Abstract:
Disclosed are an apparatus and a method for managing radio resources, capable of effectively managing radio resources. When a normal call and a handover call are attempted, radio resources are allocated and it is determined whether or not to perform an overload control based on received load related information and then it is determined whether or not to admit the call depending on an availability of a bandwidth for radio resources, a priority of real time traffic or a locking probability of data. The quality and efficiency of a mobile communication service is enhanced by pertaining an effective allocation on radio resources and controlling the load of radio resources in the mobile communication system. The radio resource managing apparatus and method using the same are applied to IMT (International Mobile Telecommunications)-Advanced system base station, thereby optimizing the efficiency of radio resources.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2008-0128532, filed on Dec. 17, 2008, the disclosure of which is incorporated by reference in its entirety for all purposes. 
     BACKGROUND 
     1. Field 
     The following description relates to a radio resource management technology in a mobile communication system, capable of effectively allocating radio resources while managing the radio resources when a normal call or a handover call is attempted. 
     2. Description of the Related Art 
     Currently, the 3 rd  Generation Partnership Project (3GPP) mobile communication system is currently competitive due to a superior down link capacity and uplink capacity through a High-Speed Downlink Packet Access (HSDPA). However, in order to provide a mobile communication system capable of being competitive in a quickly developing information communication based society, a new wireless access technology needs to be developed. 
     In order for the existing 3GPP related technologies to be competitive in the future, a wireless access technology for a next generation mobile communication system needs to be considered as an important issue. Main issues of a next generation mobile communication system IMT (International Mobile Telecommunications)-Advanced include reduced latency, higher user data rates, improved system capacity and coverage, and reduced cost for network providers. 
     In addition, the next generation mobile communication system is working on an interoperation and a handover with respect to non-3G families such as a WLAN in addition to an interoperation with respect to 3G families. Further, a next generation mobile terminal needs to simultaneously support WLAN and 3G families. 
     In order to strengthen the competitiveness of such a next generation mobile communication system, radio resource management needs to be effectively performed. In general, the conventional radio resource management is performed regardless of various characteristics of the next mobile communication system and thus the efficiency in use of the radio resources is lowered. 
     The conventional radio resource management provides the same priority to all of calls regardless of the characteristics of services, and is performed based on reception signal intensity or a speed of a mobile terminal. In such a case, a predetermined radio resource, which exerts the greatest influence on the performance of the mobile communication system is not effectively used, and thus the system performance is extremely hindered. In this regard, studies have been pursued on various kinds of theories such as buffer, priority, fuzzy theory, etc. to achieve efficient radio resource management. However, some of such theories are too simple to enhance the efficiency in management of radio resources, whereas, for example, a radio resource management algorithm based on the fuzzy theory is too complicated, which increases the cost for implementing the radio resource management algorithm. Accordingly, the fuzzy theory can not be applied to a commercial mobile communication system. 
     SUMMARY 
     Accordingly, in one aspect, there is provided an apparatus and a method for managing radio resources, capable of enhancing the quality and efficiency of a mobile communication service by performing an effective allocation on radio resources and controlling the load of radio resources in the mobile communication system. In detail, when a normal call and a handover call are attempted, radio resources are allocated and it is determined whether or not to perform an overload control based on received load related information and then it is determined whether or not to admit the call depending on an availability of a bandwidth for radio resources, a priority of real time traffic or a locking probability of data. 
     In one general aspect, there is provided a radio resource managing apparatus for receiving a normal call request or a handover call request and managing radio resources for processing the normal call request or the handover call request and in a mobile communication system. The radio resource managing apparatus includes a call admission controller to determine whether or not to admit the normal call request or the handover call request depending on whether a Quality of Service (QoS) is guaranteed, traffic is real time traffic, or locking of traffic is possible; and a load controller to allocate the radio resources in response to the normal call request or the handover call request while checking spare radio resources and to provide the call admission controller with information indicating allocable radio resources. 
     The call admission controller receives the normal call request or the handover call request, transmits the normal call request or the handover call request to the load controller and estimates whether the QoS is guaranteed based on the information indicating the allocable radio resources. 
