Abstract:
Embodiments of a wireless access network and methods for relocating a foreign agent (FA) for an idle mode mobile station (MS) in a proxy mobile internet protocol (PMIP) enabled access service network (ASN) are described herein. In some embodiments, the relocation of the FA is triggered by either an anchor paging controller or a paging controller of a target ASN when the idle mode mobile stations moves across ASNs.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/419,455, filed on May 19, 2006, which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    Some embodiments of the present invention pertain to wireless access networks. Some embodiments pertain to relocating a foreign agent (FA) for an idle mode mobile station (MS) in a proxy mobile internet protocol (PMIP) enabled access service network (ASN). Some embodiments pertain to PMIP operations of idle mode mobile stations in accordance with one of the IEEE 802.16 standards. 
       BACKGROUND 
       [0003]    Wireless access networks can be used to communication voice data, such as voice over internet protocol (VoIP), as well other time-sensitive traffic flows, with mobile terminals. These wireless access networks need to quickly determine the current location of a mobile terminal to meet the requirements of the traffic flow. During active mode, the locations of mobile terminals are updated and maintained by a home agent in the network. However when mobile terminals are in idle mode, their locations are not continually updated. For some time-sensitive applications, the delay associated with locating a mobile terminal in idle mode may be excessive. 
         [0004]    Thus, there are general needs for wireless access networks and methods for handover that allow a mobile station in idle mode to be located easier. There are also general needs for wireless access networks that can page a mobile terminal for time-sensitive applications, such as VoIP and push-to-talk (PTT) applications, without excessive delay when the mobile terminal is in idle mode. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  illustrates a wireless communication network in accordance with some embodiments of the present invention; 
           [0006]      FIG. 2  illustrates an idle mode handover procedure in accordance with some embodiments of the present invention; and 
           [0007]      FIG. 3  illustrates a block diagram of a paging controller in accordance with some embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    The following description and the drawings sufficiently illustrate specific embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments of the invention set forth in the claims encompass all available equivalents of those claims. Embodiments of the invention may be referred to herein, individually or collectively, by the term “invention” merely for convenience and without intending to limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed. 
         [0009]      FIG. 1  illustrates a wireless communication network in accordance with some embodiments of the present invention. Wireless communication network  100  may include core service network  102  and a plurality of access service networks  104 , shown as access service network  104 A, access service network  104 B, access service network  104 C and access service network  104 D. Access service networks  104  route communications between core service network  102  and mobile stations, such as mobile station  112 , allowing mobile stations, such as mobile station  112 , to receive communications from external networks  106  and to send communications to external networks  106 . 
         [0010]    Each access service network  104  may include foreign agent  114  and paging controller  116  for communicating with other access service networks and/or communicating with core service network  102 . Access service networks  104  may also include base stations for communicating radio-frequency signals with the mobile stations, such as mobile station  112 . Each of the base stations may be associated with one of paging groups (PGs)  110 . Paging groups  110  may comprise a cluster of base stations and may be administered by an associated one of paging controllers  116 . 
         [0011]    In some embodiments, some access service networks  104 , such as access service network  104 A, may include proxy mobile client  120 . Proxy mobile client  120  may serve as a proxy for mobile station  112  and may perform certain network operations on behalf of mobile station  112 . These embodiments are discussed in more detail below. Although proxy mobile client  120  is illustrated in access service network  104 A, any of access service networks  104  may include one or more proxy mobile clients for mobile stations serviced by access service networks  104 . 
         [0012]    In some embodiments, access service networks  104  may include an access service network gateway (not separately illustrated) for communicating with core service network  102 . Each access service network gateway may include a foreign agent, such as one of foreign agents  114 , a paging controller, such as one of paging controllers  116  and/or a proxy mobile client, such as proxy mobile client  120 . In some embodiments, one or more of the functional elements of an access service network gateway may be distributed among the various physical entities, although the scope of the invention is not limited in this respect. 
         [0013]    Core service network  102  may include home agent  118  and authentication, accounting, and administration (AAA) server  122 . Home agent  118  may store an internet protocol (IP) address of foreign agent  114  of access service network  104  where mobile station  112  is currently located. In this way, data  101  destined for mobile station  112  that is received at core service network  102  may be routed to the proper one of access service networks  104  based on the information in home agent  118 . 
