Method and system for reducing frequent connection establishment requirements between network elements

Disclosed are a method, apparatus, and system for managing connections in a wireless communication network. When a user equipment device (UE) transitions between an idle state and an active state, a radio link is established between a base station and the UE and a core network link is established between the base station and a core network entity. In response to detecting that no data packets are exchanged between the UE and the base station, a timer is initiated. Further, in response to detecting that data packets are being exchanged between the UE and the base station, the timer is reset. The radio link is released in response to the timer reaching a first predetermined value associated with a first inactivity period and the core network link is released in response to the timer reaching a second predetermined value associated with a second inactivity period.

BACKGROUND

A typical cellular wireless communication system or network includes a number of antenna systems that radiate radio frequency (RF) radiation patterns to define wireless coverage areas, such as cells and cell sectors. The antenna systems or base stations are in turn coupled to one or another form of controller, which can be coupled to a telecommunications switch or gateway. The switch or gateway may then be coupled with a transport network, such as the public switched telephone network (PSTN) or a packet-switched network (e.g., the Internet).

A user equipment device (UE), such as a cell phone, tablet computer, tracking device, embedded wireless module, and other wirelessly equipped communication devices, can operate in the cells defined by the radiation patterns from the base stations. With the typical wireless communication system described above, a communication channel or link can be established between the UE and the transport network, via the base station, controller, switch or gateway, and possibly other elements. Thus, a UE operating within a coverage area of a base station can engage in air interface communication with the base station and can thereby communicate via the base station with various remote network entities or with other UEs.

In general, the wireless communication system may operate in accordance with a particular air interface protocol or radio access technology. Examples of existing air interface protocols include CDMA (e.g., 1xRTT and 1xEV-DO), LTE (e.g., FDD LTE and TDD LTE), WiMAX, iDEN, TDMA, AMPS, GSM, GPRS, UMTS, EDGE, MMDS, WI-FI, and BLUETOOTH. Each protocol may define its own procedures for initiation of communications, establishment of communication links, release of communication links, handoff between coverage areas, and other functions related to air interface communication.

Further, depending on the specific underlying technologies, protocols, and architecture of a given wireless communication system, the various elements of the system may take different forms and may make up different portions of the wireless communication system. In one example, the base stations, the communication devices, and possibly other elements generally make up a radio access network (RAN) portion of the system. Further, in the present example, the controllers, switches, gateways, and perhaps other elements generally make up a core network portion of the system. Although, in practice, different elements may overlap in one or more portions of the wireless communication system.

Illustratively, in an LTE system, the base station is usually referred to as an eNodeB and a mobility management entity (MME) can be coupled to the eNodeB to coordinate functionality between multiple eNodeBs. Each MME and eNodeB can also be coupled to a serving gateway (SGW) and/or a packet gateway (PGW). In a CDMA system, the base station is referred to as a base transceiver system (BTS) and the BTS is usually under the control of a base station controller (BSC). Further, each BSC can be coupled to a mobile switching center (MSC) and/or a packet data serving node (PDSN) for instance. Other architectures and operational configurations of the wireless communication system are possible as well.

OVERVIEW

Generally, a UE can transition between an idle state and an active communication state. When in the idle state, such as when the UE is first turned on, no active data transfer or communication is being performed between the UE and the wireless communication system. However, in the idle state, the UE can communicate with the wireless communication system, such as with one or more of the base stations, to select a suitable cell with good signal quality or to request transition to the active state, for instance.

When the UE transitions from the idle state to the active state, such as when a request is made through the UE to access a webpage, the UE communicates with the wireless communication system to establish an active communication link or connection over which data can be transferred. This active communication link may actually include one or more communication links between the UE and elements of the wireless communication system. Illustratively, the active communication link may include a link between the UE and a base station (e.g., a radio link) and a link between the base station and a core network element or entity (e.g., a core network link). In general, the establishment of these links includes messaging and processing between the UE, the base station, and the core network entity to identify and assign necessary network resources for the links. Once the network resources are identified and assigned, the links can be established and data can be transferred between the UE and the wireless communication system.

In order to make efficient use of network resources, the established communication links and assigned network resources can be released after a period of inactivity, which can be characterized by a period of no active data transfer (or no requests to restart active data transfer) between the UE and the other network elements. Typically, the duration of the inactivity period is set fairly low to preserve battery life of the UEs. In one non-limiting example, the duration of the period of inactivity before the communication links and networks resources are released is between about 5-10 seconds. However, since this inactivity period is short, the communication links and assigned network resources may be released and then need to be reestablished repeatedly during a short period of time.

