Methods and system for transferring calls within trunked digital radio communications systems

• US 6,317,595 B1
• Filed: 06/05/1998
• Issued: 11/13/2001
• Est. Priority Date: 06/05/1998
• Status: Expired due to Term

• Current Assignee: Eagle Technology, LLC (L3Harris Technologies, Inc.)
• Original Assignee: Com-Net Ericsson Critical Radio Systems, Inc. (TE Connectivity Limited)
• Inventors: St. John, James T., Janky, William O.
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): CRAVER, CHARLES R
• Application Number:
  US09/092,161
• Time in Patent Office: 1,257 Days
• Field of Search: 455/426, 455/417, 455/416, 455/450, 455/517, 455/524, 455/560, 455/561, 370/261, 370/263, 370/329, 370/335, 370/371, 370/458, 379/202, 379/208-214, 379/215, 379/372, 379/373
• US Class Current: 455/417
• CPC Class Codes: H04M 2203/2044 Group features, e.g. closed user group
• CPC Class Codes: H04M 2207/18 wireless networks
• CPC Class Codes: H04M 3/56 Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities video conference systems H04N7/15
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 76/20 Manipulation of established connections
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

Calls are transferred from a first call to a second call in a trunked digital radio communications system that includes a first transmitting user terminal that communicates with a receiving user terminal or group of user terminals in the first call over a first working channel via a base station. A second call is transmitted from a second transmitting user terminal to the base station over a second working channel, that identifies the receiving terminal. Transfer data is transmitted from the base station to the receiving terminal or group of user terminals in the first call on the first working channel, the transfer data identifying the second call and the second working channel. The transfer data is detected in the first call on the first working channel at the receiving user terminal and the receiving user terminal transfers to the second call on the second working channel based upon the transfer data.

Claims

1. A method of transferring from a first call to a second call within a trunked digital radio communications system that includes a first transmitting user terminal that communicates with a receiving user terminal in the first call over a first working channel via a base station, the method comprising the steps of:

transmitting from a second transmitting user terminal to the base station a second call over a second working channel, that identifies the receiving user terminal;

transmitting from the base station to the receiving user terminal transfer data in the first call on the first working channel, the transfer data identifying the second call and the second working channel;

detecting the transfer data in the first call on the first working channel at the receiving user terminal; and

transferring to the second call on the second working channel at the receiving user terminal based upon the transfer data, wherein the second working channel includes a second working channel downlink that links the base station to the receiving user terminal and wherein a current call is transmitted from the base station to the receiving user terminal on the second working channel downlink; and

transmitting verification data in the current call on the second working channel downlink that identifies the current call within the trunked digital radio communications system, said step of transmitting verification data comprising;

transmitting a frame number that identifies a control frame within the second working channel downlink;

transmitting a data type that identifies the current call as information data or as voice data;

transmitting a color code that identifies the current call within the trunked digital radio communications system; and

transmitting a call type identifier that identifies the current call as an encrypted call or an unencrypted call.

2. The method of claim 1, wherein said step of transmitting from the base station to the receiving user terminal transfer data in the first call on the first working channel comprises the steps of:

detecting the second call from the second transmitting user terminal on the second working channel;

generating transfer data on the first working channel that identifies the second call; and

transmitting the transfer data to the receiving user terminal within a control frame on a first working channel downlink that links the base station to the receiving user terminal on the first working channel.

3. The method of claim 2, wherein said step of transmitting the transfer data to the receiving user terminal within a control frame comprises the steps of:

transmitting a caller identification that identifies the receiving user terminal;

transmitting a channel assignment that identifies a second working channel downlink that links the base station to the receiving user terminal on the second working channel;

transmitting a time slot assignment that identifies the time slot within the second working channel downlink in which the second call is transmitted from the base station; and

transmitting a color code that identifies the second call within the trunked digital radio communications system.

4. The method of claim 1, wherein the first and second working channels are synchronized.

5. The method of claim 1, wherein said step of detecting the transfer data in the first call at the receiving user terminal comprises the steps of:

detecting a call identifier that identifies the receiving user terminal within the trunked digital radio communications system;

detecting a channel assignment that identifies a second working channel downlink that links the base station to the receiving user terminal on the second working channel;

detecting a time slot assignment that identifies a time slot within the second working channel in which the second call is transmitted from the base station; and

detecting a color code that identifies the second call within the trunked digital radio communications system.

6. The method of claim 1, wherein the second working channel includes a second working channel downlink that links the base station to the receiving user terminal and wherein the transfer data includes a time slot assignment;

and wherein said step of transferring to the second call comprises the steps of;

detecting that the second call from the second transmitting user terminal on the second working channel is a higher priority call than the first call to the receiving user terminal; and

receiving the second call transmitted by the base station on the second working channel downlink in the assigned time slot.