         [0014]    In accordance with some embodiments, mobile station  112  may operate in either active mode or idle mode. During active mode, mobile station  112  may be actively communicating within one of access service networks  104 . During idle mode, mobile station  112  may be in a lower-power state and may be listening for pages and/or broadcast channels within one of access service networks  104 . During active mode, the IP address of mobile station  112  with respect to each of access service networks  104  may be updated and maintained by home agent  118 . In active mode, the location of mobile station  112  with respect to a particular base station within one of paging groups  110  may also be known because mobile station  112  may be actively engaging in communications through the base station. However in conventional networks, the location of mobile station  112  with respect to access service networks  104  may not be known when mobile station  112  is in idle mode because mobile station  112  may not be actively engaging in communications. When mobile station  112  changes access service networks  104 , the IP address of mobile station  112  may need to be changed or updated. 
         [0015]    During idle mode, mobile station  112  may receive an incoming message, such as a page, to indicate to mobile station  112  that there is data for mobile station  112  or that there is an incoming call for mobile station  112 . In response to the page, mobile station  112  may transition from idle mode to active mode to receive and to process the data. The use of an updated IP address for mobile station  112  while in idle mode may allow paging and connection establishment latency to be reduced, although the scope of the invention is not limited in this respect. This may help support the requirements for time-sensitive applications such as VoIP and PTT. 
         [0016]    In accordance with some embodiments, mobile station  112  may not necessarily have the capability to perform certain network operations, such as mobile internet protocol (MIP) registration request and MIP registration response operations, for updating its IP address as it changes between paging groups  110  of different access service networks  104 . In these embodiments, proxy mobile client  120  may serve as a proxy for mobile station  112  and may perform certain network operations, such as MIP registration request and MIP registration response operations, on behalf of mobile station  112 . In these embodiments, the infrastructure of network  100  may be proxy mobile IP (PMIP) based and proxy mobile client  120  may be a PMIP client for mobile station  112 , although the scope of the invention is not limited in this respect. 
         [0017]    In some embodiments, the infrastructure of network  100  may also support client mobile IP (CMIP) operations, although the scope of the invention is not limited in this respect. In these embodiments that support CMIP operations, some mobile stations may have capability to perform MIP registration request and MIP registration response operations, although the scope of the invention is not limited in this respect. 
         [0018]    In accordance with some embodiments, a handover for mobile station  112  may occur when mobile station  112  reaches a new paging group  110  while mobile station  112  is in idle mode. In the examples discussed herein, an anchor paging controller, illustrated as anchor paging controller  116 B, may refer to the paging controller  116  of the access service network  104  where mobile station  112  was last registered, and a relay paging controller, illustrated as relay paging controller  116 D, may refer to a paging controller  116  of an access service network  104  where mobile station  112  may have relocated. In these embodiments, a location update message may be sent to relay paging controller  116 D within access service network  104 D where mobile station  112  now resides. In these embodiments, the location update message may include the network address of anchor paging controller  116 B. Relay paging controller  116 D may contact anchor paging controller  116 B to inform anchor paging controller  116 D that mobile station  112  has changed locations while in idle mode. In these embodiments, anchor paging controller  116 B may maintain the latest location information for mobile station  112  (e.g., in terms of one of paging groups  110 ) while mobile station  112  is in idle mode. 
         [0019]    When anchor paging controller  116 B receives a location update request message from relay paging controller  116 D, it may compare the address of relay paging controller  116 D it received in the message with the address of the last paging controller  116  that it had stored in its location register for mobile station  112 . If the two addresses match, then mobile station  112  has switched paging groups  110  within the same access service network  104 . In this situation, no action is needed to update the location information for mobile station  112 . In this situation anchor paging controller  116 B and relay paging controller  116 D may be the same paging controller within the same access service network. 
         [0020]    When the addresses are different, then anchor paging controller  116 B determines that mobile station  112  has switched to a new paging group, such as paging group  110 D in access service network  104 D. In this situation, a handover procedure may be performed without the knowledge of the mobile station  112 , to update its foreign to foreign agent  114  of the access service network  104 D where mobile station  112  is now located. An example of a handover procedure for a mobile station operating in idle mode is described below. 
         [0021]    In accordance with some embodiments, paging and data path establishment for mobile station  112  may occur quicker when mobile station  112  exits idle mode. As a result, the overall paging and network re-entry latency may be reduced. Furthermore, the network resources used to perform data path setup when mobile station  112  is to exit idle mode may be reduced and a shorter data path may be maintained between mobile station  112  and home agent  118  during idle mode. 