For example, a user may access a webpage through the UE and begin reviewing the contents of the webpage, during which review the inactivity period may lapse and the communication links and network resources released along with the UE transitioning to the idle state. Shortly thereafter, the user may finish reviewing the webpage and click on a link in the webpage, which will trigger a transition back to the active communication state and the reestablishment of the communication links and reassignment of the network resources. This release and reestablishment of communication links can occur repeatedly over a relatively short period and increases processing requirements on the wireless communication system. Further, the release and reestablishment of communication links reduces efficiency of UE applications due to increased connection setup time.

The present disclosure addresses these issues by introducing a second inactivity period for certain communication links, in particular, the core network link between the base station and the core network entity. The core network link and the associated network elements are not affected by the same battery life preservation concerns that affect the UE. Consequently, the duration of the second inactivity period can be longer than the first inactivity period so that the core network link will remain established for a longer period. Thus, each time the UE transitions back to the active state, the core network link will already be established to facilitate immediate flow of data (after the radio link between the UE and the base station is re-established).

In another example, the duration of the second inactivity period can be adjusted, for example, in response to a frequency of release and reestablishment of the communication link, although, in general, the second inactivity period may still be longer than the first inactivity period. Thus, for example, the second inactivity period can be introduced and/or extended in duration based on a determination that a communication link between the UE and the wireless communication system has been released and re-established with a frequency greater than a given threshold, such as greater than three times within twenty seconds.

These as well as other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings. Further, it should be understood that the disclosure provided by this overview and the other description throughout this document is intended to illustrate the invention by way of example only and that numerous variations may be possible.

DETAILED DESCRIPTION

The present disclosure will be described by way of example in a scenario where a UE transitions between idle and active states. Referring to the drawings,FIG. 1is an example block diagram of a wireless communication network10that may be used in an LTE system. It is to be understood, however, that other network architectures could be used in other examples.

InFIG. 1, the wireless communication network10is illustrated with a base station12and a core network14. The base station12and the core network14function to provide a UE16with cellular wireless communication service, such as connectivity with a transport network18. The transport network18can be the PSTN or a packet-switched network, for instance. In LTE terminology, the base station16corresponds to an eNodeB and generally includes transceiver equipment and antennas (e.g., on an antenna tower) arranged to define one or more cellular wireless coverage areas such as a cell and cell sectors. Further, in the context of LTE, the core network14includes an evolved packet core (EPC) network, which, in turn, includes various core network or EPC nodes or entities. In the present example, the core network entities include an MME20, an SGW22, a PGW24, a home subscriber server (HSS)26, and a policy and charging rules function (PCRF)28.

The UE16, which can be a wireless telephone, wireless e-mail device, wirelessly-equipped computer (such as handheld, tablet, or laptop computers), or other type of wireless communication device, can be engaged in communication sessions with one or more endpoints30via the base station12. The endpoint(s)30may include, for example, one or more voice-over-packet (VoP) communication devices, e-mail servers, messaging servers, streaming media servers, gaming servers, and/or Web servers. In one example, the endpoint(s)30are communicatively coupled to the transport network18, which can be a packet-switched network. Thus, generally a communication session between the UE16and the endpoint(s)30may involve the exchange of packets containing voice, video, text, or other data.

Further, althoughFIG. 1shows the base station12serving one UE16, it is to be understood, that a base station may serve a greater or fewer number of user devices at a particular point in time. Generally, in practice, the wireless communication network10may include a plurality of UEs16, base stations12, core networks14(and core network entities), and/or transport networks18, it being understood thatFIG. 1only represents one non-limiting arrangement of the network.

To support communications between the UE16and the transport network18, the wireless communication network10may include the PGW24, which can allocate Internet Protocol (IP) addresses for the UE. Further, the PGW24may exchange packets with the base station12via the SGW22. The SGW22may also serve as an anchor point for communication sessions when UEs move between base stations.

The wireless communication network10may also include one or more control nodes that control communications involving UEs. For example, the network10includes the MME20, which controls communications between the UE16and SGW22. The MME20may, in turn, be communicatively coupled to the HSS26, which stores subscriber information.

