Radio communications system and method for mobile assisted handover between a private network and a public mobile network

• US 6,112,088 A
• Filed: 08/30/1996
• Issued: 08/29/2000
• Est. Priority Date: 08/30/1996
• Status: Expired due to Term

• Current Assignee: Optis Cellular Technology LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Haartsen, Jacobus Cornelis
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US08/708,034
• Time in Patent Office: 1,460 Days
• Field of Search: 455/437, 455/440, 455/442, 455/443, 455/445, 455/444, 455/436, 455/502, 455/525, 455/552, 455/554, 455/555, 370/330, 370/331, 370/332, 370/333, 370/336, 370/337
• US Class Current: 455/437
• CPC Class Codes: H04W 36/0066 of control information between different types of networks in order to establish a new radio link in the target network
• CPC Class Codes: H04W 84/105 PBS [Private Base Station] network H04W84/12 - H04W84/16 take precedence

Abstract

Mobile handover between a private radio communications network connected to the public switch telephone network and a public land mobile network also connected to the public switch telephone network are provided by a radio communications mobile terminal supporting simultaneous communication connections between the two uncoordinated networks. The mobile terminal monitors a base station of the public land mobile network during idle frames of communication connections with the private radio communications network, thereby synchronizing the mobile terminal to both the base of the public land mobile network and the private radio communications network. Call interruption is prevented during handover by maintaining simultaneous communications with the private radio communications network and the public land mobile network through the use of two half-rate channels or dual-slot communications where both the public land mobile network and private radio communications network operate pursuant to compatible TDMA standards. Handover is initiated when the mobile terminal detects a signal quality which violates a predetermined switching criteria and passes the PSTN phone line number of the private radio communications network to the base station of the public land mqbile network which in turn requests re-routing of the call from the PSTN switch.

Claims

1. A method for mobile assisted handover between a TDMA private radio communications network connected to a wire line switch and having a wire line number and a TDMA public land mobile network, of a first communication connection between a mobile terminal and the wire line switch including a first radio communication connection between the mobile terminal and the private radio communications network, said method comprising the steps of:

monitoring a base station of the public land mobile network having a frame timing at the mobile terminal and synchronizing a frame timing of the mobile terminal to the frame timing of the base station of the public land mobile network;

establishing the first radio communication connection between the mobile terminal and a base station of the private radio communications network using the frame timing of the mobile terminal, the base station of the private radio communications network having a frame timing uncoordinated with the frame timing of the base station of the public land mobile network in that common shared frame timing is not provided between the private radio communications network and the public land mobile network;

detecting a signal quality of the first radio communication connection from the private radio communications network at the mobile terminal;

establishing a second radio communication connection between the mobile terminal and the public land mobile network simultaneously with the first radio communication connection if the detected signal quality has violated a predetermined switching criteria;

reporting the wire line number of the private radio communications network to the public land mobile network over the second radio communication connection; and

, initiating rerouting of the first communication connection from the wire line switch to the public land mobile network.

2. The method of claim 1 wherein said initiating step is followed by the step of accepting the rerouted first communication connection from the public land mobile network.

3. The method of claim 2 wherein said accepting step is followed by the step of disconnecting the first radio communication connection between the mobile terminal and the private radio communications network.

4. The method of claim 1 wherein said establishing step includes the step of synchronizing communications timing between the base station of the public land mobile network and the base station of the private radio communications network.

5. The method of claim 1 wherein the mobile terminal is a dual-slot mobile phone and wherein said establishing step includes the step of allocating a first slot to the first radio communication connection and a second slot to the second radio communication connection.

6. The method of claim 1 wherein said establishing step includes the step of allocating a first half rate channel to the first radio communication connection and a second half rate channel to the second radio communication connection.

7. The method of claim 1 wherein said step of monitoring a base station of the public land mobile network includes the step of synchronizing the mobile terminal to the monitored base station of the public land mobile network while the first communications connection is routed to the mobile terminal over the private radio communications network.

8. The method of claim 7 wherein said monitoring step is performed by the mobile terminal during idle frames.

9. The method of claim 1 wherein said detecting step includes the step of determining a received signal strength indication for the first radio communication connection between the mobile terminal and the private radio communications network.

10. The method of claim 9 wherein said detecting step further includes the step of determining a bit error rate for the first radio communication connection between the mobile terminal and the private radio communications network.

11. The method of claim 1 wherein said reporting step includes the step of obtaining the wire line number from the private radio communications network over a radio communication control channel between the mobile terminal and the private radio communications network.

