Mobile communication system for predicting a transfer location of a mobile station

• US 6,311,065 B1
• Filed: 02/12/1998
• Issued: 10/30/2001
• Est. Priority Date: 02/12/1997
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Fukazawa, Mitsunori, Ushiki, Kazumasa
• Primary Examiner(s): Chang, Vivian
• Assistant Examiner(s): RAMOS FELICIANO, ELISEO
• Application Number:
  US09/022,715
• Time in Patent Office: 1,356 Days
• Field of Search: 455/436, 455/437, 455/438, 455/441, 455/439, 455/444, 455/456, 455/450, 455/67.1, 455/515, 455/440, 455/433, 342/457, 342/357.09, 342/452, 370/331, 370/332
• US Class Current: 455/440
• 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

A mobile communication system which performs a handover operation with high-reliability, while the system can flexibly cope with various circumstances in which a mobile station is used, without changing a hardware structure. A plurality of radio base stations form respective radio communication cells. Each of the radio base stations performs a radio channel setting control including a handover with respect to a call originated for the mobile station located in one of the cells. An exchange is connected to each of the radio base stations via a communication link so that the exchange performs a call process of the call in association with the radio channel setting control performed by the radio base stations. After the call becomes a completed call and prior to a handover operation, a movement of the mobile station from one of the cells in which the mobile station is located to another one of the cells adjacent to the one of the cells is predicted based on at least one of procedures of the radio channel setting control and the call process. When the movement is predicted so as to select candidate cells which are candidates of a transferee of the completed call, a free radio channel of the cells is acquired. A path connected to the acquired free radio channel is formed in the communication link.

Claims

1. A mobile communication system comprising:

a plurality of radio base stations forming respective radio communication zones according to one of a small zone structure and a sector structure, each of said radio base stations performing a radio channel setting control including a handover with respect to a call originated for a mobile station located in one of said radio communication zones; and

an exchange connected to each of said radio base stations via a communication link so that said exchange performs a call process of said call in association with the radio channel setting control performed by said radio base stations,

said mobile communication system further comprising;

a movement predicting unit which predicts, after said call becomes a completed call and prior to a handover operation, a movement of said mobile station from one of said radio communication zones in which said mobile station is located to another one of said communication zones adjacent to said one of said radio communication zones, a prediction of said movement being performed based on at least one of procedures of the radio channel setting control and the call process;

a candidate zone selecting unit which is activated when said movement is predicted by said movement predicting unit so as to select candidate radio communication zones which are candidates for transferring said completed call to, based on said predicted movement, said candidate zone selecting unit forming a communication path to said candidate radio communication zones, said communication path to be connected to a radio channel in said communication link prior to initiation of a handover to a radio communication zone from among said candidate radio communication zones, wherein an asynchronous transfer mode is applied to said communication link, and said candidate zone selecting unit logically forms a path without occupying a transmission band of said communication link,

wherein said radio base station and said exchange include means for acquiring a transmission band of a path formed by said candidate zone selecting unit with respect to the candidate radio communication zone which corresponds to a radio communication zone selected for handover of the completed call based on procedures of the radio channel setting control and the call process.

2. The mobile communication system as claimed in claim 1, wherein said radio base station and said exchange include means for determining whether or not the candidate radio communication zone selected by said candidate zone selecting unit has a possibility to become a radio communication zone selected for handover of a completed call based on the procedures of the radio channel setting control and the call process so as to release the acquired transmission band of a path of a candidate radio communication path to which a negative result of a determination is made.