The UE16may operate in one of three possible states: detached, idle, and active. The UE16typically operates in the detached state while it is searching for and registering with the network10. The UE16typically operates in the active state once it has registered with the network10and has a radio resource control (RRC) connection or radio link40with an eNodeB (e.g., while actively engaged in a communication). Further, the UE16typically operates in the idle state when it is registered but is not actively engaged in a communication, and thus does not have an RRC connection40.

Referring more particularly to the transition of the UE16between the idle and active states, during this transition, a network attachment process is performed to register the UE, identify and assign network resources, and establish a dedicated communication connection or link between the UE and the network10. This network attachment process can be performed when the UE16is requesting IP-based internet services, for instance. Generally, the network attachment process and other processes for registering a UE and establishing dedicated communication links are known. An illustrative example of a network attachment process will now be discussed in the context of LTE and with further reference toFIG. 1.

In the present example, the network attachment process begins with the UE16sending an RRC connection request to the eNodeB12. The RRC connection request generally includes identification information for the UE and RRC connection parameters. Responsive to the RRC connection request, the eNodeB12configures and establishes the RRC connection40with the UE16.

The UE16can then send an attach request message to the MME20via the eNodeB12to request establishment of one or more core network connections or links between the base station12and the core network14. The attach request message can be sent through the RRC connection40between the UE16and the eNodeB12and an S1-MME connection42between the eNodeB and the MME20. Further, the attach request message (and other messages discussed in this example) can be sent over a non-access stratum (NAS) layer of the network10.

In response to the attach request message, the MME20identifies and authenticates the UE12based on authentication information in the attach request message or received from the HSS26. During this identification/authentication process, the MME20can also update the HSS26with a location of the UE16. In the present example, the MME20and the HSS26can communicate over an S6a connection44.

The MME20then selects an SGW22and a PGW24to be used to establish the communication link with the UE16. The MME20can select the SGW22and the PGW24based on information in the attach request message and location information in the HSS26related to the UE16, for example. The MME20then sends a create session request to the selected SGW22, such as over an S11 connection46between the MME and the SGW.

The create session request is received by the SGW22, which creates an access bearer for the UE16. More particularly, the SGW22creates an access bearer for a S1-U connection48between the SGW and the eNodeB12. The SGW22also communicates with the selected PGW24, such as over an S5 or S8 connection50between the SGW and the PGW, to create access bearers for the connection50and for an SGi connection52between the PGW and the transport network18. These access bearers and connections are later used to serve the UE16in the active state. The PGW24creates these access bearers and allocates an IP address for the UE16. The PGW24can also communicate with the PCRF28, such as over a Gx interface54, to identify billing, rating, or charging information for the UE16. Generally, these access bearers are sets of network parameters that define how data over a connection (e.g., data to and from the UE16) is treated, such as with a guaranteed bit rate or not. The creation of these access bearers also involves identifying and assigning necessary network resources for the active communication links between the UE16and the network10. After the access bearers are created, the SGW22sends a create message response back to the MME20.

The MME20now sends a context setup request to the eNodeB12, which includes an attach accept message for the UE16. After receiving the context setup request, the eNodeB12establishes security parameters with the UE16and reconfigures resources to the UE by sending an RRC connection reconfiguration request to the UE. The UE16updates its RRC connection configuration in response to the request and responds to the eNodeB12with a reconfiguration complete message and with other parameters that are later used by the SGW22to establish the various access bearers.

The eNodeB12passes the reconfiguration complete message and the other parameters to the MME20, which, in turn, passes the other parameters to the SGW22. Responsively, the SGW22completes the allocation and establishment of the access bearers for the connection48with the eNodeB12. The SGW22also communicates with the PGW to complete the allocation and establishment of the access bearers for the connections50,52. Thereafter, the SGW22responds to the MME20with a modify bearer response and the MME responds to the UE16with an activation message. The MME20also creates and stores a context for the UE, which includes user subscription information downloaded from the HSS44and also holds dynamic information, such as a list of bearers that were created and capabilities of assigned network resources.

Now, the UE16is transitioned to the active communication state and is connected to the network10through the reconfigured RRC connection (radio link)40and a core network link, which in the present example includes one or more connections or links to the core network, such as one or more of the connections42-54.

