HK1087295B - Communication system, method thereof, switching center thereof and base station control station thereof - Google Patents

Description

Communication system, communication method, switching center and base station control station

The application is a divisional application with the application number of 01813999.X (PCT/JP01/06932), the application date of 2001, 8 months and 10 days, and the invention name of 'communication system and communication method, and a switching center and a base station control station thereof'.

Technical Field

The present invention relates to a communication system, a communication method, a switching center and a base station control station thereof, and more particularly to a communication system of a W-CDMA (Wideband Code Division multiple access) system, the communication system including: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the base station console and the communication network.

Background

Such a communication system is explained with reference to fig. 1. Fig. 1 is a schematic block diagram showing a conceptual system configuration of such a communication system.

The illustrated communication system has first to fourth base stations 3-1, 3-2, 3-3 and 3-4, which have first to fourth cells A1, A2, A3 and A4 of wireless service areas under their control, respectively.

In the illustrated example, the first and second base stations 3-1 and 3-2 are under management control by a first wireless management Network (RNC: Radio Network Controller), and the third and fourth base stations 3-3 and 3-4 are under management control by a second wireless management Network 2-2. These first and second wireless management networks 2-1 and 2-2 are generally referred to as wireless base station control stations, and hereinafter referred to as base station control stations in this specification.

These first and second base station consoles 2-1 and 2-2 are connected to a Core Network (Core Network)1 located further up, which Core Network 1 is shown to also comprise a communication Network. The core network 1 performs a circuit connection switching process and the like between the communication network and the user terminal 4 as a mobile station in the first to fourth cells a1 to a 4. In the illustrated example, the user terminal 4 is located within a second cell a 2. The core network 1 basically has a function as a switching center, and is hereinafter referred to as a switching center in this specification.

Fig. 2 sequentially shows an example of operations performed when a certain user receives a certain communication service using the user terminal 4 in the communication system shown in fig. 1.

In this case, first, a call containing information indicating the service type is made from the user terminal 4. The call is sent to the second base station 3-2, the first base station console 2-1 and the switching center 1. The switching center 1 transmits an RAB (radio access Bearer) setup request message to the first base station console 2-1 in response to the call. In this case, the RAB setup request message contains the requested bit rate information following the communication service requested by the user terminal.

The first base station control station 2-1 receives the RAB setup request message including the requested bit rate information, and determines the use state of the resources (lines) managed by itself. This usage situation is also the usage situation of resources in the second cell a2 of the second base station 3-2 service area. If a resource satisfying the requested bit rate can be secured, the first base station console 2-1 determines that the communication service can be implemented using the requested bit rate. Then, the first base station console 2-1 transmits this to the switching center 1 as an RAB setup response message. The switching center 1 receives the response message, considers that the call from the user terminal 4 is successful, and starts the communication service of the requested bit rate.

On the other hand, the first base station control station 2-1 constantly monitors the use state of the resources managed by itself. When it is determined that the line satisfying the requested bit rate cannot be set due to insufficient resources, the first base station control station 2-1 transmits a message indicating that the bit rate is changed to a bit rate lower than the requested bit rate to the switching center 1 as an RAB setup response message. Upon receiving the response message, the switching center 1 performs an operation in either of the following two cases. In the first case, the switching center 1 considers that the call from the user terminal 4 is successful and starts the communication service using a bit rate lower than the requested bit rate. In the second case, the switching center 1 determines that the bit rate is not suitable for the communication service requested by the user terminal, and transmits an RAB release request message to the first base station console 2-1. Then, in this case, an RAB release response message is sent from the base station control station, and the switching center cannot forward the call.

Further, as communication services that the user wants to receive, there are image data services including still images and moving images, audio and video data services that add audio to images, and the like.

Communication services that a user wants to receive, such as image data services like real-time video data, will require a high bit rate. In this case, if communication is performed at a bit rate lower than that, the user terminal cannot receive a required amount of data in a short time as the transmission speed decreases. As a result, the image displayed on the actual user terminal becomes unnatural.