7. A method of transferring from a first call to a second call within a trunked digital radio communications system that includes a first transmitting user terminal that communicates with a receiving user terminal in the first call over a first working channel via a base station, the method comprising the steps of:

transmitting from a second transmitting user terminal to the base station a second call over a second working channel, that identifies the receiving user terminal;

transmitting from the base station to the receiving user terminal transfer data in the first call on the first working channel, the transfer data identifying the second call and the second working channel;

detecting the transfer data in the first call on the first working channel at the receiving user terminal;

transferring to the second call on the second working channel at the receiving user terminal based upon the transfer data, wherein the second working channel includes a second working channel downlink that links the base station to the receiving user terminal and wherein a current call is transmitted from the base station to the receiving user terminal on the second working channel downlink;

transmitting verification data in the current call on the second working channel downlink that identifies the current call within the trunked digital radio communications system, wherein the verification data in the current call includes a first color code that identifies the current call within the trunked digital radio communications system and wherein the transfer data in the first call includes a second color code that identifies the second call within the trunked digital radio communications system; and

comparing the first color code to the second color code.

8. The method of claim 7, further comprising the step of transferring to a control channel at the receiving user terminal when the first color code and the second color code are different.

9. A user terminal that communicates with a trunked digital radio communications system wherein the trunked digital radio communications system includes a base station linked to the user terminal by a first working channel and a second working channel, the user terminal comprising:

a transceiver that receives calls from the base station on the first and second working channels;

a detector, responsive to said transceiver, that detects transfer data within a first call on the first working channel; and

a switcher, responsive to said detector, that switches the transceiver to a second call on the second working channel based on the transfer data, wherein the second working channel includes a second working channel downlink that links the base station to the receiving user terminal and wherein a current call is transmitted from the base station to the receiving user terminal on the second working channel downlink; and

wherein said detector further detects verification data in the current call on the second working channel that identifies the current call within the trunked digital radio communications system said verification data comprising;

a frame number that identifies a control frame within the second working channel downlink;

a color code that identifies the current call within the trunked digital radio communications system; and

a call type identifier that identifies the current call as an encrypted call or an unencrypted call.

10. The user terminal of claim 9, wherein the transfer data within the first call comprises:

a caller identification that identifies the user terminal;

a channel assignment that identifies a second working channel downlink that links the base station to the user terminal on the second working channel;

a time slot assignment that identifies the time slot within the second working channel downlink in which the second call is transmitted from the base station; and

a color code that identifies the second call within the trunked digital radio communications system.

11. The user terminal of claim 10, wherein the detector detects the transfer data within the first call on the first working channel by detecting the call identifier that identifies the user terminal within the trunked digital radio communications system, detecting the channel assignment that identifies the second working channel downlink on which the second call is transmitted to the receiving user terminal, detecting the time slot assignment that identifies the time slot in the second working channel downlink in which the second call is transmitted from the base station to the receiving user terminal, and detecting the color code that identifies the second call in the trunked digital radio communications system.

12. The user terminal of claim 9, wherein the second working channel includes a second working channel downlink that links the base station to the receiving user terminal and wherein the second working channel downlink is identified in the transfer data in the first call and wherein the transfer data includes a time slot assignment;

and wherein said switcher receives the second call transmitted by the base station on the second working channel downlink in the assigned time slot.

13. A user terminal that communicates with a trunked digital radio communications system wherein the trunked digital radio communications system includes a base station linked to the user terminal by a first working channel and a second working channel, the user terminal comprising:

a transceiver that receives calls from the base station on the first and second working channels;

a detector, responsive to said transceiver, that detects transfer data within a first call on the first working channel; and

a switcher, responsive to said detector, that switches the transceiver to a second call on the second working channel based on the transfer data, wherein the second working channel includes a second working channel downlink that links the base station to the receiving user terminal and wherein a current call is transmitted from the base station to the receiving user terminal on the second working channel downlink; and

wherein said detector further detects verification data in the current call on the second working channel that identifies the current call within the trunked digital radio communications system and further wherein a first color code is included in the verification data that identifies the current call within the trunked digital radio communications system and wherein a second color code is included in the transfer data in the second call that identifies the second call within the trunked digital radio communications system; and

wherein said detector compares the first color code to the second color code.

14. The user terminal of claim 13, wherein said user terminal transfers to a control channel when the first color code and the second color code are different.

15. A base station within a trunked digital radio communications comprising:

a transceiver that relays a first call from a first transmitting user terminal to a receiving user terminal on a first working channel and receives a second call from a second transmitting user terminal on a second working channel; and

a processor, responsive to said transceiver, that places transfer data in the first call from the base station to the receiving user terminal on the first working channel, wherein the transfer data identifies the second call and the second working channel, wherein the second working channel includes a second working channel downlink that links the base station and the receiving user terminal, and wherein a current call is transmitted on the second working channel downlink; and

wherein said processor transmits verification data in the current call on the second working channel downlink that identifies the current call within the trunked digital radio communications system, said verification data comprising;

a frame number that identifies a control frame within the second working channel downlink;

a color code that identifies the current call within the trunked digital radio communications system; and

a call type identifier that identifies the current call as an encrypted call or an unencrypted call.

