Method for determining a candidate cell for an active set

Abstract

A method ( 200, 300, 400 ) according to the invention is a method for determining a condidate cell for an active set, where the quality factor of each cell in the active set is determined ( 202 ), a quality factor of a test cell is determined ( 203 ), and the test cell is accepted ( 205 ) as a candidate cell for the active set if an acceptance criterion is fulfilled. The method is characterized in that the acceptance criterion is selected ( 201 ) so that for a certain first quality factor of a test cell and for a certain first set of quality factors, consisting of quality factors of the cells in a first active set, the acceptance criterion has the same value as for a certain second quality factor of a test cell and for a certain second set of quality factors, consisting of quality factors of cells in a second active set, when the first quality factor is equal to the second quality factor multiplied with any finite number and the first set of quality factors is the same as a set formed of the quality factors belonging to the second set of quality factors multiplied with the same finite number. The invention relates also to an arrangement, to a mobile station and to a network element where decisions about accepting a cell as a candidate cell for the active set are done.

1. A method for determining a candidate cell for one of a first active set and a second active set, the method  comprising:
 determining a quality factor for each cell in an active set for which the  a candidate cell is to be determined, wherein the active set comprises a first active set or a second active set;  
 determining the quality factor of a test cell;  
 accepting the test cell as a candidate cell for the active set for which the candidate cell is to be determined, if an acceptance criterion, which defines a value as a limit for accepting the test cell, is fulfilled;  
 selecting the acceptance criterion so that within the acceptance criterion a first limit value is equal to a second limit value multiplied by a finite number;  
 wherein said first limit value is for a certain first quality factor of the test cell and for a certain first set of quality factors, consisting of quality factors of cells in the first active set, said second limit value is for a certain second quality factor of the test cell and for a certain second set of quality factors, consisting of quality factors of cells in the second active set, and the first quality factor is equal to the second quality factor multiplied with the finite number and the first set of quality factors is identical to a set formed of the quality factors belonging to the second set of quality factors multiplied by the finite number.  
 
     
     
       2. The method of  claim 1 , wherein said acceptance criterion involves a function, whose value depends at least on quality factors of first cells in the active set for which the candidate cell is to be determined and on certain parameter values, and wherein said acceptance criterion produces the first limit value for said first quality factor of the test cell, said first set of quality factors and first parameter values, which first limit value is equal to a second limit value multiplied by the finite number, said second limit value being for said second quality factor of the test cell, said second set of quality factors and said first parameter values, said first parameter values being any parameter values. 
     
     
       3. The method of  claim 1 , wherein the quality factor of the test cell and the quality factors of the cells in the active set for which the candidate cell is to be determined are normalized with a number having a predefined relative value compared to values of the quality factors of the cells in the active set for which the candidate cell is to be determined, the value for the limit is determined using normalized quality factors of the cells in the active set for which the candidate cell is to be determined and the normalized quality factor of the test cell and the test cell is accepted as a candidate cell, if the acceptance criterion is fulfilled. 
     
     
       4. The method of  claim 3 , wherein the quality factors are normalized using a largest quality factor of the quality factors of the cells in the active set for which the candidate cell is to be determined. 
     
     
       5. The method of  claim 3 , wherein the quality factors are normalized using a smallest quality factor of the quality factors of the cells in the active set for which the candidate cell is to be determined. 
     
     
       6. The method of  claim 3 , wherein the quality factors are normalized using an average quality factor of the quality factors of the cells in the active set for which the candidate cell is to be determined. 
     
     
       7. The method of  claim 1 , wherein the acceptance criterion is such that for the active set for which the candidate cell is to be determined and where all the cells have a certain quality factor, the limit is that certain quality factor. 
     
     
       8. The method of  claim 1 , wherein the method is executed periodically. 
     
     
       9. The method of  claim 1 , wherein the method is triggered by a certain event. 
     
     
       10. The method of  claim 1 , wherein the candidate cell is added to the active set for which the candidate cell is to be determined. 
     
     
       11. The method of  claim 1 , wherein the cell having a worst quality factor in the active set for which the candidate cell is to be determined is replaced with the candidate cell. 
     
     
       12. A method for determining a cell to be removed from one of a first active set and a second active set,  comprising:
 determining a quality factor for each cell in an active set from which the cell is to be removed, wherein the active set comprises a first active set or a second active set;  
 evaluating a rejection criterion using the cell having a smallest quality factor as a test cell and a temporary set, which contains cells of the active set from which the cell is to be removed except the cell having the smallest quality factor;  
 removing the test cell from the active set from which the cell is to be removed, if a rejection criterion, which defines a value as a limit for rejecting the test cell, is fulfilled; and  
 selecting the rejection criterion so that within the rejection criterion a first limit value is equal to a second limit value multiplied by a finite number;  
 wherein said first limit value is for a certain first quality factor of a test cell and for a certain first set of quality factors, consisting of quality factors of cells in a first temporary set, which contains the cells of the first active set except the cell of the first active set having the smallest quantity factor, and the second limit value is for a certain second quality factor of a test cell and for a certain second set of quality factors, consisting of quality factors of cells in a second temporary set, which contains the cells of the second active set except the cell of the second active set having the smallest quantity factor, and the first quality factor is equal to the second quality factor multiplied by the finite number and the first set of quality factors is identical to a set formed of the quality factors belonging to the second set of quality factors multiplied by the finite number.  
 
