WO2019090788A1

WO2019090788A1 - Method and apparatus for triggering network handover, and computer storage medium

Info

Publication number: WO2019090788A1
Application number: PCT/CN2017/110752
Authority: WO
Inventors: 唐海
Original assignee: Oppo广东移动通信有限公司
Priority date: 2017-11-13
Filing date: 2017-11-13
Publication date: 2019-05-16

Abstract

Disclosed in the present invention are a method and apparatus for triggering a network handover, and a computer storage medium. The method comprises: when a first core network element determines that a handover condition is satisfied, sending a handover request message to a base station, the handover request message being used for triggering a network handover process of a terminal executed by the base station.

Description

Method and device for triggering network switching, computer storage medium

Technical field

The present invention relates to the field of mobile communications technologies, and in particular, to a method and apparatus for triggering network switching, and a computer storage medium.

Background technique

The fifth generation of mobile communication (5G) networks tend to be diversified, broadband, integrated, and intelligent. In the early days of 5G network development, it needs to be compatible with the fourth generation mobile communication (4G) network, so that the intelligent terminal can select the appropriate network to access the Internet according to the needs.

However, in some scenarios, it is necessary to implement switching between networks. For example, after the terminal uses the upper limit of traffic on the 5G network, there is a need to switch from the 5G network to the 4G network. Currently, when a terminal needs to implement handover between networks due to an event, the terminal often still resides on the current network. To do this, the network needs to be triggered by a certain policy. For example, the network side adjusts the Radio Access Technology Frequency Selection Policy (RFSP) to control the terminal to perform network switching at a certain time after the event occurs. . However, this switching mode will cause the terminal to continue to use the network to access the Internet after the event occurs (for example, after the traffic reaches the upper limit), resulting in additional network overhead and no precise control of the terminal traffic.

Summary of the invention

To solve the above technical problem, an embodiment of the present invention provides a method and apparatus for triggering network switching, and a computer storage medium.

The method for triggering network switching provided by the embodiment of the present invention includes:

When the first core network element determines that the handover condition is met, the handover request message is sent to the base station, The handover request message is used to trigger the base station to perform a network handover procedure of the terminal.

In the embodiment of the present invention, when the first core network element determines that the handover condition is met, the handover request message is sent to the base station, including:

When the first core network element determines that the used traffic of the terminal on the first network exceeds a preset threshold, the first core network element sends a handover request message to the base station.

In the embodiment of the present invention, the first core network element determines that the used traffic of the terminal on the first network exceeds a preset threshold, and includes:

The first core network element receives the first trigger message sent by the second core network element, where the first trigger message is used to indicate that the used traffic of the terminal on the first network exceeds a preset threshold.

The first core network element determines whether the terminal moves into the target area or moves away from the target area, and sends a handover request message to the base station.

When receiving the second trigger message, the first core network element sends a handover request message to the base station.

In the embodiment of the present invention, the first core network element receives the second trigger message, including:

The first core network element receives the handover request message sent by the third core network element.

In the embodiment of the present invention, the handover request message is used to trigger the base station to perform a network handover process of the terminal, which is:

The handover request message is used to instruct the base station to perform a handover procedure in which the terminal is handed over from the first network to the second network.

In the embodiment of the present invention, the handover request message carries a network handover type, and the network handover type includes: an access type handover, or an access system handover.

The device for triggering network switching provided by the embodiment of the present invention includes:

a determining unit configured to determine whether a switching condition is met;

The sending unit is configured to send a handover request message to the base station when the handover condition is met, where the handover request message is used to trigger the base station to perform a network handover procedure of the terminal.

In the embodiment of the present invention, the determining unit includes: a first determining sub-unit, configured to determine whether the usage flow of the terminal on the first network exceeds a preset threshold;

The sending unit is configured to: when it is determined that the used traffic of the terminal on the first network exceeds a preset threshold, send a handover request message to the base station.

In the embodiment of the present invention, the device further includes: a receiving unit, configured to receive a first trigger message sent by the second core network element, where the first trigger message is used to indicate the use of the terminal on the first network The traffic exceeds a preset threshold;

The first determining sub-unit is configured to: determine, according to the first trigger message, whether the usage flow of the terminal on the first network exceeds a preset threshold.