     If the QoS is guaranteed, the call admission controller admits the normal call or the handover call, and if the QoS is not guaranteed, the call admission controller determines whether the traffic is real time traffic. If the traffic is real time traffic, the call admission controller requests the load controller to allocate radio resources and estimates whether QoS is guaranteed. If the QoS is guaranteed, the call admission controller admits the normal call or the handover call, and if the QoS is not guaranteed, determines whether traffic locking is possible. If the traffic locking is possible, the call admission controller requests the load controller to allocate radio resources capable of guaranteeing a minimum level of QoS, thereby admitting the normal call or the handover call. 
     In another general aspect, there is provided a method of managing radio resources in a mobile communication system including a load controller, which allocates the radio resources upon a normal call request or a handover call request and determines whether or not to perform an overload control by using received load relating information, and a call admission controller determining whether or not to admit the normal call request or the handover call request depending on whether a Quality of Service (QoS) is guaranteed on the radio resources allocated by the load controller, traffic is real time traffic and traffic locking is possible. The radio resource managing method is performed as follows. First, if the call admission controller transmits the normal call request or the handover call request to the load controller, the load controller checks spare radio resources and providing information about allocable radio resources to the call admission controller. After that, the call admission controller estimates whether the QoS is guaranteed on the allocable radio resources, wherein if the QoS is guaranteed, the call admission controller admits the normal call or the handover call, and if the QoS is not guaranteed, the call admission controller determines whether the traffic is real time traffic. Then, if the traffic is real time traffic, the call admission controller requests the load controller to allocate radio resources. The load controller checks spare radio resources to provide information about allocable radio resources to the call admission controller. Then, the call admission controller estimates whether QoS is guaranteed based on the allocable radio resources. Then, if the QoS is guaranteed, the call admission controller admits the normal call or the handover call, and if the QoS is not guaranteed, the call admission controller determines whether locking is possible. Finally, if the locking is possible, the call admission controller requests the load controller to allocate radios resources capable of guaranteeing a minimum level of QoS, the load controller allocates the requested radio resources to provide information about the requested radio resources to the call admission controller, and the call admission controller admits the normal call or the handover call based on the information. 
     When the call admission controller processes the normal call request, the determining of the locking probability includes determining whether locking of non-real time traffic is possible. When the call admission controller processes the handover call request, the determining of the locking probability includes determining whether locking of real-time traffic or non-real time traffic is possible. 
     Other objects, features and advantages will be apparent from the following description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating an exemplary radio resource management apparatus; 
         FIG. 2  is a view illustrating an exemplary radio resource management method; and 
         FIG. 3  is a view illustrating another exemplary radio resource management method. 
     
    
    
     Elements, features, and structures are denoted by the same reference numerals throughout the drawings and the detailed description, and the size and proportions of some elements may be exaggerated in the drawings for clarity and convenience. 
     DETAILED DESCRIPTION 
     The detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses and/or systems described herein. Various changes, modifications, and equivalents of the systems, apparatuses, and/or methods described herein will likely suggest themselves to those of ordinary skill in the art. Also, descriptions of well-known functions and constructions are omitted to increase clarity and conciseness. 
       FIG. 1  is a view illustrating an exemplary radio resource management apparatus. 
     As shown in  FIG. 1 , a radio resource management apparatus includes a call processor  101  and a resource manager  102 . The resource manager  102  includes a call admission controller  201  and a load controller  202 . 
     The call processor  101  controls a normal call or a handover call of a wireless area by controlling a radio signaling protocol. To this end, the call processor  101  is provided with a normal call processor  301  and a handover call processor  302 . 
     The call admission controller  201  determines whether or not to admit a normal call or a handover call requested upon a normal call attempt or a handover call attempt. The load controller  202  allocates radio resources and determines whether or not to perform an overload control based on received load related information. 
     For example, if the call admission controller  201  receives a call request from the call processor  101  and transmits the call request to the load controller  202 , the load controller  202  checks spare radio resources to provide the call admission controller  201  with information about allocable radio resources. The call admission controller  201  admits or rejects the call request by determining whether QoS is guaranteed, traffic is real time traffic and locking is possible based on the information provided from the load controller  202 . The locking represents a process of finding a condition ensuring a minimum level of QoS while temporally delaying a service. 
