Title of Invention

A METHOD FOR INTER-RAT ACTIVE SESSION HANDOFF BETWEEN HRPD AND CDMA2000 1X NETWORKS

Abstract

The present invention proposes to eliminate the drawbacks of the prior art using a method, which facilitates cross paging and active session handoff between 1x and HRPD networks for a multi mode (hybrid) AT operating between HRPD and CDMA2000 1x networks, depending on the MS RAT capabilities, MS location, Network condition (Pilot strength etc.), RAT coverage profile etc. suitably analysed and interpreted by an Inter Working Solution (IWF). The HRPD network is data specific and hence employs techniques that make it more efficient for this purpose as compared to 1x. HRPD and 1X are already developed and deployed and hence inter-working between the two is faster to deploy. In this communication system AT knows about the RAT deployment in its service area and Mobile Switching Centre (MSC) knows the serving RAT and network details for the AT. This method proposes an inter-working solution (IWS) which has the intelligence to decipher the 1x pilot information for translating 1x messages in CDMA2000 LAC format and to interpret the interface with MSC viz. A 1 interface. MSC can talk to HRPD Access Network via IWS and can query/update the network element (HLR) for serving RAT and network details for the AT.

Full Text

FIELD OF INVENTION This invention in general relates to mobile communication techniques in networks such as CDMA and HRPD. Particularly the invention relates to the Handoff flows associated on network level between HRPD (EVDO) and 1x networks with use of a hybrid AT in connected state. More accurately the present invention relates to a method for inter-RAT active session handoff between HRPD and CDMA2000 1x networks. DESCRIPTION OF THE RELATED ART The advent of hybrid access terminal (HAT) has created a revolution in the field of telecommunication. Hybrid ATs can support a wide range of Radio Access Technologies (RAT) such as CDMA2000. GSM, UMTS, 4G etc. Present invention takes in to account of a hybrid AT that supports both HRPD and CDMA 2000 1x that are deployed widely in many parts of the world. HRPD (High Rate Packet Data network) is defined as per C.S0024 standard of 3GPP2 and CDMA 2000 1X network is defined as per C.S0002 to C.S0006 standards of 3GPP2. The advantages of HRPD are high data rate and the flexibility for customization to increase its efficiency to cater for data only. On the other hand 1x is mostly employed for voice services but supports data also. If the best features of both can be utilized in the deployed areas then a better service can be provided to the end users. For transparent and seamless movement for the end user, handoff between HRPD and 1x network is to be facilitated. This invention unveils architecture for facilitating handoff and cross paging between CDMA2000 and HRPD networks. The current hybrid AT supporting both 1x and HRPD standards work as two independent stacks and no handoff is supported across the two. Thus when AT is tuned to HRPD network, it looks for 1x pages on the 1x Control Channel. For a Mobile Terminated 1x call, the hybrid AT closes the HRPD connection and tunes to 1x network. Thus instead of handover, switching is accomplished in this method. This is illustrated below. IxtoDO When the AT moves to HRPD network coverage (AT decides it depending on pilot strength measurement), it tunes to HRPD network. To handoff the PDSN data connection from an IS-2000 system to an HRPD system, the access terminal transmits an unsolicited LocationNotification message with the IS-2000 system {SID, NID, PZID} tuple to the HRPD system. DOtdx The access terminal performs data session handoff from an HRPD system to an IS-2000 system upon losing service on an HRPD system and failing to reacquire an HRPD system. To handoff the PDSN data connection from an HRPD system to an IS-2000 system, the access terminal transmits an Origination message with the DRS bit set to zero to the IS-2000 system. Also, the AT monitors the 1x Control Channel when tuned to HRPD network and on receiving the page message from 1x tunes to x network to receive the call. Even though the inter-RAT communication is made possible by the prior art method this approach has its own limitations and disadvantages. The following are the limitations in the existing art. 1. MS is required to monitor 1x Control Channel whenever operating in the HRPD mode even in the connected state. 2. No method is available to inform the network of the movement to the other network. 3. The information of other system pilots is not communicated to the network. 4. The pilots, which are already measured are not utilized between AT and HRPD for active session handoff. 