Abstract:
Improved systems and techniques for controlling access to network resources. A base station broadcasts extended access barring (EAB) and access class barring (ACB) information. Upon a determination by a user equipment that the user equipment requires service from the base station, the user equipment determines its EAB category and call type. The user equipment receives the EAB and ACB information broadcast by the base station and determines if it is subject to EAB based on its EAB category. If the user equipment is not subject to EAB, the user equipment determines if its call type is subject to ACB and, if the call type is subject to ACB, applies access class barring based on its call type.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to wireless communication. More particularly, the invention relates to systems and techniques for managing load on a wireless network. 
       BACKGROUND 
       [0002]    One of the greatest problems facing wireless network operators is the need to serve large numbers of customers with varying needs using the infrastructure available to them. Operators of wireless networks and, indeed, most systems serving large numbers of customers, have long observed that loads nearing or exceeding the capacity of a network typically result not from the average demand presented by the users, but from peak demand resulting from simultaneous requests for service from a relatively large proportion of their user population. 
         [0003]    Wireless networks use a number of techniques to manage their peak loads, and one mechanism that can be used as the danger of congestion increases is the temporary denial of service to various users. A base station, such as an eNodeB may broadcast signals indicating that particular users are to be excluded from making connection request. For example, the 3GPP defines standards for access class barring (ACB), in which each UE is a member of one or more access classes and User equipments (UEs) may be configured to recognize data broadcast by an eNodeB excluding their access class. 3GPP technical specification 22.011 V10.3.0 recognizes 16 access classes. Every UE is a member of one of the classes 0-9, and the classes 11-15 are reserved for UEs belonging to special categories, such as public utilities or emergency service providers. Each UE belonging to the classes 11-15 is also a member of one of the classes 0-9. 
         [0004]    When the network needs to control the number of UEs accessing the network, it broadcasts a message indicating the current barring rate commonly applicable for classes 0-9 and a flag designating barred or unbarred status for each of classes 11-15. When a UE in one of classes 0-9 needs access to the network, it draws a random number and compares it to the current barring rate. An access attempt is allowed or not based on the comparison. If the access attempt is not allowed, further attempts are barred for a time period that is calculated based on the mean duration of access control provided by the network and the random number drawn by the UE. 
         [0005]    The 3G Partnership Project is also discussing Extended Access Barring (EAB), which would exclude devices subject to EAB under circumstances in which other devices would be unaffected, or for timer periods longer than those applicable to devices subject to ACB. 
         [0006]    Substantial numbers of devices that are more or less delay tolerant exist in the service areas of wireless networks. A relatively new class of users, that is, machine type communication (MTC) devices, exist in large numbers throughout the service areas of wireless networks. Many MTC devices monitor significant events such as earthquakes or other natural disasters, and the occurrence of such an event is likely to trigger activity by a great many MTC devices, which will record data and transmit the data to a host. Earthquake monitoring devices, for example, might detect and record earthquake forces and then request network service to transmit the data to a host, with the host eventually performing analysis of the data received from MTC devices distributed throughout the region affected by the earthquake. Such MTC devices typically require service for a short duration and most may not actually need service at the exact time the event occurs. However, it is also true that MTC devices do not have awareness of other demands on the network and the communication necessary to give them that information would impose an unnecessary load on the network. 
         [0007]    Many events that would trigger requests for service by MTC devices would also give rise to more urgent demands for service, such as by emergency responders and persons requiring assistance. Network operators wish to insure that service will be available to persons having urgent need and, indeed, to ordinary non-urgent usage to the extent possible, without needing to contend with an excessive load caused by the sudden requests for service of possibly huge numbers of MTC devices seeking to upload data to a host, particularly when the devices do not even need to upload their data at any particular time. 
         [0008]    Therefore, protocols for relatively extended denial of service are being developed. The 3GPP has agreed that if the core network (CN) is overloaded, an eNodeB associated with the core network can set an extended wait timer based on a “delay tolerant access” parameter of the RRC establishment cause, so that a UE that is to be subjected to an extended wait time, such as a delay tolerant UE, may be barred from access reattempts for a longer time period than is typical in the case of ordinary access class barring. Such a delay period may be, for example, up to 30 minutes. 
         [0009]    Discussions are underway for the development of protocols for such extended denial of service. Such protocols are being referred to as extended access barring, or EAB. 
         [0010]    According to 3GPP technical specification (TS) 22.011 v10.3, EAB has the following requirements:
   A network may broadcast EAB information.   EAB information shall define whether EAB applies to UEs within one of the following categories:
       a) UEs that are configured for EAB;   b) UEs that are configured for EAB and are neither in their HPLMN nor in a PLMN that is equivalent to it;   c) UEs that are configured for EAB and are neither in the PLMN listed as most preferred PLMN of the country where the UE is roaming in the operator-defined PLMN selector list on the SIM/USIM, nor in their HPLMN nor in a PLMN that is equivalent to their HPLMN   
       If a UE that is configured for EAB initiates an emergency call or is a member of an Access Class in the range 11-15 and according to clause 4.3.1 that Access Class is permitted by the network, then the UE shall ignore any EAB information that is broadcast by the network.   A UE configured for EAB shall use its allocated Access Class(es), as defined in sub-clause 4.2, when evaluating the EAB information that is broadcast by the network, in order to determine if its access to the network is barred.   If the network is not broadcasting the EAB information, the UE shall be subject to access barring as described in clause 4.3.1   If the EAB information that is broadcast by the network does not bar the UE, the UE shall be subject to access barring as described in clause 4.3.1.   
 