     The load controller  202  includes an overload controller  401  performing an overload control when the amount of collected load exceeds a predetermined critical value, a load monitor  402  to monitor load of downlink or uplink and deliver load information obtained by the monitoring to the overload controller  401 , a resource allocator  403  allocating radio resources and maintaining spare radio resources, and a resource status DB  404  storing various kinds of information on a resource status. 
     Various kinds of parameters are used to perform a load control operation. The parameters are set as values for optimizing the performance of a system while maintaining a static state or a dynamic state. To this end, a scheme of deriving load controlling parameters suitable for various conditions and applying desirable values to the parameters is required. The load controller  202  performs a load control operation based on values acquired through the load monitor  402  while preventing the quality of the service on real time traffic and non-real time traffic from being lowered. That is, if a load exceeds a predetermined critical value, the load controller  202  performs a load control operation based on received load relating values. In addition, if the load is of a normal level, the load controller  202  continually monitors a corresponding system. 
     The load controller  202  allocates radio resources to calls in connection with the call admission controller  201 . The load controller  202  continually updates the amount of occupied resources, and allocates available resources within a range of spare resources. That is, the load controller  202  maintains or manages available resources through an interface with respect to the call admission controller  201  such that radio resources are allocated upon a call request or a handover call attempt. 
     The resource status DB  404  performs maintenance/management on the amount of entire resources, the amount of resources being used and the amount of available resources at each base station of cells. That is, the resource status DB  404  performs maintenance/management on the status of overall resources for each base station. The resource status DB  404  manages and maintains a status of resources in a system while a new call is generated and then fades. 
       FIG. 2  is a view illustrating an exemplary radio resource management method, in which the exemplary radio resource managing apparatus described above receives a normal call request and then processes the call request while managing radio resources based on the call request. 
     First, if the normal call processor  301  receives a call attempt request from a mobile terminal, the normal call processor  301  requests the call admission controller  201  to admit a call by using a call type, a call service classification and QoS as parameters such that an access for a wireless area is set (operation  101 ). 
     The call admission controller  201  transmits the call admission request to the load controller  202 , thereby requesting a resource allocation (operation  102 ). 
     The load controller  202  checks a status of spare radio resources in response to the call admission request (operation  103 ), and provides the call admission controller  201  with information on allocable radio resources (operation  104 ). For example, the load controller  202  provides the call admission controller  201  with information on a bandwidth available for the resource status. 
     The call admission controller  201  determines whether QoS is guaranteed based on the information transmitted from the load controller  202  (operation  105 ). For example, the call admission controller  201  determines whether the bandwidth is suitable for the present resource status. 
     Upon the result of determination on the QoS, if the QoS is guaranteed, the call admission controller  201  reports a call admission to the normal call processor  301  (operation  106 ), and if the QoS is not guaranteed, the call admission controller  201  determines whether the traffic is real time traffic (operation  107 ). 
     If the traffic is not real time traffic, the call admission controller  201  reports a call rejection to the normal call processor  301  (operation  108 ). If the traffic is real time traffic, which is sensitive to a time delay, the call admission controller  201  requests the load controller  202  to reallocate radio resources (operation  109 ). 
     The load controller  202  checks a status of spare radio resources (operation  110 ), and provides the call admission controller  201  with information on allocable radio resources (operation  111 ). 
     The call admission controller  201  determines whether QoS is guaranteed based on the information on the reallocated radio resources received from the load controller  202  (operation  112 ). 
     Upon the result of determination on the QoS, if the QoS is guaranteed, the call admission controller  201  reports a call admission to the normal call processor  301  (operation  113 ), and if the QoS is not guaranteed, it is determined whether locking is possible (operation  114 ). The locking represents a process of finding a condition ensuring a minimum level of QoS while temporally delaying a service. For example, the call admission controller  201  determines whether the locking of non-real time traffic is possible. If the locking is not possible, the call admission controller  201  reports a call rejection to the normal call processor  301  (operation  116 ). If the locking is possible, the call admission controller  201  transmits a request for radio resources guaranteeing a minimum level of QoS to the load controller  202  (operation  115 ). 
     The load controller  202  checks spare radio resources in response to the request (operation  117 ), and provides the call admission controller  201  with information on allocable radio resources (operation  118 ). As a result, the call admission controller  201  reports a call admission to the normal call processor  301  (operation  119 ). 