Therefore, as described above, if the base station control station arbitrarily determines a low bit rate other than the desired bit rate instructed from the switching center 1 to the base station control station, a bit rate resource that the user satisfies cannot be secured, and thus data transmission cannot be performed smoothly.

If the service cannot be provided using the low bit rate arbitrarily determined by the base station control station, the switching center has already made a judgment. In this case, there is also a disadvantage that the switching center 1 needs to transmit a release request message as shown in fig. 2 in order to release the resources captured by the base station control station, which increases unnecessary signal processing.

Therefore, an object of the present invention is to provide a communication system and a communication method, a switching center and a base station control station thereof, that is: even when a communication rate corresponding to a communication service desired by a user cannot be secured due to insufficient resources, data transmission can be performed smoothly.

It is a specific object of the present invention to provide such a communication system and communication method, and a switching center and a base station control station therefor, that is: in the case where a desired bit rate cannot be secured due to insufficient resources, it is not mandatory to set a low bit rate and to perform bit rate adjustment between the switching center and the base station control station only when the base station control station can provide a service using a communication rate lower than the requested communication rate, so that data transmission can be performed smoothly.

Disclosure of Invention

According to the present invention, a communication system is obtained, the communication system comprising: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the plurality of base station control stations and the communication network; the switching center includes a transmission device for transmitting, in response to a call accompanying a communication service type from a user terminal existing in the cell, communication rate information corresponding to the communication service type of the call and an adjustable indicator indicating whether the communication rate is adjustable, to the base station controller when transmitting a line setup request message to the base station controller.

The base station control station further includes: a judging device, for responding the line setting request message, and judging the line shortage according to the communication rate information and the using state of the line managed by the base station console; and adjusting means for adjusting a communication rate of the communication service in accordance with the contents of the adjustable indicator when the line is short.

The base station control station further includes: deciding means for deciding communication rate information other than communication rate information corresponding to the call communication service type when it is determined that the line is insufficient and the adjustable indicator indicates adjustability; and a loopback means for looping back the decided communication rate information to the switching center together with a response message. The base station control station further includes a return means for returning a response message indicating that the line setup request has failed to the switching center when it is determined that the line is insufficient and the tuning indicator indicates that tuning is not possible.

According to the present invention, a communication system is obtained, the communication system comprising: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the base station console and the communication network; the switching center includes a transmission device for transmitting desired communication rate information corresponding to a communication service type of a call and adjustable communication rate information other than the desired communication rate to the base station control station when transmitting a line setup request message to the base station control station in response to the call accompanying the communication service type from a user terminal existing in the cell.

The base station control station further includes: a judging device, for responding the line setting request message, and judging the line shortage according to the expected communication rate information and the using state of the line managed by the base station console; and a determining device for determining one of the adjustable communication rate information as the communication rate of the communication service when the line is insufficient. The base station control station has a return means for returning the determined communication rate information to the switching center together with a response message.

The switching center includes a start device for starting a communication service for the call based on communication rate information returned from the base station control station, and the adjustable communication rate is a rate in a predetermined range smaller than the desired communication rate. The adjustable communication rate is a plurality of communication rates set in stages within the predetermined range.

The base station control station further includes a return means for returning a response message indicating that the line setup request has failed to the switching center when it is determined that the line is insufficient and the line setup request message does not include the adjustable communication rate information, the response message including information indicating that the line is insufficient as a cause of the failure.

According to the present invention, a communication method is obtained, the communication method including: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the base station console and the communication network; the switching center includes a transmission step of transmitting, in response to a call accompanying a communication service type from a user terminal existing in the cell, communication rate information corresponding to the communication service type of the call and an adjustable indicator indicating whether the communication rate is adjustable, to the base station controller when transmitting a line setup request message to the base station controller.

