Title of Invention	A METHOD FOR INTER-RAT IDLE 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 idle (dormant) 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.

Title of Invention

A METHOD FOR INTER-RAT IDLE 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 idle (dormant) 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. Further, the present invention relates to the Handoff flows associated on network level between HRPD (EVDO) and 1x networks with use of a hybrid AT in idle mode. More particularly the present invention relates to a method for cross paging and inter-rat idle 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 functions with two independent stacks and no handoff is supported across the two. Therefore when the mobile station (MS) is tuned to HRPD network, it monitors the 1x control channel in both idle and connected states and looks for 1x pages therein. In order to capture a mobile terminated 1x call, the hybrid AT closes the HRPD connection and tunes to 1x network. Thus, instead of handover, the prior art accomplishes switching. Here the coordination between the two networks is established at the HAT level only and therefore the AT looks for both the network messages by doing time multiplexing. It is understood that the current architecture does not confer any direct communication between 1x and HRPD networks and the HAT is made intelligent to have the basic interlocking. Figure 1 gives the current network architecture for a Hybrid Access Terminal (HAT). 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 Location Notification message with the IS-2000 system {SID, NID, PZID} tuple to the HRPD system. Upon losing service on an HRPD system and failing to reacquire an HRPD system, the access terminal performs data session handoff from an HRPD system to an IS-2000 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 (both Idle or connected states). 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, 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 idle (dormant) 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 (IWS). The HRPD network is data specific and hence employs techniques that make it more efficient for this purpose as compared to 1 x. Moreover the newer versions of 1x do employ these better techniques but are not deployed as yet (for eg. Rel 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 main objective of this invention is to facilitate the idle (dormant) handoff between 1x and HRPD networks. Therefore it is the primary object of this invention to provide a method for cross paging and inter- RAT data session handoff between HRPD and CDMA2000 1x networks in dormant (idle) mode. It is 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 yet another object of the invention to provide a method where 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. Accordingly, the invention provides a method for cross paging in a Hybrid Access Terminal (HAT) and inter - RAT idle handoff between networks using an Inter Working Solution (IWS), and the call flows to achieve inter-RAT handoffs in idle (dormant) 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: 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; sending a paging request message to IWS on receiving the said call by Mobile Switching Centre (MSC); processing of the said Paging Request message by IWS and generating an encapsulated PDU containing a General Page Message (GPM); sending the said encapsulated GPM to the AN and then to the HAT acknowledging the receipt of encapsulated GPM message by HAT sending a response message to the IWS by AN so as to indicate that the HAT successfully received the encapsulated GPM; and 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 a Network Architecture with hybrid AT (according to the prior art). Figure 2 shows a Network Architecture (note only signaling interfaces are shown). Figure 3 defines a flow chart where AT connected to HRPD n/w and a voice call received for the AT (Assumption : 1X BSC can process unsolicited pages.). Figure 4 defines a flow chart where AT connected to HRPD n/w and a voice call received for the AT (Assumption : 1X BSC cannot process unsolicited pages.)-Figure 5 shows AT tuned to 1x network, HRPD data call received. 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 H1 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 forwarded 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 A 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 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)ATconnected to HRPD n/w and a voice call received for the AT (Assumption: 1x BSC can process unsolicited pages.) Serving Network: HRPD Redirected to: 1x M1 MSC receives a voice call for the hybrid AT currently registered to the HRPD n/w. MSC sends a Paging Request message to the HRPD AN. 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 IWSSendPrame message. HI 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. A1 The 3G1x Notification application running at AT forwards the GPM to 1x stack and after receiving an indication of acceptance sends Redirection Info informing HRPD AN about its movement to 1x network. H2 The HRPD AN stores the context about movement of AT to 1x network. A2 As there is no connection opened at this stage, AT tunes to 1x and sends PageResponse message (after doing initial checks like overhead ok of 1x system). B1 As 1x BSC is capable of receiving unsolicited page responses (response to a page not sent by this BSC), 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. 2) AT connected to HRPD n/w and a voice call received for the AT (Assumption: 1x BSC cannot process unsolicited pages.) Serving Network: HRPD Redirected to: 1x M1 MSC receives a voice call for the hybrid AT currently registered to the HRPD n/w. 