Mobile radio communication system

Abstract

A mobile radio communication system of the cellular system wherein a base station and a mobile station are connected to each other. Particularly, a mobile radio communication system wherein transmission power control is performed by a base station constructed such that, at least with regard to a control signal, soft hand-off control wherein a mobile station and base stations are connected simultaneously to each other is performed, but with regard to any other signal other than the control signal, hard hand-off control is performed. By the construction, the communication capacity of the entire system can be increased and the stability can be maintained.

What is claimed is: 
     
       1. A mobile radio communication system, comprising:
 at least two adjacent base stations; 
 a mobile station movable between cells formed by and connectable to the base stations; and 
 means for performing transmission power control whereby, when the mobile station and the base stations are connected to each other, soft hand-off control is performed for a control signal, and hard hand-off control is performed for signals other than the control signal, 
 wherein each of the base stations includes connection number supervision means for counting the number of mobile stations connected to a base station, the connection number supervision means causing soft hand-off control to be performed only for the control signal when the number of connected mobile stations is greater than a predetermined threshold value and to be performed for both the control signal and for the signals other than the control signal when the number of connected mobile stations is equal to or less than the predetermined threshold value. 
 
     
     
       2. The mobile radio communication system according to  claim 1 , wherein each of the base stations transmits as the control signal a transmission power control signal for the mobile station and performs soft hand-off control for the transmission power control signal. 
     
     
       3. The mobile radio communication system according to  claim 1 , wherein each of the base stations includes connection number supervision means for counting the number of mobile stations connected to a base station, the connection number supervision means causing soft hand-off control to be performed only for the control signal when the number of connected mobile stations is greater than a predetermined threshold value and to be performed for both the control signal and for the signals other than the control signal when the number of connected mobile stations is equal to or less than the predetermined threshold value. 
     
     
       4. The A mobile radio communication system according to  claim 1 , comprising:
 at least two adjacent base stations; 
 a mobile station movable between cells formed by and connectable to the base stations; and 
 means for performing transmission power control whereby, when the mobile station and the base stations are connected to each other, soft hand-off control is performed for a control signal, and hard hand-off control is performed for signals other than the control signal, 
 wherein each of the base stations includes quality supervision means for supervising a signal quality to/from the mobile station, the quality supervision means causing soft hand-off control to be performed only for the control signal when the signal quality is greater than a predetermined threshold value and to be performed for both the control signal and for the signals other than the control signal when the signal quality is equal to or less than the predetermined threshold value. 
 
     
     
       5. The mobile radio communication system according to  claim 1 , wherein each of the base stations sets, when hard hand-off control is to be performed for the signals other than the control signal, a control signal level that is higher than the control signal level used when soft hand-off control is performed for the signals other than the control signal. 
     
     
       6. The mobile radio communication system according to  claim 1 , wherein the mobile station and the base stations are connected to each other by a code division multiplex access system. 
     
     
       7. A mobile station for a mobile radio communication system wherein
 the mobile station is movable between cells formed by at least two adjacent base stations; and 
 the mobile station and the base stations are connectable to each other, the mobile station comprising:
 means for performing soft hand-off control for control signals transmitted from the base stations and for performing hard hand-off control for information signals transmitted from the base stations, 
 
 wherein soft hand-off control to be performed only for the control signal when the number of connected mobile stations to a respective base station is greater than a predetermined threshold value and to be performed for both the control signal and for the signals other than the control signal when the number of connected mobile stations is equal to or less than the predetermined threshold value. 
 
     
     
       8. The mobile station according to  claim 7 , wherein the mobile station and the base stations are connected to each other by a code division multiplex access system. 
     
     
       9. The mobile station according to  claim 7 , wherein each of the base stations transmits, as a control signal, a transmission power control signal for controlling the transmission power of the mobile station and performs soft hand-off control for the transmission power control signal. 
     
     
       10. The mobile station according to  claim 7 , wherein the mobile station compares, when control signals are received from the base stations, contents of the control signals and determines an operation to be performed based on a comparison result of. 
     