3. A mobile communication system comprising:

a plurality of radio base stations forming respective radio communication zones according to one of a small zone structure and a sector structure, each of said radio base stations performing a radio channel setting control including a handover with respect to a call originated for a mobile station located in one of said radio communication zones; and

an exchange connected to each of said radio base stations via a communication link so that said exchange performs a call process of said call in association with the radio channel setting control performed by said radio base stations,

said mobile communication system further comprising;

a movement predicting unit which predicts, after said call becomes a completed call and prior to a handover operation, a movement of said mobile station from one of said radio communication zones in which said mobile station is located to another one of said communication zones adjacent to said one of said radio communication zones, a prediction of said movement being performed based on at least one of procedures of the radio channel setting control and the call process; and

a candidate zone selecting unit which is activated when said movement is predicted by said movement predicting unit so as to select candidate radio communication zones which are candidates for transferring said completed call to, based on said predicted movement, said candidate zone selecting unit forming a communication path corresponding to said communication link to said candidate radio communication zones,

wherein each of said radio base stations includes means for determining whether or not a radio communication zone selected for handover corresponds to one of said radio communication zones during a process of a handover of said completed call, and for acquiring a free radio channel of said one of said candidate radio communication zones when a result of a determination is affirmative and after initiation of a handover to said one of said radio communication zones, said means connecting said acquired free radio channel to the communication link formed by said candidate zone selecting unit.

4. The mobile communication system as claimed in claim 3, further comprising:

a zone structure storing unit in which a correspondence between each of said plurality of radio communication zones and an exchange controlling radio base stations forming the respective radio communication zones is previously stored,

wherein said candidate zone selecting unit includes means for selecting, from among the selected candidate radio communication zones, a candidate radio communication zone formed by a radio base station controlled by an exchange which is different from an exchange having a radio base station forming a radio communication zone corresponding to a radio communication zone selected for handover by referring to the correspondence stored in said zone structure storing unit so as to exclude remaining candidate radio communication zones other that said candidate radio communication zone based on an attribute of a completed call obtained based on at least one of the radio channel setting control and the call process, and the attribute of the completed call of which candidate radio communication zone is to be excluded is a service quality required for the completed call which should be less than a predetermined threshold value.

5. The mobile communication system as claimed in claim 3, further comprising an adjacent zone storing unit in which discrimination information with respect to each of said plurality of radio communication zones is stored,

wherein said candidate zone selecting unit determines whether or not a service quality required for the completed call is greater than a predetermined threshold level so as to obtain all of radio communication zones adjacent to the radio communication zone in which said mobile station having a completed call is located when a result of a determination is affirmative, said candidate zone selecting unit selecting the obtained radio communication zones as the candidate radio communication zones.

6. The mobile communication system as claimed in claim 3, wherein an asynchronous transfer mode is applied to said communication link, and said candidate zone selecting unit logically forms a communication path without occupying a transmission band of said communication link,

wherein said radio base station and said exchange include means for acquiring a transmission band of a communication path formed by said candidate zone selecting unit with respect to the candidate radio communication zone which corresponds to a candidate radio communication zone selected for handover of the completed call based on procedures of the radio channel setting control and the call process.

7. The mobile communication system as claimed in claim 6, wherein said radio base station and said exchange include means for determining whether or not the candidate radio communication zone selected by said candidate zone selecting unit has a possibility to become a candidate radio communication zone selected for handover of a completed call based on the procedures of the radio channel setting control and the call process so as to release the acquired transmission band of a path of a candidate radio communication path to which a negative result of a determination is made.

8. The mobile communication system as claimed in claim 3, wherein said exchange includes means for obtaining a priority of services required for a completed call based on the procedure of the call process, and said candidate zone selecting unit includes means for setting a higher value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the priority obtained by said exchange is increased.

9. The mobile communication system as claimed in claim 3, wherein said exchange includes means for obtaining a service quality required for a completed call based on the procedure of the call process, and said candidate zone selecting unit includes means for setting a higher value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the service quality obtained by said exchange is increased.

10. The mobile communication system as claimed in claim 3, wherein said exchange includes means for obtaining an amount of resources assigned to a completed call, and said candidate zone selecting unit includes means for setting a higher value to an upper limit value of a number of selectable candidate radio communication zones with respect of said completed call as the amount of resources obtained by said exchange is increased.

11. The mobile communication system as claimed in claim 3, wherein said exchange includes means for obtaining an amount of resources assigned to a completed call, and said candidate zone selecting unit includes means for setting a lower value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the amount of resources obtained by said exchange is increased.

12. The mobile communication system as claimed in claim 3, wherein said exchange includes means for measuring its call incompletion rate of probability, and said candidate zone selecting unit sets a lower value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the rate of probability measured by said exchange is increased.

