Method for signal acquisition in a wireless terminal and wireless terminal

• US 20030091009A1
• Filed: 11/13/2002
• Published: 05/15/2003
• Est. Priority Date: 11/13/2001
• Status: Active Grant

• Current Assignee: HMD Global Oy
• Original Assignee: Nokia Corporation
• Inventors: Halivaara, Ismo
• Granted Patent: US 7,295,535 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 7/2684 Synchronisation of a mobile station with more than one base station
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 56/00 Synchronisation arrangements

Abstract

The invention relates to a method for acquisition of a signal in a wireless terminal receiving a modulated signal transmitted by at least one base station. In the wireless terminal, timing information of the signal from at least two different base stations is used for the acquisition of the signal of at least one of said base stations. The invention also relates to a system, in which the method is applied, as well as to a wireless terminal.

Claims

1. A method for performing acquisition of a signal in a wireless terminal receiving a modulated signal transmitted by at least one base station, wherein in the wireless terminal, timing data of signals from at least two base stations are used for performing acquisition of the signal of at least one of said base stations.

2. The method according to claim 1, wherein in the acquisition of the signal of the base station, a correlation is made between the signal of the base station and a reference code corresponding to the code used in the modulation of the signal, wherein for the acquisition, the code phase of the reference signal is adjusted, and that said timing information is used in the adjustment of the code phase.

3. The method according to claim 1, wherein said timing information from at least first and second different base stations comprises at least one of the following:

the relative time difference between the signals transmitted by said at least two base stations at the time of transmission,

information about the signal propagation time between the base station and the wireless terminal,

information about the positions of said at least two base stations.

4. The method according to claim 1, wherein acquisition of the signals from at least three different base stations is performed, and that code phases determined during the acquisition of the signals from said at least three different base stations are used in the positioning of the wireless terminal.

5. The method according to claim 2, wherein for the distance of the base stations, the maximum distance is selected as the default value, and that said maximum distance is used in the adjustment of the code phase of said reference signal.

6. The method according to claim 1, wherein as said first base station, the base station serving the wireless terminal at the time is used, wherein the wireless terminal receives the signal of the serving base station, and that information related to the neighbouring base stations of said serving base station is transmitted to the wireless terminal.

7. The method according to claim 6, wherein information is transmitted to the wireless terminal about at least one neighbouring base station of at least one neighbouring base station of said serving base station, which is not a neighbouring base station of said serving base station.

8. The method according to claim 1, wherein the signal transmitted by the base stations is a spread spectrum modulated signal.

9. The method according to claim 1, wherein the base stations are base stations of the UMTS mobile communication system, and that acquisition of the signal of the pilot channel is performed.

10. The method according to claim 2, wherein for the acquisition, at least the following steps are taken in the wireless terminal:

acquisition of the signal of the first base station,

using said timing information about at least two base stations to determine the transmission time difference between said first base station and a second base station,

determining an estimate for the signal propagation time difference between said at least first base station and the wireless terminal and between said second base station and the wireless terminal,

adjusting the code phase of the reference code on the basis of said transmission time difference and said propagation time difference, and

performing a correlation between the received signal and the reference code for acquisition of the signal of the second base station.

11. A system comprising base stations and a wireless terminal with means for receiving a modulated signal transmitted by at least one base station and means for acquisition of the signal transmitted by the base station, wherein the system comprises at least means for using the timing information of the signals from at least two base stations, for acquisition of the signal of at least one of said base stations.

12. The system according to claim 11 comprising means for making a correlation between the signal of the base station and the reference code corresponding to the code used in the modulation of the signal, means for adjusting the code phase of the reference signal, and means for using said timing information in the adjustment of the code phase.

13. The system according to claim 11, wherein said timing information from at least two different base stations comprises at least one of the following:

the relative time difference between the signals transmitted by said at least two base stations at the time of transmission,

information about the signal propagation time between the base station and the wireless terminal,

information about the positions of said at least two base stations.

14. The system according to claim 11, wherein acquisition of the signals from at least three, different base stationsis arranged to be performed, and that code phases determined during the acquisition of the signals from said at least three different base stations are arranged to be used in the positioning of the wireless terminal.

15. The system according to claim 11, wherein the wireless terminal comprises means for receiving the signal of a serving base station, and that the system comprises means for transmitting information related to the neighbouring base stationsof said serving base station to the wireless terminal.

16. The system according to claim 11, wherein the base stations are base stations of the UMTS mobile communication system, and that acquisition of the signal of a pilot channel is arranged to be performed.

17. A wireless terminal comprising means for receiving a modulated signal transmitted by at least one base station and means for acquisition of the signal transmitted by the base station, wherein the wireless terminal comprises means for using the timing information of the signals from at least two base stations, for acquisition of the signal of at least one of said base stations.

18. The wireless terminal according to claim 17 comprising means for making a correlation between the signal of the base station and the reference code corresponding to the code used in the modulation of the signal, means for adjusting the code phase of the reference signal, and means for using said timing information in the adjustment of the code phase.

19. The wireless terminal according to claim 17, wherein said timing information from at least two different base stations comprises at least one of the following:

the relative time difference between the signals transmitted by said at least two base stations at the time of transmission,

information about the signal propagation time between the base station and the wireless terminal,

information about the positions of said at least two base stations.

20. The wireless terminal according to claim 17, wherein it comprises means for acquisition of the signal transmitted from at least three different base stations, and means for using code phases determined during the acquisition of the signal from said at least three different base stations in the positioning of the wireless terminal.

21. The wireless terminal according to claim 17, wherein it comprises a UMTS mobile communication device.