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 fonA^ards the GPM to 1x stack and after receiving an indication of acceptance sends Redirectionlnfo informing HRPD AN about its movement to 1x network. H2 The HRPD AN stores the context about movement of AT to 1x network. A2 As there is no connection opened at this stage, AT tunes to 1X and sends PageResponse message (after doing initial checks like overhead ok of 1x system). 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. 3) AT tuned to 1x network, HRPD data call received. Serving Network: 1x Redirected to: HRPD Precondition: AT is tuned to 1x network but RP connection with PDSN does not exist i.e. AT is in idle state. P1 PDSN receives some data destined for the AT. PDSN sends the GRE packet to HRPD AN. HI HRPD AN finds out that this AT is currently being serviced by 1x, so sends a HRPD Page message to IWS. HRPD AN keeps the knowledge for each AT as to which is the serving system for this. Whenever an AT serviced by HRPD moves to 1x system, it sends Redirectionlnfo message (in idle state) or Connection close (in connected state) with reason set to "movement to 1x". Here the HRPD AN stores the context for this AT as "serviced by 1x". This context changes again to "serviced by HRPD" when it receives connection request from that AT. 11 IWS forms a BS Service Request message. It starts T311 timer. M1 MSC prepares a Paging Request message and forwards it to the 1x BSC with data indicating a HRPD call for the AT. Also, it acknowledges the BS Service Request message by sending BS Service Response message to the IWS 12 Stops T311 timer. B1 1x BSC deciphers the Paging Request and builds GPM with Service Option 59 (Newly added SO to cater for HRPD paging on 1x). A1 AT builds the PageResponse message and sends across to BSC, B2 BSC sends Paging Response message to MSC and sends a release order to AT (an explicit Release order ORDQ can be used to tell the AT that this release is due to movement to HRPD.) M2 Sends Assignment Request message to IWS. Starts timer T10. 13 Prepares HRPD Page Response message and forwards it to HRPD AN. H2 Stores the context for this AT as coming back to HRPD. A2 Stores layer 2 ack for release order. B3 Stores the information that AT is moving to HRPD and from now onwards, for a call for this AT, MSC is to be contacted for paging using HRPD network. AT tunes to 1X and the network (HRPD AN) starts the connection procedures (Refer to C.S00024) to establish a connection till service configuration. H3 Connection Established and now the HRPD AN sends HRPD Connection Complete message to IWS. It sends LocationUpdate Request message to AT. 14 IWS sends AssignmentComplete message to MSC. M3 MSC knows the AT is now in HRPD and not in 1x. Stops timer T10. A3 Sends LocationUpdate Response to HRPD AN giving details of its location. H4 Sends IWSRegistrationInd message to IWS, 15 Sends LocationUpdating Request to MSC. Starts a timer T3210. M4 Store the current updated location info of this AT. Sends Location Updating Accept to IWS. 16 IWS stops timer T3210 sends IWSRegistrationAck to HRPD AN. H5 Stores the context. Data exchange happens between AT and AN. Call closes at HRPD AN. After some idle time, AT tunes back to 1x. A4 AT sends Registration message to BSC. B4 BSC sends LocationUpdating Request to MSC M5 MSC updates the information for this AT and sends across LocationUpdating Accept. B5 Sends Registration ack order to AT. A5 AT is registered to 1x network. When a hybrid AT is monitoring HRPD system, 3G1x Notification Service is enabled and the 1x MSC after deciding that has 1x data (SMS or page for a call) for the AT sends a ADDS Page message to IWS. 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. Glossary of Terms and their definitions HRPD: High Rate Packet Data network defined as per C.S0024 standard of 3GPP2. 1X : CDMA 2000 network defined as per C.S0002 to C.S0006 standards of 3GPP2. AN : Access Network BSC : Base Station Controller (used in 1x network for Access network) MSC : Mobile Switching Centre AT : Access Terminal, same as the Mobile terminal of CDMA2000. Hybrid AT : An AT that supports both HRPD and 1x. PDSN : Packet Data Switching Node. IWF : Inter Working Function. RAT: Radio Access Technology. Examples: CDMA2000, GSM, UMTS, 4G etc WE CLAIM 1. A method for cross paging in a Hybrid Access Terminal (HAT) and inter- RAT idle handoff between networks using an Inter Working Solution (IWS), and the call flows to achieve inter-RAT handoffs in idle (dormant) 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 acknowledging the receipt of encapsulated GPM message by HAT sending a response message to the IWS by AN so as to indicate that the HAT successfully received the encapsulated GPM; and (e) 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. I. 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 dormant mode. :.The method of claim 1, wherein MSC queries and updates the network element (HLR) for serving RAT and network details for the AT. i.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 idle 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 connected to HRPD network and a voice call received for the AT and wherein the BSC can process unsolicited pages-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 connected to HRPD network and a voice call received for the AT and wherein the 1x BSC cannot process unsolicited pages as described and illustrated with reference to the accompanying figure 4. 17. A method according to claim 1 and the call flows when the HAT is tuned to 1x network, HRPD data call received as described and illustrated with reference to the accompanying figure 5.

