Patent Publication Number: US-2023147931-A1

Title: Managing Connection Retries Due To Access Class Barring

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This patent is a continuation of U.S. application Ser. No. 15/078,815, filed Mar. 23, 2016, which is a continuation of U.S. application Ser. No. 14/106,472, filed Dec. 13, 2013, the entire contents of which are hereby expressly incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     This invention relates to managing connection retries due to access class barring. 
     BACKGROUND 
     To manage network load, long term evolution (LTE) networks may access bar cells for UEs of specific access classes (ACs) or types of mobile originated (MO) traffic at the radio resource control (RRC) layer. For example, a network can prevent or restrict wireless devices from attempting to access the network by broadcasting access restriction parameters via ‘System information’, such as Master Information Block (MIB) and System Information Block type k (k=1, 2, . . . ). Specifically, the LTE network can restrict access for certain classes of UEs using control information for Access Class Barring (ACB), Service Specific Access Class Barring (SSAC) and Extended Access Barring (EAB). For ACB, a SIB2 may include ACB parameters for at least one of Emergency, MO data, Circuit-switched Fallback (CSFB), and MO signaling. The parameters for CSFB, MO-Data and MO-Signaling include a probability factor and a barring time for AC 0-9 and barring bits for access classes 11-15. For AC 0-9, if the UE initiates an MO call and the relevant parameters are included for the type of call, the UE generates a random number if the relevant access class barring timer is not already running. If the drawn number is lower than the value indicated by the probability, the UE may attempt to access the network. Otherwise, the UE is barred from attempting to access the network for a duration which is randomly selected based on the broadcasted barring time value. 
     If access barring is configured by the network, the SIB2 includes relevant parameters such as type of connection request for which barring is in effect and associating barring time. Examples of types of connections which may be barred along with barring time are ac-BarringForEmergency, ac-BarringForMO-Data (T303), ac-BarringForCSFB (T306/T303), and ac-BarringForMO-Signalling (T305). In summary, the access classing configuration specifies a probability of barring (ac-BarringFactor) the call origination on the user equipment (UE) and a formula to generate the timeout value before calls can be attempted, i.e., a new random number is generated and compared to the probability. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic block diagram of an example mobile communication. 
         FIG.  2    is an example mobile device for managing connection retries. 
         FIG.  3    is a call flow for managing connection retries for a voice application. 
         FIG.  4    is a call flow for managing connection retries for an SMS application. 
         FIG.  5    is a call flow for managing connection retries for a data application. 
         FIG.  6    is a flow chart illustrating an example method for refraining retries until expiration of an access-class-barring timer. 
         FIG.  7    is a flow diagram for managing for managing a connection retry due to access class barring. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     The present disclosure is directed to managing a retry of a connection request for a user application due to LTE access class barring. For example, the non-access stratum (NAS) module or the user application may prevent a retry of a connection request until after expiration of an access-class-barring timer. In these instances, the NAS module or the user application may substantially align a retry timer for a user application with the access-barring-class timer for a radio resource control (RRC) module. In doing so, the NAS module or the user application may improve the access time to the network by aligning the retry with at the expiry of the access barring timer and also reduce power consumption by preventing a retry unnecessary futile retry attempts between NAS or application layer and RRC layer before expiration of the access-class-barring timer. In some implementations, a user application sends a connection request to the NAS module. A user application can include a data application, a short message service (SMS) application, a voice application, or other applications. In response, the NAS module can transmit a connection establishment request to the RRC module if the appropriate access class barring is not already active. In some instances, the NAS module may determine the type of MO traffic for the user application and indicate the traffic type to the RRC module. For example, the NAS module may indicate that the MO traffic request is for a circuit-switched voice call or a Voice over LTE (VoLTE) call. The RRC module executes an access-class-barring check or determines whether an access-class-barring timer is currently active. If the check fails or the timer is active, the RRC module notifies the NAS module of a failure of or a rejection to the connection establishment request due to access class barring. To substantially prevent a subsequent retry to be performed too soon or too late, the NAS module or the user application refrains sending a subsequent retry until at least expiration of the access-class-barring timer. In some instances, the NAS module or the user application substantially aligns the retry timer for the user application to the access-class-barring timer that resulted in the access class barring. 
     In some implementations, the timers can be substantially aligned using one or more of the following: directly informing the user application when the access-class-barring timer will expire by either the NAS module or the RCC module; having the user application request the timeout value directly from the RRC module or the RCC via the NAS module; in response to expiration of the timer, automatically triggering a retry of the connection request; or others. For barring due to MO data, the retry timer can be substantially aligned with T303. For barring due to CSFB, the retry timer can be substantially aligned with T306 and T303. For barring due to MO signaling, the retry timer can be substantially aligned with T305. In doing so, the user application matches the countdown of the retry timer to the countdown of the access-class-barring timer. 