The base station control station further includes: a judging step of judging the shortage of the line according to the communication rate information and the use state of the line managed by the base station console in response to the line setting request message; and an adjusting step of adjusting a communication rate of the communication service according to the content of the adjustable indicator when the line is insufficient. The base station control station further includes: a determination step of determining communication rate information other than communication rate information corresponding to the call communication service type when it is determined that the line is insufficient and the adjustable indicator indicates adjustability; and a loopback step of looping back the decided communication rate information to the switching center together with a response message.

The base station control station further includes a return step of returning a response message indicating that the line setup request has failed to the switching center, when it is determined that the line is insufficient and the tuning indicator indicates that tuning is not possible.

According to the present invention, a communication method is obtained, the communication method including: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the base station console and the communication network; the switching center includes a transmission step of transmitting, when transmitting a line setup request message to the base station controller in response to a call associated with a communication service type from a user terminal existing in the cell, desired communication rate information corresponding to the communication service type of the call and adjustable communication rate information other than the desired communication rate.

The base station control station further includes: a judging step of judging the shortage of the line in response to the line setting request message, based on the expected communication rate information and the use state of the line managed by the base station console; and a determining step of determining one of the adjustable communication rate information as a communication rate of the communication service when the line is insufficient.

The base station control station includes a return step of returning the determined communication rate information to the switching center together with a response message. The switching center includes a starting step of starting a communication service for the call based on the communication rate information returned from the base station control station. The adjustable communication rate is a rate in a predetermined range smaller than the desired communication rate. The adjustable communication rate is a plurality of communication rates set in stages within the predetermined range.

According to the present invention, there is obtained a switching center, which is a switching center in a communication system comprising: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the base station console and the communication network; the switching center includes a transmission device for transmitting, when transmitting a line setup request message to the base station controller in response to a call associated with a communication service type from a user terminal existing in the cell, communication rate information corresponding to the communication service type of the call and an adjustable instruction signal indicating whether the communication rate is adjustable.

According to the present invention, there is obtained a switching center, which is a switching center in a communication system comprising: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the base station console and the communication network; the switching center includes a transmission device for transmitting desired communication rate information corresponding to a communication service type of a call and adjustable communication rate information other than the desired communication rate to the base station control station when transmitting a line setup request message to the base station control station in response to the call accompanying the communication service type from a user terminal existing in the cell.

According to the present invention, there is obtained a base station control station which is a base station control station in a communication system including: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the base station console and the communication network; the base station control station is characterized by comprising: receiving means for receiving, in response to a call accompanying a communication service type from a user terminal existing in the cell, communication rate information corresponding to the communication service type of the call included in the line setup request message transmitted from the switching center, and an adjustable indicator indicating whether the communication rate is adjustable; a judging device for judging the shortage of the line according to the communication rate information and the using state of the line managed by the base station console; and adjusting means for adjusting a communication rate of the communication service in accordance with the contents of the adjustable indicator when the line is short.

The base station control station further includes: deciding means for deciding communication rate information other than communication rate information corresponding to the call communication service type when it is determined that the line is insufficient and the adjustable indicator indicates adjustability; and a loopback means for looping back the decided communication rate information to the switching center together with a response message. The base station control station further includes a return means for returning a response message indicating that the line setup request has failed to the switching center when it is determined that the line is insufficient and the tuning indicator indicates that tuning is not possible.

According to the present invention, there is obtained a base station control station which is a base station control station in a communication system including: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the base station console and the communication network; the base station control station is characterized by comprising: receiving means for receiving, in response to a call accompanying a communication service type from a user terminal existing in the cell, desired communication rate information corresponding to the call communication service type included in the line setup request message transmitted from the switching center and adjustable communication rate information other than the desired communication rate; a judging device for judging the shortage of the line according to the expected communication rate information and the using state of the line managed by the base station console; and a determining device for determining one of the adjustable communication rate information as the communication rate of the communication service when the line is insufficient. Further, there is obtained a base station control station further having a loopback means for looping back the decided communication rate information to the switching center together with a response message.

