Abstract:
Briefly, in accordance with one or more embodiments, a handover of a wireless device from a first network to a second network may be implemented via operation of a single radio in the wireless device. A network architecture capable of implementing such a single radio handover operation may comprise a mobility management entity of a first network and an interworking function device capable of emulating an authenticator and/or protocol translation device of the first network or a second network. First switching logic is capable of exchanging information between the mobile station and the internetworking function device during a handover operation, and second switching logic is capable of exchanging information between the internetworking function device and an ASN, RNC, and/or SGSN of the target network.

Description:
BACKGROUND 
       [0001]    Mobile services providers typically may operate several heterogeneous access technologies and networks. Worldwide Interoperability for Microwave Access (WiMAX) is a wireless communication access technology intended to be deployed in accordance with the Institute of Electrical and Electronics Engineers (IEEE) standard referred to as IEEE 802.16. WiMAX is targeted to provide broadband wireless communication over longer distances. The initial WiMAX deployment may cover only limited areas of service that may already be currently serviced by the third generation (3G) type cellular networks, such as promulgated by the 3 rd  Generation Partnership Project (3GPP). For example, at least during initial deployment of WiMAX networks, islands of WiMAX coverage areas would exist within cellular 3G oceans. Hence, it may be useful for a 3G network service provider that deploys WiMAX services to converge WiMAX access and 3G access with seamless vertical mobility, or interaccess. Furthermore, dual mode devices that are capable of communicating with both 3G networks and WiMAX networks are expected to be deployed. 
         [0002]    Current solutions for network interaccess in 3GPP standards and the cellular industry utilize Layer 3 (L3) protocols (i.e., client-based Mobile IP) for providing mobility between access technologies. However, such client-based Mobile IP methods require simultaneous radio operation of both access technologies to execute a handover operation which may not be possible for the mobile platform to perform due to coexistence and/or interference issues between two heterogeneous wireless networks and radio equipment. Furthermore, client-based Mobile IP techniques may experience a great deal of latency in performing interaccess handovers, typically on the order of several seconds, that could hinder operation of real-time services such as Voice over Internet Protocol (VOIP) applications or the like. 
     
    
     
       DESCRIPTION OF THE DRAWING FIGURES 
         [0003]    Claimed subject matter is particularly pointed out and distinctly claimed in the concluding portion of the specification. However, such subject matter may be understood by reference to the following detailed description when read with the accompanying drawings in which: 
           [0004]      FIG. 1  is a block diagram of a wireless network illustrating a handover between two or more heterogeneous wireless networks in accordance with one or more embodiments; 
           [0005]      FIG. 2  is a block diagram of an architecture of a wireless network capable of handling a handover between another wireless network in accordance with one or more embodiments; 
           [0006]      FIG. 3  is a flow diagram of a method to implement a handover from a 3GPP type network to a WiMAX type network in accordance with one or more embodiments; and 
           [0007]      FIG. 4  is a flow diagram of a method to implement a handover from a WiMAX type network to a 3GPP type network in accordance with one or more embodiments. 
       
    
    
       [0008]    It will be appreciated that for simplicity and/or clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, if considered appropriate, reference numerals have been repeated among the figures to indicate corresponding and/or analogous elements. 
       DETAILED DESCRIPTION 
       [0009]    In the following detailed description, numerous specific details are set forth to provide a thorough understanding of claimed subject matter. However, it will be understood by those skilled in the art that claimed subject matter may be practiced without these specific details. In other instances, well-known methods, procedures, components and/or circuits have not been described in detail. 
         [0010]    In the following description and/or claims, the terms coupled and/or connected, along with their derivatives, may be used. In particular embodiments, connected may be used to indicate that two or more elements are in direct physical and/or electrical contact with each other. Coupled may mean that two or more elements are in direct physical and/or electrical contact. However, coupled may also mean that two or more elements may not be in direct contact with each other, but yet may still cooperate and/or interact with each other. For example, “coupled” may mean that two or more elements do not contact each other but are indirectly joined together via another element or intermediate elements. Finally, the terms “on,” “overlying,” and “over” may be used in the following description and claims. “On,” “overlying,” and “over” may be used to indicate that two or more elements are in direct physical contact with each other. However, “over” may also mean that two or more elements are not in direct contact with each other. For example, “over” may mean that one element is above another element but not contact each other and may have another element or elements in between the two elements. Furthermore, the term “and/or” may mean “and”, it may mean “or”, it may mean “exclusive-or”, it may mean “one”, it may mean “some, but not all”, it may mean “neither”, and/or it may mean “both”, although the scope of claimed subject matter is not limited in this respect. In the following description and/or claims, the terms “comprise” and “include,” along with their derivatives, may be used and are intended as synonyms for each other. 