         [0020]    If the UE will not be subject to EAB, the UE should apply normal access class barring based on its access class. In addition, if no EAB information is being broadcast, such as on the broadcast control channel (BCCH), the UE should apply normal access class barring. 
         [0021]    Access class is applied based on the call type in evolved UMTS terrestrial radio access network (E-UTRAN) or on the RRC establishment cause in UTRAN. In E-UTRAN, the non-access stratum (NAS) indicates the call type and the RRC establishment cause to the access stratum (AS), and in UTRAN, the NAS indicates the RRC establishment cause to the AS. 
         [0022]    The interface between the NAS and the AS is a UE internal interface, and standardized mapping is applied between a specific NAS signalling procedure. The call type and RRC establishment provided by NAS to the AS is standardized in normative annexes in 3GPP technical specifications 24.301 (Annex D) and 24.008 (Annex L). The following is an example extracted from Annex D. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE D.1.1: 
               
             
             
               
                   
               
               
                 Mapping of NAS procedure to establishment cause and call type 
               
             
          
           
               
                 NAS 
                   
                   
               
               
                 proce- 
                 RRC establishment cause 
               
               
                 dure 
                 (according 3GPP TS 36.331 [22]) 
                 Call type 
               
               
                   
               
               
                 Attach 
                 If an ATTACH REQUEST has EPS attach type 
                 “originating 
               
               
                   
                 not set to “EPS emergency attach”, the RRC 
                 signalling” 
               
               
                   
                 establishment cause shall be set to MO 
               
               
                   
                 signalling except when the UE initiates attach 
               
               
                   
                 procedure to establish emergency bearer 
               
               
                   
                 services. (See Note 1) 
               
               
                   
                 If an ATTACH REQUEST has EPS attach type 
                 “originating 
               
               
                   
                 not set to “EPS emergency attach” and UE is 
                 signalling” 
               
               
                   
                 configured for NAS signalling low priority, 
               
               
                   
                 the RRC establishment cause shall be set to 
               
               
                   
                 Delay tolerant. (See Note 1) 
               
               
                   
                 If an ATTACH REQUEST has EPS attach type 
                 “emergency 
               
               
                   
                 set to “EPS emergency attach” or if the ATTACH 
                 calls” 
               
               
                   
                 REQUEST has EPS attach type not set to “EPS 
               
               
                   
                 emergency attach” but the UE initiates the 
               
               
                   
                 attach procedure on receiving request from 
               
               
                   
                 upper layer to establish emergency bearer 
               
               
                   
                 services, the RRC establishment cause shall 
               
               
                   
                 be set to Emergency call. (See Note 1) 
               
               
                   
               
               
                 Note 1: 
               
               
                 For these NAS procedures initiated by UEs of access class 12, 13 or 14 in their home country, the RRC establishment cause will be set to “High priority access AC 11-15”. For this purpose the home country is defined as the country of the MCC part of the IMSI, see 3GPP TS 22.011 [1A]. 
               