According to the present invention, a communication system is obtained, the communication system comprising: a plurality of base stations each having a cell of a wireless service area; a base station control station for managing and controlling the base stations; and a switching center having a switching function for the base station console and the communication network; in the communication system, the switching center includes a transmission device for transmitting a line setup request message including communication rate information corresponding to a communication service type to the base station control station in response to a call associated with the communication service type from a user terminal existing in the cell; the base station control station has a determination device for determining whether or not the communication rate is adjustable, based on information in the line setup request message.

The information in the line setup request message is an option parameter of the line setup request message. Further, the determination device of the base station console determines that: if the option parameter exists, the communication rate is adjustable, and if the option parameter does not exist, the communication rate is not adjustable.

The operation of the present invention will be explained below. In the present invention, in the case where a desired communication rate cannot be secured due to insufficient resources, instead of being forcibly set to a lower alternative communication rate, the communication rate actually used for data communication is adjusted (negotiated) between the switching center and the base station control station only when the base station control station can provide a service using a communication rate lower than the requested communication rate.

As one of the specific methods, an indicator indicating whether the communication rate is adjustable or non-adjustable is provided in RAB setup request (line setup request) information transmitted from the switching center to the base station control station. Only in the case where the indicator indicates that the communication rate is adjustable, the base station control station determines a communication rate lower than the desired communication rate when the resources are insufficient, and transmits the communication rate information contained in the RAB setup response message to the switching center. According to the communication rate, a communication service of the user terminal is started.

As another method, if the service is a communication rate adjustable service, RAB setup request (line setup request) information transmitted from the switching center to the base station control station includes an adjustable communication rate in addition to a desired communication rate. Only in the case where the adjustable communication rate is included, the base station control station decides to use the adjustable communication rate when resources are insufficient, and transmits the communication rate information included in the RAB setup response message to the switching center. According to the communication rate, a communication service of the user terminal is started.

Drawings

Fig. 1 is a schematic block diagram of a communication system to which an embodiment of the present invention is applicable.

Fig. 2 shows a sequence diagram of an example of an operation using the background art.

Fig. 3 illustrates a sequence diagram representing the operation of a bit rate adjustable/non-adjustable indicator when indicating "adjustable" in an embodiment of the present invention.

Fig. 4 shows a diagram of the adjustable bit rate when the bit rate for a service type is adjustable/non-adjustable and adjustable in an embodiment of the invention.

Fig. 5 illustrates a sequence diagram representing the operation of a bit rate adjustable/non-adjustable indicator when indicating "non-adjustable" in an embodiment of the present invention.

Fig. 6 shows a sequence diagram operating in setting adjustable bit rate information in another embodiment of the present invention.

Fig. 7 shows a graph of an example of the adjustable bit rate information of fig. 5.

Fig. 8 shows a sequence diagram operating when adjustable bit rate information is not set in another embodiment of the present invention.

Detailed Description

The invention will be explained in more detail below with reference to the drawings.

Referring first to fig. 2, the system configuration of fig. 2 is directly applicable to embodiments of the present invention.

Fig. 3 is a sequence diagram showing an operation procedure among the user terminal 4, the first radio base station console 2-1, and the switching center 1 shown in fig. 1, showing an embodiment of the present invention. In fig. 3, when a call request is issued from the user terminal 4, the call request contains a communication service type that the user wants to receive a service. The call request is transmitted to the switching center 1 through the second base station 3-2 and the first base station console 2-1 regarding the second cell a2 to which the user terminal 4 belongs as a service area.

The switching center 1 transmits RAB Assignment Request (RAB Assignment Request) information of the line setup Request to the first base station control station 2-1 in response to the call Request. At this time, the information includes: bit rate information (request bit rate information) corresponding to a communication service type for which a user wants to receive a service, and an adjustable Indicator (Negotiable Indicator) indicating whether the request bit rate information is adjustable.

Here, the switching center 1 stores a table shown in fig. 4 in advance in a memory, for example, for a communication service type for which the user wants to receive a service. In fig. 4, services 1, 2, 4 are bit rate adjustable services, while service 3 is a bit rate non-adjustable service. Using this graph, the switching center 1 can make a decision as to whether the bit rate at which the user wants to receive the service is adjustable/non-adjustable. For example, in the case of service 1, a flag "1" indicating adjustability is displayed in the adjustable indicator.