     
     
       13. The method of  claim 12 , wherein said rejection criterion involves a function, whose value depends at least on quality factors of first cells in the temporary set and on certain parameter values, and wherein said rejection criterion produces the first limit value for said first quality factor of the test cell, said first set of quality factors and first parameter values, which first limit value is equal to the second limit value multiplied by the same finite number, the second limit value being for said second quality factor of the test cell, said second set of quality factors and said first parameter values, said first parameter values being any parameter values. 
     
     
       14. An arrangement for determining a candidate cell for one of a first active set and a second active set, comprising:
 means for determining a quality factor for a test cell;    means for determining quality factors for cells in the active set for which the candidate cell is to be determined;    means for selecting an acceptance criterion, which defines a value as a limit for accepting the test cell and in which a first limit value is equal to a second limit value multiplied by a finite number, said first limit value being for a certain first quality factor of the test cell and for a certain first set of quality factors, consisting of quality factors of cells in the first active set, the second limit value being for a certain second quality factor of the test cell and for a certain second set of quality factors, consisting of quality factors of cells in the second active set, and the first quality factor being equal to the second quality factor multiplied by the same finite number and the first set of quality factors being identical to a set formed of the quality factors belonging to the second set of quality factors multiplied by the finite number; and    means for deciding about the acceptance of the test cell as a candidate cell for the active set for which the candidate cell is to be determined using the acceptance criterion.    
     
     
       15. The arrangement of  claim 14 , wherein said acceptance criterion involves a function, whose value depends at least on quality factors of first cells in the active set for which the candidate cell is to be determined and on certain parameter values, and wherein said acceptance criterion produces a first limit value for said first quality factor of the test cell, said first set of quality factors and first parameter values, which first limit value is equal to the second limit value multiplied by the finite number, the second limit value being for said second quality factor of the test cell, said second set of quality factors and said first parameter values, said first parameter values being any parameter values. 
     
     
       16. A mobile station  An apparatus, comprising:
 means for determining a quality factor for a test cell; 
 means ( 502 ) for determining quality factors for cells in one of a first active set and a second active set; 
 means for selecting  determining an acceptance criterion, which defines a certain value as  for the acceptance criterion so that the certain value for a first limit value for accepting the  a test cell and in which a first limit value  is equal to a second limit value multiplied by  with a finite number, wherein said first limit value being  is for a certain  first quality factor of the test cell and for a certain  first set of quality factors, consisting of quality factors of cells in the  a first active set, the second limit value being  is for a certain  second quality factor of the test cell and for a certain  second set of quality factors, consisting of quality factors of cells in the  a second active set, and the first quality factor being  is equal to the second quality factor multiplied by  with the same  finite number and the first set of the quality factors being identical to  is the same as a set formed of a  quality factors belonging to the second set of the quality factors multiplied by  with the finite number; and  
 means for deciding about the  an acceptance of the test cell as a candidate cell for the  an active set for which the candidate cell is to be determined  using the acceptance criterion.  
 
     
     
       17. The mobile station  apparatus of  claim 16 , wherein said acceptance criterion involves a function, whose value depends at least on quality factors of first cells in the active set for which the candidate cell is to be determined and on certain parameter values, and wherein said acceptance criterion produces the first limit value for said first quality factor of the test cell, said first set of quality factors and first parameter values, which first limit value is equal to the second limit value multiplied by the finite number, the second limit value being for said second quality factor of the test cell, said second set of quality factors and said first parameter values, said first parameter values being any parameter values. 
     
     
       18. The mobile station  apparatus of  claim 16 , wherein said mobile station  apparatus is a mobile station of an Universal Mobile Communication System  a universal mobile communication system. 
     
     
       19. A network element, comprising:
 means for determining a quality factor for a test cell;    means ( 502 ) for determining quality factors for cells in one of a first active set and a second active set;    means for selecting an acceptance criterion, which defines a value as a limit for accepting the test cell and in which a first limit value is equal to a second limit value multiplied by a finite number, said first limit value being for a certain first quality factor of the test cell and for a certain first set of quality factors, consisting of quality factors of cells in the first active set, said second limit value being for a certain second quality factor of the test cell and for certain second set of quality factors, consisting of quality factors of cells in the second active set, and the first quality factor is equal to the second quality factor multiplied by the finite number and the first set of quality factors being identical to a set formed of the quality factors belonging to the second set of quality factors multiplied by the finite number; and    means for deciding about the acceptance of the test cell as a candidate cell for the active set for which the candidate cell is to be determined using the acceptance criterion.    
     