               
                 For these NAS procedures initiated by UE of access class 11 or 15 in their HPLMN (if the EHPLMN list is not present or is empty) or EHPLMN (if the EHPLMN list is present), the RRC establishment cause will be set to “High priority access AC 11-15”. 
               
               
                 Note 2: 
               
               
                 This is not applicable for mobile terminating 1xCS fallback. 
               
             
          
         
       
     
       SUMMARY OF THE INVENTION 
       [0023]    In a first embodiment of the invention, a method comprises configuring at least one processor to cause an apparatus to perform the functions of, upon a determination that the apparatus needs to communicate with a wireless networking base station, determining an extended access barring category of the apparatus and an access class barring call type of the communication, receiving extended access barring category information broadcast by the base station, receiving access class barring information broadcast by the base station, determining if the communication is subject to extended access barring, and, upon a determination that the apparatus is not subject to extended access barring, determining whether the apparatus is subject to access class barring based on the access class barring information broadcast by the base station. 
         [0024]    In another embodiment of the invention, an apparatus comprises at least one processor and a computer readable memory storing a program of instructions. The instructions, when executed by the processor, configure the apparatus to perform the functions of, upon a determination that the apparatus needs to communicate with a wireless networking base station, determining an extended access barring category of the apparatus and an access class barring call type of the communication, receiving extended access barring category information broadcast by the base station, receiving access class barring information broadcast by the base station, determining if the communication is subject to extended access barring, and, upon a determination that the apparatus is not subject to extended access barring, determining whether the apparatus is subject to access class barring based on the access class barring information broadcast by the base station. 
         [0025]    In a further embodiment of the invention, a computer readable memory stores a program of instructions. Execution of the instructions by a processor causes an apparatus to perform the functions of, upon a determination that the apparatus needs to communicate with a wireless networking base station, determining an extended access barring category of the apparatus and an access class barring call type of the communication, receiving extended access barring category information broadcast by the base station, receiving access class barring information broadcast by the base station, determining if the communication is subject to extended access barring, and, upon a determination that the apparatus is not subject to extended access barring, determining whether the apparatus is subject to access class barring based on the access class barring information broadcast by the base station. 
         [0026]    These and other embodiments and aspects are detailed below with particularity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  illustrates a wireless network according to an embodiment of the present invention; 
           [0028]      FIG. 2  illustrates a process according to an embodiment of the present invention; 
           [0029]      FIG. 3  illustrates a process according to an alternative embodiment of the present invention; 
           [0030]      FIG. 4  illustrates a process according to an alternative embodiment of the present invention; 
           [0031]      FIG. 5  illustrates a base station according to an embodiment of the present invention; and 
           [0032]      FIG. 6  illustrates a user equipment according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    The requirements detailed above, as well as other requirements, and various problems associated with meeting the requirements and with ACB and EAB in general, are solved by aspects of the present invention, of which exemplary embodiments are described below. 
         [0034]    The present invention recognizes that the approaches detailed above do not provide specific mechanisms for EAB. For example, the provisions of Annex D quoted above specify that and, further, that for both include a provision instructing the UE how to apply ordinary access class barring in cases in which a UE is configured for EAB, but EAB is not broadcast by the network or the UE passes EAB. The messages detailed above, as well as other messages defined in various applicable 3GPP technical specifications, do not include parameters indicating the specific signalling indicating that the UE is to use to apply EAB. The present invention also recognizes that it is important to insure that a UE receives the information needed to apply ordinary access class barring if it passes EAB or if EAB information is not broadcast. Specifically, the UE needs to know whether to apply access class barring for mobile originating-signalling (MO-signalling) or mobile originating-data (MO-data). Network operators do not wish to inadvertently privilege MTC or other delay tolerant devices because such devices do not happen to be subject to EAB at any particular time. In addition, if devices configured for EAB are unable to apply access class barring when they are not subject to EAB at a particular time, one logical response of network operators to this situation is to broadcast EAB information so that all devices configured for EAB are subject to EAB whenever access class barring is applied. 
         [0035]    Embodiments of the present invention therefore provide mechanisms to provide information to a UE so that a UE that is configured for EAB will, if it passes EAB or if there is no EAB information broadcast, also have or receive information needed to properly apply access class barring. 