       FIG.  1    is a schematic block diagram of an example mobile communication system  100 . The mobile communication system  100  shown in  FIG.  1    may include one or more network nodes (e.g.,  112   a  and  112   b ). The network nodes may take several forms in a mobile communication system, such as (but not limited to) an evolved Node B (eNB), a base station, a Node B, a wireless access point, a radio network controller, a base transceiver station, a layer two relay node, a layer three relay node, a femto cell, home eNB (HeNB), a home Node B (HNB), a base station controller, or other network node that includes radio resource control. In the LTE example of  FIG.  1   , the network nodes are eNBs  112   a  and  112   b . The example mobile communication system  100  of  FIG.  1    may include one or more radio access networks  110 , core networks (CNs)  120 , and external networks  130 . In some implementations, the radio access networks  110  may be an evolved-UMTS terrestrial radio access networks (E-UTRAN). In addition, in certain instances, the core networks  120  may be evolved packet cores (EPCs). Further, there may be one or more mobile electronic devices  102   a ,  102   b  operating within the mobile communication system  100 . In some implementations, 2G/3G systems  140  may be a Global System for Mobile communication (GSM), Interim Standard 95 (IS-95), Universal Mobile Telecommunications System (UMTS), or a CDMA2000 (Code Division Multiple Access) and also integrated into the mobile communication system  100 . 
     As illustrated, the radio access network  110  includes eNB  112   a  and eNB  112   b . Cell  114   a  is the service area of eNB  112   a , and Cell  114   b  is the service area of eNB  112   b . In this example, UEs  102   a  and  102   b  operate in Cell  114   a  and are served by eNB  112   a . The UEs  102   a  and  102   b  may be any electronic device used by an end-user to communicate, for example, within the mobile communication system  100 . The UEs  102   a  and  102   b  may transmit voice data, video data, user data, application data, multimedia data, text, web content and/or any other content. 
     As previously mentioned, the UE  102   a ,  102   b  can include any hardware, software, firmware, or combination thereof to prevent a retry of a connection request until at least expiration an access-class-barring timer. For example, the UE  102   a ,  102   b  may substantially align a retry timer to an access-class-barring timer. In these instances, the timeout value for the access-class-barring timer to the application requesting the connection. The UE  102   a ,  102   b  may receive control information for Access Class Barring (ACB), Access Control for circuit-switched fallback (CSFB), or Extended Access Barring (EAB) via a SIB2. Based on the control information, the UE  102   a ,  102   b  can set an access-class-barring timer that prevents certain groups of UEs from attempting to access eNB  112   a . A user application executing on the UE  102   a ,  102   b  may generate a connection request and receive a failure or rejection due to access class barring. In response to the access class barring, the UE  102   a ,  102   b  can prevent a retry of the RRC connection request until after expiration of the access-class-barring timer. For example, the UE  102   a ,  102   b  may substantially align the retry timer for the user application with the access-class-barring timer. Once the access-class-barring timer expires, the UE  102   a ,  102   b  can retry the connection request. Aligning the retry of the connection request and refraining attempts until expiration of the access-class-barring timer improves access time to the network and will save battery consumption and enhance user experience. 
     In general, the UE  102   a  or  102   b  may be referred to as mobile electronic device, user device, mobile station, subscriber station, portable electronic device, mobile communications device, wireless modem, or wireless terminal. Examples of a UE (e.g. UE  102   a  or  102   b ) may include a cellular phone, personal data assistant (PDA), smart phone, laptop, tablet personal computer (PC), pager, portable computer, portable gaming device, wearable electronic device, or other mobile communications device having components for communicating voice or data via a mobile communication network. 
     Other examples of a UE include, but are not limited to, a television, a remote controller, a set-top box, a computer monitor, a computer (including a tablet, a desktop computer, a handheld or laptop computer, a netbook computer), a microwave, a refrigerator, a stereo system, a cassette recorder or player, a DVD player or recorder, a CD player or recorder, a VCR, an MP3 player, a radio, a camcorder, a camera, a digital camera, a portable memory chip, a washer, a dryer, a washer/dryer, a copier, a facsimile machine, a scanner, a multi-functional peripheral device, a wristwatch, a clock, and a game device, etc. The UE  102   a  or  102   b  may include a device and a removable memory module, such as a Universal Integrated Circuit Card (UICC) that includes a Subscriber Identity Module (SIM) application, a Universal Subscriber Identity Module (USIM) application, or a Removable User Identity Module (R-UIM) application. Alternatively, the UE  102   a  or  102   b  may include the device without such a module. The term “UE” can also refer to any hardware or software component that can terminate a communication session for a user. In addition, the terms “user equipment,” “UE,” “user equipment device,” “user agent,” “UA,” “user device,” and “mobile device” can be used synonymously herein. 