       FIG. 3  is a view illustrating another exemplary radio resource management method, in which the exemplary radio resource managing apparatus receives the handover call request and processes the handover call while managing radio resources in response to the handover call request. 
     First, if the handover call processor  302  receives a call attempt request from a mobile terminal, the handover call processor  301  requests the call admission controller  201  to admit a call by using a call type, a call service classification and QoS as parameters such that an access for a wireless area is set (operation  201 ). 
     The call admission controller  201  transmits the call admission request to the load controller  202  to request a resource allocation (operation  202 ). 
     The load controller  202  checks a status of spare radio resources in response to the call admission request (operation  203 ), and provides the call admission controller  201  with information on allocable radio resources (operation  204 ). For example, the load controller  202  provides the call admission controller  201  with information on a bandwidth available for the resource status. 
     The call admission controller  201  determines whether QoS is guaranteed based on the information transmitted from the load controller  202  (operation  205 ). For example, the call admission controller  201  determines the bandwidth is suitable for the present resource status. 
     Upon the result of determination on the QoS, if the QoS is guaranteed, the call admission controller  201  reports a call admission to the handover call processor  302  (operation  206 ), and if the QoS is not guaranteed, the call admission controller  201  determines whether the traffic is real time traffic (operation  207 ). 
     If the traffic is not real time traffic, the call admission controller  201  reports a call rejection to the handover call processor  302  (operation  208 ). If the traffic is real time traffic, which is sensitive to a time delay, the call admission controller  201  requests the load controller  202  to reallocate radio resources (operation  209 ). 
     The load controller  202  checks a status of spare radio resources (operation  210 ), and provides the call admission controller  201  with information on allocable radio resources (operation  211 ). 
     The call admission controller  201  determines whether QoS is guaranteed based on the information on the reallocated radio resources received from the load controller  202  (operation  212 ). 
     Upon the result of determination on the QoS, if the QoS is guaranteed, the call admission controller  201  reports a call admission to the handover call processor  302  (operation  213 ), and if the QoS is not guaranteed, it is determined whether locking is possible (operations  214  and  216 ). Locking represents a process of finding a condition ensuring a minimum level of QoS while temporally delaying a service. In the case of a handover call, locking of real time traffic may be performed. Accordingly, the locking probability is estimated on both the real time traffic and the non-real time traffic. 
     That is, it is determined whether locking of real time traffic is possible (operation  214 ). If the locking of the real time traffic is possible, the call admission controller  201  requests the load controller  202  to allocate radio resources capable of guaranteeing a minimum level of QoS (operation  215 ). If the locking of the real time traffic is not possible, it is determined whether locking of non-real time traffic is possible (operation  216 ). If the locking of the non-real time traffic is possible, the call admission controller  201  requests the load controller  202  to allocate radio resources capable of guaranteeing a minimum level of QoS (operation  217 ). If the QoS of the handover call is not guaranteed and the locking of the both traffic is not possible, the call admission controller  201  reports a call rejection to the handover processor  302  (operation  208 ). 
     If the locking of the real time traffic or the non-real time traffic is possible, the load controller  202  checks spare radio resources (operation  219 ), allocates radio resources capable of guaranteeing a minimum level of QoS and provides the call admission controller  201  with information on the allocated radio resources (operation  220 ). The call admission controller  201  reports a call admission to the handover call processor  302  (operation  221 ). 
     Since a handover call is more sensitive to service quality as compared with a normal call, the handover call can be provided to a real time service, such as voice or video, and a service insensitive to a time delay, such as e-mail and a web service. In this case, the real time services need to be processed with higher priority. However, if the real time service is not admitted, spare radio resources are allocated to the non-real time services, thereby guaranteeing QoS of a system and improving the performing of the system. 
     The invention can also be embodied as computer readable codes on a computer readable recording medium. The computer readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of the computer readable recording medium include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and carrier waves such as data transmission through the Internet. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. Also, functional programs, codes, and code segments for accomplishing the present invention can be easily construed by programmers skilled in the art to which the present invention pertains. A number of exemplary embodiments have been described above. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Accordingly, other implementations are within the scope of the following claims.