         [0036]      FIG. 1  illustrates an exemplary wireless network  100  according to an embodiment of the present invention. The network  100  comprises a core network  102  and a base station, here implemented as an evolved node B, or eNodeB  104 . The eNodeB  104  serves a cell  106 , in which a plurality of UEs such as the UEs  108 A- 108 C may request service from the eNodeB  104 . In order to avoid excessive loads on the core network, the eNodeB  104  may receive commands from the core network  102  instructing imposition of overload control. The eNodeB  104  may suitably respond to such commands by broadcasting EAB information, including parameters such as acBarringFactor and/or acBarringtime. The eNodeB  104  accomplishes ACB and EAB by broadcasting appropriate messages. In one exemplary embodiment, the UE performs operations defined by the non-access stratum (NAS) of the wireless telecommunications protocol stack being used by the UE, such as the E-UTRAN or the UTRAN protocol stack, with the NAS providing information defining the call type and the establishment cause to the AS. This information is based on the information broadcast by the eNodeB, and is used by the AS to define how to properly apply both ACB and EAB. The information provided by the NAS suitably indicates the type of ACB being applied, typically designated by the ACB call type, as well as the EAB parameters. 
         [0037]    According to various exemplary embodiments of the invention, access class barring comprises one of three categories. These categories are barring for emergency, barring for MO-signalling, and barring for MO-data. In various exemplary embodiments detailed below, the eNodeB  104  therefore provides information enabling a determination as to whether the UE  108 A is subject to EAB, and also enabling the AS to apply the proper ACB call type if the UE  108 A is not subject to EAB. 
         [0038]      FIG. 2  illustrates a process for determining whether a UE is subject to EAB and ACB according to an embodiment of the invention. In the following discussion, the process is described as being implemented through operations of the eNodeB  104  and the UE  108 A, but it will be recognized that the reference to specific devices is non-limiting and exemplary only. 
         [0039]    At step  202 , the eNodeB  104  broadcasts category “b” EAB parameters and MO-signalling ACB parameters. According to the requirements of TS22.011 detailed above, EAB falls into one of three categories, “a”, “b”, and “c”. Category “a” is the most restrictive, barring all UEs configured for EAB. Category “b” bars all UEs that are not in their home network or an equivalent network and category “c” bars all UEs that are roaming in a non-preferred network as listed on their SIM or USIM. The information broadcast at step  202  by the eNodeB  104  indicates parameters for both EAB and ACB, which may be interpreted by the UE  108 A using separate parameters for EAB category and ACB call type. That is, mechanisms according to this embodiment of the present invention define a parameter indicating both whether the UE  108 A is configured for EAB and the applicable category if the UE  108  is configured for EAB. In parallel, an ACB call type may be defined indicating the call types, if any, that are subject to ACB. The ACB call type may suitably be defined, for example, as in 3GPP technical specifications 24.301 referred to above. 
         [0040]    At step  204 , the UE  108 A recognizes that it needs to access the network  100 . Embodiments of the present invention recognize that simply adding a new call type, such as “EAB category ‘a’” or the like, would properly exclude UEs in the EAB category being broadcast, but if a UE was not subject to EAB under the broadcast category, it would not have sufficient information to apply normal access class barring. 
         [0041]    At step  206 , the NAS layer of the UE  108 A identifies its EAB category and also identifies its ACB call type. The UE  108 A is operating in its home network, and so belongs to category “a”. That is, it is a device configured for EAB, but is subject to EAB only under circumstances in which all UEs not making an emergency request for service. The call type is MO-signalling. The determination of the category is performed by the NAS, because the category depends on the relationship of the UE  108 A to the network  100  to which the UE  108 A is attempting to gain access, and this operation is part of the NAS functionality. The NAS thus prepares two parameters, one for the EAB category and one for the ACB call type. In the present example, the EAB category indicator identifies the category as category “a” and the ACB call type indicator identifies the call type as MO-signalling. At step  208 , then, the NAS passes EAB category and ACB call type information, together with the radio resource control (RRC) establishment cause, to the access stratum (AS) layer, in the form of a first parameter of “EAB category ‘a’” and a second parameter of “MO-signalling” 
         [0042]    At step  210 , at the AS, the UE  108 A interprets the information broadcast by the eNodeB  104 , recognizing that the eNodeB  104  is broadcasting an EAB parameter indicating category “b” and an ACB call type parameter indicating MO-signalling. At step  212 , the AS evaluates its status with respect to the EAB information being broadcast and recognizes that it is not subject to EAB because it has received the information from the NAS that it belongs to category “a”. At step  214 , because the UE  108 A has passed EAB, that is, the AS has determined that the UE  108 A is not subject to EAB, the AS evaluates the status of the UE  108 A with respect to ACB, and determines that the UE  108 A is subject to ACB for the current call type. At step  216 , the AS then applies access class barring as described above, that is, by drawing a random number and determining whether the UE  108 A is barred or not and for how long based on the random number, the access class of the UE  108 A, and the barring rate and other applicable information broadcast by the eNodeB  104 . The process then terminates at step  218 . 