As discussed above, the radio link, the core network link, and associated network resources that are established or assigned when the UE16is transitioned to the active state can be released after a period of inactivity. Typically, the release of the links and resources involves the eNodeB12sending a detach request to the MME20. In response to the detach request, the MME20sends a delete session request to the SGW22, which in turn sends the delete session request to the PGW24. The PGW24can communicate with the PCRF28to terminate the session by deleting the access bearer for the connection50and releasing associated network resources. The PGW24sends a delete session response or confirmation to the SGW22. Subsequently or concurrently, the SGW22deletes the access bearer(s) for the connections48and/or46and sends a delete session response or confirmation to the MME20. The MME20communicates with the UE and the eNodeB to release the links40,42and any associated resources. The UE16is then transitioned to the idle state.

Thereafter, to transition the UE16back to the active state, the various communication links need to be re-established, as discussed above. This release and re-establishment of the communication links and assignment of necessary resources creates a processing burden on the wireless communication system, especially when performed repeatedly over a short period of time. The present disclosure addresses this processing burden by separately controlling the release of different links and network resources. More particularly, the flowcharts ofFIGS. 2A and 2Bdepict functions that can be carried out in accordance with the present disclosure to control the release of these links and network resources.

Referring first toFIG. 2Aand with further reference toFIG. 1, a UE is transitioned between the idle state and the active state by establishing a radio link, at block60, and establishing a core network link, at block62. An example of these functions is described above, although other examples are also possible.

After the links are established at blocks60,62, a timer can be initiated at block64. In one example, the eNodeB initiates the timer. Although, in other examples, the timer can be associated with and/or initiated by the UE, the MME, or some other component of the network. In the present example, the eNodeB initiates the timer in response to detecting that no data packets are exchanged between the UE and the base station. The timer is reset at block66if the eNodeB detects that data packets are being exchanged between the UE and the base station.

At block68, the eNodeB releases the radio link with the UE (and associated network resources) when the timer reaches a first predetermined (radio link) value that corresponds to a radio link inactivity period. This radio link inactivity period is set fairly low so that the radio link with the UE can be released after a relatively short period of inactivity to help preserve battery life of the UE. For example, this radio link inactivity period can be between 5-10 seconds.

At block70, the eNodeB releases the core network link between the eNodeB and the core network (and associated network resources) when the timer reaches a second predetermined (core network) value that corresponds to a core network link inactivity period. As described above, the core network link can include one or more of the links42-52described above in relation toFIG. 1. The core network link inactivity period can be longer than the radio link inactivity period, such that the core network link will be maintained longer than the radio link. Consequently, if the UE transitions back to the active state before the timer reaches the core network value, the core network link will still be available to facilitate immediate flow of data (after the radio link is re-established).

FIG. 2Bis similar toFIG. 2Aand includes identical blocks60-68but also introduces a block72, at which the eNodeB determines that the radio link is released and re-established with a particular frequency above a given threshold. More particularly, after the radio link is released at block68, the UE can again transition back to the active state by re-establishing the radio link in response to a request from the UE, for example. Thereafter, as described above, the eNodeB can release the re-established radio link again if the timer reaches the first predetermined value. At block72, the eNodeB determines whether this release and re-establishment of the radio link has occurred a given number of times within a set period of time, which corresponds to the frequency of release and re-establishment of the radio link. If the eNodeB determines that this frequency is greater than a given threshold, such as releasing and re-establishing the radio link three times within twenty seconds, then the eNodeB can modify the second predetermined (core network) value.

At block74ofFIG. 2B, which is similar to block70ofFIG. 2A, if the eNodeB determines that the frequency is greater than the given threshold, the eNodeB can dynamically adjust the core network inactivity period, such as by setting the core network inactivity period to be greater than the first inactivity period. In one example, the eNodeB can set the length of the core network inactivity period to be generally proportional to the frequency of release and re-establishment of the radio link. In this example, generally, the eNodeB can set the length of the core network inactivity period higher for higher frequencies of release and re-establishment of the radio link and lower for lower frequencies of release and re-establishment.

In another example, the core network inactivity period may not be triggered until the frequency of release and re-establishment of the radio link is above the given threshold. In this example, the core network link can be released along with the radio link unless the eNodeB determines that the radio link and the core network link are being released and re-established with a particular frequency above the given threshold.

