Method and communication system for estimating an error covariance matrix for the downlink in cellular mobile radio telephone networks with adaptive antennas

• US 7,555,266 B2
• Filed: 05/22/2001
• Issued: 06/30/2009
• Est. Priority Date: 05/22/2000
• Status: Expired due to Fees

• Current Assignee: Nokia Siemens Networks GmbH & Company KG (Nokia Corporation)
• Original Assignee: Nokia Siemens Networks GmbH & Company KG (Nokia Corporation)
• Inventors: Haardt, Martin, Mecklenbraeuker, Christoph
• Primary Examiner(s): Yun; Eugene
• Application Number:
  US10/276,922
• Publication Number:
  US 20030162501A1
• Time in Patent Office: 2,961 Days
• Field of Search: 455/63.1, 455/63.4, 455/67.11, 455/67.13, 455/114.2, 455/115.1, 455/115.3, 455/522, 455/13.4, 455/127.1, 455/127.5, 455/422.1
• US Class Current: 455/63.1
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0617 for beam forming

Abstract

Data is transmitted in a radio communication system having two or more base stations that are located in the network and having additional radio stations, which are each connected to one of the base stations via radio interfaces. At least one first base station has an antenna array with a multitude of antenna elements and with a signal processing device for the directional transmitting-receiving of data. The first base station temporally overlays data to a radio station, which is connected to the base station, for the transmission of data from an external base station to an external radio station connected thereto. The transmission of data from the first base station is also received from the external radio station. The objective is to reduce the amount of disturbance to the external radio station caused by transmissions from the base station in the downlink direction. To this end, the transmitting power of the antenna array of the base station is reduced in the direction toward the external radio station after a transmission of a training signal of the transmitted signal for the external radio station and after the reception of an assignable training signal of the external radio station.

Claims

1. A method for data transmission in a radio communication system having at least two base stations and radio stations that are connected in each case to one of the base stations via wireless interfaces, at least a first base station having an antenna arrangement with a plurality of antenna elements and a signal processing device for transmitting and receiving data as a function of direction, comprising:

transmitting data from the first base station to a first radio station communicating therewith in a cell, concurrently with transmission of data from a second base station adjacent to the first base station, to at least one second radio station communicating therewith in an adjacent cell which is adjacent to the cell;

determining, at the first base station, whether downlink transmission of the data from the first base station causes a disturbance for the at least one second radio station in the adjacent cell; and

reducing downlink transmission power of the antenna arrangement of the first base station only in a downlink direction that is directed towards the at least one second radio station in the adjacent cell when it is determined that downlink transmission of the data from the first base station does cause a disturbance for the at least one second radio station in the adjacent cell.

2. The method as claimed in claim 1, further comprising transmitting to the first base station, as the signal information relating to the signal transmitted by the at least one second radio station, at least one training signal of the at least one second radio station.

3. The method as claimed in claim 2, wherein the signal information includes downlink time slots during which the at least one second radio station receives data from the second base station.

4. The method as claimed in claim 2, wherein the signal information includes an uplink time slot of the at least one second radio station.

5. The method as claimed in claim 4, wherein the signal information is transmitted via network devices in the radio communication system.

6. The method as claimed in claim 1, wherein the signal information is transmitted via network devices in the radio communication system.

7. The method as claimed in claim 1, wherein said transmitting of data uses one of an FDD and a TDD mode in at least one of time slots and a multi-slot method.

8. The method as claimed in claim 1, wherein the signal information is transmitted to the first base station one of regularly and after setting up a connection of the second base station to the at least one second radio station.

9. The method as claimed in claim 1, wherein the signal information includes downlink time slots during which the at least one second radio station receives data from the second base station.

10. The method as claimed in claim 1, further comprising taking into account disturbing interference that does not originate from the radio communication system using the spatial error covariance matrix.

11. The method as claimed in claim 1, wherein the radio communication system includes asynchronous switching points, and

wherein said method further comprises transferring the signal information relating to the training signals and the uplink time slots of the second base station to the first base station when the uplink time slots are used by the first base station as downlink time slots.

12. The method for data transmission in a radio communication system of claim 1, further comprising:

compensaling for disturbance via error covariance matrices that follow from the a priori model for two or three-dimensional noise in a direction of the disturbed radio station, which is adjacent to the disturbing first base station.