         [0043]      FIG. 3  illustrates the steps of a process  100  according to an alternative embodiment of the invention. The process  100  may suitably be carried out using a network such as the network  100  of  FIG. 1 . In the following discussion, the process is described as being implemented through operations of the eNodeB  104  and the UE  108 B, but it will again be recognized that the reference to specific devices is non-limiting and exemplary only. 
         [0044]    At step  302 , the eNodeB  104  broadcasts category “b” EAB parameters and MO-data ACB parameters in the same manner as described above with respect to step  202  of  FIG. 2 . At step  304 , the UE  108 B recognizes that it needs to access the network  100 . At step  306 , the NAS layer of the UE  108 B identifies its EAB category and also identifies its ACB call type. Again, the UE  108 B is operating in its home network, and so belongs to category “a”. In the present example, suppose the call type is MO-data. In the exemplary embodiment presented here, rather than preparing dual call type indicators, the NAS prepares what may be thought of as an expanded call type indicator, one providing both the EAB category and the ACB call type. At step  308 , then, the NAS passes EAB category and ACB call type information, together with the radio resource control (RRC) establishment cause, to the access stratum (AS) layer, suitably in the form of a call type of “MO-data+EAB category “a”. 
         [0045]    At step  310 , at the AS, the UE  108 B interprets the information broadcast by the eNodeB  104 , recognizing that the eNodeB  104  is broadcasting an EAB parameter indicating category “b” and an ACB call type parameter indicating MO-data. At step  312 , the AS evaluates its status with respect to the EAB information being broadcast and recognizes that it is not subject to EAB because it has received the information from the NAS that it belongs to category “a”. At step  314 , because the UE  108 B has passed EAB, AS evaluates the status of the UE  108 B with respect to ACB, and determines that the UE  108 B is not subject to ACB for the current call type. The process then terminates at step  316 . 
         [0046]    Numerous types of devices exist, and many devices, particularly machine type communication devices, are only configured to operate in one particular way. For example, a device may be configured to request service using only MO-data or MO-signalling, and may not have or need a capability to select one or the other at different times. 
         [0047]      FIG. 4  illustrates the steps of a process  400  according to still another alternative embodiment of the invention. The process  400  provides for a device to simply default to one ACB call type or another after passing EAB. Again, the process  400  may suitably be carried out using a network such as the network  100  of  FIG. 1 . In the following discussion, the process is described as being implemented through operations of the eNodeB  104  and the UE  108 A, but it will again be recognized that the reference to specific devices is non-limiting and exemplary only. 
         [0048]    At step  402 , the eNodeB  104  broadcasts category “b” EAB parameters and MO-data ACB parameters in the same manner as described above with respect to step  202  of  FIG. 2 . At step  404 , the UE  108 A recognizes that it needs to access the network  100 . At step  406 , the NAS layer of the UE  108 A identifies its EAB category, but does not identify its ACB call type. Again, the UE  108 A is operating in its home network, and so belongs to category “a”. At step  408 , the NAS passes EAB category information, together with the radio resource control (RRC) establishment cause, to the access stratum (AS) layer, suitably in the form of a call type of EAB category “a”. The NAS does not need to pass ACB call type information to the AS. 
         [0049]    At step  410 , at the AS, the UE  108 A interprets the information broadcast by the eNodeB  104 , recognizing that the eNodeB  104  is broadcasting an EAB parameter indicating category “b” and an ACB parameter of MO-signalling. At step  412 , the AS evaluates its status with respect to the EAB information being broadcast and recognizes that it is not subject to EAB because it has received the information from the NAS that it belongs to category “a”. At step  414 , because the UE  108 A has passed EAB, the AS evaluates the status of the UE  108 A with respect to ACB based on a default call type to be applied if the UE  108 A passes EAB. In the present example, suppose that this default call type is MO-data. Because the parameter being broadcast by the eNodeB  104  includes a parameter of MO-signalling, the UE  108 A is not subject to ACB for the current call type. The process then terminates at step  416 . 
         [0050]    Exemplary implementations of NAS operations performed by the processes  200 ,  300 , and  400 , respectively, may be represented by the following exemplary descriptions of NAS operations. Exemplary NAS operations that may employ embodiments of the present invention include but are not limited to attach procedures, tracking area updates, service requests, attach procedures, and numerous other NAS operations. The procedure illustrated here is modified from the procedures described above so as to present the extended capabilities of the various embodiments of the invention. It can be seen that each procedure provides mechanisms to be used in cases in which the UE needs emergency communication services. In such cases, the EAB and ACB analyses are suitably not carried out. Instead, standard procedures for emergency attachment may be used. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
               