     
       20. The network element  apparatus of claim  19    16 , wherein the network element  apparatus is a network element of a radio access network of an Universal Mobile Communication System  a universal mobile communication system. 
     
     
       21. The network element  apparatus of  claim 20 , wherein the network element is a Radio Network Controller  radio network controller. 
     
     
       22. The network element of  claim 19 , wherein said acceptance criterion involves a function, whose value depends at least on quality factors of first cells in the active set for which the candidate cell is to be determined and on certain parameter values, and wherein said acceptance criterion produces the first limit value for said first quality factor of the test cell, said first set of quality factors and first parameter values, which first limit value is equal to the second limit value multiplied by the finite number, the second limit value being for said second quality factor of the test cell, said second set of quality factors and said first parameter values, said first parameter values being any parameter values. 
     
     
       23. An apparatus, comprising:
 a test cell block configured to determine a quality factor for a test cell; 
 an active cell block configured to determine quality factors for cells in one of a first active set and a second active set; 
 an acceptance criterion block configured to select  determine an acceptance criterion, which defines a certain value as  for the acceptance criterion so that the certain value for a first limit value for accepting the  a test cell and in which a first limit value  is equal to a second limit value multiplied by  with a finite number, wherein said first limit value being  is for a certain  first quality factor of the test cell and for a certain  first set of quality factors, consisting of quality factors of cells in the  a first active set, said  the second limit value being  is for a certain  second quality factor of the test cell and for a certain  second set of quality factors, consisting of quality factors of cells in the  a second active set, and the first quality factor being  is equal to the second quality factor multiplied by  with the finite number and the first set of the quality factors being identical to  is the same as a set formed of the  quality factors belonging to the second set of the quality factors multiplied by  with the finite number; and  
 a decision block configured to decide whether to accept  about an acceptance of the test cell as a candidate cell for the  an active set for which the candidate cell is to be determined  using the acceptance criterion.  
 
     
     
       24. A method, comprising:
 determining a quality factor for each cell in one of a first active set and a second active set;  
 determining a quality factor of a test cell; and  
 accepting the test cell as a candidate cell for an active set for which the candidate cell is to be determined, if an acceptance criterion, which defines a value as a limit for accepting the test cell, is fulfilled;  
 wherein the acceptance criterion is selected so that within the acceptance criterion a first limit value is equal to a second limit value multiplied by a finite number, said first limit value being for a certain first quality factor of the test cell and for a certain first set of quality factors, consisting of quality factors of cells in the first active set, said second limit value being for a certain second quality-factor of a test cell and for a certain second set of quality factors, consisting of quality factors of cells in the second active set, and said first quality factor being equal to the second quality factor multiplied by the finite number and the first set of quality factors being identical to a set formed of the quality factors belonging to the second set of quality factors multiplied by the finite number.  
 
     
     
       25. The apparatus of  claim 16 , wherein said apparatus further comprises:
   means for determining a quality factor for the test cell; and        means for determining quality factors for cells in the active set.     
     
     
       26. The apparatus of  claim 23 , wherein said apparatus further comprises:
   a test cell block configured to determine a quality factor for the test cell; and        an active cell block configured to determine quality factors for cells in the active set.     
     
     
       27. The apparatus of  claim 26 , wherein the quality factor of the test cell and the quality factors of the cells in the active set for which the candidate cell is to be determined are normalized with a number having a predefined relative value compared to values of the quality factors of the cells in the active set for which the candidate cell is to be determined, the value for the limit is determined using normalized quality factors of the cells in the active set for which the candidate cell is to be determined and the normalized quality factor of the test cell and the test cell is accepted as a candidate cell, if the acceptance criterion is fulfilled. 
     
     
       28. The apparatus of  claim 27 , wherein the quality factors are normalized using a largest quality factor of the quality factors of the cells in the active set for which the candidate cell is to be determined. 
     
     
       29. The apparatus of  claim 23 , wherein said acceptance criterion involves a function, whose value depends at least on quality factors of first cells in the active set for which the candidate cell is to be determined and on certain parameter values, and wherein said acceptance criterion produces the first limit value for said first quality factor of the test cell, said first set of quality factors and first parameter values, which first limit value is equal to the second limit value multiplied by the finite number, the second limit value being for said second quality factor of the test cell, said second set of quality factors and said first parameter values, said first parameter values being any parameter values. 
     
     
       30. The apparatus of  claim 23 , wherein said apparatus is a mobile station of a universal mobile communication system. 
     
     
       31. The apparatus of  claim 23 , wherein the apparatus is a network element of a radio access network of an universal mobile communication system. 
     
     
       32. The apparatus of  claim 31 , wherein the network element is a radio network controller.