Method and arrangement in a wireless communication system

• US 9,088,901 B2
• Filed: 02/11/2010
• Issued: 07/21/2015
• Est. Priority Date: 02/11/2010
• Status: Expired due to Fees

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hu, Yang, Gan, Jiansong, Hafeez, Abdulrauf
• Primary Examiner(s): Lai, Andrew
• Assistant Examiner(s): Qin, Zhiren
• Application Number:
  US13/521,600
• Publication Number:
  US 20130194942A1
• Time in Patent Office: 1,986 Days
• Field of Search: 370/252, 370/241, 370/310
• US Class Current: 1/1
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination

Abstract

Method and arrangement in a first base station for calculating a first location parameter α of a user equipment in order to improve beamforming accuracy. The first base station and the user equipment are comprised in a Coordinated Multiple Point “CoMP” communication system together with a second base station. The method comprises measuring a signal received from the user equipment, estimating a first parameter value α′ based on the measured signal, obtaining a second parameter value α″, based on an estimated second location parameter β of the user equipment, estimated at the second base station and calculating the first location parameter α, based on the first estimated parameter value α′ and the obtained second parameter value α″.

Claims

1. A method in a first base station for calculating a first location parameter (α

) of a user equipment in order to improve beamforming accuracy within a Coordinated Multiple Point (CoMP) communication system, which communication system comprises the first base station, the user equipment and a second base station, the method comprising;

measuring a signal received from the user equipment;

determining a first estimate (α

′

) of the first location parameter, based on the measured signal;

obtaining a second estimate (α

″

) of the first location parameter, based on a second location parameter of the user equipment, estimated at the second base station, said second location parameter is different from said second estimate of the first location parameter;

calculating the first location parameter based on the first estimate of the first location parameter and the obtained second estimate of the first location parameter.

2. The method of claim 1 further comprising:

determining a first weight coefficient (a), associated with the first base station, based on the measured first signal from the user equipment;

obtaining a second weight coefficient (b), associated with the second base station; and

wherein the calculating the first location parameter comprises;

multiplying the first weight coefficient with the first estimate of the first location parameter;

multiplying the second weight coefficient with the second estimate of the first location parameter;

adding the two multiplication results such that;

α

=a·

α

′

+b·

α

″

.

3. The method of claim 2 wherein the determining the first weight coefficient is performed based on at least one of the following parameters of the measured first signal:

received signal to noise ratio of uplink sounding reference signals;

uplink timing advance;

estimation of path loss.

4. The method of claim 3 wherein:

a sum of the first weight coefficient and the second weight coefficient is 1;

the relation between the first and second weight coefficients is such that at least one of a higher received signal to noise ratio, shorter uplink timing advance, and lower path loss renders a higher coefficient value and a lower received signal to noise ratio, longer uplink timing advance, or higher path loss render a lower coefficient value.

5. The method of claim 2 wherein the first location parameter is any of:

a direction of arrival of a signal received from the user equipment;

a distance between the first base station and the user equipment.

6. The method of claim 2 wherein the obtaining a second estimate of the first location parameter comprises receiving the second estimate of the first location parameter value from the second base station.

7. The method according to claim 2 wherein the obtaining a second estimate of the first location parameter comprises:

receiving, from the second base station, the second location parameter estimated at the second base station;

calculating the second estimate of the first location parameter based on the received estimated second location parameter and known geometric relation between the first and second base stations.

8. The method of claim 1 wherein the first location parameter is any of:

a direction of arrival of a signal received from the user equipment;

a distance between the first base station and the user equipment.

9. The method of claim 1 wherein obtaining the second estimate of the first location parameter comprises receiving the second estimate of the first location parameter from the second base station.

10. The method according to claim 1 wherein obtaining the second estimate of the first location parameter comprises:

receiving, from the second base station, the second location parameter estimated at the second base station;

calculating the second estimate of the first location parameter value based on the received estimated second location parameter and known geometric relation between the first and second base stations.

11. A base station adapted to calculate a first location parameter (α

) of a user equipment in order to improve beamforming accuracy within a Coordinated Multiple Point (CoMP) communication system, the base station comprising;

a transmitter;

a receiver;

a received signal processor for processing signals received by the receiver, the received signal processor comprising;

a measurement unit configured to perform measurements on a signal received from the user equipment;

an estimating unit configured to estimate a first estimate (α

′

) of the first location parameter based on the measured signal;

a first obtaining unit configured to obtain a second estimate (α

″

) of the first location parameter based on a second location parameter of the user equipment estimated at the second base station, said second location parameter is different from said second estimate of the first location parameter;

a calculating unit configured to calculate the first location parameter based on the first estimate of the first location parameter and the obtained second estimate of the first location parameter.

12. The base station of claim 11 wherein the first obtaining unit is configured to obtain the second estimate of the first location parameter by:

receiving, from the second base station, the estimated second location parameter estimated at the second base station;

calculating the second estimate of the first location parameter based on the received estimated second location parameter and known geometric relation between the first and second base stations.

13. The base station of claim 11 wherein the first location parameter is any of:

a direction of arrival of a signal received from the user equipment;

a distance between the first base station and the user equipment.

14. The base station of claim 11 wherein the received signal processor further comprises:

a determination unit configured to determine a first weight coefficient (a), associated with the first base station, based on the measured signal from the user equipment;

a second obtaining unit configured to obtain a second weight coefficient (b), associated with the second base station;

wherein the calculating unit is configured to calculate the first location parameter by;

multiplying the first weight coefficient with the first estimate of the first location parameter;

multiplying the second weight coefficient with the obtained second estimate of the first location parameter value;

adding the two multiplication results such that;

α

=a·

α

′

+b·

α

″

.

15. The base station of claim 14 wherein the determination unit determines the first weight coefficient based on at least one of the following parameters of the measured signal:

received signal to noise ratio of uplink sounding reference signals;

uplink timing advance;

estimation of path loss.

16. The base station of claim 15 wherein:

a sum of the first weight coefficient and the second weight coefficient is 1;

the relation between the first and second weight coefficients is such that at least one of a higher received signal to noise ratio, shorter uplink timing advance, and lower path loss renders a higher coefficient value and a lower received signal to noise ratio, longer uplink timing advance, or higher path loss renders a lower coefficient value.