               
                 NAS 
                   
                   
                   
               
               
                 proce- 
                   
                 Call type 
                 Call type 
               
               
                 dure 
                 RRC establishment cause 
                 (for ACB) 
                 (for EAB) 
               
               
                   
               
             
             
               
                 Attach 
                 If an ATTACH REQUEST has 
                 “originating 
                 EAB 
               
               
                   
                 EPS attach type not set to 
                 signalling” 
                 and/or 
               
               
                   
                 “EPS emergency attach”, the 
                   
                 category 
               
               
                   
                 RRC establishment cause shall be 
                   
                 a). 
               
               
                   
                 set to MO signalling except when 
               
               
                   
                 the UE initiates attach procedure 
               
               
                   
                 to establish emergency bearer 
               
               
                   
                 services. (See Note 1) 
               
               
                 . . . 
                 . . . 
                 . . . 
               
               
                   
               
             
          
         
       
     
         [0051]    The above procedure provides specifications for performing the ATTACH procedure as detailed above with respect to  FIG. 2 . The parameter indicating whether EAB is to be applied, and the category if EAB is applied, is here referred to as an EAB call type, but it will be recognized that the reference to the parameter as a call type is exemplary and non-limiting. The procedure provides for the NAS to designate a call type for ACB, and an additional parameter, separate from the ACB call type, for EAB, with the parameters being defined to allow the AS to properly interpret the status of the UE. 
         [0000]    
       
         
               
               
               
             
           
               
                   
               
               
                 NAS 
                   
                   
               
               
                 proce- 
               
               
                 dure 
                 RRC establishment cause 
                 Call type 
               
               
                   
               
             
             
               
                 Attach 
                 If an ATTACH REQUEST has 
                 “originating 
               
               
                   
                 EPS attach type not set to 
                 signalling” + 
               
               
                   
                 “EPS emergency attach”, the 
                 EAB category a). 
               
               
                   
                 RRC establishment cause shall be 
               
               
                   
                 set to MO signalling except when 
               
               
                   
                 the UE initiates attach procedure 
               
               
                   
                 to establish emergency bearer 
               
               
                   
                 services. (See Note 1) 
               
               
                 . . . 
                 . . . 
                 . . . 
               
               
                   
               
             
          
         
       
     
         [0052]    The above procedure provides specifications for performing the ATTACH procedure as detailed above with respect to  FIG. 3 . The procedure provides for the NAS to use a single call type, with the call type using modified semantics as compared to the ATTACH procedure described above. Again, this call type provides sufficient information to allow the AS to determine the status of the UE. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 NAS 
                   
                   
               
               
                   
                 proce- 
                 RRC establishment cause 
                 Category 
               
               
                   
                 dure 
                 (according 3GPP TS 36.331 [22]) 
                 (For EAB) 
               
               
                   
                   
               
             
             
               
                   
                 Attach 
                 If an ATTACH REQUEST has 
                 “a”, “b” or “c” 
               
               
                   
                   
                 EPS attach type not set to 
               
               
                   
                   
                 “EPS emergency attach”, the 
               
               
                   
                   
                 RRC establishment cause shall be 
               
               
                   
                   
                 set to MO signalling except when 
               
               
                   
                   
                 the UE initiates attach procedure 
               
               
                   
                   
                 to establish emergency bearer 
               
               
                   
                   
                 services. (See Note 1) 
               
               
                   
                 . . . 
                 . . . 
                 . . . 
               
