Patent Application
20060052103
This application claims priority from Japanese Patent Application 2004-262524, filed Sep. 9, 2004, the disclosure of which is incorporated herein by reference.
1. Technical Field
The present invention relates to a communication system, a radio base station and a radio network controller and a resource management method.
2. Background Art
A radio access network system comprises a radio base station apparatus (Node B) and a radio network control apparatus (RNC), the radio base station apparatus being connected with a plurality of mobile devices, and the radio base station control apparatus being connected to an upper-level core network which performs line switching and packet switching. In a system having such configuration, when a call setup is performed, resources are consumed in the radio base station apparatus, such as a radio band determined by the number of codes, a symbol rate, etc. in the case of W-CDMA (Wideband-Code Division Multiple Access) are consumed. When priority is provided for a call setup, it is possible to release existing resources in accordance with the priority and to preferentially set up a call with high priority. This function is referred to as a pre-emption function. Next, an example of a conventional pre-emption function is explained.
Japanese Patent Laid-Open No. 2003-209871 shows a urgent call connection method in which, when an urgent call, which is an example of a call that is set high priority level, is sent from a mobile device belonging to a mobile communication system, the urgent call can be connected even if all radio resources of a radio base station are used. In this method, the mobile device in a mobile communication system, when performing handover at the time of making an urgent call or during urgent calling, notifies a switching control station of an urgent call notice message via a radio base station or a radio base station of the handover destination. When all radio resources in the radio base station or in the radio base station of the handover destination are used, the switching control station selects a specific channel from the radio resources used by one of the radio base stations, and, to reduce processing load for the selected specific channel so that free resources for the urgent call are secured, assigns the urgent call to the secured free resources.
Japanese Patent Laid-Open No. 2003-32753 shows a public communication system and a technique for providing a necessary high-speed service for a mobile communications terminal flexibly as required. The public communication system comprises a plurality of communication networks of different service purposes, a plurality of mobile communication terminals communicating with the plurality of communication networks, and a W-CDMA system. The W-CDMA system connects and integrates a plurality of communication networks. Furthermore, the W-CDMA system controls transmission rates at which each of the plurality of mobile communication terminals communicates with the plurality of communication networks, on the basis of priority levels of each of the plurality of mobile communication terminals.
In recent communication networks of movable bodies etc., for example, there has been an increase in the number of cases of handling various calls typified by a multi-call in which a plurality of communications are simultaneously performed by a single mobile device. In addition, there is a case where resources set up in the uplink and those set up in the downlink are different.
A technique for managing resources in accordance with priorities of calls is known in the art. However, a technique for flexibly changing resources in a radio base station apparatus in accordance with the recent various call setups has not yet been disclosed, and it has been desired to maintain and manage resources in the radio base station apparatus effectively and flexibly.
An exemplary object of the present invention is to solve the problem described above and to provide a communication system in which a radio resource assignment can be changed flexibly without releasing all radio resources that have been assigned to a certain radio link in order to establish a new radio link.
A further exemplary object of the present invention is to provide a radio base station apparatus and a resource management method which flexibly changes resources in the radio base station apparatus so as to maintain existing links by changing rates without releasing the existing calls, in the case where resources are consumed due to a new call setup request.
A method according to an exemplary embodiment of the present invention comprises establishing a plurality of radio links between a plurality of mobile devices and a base station. Here, the plurality of mobile devices communicate with the base station via the plurality of radio links. The method further comprises assigning each of the plurality of radio links a plurality of radio resources, selecting at least one radio link from the plurality of radio links based on priority levels that are set for the plurality of radio links, respectively, releasing at least one but not all of the plurality of radio resources from the radio link which is selected, and assigning at least one of the plurality of radio resources which is released to a new radio link which is established.
These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and accompanying drawings, which should not be read to limit the invention in any way, in which:
The described exemplary embodiments are intended to assist in the understanding of the invention and are not intended to limit the scope of the invention in any way.
According to an exemplary embodiment of the present invention, a communication system comprises a radio network controller or a radio network control apparatus, a base station or a base station apparatus and a plurality of mobile devices. The base station establishes a plurality of radio links between the base station and the plurality of mobile devices. The plurality of mobile devices communicate with the base station via the plurality of radio links.
The base station assigns each of the plurality of radio links or calls a plurality of radio resources. That is, each radio link is established based on plural radio resources. For example, the radio resources may be defined in terms of a length of a spreading code, a symbol rate in a Code Division Multiple Access (CDMA) network. Furthermore, radio resource may be defined in terms of any other parameter as would be understood in the art that may be utilized to define the radio resource. The necessary number of resources for establishing a radio link may be determined corresponding to a spreading factor for the radio link or any other parameter as would be understood in the art.
