Network-based migrating user agent for personal communication services

• US 6,085,086 A
• Filed: 06/27/1997
• Issued: 07/04/2000
• Est. Priority Date: 08/22/1995
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Ramjee, Ramachandran, Veeraraghavan, Malathi, La Porta, Thomas F.
• Primary Examiner(s): Bost, Dwayne D.
• Assistant Examiner(s): MAUNG, NAY AUNG
• Application Number:
  US08/884,105
• Time in Patent Office: 1,103 Days
• Field of Search: 455/414, 455/417, 455/422, 455/432, 455/433, 455/436, 455/461, 455/466, 455/556, 455/557, 370/496, 370/522
• US Class Current: 455/432.3
• CPC Class Codes: G06F 9/4856 resumption being on a different machine, e.g. task migration, virtual machine migration G06F9/5088 takes precedence
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/0019 adapted for mobile IP [MIP]
• CPC Class Codes: H04W 76/20 Manipulation of established connections
• CPC Class Codes: H04W 88/182 Network node acting on behalf of an other network entity, e.g. proxy

Abstract

The present invention is a user process that resides in network nodes to act as an agent for mobile terminals in, for example, PCS environments. The user process handles negotiation and complex signaling functions for the user, thus reducing the amount of signaling traffic that must travel over the valuable air interface. To achieve low call establishment times the user process is migrated as user move. Three embodiment is adapted to enable data sizes which are to be transferred to be optimized, leading to low overhead. This approach also provides flexibility when migrating across heterogeneous environments. A second alternative embodiment may be advantageously utilized when a program is compute intensive and asynchronous migration is essential. The third embodiment provides high reliability in the form of checkpointing, but incurs a high migration delay and has high memory requirement for network processors.

Claims

1. A method of call processing in a communications network, said network including mobile stations adapted for wireless communication with nodes in a fixed portion of said network, said method comprising the steps of:

establishing at least one user agent, each user agent being operative to mimic signaling functions of an associated one of said mobile stations and being disposed at a signaling server operated at a node in said fixed portion of said network, said node being in wireless communications with said mimicked mobile station;

causing said user agent to interface with one or more other nodes in said network in behalf of said mimicked mobile station, for negotiation of signaling parameters in respect to a communications link to be established between said mobile station and said one or more other nodes; and

upon movement of said mimicked mobile station from a first region, wherein wireless communication is maintained with a first signalling server having said user agent disposed thereat, to a second region wherein wireless communication is maintained with a second signaling server operated at another of said nodes in said fixed portion of said network, migrating said user agent to said second signaling server.

2. The method of claim 1, wherein said user agent maintains an operating profile and call state information pertaining to said mimicked mobile station.

3. The method of claim 1, wherein operating parameters of said user agent are preserved upon migrating said user agent to said second signaling server.

4. The method of claim 1, wherein a user process associated with said user agent is anchored at said user signaling server.

5. The method of claim 4, wherein said network includes one or more radio ports to enable wireless communication with said mobile station, further including the step of updating said radio ports with a location of said user agent as said mobile station associated with said user agent moves.

6. The method of claim 4, wherein said network includes one or more radio ports to enable wireless communication with said mobile station, wherein signaling links are established between said radio ports and a user signaling server in which said user agent is resident as said mobile station moves throughout said network.

7. The method of claim 1, wherein said network includes at least one location server for tracking the location of a mobile station within said network, said method further including the steps of:

generating a registration message from said mobile station to said location server upon movement from said first region to said second region, wherein said location server signals to said second user signaling server to migrate said user agent of said mobile station.

8. The method of claim 7, including the steps of requesting and receiving user agent profile parameters at said second user signaling server from said first user signaling server.

9. The method of claim 1, further including the step of maintaining a stub process at said first user signaling server to act in place of said user agent to buffer messages for said user agent during migration.

10. The method of claim 9, wherein said stub process exits after a predetermined idle time-out period.

11. The method of claim 9, wherein said user agent requests buffered information from said stub process once located at said second user signaling server, wherein normal processing by said agent is subsequently resumed.

12. The method of claim 2, wherein said user agent is updated about a current state of said mobile station and carries out call processing functions including call acceptance, call rejection call forwarding, mobile call termination status processing and compatibility checking of data transmissions.

13. The method of claim 2, wherein said user agent is a user process and said step of migrating further includes the steps of:

executing a new user process at said second user signaling server;

establishing a communications connection between a previous user process at said first user signaling server and said new user process;

transferring a data structure containing migration variables from said previous user process;

establishing communication channels at said new user process;

maintaining said previous user process as a stub process; and

forwarding messages received during migration to said new user process.

14. The method of claim 13, wherein said data structure includes call connection data and current state data elements of said mobile station.

15. The method of claim 14, wherein said call connection data is selected from the group consisting of number of users, identification of users, call type, call forwarding and mobile call termination status.

16. The method of claim 14, wherein said current state data elements of said mobile terminal include compatibility checking procedures and applications being run at said mobile station.

17. The method of claim 1, wherein said user agent is a user process and said step of migrating further includes the steps of:

starting a new user process at said second user signaling server; and

copying stack and data pages onto said second user signaling server, wherein said new user process may begin operation.