5. There is no mechanism to get HRPD page when AT is tuned to 1x system. The present invention proposes to eliminate the drawbacks of the prior art using a method, which facilitates cross paging and active session handoff between 1x and HRPD networks for a multi mode (hybrid) AT operating between HRPD and CDMA2000 1x networks, depending on the MS RAT capabilities, M6 location, Network condition (Pilot strength etc.), RAT coverage profile etc. suitably are analysed and interpreted by an Inter Working Solution (IWS). The HRPD network is data specific and hence employs techniques that make it more efficient for this purpose as compared to 1x. Moreover the newer versions of 1x do employ these better techniques but are not deployed as yet (for eg. Re! C or EVDV). HRPD and 1X are already developed and deployed and hence inter-working between the two is faster to deploy. SUMMARY OF THE INVENTION The primary object of this invention is therefore to provide a method for cross paging and inter- RAT active session handoff between HRPD and CDMA2000 1x networks in Connected mode. It is another object of the invention to provide a method for inter-RAT handovers and active session hand off in wireless domain for multi mode AT depending on the MS RAT capabilities, MS location. Network condition (Pilot strength etc.), RAT coverage profile etc. It is yet another object of the invention to provide a communication system where AT knows about the RAT deployment in its service area and Mobile Switching Centre (MSC) knows the serving RAT and network details for the AT with the help of an inter working solution (IWS) which has the intelligence to decipher the 1x pilot information for translating 1x messages in CDMA2000 LAC format and to interpret the interface with MSC viz. A1 interface. It is also an object of the invention to provide a system where MSC talks to HRPD Access Network via IWS and can queries and updates the network element (HLR) for serving RAT and network details for the AT. The invention relates in general to inter-RAT handovers in wireless domain and in particular to handoff between HRPD and 1x networks when hybrid AT is in connected mode. Accordingly, the invention provides a method for cross paging in a Hybrid Access Terminal (HAT) and inter- RAT active session handoff between networks using an Inter Working Solution (IWS), and the call flows to achieve inter-RAT handoffs in active (connected) state of Hybrid AT, where the architecture comprises an Inter Working Solution and a new interface H1 between Mobility Management entity of HRPD AN and IWS, the communication method comprising the steps of: a) receiving an in-coming call for the Hybrid Access Terminal (HAT) that is tuned to an Access Network (AN) and is under the control of the IWS; b) sending a paging request message to IWS on receiving the said call by Mobile Switching Centre (MSC); c) processing of the said Paging Request message by IWS and generating an encapsulated PDU containing a General Page Message (GPM); d) sending the said encapsulated GPM to the AN and then to the HAT e) acknowledging the receipt of encapsulated GPM message by HAT f) sending a response message to the IWS by AN so as to indicate that the HAT successfully received the encapsulated GPM; and g) sending a Paging Response message to the MSC by IWS These and other objects, features and advantages of the present invention will become clearly apparent from the following description of the embodiments of the invention given as non-restrictive example only and represented in the accompanying drawings. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 shows the Network Architecture with hybrid AT. Figure 2 shows the Network Architecture (note only signaling interfaces are shown). Figure 3 illustrates where AT is tuned to HRPD and connection is opened with PDSN and a voice call received at MSC. Figure 4 shows AT talking on 1x (Voice), receives data call on HRPD. DETAILED DESCRIPTION OF THE INVENTION The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail. The invention introduces a new entity called IWS (Inter Working Solution) as part of the HRPD RAN. The IWS interfaces to the MSC via an lOS A1 interface, and also to the SC/MM via a new interface called H1 interface. The IWS entity would fit in either the TIA-878 or the TIA-1878 architecture. Accordingly the present invention further relates to a method for inter RAT idle handoff for multi mode AT where IWS talks to HRPD AN (SC/MM) via H1 interface and where IWS has the intelligence to interpret interface with MSC (A1 interface). The new architecture entities are detailed below. IWS (Inter-Working Solution): This entity is made as a part of the HRPD RAN and it interfaces to the MSC via an lOS A1 interface, and also to the SC/MM (Session Control/ Mobility Management) via a new interface called H1 interface. The SC/MM may be located in either the AN or the PCF (Packet Control Function) in the HRPD RAN. The primary function of the IWS is to translate A1 messages to CDMA2000 LAC messages, which are then sent to the SC/MM for eventual transmission to the HAT. If the SC/MM is located in the AN, then AN will send the message directly to the HAT using the 3G1x Services