13. A method for data transmission in a radio communication system having at least two base stations and radio stations that are connected in each case to one of the base stations via wireless interfaces, at least a first base station having an antenna arrangement with a plurality of antenna elements and a signal processing device for transmitting and receiving data as a function of direction, comprising:

transmitting data from the first base station to a first radio station communicating therewith in a cell, concurrently with transmission of data from a second base station adjacent to the first base station, to at least one second radio station communicating therewith in an adjacent cell which is adjacent to the cell;

determining that transmission of the data from the first base station causes a disturbance for the at least one second radio station in the adjacent cell;

reducing transmission power of the antenna arrangement of the first base station directed towards the at least one second radio station in the adjacent cell which is disturbed, after reception of signal information relating to a signal transmitted by the at least one second radio station and reception of a signal assignable to the at least one second radio station;

transmitting to the first base station, as the signal information relating to the signal transmitted by the at least one second radio station, at least one training signal of the at least one second radio station, wherein the signal information includes an uplink time slot of the at least one second radio station, and the signal information is transmitted via network devices in the radio communication system; and

setting a distribution of a spatial transmit power at the first base station based on a spatial error covariance matrix R_I^(I) which yields a beam-shaping vector (w^(k)) as a solution to an optimization problem defined as follows

$r\left(w^{\left(k\right)}\right)=\frac{w^{\left(k\right)<br><br>H}<br><br>R_S^{\left(k\right)}<br><br>w^{\left(k\right)}}{w^{\left(k\right)<br><br>H}<br><br>R_I^{\left(k\right)}<br><br>w^{\left(k\right)}}=\max !,$

and

weighting signals transmitted by the first base station using the beam-shaping vector.

14. The method as claimed in claim 13, further comprising solving the optimization problem by solving a general eigenvalue problem with positive semi-definite Hermitian matrix R_S^(k) and positive definite Hermitian matrix R_I^(k),

R_S^(k)w^(k)=λ

R_I^(k)w^(k)

to obtain the beam-shaping vector w^(k) as an eigenvector relating to a maximum eigenvalue.

15. The method as claimed in claim 14, wherein said transmitting of data uses one of an FDD and a TDD mode in at least one of time slots and a multi-slot method.

16. The method as claimed in claim 15, wherein the signal information is transmitted to the first base station one of regularly and after setting up a connection of the second base station to the at least one second radio station.

17. The method as claimed in claim 16, wherein the signal information includes downlink time slots during which the at least one second radio station receives data from the second base station.

18. The method as claimed in claim 17, further comprising taking into account disturbing interference that does not originate from the radio communication system using the spatial error covariance matrix.

19. The method as claimed in claim 18, wherein the radio communication system includes asynchronous switching points, and

wherein said method further comprises transferring the signal information relating to the training signals and the uplink time slots of the second base station to the first base station when the uplink time slots are used by the first base station as downlink time slots.

20. A method for data transmission in a radio communication system having at least two base stations and radio stations that are connected in each case to one of the base stations via wireless interfaces, at least a first base station having an antenna arrangement with a plurality of antenna elements and a signal processing device for transmitting and receiving data as a function of direction, comprising:

transmitting data from the first base station to a first radio station communicating therewith in a cell, concurrently with transmission of data from a second base station adjacent to the first base station, to at least one second radio station communicating therewith in an adjacent cell which is adjacent to the cell;

determining that transmission of the data from the first base station causes a disturbance for the at least one second radio station in the adjacent cell;

reducing transmission power of the antenna arrangement of the first base station directed towards the at least one second radio station in the adjacent cell which is disturbed, after reception of signal information relating to a signal transmitted by the at least one second radio station and reception of a signal assignable to the at least one second radio station; and

setting a distribution of a spatial transmit power at the first base station based on a spatial error covariance matrix R_I^(I) which yields a beam-shaping vector (w^(k)) as a solution to an optimization problem defined as follows

$r<br><br>\left(w^{\left(k\right)}\right)=\frac{w^{\left(k\right)<br><br>H}<br><br>R_s^{\left(k\right)}<br><br>w^{\left(k\right)}}{w^{\left(k\right)<br><br>H}<br><br>R_I^{\left(k\right)}<br><br>w^{\left(k\right)}}=\max !,$

and

weighting signals transmitted by the first base station using the beam-shaping vector.

21. The method as claimed in claim 20, further comprising solving the optimization problem by solving a general eigenvalue problem with positive semi-definite Hermitian matrix R_S^(k) and positive definite Hermitian matrix R_I^(k),

R_S^(k)w^(k)=λ

R_I^(k)w^(k)

to obtain the beam-shaping vector w^(k) as an eigenvector relating to a maximum eigenvalue.

22. A radio communication system, comprising:

at least first and second base stations;

at least first and second radio stations communicating with the first and second base stations, respectively, via wireless interfaces, the at least first radio station being in a cell and the at least second radio station being in an adjacent cell which is adjacent to the cell; and

at least one antenna arrangement, coupled to the first base station, having a plurality of antenna elements and a signal processing device to transmit and receive data as a function of direction;

including transmitting data from the first base station to the first radio station in the cell concurrently with transmission of data from the second base station to the second radio station in the adjacent cell,

wherein when the first base station determines that downlink transmission of data from the first base station disturbs the second radio station in the adjacent cell, the signal processing device reduces downlink transmission power of the antenna arrangement of the first base station only in a downlink direction towards the second radio station in the adjacent cell after reception of signal information relating to a signal transmitted by the second radio station and reception of a signal assignable to the second radio station.