Full duplex direct mode individual and group calling using adjacent time slots in a TDMA system

• US 9,232,522 B2
• Filed: 07/19/2013
• Issued: 01/05/2016
• Est. Priority Date: 07/19/2013
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola Solutions, Inc.
• Inventors: Khoo, Hun Weng, Chung, Yueh Ching, Wiatrowski, David G, Bohn, Thomas B
• Primary Examiner(s): YEUNG, MANG HANG
• Application Number:
  US13/946,464
• Publication Number:
  US 20150023227A1
• Time in Patent Office: 900 Days
• Field of Search: 370272-297, 370/345, 455/73
• US Class Current: 1/1
• CPC Class Codes: H04B 7/2656 for structure of frame, burst
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

A method for enabling full duplex direct mode calls between radios in an N:1 slotting ratio TDMA radio system includes detecting a request for a full duplex direct mode call at a first radio, transmitting in a particular slot of a first recurring time slot of N recurring time slots on a first single frequency one of a call request and a call header identifying the call as a full duplex call. Subsequently transmitting, by the first radio, during a plurality of subsequent first recurring time slots, outbound voice and/or data transmissions. And receiving, during a plurality of second recurring time slots of the N recurring time slots, each second recurring timeslot positioned immediately adjacent a respective first recurring time slot in an interleaved manner, inbound voice and/or data transmissions from the second radio and playing back the inbound voice and/or data transmission at the first radio.

Claims

1. A method for enabling full duplex calls in a direct mode between radios in an N:

1 slotting ratio time division multiple access (TDMA) radio system, the method comprising;

detecting, at a first radio, a request for a full duplex direct mode call from the first radio to at least a second radio;

wirelessly transmitting, in a particular slot of a first recurring time slot of N recurring time slots on a first single frequency, one of a call request and a call header identifying the call as a full duplex call;

wirelessly transmitting, by the first radio, during a plurality of subsequent first recurring time slots, outbound voice and/or data transmissions; and

wirelessly receiving, at the first radio, during a plurality of second recurring time slots of the N recurring time slots on the first single frequency, each second recurring timeslot positioned immediately adjacent a respective first recurring time slot in an interleaved manner, inbound voice and/or data transmissions from the second radio and playing back the inbound voice and/or data transmission at the first radio; and

wherein the direct mode of the full duplex direct mode call is a mode of operation where the first and second radios communicate directly with each other using the first single frequency without the use of any or all external infrastructure equipment.

2. The method of claim 1, further comprising determining, by the first radio and prior to transmitting the call request, that the first and second recurring timeslots are available on the first single frequency for the full duplex call.

3. The method of claim 1, wherein:

the full duplex call request is an individual call;

the step of transmitting comprises repeatedly transmitting the call request in first recurring time slots until a response is received from the second radio acknowledging the request, so as to reserve both the first and second recurring time slots until the response is received;

and wherein the response is received from the second radio during the second recurring time slot prior to receiving the inbound voice and/or data transmissions during the second recurring time slot.

4. The method of claim 1, wherein the one of the call request and the call header explicitly identifies the first and second recurring time slots via a one or more bit settings within the one of the call request and the call header.

5. The method of claim 1, wherein the one of the call request and the call header implicitly identifies the first and second recurring time slots based solely on its transmission on the first recurring time slot.

6. The method of claim 1, wherein the request indicates that it is a full duplex group call and the step of wirelessly transmitting one of a call request and a call header comprises broadcasting the call header, the call header including a group identifier identifying a target group for the full duplex group call.

7. The method of claim 6, further comprising responsive to determining to terminate the first radio'"'"'s transmission in the full duplex group call:

transmitting, by the first radio, a termination message during a second particular slot of the first recurring time slot indicating the first radio'"'"'s transition to an inactive status;

subsequently receiving, in the first recurring time slot, second inbound voice and/or data transmissions from a third radio; and

combining and simultaneously playing back the first inbound voice and/or data transmissions from the second radio and the second inbound voice and/or data transmission from the third radio.

8. The method of claim 7, further comprising, responsive to detecting, at the first radio, a second request to transmit in the full duplex direct mode call:

detecting whether one of the first recurring time slot and the second recurring time slot is available to transmit in; and

responsive to detecting active transmissions in the first and second recurring time slots, denying the second request.