     
       11. A base station among a plurality of adjacent base stations for a mobile radio communication system wherein the plurality of base stations and a mobile station movable between cells formed by the plurality of base stations are connectable to each other, the base station comprising:
 means for performing soft hand-off control for control signals to be transmitted from the base station and for performing hard hand-off control for information signals to be transmitted from the base station, and 
 connection number supervision means for counting a number of mobile stations connected thereto, and wherein the base station performs soft hand-off control only for a control signal when the number of connected mobile stations is greater than a predetermined threshold value and performs soft hand-off control for both the control signal and signals other than the control signal when the number of connected mobile stations is equal to or less than the predetermined threshold value. 
 
     
     
       12. The base station according to  claim 11 , wherein the base station is adapted so that the mobile station and the plurality of base stations are connected to each other by a code division multiplex access system. 
     
     
       13. The base station according to  claim 11 , wherein the base station transmits, as a control signal, a transmission power control signal for controlling the transmission power of the mobile station and performs soft hand-off control for the transmission power control signal. 
     
     
       14. The base station according to  claim 11 , further comprising connection number supervision means for counting a number of mobile stations connected thereto, and wherein the base station performs soft hand-off control only for a control signal when the number of connected mobile stations is greater than a predetermined threshold value and performs soft hand-off control for both the control signal and signals other than the control signal when the number of connected mobile stations is equal to or less than the predetermined threshold value. 
     
     
       15. The base station according to  claim 11 , further comprising A base station among a plurality of adjacent base stations for a mobile radio communication system wherein the plurality of base stations and a mobile station movable between cells formed by the plurality of base stations are connectable to each other, the base station comprising:
 means for performing soft hand-off control for control signals to be transmitted from the base station and for performing hard hand-off control for information signals to be transmitted from the base station, and 
 quality supervision means for supervising a signal quality to/from the mobile station, whereby soft hand-off control is performed only for a control signal when the signal quality is higher than a predetermined threshold value and is performed for both the control signal and signals other than the control signal when the signal quality is equal to or less than the predetermined threshold value. 
 
     
     
       16. The base station according to  claim 11 , wherein the base station sets, when hard hand-off control is to be performed for signals other than a control signal, a control signal level higher than the control signal level used when soft hand-off control is performed for signals other than the control signal. 
     
     
       17. The mobile radio communication system according to claim 4, wherein each of the base stations transmits as the control signal a transmission power control signal for the mobile station and performs soft hand-off control for the transmission power control signal. 
     
     
       18. The mobile radio communication system according to claim 4, wherein each of the base stations sets, when hard hand-off control is to be performed for the signals other than the control signal, a control signal level that is higher than the control signal level used when soft hand-off control is performed for the signals other than the control signal. 
     
     
       19. The mobile radio communication system according to claim 4, wherein the mobile station and the base stations are connected to each other by a code division multiplex access system. 
     
     
       20. A mobile station for a mobile radio communication system wherein
 the mobile station is movable between cells formed by at least two adjacent base stations; and   the mobile station and the base stations are connectable to each other, the mobile station comprising:   means for performing soft hand-off control for control signals transmitted from the base stations and for performing hard hand-off control for information signals transmitted from the base stations,   wherein soft hand-off control to be performed only for the control signal when a signal quality is greater than a predetermined threshold value and to be performed for both the control signal and for the signals other than the control signal when the signal quality is equal to or less than the predetermined threshold value.   
     
     
       21. The mobile station according to claim 20, wherein the mobile station and the base stations are connected to each other by a code division multiplex access system. 
     
     
       22. The mobile station according to claim 20, wherein each of the base stations transmits, as a control signal, a transmission power control signal for controlling the transmission power of the mobile station and performs soft hand-off control for the transmission power control signal. 
     
     
       23. The mobile station according to claim 20, wherein the mobile station compares, when control signals are received from the base stations, contents of the control signals and determines an operation to be performed based on a comparison result of. 
     
     
       24. The base station according to claim 15, wherein the base station is adapted so that the mobile station and the plurality of base stations are connected to each other by a code division multiplex access system. 
     
     
       25. The base station according to claim 15, wherein the base station transmits, as a control signal, a transmission power control signal for controlling the transmission power of the mobile station and performs soft hand-off control for the transmission power control signal. 
     
     
       26. The base station according to claim 15, wherein the base station sets, when hard hand-off control is to be performed for signals other than a control signal, a control signal level higher than the control signal level used when soft hand-off control is performed for signals other than the control signal.