When establishing a new radio link, the base station selects at least one radio link from the plurality of radio links based on priority levels that are set for the plurality of radio links. The base station may select at least one radio link with a lower priority than a priority level to be set for the new radio link in order to change the assignment of the radio resources to the plurality of radio link. The priority level to be set for the new radio link may be included in a message, which instructs the base station to establish the new radio link, transmitted from the network controller and received by the base station.
Furthermore, each of the radio resources may be associated with information about whether it is subject to being released from at least one radio resource. Accordingly, the base station may select a radio resource that is subject to being released from at least one radio resource and has a lower priority level than the priority level to be set for the new radio link.
Subsequently, the base station releases at least one but not all radio resources from the chosen radio link. The base station may release radio resources from plural radio links. For example, in a case where the base station chose a first radio link and a second radio link, the base station may release all radio resources except the minimum number of radio resources from the first radio link and releases at least one but not all radio resources from the second radio link. The minimum number of radio resources may be determined in advance as a parameter in the communication network.
Finally, the base station assigns the released radio resource to the new radio link.
Here, the base station may start changing the radio resource assignment in a case where a total number of necessary resources for establishing the new radio link and the plurality of resources assigned to the plurality radio links that have been established is larger than the maximum number of radio resources for the base station. Information regarding the number of the necessary radio resources for establishing the new radio link may be included in the message from the radio network controller. Furthermore, the information regarding the necessary number may be a spreading factor for the new radio link, where the new radio link is established based on a CDMA technique. Also, the information may be any other information as would be understood in the art that may show the number of necessary radio resources. In addition, the base station may select at least one radio link from the plurality of radio links if the new radio link is subject to being established by releasing at least one radio resource which is assigned to a radio link other than the new radio link. Information about whether the new radio link is subject to being established by releasing at least one radio resource which is assigned to a radio link other than the new radio link may be included in the message from the radio network controller.
Accordingly, a radio resource assignment may be changed flexibly without releasing all radio resources that have been assigned to a certain radio link in order to establish a new radio link.
According to another exemplary embodiment, the base station transmits a second massage indicating that a change is necessary in the radio resource assignment to the plurality of radio links in order to establish the new radio link, after receiving, from the radio network controller, the message instructing the base station to establish the new radio link. The radio network controller receives the second message. In response to the second message, the network controller transmits a third message instructing the base station to change the radio resource assignment as described above with regard to the base station.
Accordingly, a radio resource assignment may be changed flexibly without releasing all radio resources that have been assigned to a certain radio link in order to establish a new radio link.
According to a further exemplary embodiment of the invention a resource management method is a method in which a radio base station apparatus connected with a radio network control apparatus may manage resources of users. In this method, when securing resources for a new call or a new radio link setup request, resources of existing users may be managed in accordance with a priority so as to enable links of existing users to be maintained and a part of resources corresponding to the links to be released.
A resource management method according to another exemplary embodiment of the present invention is a method in which a radio base station apparatus connected with a radio network control apparatus may manage resources of users. The method may comprise the steps of: receiving a setup message for a new call setup request from the radio network control apparatus; determining whether or not there are free resources of existing users for performing the call setup; and determining whether or not the setup message is a message to preferentially secure resources for the call setup by maintaining links of the existing users and by releasing a part of resources corresponding to the links. The method also may comprise the steps of: in the case where there is no idle portion in the resources of existing users and the setup message is a message to preferentially secure resources, searching in the order of ascending priority level for existing users whose priority levels are lower than that of the setup message and whose resources can be changed; and in the case where a total of the resources of existing users whose resources can be changed exceeds resources required for performing the call setup as a result of the search, releasing all or a part of the resources of existing users and securing new resources for the call setup.
In the resource management method, the resources may be managed for each user in terms of an uplink signal from a mobile device connected with the radio base station apparatus to the radio base station apparatus and to a downlink signal from the radio base station apparatus to the mobile device, respectively.
In the resource management method, the number of resources may be defined corresponding to spreading factors.
In the resource management method, the setup message may include at least user identification information for identifying a mobile device of a call setup object, resource information desired at the time of setting up a link of the mobile device connected to the radio base station apparatus, and priority information with respect to existing users.
In the resource management method, the setup message may further include information regarding indication of whether the priority information is effective or ineffective.
In the resource management method, the setup message preferably includes for each of plural individual channels the priority information and the information regarding indication of whether the priority information is effective or ineffective.