13. The mobile communication system as claimed in claim 3, wherein said exchange includes means for measuring a level of congestion of said exchange, and said candidate zone selecting unit sets a lower value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the level of congestion measured by said exchange is increased.

14. The mobile communication system as claimed in claim 3, wherein said exchange includes means for determining whether or not a candidate radio communication zone selected for handover of the completed call of said mobile station corresponds to one of the candidate radio communication zones selected by said candidate zone selecting unit in a process of a handover of the completed call so as to determine whether a method for releasing or a method for storing is applied to a communication link set to the candidate radio communication zone when a result of a determination is negative.

15. The mobile communication system as claimed in claim 3, wherein said exchange includes means for determining whether to acquire a free radio channel after a completion of a setting of a communication link by said candidate zone selecting unit or to perform a handover without waiting for the completion of the setting of the communication link when a handover request is generated by said mobile station during a setting operation of the communication link by said candidate zone selecting unit.

16. The mobile communication system as claimed in claim 3, wherein said exchange predicts a time when a setting of the communication link is completed by said candidate zone selecting unit and a time when a handover request is generated, and when it is determined that the time when the setting of the communication link and the time when the handover request is generated are short, said exchange performs a handover and otherwise said exchange performs a setting of the communication link prior to a handover.

17. The mobile communication system as claimed in claim 3, wherein said exchange does not perform a setting of a communication link by said candidate zone selecting unit when a level of use of it own resources exceeds a predetermined threshold value.

18. The mobile communication system as claimed in claim 3, further comprising a moving pattern storing unit in which a moving pattern is previously registered, said moving pattern indicated by a permutation of discrimination information with respect to said radio communication zones through which one of a railway or a road crosses,

wherein said candidate zone selecting unit selects, as said candidate radio communication zones, subsequent radio communication zones indicated by a moving pattern having a high correlation with said moving pattern registered in said moving pattern storing unit, the moving pattern having a high correlation corresponding to a train of discrimination information including a current radio communication zone in which said mobile station is currently located and a previous radio communication zone in which said mobile station was previously located.

19. The mobile communication system as claimed in claim 3, further comprising a moving pattern storing unit in which a moving pattern announced by a subscriber of said mobile station is previously registered, said moving pattern indicated by a permutation of discrimination information with respect to said radio communication zones through which one of a railway or a road crosses so that said mobile station moves along said one of the railway or the road with a high probability,

wherein said candidate zone selecting unit selects, as said candidate radio communication zones, subsequent radio communication zones indicated by a moving pattern having a high correlation with said moving pattern registered in said moving pattern storing unit, the moving pattern having a high correlation corresponding to a train of discrimination information including a current radio communication zone in which said mobile station is currently located and a previous radio communication zone in which said mobile station was previously located.

20. The mobile communication system as claimed in claim 3, further comprising a moving pattern history unit which obtains a history of the radio communication zones in which said mobile station is located from among said plurality of radio communication zones so as to record the history as a train of discrimination information with respect to the radio communication zones without cooperating with said mobile station,

wherein said candidate zone selecting unit selects, as said candidate radio communication zones, subsequent radio communication zones indicated by a moving pattern having a high correlation with a moving pattern recorded in said moving pattern history unit with respect to a mobile station in which a completed call is originated, the moving pattern having a high correlation corresponding to a train of discrimination information including a current radio communication zone in which said mobile station is currently located and a previous radio communication zone in which said mobile station was previously located.

21. The mobile communication system as claimed in claim 3, further comprising a moving pattern history unit which obtains a history of the radio communication zones in which said mobile station is located from among said plurality of radio communication zones so as to record the history as a train of discrimination information with respect to the radio communication zones by cooperating with said mobile station,

wherein said candidate zone selecting unit selects, as said candidate radio communication zones, subsequent radio communication zones indicated by a moving pattern having a high correlation with said moving pattern recorded in said moving pattern history unit with respect to a mobile station in which a completed call is originated, the moving pattern having a high correlation corresponding to a train of discrimination information including a current radio communication zone in which said mobile station is currently located and a previous radio communication zone in which said mobile station was previously located.