         [0011]    Referring now to  FIG. 1 , a block diagram of a wireless network illustrating a handover between two or more heterogeneous wireless networks in accordance with one or more embodiments will be discussed. As shown in  FIG. 1 , wireless network  100  may comprise a WiMAX network coverage area  112  disposed in and/or proximate to a 2G/3G network coverage area  114 . WiMAX network coverage area  112  may be serviced by a WiMAX Base Station (WiMAX BS)  116 , and likewise 3G network coverage area  114  may be serviced by a 3GPP Radio Network Controller (3GPP RNC)  118 . Alternatively, for General Packet Radio Service (GPRS) access, 3GPP RNC  118  may include or comprise a Serving GPRS Support Node (SGSN). Other types of #G type services may likewise be implemented, for example Universal Mobile Telecommunications System (UMTS), High-Speed Downlink Packet Access (HSDPA), High-Speed Uplink Packet Access (HSUPA), 3GPP Long Term Evolution (3GPP LTE), and so on, although the scope of the claimed subject matter is not limited in this respect. 
         [0012]    In one or more embodiments, a mobile station (MS)  110  may move between WiMAX network coverage area  112  and 3G network coverage area  114 . If mobile station  110  moves from WiMAX coverage area  112  to 3G network coverage area  114 , or if mobile station  110  movies from 3G network coverage area  114  to WiMAX coverage area  112 , a handover operation  120  may occur between the WiMAX network to the 3G network, of from the 3G network to the WiMAX network. In one or more embodiments, handover operation  120  may implement an optimized handover method between WiMAX and 3GPP services where the mobile station  110  may have one radio active at any given time. To enable single radio operation that a single radio module of a multi-communication platform is on at any given time, inter-radio access technology (inter-RAT) info exchange may be utilized. An example architecture of a wireless network capable of implementing a handover between access services is discussed with respect to  FIG. 2 , below. 
         [0013]    Referring now to  FIG. 2 , a block diagram of an architecture of a wireless network capable of handling a handover between another wireless network in accordance with one or more embodiments will be discussed. In one particular embodiment,  FIG. 2  illustrates demonstrates architectural enhancements of a 3GPP Enhanced Packet Core (EPC)  200 . EPC is the architecture evolution of 3GPP systems being standardized as apart of 3GPP Release 8. It should be noted that not all of the components of 3GPP EPC  200  are illustrated in  FIG. 2 , and that  FIG. 2  shows the components involved for vertical handover with a WiMAX network. In one or more embodiments, a WiMAX Internetworking Function (WiMAX IWF) is added to Mobility Management Entity (MME)  218  of 3GPP network  200 . Alternatively, WiMAX IWF  218  may be disposed outside, or at least partially outside, of the MME  218 . WiMAX IWF  218  is capable of emulating the function of WiMAX access service network (ASN)  226  for handovers  120  from 3GPP services to WiMAX services. Likewise, WiMAX IWF  218  is capable of emulates the function of the Radio Network Controller (RNC) or Serving GPRS Support Node (SGSN)  214  in handovers from WiMAX services to 3GPP services. Furthermore, two interfaces are utilized to facilitate the processes involved in handover  120 . In one or more embodiments, switch SW 1   232  comprises a logical interface between the mobile station and/or user equipment (UE/MS)  110  and WiMAX IWF  218  for handover related communication. Likewise, switch SW 2   234  is utilized for exchange of information of context between WiMAX IWF  218  and WiMAX ASN  226 . In one or more embodiments, the interface implemented by switch SW 2   234  may be based on a WiMAX inter-ASN (WiMAX R4) interface, although the scope of the claimed subject matter is not limited in this respect. To complete 3GPP network  200 , SGSN  214  couples to GSM EDGE Radio Access Network (GERAN)  210  and to UMTS Terrestrial Radio Access Network (UTRAN)  212 . User equipment and/or mobile station  110  couples to evolved-UTRAN (E-UTRAN)  222  which in turn couples to serving gateway  224 . Serving gateway  224  couples to public data network gateway (PDN Gateway)  228  which is coupled with Internet Protocol Services (IP Services)  230  to allow user equipment and/or mobile station  110  to connect to the internet, although the scope of the claimed subject matter is not limited in this respect. 
         [0014]    Referring now  FIG. 3 , a flow diagram of a method to implement a handover from a 3GPP type network to a WiMAX type network in accordance with one or more embodiments will be discussed. It should be noted that the method  300  as shown in  FIG. 3  represents one particular procedure for implementing a handover  120  between two access technologies such as between a WiMAX network and a 3GPP network or the like, however other variations of method  300  may be implemented with more or fewer procedures than shown in  FIG. 3 , and/or in a different order of the procedures, and the scope of the claimed subject matter is not limited in this respect. Furthermore, it should be noted that the procedures shown in  FIG. 3  with dashed lines are optional and may or may not be implemented in some applications. In one or more embodiments, at procedure  310  3GPP connected user equipment and/or mobile station (UE/MS)  110  performs network discovery and determines that WiMAX access is available in present coverage area  112 . At procedure  314 , a decision is made to perform a vertical handover  120  to WiMAX services. The decision for handover  120  may be made by UE/MS  110 , by the source 3GPP network  114 , and/or assisted either way, although the scope of the claimed subject matter is not limited in this respect. At procedure  316 , an IKEv2 procedure may be initiated by the UE/MS  110 . In this procedure, the UE/MS  110  may be authenticated using an Extensible Authentication Protocol (EAP)-Authentication and Key Agreement (AKA) method. WiMAX IWF  218  functions as the EAP authenticator and generates the key derivates that are involved. At or near the end of procedure  316 , an IPSec tunnel may be set up between the UE/MS  110  and WiMAX IWF  218  for secure communication. 
         [0015]    Optionally an explicit handover request is sent at procedure  318  to from the WiMAX IWF  218  to UE/MS  110  or vice versa. Such an explicit handover request message may be useful if the Internet Protocol Security (IPSec) tunnel between UE/MS  110  and WiMAX IWF  218  remains open. In this message, the details of the target WiMAX BS  116  context can be sent. After procedure  316 , UE/MS  110  is aware of the target WiMAX BS  116  and it can start downlink synchronization (WiMAX DL Sync) to the target WiMAX BS  166  in the 3GPP idle periods at procedure  319 . At procedure  320 , WiMAX IWF  218  determines the correct target WiMAX ASN  226  based at least in part on the address of the target WiMAX BS  116 . Subsequently, WiMAX IWF  218  sends the message of a WiMAX R4 Handover Request to the Target WiMAX ASN  226 . Upon receipt of the message, Target WiMAX ASN  226  may request further context of US/MS  110  by sending a WiMAX R4 Context Request at procedure  322 . WiMAX IWF  218  responds at procedure  324  to the context request by including the detailed context of the UE/MS  110  in the message WiMAX R4 Context Response. At procedure  326 , Target WiMAX ASN  226  prepares radio resources and sets up a data path, and at procedure  328 , a Gateway of the Target WiMAX ASN  226  starts Proxy Mobile IP Protocol (PMIP) tunneling by sending a Proxy Binding Update to PDN Gateway (PDN GW)  228  which acts as the Mobile IP Home Agent (HA). The PDN GW  228  responds with Proxy Binding Acknowledgement to the Gateway of the Target WiMAX ASN  226 , which includes IP address for the UE/MS  100 , which may be the same IP address that was allocated to the 3GPP connection for the present UE/MS  110 . 
         [0016]    In one or more embodiments, Target WiMAX ASN  226  informs WiMAX IWF  218  of WiMAX preparation completion by sending WiMAX R4 Handover Response at procedure  332 . WiMAX IWF  218  acknowledges completion of WiMAX resource reservation at procedure  332  by sending WiMAX R4 Handover Acknowledgement. At procedure  336 , WiMAX IWF  218  commands the UE/MS  110  to switch to WiMAX services. Relevant configuration information may be sent to the UE/MS in this message. At procedure  338 , UE/MS  110  starts the uplink synchronization process and/or related procedures related to a WiMAX optimized handover, and then 3GPP resources are released at procedure  338  anytime after completion of the handover command executed at procedure  336 . Likewise, the IPSec tunnel of procedure  316  may be shut down after completion of handover  120 , although the scope of the claimed subject matter is not limited in this respect. In one or more embodiments, method  300  of  FIG. 3  may be executed in less than 50 milliseconds, although the scope of the claimed subject matter is not limited in this respect. 
         [0017]    Referring now to  FIG. 4 , a flow diagram of a method to implement a handover from a WiMAX type network to a 3GPP type network in accordance with one or more embodiments will be discussed. The method  400  shown in  FIG. 4  is similar to method  300  of  FIG. 3  except the handover  120  occurs from WiMAX network  112  to 3GPP network  114 . It should be noted that the method  400  as shown in  FIG. 4  represents one particular procedure for implementing a handover  120  between two access technologies such as between a WiMAX network and a 3GPP network or the like, however other variations of method  400  may be implemented with more or fewer procedures than shown in  FIG. 4 , and/or in a different order of the procedures, and the scope of the claimed subject matter is not limited in this respect. Furthermore, it should be noted that the procedures shown in  FIG. 4  with dashed lines are optional and may or may not be implemented in some applications. At procedure  410 , the WiMAX connected user equipment and/or mobile station (UE/MS)  110  performs network discovery and determines that 3GPP access services are available in the present coverage area. At procedure  412 , a decision is made to perform a vertical handover  120  to 3GPP services. This decision can be made by the ULE/MS  110 , by WiMAX network  112 , and/or assisted either way, although the scope of the claimed subject matter is not limited in this respect. In one or more embodiments, an IKEv2 process is initiated at procedure  414  by UE/MS  110 . During this procedure, UE/MS  110  may be is authenticated using an Authentication and Key Agreement (AKA) method, although the scope of the claimed subject matter is not limited in this respect. WiMAX IWF  218  functions as the authenticator for SGSN  214  and generates the key derivates are involved. At the end of procedure  414 , an IPSec tunnel may be set up between the UE/MS  110  and WiMAX IWF  218  for secure communication. 