         [0022]      FIG. 2  illustrates an idle mode handover procedure in accordance with some embodiments of the present invention. Idle mode handover procedure  200  may be performed to maintain a current IP address of a mobile station, such as mobile station  112  ( FIG. 1 ), that is in idle mode as the mobile station changes its location between paging groups  110  ( FIG. 1 ) of different access service network  104  ( FIG. 1 ). In  FIG. 2 , home agent  118  may correspond to home agent  118  ( FIG. 1 ), relay paging controller (PC)  116 D may correspond to relay paging controller  116 D ( FIG. 1 ), target foreign agent  114  may correspond to foreign agent  114  ( FIG. 1 ), anchor paging controller  116 B may correspond to anchor paging controller  116 B ( FIG. 1 ) and proxy mobile client  120  may correspond to proxy mobile client  120  ( FIG. 1 ). 
         [0023]    Referring to  FIGS. 1 and 2 , after mobile station  112  changes location between paging groups  110 , location update request message  201  may be received from relay paging controller  116 D at anchor paging controller  116 B. Anchor paging controller  116 B may determine whether mobile station  112  has switched access service networks  104  based on a network address of relay paging controller  116 D. When mobile station  112  has switched between access service networks  104 , handover request message  203  may be sent to proxy mobile client  120  of mobile station  112  to indicate a network address of target foreign agent  114  for use when routing subsequent communications to mobile station  112 . 
         [0024]    In some embodiments, the network address of relay paging controller  116 D may be received by anchor paging controller  116 B in location update request message  201 . In some embodiments, location update request message  201  may be sent from relay paging controller  116 D when mobile station  112  has changed its location from prior paging group  110 B to new paging group  110 D, although the scope of the invention is not limited in this respect. 
         [0025]    In some embodiments, anchor paging controller  116 B may determine whether mobile station  112  has either switched paging groups  110  within current access service network  104 B or switched paging groups  110  to a new access service network, such as access service network  104 C or access service network  104 D, by comparing the network address of the relay paging controller received in location update request message  201  with a network address of a paging controller stored in a location register of anchor paging controller  116 B, although the scope of the invention is not limited in this respect. 
         [0026]    In some embodiments, handover request message  203  may be sent if the network address of relay paging controller  116 D received in location update request message  201  is different from the network address of the paging controller stored in the location register of anchor paging controller  116 B. In some embodiments, handover request message  203  may be sent from anchor paging controller  116 B to proxy mobile client  120  of mobile station  112 . In some embodiments, handover request message  203  may include a network address of target foreign agent  114 . In some embodiments, target foreign agent  114  and relay paging controller  116 D may be associated with access service network  104 D, although the scope of the invention is not limited in this respect. 
         [0027]    In some embodiments, anchor paging controller  116 B may refrain from sending handover request message  203  to proxy mobile client  120  if the network address of relay paging controller  116 D received in location update request message  201  matches the network address of the paging controller stored in the location register of anchor paging controller  116 B. In these embodiments, the matching addresses may indicate that mobile station  112  has changed paging groups  110  of paging controller  116 B of current access service network  104 B, although the scope of the invention is not limited in this respect. 
         [0028]    In some embodiments, proxy mobile client  120  may send handover response message  205  in response to handover request message  203 . In these embodiments, handover response message  205  may indicate that the handover request message  203  was successfully received, although the scope of the invention is not limited in this respect. In some embodiments, proxy mobile client  120  may send registration request message  207  in response to receipt of handover request message  203  to target foreign agent  114 . Registration request message  207  may instruct target foreign agent  114  to register the mobile station  112  as being associated with home agent  118  and anchor paging controller  116 B, although the scope of the invention is not limited in this respect. 
         [0029]    In some embodiments, in response to receiving registration request message  207  from proxy mobile client  120 , target foreign agent  114  may send registration request message  209  to home agent  118 . In these embodiments, registration request message  209  may include an IP address of target foreign agent  114 . Home agent  118  may store the IP address of target foreign agent  114  for mobile station  112  for use in routing the subsequent communications to mobile station  112 , although the scope of the invention is not limited in this respect. 
         [0030]    In some embodiments, home agent  118  may send registration response message  211  to target foreign agent  114  in response to receipt of the registration request message  209 . Target foreign agent  114  may send registration response message  213  to proxy mobile client  120  to indicate that home agent  118  has been updated with the IP address of target foreign agent  114 , although the scope of the invention is not limited in this respect. 
         [0031]    In some embodiments, proxy mobile client  120  may send handover confirmation message  215  to anchor paging controller  116 B to indicate that handover of mobile station  112  in idle mode has been successfully completed and that a prior foreign agent, such as foreign agent  114 B, is no longer a current foreign agent for mobile station  112 , although the scope of the invention is not limited in this respect. 
