherein each of the at least one neighboring base stations is configured to distribute the subcarrier allocations to all other base stations within the determined area,

wherein:

the serving base station is further configured to transmit the schedule also to the at least one neighboring base station,

the mobile station is further configured to transmit the measurement signals also to the at least one neighboring base station, and

the at least one neighboring base station is configured to calculate a mean channel state for the mobile station and to transmit the mean channel state to at least one further base station of the radio communication system; and

the at least one neighboring base station is configured to distribute transmit power that mobile stations connected therewith use for their measurement allocation to all other base stations within the determined area,

wherein the serving base station coordinates its measurement with the at least one neighboring base station within a certain range,

wherein all base stations within the range schedule measurement for their mobile stations during the same OFDM symbols and do not schedule any other transmissions during that time.

13. A serving base station of a radio communication system comprising a receiver, a transmitter and an antenna system, wherein the serving base station is configured to:

generate a schedule for measurement signals and to transmit the schedule to a mobile station;

receive measurement signals from the mobile station transmitted in accordance with the schedule;

calculate a channel state for an uplink channel from the mobile station to the serving base station; and

determine an area around a sector in which the mobile station is located, wherein base stations within the area are neighboring base stations of the serving base station; and

wherein the serving base station is further configured to:

transmit the schedule also to at least one neighboring base station, and

receive a mean channel state calculated for an uplink channel from the mobile station to at least one neighboring base station in the at least one neighboring base station,

wherein the serving base station coordinates its measurement with the at least one neighboring base station within a certain range,

wherein all base stations within the range schedule measurement for their mobile stations during the same OFDM symbols and do not schedule any other transmissions during that time.

14. A neighboring base station of a radio communication system comprising a receiver, a transmitter and an antenna system, wherein the neighboring base station is configured to:

receive a schedule for measurement signals generated from a serving base station;

receive measurement signals from a mobile station;

calculate a mean channel state for the mobile station; and

transmit the mean channel state to at least one further base station of the radio communication system;

schedule measurements for mobile stations connected therewith;

distribute transmit power that mobile stations connected therewith use for their measurement allocation to all other base stations within a predetermined area intended for measurement of mobile stations connected therewith; and

distribute the subcarrier allocations to all other base stations within the determined area if at least one subcarrier is allocated to at most one of said mobile stations within the determined area,

wherein all base stations within a certain range schedule measurement for their mobile stations during the same OFDM symbols and do not schedule any other transmissions during that time.

15. A mobile station of a radio communication system comprising a receiver, a transmitter and an antenna system, wherein the mobile station is configured to:

receive a schedule for measurement signals from a serving base station wherein the received schedule indicates that the serving base station has coordinated its measurement with at least one neighboring base station within a certain range; and

transmit measurement signals in accordance with the schedule to the serving base station;

wherein the mobile station is further configured to transmit the measurement signals also to the at least one neighboring base station, and wherein all base stations within the range schedule measurement for their mobile stations during the same OFDM symbols and do not schedule any other transmissions during that time.