               
                   
                   
               
             
          
         
       
     
         [0053]    The above procedure provides specifications for performing the ATTACH procedure as detailed above with respect to  FIG. 4 , simply providing the EAB category without identifying the ACB call type. Rather than relying on the NAS layer to identify the ACB call type, the AS simply implements a default call type so that there is no need for a call type identification for ACB. 
         [0054]      FIG. 5  illustrates additional details of the eNodeB  104 . It will be recognized that a typical network will include numerous base stations, including eNodeBs that may vary from the eNodeB  104  presented here, and may include base stations that are not eNodeBs. It will also be recognized that the present description is in simplified form, focusing on the components needed to carry out embodiments of the present invention. 
         [0055]    The eNodeB  104  suitably comprises a transmitter  502 , a receiver  504 , and one or more antennas, represented here as an antenna  506 . The eNodeB  104  may also include a radiocontroller  508  configured to control the transmitter  502  and the receiver  504 . The eNodeB  104  may also include a processor  510 , memory  512 , and storage  514 , communicating with one another and with the radiocontroller  508  over a bus  516 . The eNodeB  104  may suitably employ an access control module  518 , implemented as software residing in storage  514  and transferred to memory  512  as needed for execution by the processor  510 , as well as a core network communication module  520 . The access control module  518  may comprise an access class barring (ACB) module  522  and an extended access barring (EAB) module  524 . When the core network  102  is overloaded, it may transmit instructions to base stations such as the eNodeB  104  to implement one or more desired forms of access control. The core network communication module  520  may respond to such instructions by directing either or both of the ACB module  522  and the EAB module  524  to broadcast ACB or EAB parameters, as appropriate. In addition, the eNodeB  104  may broadcast EAB information, ACB information, or both, without instructions from the core network  102 , in cases in which the eNodeB itself is overloaded or in danger of overload. 
         [0056]      FIG. 6  illustrates additional details of the UE  108 A, presented here as an example. It will be recognized that a network such as the network  100  will typically include a large number of UEs, such as the  108 B, and  108 C, and additional UEs, and that any or all of these UEs which may include similar components to those of the UE  108 A, and may also include alternative or additional components as needed to perform their functions. 
         [0057]    The UE  108 A suitably similarly comprises a transmitter  602 , a receiver  604 , and one or more antennas, represented here as an antenna  606 . The UE  108 A may also include a radiocontroller  608  configured to control the transmitter  602  and the receiver  604 . The UE  108 A may also include a processor  610 , memory  612 , and storage  614 , communicating with one another and with the radiocontroller  608  over a bus  616 . The UE  108 A may suitably implement a base station communication module  618 , which may suitably comprise various segments that implement the wireless telecommunications protocol stack, most notably for present purposes an access stratum segment  620  and a non-access stratum segment  622 . The base station communication module  618  may also comprise a call type selector  624 , a network identifier  626 , and an access broadcast interpreter  628 . The network identifier  626  recognizes the network in which the UE  108 A is operating in order to allow for determination if the UE  108 A is operating in its home network, is roaming in a preferred network, or is roaming in a non-preferred network. The base station communication module  618  performs activities needed to manage various processes similar to the processes  200 ,  300 , and  400 , of  FIGS. 2 ,  3 , and  4 , respectively. For example, when the UE  108 A needs to request service, the call type selector  624  and the network identifier  626  may provide to the non-access stratum segment  622  information related to the home network, preferred network, and roaming status of the UE. This information allows the non-access stratum to identify the category of the UE  108 A and the call type. The non-access stratum segment  622  provides category and call type information to the access stratum segment  620 , allowing the access stratum segment  620  to respond appropriately to information provided by the access broadcast interpreter  628 , which examines access information broadcast by the eNodeB  104 . The access stratum segment  620  interprets this information in light of the category and call type information provided by the non-access stratum segment  622  and controls the UE  108 A appropriately. 
         [0058]    Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description. While various exemplary embodiments have been described above it should be appreciated that the practice of the invention is not limited to the exemplary embodiments shown and discussed here. 
         [0059]    Further, some of the various features of the above non-limiting embodiments may be used to advantage without the corresponding use of other described features. The foregoing description should therefore be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.