In the embodiment of the present invention, the determining unit includes: a second determining subunit, configured to determine whether the terminal moves into the target area or moves away from the target area;

The sending unit is specifically configured to: when it is determined that the terminal moves into the target area or moves away from the target area, sends a handover request message to the base station.

In the embodiment of the present invention, the determining unit includes: a third determining subunit, configured to determine whether a second trigger message is received;

The sending unit is specifically configured to: when receiving the second trigger message, send a handover request message to the base station.

In the embodiment of the present invention, the third determining sub-unit is specifically configured to: determine whether a handover request message sent by the third core network element is received.

The computer storage medium provided by the embodiment of the present invention has stored thereon computer executable instructions, and the computer executable instructions are implemented by the processor to implement the above method for triggering network switching.

In the technical solution of the embodiment of the present invention, when the first core network element determines that the handover condition is met, the first core network element sends a handover request message to the base station, where the handover request message is used to trigger the base station to perform a network handover process of the terminal. According to the technical solution of the embodiment of the present invention, the first core network element, for example, a policy control function (PCF) network element or a policy and charging rule function (PCRF) network element can When it is determined that the handover condition is met, the base station is triggered to perform the network handover process of the terminal, thereby avoiding additional network overhead caused by the terminal continuing to access the Internet on the original network, and at the same time, accurately controlling the traffic of the terminal.

DRAWINGS

The drawings described herein are intended to provide a further understanding of the invention, and are intended to be a part of the invention. In the drawing:

1 is a system architecture diagram of a 5G network according to an embodiment of the present invention;

2 is a system architecture diagram of a 4G network according to an embodiment of the present invention;

3 is a schematic flowchart 1 of a method for triggering network switching according to an embodiment of the present invention;

4 is a second schematic flowchart of a method for triggering network switching according to an embodiment of the present invention;

FIG. 5 is a schematic flowchart 3 of a method for triggering network switching according to an embodiment of the present invention;

FIG. 6 is a schematic flowchart 4 of a method for triggering network switching according to an embodiment of the present invention;

FIG. 7 is a schematic flowchart 5 of a method for triggering network switching according to an embodiment of the present invention;

FIG. 8 is a schematic flowchart 6 of a method for triggering network switching according to an embodiment of the present invention;

FIG. 9 is a schematic flowchart diagram 7 of a method for triggering network switching according to an embodiment of the present invention;

10 is a schematic flowchart 8 of a method for triggering network switching according to an embodiment of the present invention;

11 is a schematic flowchart nin of a method for triggering network switching according to an embodiment of the present invention;

FIG. 12 is a first schematic structural diagram of a device for triggering network switching according to an embodiment of the present invention; FIG.

FIG. 13 is a second schematic structural diagram of a device for triggering network switching according to an embodiment of the present invention;

FIG. 14 is a schematic structural diagram of a terminal according to an embodiment of the present invention.

Detailed ways

The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

FIG. 1 is a system architecture diagram of a 5G network according to an embodiment of the present invention. As shown in FIG. 1 , the devices involved in the 5G network system include:

Terminal (UE, User Equipment), Radio Access Network (RAN), User Plane Function (UPF), Data Network (DN, Data Network), Receive Core Access, and Mobility Manager (AMF) , Core Access and Mobility Management Function), Session Management Function (SMF), Policy Control Function (PCF, Policy Control Function), Application Function (AF), Authentication Server Function (AUSF, Authentication Server Function) ), Unified Data Management (UDM).

2 is a system architecture diagram of a 4G network according to an embodiment of the present invention. As shown in FIG. 2, the devices involved in the 4G network system include:

Terminal (UE, User Equipment), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), Mobility Management Entity (MME) network element, Serving GPRS Support Node (SGSN, Serving) GPRS Support Node), Home Subscriber Server (HSS), Serving Gateway, Packet Data Network Gateway (PDN), Policy and Charging Rules Function Unit (PCRF, Policy and Charging) Rules Function).

The foregoing examples of FIG. 1 and FIG. 2 are only examples of a network architecture that implements the embodiments of the present invention. The embodiments of the present invention are not limited to the network structures described in FIG. 1 and FIG.

FIG. 3 is a schematic flowchart 1 of a method for triggering network handover according to an embodiment of the present invention. As shown in FIG. 3, the method for triggering network handover includes the following steps:

Step 301: The first core network element determines that the handover condition is met, and sends a handover request message to the base station, where the handover request message is used to trigger the base station to perform a network handover procedure of the terminal.

Here, the determining, by the first core network element, that the handover condition is satisfied may be implemented by, but not limited to, the following manner:

1) The first core network element determines that the usage flow of the terminal on the first network exceeds a preset threshold, and sends a handover request message to the base station.

Specifically, the first core network element receives the first trigger message sent by the second core network element, where the first trigger message is used to indicate that the used traffic of the terminal on the first network exceeds a preset threshold.

2) The first core network element determines that the terminal moves into the target area or moves away from the target area, and sends a handover request message to the base station.

3) The first core network element sends a handover request message to the base station when receiving the second trigger message.

Specifically, the first core network element receives the handover request message sent by the third core network element.

In the above solution, the handover request message is used to instruct the base station to perform a handover procedure in which the terminal is handed over from the first network to the second network.

In the above solution, the handover request message carries a network handover type, and the network handover type includes: an access type handover, or an access system handover.

Various embodiments of the present invention are presented below based on a 5G network architecture.

FIG. 4 is a schematic flowchart 2 of a method for triggering network handover according to an embodiment of the present invention. As shown in FIG. 4, the method for triggering network handover includes the following steps:

Step 401: The PCF network element determines whether the usage traffic of the terminal on the 5G network exceeds a preset threshold.

In an embodiment, the PCF network element receives a first trigger message sent by the AMF network element/SMF network element, where the first trigger message is used to indicate that the used traffic of the terminal on the 5G network exceeds a preset threshold.

Step 402: The PCF network element determines that the usage flow of the terminal on the 5G network exceeds a preset threshold, and sends a handover request message to the gNB.

In the embodiment of the present invention, the handover request message is used to indicate that the gNB performs a handover procedure in which the terminal is switched from the 5G network to the 4G network.

In an embodiment, the handover request message carries a network handover type, such as a RAT handover or an EPS handover.

FIG. 5 is a schematic flowchart 3 of a method for triggering network switching according to an embodiment of the present invention. As shown in FIG. 5, the method for triggering network switching includes the following steps:

Step 501: The PCF network element determines whether the terminal moves into the target area or moves away from the target area.

Step 502: The PCF network element determines that the terminal moves into the target area or moves away from the target area, and sends a handover request message to the gNB.

In an embodiment, the handover request message carries a network handover type, such as a RAT switch. Change or EPS switch.

FIG. 6 is a schematic flowchart diagram of a method for triggering network handover according to an embodiment of the present invention. As shown in FIG. 6 , the method for triggering network handover includes the following steps:

Step 601: The PCF network element determines whether a second trigger message is received.

In an embodiment, if the PCF network element receives the handover request message sent by the AF network element, it determines that the second trigger message is received.

Here, the handover request message sent by the AF network element may also carry a network handover type, such as RAT handover or EPS handover.

Step 602: When receiving the second trigger message, the PCF network element sends a handover request message to the gNB.

FIG. 7 is a schematic flowchart of a method for triggering network handover according to an embodiment of the present invention. As shown in FIG. 7, the method for triggering network handover includes the following steps:

Step 701: The AF network element sends a HO request message to the PCF network element.

Here, the HO request message carries a network handover type, such as RAT handover, or EPS handover.

Step 702: The AMF/SMF network element sends a trigger message to the PCF network element, where the trigger message is used to indicate that the usage traffic of the terminal on the 5G network exceeds a preset threshold.

In the above solution, the order of execution of steps 701 and 702 is not limited.

Step 703: The PCF network element sends a HO request message to the gNB.

Step 704: The UE performs a HO procedure with each network element on the network side.

With the technical solution of the embodiment of the present invention, the PCF immediately triggers the UE to return to the 4G network if it knows that the usage flow of the UE in the 5G network reaches the upper limit.

Various embodiments of the present invention are presented below based on a 4G network architecture.