Upon receiving the RAB setup request message, the first base station control station 2-1 refers to the desired bit rate included in the RAB setup request message, and determines whether or not the resources are insufficient based on the usage state of the resources (lines) managed by the local station (i.e., the current resource usage state in the second cell a2 of the second base station 3-2). If it is determined that the resources are insufficient, the adjustable indicator is set to "1", and thus the first base station console 2-1 makes a decision on a bit rate that is lower than the requested bit rate and within the resource range settable in the first base station console 2-1. Then, the first base station control station 2-1 sets the determined bit rate information in RAB assignment response (RAB assignment response) information, and returns the information to the switching center 1.

The base station control station often manages the resource status used by the subordinate base station. The management method uses a resource management table and performs management control according to the management table. Since a known management control method can be used, the description thereof will be omitted here.

Upon receiving an RAB setup response message in which a bit rate set in addition to the requested bit rate in the RAB setup request message is set, the switching center 1 provides a service to the user using the set bit rate, and thus the call is successful.

As shown in the sequence diagram of fig. 5, the tunable indicator of the RAB setup request message is set to "0" (i.e., set to non-tunable). In this case, a reason identifier (Cause) indicating that the resources are insufficient is added, and RAB Assignment Failure (RAB Assignment Failure) information is returned from the first base station control station 2-1 to the switching center 1. Upon receiving the RAB setup failure message, the switching center 1 determines that the service cannot be provided, considers that the call has failed, and starts call disconnection.

Also, in the sequence diagrams of fig. 3 and 5, the first base station console 2-1 will determine that the requested bit rate can be used to provide a service without a resource shortage. In this case, service can be provided using the requested bit rate, which of course is call success.

FIG. 6 is a sequence diagram of another embodiment of the present invention. In fig. 6, when a call request is issued from the user terminal 4, it is assumed that the call request contains a communication service type that the user wants to receive a service. The call request is transmitted to the switching center 1 through the second base station 3-2 and the first base station console 2-1 regarding the second cell a2 to which the user terminal 4 belongs as a service area.

The switching center 1 transmits an RAB setup request message to the first base station console 2-1 for the call request. At this time, the information includes: bit rate information (desired bit rate information) corresponding to a communication service type that a user wants to receive a service, and adjustable bit rate information decided according to the service type shown in fig. 4 in the case where the desired bit rate information is adjustable. As an example of the adjustable bit rate information, as shown in fig. 4, bit rates of a plurality of levels lower than the bit rate are predetermined. That is, service 1 is classified into 128 to 16kbps 4 class, service 2 is classified into 256 and 128kbps 2 class, and service 4 is classified into 64, 32, 16, and 8kbps 4 class. If the resources are insufficient, an attempt is made to set a bit rate that is one step lower than the desired bit rate (highest bit rate). For example, in the case of service 1, as shown in fig. 7, it is 128 kbps. When available resources are not obtained even with the use of 128kbps, an attempt is made to set a bit rate of 64kbps one step lower. If there is still insufficient resources, further attempts are made to set a bit rate of 32kbps one more lower.

In this way, if it is determined that the available resources are available, the first base station console 2-1 determines the bit rate, sets the determined bit rate information in the RAB setup response message, and returns the information to the switching center 1. Using this bit rate, the switching centre 1 can serve the user so that the call is successful.

As shown in the sequence diagram of fig. 8, it is assumed that the adjustable bit rate information is not set in the RAB setup request message. At this time, when the resources are insufficient, the first base station controller 2-1 sets a reason identifier indicating that the resources are insufficient, and returns RAB setup failure information to the switching center 1. The switching centre 1 considers the call as failed and initiates a call disconnection.