Notification Application protocol. If the SC/MM is in the PCF, the SC/MM must first send the CDMA2000 LAC message to the AN over the A14 interface. Likewise, messages received from the HAT (such as Connection Request messages) by the AN may result in the SC/MM sending update messages to the IWS; the IWS may then send an A1 interface message (e.g. Location Updating Request) to the MSC. HI Interface: It is a new interface incorporated between the IWS and the SC/MM. The protocol stack is based on TCP/IP with an lOS layer above that. This IP-based interface connects the IWS to the SC/MM in the HRPD architecture and carries 3G1X LAC encapsulated PDUs in an lOS-defined protocol. Messages carry the encapsulated 3G LAC messages for delivery to the SC/MM and information from the SC/MM to the IWS. The H1 interface is an IP-based interface. The Figure 2 shows the protocol stacks for the architecture based on TIA-878. A similar figure can be created for the architecture based on TIA-1878; the only change would be that the SC/MM would be in the PCF, and there would be an A14 interface between the PCF and the AN. The new entity viz IWS (Inter Working Solution), works as the gateway and translator for HRPD network. The 1x network entity viz. MSC sees this IWS as another 1x BSC and pushes relevant messages/data to it. The IWS translates the A1 interface data to one that is understood by HRPD AN (SC/MM entity). The messages from 1x are interpreted by IWS and fon/varded to HRPD AN for final delivery to Hybrid AT over HRPD air interface. Similarly messages/data to be sent to 1x network is routed through the IWS and are translated from HRPD format to an interface format. The sections below give the details of call flows involved in achieving idle handoff between HRPD and 1X systems. Each step is identified by two a letter and numeric like Xn, where X can take on following values. Here n is a numeric value stating the nth step at that node. For e.g. A2 means step 2 at hybrid AT in the call context. A Hybrid AT H HRPD AN M 1xMSC P PDSN B 1xBSC 1 IWS Let us see the different call flows 1) AT is tuned to HRPD and connection is opened with PDSN and a voice call received at MSC Serving Network: HRPD Redirected to: 1x M1 MSC receives a voice call for the hybrid AT currently registered to the HRPD n/\N. MSC sends a Paging Request message to the HRPD AN and 1x BSC. MSC starts T3113 timer. 11 The IWS module takes care of the page received and prepares a 1x LAC PDU containing 1x-L3 General Page Message (GPM). It encapsulates the 1x LAC PDU in IWSSendFrame message. H1 3G1x service notification application extracts 1x LAC PDU (GPM) from IWSSendFrame message and builds 3G1x packet and sends across to AT over HRPD air interface. B1 Just registers the Paging Request as it is unable to process unsolicited pages. A1 The 3G1x Notification application running at AT forwards the GPM to 1x stack and after receiving an indication of acceptance sends ConnectionClose message informing HRPD AN about its movement to 1x network and closing the current connection. Sends an indication back to 1x stack running at AT to start the movement to 1x. H2 Sends A11 RegistrationReq to PDSN with StopAirlinkRecord. P1 Stores the information for the session. A2 AT tunes to 1X and sends PageResponse message (after checking Overhead_OK). B2 As 1x BSC is not capable of receiving unsolicited page responses (response to a page not sent by this BSC), but has the information about this page, it processes the message and sends across Paging Response encapsulated in L3 Complete Info message to MSC. M2 MSC stops the T3113 timer after receiving Paging Response. Connection setup procedures for 1x are carried out (including the service negotiation). 2) The AT Is tuned to 1X network and a voice call is on. The data call context still lies between HRPD AN and PDSN. P1 PDSN has data for the AT and hence sends the GRE packet over A10 interface to the HRPD AN H1 HRPD AN finds out that this AT is currently being serviced by 1x, so sends a HRPD Page message to IWS. 11 IWS forms a BS Service Request message. M1 MSC finds out that this AT is already on a call and thus sends an "Additional Service notification" to 1x BSC with service option S059. MSC starts timer T314. B1 IX BSC constructs the Additional Service Request message, sends the message to the MSC. and starts timer T303. M2 The MSC stops timer T314 upon receipt of the Additional Service Request message from the BS. The MSC sends an Assignment Request message to the BSC to request assignment of radio resources. The MSC then starts timer T10. B2 Stops timer T303 on receipt of Assignment request Message from MSC. The BSC sends a Call Assignment Message over the traffic channel of the radio interface to initiate establishment of a CC state machine. BSC sends assignment complete message to MSC. M3 MSC notes that this AT is moving to HRPD (required to initiate Location updating procedures). A2 MS finds out that the call is