22. The mobile communication system as claimed in claim 3, further comprising a shift probability storing unit which stores a probability to become a radio communication zone to be handover with respect to each of said plurality of radio communication zones, the probability being previously obtained by a simulation or an actual measurement based on a distribution of at least one of a road and a railway and a distribution of a traffic of said mobile station in at least one of the road and the railway,

wherein said candidate zone selecting unit includes means for excluding a candidate radio communication zone having the probability less than a predetermined lower limit value from among the probabilities registered in said shift probability storing unit or providing a higher priority as the probability of shift is higher.

23. The mobile communication system as claimed in claim 3, further comprising an adjacent zone storing unit in which discrimination information of the radio communication zones adjacent to each of said plurality of radio communication zones is registered,

wherein said candidate zone selecting unit includes means for determining whether or not the selected candidate radio communication zone corresponds to a radio communication zone adjacent to a radio communication zone which receives a handover so as to exclude a candidate radio communication zone to which a negative result of a determination is made.

24. The mobile communication system as claimed in claim 3, further comprising a zone structure storing unit in which a correspondence between each of said plurality of radio communication zones and an exchange controlling radio base stations forming the respective radio communication zones is previously stored,

wherein said candidate zone selecting unit includes means for selecting, from among the selected candidate radio communication zones, a candidate radio communication zone formed by a radio base station controlled by an exchange which is different from an exchange having a radio base station forming a radio communication zone which receives a handover by referring to the correspondence stored in said zone structure storing unit so as to exclude remaining candidate radio communication zones other than said candidate radio communication zone based on an attribute of a completed call obtained based on at least one of the radio channel setting control and the call process.

25. The mobile communication system as claimed in claim 3, further comprising an adjacent zone storing unit in which discrimination information with respect to each of said plurality of radio communication zones is stored,

wherein said candidate zone selecting unit determines whether or not a service quality required for the completed call is greater than a predetermined threshold level so as to obtain all of radio communication zones adjacent to the radio communication zone in which said mobile station having a completed call is located when a result of a determination is affirmative, said candidate zone selecting unit selecting the obtained radio communication zones as the candidate radio communication zones.

26. The mobile communication system as claimed in claim 3, further comprising a moving speed measuring unit which measures a speed of movement of said mobile station in which a completed call is originated,

wherein said candidate zone selecting unit sets a higher value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the speed measured by said moving speed measuring unit is increased.

27. The mobile communication system as claimed in claim 3, further comprising a transmission quality measuring unit which measures a transmission quality at a predetermined frequency with respect to a completed call,

wherein said movement predicting unit predicts whether said mobile station in which said completed call is originated moves to one of the adjacent radio communication zones when the transmission quality is measured by said transmission quality measuring unit.

28. The mobile communication system as claimed in claim 3, further comprising a transmission quality measuring unit which measures a transmission quality at a predetermined frequency with respect to a completed call,

wherein said movement predicting unit predicts that said mobile station in which said completed call is generated moves to one of the adjacent radio communication zones when the transmission quality of a current radio communication zone is less than a predetermined threshold value or when the transmission quality of one of the adjacent radio communication zones is greater than the predetermined threshold value.

29. The mobile communication system as claimed in claim 3, further comprising a transmission quality measuring unit which measures a transmission quality and a rate of change in the transmission quality at a predetermined frequency with respect to a completed call,

wherein said movement predicting unit predicts a moment when said mobile station in which said completed call is generated moves to one of the adjacent radio communication zones when the transmission quality of a current radio communication zone is less than a predetermined threshold value and based on the rate of change measured by said transmission quality measuring unit or when the transmission quality of one of the adjacent radio communication zones is greater than the predetermined threshold value and based on the rate of change measured by said transmission quality measuring unit.

30. The mobile communication system as claimed in claim 3, further comprising a moving speed measuring unit which measures a speed of movement of said mobile station in which a completed call is originated, wherein said movement predicting unit predicts a moment of movement of said mobile station to one of the adjacent radio communication zones to be earlier as the speed measured by said moving speed measuring unit is increased.