A radio base station apparatus according to an exemplary embodiment of the present invention may comprise a transceiver section which transmits and receives a message relating to a call setup request to and from a radio network control apparatus, and a user management table for managing resources of users. The radio base station apparatus may further comprise a control section performing control, which determines whether or not there is an idle portion in resources of existing users in order to perform the call setup with reference to the user management table, in the case where a setup message for a new call setup request is received. The control section determines whether or not the setup message is a message to preferentially secure resources for the call setup by maintaining links of the existing users and by releasing a part of the resources corresponding to the links. Further, the control section searches in the order of ascending priority level for the existing users whose priority level are lower than that specified by the setup message and whose resources can be changed, in the case where there is no idle portion in the resources of existing users and the setup message is a message to preferentially secure resources. The control section releases all or a part of the resources of existing users and secures new resources for the call setup, in the case where a total of the resources of existing users whose resources can be changed exceeds resources required for performing the call setup as a result of the search.
In the radio base station apparatus, the user management table may include priority level of user links which are managed for each user, resources in an uplink, and resources in a downlink.
In the radio base station apparatus, the number of resources may be defined corresponding to spreading factors.
In radio base station apparatus, the user management table may further include information about whether the priority information is effective or ineffective.
In radio base station apparatus, the user management table may further include for each of plural individual channels the priority level information and the information about whether the priority level information is effective or ineffective.
In radio base station apparatus, a radio access network system may comprise the radio base station apparatus and the radio network control apparatus.
Exemplary embodiments of the invention are described below with reference to the attached figures. The described exemplary embodiments are intended to assist in the understanding of the invention and are not intended to limit the scope of the invention in any way.
The radio base station apparatus 20 comprises a message transceiver section 21 which performs transmission and reception of a message to and from the radio network control apparatus 10, a mobile device processing section 22 which is connected with a plurality of mobile devices and which performs control processing of radio transmission and reception, a user management table 23 for managing resources of mobile devices (users), a SF (spreading factor)/resource comparison table 24 for comparing spreading factors and resources. Furthermore, the base station apparatus 20 comprises a control section 25 which controls the radio base station apparatus 20. For example, the control section 25 performs a resource management as described later in detail. The control section 25 may comprise a CPU, a memory and/or any other circuit as would be understood in the art. Although the mobile device processing section 22 in the radio base station apparatus 20 has various functions for effecting connection with mobile devices, the functions are not concerned with the exemplary embodiment of present invention and hence the explanation thereof will be omitted. A communication sequence between the radio network control apparatus 10 and the radio base station apparatus 20 in the case where a new call setup is generated will be described below.
The radio base station apparatus 20 calculates the number of resources required for the setup with reference to spreading factor information in the setup message received via the message transceiver section 21. In the case where a total number of the calculated number of resources and the number of existing resources exceeds the maximum number of resources in the radio base station apparatus and a new call setup can therefore not be achieved, the radio base station apparatus 20, which selects users as users corresponding to the pre-emption with priority levels lower than that of the user to be set up with reference to the user management table 23, calculates SF change values of users corresponding to the pre-emption so as to make it possible to set up the number of resources required for assigning the user to be set up. Subsequently, the base station apparatus 20 transmits a pre-emption required indication to the radio network control apparatus 10 via the message transceiver section 21 (step S12).
The radio network control apparatus 10 which has received the pre-emption required indication determines a possible rate change pattern on the basis of the indicated SFs, and transmits a rate change message to the radio base station apparatus 20 via the message transceiver section 11 (step S13). The radio base station apparatus 20, which secures free resources by this rate change, returns an OK response to the rate change message via the message transceiver section 21 (step S14), and further returns an OK response to the setup message (step S15).
As described above, in the management method of call setup with priority level which is performed between the radio network control apparatus 10 and the radio base station apparatus 20, when resources are fully used at the time of setting a bearer with a high priority level in the radio base station apparatus, resources are secured so as to make it possible to setup the radio link with the high priority level, while maintaining links with low priorities for bearers with low priority levels. That is, contrary to existing call setups which are usually subjected to call deletion, the operation is made so as to maintain as many of the existing call setups as possible.
Next, an exemplary embodiment of the radio base station apparatus is more specifically described. In
The priority level may take a value within a fixed range, and here a larger value of the priority level is regarded as a lower priority level and the largest value of the priority level is regarded as no priority level (no operation of the pre-emption function). In the case where all priority levels set for each DchID have no priority level, the setup message is not treated as a message for starting the pre-emption. The Capability which holds two states of ON and OFF, is treated as an Pre-Emption Trigger Message for starting the pre-emption in the ON state, and is not treated as the Pre-Emption-Trigger Message in the OFF state. The Vulnerability also has two states of ON and OFF. The user associated with the message with the ON state of Vulnerability is subject to the pre-emption. That is, even after a radio link is established for the user, its SF can be changed by rate change in the pre-emption procedure. On the other hand, a user associated with the message with the OFF state of Vulnerability is not subject to the pre-emption. Also, in the case where one of the Capability and the Vulnerability is in the ON state, an effective priority level value may be surely set and the maximum priority level value (=no priority level) may not be set.