9. The method of claim 7, wherein the request is a full duplex direct mode group call request, the method further comprising, responsive to detecting, at the first radio, a second request to transmit in the full duplex direct mode call:

detecting whether one of the first recurring time slot and the second recurring time slot is available to transmit in; and

responsive to failing to detect any active transmissions in the second recurring time slot;

wirelessly transmitting, by the first radio, during the second recurring time slot, second outbound voice and/or data transmissions; and

wirelessly receiving, at the first radio, during the first recurring time slot, second inbound voice and/or data transmissions from the third radio and playing back the second inbound voice and/or data transmission at the first radio.

10. The method of claim 1, wherein N is 2.

11. The method of claim 1, further comprising:

wirelessly receiving, at the first radio, during a particular one of a third recurring time slot of the N recurring time slots, each third recurring timeslot positioned immediately adjacent the second recurring time slot and the first recurring timeslot in an interleaved manner, second inbound voice and/or data transmissions from a third radio; and

combining and simultaneously playing back the first inbound voice and/or data transmissions from the second radio and the second inbound voice and/or data transmission from the third radio.

12. The method of claim 1, further comprising receiving a transmit interrupt message during the second recurring time slot, determining, by the contents of the interrupt message, whether the transmit interrupt message requests tear down of only the second recurring time slot or the entire full duplex call, and responsive to determining that the transmit interrupt message requests tear down of the entire full duplex call, refraining from further transmitting during the first recurring time slot and ending the call.

13. The method of claim 1, wherein detecting, at a first radio, a request for a full duplex direct mode call from the first radio to at least a second radio, further comprises:

detecting push-to-talk (PTT) button press at the first radio.

14. A radio capable of communicating in a full duplex call in a direct mode between one or more other radios in an N:

1 slotting ratio time division multiple access (TDMA) radio system, the radio comprising;

a transceiver;

a memory; and

a processor configured to;

detect a request for a full duplex direct mode call from the radio to at least a second radio;

wirelessly transmit, via the transceiver, in a particular slot of a first recurring time slot of N recurring time slots on a first single frequency, one of a call request and a call header identifying the call as a full duplex call;

wirelessly transmit, via the transceiver, during a plurality of subsequent first recurring time slots, outbound voice and/or data transmissions;

wirelessly receive, via the transceiver, during a plurality of second recurring time slots of the N recurring time slots of the first single frequency, each second recurring timeslot positioned immediately adjacent a respective first recurring time slot in an interleaved manner, inbound voice and/or data transmissions from the second radio; and

play back the inbound voice and/or data transmission; and

wherein the direct mode of the full duplex direct mode call is a mode of operation where the first and second radios communicate directly with each other using the first single frequency and without the use of any or all external infrastructure equipment.

15. The radio of claim 14, wherein the processor is further configured to determine, via the transceiver and prior to transmitting the call request, that the first and second recurring timeslots are available on the first single frequency for the full duplex call.

16. The radio of claim 14, wherein:

the full duplex call request is an individual call;

the processor is further configured to repeatedly transmit the call request, via the transceiver, in first recurring time slots until a response is received from the second radio acknowledging the request, so as to reserve both the first and second recurring time slots until the response is received;

and the processor is further configured to receive, via the transceiver and from the second radio, the response during the second recurring time slot prior to receiving the inbound voice and/or data transmissions during the second recurring time slot.

17. The radio of claim 14, wherein the one of the call request and the call header explicitly identifies the first and second recurring time slots via a one or more bit settings within the one of the call request and the call header.

18. The radio of claim 14, wherein the one of the call request and the call header implicitly identifies the first and second recurring time slots based solely on its transmission on the first recurring time slot.

19. The radio of claim 14, wherein the request indicates that it is a full duplex group call and the processor is further configured to broadcast, via the transceiver, the call header, the call header including a group identifier identifying a target group for the full duplex group call.

20. The radio of claim 14, wherein N is 2.

21. The radio of claim 14, wherein the processor is further configured to receive, via the transceiver, a transmit interrupt message during the second recurring time slot, and responsively determine, by the contents of the interrupt message, whether the transmit interrupt message requests tear down of only the second recurring time slot or the entire full duplex call, and responsive to determining that the transmit interrupt message requests tear down of the entire full duplex call, refraining from further transmitting during the first recurring time slot and ending the call.