Method for identification of base stations and for checking measurement values of an observed time difference between transmissions from base stations

• US 20040082344A1
• Filed: 12/02/2003
• Published: 04/29/2004
• Est. Priority Date: 11/05/2001
• Status: Active Grant

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Corporation
• Inventors: Ruutu, Ville, Moilanen, Jani M.
• Granted Patent: US 7,280,831 B2
• Time in Patent Office: Days
• US Class Current: 455/456.3
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method for identification of transceiver devices is disclosed constituting a radio communication network, said method comprising the steps of pre-identifying said transceiver devices, judging that there is an ambiguous result obtained in said pre-identification, and verifying said ambiguous result by identifying said transceiver devices based on real time difference RTD values between said transceiver devices. Also, a method for checking measurement values of an observed time difference OTD obtained at a mobile transceiver device operated within a radio communication network constituted by transceiver devices is disclosed, wherein said checking is based on real time difference RTD values between said transceiver devices. Thus, an improved method is obtained for mobile station location determination and/or for taking handover decisions as well as a way of verifying the reliability of obtained measurement results.

Claims

1. A method for identification of transceiver devices constituting a radio communication network, said method comprising the steps of

pre-identifying said transceiver devices,

judging that there is an ambiguous result obtained in said pre-identification, and

verifying said ambiguous result by identifying said transceiver devices based on real time difference RTD values between said transceiver devices.

2. A method according to claim 1, wherein

said pre-identifying is accomplished based on respective broadcast control channel BCCH information of said transceiver devices.

3. A method according to claim 1 or 2, wherein

said pre-identifying is accomplished based on a respective base station identity code BSIC of said transceiver devices.

4. A method according to claim 1, wherein

it is judged that there is an ambiguous result obtained in said pre-identification, if the transceiver devices can no longer be distinguished from each other.

5. A method according to claim 4, wherein

the transceiver devices can no longer be distinguished from each other if the respective BCCH information of said transceiver devices are identical.

6. A method according to claim 4 or 5, wherein

the transceiver devices can no longer be distinguished from each other, if the respective base station identity code BSIC of said transceiver devices are identical.

7. A method according to claim 1, wherein

said verifying is based on a relation between an observed time difference OTD at a mobile transceiver device,

the real time difference RTD of transmission times between said transceiver devices constituting said radio communication network, and

the geometric time difference GTD being due to different propagation times between the mobile transceiver device and the transceiver devices constituting said radio communication network, the relation being expressed as

OTD=RTD+GTD.

8. A method according to claim 7, wherein

said verifying comprises

estimating a minimum GTD_expected,min and a maximum GTD_expected,max value of said geometric time difference GTD,

deriving, based on said observed time difference OTD and said estimated maximum and minimum geometric time difference GTD, a respective minimum RTD_expected,min and a maximum RTD_expected,max expected value of said real time difference RTD such that

RTD_expected,min=OTD−

GTD_expected,max RTD_expected,max=OTD−

GTD_expected,min

9. A method according to claim 8, wherein

said verifying further comprises

comparing known real time difference RTD values of said transceiver devices with said range of expected real time difference values RTD_expected,min, RTD_expected,max, and

if the real time difference value of the transceiver device is found to be within said range of expected real time difference values, identifying this transceiver device as an unambiguous neighbor transceiver device to a reference transceiver device.

18. A device for identification of transceiver devices constituting a radio communication network, the device being adapted to carry out the method according to any of the preceding claims 1 to 9, or 14 to 17 when dependent on claim 8.

10. A method for checking measurement values of an observed time difference OTD obtained at a mobile transceiver device operated within a radio communication network constituted by transceiver devices, wherein

said checking is based on real time difference RTD values between said transceiver devices.

11. A method according to claim 10, wherein

said checking is based on a relation between

an observed time difference OTD at a mobile transceiver device,

the real time difference RTD of transmission times between said transceiver devices constituting said radio communication network, and

the geometric time difference GTD being due to different propagation times between the mobile transceiver device and the transceiver devices constituting said radio communication network, the relation being expressed as

OTD=RTD+GTD.

12. A method according to claim 11, wherein

said checking comprises

estimating a minimum GTD_expected,min and a maximum GTD_expected,max value of said geometric time difference GTD,

obtaining, based on said real time difference RTD and said estimated maximum and minimum geometric time difference GTD, a respective minimum OTD_expected,min and a maximum OTD_expected,max expected value of said observed time difference OTD such that

OTD_expected,min=RTD+GTD_expected,max OTD_expected,max=RTD+GTD_expected,min

13. A method according to claim 12, wherein

said checking further comprises

comparing measured observed time difference OTD values with said range of expected observed time difference values OTD_expected,min, OTD_expected,max, and

if the observed time difference value at the mobile transceiver device is found to be within said range of expected observed time difference values, this measurement value is accepted, while otherwise it is rejected.

14. A method according to claim 8 or 12, wherein

said estimation of maximum and minimum geometric time difference GTD is based on information about the location of the mobile transceiver device already available in the communication network.

15. A method according to claim 14, wherein

said already available information about the location of the mobile transceiver device is obtained, in GSM communication systems, using Cell Identity CI and/or Cell Identity CI and Timing Advance TA values of the mobile transceiver device, and, in UMTS communication systems, using Cell Identity (CI) and/or Cell Identity CI and Service Area Identifier SAI and/or Round Trip Time (RTT) values.

16. A method according to claims 8 or 12, wherein

said estimation of maximum and minimum geometric time difference GTD_max, GTD_min further comprises

setting the maximum GTD value GTD_max equal to the distance between the two transceiver devices divided by the speed of radio waves, and

setting the minimum GTD value GTD_min equal to the negative of the distance between the two transceiver devices divided by the speed of radio waves.

17. A method according to claims 8 or 12, wherein

said estimation of maximum and minimum geometric time difference GTD_max, GTD_min further comprises

performing the estimation as stated in claim 14 or 15,

performing the estimation as stated in claim 16,

selecting for the maximum GTD_max the value of the estimates obtained in the two steps above which is smaller, and

selecting for the minimum GTD_min the value of the estimates obtained in the two steps above which is larger.

19. A device for checking measurement values of an observed time difference OTD obtained at a mobile transceiver device operated within a radio communication network constituted by transceiver devices, the device being adapted to carry out the method according to any of the preceding claims 10 to 13, or 14 to 17 when dependent on claim 12.