Patent Application
20080096560
A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:
This invention provides a method, system and apparatus for facilitating and ensuring handoffs across heterogeneous networks.
Referring now to the drawing figures in which like reference designators refer to like elements, there is shown in
The WLAN network 12 includes a distribution network 26 (nonsecure) for connecting the AP nodes 28 to an access controller (“AC”) 24. The AC 24 functions to provide secure access to the backbone network 22 from the WLAN medium (e.g., distribution network 26 and AP nodes 28), mobility management, and configuration management of the AP nodes 28. The backbone network 22 is a secure network and provides connectivity between the interfacing networks, such as the Internet 16, and the distribution network 26. The authentication, authorization and accounting (“AAA”) server 20 provides the authentication, authorization and accounting in the WLAN Wi-Fi domain.
In general, authentication refers to the confirmation that a user who is requesting services is a valid user of the network services requested. Authentication is accomplished via the presentation of an identity and credentials. Examples of types of credentials include one-time tokens, passwords, digital certificates and telephone numbers (calling/called). Authorization typically refers to the granting of specific types of service (including “no service”) to a user, based on their authentication, what services they are requesting, and the current system state. Authorization may be based on restrictions, for example time-of-day restrictions, or physical location restrictions, or restrictions against multiple logins by the same user, and it determines the nature of the service to be granted to a user. Examples of types of service include, but are not limited to: IP address filtering, address assignment, route assignment, QoS services, bandwidth control, traffic management, encryption (decryption) and tunneling to a specific endpoint.
In general, accounting refers to the tracking of the consumption of network resources by users. This information may be used for management, planning, billing, or other purposes. Typical information that is gathered in accounting is the identity of the user, the nature of the service delivered, when the service began, and when it ended.
The WLAN network 12 further includes a firewall 18 which is generally defined as a piece of hardware and/or software that functions in a networked environment to prevent some communications forbidden by a security policy. A firewall may sometimes be referred to as a border protection device (“BPD”) or packet filter and it has the basic task of controlling traffic between different zones of trust. These typical zones of trust include the Internet (which is a zone with no trust) and an internal network (which is a zone with high trust). The ultimate goal is to provide controlled connectivity between zones of differing trust levels through the enforcement of a security policy and connectivity model based on the least privilege principle.
Continuing to refer to
The IP RAN network 14 further includes a packet data interworking function (“PDIF”) 32 which acts as the gateway into the core network 34 and the packet data services domain of the back-haul network 36, e.g., where the network is a code division multiple access (“CDMA”) or cdma2000 technology. The PDIF 32 may include mobile Internet protocol (“MIP”) foreign agent (“FA”) functionality for MIP version 4 (“MIPv4”) and MIP version 6 (“MIPv6”) access. MIP is an Internet Engineering Task Force (“IETF”) standard communications protocol that is designed to allow mobile user device 30 to move from one network to another while maintaining its permanent IP address. The PDIF 32 may implement end-to-end secure tunnel management procedures between itself and the mobile user device 30, including establishment and release of a tunnel (via a tunneling protocol such as IP security (“IPSec”)).
The PDIF 32 may also provide allocation of an IP address to the mobile user device 30 from the operator's network, e.g., the cdma2000 network, and provide for the encapsulation and de-capsulation of traffic to and from the mobile user device 30, as well as enforcing the operator's policies such as packet filtering and routing. For example, the operator's policies may provide for different restrictions on network access based on certain times or days, or on whether the employee is a member of management. In addition, the PDIF 32 may also support user (e.g., mobile user device 30) authentication and transfer of authorization policy though the interface to the home AAA (“H-AAA”).
The mobile user device 30 may include a wide range of portable electronic devices, including but not limited to mobile phones, personal data assistants (“PDA”) and similar devices, which use the various communication technologies such as advanced mobile phone system (“AMPS”), time division multiple access (“TDMA”), code division multiple access (“CDMA”), global system for mobile communications (“GSM”), general packet radio service (“GPRS”), 1× evolution-data optimized (abbreviated as “EV-DO” or “1×EV-DO”) and universal mobile telecommunications system (“UMTS”).