Full Text

FIELD OF INVENTION
This invention in general relates to mobile communication techniques in networks such as CDMA and HRPD. Further, the present invention relates to the Handoff flows associated on network level between HRPD (EVDO) and 1x networks with use of a hybrid AT in idle mode. More particularly the present invention relates to a method for cross paging and inter-rat idle 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 functions with two independent stacks and no handoff is supported across the two. Therefore when the mobile station (MS) is tuned to HRPD network, it monitors the 1x control channel in both idle and connected states and looks for 1x pages therein. In order to

capture a mobile terminated 1x call, the hybrid AT closes the HRPD connection and tunes to 1x network. Thus, instead of handover, the prior art accomplishes switching. Here the coordination between the two networks is established at the HAT level only and therefore the AT looks for both the network messages by doing time multiplexing. It is understood that the current architecture does not confer any direct communication between 1x and HRPD networks and the HAT is made intelligent to have the basic interlocking. Figure 1 gives the current network architecture for a Hybrid Access Terminal (HAT).
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 Location Notification message with the IS-2000 system {SID, NID, PZID} tuple to the HRPD system. Upon losing service on an HRPD system and failing to reacquire an HRPD system, the access terminal performs data session handoff from an HRPD system to an IS-2000 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 (both Idle or connected states).
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, 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 idle (dormant) 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 (IWS).
The HRPD network is data specific and hence employs techniques that make it more efficient for this purpose as compared to 1 x. Moreover the newer versions of 1x do employ these better techniques but are not deployed as yet (for eg. Rel 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 main objective of this invention is to facilitate the idle (dormant) handoff between 1x and HRPD networks. Therefore it is the primary object of this invention to provide a method for cross paging and inter- RAT data session handoff between HRPD and CDMA2000 1x networks in dormant (idle) mode.
It is 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 yet another object of the invention to provide a method where 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.
Accordingly, the invention provides a method for cross paging in a Hybrid Access Terminal (HAT) and inter - RAT idle handoff between networks using an Inter Working Solution (IWS), and the call flows to achieve inter-RAT handoffs in idle (dormant) 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: 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; sending a paging request message to IWS on receiving the said call by Mobile Switching Centre (MSC); processing of the said Paging Request message by IWS and generating an encapsulated PDU containing a General Page Message (GPM); sending the said encapsulated GPM to the AN and then to the HAT acknowledging the receipt of encapsulated GPM message by HAT sending a response message to the IWS by AN so as to indicate that the HAT successfully received the encapsulated GPM; and 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 a Network Architecture with hybrid AT (according to the prior art).
Figure 2 shows a Network Architecture (note only signaling interfaces are shown).
Figure 3 defines a flow chart where AT connected to HRPD n/w and a voice call received for the AT (Assumption : 1X BSC can process unsolicited pages.).