31. The mobile communication system as claimed in claim 3, further comprising a distance storing unit in which a geographic distance between adjacent radio communication zones for all combinations of two radio communication zones in said plurality of radio communication zones is stored,

wherein said radio base station and said exchange comprise means for releasing a communication path formed by said candidate zone selecting unit, the communication path being formed for a candidate radio communication zone having the distance registered in said distance storing unit as a combination of radio communication zones corresponding to a radio communication zone receiving a handover which is greater than a predetermined threshold value from among candidate radio communication zones selected by said candidate zone selecting unit.

32. The mobile communication system as claimed in claim 3, wherein said exchange includes means for determining whether or not a radio communication zone receiving a handover of said mobile station corresponds to one of the candidate radio communication zones selected by said candidate zone selecting unit in a process of a handover of the completed call so as to use a communication link set to the candidate radio communication zone for a call or a handover when a result of a determination is negative.

50. The mobile communication system as claimed in claim 31, further comprising an adjacent zone storing unit in which discrimination information with respect to each of said plurality of radio communication zones is stored,

wherein said candidate zone selecting unit determines whether or not a service quality required for the completed call is greater than a predetermined threshold level so as to obtain all of radio communication zones adjacent to the radio communication zone in which said mobile station having a completed call is located when a result of a determination is affirmative, said candidate zone selecting unit selecting the obtained radio communication zones as the candidate radio communication zones.

33. A mobile communication system comprising:

a mobile station which can be located in one of a plurality of radio communication zones according to a small zone structure or a sector structure;

a plurality of radio base stations forming said respective radio communication zones, each of said radio base stations performing a radio channel setting control including a handover with respect to a call originated for said mobile station located in one of said radio communication zones; and

an exchange connected to each of said radio base stations via a communication link so that said exchange performs a call process of said call in association with the radio channel setting control performed by said radio base stations,

said mobile communication system further comprising;

a candidate zone notification unit which selects, after said call becomes a completed call, candidate radio communication zones which are candidates for transferring the completed call to so as to announce the candidate radio communication zones to said mobile station; and

a candidate zone selecting unit which forms a communication path in said communication link to said candidate radio communication zones and acquires a free radio channel of the candidate radio communication zones selected by said candidate zone selecting unit when a request is provided from said mobile station and after initiation of a handover, and connects a communication path to said free radio channel,

wherein said mobile station includes a movement predicting unit which predicts a movement of said mobile station from one of said radio communication zones in which said mobile station is located to another one of said radio communication zones adjacent to said one of said radio communication zones, and when a result of a prediction indicates one of the candidate radio communication zones announced by said candidate zone notification unit, said movement predicting unit provides the result to said candidate zone selecting unit as said request.

34. The mobile communication system as claimed in claim 33, further comprising a moving pattern storing unit in which a moving pattern is previously registered, said moving pattern indicated by a permutation of discrimination information with respect to said radio communication zones through which one of a railway or a road crosses,

wherein said candidate zone selecting unit selects, as said candidate radio communication zones, subsequent radio communication zones indicated by a moving pattern having a high correlation with said moving pattern registered in said moving pattern storing unit, the moving pattern having a high correlation corresponding to a train of discrimination information including a current radio communication zone in which said mobile station is currently located and a previous radio communication zone in which said mobile station was previously located.

35. The mobile communication system as claimed in claim 33, further comprising a moving pattern storing unit in which a moving pattern announced by a subscriber of said mobile station is previously registered, said moving pattern indicated by a permutation of discrimination information with respect to said radio communication zones through which one of a railway or a road crosses so that said mobile station moves along said one of the railway or the road with a high probability,

wherein said candidate zone selecting unit selects, as said candidate radio communication zones, subsequent radio communication zones indicated by a moving pattern having a high correlation with said moving pattern registered in said moving pattern storing unit, the moving pattern having a high correlation corresponding to a train of discrimination information including a current radio communication zone in which said mobile station is currently located and a previous radio communication zone in which said mobile station was previously located.