Next, an operation of the present exemplary embodiment is described with reference to
On the other hand, in the case where resources are fully used or a radio link or a call associated with the setup message cannot be established within the maximum number of resources (Y in step S21) and the setup message is not a message of pre-emption object (for example, Capability=OFF), the setup message is returned with NG to the radio network control apparatus 10 (step S30), and a series of operations are ended.
In the case where resources are fully used or a radio link or a call associated with the setup message cannot be established within the maximum number of resources and the setup message is a message of pre-emption object (Y in step S22), the radio base station apparatus 20 searches resources of existing users in the user management table 23 (step S23). In the case where there is no relevant user (N in step S23), the setup message is returned with NG to the radio network control apparatus 10 (step S30), and a series of operations are ended.
On the other hand, in the case where there exists a relevant user, i.e. in the case where there exists a user having priority level lower than that of the user associated with the setup message and having SF which can be changed, and where the SF required by the setup message (Y in step S23) can be assigned to the call or radio link by changing the SF of the existing users, the pre-emption required indication shown in
The radio network control apparatus 10 receives the pre-emption required indication shown in
The radio base station apparatus 20 receives the rate change message, changes assignment of existing resources (step S26) in accordance with the change in SF, and transmits a rate change message response to the radio network control apparatus 10 after securing free resources for establishing the radio link or the call associated with the setup massage (step S27).
The radio base station apparatus 20 which has already received the setup message to start the pre-emption, assigns resources released by the rate change to the radio link or the call associated with the setup massage and update the user management table (step S28). Subsequently, the radio base station apparatus 20 returns the setup message with OK to the radio network control apparatus 10 (step S29) to end a series of operations.
Next, details of the step S23 in
In step S44, the base station apparatus 10 determines whether or not SFs assigned to the user searched in the step S43 can be changed. In the case of a bearer with SFs which can not be changed (when the number of resources assigned to the bearer is already a minimum value, etc.), the process proceeds to step S47, and in the case of a bearer with SFs which can be changed, the process proceeds to step S45. In step S45, new resources produced for the user associated with the setup message by changing SFs are added together. In step S46, the base station determines whether or not the resources added together exceed predetermined resources required by the setup message. When the resources added together exceed the predetermined resources, the process proceeds to step S24, and when the resources added together are less than the predetermined resources, the process proceeds to step S47.
In step S47, the priority level of the user to be searched is raised by one level in order to expand objects to be searched (to include users with lower priority level in objects to be searched), and then the process returns to step S41.
Next, a more specific example is described with reference to the user management table.
As shown in table 23a, it is assumed that there exists a user with user ID=1, DL resource=1, priority level=2, a user with user ID=2, DL resource=2, priority level=3, a user with user ID=3, DL resource=16, priority level=4, a user with user ID=4, DL resource=2, priority level=5, and a user with user ID=5, DL resource=8, priority level=5. In this case, a setup message is assumed to have user ID=6, DLSF=8 (corresponding to DL resource=16 with reference to
Since a total of existing DL resources is 29, the remainder obtained by subtracting the total from the maximum number of resources becomes 1=30−29. First, at most seven DL resources are reduced from the user with user ID=5 and with the lowest priority level resulting in the minimum number of resources (i.e., one resource) assigned to the user with user ID=5. Next, resources of the user with user ID=4 is made to be reduced, but is unable to be reduced because the Vulnerability is OFF. Further, eight DL resources is reduced from the user with user ID=3 and with lower priority level than that of the user associated with the setup message. As a result, a total of sixteen DL resources can be obtained. With the obtained DL resources, DL resources=16 corresponding to DLSF=8 (see
In this way, resources are successively secured from users with low priority level and with SFs which can be changed, and when resources required by the setup message to be processed can be secured, OK is returned in response to the setup message, while the user is added to the user management table and a new user management table 23b is made. In the above described example, the minimum number of resource to be left is assumed to be one when the number of resources of existing users is reduced, but the minimum number of resource may be two or more in order to maintain a call setup of multi-call, as in the case shown in
Next, a second exemplary embodiment according to the present invention is described with reference to
In the case of the second exemplary embodiment, the radio network control apparatus 10 need only transmit the deletion message in accordance with DchID specified by the radio base station apparatus 20, and need not particularly perform bearer selection or determining a possible SF pattern (i.e., information which expected in a massage described in
According to the present exemplary embodiment, the pre-emption function makes it possible to maintain as many links as possible, resulting in resources of existing users being maintained and managed effectively and flexibly.
Furthermore, by releasing resources by a unit of transport channel, call connections using a transport channel other than the released transport channel can be simply maintained even after the pre-emption applies to a user of the call connections.
Although the exemplary embodiments of the present invention have been described above, it will be understood by those skilled in the art that the present invention should not be limited to the described exemplary embodiment, but various changes and modifications can be made within the spirit and the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 262524/2004 | Sep 2004 | JP | national |