In the embodiment shown in fig. 6, as the scalable bit rate information set in the RAB setup request, although the hierarchical bit rates shown in fig. 4 and 7 are used, information indicating a scalable range (upper and lower limits) may be set, and the base station console may decide the bit rate in the scalable range in the case of insufficient resources.

Also, the adjustable indicator shown in fig. 3 and the adjustable bit rate information shown in fig. 6 may be set to partially overlap with the header of the RAB setup request message. Also, as an option parameter, the RAB setup request message includes adjustable bit rate information. If the option parameter exists, the option parameter is adjustable, and if the option parameter does not exist, the option parameter is not adjustable. As a result, the switching center transmits a line setup request message including information indicating a communication rate to the base station control station in response to a call accompanying a communication service type from the user terminal existing in the cell. The base station control station may determine whether the communication rate is adjustable according to the information of the option parameter in the line setup request message, and therefore, the adjustable indicator may not be needed.

Also, although the functional block diagrams of the wireless base station control station and the switching center are not particularly shown, since the wireless base station control station collects the adjustable indicator and the adjustable bit rate information, the function of performing bit rate decision can be added to the existing function when resources are insufficient. It is obvious that this function can be realized by using only a CPU (arithmetic processing control unit of a computer or the like) and using an operation control program recorded in advance in a recording medium such as a ROM or the like.

And, the switching center may judge the adjustable indicator and the adjustable bit rate information according to the service type set in the call, and may add a function attached to the RAB setup request message to the existing function. It is obvious that this function can be realized by using the CPU and the operation control program recorded in advance in the recording medium such as the ROM.

As described above, according to the present invention, only in the case where a bit rate lower than a requested bit rate can be used to provide a service to a user, it is possible to perform adjustment (negotiation) of the bit rate between a switching center and a base station control station and provide the service, and therefore, there is an effect that data transmission can be smoothly achieved. On the other hand, when no service is provided using a bit rate lower than the requested bit rate, the switching center and the base station control station cannot adjust the bit rate and call disconnection is started.

Claims (30)

1. A communication system, the communication system comprising: a user terminal including a plurality of base stations (3-1 to 3-4) each having cells (A1 to A4) as wireless service areas; base station control tables (2-1-2); and a core network (1) having a switching function; wherein the content of the first and second substances,

the user terminal comprises means for sending a request to the core network;

the switching center in the core network comprises transmitting means for transmitting not only desired communication rate information but also adjustable communication rate information other than the desired communication rate when transmitting a line setup request message to the base station console after receiving a request from a user terminal (4) located in the cell.

2. The communication system according to claim 1, wherein the base station control station comprises: a judging device, which is used for judging the shortage of the line according to the expected communication rate information and the using state of the line managed by the base station console; and deciding means for deciding one of the pieces of adjustable communication rate information as a communication rate of the requested communication service in a case where a line is insufficient.

3. The communication system according to claim 2, wherein the base station control station includes a loopback means for looping back the decided communication rate information together with a response message to a switching center in the core network.

4. A communication system according to claim 3, wherein the switching centre in the core network comprises starting means for starting a communication service on the basis of the communication rate information returned from the base station control station.

5. A communication system as claimed in any of claims 1 to 4, wherein the adjustable communication rate is a rate within a predetermined range less than the desired communication rate.

6. The communication system of claim 5, wherein the adjustable communication rate is a plurality of communication rates that are set in stages within the predetermined range.

7. The communication system of claim 1, wherein the adjustable communication rate information comprises a plurality of stages of communication rates.

8. The communication system of claim 1, wherein the base station control station determines whether the desired communication rate is adjustable.

9. The communication system according to claim 2, wherein the base station control station includes a loopback means for looping back a response message indicating a failure of the line setup request to a switching center in the core network when it is determined that the line is insufficient and the line setup request message does not contain the adjustable communication rate information.

10. The communication system according to claim 9, wherein the response message contains information indicating that the line is short for which the failure is due.