36. The mobile communication system as claimed in claim 33, further comprising a moving pattern history unit which obtains a history of the radio communication zones in which said mobile station is located from among said plurality of radio communication zones so as to record the history as a train of discrimination information with respect to the radio communication zones without cooperating with said mobile station,

wherein said candidate zone selecting unit selects, as said candidate radio communication zones, subsequent radio communication zones indicated by a moving pattern having a high correlation with a moving pattern recorded in said moving pattern history unit with respect to a mobile station in which a completed call is originated, the moving pattern having a high correlation corresponding to a train of discrimination information including a current radio communication zone in which said mobile station is currently located and a previous radio communication zone in which said mobile station was previously located.

37. The mobile communication system as claimed in claim 33, further comprising a moving pattern history unit which obtains a history of the radio communication zones in which said mobile station is located from among said plurality of radio communication zones so as to record the history as a train of discrimination information with respect to the radio communication zones by cooperating with said mobile station,

wherein said candidate zone selecting unit selects, as said candidate radio communication zones, subsequent radio communication zones indicated by a moving pattern having a high correlation with said moving pattern recorded in said moving pattern history unit with respect to a mobile station in which a completed call is originate, the moving pattern having a high correlation corresponding to a train of discrimination information including a current radio communication zone in which said mobile station is currently located and a previous radio communication zone in which said mobile station was previously located.

38. The mobile communication system as claimed in claim 33, further comprising a shift probability storing unit which stores a probability to become a radio communication zone to be handover with respect to each of said plurality of radio communication zones, the probability being previously obtained by a simulation or an actual measurement based on a distribution of at least one of a road and a railway and a distribution of a traffic of said mobile station in at least one of the road and the railway,

wherein said candidate zone selecting unit includes means for excluding a candidate radio communication zone having the probability less than a predetermined lower limit value from among the probabilities registered in said shift probability storing unit or providing a higher priority as the probability of shift is higher.

39. The mobile communication system as claimed in claim 33, further comprising an adjacent zone storing unit in which discrimination information of the radio communication zones adjacent to each of said plurality of radio communication zones is registered,

wherein said candidate zone selecting unit includes means for determining whether or not the selected candidate radio communication zone corresponds to a radio communication zone adjacent to a radio communication zone which is a transferee so as to exclude a candidate radio communication zone to which a negative result of a determination is made.

40. The mobile communication system as claimed in claim 33, further comprising a zone structure storing unit in which a correspondence between each of said plurality of radio communication zones and an exchange controlling radio base stations forming the respective radio communication zones is previously stored,

wherein said candidate zone selecting unit includes means for selecting, from among the selected candidate radio communication zones, a candidate radio communication zone formed by a radio base station controlled by an exchange which is different from an exchange having a radio base station forming a radio communication zone corresponding to a transferee by referring to the correspondence stored in said zone structure storing unit so as to exclude remaining candidate radio communication zones other than said candidate radio communication zone based on an attribute of a completed call obtained based on at least one of the radio channel setting control and the call process.

41. The mobile communication system as claimed in claim 33, further comprising an adjacent zone storing unit in which discrimination information with respect to each of said plurality of radio communication zones is stored,

wherein said candidate zone selecting unit determines whether or not a service quality required for the completed call is greater than a predetermined threshold level so as to obtain all of radio communication zones adjacent to the radio communication zone in which said mobile station having a completed call is located when a result of a determination is affirmative, said candidate zone selecting unit selecting the obtained radio communication zones as the candidate radio communication zones.

42. The mobile communication system as claimed in claim 33, further comprising a moving speed measuring unit which measures a speed of movement of said mobile station in which a completed call is originated,

wherein said candidate zone selecting unit sets a higher value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the speed measured by said moving speed measuring unit is increased.

43. The mobile communication system as claimed in claim 33, further comprising a transmission quality measuring unit which measures a transmission quality at a predetermined frequency with respect to a completed call,

wherein said movement predicting unit predicts whether said mobile station in which said completed call is originated moves to one of the adjacent radio communication zones when the transmission quality is measured by said transmission quality measuring unit.

