BASE STATION SYNCHRONISATION

• US 20120258752A1
• Filed: 12/23/2009
• Published: 10/11/2012
• Est. Priority Date: 12/23/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Liao, Jingyi
• Granted Patent: US 9,031,593 B2
• Time in Patent Office: Days
• US Class Current: 455/509
• CPC Class Codes: H04B 7/2684 Synchronisation of a mobile station with more than one base station
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 56/0055 determining timing error of reception due to propagation delay

Abstract

A method for determining data enabling a plurality of secondary base stations to time their transmissions to a mobile station within a timing range. The mobile station obtains time delays of transmissions from each of the secondary base stations in reaching the mobile station, and determines time delay differences between the time delays and a reference time delay associated with a primary base station. The mobile station transmits the time delay differences to the plurality of secondary base stations. Each secondary base station receives the difference between its own transmission time delay and the reference time delay, compares the difference with a time range, and corrects the timing of its transmissions if the difference is outside of the time range.

Claims

1. A method for determining data enabling a plurality of base stations to time their transmissions to a mobile station within a timing range, the method comprising the steps of:

obtaining, in the mobile station, time delays of transmissions from each of the plurality of base stations in reaching the mobile station;

determining, in the mobile station, time delay differences between the time delays and a reference time delay; and

transmitting the time delay differences from the mobile station to the plurality of base stations via at least one link that is specific to the mobile station in order to enable the timing of transmissions by the base stations to be corrected.

2. The method according to claim 1, wherein the plurality of base stations includes a primary base station and one or more secondary base stations, where the reference time delay is associated with the primary base station transmission and the time delays comprise time delays of the secondary base station transmissions.

3. The method according to claim 1, wherein said at least one link comprises a signaling channel.

4. The method according to claim 2, wherein the mobile station transmits a reference signal, and the method further comprises the steps of:

determining an adjustment factor corresponding to each determined time delay difference; and

applying the adjustment factor on the reference signal intended for each of the secondary base stations.

5. The method according to claim 4, further comprising the step of alternately transmitting a reference signal for at least one secondary base station with and without the adjustment factor.

6. The method according to claim 4, wherein the adjustment factor includes a time adjustment factor shifting the timing of the transmission of the reference signal to one of the secondary base stations with the corresponding time adjustment factor.

7. The method according claim 2, wherein the reference signal includes a constant amplitude zero autocorrelation sequence, the adjustment factor comprises an angular adjustment factor corresponding to the determined time delay difference, and the step of applying the adjustment factor comprises shifting the reference signal for at least one secondary base station with an angle comprising the corresponding angular adjustment factor.

8. A mobile station for determining data allowing a plurality of base stations to time their transmissions to the mobile station within a timing range, the mobile station comprising:

at least one radio communication unit for communicating with the plurality of base stations; and

a control unit configured to;

obtain time delays of transmissions from each of the plurality of base stations in reaching the mobile station;

determine time delay differences between the time delays and a reference time delay; and

control the radio communication unit to transmit the time delay differences from the mobile station to the plurality of base stations via at least one link that is specific to the mobile station in order to enable the timing of transmissions by the base stations to be corrected.

9. (canceled)

10. A method for controlling timing of transmissions to a mobile station from a base station, the method comprising the steps of:

receiving, in a device for controlling the timing and from the mobile station via at least one link that is specific to the mobile station, a difference between a time delay of the transmissions of the base station to the mobile station and a reference time delay;

comparing, in said device, the time delay difference with a time range within which the base station is to time its transmissions to the mobile station; and

correcting, by said device, the timing of the base station transmissions to the mobile station if the difference is outside of the time range.

11. The method according to claim 10, wherein said at least one link comprises a signaling channel.

12. The method according to claim 10, wherein the base station receives a reference signal transmitted by the mobile station, and the method further comprises the steps of:

estimating an adjustment factor that has been applied on the reference signal; and

determining the time delay difference based on the estimated adjustment factor.

13. The method according to claim 12, wherein the reference signal is alternately transmitted by the mobile station with and without the adjustment factor, and the step of estimating the adjustment factor comprises investigating the difference between the reference signal with and without the adjustment factor applied.

14. The method according to claim 12, wherein the adjustment factor includes a time adjustment factor corresponding to the timing difference and that shifts the timing of the transmission of the reference signal with the time adjustment factor, and the step of estimating comprises estimating the time adjustment factor through investigating the shifting of the timing.

15. The method according to claim 12, wherein the reference signal includes a constant amplitude zero autocorrelation sequence that has been shifted with an angle comprising an angular adjustment factor corresponding to the determined time delay difference, and the step of estimating the adjustment factor comprises estimating the angular adjustment factor through investigating the angle of the shift.

16. A device for controlling timing of transmissions to a mobile station from a base station, the device comprising:

a control unit configured to;

receive, from the mobile station via at least one link that is specific to the mobile station, a difference between a time delay of the transmissions of the base station to the mobile station and a reference time delay;

compare the time delay difference with a time range within which the base station is to time its transmissions to the mobile station; and

correct the timing of the base station transmissions to the mobile station if the difference is outside of the time range.

17. The device according to claim 16, wherein the device is implemented in the base station.

19. The device according to claim 16, wherein the device receives a reference signal transmitted by the mobile station, and the control unit is configured to estimate an adjustment factor that has been applied on the reference signal, and to determine the time delay difference based on the estimated adjustment factor.

18. (canceled)