18. A method of call processing in a communications network, said network including mobile stations adapted for wireless communication, said method comprising the steps of:

registering a mobile station with said network, wherein an individual user agent is established in response to registration of said mobile station at a signaling server within said network, and wherein said user agent is associated with said mobile station and includes an operating profile thereof; and

utilizing said user agent in conjunction with said operating profile to handle call processing functions at said signaling server on behalf of said mobile station to thereby reduce signaling loads over an air interface of said communications network and further including the step of migrating said user agent from a first user signaling server in a first region of said network to a second user signaling server in a second region of said network in response to a move by said mobile station from said first region to said second region, wherein said step of migrating includes,

stopping and saving data register contents of a first user process on said first user signaling server at a source node;

transferring arguments and environment of said first user process to said second user signaling server;

creating a stub process to buffer incoming messages to said first user process;

executing a new user process on a target node at said second user signaling server with said arguments and environment obtained from said user signaling server of said source node;

calculating data and stack sizes of said first user process in migration at said first user signaling server of said source node;

transferring said data and stack sizes to said target user signaling server to thereby enable said new user process to expand its stack and data pages;

transferring and writing said data pages onto said new user process executing on said target user signaling server;

transferring and writing said stack pages;

establishing communication channels at said new user process;

sending a message from said new user process to said stub process and receiving outstanding messages that have been buffered; and

transferring said register contents, wherein said new user process restarts from where it was interrupted.

19. A method of call processing in a communications network, said network including mobile stations adapted for wireless communication, said method comprising the steps of:

registering a mobile station with said network, wherein an individual user agent is established in response to registration of said mobile station at a signaling server within said network, and wherein said user agent is associated with said mobile station and includes an operating profile thereof; and

utilizing said user agent in conjunction with said operating profile to handle call processing functions at said signaling server on behalf of said mobile station to thereby reduce signaling loads over an air interface of said communications network and further including the step of migrating said user agent from a first user signaling server in a first region of said network to a second user signaling server in a second region of said network in response to a move by said mobile station from said first region to said second region, wherein said step of migrating includes,

sending a stop signal from a target user signaling server to said first user process;

creating a child stub process that buffers messages sent to said first user process;

executing a save register command from a target user process to save registers and a core dump in a buffer;

transferring data and stack pages from said core to said target user signaling server;

creating a new user process at said target user signaling server using a text segment from an executable present at an associated node, and with stack and data segments received from said first user signaling server;

establishing communication channels at said new user process;

sending a message from said new user process to said stub process and receiving outstanding messages that have been buffered; and

executing a restore registers command at said new user process to enable continued execution from a point where said user process began migration.

20. A communications apparatus for use in a network including mobile stations adapted for wireless communication with nodes in a fixed portion of said network, said apparatus comprising:

means for establishing a user agent operative to mimic signaling functions of one of said mobile stations and disposed at a signaling server operated at a node in said fixed portion of said network, said node being in wireless communications with said one of said mobile stations;

means for providing an interface between said user agent and one or more other nodes in said network in behalf of said mimicked mobile station, for negotiation of signaling parameters in respect to a communications link to be established between said mobile station and said one or more other nodes; and

means for effecting a migration of said user agent from a first signalling server in a first region to a target signaling server in a second region upon movement of said mimicked mobile station from said first region to said second region.

21. The apparatus of claim 20, wherein said user agent is anchored at a user signaling server, and wherein said network includes one or more radio ports to enable wireless communication with said mobile station, further including means for updating said radio ports with a location of said user agent as said mobile station associated with said user agent moves.

22. The apparatus of claim 20, wherein said user agent is anchored at a user signaling server, and wherein said network includes one or more radio ports to enable wireless communication with said mobile station, wherein signaling links are established between said radio ports and a user signaling server in which said user agent is resident as said mobile station moves throughout said network.

28. The apparatus of claim 20, wherein said signalling functions further include call forwarding, mobile call termination status processing and compatibility checking of data transmissions.

23. A communications network including mobile stations within said network, wherein each of said mobile stations is associated with a cluster within said network, said network comprising:

a plurality of clusters;

at least one user signaling server associated with each said cluster of said network, wherein said user signaling server includes,

at least one user agent, said user agent being associated with an active individual mobile station, said user agent operable to mimic signaling functions of said associated mobile station and to negotiate, in behalf of said associated mobile station, signaling parameters in respect to a communications link to be established between said associated mobile station and one or more nodes in said communications network; and

means for effecting a migration of said user agent from a first signalling server to a target signaling server in a different cluster upon movement of said associated mobile station to said different cluster.

24. The network of claim 23, wherein each said cluster further includes:

at least one connection server for establishing a communication path in said cluster over which user voice and data information are transmitted;

at least one call server for maintaining the network state of a call within said cluster; and

further including at least one location server for tracking the location of a mobile station within said network.

25. The network of claim 24, wherein said mobile station is operable to generate a registration message to an associated location server upon changing clusters, wherein said location server signals to a target user signaling server to migrate said user agent associated with said mobile station, and wherein said target user signaling server is operable to request and receive relevant user agent parameters from a previous user signaling server.

26. The network of claim 23, wherein a previous user signaling server is operable to maintain a stub process in place of said user agent to buffer messages for said user agent during migration.

27. The network of claim 23, wherein said user agent operates a user process and said user process is operable to migrate by:

executing a new user process at a target user signaling server;

establishing a communications connection between a previous user process at a first user signaling server and said new user process;

transferring a data structure containing migration variables from said previous user process;

establishing communication channels at said new user process;

maintaining said previous user process as a stub process; and

forwarding messages received during migration to said new user process.

29. The network of claim 23, wherein said signalling functions further include call forwarding and mobile call termination status processing.