WO2008131581A1

WO2008131581A1 - System and method for updating uati of an access terminal

Info

Publication number: WO2008131581A1
Application number: PCT/CN2007/001391
Authority: WO
Inventors: Sha Lv; Shunlin Chen; Youli Song
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2007-04-26
Filing date: 2007-04-26
Publication date: 2008-11-06
Anticipated expiration: 2009-10-26
Also published as: CN101467399A; CN101467399B

Abstract

A system for communication of an access terminal in a wireless network having a plurality of subnets. The system determines, based upon movement of the access terminal in a dormant state between subnets, and upon ColorCode and SecondaryColorCode values of each subnet, whether or not the access terminal should immediately initiate a Unicast Access Terminal Identifier (UATI) update request, or delay the Unicast Access Terminal Identifier (UATI) update.

Description

SYSTEM AND METHOD FOR UPDATING UATI OF AN

ACCESS TERMINAL

Field of the Technology

The present invention relates generally to wireless communications, and more particularly, to a versatile system and method for updating Unicast Access Terminal Identifier (UATI) for an Access Terminal in a dormant state.

Background of the Invention

Under the High Rate Packet Data (HRPD) standard defined by the 3rd Generation Partner Project 2 (3GPP2), when an Access Terminal (AT) moves from one subnet into another subnet in a dormant state, the AT is required to initiate a Unicast Access Terminal Identifier (UATI) request - updating the UATI of the AT and routing-related information of its corresponding user. To reduce UATI requests resulting from frequent moves between subnets of the AT in a dormant state, the HRPD 3.0 protocol in 3GPP2 provides a function of SecondaryColorCode. When a dormant AT moves from a source subnet to a target subnet, if ColorCode stored by the AT matches the SecondaryColorCode of the target subnet, then the AT does not initiate a UATI request. The AT in the target subnet is in an idle state.

Therefore, as a dormant AT moves into a target subnet, if the AT does not establish a connection with the target subnet after comparing the stored ColorCode in the AT with SecondaryColorCode of the target subnet, then neither the source subnet nor the target subnet may directly know the AT's location.

Under the current HRPD standard, if a dormant AT does not establish connection with a target subnet, the AT may be connected with the target subnet through communications between subnets, and a source subnet may call the AT by paging across subnets.

FIG. 1 illustrates a diagram of signaling between HRPD subnets. AT 100 establishes a session in a source subnet 102, and saves the session information. In a SectorParameters message of Source Subnet 102, ColorCode is 7. Target Subnet 104 has a SecondaryColorCode of 7. Therefore, when AT 100 moves to Target Subnet 104 in a dormant state, AT 100 does not initiate a UATI request, because the ColorCode stored by AT 100 matches the SecondaryColorCode of Target Subnet 104.

When Source Subnet 102 needs to page AT 100, paging will first be done within Source Subnet 102. If paging within Source Subnet 102 fails, Source Subnet 102 will find AT 100 in Target Subnet 104 through communications between Source Subnet 102 and Target Subnet 104.

Since Target Subnet 104 does not have session information of AT 100, if AT 100 needs to establish a connection with Target Subnet 104, Target Subnet 104 may obtain session information of AT 100 in Source Subnet 102 through subnet communications, and establish the connection.

Thus, by utilizing the SecondaryColorCode feature, an AT moving around in a dormant state from one subnet to another subnet may not update UATI, and signaling between an Access Network (AN) and the AT may be transmitted through subnet communications.

When a call from a source subnet needs to be connected to an AT, since the AT has moved to a target subnet, paging the AT within the source subnet will not succeed. Then, paging may be made between the source subnet and the target subnet to get to the AT. An unsuccessful paging within the source subnet, and paging across the subnets obviously bring forth greater paging delay, or even missing pages, resulting in poor call connection performance.

When the AT in the target subnet initiates a call request, the target subnet will have to retrieve session information associated with the AT from the source subnet, since the target subnet does not have such information. After the session information is transferred to the target subnet, the call set-up may proceed, and A8, AlO and UATI information is updated. This delays call set-up for the AT, and results in poor call connection performance.