44. The mobile communication system as claimed in claim 33, further comprising a transmission quality measuring unit which measures a transmission quality at a predetermined frequency with respect to a completed call,

wherein said movement predicting unit predicts that said mobile station in which said completed call is generated moves to one of the adjacent radio communication zones when the transmission quality of a current radio communication zone is less than a predetermined threshold value or when the transmission quality of one of the adjacent radio communication zones is greater than the predetermined threshold value.

45. The mobile communication system as claimed in claim 33, further comprising a transmission quality measuring unit which measures a transmission quality and a rate of change in the transmission quality at a predetermined frequency with respect to a completed call,

wherein said movement predicting unit predicts a movement when said mobile station in which said completed call is generated moves to one of the adjacent radio communication zones when the transmission quality of a current radio communication zone is less than a predetermined threshold value and based on the rate of change measured by said transmission quality measuring unit or when the transmission quality of one of the adjacent radio communication zones is greater than the predetermined threshold value and base on the rate of change measured by said transmission quality measuring unit.

46. The mobile communication system as claimed in claim 33, further comprising a moving speed measuring unit which measures a speed of movement of said mobile station in which a completed call is originated,

wherein said movement predicting unit predicts a movement of movement of said mobile station to one of the adjacent radio communication zones to be earlier as the speed measured by said moving speed measuring unit is increased.

47. The mobile communication system as claimed in claim 33, further comprising a distance storing unit in which a geographic distance between adjacent radio communication zones for all combinations of two radio communication zones in said plurality of radio communication zones,

wherein said radio base station and said exchange comprise means for releasing a path formed by said candidate zone selecting unit, the path being formed for a candidate radio communication zone having the distance registered in said distance storing unit as a combination of radio communication zones corresponding to a transferee which is greater than a predetermined threshold value from among candidate radio communication zones selected by said candidate zone selecting unit.

48. The mobile communication system as claimed in claim 33, wherein said exchange includes means for determining whether or not a transferee of said mobile station corresponds to one of the candidate radio communication zones selected by said candidate zone selecting unit in a process of a handover of the completed call so as to use a communication link set to the candidate radio communication zone for a call or a handover when a result of a determination is negative.

49. The mobile communication system as claimed in claim 33, further comprising:

a zone structure storing unit in which a correspondence between each of said plurality of radio communication zones and an exchange controlling radio base stations forming the respective radio communication zones is previously stored,

wherein said candidate zone selecting unit includes means for selecting, from among the selected candidate radio communication zones, a candidate radio communication zone formed by a radio base station controlled by an exchange which is different from an exchange having a radio base station forming a radio communication zone corresponding to a radio communication zone selected for handover by referring to the correspondence stored in said zone structure storing unit so as to exclude remaining candidate radio communication zones other that said candidate radio communication zone based on an attribute of a completed call obtained based on at least one of the radio channel setting control and the call process, and the attribute of the completed call of which candidate radio communication zone is to be excluded is a service quality required for the completed call which should be less than a predetermined threshold value.

51. The mobile communication system as claimed in claim 33, wherein an asynchronous transfer mode is applied to said communication link, and said candidate zone selecting unit logically forms a communication path without occupying a transmission band of said communication link,

wherein said radio base station and said exchange include means for acquiring a transmission band of a communication path formed by said candidate zone selecting unit with respect to the candidate radio communication zone which corresponds to a candidate radio communication zone selected for handover of the completed call based on procedures of the radio channel setting control and the call process.

52. The mobile communication system as claimed in claim 51, wherein said radio base station and said exchange include means for determining whether or not the candidate radio communication zone selected by said candidate zone selecting unit has a possibility to become a candidate radio communication zone selected for handover of a completed call based on the procedures of the radio channel setting control and the call process so as to release the acquired transmission band of a path of a candidate radio communication path to which a negative result of a determination is made.

53. The mobile communication system as claimed in claim 33, wherein said exchange includes means for obtaining a priority of services required for a completed call based on the procedure of the call process, and said candidate zone selecting unit includes means for setting a higher value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the priority obtained by said exchange is increased.