from HRPD network and hence sends the release order to 1x BSC indicating movement to HRPD network. B3 Sends a BS Ack order to the AT. Sends Location Updating Request message to MSC. Starts a timer T3210. M4 Replies back with Location Updating Accept message to 1x BSC. B4 Stops the timer T3210. AT tunes to DO and connection establishment procedures are carried out till service negotiation. H2 Sends IWSRegistrationInd message to IWS. 12 Sends LocationUpdating Request to MSC. Starts a timer T3210. M5 Replies back with Location Updating Accept message to IWS. 13 Stops the timer T3210. IWS sends IWSRegistrationAck message to HRPD AN. H3 Stores the context. Data exchange happens with HRPD AN. It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is therefore omitted above. It should also be noted that the host for storing the applications include but not limited to a computer, mobile communication device, mobile server or a multi function device. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart there from. WE CLAIM 1. A method for cross paging in a Hybrid Access Terminal (HAT) and inter- RAT active session handoff between networks using an Inter Working Solution (IWS), and the call flows to achieve inter-RAT handoffs in active (connected) state of Hybrid AT, where the architecture comprises an Inter Working Solution and a new interface H1 between Mobility Management entity of HRPD AN and IWS, the communication method comprising the steps of: a) receiving an in-coming call for the Hybrid Access Terminal (HAT) that is tuned to an Access Network (AN) and is under the control of the IWS; b) sending a paging request message to IWS on receiving the said call by Mobile Switching Centre (MSC); c) processing of the said Paging Request message by IWS and generating an encapsulated PDU containing a General Page Message (GPM); d) sending the said encapsulated GPM to the AN and then to the HAT e) acknowledging the receipt of encapsulated GPM message by HAT f) sending a response message to the IWS by AN so as to indicate that the HAT successfully received the encapsulated GPM; and g) sending a Paging Response message to the MSC by IWS. 2. The method according to claim 1, where IWS is a new logical entity. 3. The method according to claim 1 wherein the networks are HRPD and CDMA2000 1x. 4. The method according to any of the preceding claims wherein IWS talks to HRPD AN (SC/MM) via H1 interface. 5. The method according to claim 1 wherein the HAT is tuned to HRPD. 6. The method according to claim 1 wherein the said paging request message contains calling party number. The method according to claim 1 wherein the said General Page Message (GPM) is 3G1X LAC encapsulated. The method according to claim 7 wherein the said GPM contains calling party number. The method according to claim 1 wherein the Access Network (AN) sends the GPM to the HAT over the TIA-878-A air interface using the 3G 1x Circuit Services Notification Application protocol. A method according to claim 1 wherein the said inter-RAT handoff depends on the MS RAT capabilities, MS location, Pilot strength and RAT coverage profile. The method according to claim 1, wherein the HAT moves from HRPD network coverage to 1x network in active mode. The method of claim 1, wherein MSC queries and updates the network element (HLR) for serving RAT and network details for the AT. The method of claim 13, where IWS translates CDMA2000 1x messages in CDMA2000 LAC format. A method for cross paging in a Hybrid Access Terminal (HAT) and inter- RAT active session handoff between networks using an Inter Working Solution (IWS), the architecture comprising an Inter Working Solution and a new interface H1 between Mobility Management entity of HRPD AN and IWS, substantially herein above described and illustrated with reference to the accompanying drawings. A method according to claim 1 and the call flows when the HAT is tuned to HRPD and connection is opened with PDSN and a voice call received at MSC as described and illustrated with reference to the accompanying figure 3. 16. A method according to claim 1 and the call flows when the HAT is tuned to 1X network and a voice call is on and the data call context still lies between HRPD AN and PDSN as described and illustrated with reference to the accompanying figure 4.

Documents:

1202-CHE-2004 AMENDED PAGES OF SPECIFICATION 26-10-2012.pdf

1202-CHE-2004 AMENDED CLAIMS 26-10-2012.pdf

1202-CHE-2004 EXAMINATION REPORT REPLY RECEIVED 26-10-2012.pdf

1202-CHE-2004 FORM-13 26-10-2012.pdf

1202-CHE-2004 OTHER PATENT DOCUMENT 26-10-2012.pdf

1202-CHE-2004 POWER OF ATTORNEY 26-10-2012.pdf

1202-CHE-2004 FORM-13 19-06-2006.pdf

1202-che-2004-abstract.pdf

1202-che-2004-claims.pdf

1202-che-2004-correspondnece-others.pdf

1202-che-2004-description(complete).pdf

1202-che-2004-description(provisional).pdf

1202-che-2004-drawings.pdf

1202-che-2004-form 1.pdf

1202-che-2004-form 13.pdf

1202-che-2004-form 26.pdf

1202-che-2004-form 5.pdf