         [0032]    In some embodiments, the network address of relay paging controller  116 D may be in either in a header (e.g., the source IP address) or a body of location update request message  201 , although the scope of the invention is not limited in this respect. 
         [0033]    In some embodiments, mobile station  112  may be a mobile IP terminal associated with proxy mobile client  120  and proxy mobile client  120  may send mobile internet-protocol (MIP) registration request (RRQ) and MIP registration response (RRP) messages on behalf of mobile station  112  (i.e., for re-anchoring) when mobile station  112  changes paging groups  110 . In these embodiments, proxy mobile client  120  may perform at least some network operations (e.g., sending the MIP RRP and RRQ messages) on behalf of mobile station  112 , although the scope of the invention is not limited in this respect. 
         [0034]    The use of proxy mobile client  120  does not involve a change in the point of attachment address when a mobile station moves allowing mobile station  112  to operate without an MIP stack. In these embodiments, mobile station  112  may be a mobile internet protocol IP terminal without capability to send the MIP RRP and RRQ messages when it changes location. In these embodiments, mobile station  112  may rely on proxy mobile client  120  to perform these network operations, although the scope of the invention is not limited in this respect. 
         [0035]    In some embodiments, when mobile station  112  changes locations between paging groups  110  when in idle mode, mobile station  112  may send a ranging request (RNG-REQ) message to relay paging gateway  116 B through a base station of the new paging group  110 . Mobile station  112  may identify the new paging group  110  based on a paging group identifier (PG-ID) that may be broadcasted by the base stations of the new paging group  110 . In response to the ranging request message, relay paging gateway  116 D may send location update request message  201  to anchor paging controller  116 B as previously discussed. After registration response message  213  is sent to proxy mobile client  120 , a ranging response (RNG-RESP) message may be sent to mobile station  112 , although the scope of the invention is not limited in this respect. The ranging response message may indicate that the location update was successfully registered at the location register of paging controller  116 D. 
         [0036]    In active mode, on the other hand, mobile station  112  ranging request messages are not sent by mobile station  112  when it crosses a paging group boundary because mobile station  112  may be tracked at the base-station level of granularity. 
         [0037]    In some embodiments, proxy mobile client  120  for mobile station  112  may be located within first access service network  104 A, and anchor paging controller  116 B may be located within a second access service network  104 B. Relay paging controllers, such as relay paging controller  110 C or relay paging controller  116 D, may be located within either third or fourth access service network  104 C or  104 D respectively. In these embodiments, second access service network  104 B may be a prior access service network, and either a third access service network  104 C or fourth access service network  104 D may be a new access service network for mobile station  112 , although the scope of the invention is not limited in this respect. 
         [0038]    In some embodiments, at least some of access service networks  104  may comprise broadband wireless access (BWA) networks, such as WiMax networks, that communicate with a plurality of mobile stations using a multiple-access technique, such as orthogonal frequency division multiple access (OFDMA). In some embodiments, mobile station  112  may be a broadband wireless access network mobile terminal, although the scope of the invention is not limited in this respect. 
         [0039]    In some embodiments, data  101  destined for the mobile station  112  may be received at core service network  102  and may be routed to one of the access service networks  104  based on the IP address stored in home agent  118  for mobile station  112 . In some embodiments, at least some of data  101  may comprise voice-over IP data. In some embodiments, mobile station  112  may be operable in a push-to-talk mode, although the scope of the invention is not limited in this respect. In some embodiments, data  101  may comprise a paging or data-path establishment message directed to mobile station  112 , although the scope of the invention is not limited in this respect. 
         [0040]      FIG. 3  illustrates a block diagram of a paging controller in accordance with some embodiments of the present invention. Paging controller  300  may be suitable for use as any one of paging controllers  116  ( FIG. 1 ). In some embodiments, paging controller  300  may be suitable for anchor paging controller  116 B ( FIG. 1 ), although the scope of the invention is not limited in this respect. Paging controller  300  may include network interface circuitry  302 , processing circuitry  304  and location register  306 . Paging controller  300  may also include other functional elements not illustrated. 
         [0041]    In accordance with some embodiments, network interface circuitry  302  may receive a location update request message, such as location update request message  201  ( FIG. 2 ) from a relay paging controller, such as relay paging controller  116 D ( FIG. 1 ) when a mobile station, such as mobile station  112  ( FIG. 1 ) has changed paging groups  110  ( FIG. 1 ). Location register  306  may store a network address of paging controller  300 . Processing circuitry  304  may determine whether mobile station  112  ( FIG. 1 ) has switched access service networks  104  ( FIG. 1 ) by comparing a network address of a relay paging controller received in location update request message  201  ( FIG. 2 ) with a network address of paging controller  300  stored in location register  306 . 
         [0042]    In some embodiments, when processing circuitry  304  determines that mobile station  112  ( FIG. 1 ) has switched between access service networks  104  ( FIG. 1 ), network interface circuitry  302  may send handover request message  203  ( FIG. 2 ) to proxy mobile client  120  ( FIG. 1 ) to indicate the address of the target foreign agent, such as foreign agent  114  ( FIG. 1 ), for use when routing subsequent communications to mobile station  112  ( FIG. 1 ). In these embodiments, paging controller  300  may be operating as anchor paging controller  116 B. 
         [0043]    In some embodiments, the handover request message  203  may be sent by network interface circuitry  302  if the network address of the relay paging controller received in location update request message  201  is different from the network address of the anchor paging controller stored in location register  306 . In some embodiments, network interface circuitry  302  may refrain from sending handover request message  203  ( FIG. 2 ) to proxy mobile client  120  if the network address of the relay paging controller received in location update request message  201  ( FIG. 2 ) matches the network address of the anchor paging controller stored in location register  306 . 
         [0044]    Although paging controller  300  is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, application specific integrated circuits (ASICs), and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements of paging controller  300  may refer to one or more processes operating on one or more processing elements. 
         [0045]    In some embodiments, mobile station  112  ( FIG. 1 ) may communicate orthogonal frequency division multiplexed (OFDM) communication signals over a multicarrier communication channel. The multicarrier communication channel may be within a predetermined frequency spectrum and may comprise a plurality of orthogonal subcarriers. In some embodiments, the multicarrier signals may be defined by closely spaced OFDM subcarriers. In some of these embodiments, mobile station  112  ( FIG. 1 ) may communicate in accordance with a multiple access technique, such as orthogonal frequency division multiple access (OFDMA), although the scope of the invention is not limited in this respect. In some embodiments, mobile station  112  may be part of a wireless communication device that may communicate using spread-spectrum signals, although the scope of the invention is not limited in this respect. 
         [0046]    In some embodiments, mobile station  112  ( FIG. 1 ) may be a broadband wireless access (BWA) network communication station, such as a Worldwide Interoperability for Microwave Access (WiMax) communication station, although the scope of the invention is not limited in this respect. In some embodiments, mobile station  112  ( FIG. 1 ) may be a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wirelessly. In some BWA network embodiments, the frequency spectrum for the signals communicated by mobile station  112  ( FIG. 1 ) may comprise frequencies between 2 and 11 gigahertz (GHz), although the scope of the invention is not limited in this respect. 
         [0047]    In some embodiments, mobile station  112  ( FIG. 1 ) may communicate in accordance with specific communication standards, such as the Institute of Electrical and Electronics Engineers (IEEE) standards including the IEEE 802.16-2004 and the IEEE 802.16(e) standards for wireless metropolitan area networks (WMANs) including variations and evolutions thereof, although the scope of the invention is not limited in this respect as they may also be suitable to transmit and/or receive communications in accordance with other techniques and standards. For more information with respect to the IEEE 802.16 standards, please refer to “IEEE Standards for Information Technology—Telecommunications and Information Exchange between Systems” Metropolitan Area Networks—Specific Requirements—Part 16: “Air Interface for Fixed Broadband Wireless Access Systems,” May 2005 and related amendments/versions. 
         [0048]    Unless specifically stated otherwise, terms such as processing, computing, calculating, determining, displaying, or the like, may refer to an action and/or process of one or more processing or computing systems or similar devices that may manipulate and transform data represented as physical (e.g., electronic) quantities within a processing system&#39;s registers and memory into other data similarly represented as physical quantities within the processing system&#39;s registers or memories, or other such information storage, transmission or display devices. Furthermore, as used herein, a computing device includes one or more processing elements coupled with computer-readable memory that may be volatile or non-volatile memory or a combination thereof. 
         [0049]    Some embodiments of the invention may be implemented in one or a combination of hardware, firmware and software. Some embodiments of the invention may also be implemented as instructions stored on a computer-readable storage medium, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage medium may include any tangible mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable medium may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other tangible mediums. 
         [0050]    The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. 
         [0051]    In the foregoing detailed description, various features are occasionally grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, invention may lie in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment.