Estimating subscriber terminal speed, selecting cell, and radio system

• US 6,480,716 B2
• Filed: 11/12/1999
• Issued: 11/12/2002
• Est. Priority Date: 05/13/1997
• Status: Expired due to Fees

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Salonaho, Oscar
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Milord, Marceau
• Application Number:
  US09/440,680
• Publication Number:
  US 20020068581A1
• Time in Patent Office: 1,096 Days
• Field of Search: 455/434, 455/437, 455/441, 455/444, 455/522, 455/456, 455/436, 370/468, 370/337
• US Class Current: 455/441
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 36/04 Reselecting a cell layer in multi-layered cells
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 36/324 by mobility data, e.g. speed data

Abstract

The invention relates to a method for determining a speed of a subscriber terminal and for selecting a cell in a radio system comprising a plural number of microcells and at least one umbrella cell covering the microcells. The method, and a radio system applying the method, comprise means (32 and 33) which use powers of received signals for producing a probability representing an interdependence between at least two powers measured at different points of time. The probability is used for determining the speed of the subscriber terminal in means (34). In addition, on the basis of the speed of the subscriber terminal, either a microcell or an umbrella cell is selected as a cell for the active operation of the subscriber terminal.

Claims

1. A method for estimating a movement of a subscriber terminal in a radio system comprising:

repeatedly measuring and storing at, at least one base station or a subscriber terminal at different points in time, a power of a received signal, the transmission power of the received signal being substantially constant or known,

wherein measured powers of the received signal are used for producing a probability representing an interdependence between powers measured at least at two different points of time, the probability being used for estimating a movement of a subscriber terminal.

4. A method according to claim 1, wherein performing the measurements during a predetermined period of measurement, further comprises, producing from the period of measurement a moving average of the power of a signal, normalizing the values of the measured powers of received signals by the moving average of the power of the signal, and using the normalized powers for producing a probability.

5. The method according to claim 4, wherein a normalization is performed by subtracting the moving average from the measurement results of said measurement period.

6. The method according to claim 1, further comprises dividing a range between a highest and a lowest power into a predetermined number of power classes, to which the measured powers are approximated,

producing at least one probability representing an interdependence between at least two power classes of different points of time, and

estimating, on the basis of said at least one probability, the movement of the subscriber terminal.

7. The method according to claim 1, wherein producing a group of probabilities representing a probability distribution of variation in powers between two successive points of time, and using the probability distribution for estimating the movement of the subscriber terminal.

8. The method according to claim 1, wherein producing at least one probability of a received power remaining substantially unchanged at least at two successive points of time and using said at least one probability for estimating the movement of the subscriber terminal.

9. The method according to claim 8, wherein the smaller the probability, the faster the movement of the subscriber terminal is estimated to be.

10. The method according to claim 1, further comprises producing at least one probability of a received power changing at least at two successive points in time, and using said at least one probability for estimating the movement of the subscriber terminal.

11. The method according to claim 10, wherein the smaller the probability, the slower the movement of the subscriber terminal is estimated to be.

12. The method according to claim 1, wherein the probability estimating the movement is matched to a predetermined statistical model to provide a more accurate estimation of the movement of the subscriber terminal.

13. The method according to claim 1, wherein the estimated movement of the subscriber terminal is used for updating an active group of the subscriber terminal.

14. The method according to claim 1, wherein the subscriber terminal transmits the probability the subscriber terminal has produced to the base station for the movement of the subscriber terminal to be estimated.

15. The method according to claim 1, wherein the base station transmits the probability the base station has produced to the subscriber terminal for the movement of the subscriber terminal to be estimated.

16. The method according to claim 1, wherein the movement of the subscriber terminal is estimated using a neuronetwork.

2. A method for selecting a cell in a radio system comprising a plural number of microcells and at least one umbrella cell covering the microcells;

the radio system comprising;

actively operating at least one base station and a subscriber terminal either in a microcell or in the umbrella cell; and

repeatedly measuring and storing at, at least one base station or subscriber terminal at different points in time, a power of a received signal, the transmission power of the signal being substantially constant or known, wherein using the measured powers of the received signal for producing a probability representing an interdependence between powers measured at least at two different points of time, the probability being used for estimating a movement of a subscriber terminal, and

selecting, on the basis of the estimated movement of the subscriber terminal, either a microcell or an umbrella cell as a cell for the active operation of the subscriber terminal.

3. The method according to claim 2, wherein if the estimated movement of the subscriber terminal is faster than a predetermined threshold value, the cell selected for the active operation of the subscriber terminal is an umbrella cell and if the estimated movement of the subscriber terminal is slower than a predetermined threshold value, the cell selected for the active operation of the subscriber terminal is a microcell.

17. The radio system comprising:

at least one base station and a subscriber terminal, at least one of which is arranged to repeatedly measure and store at different points of time a power of a received signal, the transmission power of the signal being substantially constant or known,

wherein the radio system is arranged to use the measured powers of signals for producing a probability representing an interdependence between powers measured at least at two different points in time, the radio system being arranged to use the probability for estimating a movement of a subscriber terminal.

20. The radio system according to claim 17, wherein the radio system is arranged to perform the measurements at a predetermined period of measurement and to normalize the values of the powers of a received signal by a moving average of a power of the signal.

21. The radio system according to claim 20, wherein the radio system is arranged to normalize the values of the powers by subtracting the moving average from the measurement results of the measurement period.

22. The radio system according to claim 17, wherein the radio system is arranged to divide a range between a highest and a lowest power into a predetermined number of power classes, to which the radio system is arranged to approximate the measured values, and

the radio system is arranged to produce at least one probability representing an interdependence between at least two power classes of different points of time and the radio system is arranged to estimate on the basis of said at least one probability the movement of the subscriber terminal.

23. The radio system according to claim 17, wherein when the produced probabilities represent a probability distribution of variation in the measured powers, the radio system is arranged to estimate the movement of the subscriber terminal between two successive points of time by using the probability distribution.

24. The radio system according to claim 17, wherein the radio system is arranged to produce a probability of a received power remaining substantially unchanged at least at two successive points of time, and to use said probability for estimating the movement of the subscriber terminal.

25. The radio system according to claim 24, wherein the radio system is arranged so that the smaller the probability, the faster the system estimates the movement of the subscriber terminal to be.

26. The radio system according to claim 17, wherein the radio system is arranged to produce at least one probability of a received power changing at least at two successive points of time, and to use said at least one probability for estimating the movement of the subscriber terminal.

27. The radio system according to claim 26, wherein the radio system is arranged so that the smaller the probability, the slower the system estimates the movement of the subscriber terminal to be.

28. The radio system according to claim 17, wherein producing at least one probability of the power of a received signal changing at least at two successive points of time and using said at least one probability for estimating the movement of the subscriber terminal.

29. The radio system according to claim 28, wherein the smaller the probability, the slower the movement of the subscriber terminal is estimated to be.

30. The radio system according to claim 17, wherein the radio system is arranged to match the probability estimating the movement to a predetermined statistical model for a more accurate estimation of the movement of the subscriber terminal.

31. The radio system according to claim 17, wherein on the basis of the estimated movement of the subscriber terminal, the radio system is arranged to update an active group of the subscriber terminal.

32. The radio system according to claim 17, wherein the subscriber terminal is arranged to transmit the probability the subscriber terminal has produced to the base station for the movement of the subscriber terminal to be estimated.

33. The radio system according to claim 17, wherein the base station is arranged to transmit the probability the base station has produced to the subscriber terminal for the movement of the subscriber terminal to be estimated.

34. The radio system according to claim 17, wherein the radio system further comprises a neuronetwork which is used for estimating the movement the subscriber terminal.

18. The radio system comprising:

at least one base station and a subscriber terminal, which is arranged to function actively either in a microcell or an umbrella cell;

at least one base station or subscriber terminal being arranged to repeatedly measure and store at different points of time a power of a received signal, the transmission power of the signal being substantially constant or known,

wherein the radio system is arranged to use the measured powers of signals to produce a probability representing an interdependence between powers measured at least at two different points of time, the probability estimating a movement of a subscriber terminal, and

the radio system is arranged to select, on the basis of the estimated movement of the subscriber terminal, either a microcell or an umbrella cell as a cell for the active operation of the subscriber terminal.

19. The radio system according to claim 18, wherein if the movement of the subscriber terminal is estimated to be faster than the movement indicated by a predetermined threshold value, the radio system is arranged to select an umbrella cell as the cell for the active operation of the subscriber terminal and if the movement of the subscriber terminal is estimated to be slower than the movement indicated by a predetermined threshold value, the radio system is arranged to select a microcell as the cell for the active operation of the subscriber terminal.