FIG. 8 is a schematic flowchart diagram of a method for triggering network handover according to an embodiment of the present invention. As shown in FIG. 8 , the method for triggering network handover includes the following steps:

Step 801: The PCRF network element determines whether the usage traffic of the terminal on the 4G network exceeds a preset threshold.

In an embodiment, the PCF network element receives a first trigger message sent by the MME network element/PDN-GW network element, where the first trigger message is used to indicate that the used traffic of the terminal on the 4G network exceeds a preset. Threshold.

Step 802: The PCRF network element determines that the usage flow of the terminal on the 4G network exceeds a preset threshold, and sends a handover request message to the eNB.

In the embodiment of the present invention, the handover request message is used to indicate that the eNB performs a handover process in which the terminal is switched from the 4G network to the 3G network.

FIG. 9 is a schematic flowchart diagram of a method for triggering network handover according to an embodiment of the present invention. As shown in FIG. 9, the method for triggering network handover includes the following steps:

Step 901: The PCRF network element determines whether the terminal moves into the target area or moves away from the target area.

Step 902: The PCRF network element determines that the terminal moves into the target area or moves away from the target area, and sends a handover request message to the eNB.

FIG. 10 is a schematic flowchart diagram of a method for triggering network handover according to an embodiment of the present invention. As shown in FIG. 10, the method for triggering network handover includes the following steps:

Step 1001: The PCRF network element determines whether a second trigger message is received.

In an embodiment, if the PCRF network element receives the handover request message sent by the AF network element, it determines that the second trigger message is received.

Step 1002: The PCRF network element sends a handover request message to the eNB when receiving the second trigger message.

FIG. 11 is a schematic flowchart diagram of a method for triggering network switching according to an embodiment of the present invention. As shown in FIG. 11, the method for triggering network switching includes the following steps:

Step 1101: The AF network element sends an HO request message to the PCRF network element.

Step 1102: The MME/PDN-GW network element sends a trigger message to the PCRF network element, where the trigger message is used to indicate that the usage traffic of the terminal on the 4G network exceeds a preset threshold.

In the above solution, the order of execution of step 1101 and step 1102 is not limited.

Step 1103: The PCRF network element sends an HO request message to the eNB.

Step 1104: The UE performs a HO procedure with each network element on the network side.

The technical solution of the embodiment of the present invention enables the PCRF to immediately trigger the UE to return to the 3G network if it knows that the usage traffic of the UE in the 4G network reaches the upper limit.

In the above solution, only the terminal is switched from the 5G network to the 4G network, or the 4G network is switched to the 3G network. In actual applications, the network switching is not limited thereto, and any implementation based on the technical solution of the embodiment of the present invention is implemented. The network switching is all within the scope of protection of the embodiments of the present invention.

FIG. 12 is a first schematic structural diagram of a device for triggering network switching according to an embodiment of the present invention. As shown in FIG. 12, the device includes:

The determining unit 1201 is configured to determine whether the switching condition is met;

The sending unit 1202 is configured to send a handover request to the base station when the handover condition is met. The message, the handover request message is used to trigger the base station to perform a network handover procedure of the terminal.

It should be understood by those skilled in the art that the implementation functions of the units in the apparatus for triggering network switching shown in FIG. 12 can be understood by referring to the related description of the foregoing method for triggering network switching. The functions of each unit in the apparatus for triggering network switching shown in FIG. 12 can be implemented by a program running on a processor, or can be realized by a specific logic circuit.

FIG. 13 is a second structural diagram of a device for triggering network switching according to an embodiment of the present invention. As shown in FIG. 13, the device includes:

The determining unit 1301 is configured to determine whether the switching condition is met;

The sending unit 1302 is configured to send a handover request message to the base station when the handover condition is met, where the handover request message is used to trigger the base station to perform a network handover procedure of the terminal.

In an embodiment, the determining unit 1301 includes: a first determining sub-unit 13011, configured to determine whether the usage flow of the terminal on the first network exceeds a preset threshold;

The sending unit 1302 is specifically configured to: when it is determined that the used traffic of the terminal on the first network exceeds a preset threshold, send a handover request message to the base station.