     A radio access network is part of a mobile communication system which implements a radio access technology, such as UMTS, CDMA2000 and 3GPP LTE. For example, the radio access network (RAN)  110  included in an LTE telecommunication system is called an EUTRAN. The EUTRAN can be located between the UEs and core network  120  (e.g. an evolved core network, EPC). The EUTRAN includes at least one eNB. The eNB can be a radio base station that may control all or at least some radio related functions in a fixed part of the system. The at least one eNB can provide radio interface within their coverage area or a cell for the UEs to communicate. The eNBs may be distributed throughout the cellular network to provide a wide area of coverage. The eNBs directly communicate with one or more UEs, other eNBs, and the core network. 
     Once the eNB  112   a  determines that network congestion or capacity has exceeded a threshold, the eNB  112   a    102   b  may broadcast a SIB2 including control information for at least one of Access Class Barring (ACB), Access Control for circuit-switched fallback (CSFB), or Extended Access Barring (EAB). The control information prevents certain groups of UEs, i.e., access classes (ACs), from attempting to access the eNB  112   a  for a certain period of time. For example, the control information can include at least one of ac-BarringForMO-Data (T303), ac-BarringForCSFB (T306/T303), and ac-BarringForMO-Signalling (T305). For any of the classes, the control information specifies a probability of barring the connection and a formula to generate the timeout value before a connection can be attempted. 
     In general, the eNBs  112   a  and  112   b  may be the end point of the radio protocols towards the UEs  102   a ,  102   b  and may relay signals between the radio connection and the connectivity towards the core network  120 . In certain implementations, the EPC may be the main component of a core network  120 . The core network  120  may include a backbone network, which may be a central part of the mobile communication system  100 . The core network  120  may include other components, such as (but not limited to) a mobility management entity (MME), a serving gateway (SGW), and/or a packet data network gateway (PGW). The MME may be the main control element in the core network  120  responsible for the functionalities comprising the control plane functions related to subscriber and session management. The SGW can serve as a local mobility anchor, such that the packets are routed through this point for intra radio access network  110  (e.g. intra-EUTRAN) mobility and mobility with other legacy 2G/3G systems  140 . The SGW functions may include the user plane tunnel management and switching. The PGW may provide connectivity to the services domain comprising external networks  130 , such as the IP networks. The UEs  102   a ,  102   b , radio access network  110  (e.g. EUTRAN), and core network  120  (e.g EPC) are sometimes referred to together as the evolved packet system (EPS). 
       FIG.  2    is a block diagram of an example mobile device  102  configured to prevent a retry of a connection request that was access class barred. For example the mobile device  102  may substantially align a retry timer for a connection request to an access-class-barring timer. The device  102  includes a plurality of device applications  202 ,  204 ,  206 , a NAS module  208 , and an RRC module  210 . The device applications include a voice application  202  (e.g., telephony application), an SMS application  204 , and a data application  206  (e.g., an electronic mail application, a web browser application) that communicate with, for example, the eNB  112   a  illustrated in  FIG.  1   . The device applications  202 ,  204 ,  206  may be software applications stored in a memory sub-system and executed by a processing sub-system. For example, the device applications may be stored in the flash memory, RAM, or a combination thereof and executed by the microprocessor, digital signal processor (DSP), or a combination thereof of the device  102 . 