11. A communication method for a communication system, the communication system comprising: a user terminal including a plurality of base stations (3-1 to 3-4) each having cells (A1 to A4) as wireless service areas; base station control tables (2-1-2); and a core network (1) having a switching function; the communication method comprises the following steps:

sending a request in the user terminal to a switching center in the core network; and

in the core network, when a line setup request message is transmitted to the base station control station after receiving a request from the user terminal (4) in the cell, not only desired communication rate information but also adjustable communication rate information other than the desired communication rate is transmitted thereto.

12. The communication method according to claim 11, comprising the steps of: a judging step of, in the base station control station, judging that the line is insufficient in response to the line setting request message, based on the expected communication rate information and a use state of the line managed by the base station control station; and a deciding step of deciding one of the requested adjustable communication rate information as a communication rate of the communication service in a case where the line is insufficient.

13. The communication method according to claim 12, comprising a step of returning, in the base station control station, the decided communication rate information together with a response message to a switching center in the core network.

14. The communication method according to claim 13, comprising a starting step of starting, in the core network, the communication service based on the communication rate information sent back from the base station control station.

15. The communication method according to any of claims 11-14, wherein the adjustable communication rate is a rate within a predetermined range that is smaller than the desired communication rate.

16. The communication method according to claim 15, wherein the adjustable communication rate is a plurality of communication rates set in stages within the predetermined range.

17. The communication method of claim 11, wherein the adjustable communication rate information comprises a plurality of stages of communication rates.

18. The communication method according to claim 11, wherein the base station control station judges whether the desired communication rate is adjustable.

19. The communication method according to claim 12, comprising a step of returning, in the base station control station, a response message indicating that the line setup request has failed to a switching center in the core network when it is determined that the line is insufficient and the line setup request message does not contain the adjustable communication rate information.

20. The communication method according to claim 19, wherein the response message contains information indicating that the line is short for which the failure is due.

21. A switching center in a core network having a switching function in a communication system, the communication system comprising: a plurality of base stations (3-1 to 3-4) each having cells (A1 to A4) as wireless service areas; and a base station control station (2-1, 2-2); and a switching center in a core network having a switching function; the switching center in the core network comprises,

and a transmitting device for responding to a call accompanying a communication service type from a user terminal existing in the cell, and for transmitting desired communication rate information corresponding to the call communication service type and adjustable communication rate information other than the desired communication rate to the base station controller when transmitting a line setup request message to the base station controller.

22. The switching center of claim 21, wherein the adjustable communication rate information includes a plurality of stages of communication rates.

23. A base station control station (2-1, 2-2) in a communication system, the communication system comprising: a plurality of base stations (3-1 to 3-4) each having cells (A1 to A4) as wireless service areas; a base station control console (2-1, 2-2); and a switching centre (1) in the core network having a switching function; the base station control station includes:

and a receiving device for receiving, in response to a call accompanying a communication service type from a user terminal existing in the cell, desired communication rate information corresponding to the call communication service type included in the line setup request message transmitted from the switching center and adjustable communication rate information other than the desired communication rate.

24. The base station control console according to claim 23, further comprising:

a judging device, which is used for judging the shortage of the line according to the expected communication rate information and the using state of the line managed by the base station console; and

and a determining unit configured to determine one of the adjustable communication rate information as a communication rate of the communication service in a case where a line is insufficient.

25. The base station control station according to claim 24, further comprising a loopback means for looping back the decided communication rate information together with a response message to a switching center in the core network.

26. The base station control station according to claim 24 or 25, wherein the adjustable communication rate is a rate smaller than the desired communication rate within a predetermined range.

27. The base station control station according to claim 25, wherein the adjustable communication rate is a plurality of communication rates set in stages within a prescribed range.

28. The base station control station according to claim 24, comprising returning means for returning a response message indicating that the line setup request has failed to a switching center in the core network when it is determined that the line is insufficient and the line setup request message does not contain the adjustable communication rate information.

29. The base station control station according to claim 28, wherein the response message contains information indicating that the line is short for which the failure is due.

30. The base station console as claimed in claim 23, wherein the adjustable communication rate information includes communication rates of a plurality of stages.