54. The mobile communication system as claimed in claim 33, wherein said exchange includes means for obtaining a service quality required for a completed call based on the procedure of the call process, and said candidate zone selecting unit includes means for setting a higher value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the service quality obtained by said exchange is increased.

55. The mobile communication system as claimed in claim 33, wherein said exchange includes means for obtaining an amount of resources assigned to a completed call, and said candidate zone selecting unit includes means for setting a higher value to an upper limit value of a number of selectable candidate radio communication zones with respect of said completed call as the amount of resources obtained by said exchange is increased.

56. The mobile communication system as claimed in claim 33, wherein said exchange includes means for obtaining an amount of resources assigned to a completed call, and said candidate zone selecting unit includes means for setting a lower value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the amount of resources obtained by said exchange is increased.

57. The mobile communication system as claimed in claim 33, wherein said exchange includes means for measuring its call incompletion rate of probability, and said candidate zone selecting unit sets a lower value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the rate of probability measured by said exchange is increased.

58. The mobile communication system as claimed in claim 33, wherein said exchange includes means for measuring a level of congestion of said exchange, and said candidate zone selecting unit sets a lower value to an upper limit value of a number of selectable candidate radio communication zones with respect to said completed call as the level of congestion measured by said exchange is increased.

59. The mobile communication system as claimed in claim 33, wherein said exchange includes means for determining whether or not a candidate radio communication zone selected for handover of the completed call of said mobile station corresponds to one of the candidate radio communication zones selected by said candidate zone selecting unit in a process of a handover of the completed call so as to determine whether a method for releasing or a method for storing is applied to a communication path set to the candidate radio communication zone when a result of a determination is negative.

60. The mobile communication system as claimed in claim 33, wherein said exchange includes means for determining whether to acquire a free radio channel after a completion of a setting of a communication path by said candidate zone selecting unit or to perform a handover without waiting for the completion of the setting of the communication path when a handover request is generated by said mobile station during a setting operation of the communication path by said candidate zone selecting unit.

61. The mobile communication system as claimed in claim 33, wherein said exchange predicts a time when a setting of the communication path is completed by said candidate zone selecting unit and a time when a handover request is generated, and when it is determined that the time when the setting of the communication path and the time when the handover request is generated are short, said exchange performs a handover and otherwise said exchange performs a setting of the communication path prior to a handover.

62. The mobile communication system as claimed in claim 33, wherein said exchange does not perform a setting of a communication path by said candidate zone selecting unit when a level of use of it own resources exceeds a predetermined threshold value.

63. A mobile communication system comprising:

a mobile station which can be located in one of a plurality of radio communication zones according to a small zone structure or a sector structure;

a plurality of radio base stations forming said respective radio communication zones, each of said radio base stations performing a radio channel setting control including a handover with respect to a call originated for said mobile station located in one of said radio communication zones; and

an exchange connected to each of said radio base stations via a communication link so that said exchange performs a call process of said call in association with the radio channel setting control performed by said radio base stations,

said mobile communication system further comprising;

a candidate zone notification unit which selects, after said call becomes a completed call, candidate radio communication zones which are candidates for transferring the completed call to so as to announce the candidate radio communication zones to said mobile station; and

a candidate zone selecting unit which selects the candidate radio communication zones selected by said candidate zone notification unit when a request is provided from said mobile station, and forms a communication link to the radio base station in said candidate radio communication zones,

wherein said mobile station includes a movement predicting unit which predicts a movement of said mobile station from one of said radio communication zones in which said mobile station is located to another one of said radio communication zones adjacent to said one of said radio communication zones, and when a result of a prediction indicates one of the candidate radio communication zones announced by said candidate zone notification unit, said movement predicting unit provides the result to said candidate zone selecting unit as said request; and

each of said radio base stations includes means for determining whether or not a radio communication zone selected for handover corresponds to one of said radio communication zones during a process of a handover of said completed call, and for acquiring a free radio channel of said one of said candidate radio communication zones when a result of a determination is affirmative and after initiation of a handover sequence to said one of said radio communication zones, said means connecting said acquired free radio channel to the communication link formed by said candidate zone selecting unit.