Therefore, there is the need for an effective method of signaling when an AT moves around within two or more subnets, particularly while in a dormant state. Summary of the Invention

A system for communication of an access terminal, in a wireless network having a plurality of subnets, is provided. The system determines, based upon movement of the access terminal in a dormant state between subnets, and upon ColorCode and SecondaryColorCode values of each subnet, whether or not the access terminal should immediately initiate a Unicast Access Terminal Identifier (UATI) update request, or delay the Unicast Access Terminal Identifier (UATI) update.

The following description and drawings set forth in detail a number of illustrative embodiments of the invention. These embodiments are indicative of but a few of the various ways in which the present invention may be utilized.

Brief Description of the Drawings

For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:

FIG. 1 is a diagram illustrating a PRIOR ART communication system;

FIG. 2 is a flow diagram illustrating one embodiment of the present invention;

FIG. 3 is a flow diagram illustrating yet another embodiment of the present invention; and

FIG. 4 is a flow diagram illustrating yet another embodiment of the present invention.

Detailed Description of the Invention

The following discussion is presented to enable a person skilled in the art to make and use the invention. The general principles described herein may be applied to embodiments and applications other than those detailed below without departing from the spirit and scope of the present invention as defined herein. The present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

The embodiments of the present invention are described now in reference to FIGS. 2-4, and in comparison and reference to certain aspects of the PRIOR ART system of FIG. 1.

When an Access Terminal (AT) 100, in a dormant state, moves to a Target Subnet 104 from a Source Subnet 102 - and if AT 100 determines, that ColorCode of AT 100 already stored matches the SecondaryColorCode of Target Subnet 104, i.e., no Unicast Access Terminal Identifier (UATI) update is required in Target Subnet 104 - AT 100 may delay the UATI update in Target Subnet 104, instead of not initiating the UATI update.

There may be various ways to delay the UATI update. One embodiment for AT 100 to delay UATI update may be that AT 100 may initiate a UATI update timer. An UATI update request may then be initiated by AT 100 in Target Subnet 104 if the UATI update timer expires. The length of the UATI update timer may be defined in various ways, without departing the scope and spirit of the present invention. For example, the value of the UATI update timer may be defined by target subnet 104 which the AT moves in, and sent to AT 100. One embodiment may define the length of the UATI update timer by a value of UATIUpdateTriggerTimer in a SectorParameters message sent by Target Subnet 104. Table 1, below, shows UATIUpdateTriggerTimer in a related part of a SectorParameters message. The UATIUpdateTriggerTimer is underlined.

Table 1

Zero or SecondaryColorCodeCount occurrences of the following field:

SecondaryColorCode

If SecondaryColorCodelncluded equals "0", the AN will not define a value for the UATIUpdateTriggerTimer field. However, if the SecondaryColorCodelncluded is not "0", the AN may define a value for the UATIUpdateTriggerTimer, with seconds as the unit.

The AN may set up the value for the UATIUpdateTriggerTimer in a SectorParameters message according to current network payload, and a default value may be 1800. The value of UATIUpdateTriggerTimer may be increased accordingly as network payload increases, and vice versa.

The AN may also send a value of time to AT 100. AT 100 may determine the length for the UATI update timer using the difference between the time received and it's current time. For example, AT 100 receives a value of time: 1 1 :05am, and the current time of AT 100 is 11 :02am, then the length of the UATI update timer is 180 seconds.

If, before the UATI update timer expires, AT 100 moves back to Source Subnet 102, the UATI update timer is stopped. However, if AT 100 moves to another subnet, and if no UATI update is required based on the SecondaryColorCode of the another subnet, then the UATI update timer is reset by the value of UATIUpdateTriggerTimer in a SectorParameters message of the new access subnet, and initiated.

After UATI update timer expires, AT 100 sends a UATI update request for updating UATI to Target Subnet 104. The target AN then re-assigns a UATI responsive to the UATI update request, and retrieves session information of AT 100 from Source Subnet 102. The AT session information will now be stored in Target Subnet 104, and Source Subnet 102 will not keep the session information any more. Once AT 100 gets connected in Target Subnet 104, or gets UATI updated, AT 100 stops the UATI update timer.

In reference to one embodiment depicted in FIG. 2, an AT 200 in a dormant state moves to an adjacent Target Subnet 204, and updates UATI in Target Subnet

204. Initially, AT 200, in the serving area of a Source Subnet 202, receives sector parameters sent by the Source Subnet 202 - including ColorCode with a value of 7, SecondaryColorCode with values of 8 and 9, and UATIUpdateTriggerTimer Tl .

AT 200 then requests a Packet Control Function (PCF) entity 206 to register for a session in Source Subnet 202, and is assigned a UATI. After successful registration, AT 200 stores the ColorCode for Source Subnet 202 with a value of 7, and transforms to a dormant packet data session state.

As AT 200 moves to Target Subnet 204 in a dormant state, it receives sector parameters sent by Target Subnet 204 - which include ColorCode with a value of 8, SecondaryColorCode with a value of 7, and UATIUpdateTriggerTimer with a value of T2. AT 200 determines that ColorCode stored in AT 200 has a value that is included in SecondaryColorCode of Target Subnet 204 (i.e., 7), and the ColorCode stored does not equal ColorCode of Target Subnet 204, then AT 200 initiates a UATI update timer with length T2.

When the UATI update timer expires, AT 200 stops the UATI update timer, and requests a UATI update in Target Subnet 204. Target Subnet 204 then reassigns a UATI to AT 200. AT 200 then re-stores the ColorCode with a value of 8, i.e. the value of ColorCode of Target Subnet 204, after a successful UATI update.

Another embodiment is illustrated now with reference to FIG. 3. AT 300 in a dormant state moves across a number of adjacent subnets, and updates UATI in a target subnet. First, AT 300, in the serving area of a Source Subnet 302, receives sector parameters sent by Source Subnet 302, including ColorCode with a value of 7, SecondaryColorCode with a value of 8, and UATIUpdateTriggerTimer Tl . AT 300 requests a PCF (308) to register for a session in Source Subnet 302, and is assigned a UATI. ColorCode is 7. After a successful registration, AT 300 stores the ColorCode for Source Subnet 302 with a value of 7, and transforms to a dormant packet data session state.

As AT 300 moves to a Target Subnet 1 304 in a dormant state, it receives sector parameters sent by Target Subnet 1 304, which include ColorCode with a value of 8, SecondaryColorCode with values of 7 and 9, and UATIUpdateTriggerTimer with a value of T2. AT 300 determines that ColorCode of AT 300 already stored has a value that is included in SecondaryColorCode of Target Subnet 1 304 (i.e., 7), and that Target Subnet 1 304 ColorCode is not 7. AT 300 then initiates a UATI update timer with length of T2.

Before the UATI update timer expires. AT 300 moves into a Target Subnet 2 306 in a dormant state. AT 300 receives sector parameters sent by Target Subnet 2 306, including ColorCode with a value of 9, SecondaryColorCode with values of 7 and 8, and UATIUpdateTriggerTimer with a value of T3. AT 300 determines that ColorCode of AT 300 already stored has a value that is included in SecondaryColorCode of Target Subnet 2 306, i.e., 7, and Target Subnet 2 306 ColorCode is not 7. Then, AT 300 resets the UATI update Timer to T3 and initiates the UATI update timer.

If the UATI update timer expires, AT 300 stops the UATI update timer, and requests a UATI update in Target Subnet 2 306. Target Subnet 2 306 re-assigns a UATI to AT 300. AT 300 then stores the ColorCode with a value of 9 after a successful UATI update.

Another embodiment is illustrated now in relation to FIG. 4. An AT 400 in a dormant state moves across to an adjacent Target Subnet 404 from a Source Subnet

402 for a short time period, and returns back to Source Subnet 402. However, AT

400 does not update UATI. The process begins when AT 400 in the serving area of

Source Subnet 402, receives sector parameters sent by Source Subnet 402, including

ColorCode with a value of 7, SecondaryColorCode with values of 8 and 9, and UATIUpdateTriggerTimer T 1. AT 400 requests a PCF 406 to register for a session in Source Subnet 402, and is assigned a UATI. The ColorCode is 7. After a successful registration, AT 400 stores the ColorCode for its source subnet with a value of 7, and transforms to a dormant packet data session state.

AT 400 moves across to Target Subnet 404 in a dormant state, and receives

Sector Parameters sent by Target Subnet 404, which include ColorCode with a value of 8, SecondaryColorCode with a value of 7, and UATIUpdateTriggerTimer with a value of T2. AT 400 determines that ColorCode of AT 400 already stored has a value that is included in SecondaryColorCode of Target Subnet 404 (i.e., 7), and determines Target Subnet 404 ColorCode is not 7. Then, AT 400 initiates a UATI update timer with length of T2.

Before the UATI update timer expires, AT 400 returns back to Source Subnet 402, and receives sector parameters sent by Source Subnet 402, including ColorCode with a value of 7, SecondaryColorCode with values of 8 and 9, and UATIUpdateTriggerTimer with a value of Tl . Since ColorCode already stored by AT 400 has the same value as the ColorCode of Source Subnet 402 just received (i.e., 7), AT 400 stops UATI update timer. However, the AT 400 will not initiate another UATI update timer.

The present invention thus provides signaling between ATs and Access Networks (ANs) that optimizes access performance of the ATs - particularly by reducing communication between subnets. A UATI update may be triggered after an AT moves into a target subnet, from a source subnet. Forward signaling reaches an AT, access delay of the AT is reduced, and wireless communication performance is improved. This ensures that the AT receives forward signaling, shortens call set- up delay.

The previous description of the disclosed embodiments is provided to enable those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art and generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of communication for an access terminal, in a wireless network having a plurality of subnets, the method comprising: determining, as the access terminal in a dormant state moves from a source subnet to a target subnet, whether a ColorCode associated with the source subnet corresponds to a SecondaryColorCode of the target subnet; initiating a Unicast Access Terminal Identifier (UATI) update request from the access terminal to the target subnet if the ColorCode associated with the source subnet does not correspond to the SecondaryColorCode of the target subnet; and providing a method to delay the Unicast Access Terminal Identifier (UATI) update if the

ColorCode associated with the source subnet corresponds to the SecondaryColorCode of the target subnet.

2. The method of claim 1 wherein providing a method to delay the UATl update further comprises: initiating a Unicast Access Terminal Identifier (UATI) update timer; and initiating a Unicast Access Terminal Identifier (UATI) update request from the access terminal to the target subnet if the Unicast Access Terminal Identifier (UATI) update timer expires.

3. The method of claim 2 further comprising defining the Unicast Access Terminal Identifier (UATI) update timer utilizing information sent by the target subnet.

4. The method of claim 3 wherein the information comprises a value of UATIUpdateTriggerTimer in a SectorParameters message sent by the target subnet.

5. The method of claim 4 wherein the value of UATIUpdateTriggerTimer is defined responsive to network payload.

6. The method of claim 4 wherein a default value of the UATIUpdateTriggerTimer is

1800.

7. The method of claim 3 wherein the information comprises a value of time sent by the target subnet, and the UATI update timer is defined using the time sent by the target subnet and the current time of the access terminal.

8. The method of claim 2 further comprising stopping the Unicast Access Terminal Identifier (UATI) update timer if the access terminal moves back to the source subnet before the Unicast Access Terminal Identifier (UATI) update timer expires, wherein the access terminal does not initiate a Unicast Access Terminal Identifier (UATI) update request to the target subnet.