In the above solution, the device further includes: a receiving unit 1303, configured to receive a first trigger message sent by the second core network element, where the first trigger message is used to indicate usage flow of the terminal on the first network. Exceeding a preset threshold;

The first determining sub-unit 13011 is configured to: determine, according to the first trigger message, whether the usage flow of the terminal on the first network exceeds a preset threshold.

In an embodiment, the determining unit 1301 includes: a second determining subunit 13012, configured to determine whether the terminal moves into the target area or moves away from the target area;

The sending unit 1302 is specifically configured to: when it is determined that the terminal moves into the target area or moves away from the target area, sends a handover request message to the base station.

In an embodiment, the determining unit 1301 includes: a third determining subunit 13013, configured to determine whether a second trigger message is received;

The sending unit 1302 is specifically configured to: when receiving the second trigger message, send a handover request message to the base station.

In the above solution, the third determining sub-unit 13013 is specifically configured to: determine whether a handover request message sent by the third core network element is received.

In the embodiment of the present invention, the handover request message is used to trigger the network handover process performed by the base station, which means:

It should be understood by those skilled in the art that the implementation functions of the units in the apparatus for triggering network switching shown in FIG. 13 can be understood by referring to the related description of the foregoing method for triggering network switching. The functions of the units in the apparatus for triggering network switching shown in FIG. 13 can be implemented by a program running on a processor, or can be realized by a specific logic circuit.

In the embodiment of the present invention, the device for triggering network switching may be stored in a computer storage medium if it is implemented in the form of a software function module and sold or used as an independent product. Based on such understanding, the technical solution of the embodiments of the present invention may be embodied in the form of a software product in essence or in the form of a software product stored in a storage medium, including a plurality of instructions. A computer device (which may be a personal computer, server, or network device, etc.) is caused to perform all or part of the methods described in various embodiments of the present invention. The foregoing storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read only memory (ROM), a magnetic disk, or an optical disk. Thus, embodiments of the invention are not limited to any specific combination of hardware and software.

Correspondingly, an embodiment of the present invention further provides a computer storage medium, where computer executable instructions are stored, and when the computer executable instructions are executed by a processor, the embodiment of the present invention is implemented. The above method for triggering network switching.

14 is a schematic structural diagram of a terminal according to an embodiment of the present invention. As shown in FIG. 14, the terminal 140 may include one or more (only one shown) processor 1402 (the processor 1402 may include but is not limited to micro processing). A processing device such as a Micro Controller Unit (MCU) or a Programmable Gate Array (FPGA), a memory 1404 for storing data, and a transmission device 1406 for communication functions. It will be understood by those skilled in the art that the structure shown in FIG. 14 is merely illustrative and does not limit the structure of the above electronic device. For example, terminal 140 may also include more or fewer components than shown in FIG. 14, or have a different configuration than that shown in FIG.

The memory 1404 can be used to store software programs and modules of the application software, such as program instructions/modules corresponding to the method for triggering network switching in the embodiment of the present invention, and the processor 1402 executes by executing the software programs and modules stored in the memory 1404. Various functional applications and data processing, that is, the above methods are implemented. Memory 1404 can include high speed random access memory and can also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid state memory. In some examples, memory 1404 can further include memory remotely located relative to processor 1402, which can be connected to terminal 140 over a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

Transmission device 1406 is for receiving or transmitting data via a network. The network specific examples described above may include a wireless network provided by a communication provider of the terminal 140. In one example, the transmission device 1406 includes a Network Interface Controller (NIC) that can be connected to other network devices through a base station to communicate with the Internet. In one example, the transmission device 1406 can be a radio frequency (RF) module for communicating with the Internet wirelessly.

The technical solutions described in the embodiments of the present invention may be arbitrarily arranged without conflict. combination.

In the several embodiments provided by the present invention, it should be understood that the disclosed method and smart device may be implemented in other manners. The device embodiments described above are merely illustrative. For example, the division of the unit is only a logical function division. In actual implementation, there may be another division manner, such as: multiple units or components may be combined, or Can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, or direct coupling, or communication connection of the components shown or discussed may be indirect coupling or communication connection through some interfaces, devices or units, and may be electrical, mechanical or other forms. of.

The units described above as separate components may or may not be physically separated, and the components displayed as the unit may or may not be physical units, that is, may be located in one place or distributed to multiple network units; Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one second processing unit, or each unit may be separately used as one unit, or two or more units may be integrated into one unit; The above integrated unit can be implemented in the form of hardware or in the form of hardware plus software functional units.

The above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention.

Claims

A method of triggering network switching, the method comprising:

When the first core network element determines that the handover condition is met, the handover request message is sent to the base station, where the handover request message is used to trigger the base station to perform a network handover procedure of the terminal.
The method for triggering network handover according to claim 1, wherein, when the first core network element determines that the handover condition is met, the handover request message is sent to the base station, including:

When the first core network element determines that the used traffic of the terminal on the first network exceeds a preset threshold, the first core network element sends a handover request message to the base station.
The method for triggering network switching according to claim 2, wherein the first core network element determines that the usage traffic of the terminal on the first network exceeds a preset threshold, including:

The first core network element receives the first trigger message sent by the second core network element, where the first trigger message is used to indicate that the used traffic of the terminal on the first network exceeds a preset threshold.
The method for triggering network handover according to claim 1, wherein, when the first core network element determines that the handover condition is met, the handover request message is sent to the base station, including:

The first core network element determines whether the terminal moves into the target area or moves away from the target area, and sends a handover request message to the base station.
The method for triggering network handover according to claim 1, wherein, when the first core network element determines that the handover condition is met, the handover request message is sent to the base station, including:

When receiving the second trigger message, the first core network element sends a handover request message to the base station.
The method for triggering network switching according to claim 5, wherein the first core network element receives the second trigger message, including:

The first core network element receives the handover request message sent by the third core network element.
The method for triggering network switching according to any one of claims 1 to 6, wherein The handover request message is used to trigger the base station to perform a network handover process of the terminal, which is:

The handover request message is used to instruct the base station to perform a handover procedure in which the terminal is handed over from the first network to the second network.
The method for triggering network handover according to claim 7, wherein the handover request message carries a network handover type, and the network handover type comprises: an access type handover, or an access system handover.
A device for triggering network switching, the device comprising:

a determining unit configured to determine whether a switching condition is met;

The sending unit is configured to send a handover request message to the base station when the handover condition is met, where the handover request message is used to trigger the base station to perform a network handover procedure of the terminal.
The device for triggering network switching according to claim 9, wherein the determining unit comprises: a first determining subunit, configured to determine whether the usage flow of the terminal on the first network exceeds a preset threshold;

The sending unit is configured to: when it is determined that the used traffic of the terminal on the first network exceeds a preset threshold, send a handover request message to the base station.
The device for triggering network switching according to claim 10, wherein the device further comprises: a receiving unit, configured to receive a first trigger message sent by the second core network element, where the first trigger message is used to indicate The usage traffic of the terminal on the first network exceeds a preset threshold;

The first determining sub-unit is configured to: determine, according to the first trigger message, whether the usage flow of the terminal on the first network exceeds a preset threshold.
The apparatus for triggering network switching according to claim 9, wherein the determining unit comprises: a second determining subunit configured to determine whether the terminal moves into a target area or moves away from the target area;

The sending unit is specifically configured to: when it is determined that the terminal moves into the target area Or, when moving away from the target area, sending a handover request message to the base station.
The apparatus for triggering network switching according to claim 9, wherein the determining unit comprises: a third determining subunit configured to determine whether a second trigger message is received;

The sending unit is specifically configured to: when receiving the second trigger message, send a handover request message to the base station.
The device for triggering network switching according to claim 13, wherein the third determining subunit is specifically configured to: determine whether a handover request message sent by the third core network element is received.
The device for triggering network switching according to any one of claims 9 to 14, wherein the handover request message is used to trigger the base station to perform a network handover process of the terminal, which means:

The handover request message is used to instruct the base station to perform a handover procedure in which the terminal is handed over from the first network to the second network.
The apparatus for triggering network switching according to claim 15, wherein the handover request message carries a network handover type, and the network handover type comprises: an access type handover, or an access system handover.
A computer storage medium having stored thereon computer executable instructions for performing the method steps of any of claims 1-8 when executed by a processor.