     The user application  202 ,  204 ,  206  can include any hardware, software, firmware, or combination thereof for preventing a retry of a connection request that was access class barred. As mentioned above, the applications  202 ,  204 ,  206  or the NAS module  208  may substantially align a retry timer for one of the applications  202 ,  204 ,  206  with an access-class-barring timer for the RRC module  210 . For example, the NAS module  208  may receive a service request from the application  202 ,  204 , or  206  and, in response to the request, send an RRC connection establishment request to the RRC module  210 . In some implementations, the NAS module  208  may determine a type of MO traffic for the application  202 ,  204 , or  206  and indicate the traffic type to the RRC module  210 . In response to a failure or a rejection from the RRC module  210 , the user application  202 ,  204 ,  206  may prevent a retry of the connection request until expiration of the access-class-barring timer. When the retry timer and the access-class-barring timer are aligned, the retry timer and the access-class-barring timer can timeout at substantially the same time. In some implementations, a retry can be prevented using one or more of the following: informing the user application  202 ,  204 , or  206  of a timeout value for the access-class-barring timer; having the user application  202 ,  204 , or  206  to request the timeout value directly from the RRC module  210  or the RRC module  210  via the NAS module  208 ; in response to expiration of the timer, having the RRC module  210  automatically triggering a retry of the connection request; or others. For barring due to MO data, the NAS module  208  or the user application  202 ,  204 ,  206  can substantially align the retry timer with T303. For barring due to CSFB, the NAS module  208  or the user application  202 ,  204 ,  206  can substantially align the retry timer with T306 and T303. For barring due to MO signaling, the NAS module  208  or the user application  202 ,  204 ,  206  can substantially align the retry timer with T305. 
     In general, the NAS module  208  includes any hardware, software, firmware, or combination thereof for communicating with, for example, the eNB  112   a . In other words, the NAS module  208  applies the wireless protocols to interface the application layers  202 ,  204 ,  206  with the eNB  112   a . The NAS module  208  can be a functional layer in the protocol stack for communication between an access network and the mobile device  102 , which supports signaling and traffic between the access network and the mobile device  102 . The NAS protocols may not be specific to a particular radio access technology (RAT). In an evolved packet system (EPS), the NAS protocols can include mainly protocols for mobility management and session management between mobile device  102  and the mobility management entity (MME). In an example, the AS layer and/or NAS layer processing and/or signaling can be provided by a modem module (or device). 
     The RRC module  210  can include any hardware, software, firmware, or combination thereof for executing checks for access class barring. For example, the RRC module  210  may receive an RRC connection request from the NAS module  208  and perform the access baring check according to the traffic type or access class to determine whether the cell is barred. If the cell is barred the RRC module  210  starts the appropriate access-class-barring timers if not currently active and sends a notification of a failure or rejection to the NAS module  208 . In some instances, the RRC module  210  may send the timeout value to the NAS module  208  with the rejection or in response to a request. In some implementations, the user applications  202 ,  204 ,  206  may query the RRC module  210  directly to determine the retry time to align with the access-class-barring timer expiry. 
     In general, the RRC module  210  includes the access stratum manager software and any associated hardware for interfacing the eNB  112   a  with the NAS module  208 . The RRC module  210  is operable to establish a communication link between the NAS module  208  and the eNB  112   a . In addition, the RRC module  210  is further operable to maintain the communication link between the NAS module  208  and the eNB  112   a . For example, RRC module  210  can include protocols specific to a particular radio access technology (RAT), such as long term evolution (LTE) and third generation (3G) and second generation (2G) digital wireless technology. 2G wireless technology can include cellular telecom protocols using the global system for mobile communications (GSM) standard. GSM (originally groupe spécial mobile) is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by wireless devices (e.g., mobile phones). 3G wireless technology can include protocols that comply with the international mobile telecommunications-2000 (IMT-2000) specifications by the international telecommunication union, such as universal mobile telecommunications system (UMTS), code division multiple access 2000 (CDMA2000), and Worldwide interoperability for Microwave Access (WiMAX). UTMS is a 3GPP radio access technology for networks using wideband-code division multiple access (W-CDMA). CDMA2000 uses code division multiple access (CDMA) channel access to send voice, data, and signaling data between wireless devices (e.g., mobile phones) and cell sites. 3G wireless technology can provide applications in wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile television (TV). 
       FIG.  3    illustrates a call flow  300  for managing a retry for voice-call connection request. In particular, the voice application  202  sends a connection request  302  to the NAS module  208 . The connection request  302  may comprise a request to initiate a Circuit-switched voice call (CSFB voice call). In response to the request, the NAS module  208  sends an RRC connection establishment request  304  to the RRC module  210 . In some implementations, the NAS module  208  determines a type of traffic for the voice application  202  and indicates the traffic type to the RRC module  210 . If the access class barring check fails, the RRC module  220  sends an indication  306  of a failure or rejection due to access class barring. In some implementations, the RRC module  210  may indicate a timeout value to the NAS module  208 . The NAS module  208  sends a notification  308  of the failure or rejection to the voice application  202  and the voice application restrains the retry until after expiration of the access-class-barring timer of the RCC module  210 . For example, the NAS module  208  may send the timeout value to the voice application  202  such that the voice application  202  sets a retry timer to expire at the timeout value. In some implementations, the voice application requests or extracts the timeout value from NAS module  208  or the RRC module  210 . 
       FIG.  4    illustrates a call flow  400  for managing a retry for SMS connection request. In particular, the SMS application  204  sends a connection request  402  to the NAS module  208 . The connection request  402  may comprise a request to send an SMS message. In response to the request, the NAS module  208  sends an RRC connection establishment request  404  to the RRC module  210 . In some implementations, the NAS module  208  determines a type of traffic for the SMS application  204  and indicates the traffic type to the RRC module  210 . In response to performing the access barring check, the RRC module  220  sends an indication of a failure or rejection due to access class barring. In some implementations, the RRC module  210  may indicate a timeout value to the NAS module  208 . The NAS module  208  sends a notification of the failure or rejection to the SMS application  204  and the SMS application  204  restrains a retry until after expiration of the access-class-barring timer for the RCC module  210 . For example, the NAS module  208  may send the timeout value to the SMS application  204  such that the SMS application  204  sets a retry timer to expire at the timeout value. 
       FIG.  5    illustrates a call flow  500  for managing a retry for data connection request. In particular, the data application  206  sends a connection request  502  to the NAS module  208 . The connection request  502  may comprise a request to initiate a data connection. In response to the request, the NAS module  208  sends an RRC connection establishment request  504  to the RRC module  210 . In some implementations, the NAS module  208  determines a type of traffic for the data application  206  (e.g., user data, signaling) and indicates the traffic type to the RRC module  210 . In response to performing the access class barring check, the RRC module  220  sends an indication of a failure or rejection due to access class barring  506 . In some implementations, the RRC module  210  may indicate a timeout value to the NAS module  208 . The NAS module  208  sends a notification of the failure or rejection to the data application  206  and the data application  206  restrains a retry of the connection request until after expiration of the access-class-barring timer of the RRC module  210 . For example, the NAS module  208  may send the timeout value to the data application  206  such that the data application  206  sets a retry timer to expire at the timeout value. 
       FIG.  6    is a flowchart illustrating a method  600  for preventing a retry of a connection request for a user application until expiration of a timer for access class barring. Method  600  begins at step  602  where a connection request is received. For example, the NAS module  208  in  FIG.  2    may receive a connection request form voice application  202  requesting establishment of a connection for a voice call. At step  604 , a category for the requesting application is determined by the application or entity requesting the connection. For example, the NAS module  208  may determine the category of the voice application  202  such as CSFB. Next, at step  606 , an RRC connection establishment request that identifies the category is sent. Returning to the example, the NAS module  208  may send an RRC connection establishment request to the RRC module  210  that identifies the type of connection requested. At step  608 , a failure or a rejection for access class barring is received. As for the example, the NAS module  208  receives, from the RRC module  210 , a notification of a failure or rejection for access class barring. In some implementations, the notification includes a timeout value for the access-class-barring timer. In some implementations, the application is notified, at step  610 , that the connection request has failed or been rejected. Next, at step  612 , a retry of the connection request is refrained until expiration of the access-class-barring timer. In the example, the NAS module  208  may send the timeout value to the voice application  202  in which case the voice application  202  can set expiration of the retry timer to the timeout value. 
       FIG.  7    illustrates a flow diagram  700  for managing a retry for a connection request. At step  1 , the application  702  sends a connection request to the NAS  704 . For example, the request may be to send data or an SMS, start a voice call, execute CSFB, or other. At step  2 , the NAS  704  sends, to the RRC  706 , a request to create an RRC connection if one does not already exist. The RRC  706  executes an access-class-barring check, if necessary, and establishes an RRC connection if the access-class-barring check succeeds, which is indicated with the dashed line at step  3 . If the access-class-barring check fails (or for another reason), the RRC  706  sends an RRC connection establishment failure, including the cause, to the NAS  704 , which is indicated with a solid line in step  3 . If the connection was successful, the NAS  704  sends a successful notification to the application  702 , which is indicated by a dashed line at step  4 . If unsuccessful, the NAS  704  sends a connection request failure, including the case, to the application  702 , which is indicated by a solid line at step  4 . In some implementations, the NAS  704  can send the timeout value for the access-class-barring timer to the application  702 . In other implementations, the application  702  may directly request the timeout value directly from the NAS  704 , and in response, the NAS  704  requests the timeout value from the RRC, which is illustrated at step  5   a . In some instances, the application  702  may directly request the timeout value from the RRC  706 . At step  6 , the RRC  706  may directly send an indication of access-class-barring timer timeout to the application  702 , which can trigger a retry. 
     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.