12. A method for mobile assisted handover between a private radio communications network connected to a wire line switch and having a wire line number and a public land mobile network of a first communication connection between the mobile terminal and the wire line switch including a first radio communication connection between the mobile terminal and the private radio communications network, said method comprising the steps of:

monitoring a base station of the public land mobile network at the mobile terminal and synchronizing the mobile terminal to the base station of the public land mobile network;

establishing the first radio communication connection between the mobile terminal and a base station of the private radio communications network which is not coordinated with the base station of the public land mobile network, in that common shared frame timing is not provided between the private radio communications network and the public land mobile network, by synchronizing the base station of the private radio communications network to the mobile terminal;

detecting a signal quality of the first radio communication connection from the private radio communications network at the mobile terminal;

establishing a second radio communication connection between the mobile terminal and the public land mobile network simultaneously with the first radio communication connection if the detected signal quality has violated a predetermined switching criteria; and

reporting the wire line number of the private radio communications network to the public land mobile network over the second radio communication connection.

13. The method of claim 12 wherein said reporting step is followed by the steps of:

accepting the rerouted first communication connection from the public land mobile network; and

disconnecting the first radio communication connection between the mobile terminal and the private radio communications network.

14. The method of claim 13 wherein the public land mobile network and the private radio communications network are both TDMA systems.

15. The method of claim 14 wherein said step of monitoring a base station of the public land mobile network includes the step of synchronizing the mobile terminal to the monitored base station of the public land mobile network while the first communications connection is routed to the mobile terminal over the private radio communications network.

16. A radio communications mobile terminal for use with a private radio communications network connected to a wire line switch and having a wire line number located within a public land mobile network, comprising:

means for monitoring a base station of the public land mobile network at the mobile terminal and synchronizing the mobile terminal to the base station of the public land mobile network;

means for establishing a first radio communication connection between the mobile terminal and a base station of the private radio communications network which is not coordinated with the base station of the public land mobile network, in that common shared frame timing is not provided between the private radio communications network and the public land mobile network by synchronizing the base station of the private radio communications network to the mobile terminal;

detecting means for detecting a signal quality from said private radio communications network during the first radio communication connection between said mobile terminal and said private radio communications network;

simultaneous communication establishing means responsive to said detecting means for establishing a second radio communication connection between said mobile terminal and said public land mobile network simultaneously with said first radio communication connection if said detected signal quality has violated a stored switching criteria; and

,

wire line reporting means for reporting said stored wire line number to said public land mobile network over said second radio communication connection.

17. The mobile terminal of claim 16 wherein the public land mobile network and the private radio communications network are both TDMA systems.

18. The mobile terminal of claim 17 wherein said monitoring means includes means for monitoring the base station of said public land mobile network during idle frames.

19. The mobile terminal of claim 17 wherein said simultaneous communication establishing means includes means for allocating a first slot to the first radio communication connection and a second slot to the second radio communication connection.

20. The mobile terminal of claim 17 wherein said simultaneous communication establishing means includes means for allocating a first half rate channel to the first radio communication connection and a second half rate channel to the second radio communication connection.

21. A radio communications mobile terminal for use with a TDMA private radio communications network connected to a wire line switch and having a wire line number located within a TDMA public land mobile network, comprising:

radio transceiving means for receiving and transmitting radio communications signals between said mobile terminal and said private radio communications network and between said mobile terminal and said public land mobile network, wherein the private radio communications network is not coordinated with the public land mobile network in that common shared frame timing is not provided between the private radio communications network and the public land mobile network;

detecting means operably connected to said radio transceiving means for detecting a signal quality from said private radio communications network during a first radio communication connection between said mobile terminal and said private radio communications network;

comparing means operably connected to said detecting means for comparing said detected signal quality to a predetermined switching criteria;

simultaneous communication establishing means and electrically connected to said transceiving means and responsive to said comparing means for establishing a second radio communication connection between said mobile terminal and said public land mobile network simultaneously with said first radio communication connection if said detected signal quality has violated said predetermined switching criteria, said simultaneous communication establishing means including synchronizing means operably connected to said radio transceiving means for synchronizing radio communications between said mobile terminal and said private radio communications network and said public land mobile network so as to provide a common frame timing for all simultaneous radio communications; and

,

reporting means for reporting said wire line number to said public land mobile network and requesting rerouting of said first radio communication connection from said private radio communications network to said public land mobile network over said second radio communication connection.

22. The mobile terminal of claim 21 wherein said synchronizing means includes means for monitoring said public land mobile network during idle frames and wherein said wire line switch is a PSTN switch and said wire line number is a PSTN number.

23. The mobile terminal of claim 21 wherein said simultaneous communication establishing means includes means for allocating a first slot to the first radio communication connection and a second slot to the second radio communication connection.

24. The mobile terminal of claim 21 wherein said simultaneous communication establishing means includes means for allocating a first half rate channel to the first radio communication connection and a second half rate channel to the second radio communication connection.