9. The method of claim 2 further comprising resetting and initiating the Unicast Access Terminal Identifier (UATI) update timer if the access terminal moves to a second target subnet before the Unicast Access Terminal Identifier (UATI) update timer expires.

10. The method of claim 9 wherein the Unicast Access Terminal Identifier (UATI) update timer is reset using information sent by the second target subnet.

11. A wireless communications system, comprising: a plurality of subnets; and at least one access terminal; wherein the at least one access terminal is adapted to store ColorCode value of a source subnet within which it is residing; wherein, the at least one access terminal, when moving from the source subnet to a target subnet in a dormant state, is adapted to determine whether a ColorCode associated with the source subnet corresponds to a SecondaryColorCode of the target subnet; wherein the at least one access terminal is adapted to initiate a Unicast Access Terminal Identifier (UATI) update request to the target subnet if the ColorCode associated with the source subnet does not correspond to the SecondaryColorCode of the target subnet; and wherein the at least one access terminal is adapted to provide at least one method to delay the Unicast Access Terminal Identifier (UATI) update in the target subnet if the ColorCode associated with the source subnet does correspond to the SecondaryColorCode of the target subnet.

12. The system of claim 1 1 wherein the at least one method to delay the Unicast Access Terminal Identifier (UATI) update comprises: initiating a Unicast Access Terminal Identifier (UATI) update timer; and initiating a Unicast Access Terminal Identifier (UATI) update request to the target subnet if the Unicast Access Terminal Identifier (UATI) update timer expires.

13. The system of claim 12 wherein the Unicast Access Terminal Identifier (UATI) update timer is defined utilizing information sent by the target subnet.

14. The system of claim 13 wherein the information comprises a value of UATIUpdateTriggerTimer in a SectorParameters message sent by the target subnet.

15. The system of claim 14 wherein the value of UATIUpdateTriggerTimer is defined responsive to network payload.

16. The system of claim 14 wherein a default value of the UATIUpdateTriggerTimer is 1800.

17. The system of claim 13 wherein the information comprises a value of time sent by the target subnet, and the UATI update timer is defined using the time sent by the target subnet and the current time of the at least one access terminal.

18. The system of claim 12 wherein the at least one access terminal is adapted to stop the Unicast Access Terminal Identifier (UATI) update timer if the at least one access terminal moves back to the source subnet before the Unicast Access Terminal Identifier (UATI) update timer expires, wherein the at least one access terminal does not initiate a Unicast Access Terminal Identifier (UATI) update request to the target subnet.

19. The system of claim 12 wherein the at least one access terminal is adapted to reset and initiate the Unicast Access Terminal Identifier (UATI) update timer if the at least one access terminal moves to a second target subnet before the Unicast Access Terminal Identifier (UATI) update timer expires.

20. A method of updating Unicast Access Terminal Identifier (UATI) of an access terminal in a dormant state, in a wireless network having a plurality of subnets, the method comprising: determining, as the access terminal in a dormant state moves from a source subnet to a target subnet, whether a ColorCode associated with the source subnet corresponds to a SecondaryColorCode of the target subnet; initiating a Unicast Access Terminal Identifier (UATI) update request from the access terminal to the target subnet if the ColorCode associated with the source subnet does not correspond to the SecondaryColorCode of the target subnet; initiating a Unicast Access Terminal Identifier (UATI) update timer if the ColorCode associated with the source subnet corresponds to the SecondaryColorCode of the target subnet; wherein a Unicast Access Terminal Identifier (UATI) update request is initiated from the access terminal to the target subnet when the Unicast Access Terminal Identifier (UATI) update timer expires; wherein the Unicast Access Terminal Identifier (UATI) update timer is stopped if the at least one access terminal moves back to the source subnet before the Unicast Access Terminal Identifier (UATI) update timer expires; and wherein the Unicast Access Terminal Identifier (UATI) update timer is reset and initiated if the at least one access terminal moves to a second target subnet before the Unicast Access Terminal Identifier (UATI) update timer expires.