16. The base station of claim 15, wherein the first working channel includes a first working channel downlink that links the base station and the receiving user terminal and wherein the first working channel downlink includes a control frame;

and wherein said processor places the transfer data in the first call on the first working channel by detecting the second call from the second transmitting user terminal on the second working channel, generating the transfer data that identifies the second call, and placing the transfer data in the control frame in the first call on the first working channel downlink.

17. The base station of claim 15, wherein the transfer data within the first call comprises:

a caller identification that identifies the receiving user terminal;

a channel assignment that identifies a second working channel downlink that links the base station to the receiving user terminal on the second working channel;

a time slot assignment that identifies the time slot within the second working channel downlink in which the second call is transmitted from the base station; and

a color code that identifies the second call within the trunked digital radio communications system.

18. A system that transfers from a first call to a second call within a trunked digital radio communications system that includes a first transmitting user terminal that communicates with a receiving user terminal in the first call over a first working channel via a base station, the system comprising:

means for transmitting from a second transmitting user terminal to the base station a second call over a second working channel, that identifies the receiving user terminal;

means for transmitting from the base station to the receiving user terminal transfer data in the first call on the first working channel, the transfer data identifying the second call and the second working channel;

means for detecting the transfer data in the first call on the first working channel at the receiving user terminal; and

means for transferring to the second call on the second working channel at the receiving user terminal based upon the transfer data, wherein the second working channel includes a second working channel downlink that links the base station to the receiving user terminal and wherein a current call is transmitted from the base station to the receiving user terminal on the second working channel downlink, and wherein the system further comprises means for transmitting verification data in the current call on the second working channel downlink that identifies the current call within the trunked digital radio communications system, said means for transmitting verification data comprising;

means for transmitting a frame number that identifies a control frame within the second working channel downlink;

means for transmitting a data type that identifies the current call as information data or as voice data;

means for transmitting a color code that identifies the current call within the trunked digital radio communications system; and

means for transmitting a call type identifier that identifies the current call as an encrypted call or an unencrypted call.

19. The system of claim 18, wherein said means for transmitting from the base station to the receiving user terminal transfer data in the first call on the first working channel comprises:

means for detecting the second call from the second transmitting user terminal on the second working channel;

means for generating transfer data on the first working channel that identifies the second call; and

means for transmitting the transfer data to the receiving user terminal within a control frame on a first working channel downlink that links the base station to the receiving user terminal on the first working channel.

20. The system of claim 19, wherein said means for transmitting the transfer data to the receiving user terminal within a control frame comprises:

means for transmitting a caller identification that identifies the receiving user terminal;

means for transmitting a channel assignment that identifies a second working channel downlink that links the base station to the receiving user terminal on the second working channel;

means for transmitting a time slot assignment that identifies the time slot within the second working channel downlink in which the second call is transmitted from the base station; and

means for transmitting a color code that identifies the second call within the trunked digital radio communications system.

21. The system of claim 18, wherein the first and second working channels are synchronized.

22. The system of claim 18, wherein said means for detecting the transfer data in the first call at the receiving user terminal comprises:

means for detecting a call identifier that identifies the receiving user terminal within the trunked digital radio communications system;

means for detecting a channel assignment that identifies a second working channel downlink that links the base station to the receiving user terminal on the second working channel;

means for detecting a time slot assignment that identifies a time slot within the second working channel in which the second call is transmitted from the base station; and

means for detecting a color code that identifies the second call within the trunked digital radio communications system.

23. The system of claim 18, wherein the second working channel includes a second working channel downlink that links the base station to the receiving user terminal on the second working channel and wherein the transfer data includes a time slot assignment;

and wherein said means for transferring to the second call comprises;

means for detecting that the second call from the second transmitting user terminal on the second working channel is a higher priority call than the first call to the receiving user terminal;

means for receiving the second call transmitted by the base station on the second working channel downlink in the assigned time slot.

24. A system that transfers from a first call to a second call within a trunked digital radio communications system that includes a first transmitting user terminal that communicates with a receiving user terminal in the first call over a first working channel via a base station, the system comprising:

means for transmitting from a second transmitting user terminal to the base station a second call over a second working channel, that identifies the receiving user terminal;

means for transmitting from the base station to the receiving user terminal transfer data in the first call on the first working channel, the transfer data identifying the second call and the second working channel;

means for detecting the transfer data in the first call on the first working channel at the receiving user terminal; and

means for transferring to the second call on the second working channel at the receiving user terminal based upon the transfer data, wherein the second working channel includes a second working channel downlink that links the base station to the receiving user terminal and wherein a current call is transmitted from the base station to the receiving user terminal on the second working channel downlink, and wherein the system further comprises means for transmitting verification data in the current call on the second working channel downlink that identifies the current call within the trunked digital radio communications system, wherein the verification data in the current call includes a first color code that identifies the current call in the trunked digital radio communications system and wherein the transfer data in the first call includes a second color code that identifies the second call in the trunked digital radio communications system; and

wherein the system further comprises means for comparing the first color code to the second color code.

25. The system of claim 24, further comprising means for transferring to a control channel at the receiving user terminal when the first color code and the second color code are different.