As discussed above, the core network inactivity period can be used to maintain the core network link for a longer period than the radio link. Thus, if the UE transitions back to the active state before the timer reaches the core network value, the core network link will still be available to facilitate immediate flow of data (after the radio link is re-established).

Referring now toFIG. 3, a block diagram of a base station is illustrated showing some of the functional components that each base station may include in the arrangement ofFIG. 1. As shown, the base station includes for each of its one or more coverage areas an RF communication block80that includes a respective antenna arrangement82and transceiver84, a backhaul interface86, a processor88, and non-transitory data storage90, all of which may be communicatively linked together by a system bus, network, or other connection mechanism92.

The antenna arrangement82may include one or more antennas arranged in a manner now known or later developed for radiating to define a wireless coverage area. Typically, the antenna arrangement would be mounted at the top of an antenna tower. But the antenna arrangement can be provided in some other manner or location (such as in a small scale femtocell, for instance. Transceiver84, in turn, preferably comprises a power amplifier, modem chipset, channel cards, and other circuitry for sending and receiving communications via the antenna arrangement82in accordance with the agreed air interface protocol.

The backhaul interface86comprises a mechanism for communicatively linking the base station with core network entities (e.g., the MME and SGW described above). Thus, the backhaul interface86may provide a communication link interface between the base station and the core network entity. These communication links can be direct links or may include one or more intermediate nodes. For instances, under the LTE protocol, the core network entity can be an MME and the base stations can be eNodeBs, such that the backhaul interface86can be an S1-MME link interface. In any event, the backhaul interface86may take whatever form is necessary to couple with the communication links to the core network.

The processor88may include one or more general purposes processors (e.g., INTEL microprocessors) and/or one or more special purpose processors (e.g., dedicated digital signal processors or application specific integrated circuits). If the processor comprises multiple processors, the processors may work separately or in combination (e.g. in parallel). Further, the functions of the processor88can be integrated in whole or in part with the transceiver84or with one or more other aspects of the base stations.

The data storage90, in turn, may include one or more volatile and/or non-volatile storage components, such as magnetic, optical, or organic storage components, which can be integrated in whole or in part with the processor88. As shown, the data storage90may contain program logic94, which can be executed by the processor88to carry out certain base station functions described herein, for example, the functions described with reference toFIGS. 1,2A, and2B.

FIG. 4is a block diagram of the core network entity, for instance an MME, SGW, or PGW, showing some of the functional components that the core network entity may include in the arrangement ofFIG. 1. As shown, the core network entity may include a first backhaul interface100, a second backhaul interface102, a processor104, and non-transitory data storage106, all of which may be communicatively linked together by a system bus, network, or other connection mechanism108.

The first backhaul interface100functions to provide direct or indirect connectivity with base stations and particularly with the backhaul interface86of each base station, so as to facilitate communication of control signaling between the core network entity and each base station. As with the base station backhaul interface86, the first backhaul interface100of the core network entity may be arranged for wired and/or wireless backhaul communication and may take various forms depending on the links that connect the core network entity with each base station. For example, the first backhaul interface100may connect an MME with one or more S1-MME links to a plurality of eNodeBs. The first backhaul interface100may alternatively connect an SGW with one or more S1-links to a plurality of eNodeBs.

The second backhaul interface102functions to provide connectivity with other core network entities and/or with a transport network. For instance, if the core network entity is an MME, the second backhaul interface102may connect with a S11 link to an SGW. In another example, if the control node is a SGW, the second backhaul interface102may connect with a S5 or S8 link to a PGW, which in turn can provide connectivity with the transport network. Other examples are possible as well.

As with the base station processor90, the control node processor104may include one or more general purposes processors and/or one or more special purpose processors. The data storage106, in turn, may include one or more volatile and/or non-volatile storage components, such as magnetic, optical, or organic storage components, which can be integrated in whole or in part with the processor104. As shown, the data storage106may contain program logic110, which can be executed by the processor106to carry out various core network entity functions described herein.

An illustrative embodiment has been described above. It should be understood, however, that variations from the embodiment discussed are possible, while remaining within the true spirit and scope of the invention as claimed.

For example, the present disclosure has been discussed primarily in relation to an LTE network. However, other network architectures may also be used to implement the concepts disclosed herein. Illustratively, a CDMA network can also use different inactivity timers to separately manage radio links and core network links when a UE transitions between an idle state and an active state.