         [0018]    Optionally in one or more embodiments, an explicit handover request is sent at procedure  416  from WiMAX IWF  218  to UE/MS  110  or vice versa. Such a message may be useful if the IPSec tunnel between UE/MS  110  and the WiMAX IWF  218  remains open. In this message, the details of context of the target SGSN  214  can be sent. After procedure  416 , UE/MS  110  is aware of the target SGSN  214 , and UE/MS  110  can start downlink synchronization to the target SGSN  214  in WiMAX idle periods. At procedure  418  the handover to 3GPP network  114  optionally may be initiated by the WiMAX network  112  and/or by UE/MS  110  in which case an R4 WiMAX Handover Request is sent from WiMAX ASN  226  to WiMAX IWF  218 . At procedure  420 , the rest of a 3GPP attach procedure between UE/MS  110  and WiMAX IWF  218  may be performed. At procedure  422 , WiMAX IWF  218  determines the correct target SGSN  214  based at least in part on the address target 3GPP RNC  118 . Subsequently, WiMAX IWF  218  sends the message of Forward Relocation Request to the target SGSN  214 . At procedure  424 , the target SGSN  214  prepares the radio resources of the target 3GPP network  1124  and sets up a data path. At procedure  426 , the target SGSN  214  sends the a Forward Relocation Response to the WiMAX IWF  218 , and in response WiMAX IWF  218  triggers the data path establishment at procedure  428  by sending Create Default Bearer Request (REQ). It should be noted that procedure  428  may be optionally implemented and in some embodiments procedure  428  may not be implemented. The Serving Gateway  224  starts the Proxy Mobile IP Protocol (PMIP) tunneling at procedure  430  by sending a Proxy Binding Update to PDN GW  228  which acts as the Mobile IP Home Agent (HA). In the case of GPRS Tunneling Protocol (GTP), Create Bearer Request is sent by the PDN GW  228 . PDN GW  228  responds at procedure  432  with Proxy Binding Acknowledgement to the Serving Gateway  224  which includes IP address for UE/MS  110  which may be the same IP address that was allocated to the 3GPP connection for the present MS/UE  110 . In the case of GTP, Create Bearer Response is sent by the PDN GW  228 . At procedure  434 , Serving GW  224  responds to WiMAX IWF  218  by a Create Default Bearer Response which indicates the completion of the data path. 
         [0019]    In one or more embodiments, at procedure  436  WiMAX IWF  218  commands UE/MS  110  to switch to 3GPP network  114 . Relevant configuration information may be sent to the UE/MS  110  in this message. At procedure  438 , UE/MS  110  sends a Handover Complete message to the target 3GPP network  114 . In the event procedure  418  is executed, WiMAX IWF  218  may respond to WiMAX ASN  226  about the completion of handover procedures via a WiMAX R4 Handover Response. In such a case WiMAX ASN  226  confirms the handover completion by via a WiMAX R4 Handover Acknowledgment (Ack). WiMAX resources may be released anytime after execution of procedure  440 . Furthermore, the IPSec tunnel set up during procedure  414  may be taken down after completion of the handover. In one or more embodiments, method  400  of  FIG. 4  may be executed in less than 50 milliseconds, although the scope of the claimed subject matter is not limited in this respect. 
         [0020]    Although the claimed subject matter has been described with a certain degree of particularity, it should be recognized that elements thereof may be altered by persons skilled in the art without departing from the spirit and/or scope of claimed subject matter. It is believed that the subject matter pertaining to a wireless network handover with single radio operation and/or many of its attendant utilities will be understood by the forgoing description, and it will be apparent that various changes may be made in the form, construction and/or arrangement of the components thereof without departing from the scope and/or spirit of the claimed subject matter or without sacrificing all of its material advantages, the form herein before described being merely an explanatory embodiment thereof, and/or further without providing substantial change thereto. It is the intention of the claims to encompass and/or include such changes.