Figure 4 defines a flow chart where AT connected to HRPD n/w and a voice call received for the AT (Assumption : 1X BSC cannot process unsolicited pages.)-Figure 5 shows AT tuned to 1x network, HRPD data call received.
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
H1 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 forwarded 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 A 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 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)ATconnected to HRPD n/w and a voice call received for the AT (Assumption: 1x BSC can process unsolicited pages.) Serving Network: HRPD Redirected to: 1x
M1 MSC receives a voice call for the hybrid AT currently registered to the HRPD n/w. MSC sends a Paging Request message to the HRPD AN. 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 IWSSendPrame message.
HI 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.

A1 The 3G1x Notification application running at AT forwards the GPM to 1x stack and after receiving an indication of acceptance sends Redirection Info informing HRPD AN about its movement to 1x network.
H2 The HRPD AN stores the context about movement of AT to 1x network. A2 As there is no connection opened at this stage, AT tunes to 1x and sends PageResponse message (after doing initial checks like overhead ok of 1x system). B1 As 1x BSC is capable of receiving unsolicited page responses (response to a page not sent by this BSC), 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.
2) AT connected to HRPD n/w and a voice call received for the AT (Assumption: 1x BSC cannot process unsolicited pages.) Serving Network: HRPD Redirected to: 1x
M1 MSC receives a voice call for the hybrid AT currently registered to the HRPD n/w. 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 fonA^ards the GPM to 1x stack and after receiving an indication of acceptance sends Redirectionlnfo informing HRPD AN about its movement to 1x network.
H2 The HRPD AN stores the context about movement of AT to 1x network. A2 As there is no connection opened at this stage, AT tunes to 1X and sends
PageResponse message (after doing initial checks like overhead ok of 1x
system). 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.
3) AT tuned to 1x network, HRPD data call received. Serving Network: 1x Redirected to: HRPD
Precondition: AT is tuned to 1x network but RP connection with PDSN does not exist i.e. AT is in idle state.
P1 PDSN receives some data destined for the AT. PDSN sends the GRE packet to HRPD AN.
HI HRPD AN finds out that this AT is currently being serviced by 1x, so sends a HRPD Page message to IWS. HRPD AN keeps the knowledge for each AT as to which is the serving system for this. Whenever an AT serviced by HRPD moves to 1x system, it sends Redirectionlnfo message (in idle state) or Connection close (in connected state) with reason set to "movement to 1x". Here the HRPD AN stores the context for this AT as "serviced by 1x". This context changes again to "serviced by HRPD" when it receives connection

request from that AT.
11 IWS forms a BS Service Request message. It starts T311 timer.
M1 MSC prepares a Paging Request message and forwards it to the 1x BSC with data indicating a HRPD call for the AT. Also, it acknowledges the BS Service Request message by sending BS Service Response message to the IWS
12 Stops T311 timer.
B1 1x BSC deciphers the Paging Request and builds GPM with Service Option
59 (Newly added SO to cater for HRPD paging on 1x). A1 AT builds the PageResponse message and sends across to BSC, B2 BSC sends Paging Response message to MSC and sends a release order
to AT (an explicit Release order ORDQ can be used to tell the AT that this
release is due to movement to HRPD.) M2 Sends Assignment Request message to IWS. Starts timer T10.
13 Prepares HRPD Page Response message and forwards it to HRPD AN.
H2 Stores the context for this AT as coming back to HRPD.
A2 Stores layer 2 ack for release order.
B3 Stores the information that AT is moving to HRPD and from now onwards, for
a call for this AT, MSC is to be contacted for paging using HRPD network.
AT tunes to 1X and the network (HRPD AN) starts the connection procedures (Refer to C.S00024) to establish a connection till service configuration.
H3 Connection Established and now the HRPD AN sends HRPD Connection Complete message to IWS. It sends LocationUpdate Request message to AT.
14 IWS sends AssignmentComplete message to MSC.
M3 MSC knows the AT is now in HRPD and not in 1x. Stops timer T10.
A3 Sends LocationUpdate Response to HRPD AN giving details of its location.
H4 Sends IWSRegistrationInd message to IWS,
15 Sends LocationUpdating Request to MSC. Starts a timer T3210.
M4 Store the current updated location info of this AT. Sends Location Updating