A typical cellular to WLAN, e.g., Wi-Fi, vertical handoff is now discussed with reference to
The contextual information server 48 of network 100 provides contextual elements 50, to the HDF 42 for processing and analysis to determine when a handoff should occur from one communication domain to another communication domain. The contextual elements 50 are contextual information relating to the mobile device and its operating environment; which are gathered from a variety of sources as described below. The contextual elements 50 include but are not limited to: received signal strength indication (“RSSI”), mobile device location, communication link quality, AP load, user mobile device preference, mobile device characteristics, application type, mobile device velocity, mobile device direction, and AP/cell site ID.
The contextual element of RSSI may be provided by, but is not limited to, the mobile device 30 or the radio access router 38. The contextual element of mobile device location may be provided via, but is not limited to, a global positioning satellite (“GPS”), a cellular assisted GPS, a WiFi-based location system, a proximity sensor, AP association, a cell site association, e.g., home location register (“HLR”) or HSS 52, and an ultra-wideband location system. The communication link quality and/or QoS may be provided by, but is not limited to, an AP reporting traffic load, an AP reporting packet error rate, network monitoring of packet loss, a router reporting packet loss or queue fill rate, and a signal-to-noise ratio (“SNR”) on an air interface.
The user mobile device preference may be provided by, but is not limited to, input via a system interface, input via the user mobile device, and via a user profile in the HSS 52. The user mobile device characteristics, e.g., support of 802.11e QoS mechanisms, support of 802.1×authentication (security feature), and support of power-save protocol (such as legacy mode or WiFi multimedia power-save) may be provided by, but are not limited to, the user mobile device 30 and the HSS 52.
The application type, e.g., video, voice or data, may be provided by, but is not limited to, an application client and application servers. Information about the type of applications used by the user mobile device 30 can be used in a VHO decision by adjusting other HO parameters according to whether the user is running real-time applications, e.g., voice, video, or not. For example, when the decision to make a VHO to the WLAN results from the comparison of the WLAN RSSI with thresholds, the user may select different pre-configured thresholds depending on whether he is having a real-time conversation (voice/video) or not, at the time the decision has to be made. A higher threshold may be selected if the user mobile device is having a real-time conversation as opposed to when user mobile device is only sending and receiving best-effort and background traffic.
The velocity of the user mobile device 30 may be derived from the location of the user mobile device 30 when there are at least two readings of location information obtained at different instants in time. The direction of the user mobile device 30 may be derived from the location, when there are at least two readings of location information obtained at different instants in time.
The AP/cell site ID may be provided by but is not limited to, the AP, the cell site and the mobile device 30. Information about the ID of a cell site or WLAN AP may be used in a VHO decision, for example when the ID is a clear indication of the administrative domains of the candidate networks (cellular and WLAN), and the user is restricted to roaming networks either being in the same administrative domain or having a roaming agreement with its administrative domain. For example, a user may wish to make VHOs to secure WLANs within its enterprise network, but not to other WLANs in the same enterprise, which do not offer the same level of security. A second category of WLANs may be provided for visitors on the campus. The two categories of WLANs may be part of two different administrative domains and identified by different ranges of basic service set identifiers (“BSSID”) and service set identifiers (“SSID”).
Any of the above contextual elements 50 may be described as the handoff decision parameters that are available to the HDF module 42 for evaluation. Accordingly, any one or more of the handoff decision parameters, i.e., modified or unmodified contextual elements 50 are evaluated by the HDF module 42 to make a handoff determination that is communicated to the user mobile device 30. All the modified or unmodified contextual elements 50 correspond to the user mobile device 30 and/or the various networks or subnetworks that serve as the operating environment for the user mobile device 30.
The HDF 42 includes a decision block 44 and a statistical and self-learning module 46, which can include storage for storing handoff (“HO”) statistics obtained from the network 100 and mobile device 30. The HO statistics may include information regarding the actual handoffs that occur on the interworking heterogeneous wireless access network 100 and may be stored in tables or registers within the statistical and self-learning module 46. For example, the HO statistics may be obtained from a set of counters that measure the handoffs that occur on the network 100. The HDF 42 may utilize any of the contextual elements 50 to make handoff decisions and notify a user mobile device 30 when to execute a handoff.
The statistical and self-learning process module 46 may also include self learning processes, which are executed in the network-based HDF decision block 44, to obtain handoff statistics from the network 100 and mobile device 30. Control targets or handoff parameters may be set administratively by the network operator, e.g., the carrier or the enterprise. For example, the handoff control parameters may vary depending on which part of the network the user 30 is located based on the number of access points or base transceiver terminals; or based on the traffic load. In one embodiment, the target handoff rates associated with different classes of customers are obtained. The actual handoff rates over different regions of the network are measured and the handoff decision parameters are dynamically adjusted to best match the target handoff rates over the entire network. If the handoff rates are too great, then an increase in the difference between a high threshold (“HI TRSH”) value and a low threshold (“LO TRSH”) value using a hysteresis-like handoff decision function will decrease or slow down the actual handoff rate.
The decision block 44 may include a dwell timer (not shown) that provides a latency factor or delay for use by the HDF 42 in its handoff decision-making process. The dwell timer may provide a typical latency factor in the range of 10 msec to 100 msec, but the range may be on the order of seconds in certain circumstances. The dwell timer is an example of a handoff decision parameter.
The operation of an embodiment of the handoff decision function 42 of network 100 is discussed with respect to the flowchart of
The operation of another embodiment of the handoff decision function 42 of the network 100 is discussed with respect to the flowchart of
If the second network signal strength falls below the HI TRSH, the service in the first network is retained and no handoff will occur (step S218). Otherwise, determine if the dwell timer has expired (step S220) and if not, then the first network is retained and no handoff will occur and the second network signal strength is monitored to determine if it has fallen below the HI TRSH (step S216). If the dwell timer has expired, then the system will notify the user device 30 to handoff the call session to the second network from the first network (step S222).
The operation of an embodiment of the handoff decision function 42 of the network 100 is discussed with respect to the flowchart of
If the first network signal strength returns above the LO TRSH, the service in the first network is retained and no handoff will occur (step S318). Otherwise, determine if the dwell timer has expired (step S320) and if not, then the first network is retained and no handoff will occur and the first network signal strength is monitored to determine if it has returned above the LO TRSH (step S316). If the dwell timer has expired, then the system will notify the user device 30 to handoff the call session to the second network from the first network (step S322).
The present invention advantageously provides a method, system and apparatus for facilitating handoff of a mobile user device across inter-technology networks by employing a handoff decision function module that processes various contextual network wide status inputs and data, including user device network preferences. By employing this improved handoff scheme, the mobile end user will experience a seamless transition from one technology domain to another technology domain without interruption of a call session.
The present invention can be realized in hardware, software, or a combination of hardware and software. An implementation of the method and system of the present invention can be realized in a centralized fashion in one computing system or in a distributed fashion where different elements are spread across several interconnected computing systems. Any kind of computing system, or other apparatus adapted for carrying out the methods described herein, is suited to perform the functions described herein.
A typical combination of hardware and software could be a specialized or general-purpose computer system having one or more processing elements and a computer program stored on a storage medium that, when loaded and executed, controls the computer system such that it carries out the methods described herein. The present invention can also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which, when loaded in a computing system is able to carry out these methods. Storage medium refers to any volatile or non-volatile storage device.
Computer program or application in the present context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following a) conversion to another language, code or notation; b) reproduction in a different material form. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. Significantly, this invention can be embodied in other specific forms without departing from the spirit or essential attributes thereof, and accordingly, reference should be had to the following claims, rather than to the foregoing specification, as indicating the scope of the invention.
It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described herein above. A variety of modifications and variations are possible in light of the above teachings without departing from the spirit or essential attributes thereof, and accordingly, reference should be had to the following claims, rather than to the foregoing specification, as indicating the scope of the of the invention.
It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope and spirit of the invention, which is limited only by the following claims.