Accept to IWS. 16 IWS stops timer T3210 sends IWSRegistrationAck to HRPD AN. H5 Stores the context.
Data exchange happens between AT and AN. Call closes at HRPD AN. After some idle time, AT tunes back to 1x.
A4 AT sends Registration message to BSC.
B4 BSC sends LocationUpdating Request to MSC
M5 MSC updates the information for this AT and sends across LocationUpdating
Accept. B5 Sends Registration ack order to AT. A5 AT is registered to 1x network.
When a hybrid AT is monitoring HRPD system, 3G1x Notification Service is enabled and the 1x MSC after deciding that has 1x data (SMS or page for a call) for the AT sends a ADDS Page message to IWS.
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.

Glossary of Terms and their definitions
HRPD: High Rate Packet Data network defined as per C.S0024 standard of
3GPP2.
1X : CDMA 2000 network defined as per C.S0002 to C.S0006 standards of 3GPP2.
AN : Access Network
BSC : Base Station Controller (used in 1x network for Access network)
MSC : Mobile Switching Centre
AT : Access Terminal, same as the Mobile terminal of CDMA2000.
Hybrid AT : An AT that supports both HRPD and 1x.
PDSN : Packet Data Switching Node.
IWF : Inter Working Function.
RAT: Radio Access Technology. Examples: CDMA2000, GSM, UMTS, 4G etc

WE CLAIM
1. A method for cross paging in a Hybrid Access Terminal (HAT) and inter- RAT
idle handoff between networks using an Inter Working Solution (IWS), and the
call flows to achieve inter-RAT handoffs in idle (dormant) 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 acknowledging the receipt of encapsulated GPM message by HAT sending a response message to the IWS by AN so as to indicate that the HAT successfully received the encapsulated GPM; and
(e) 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.
I. 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 dormant mode.
:.The method of claim 1, wherein MSC queries and updates the network element (HLR) for serving RAT and network details for the AT.
i.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 idle 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 connected to HRPD network and a voice call received for the AT and wherein the BSC can process unsolicited pages-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 connected to HRPD network and a voice call received for the AT and wherein the 1x BSC cannot process unsolicited pages as described and illustrated with reference to the accompanying figure 4.
17. A method according to claim 1 and the call flows when the HAT is tuned to 1x network, HRPD data call received as described and illustrated with reference to the accompanying figure 5.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=Ji4LF7yIQ7cAqFDPMYYSoA==&loc=egcICQiyoj82NGgGrC5ChA==

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Patent Number

270044

Indian Patent Application Number

1201/CHE/2004

PG Journal Number

48/2015

Publication Date

27-Nov-2015

Grant Date

26-Nov-2015

Date of Filing

16-Nov-2004

Name of Patentee

SAMSUNG R& D INSTITUTE INDIA BANGALORE PRIVATE LIMITED

Applicant Address

#2870 ORION BUILDING BAGMANE CONSTELLATION BUSINESS PARK OUTER RING ROAD DODDANEKUNDI CIRCLE MARATHAHALLI POST BANGALORE -560037

Inventors:

#	Inventor's Name	Inventor's Address
1	RICHA,DHAM	BAGMANE LAKEVIEW,BLOCK 'B',NO.66/1,BAGMANE TECH PARK,C V RAMAN NAGAR,BYRASANDRA,BANGALORE-560093

PCT International Classification Number

g 01 b 01/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA