Push-to-talk group call system using CDMA 1x-EVDO cellular network

• US 20070049314A1
• Filed: 08/30/2005
• Published: 03/01/2007
• Est. Priority Date: 08/30/2005
• Status: Active Grant

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Balachandran, Krishna, Kang, Joseph, Budka, Kenneth
• Granted Patent: US 7,970,425 B2
• Time in Patent Office: Days
• US Class Current: 455/518
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 52/10 Open loop power control
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services

Abstract

A push-to-talk (“PTT”) group call system, for use as, e.g., a public safety wireless network, includes a CDMA-based 1x-EVDO radio access network operably connected to a PTT server over an IP network. The radio access network includes base stations for radio communications with a number of distributed mobile stations. In carrying out wireless communications, the group call system combines IP-based voice and other real-time multimedia services with the 1x-EVDO radio access network'"'"'s Broadcast Multicast Service. This allows a number of users to receive the same copy of an IP-based media stream for point-to-multipoint, group transmissions. To reduce call setup times, the group call system uses “standing” call groups, which are ongoing group communication channels pre-established between the PTT server and authorized group users. Thus, mobile stations link to one or more standing call groups of interest upon power-up, prior to users speaking.

Claims

1. A method of communicating with a plurality of wireless access terminals over a wireless network, the method comprising the steps of:

assigning a floor to a first of said access terminals based on a message received from at least one of said access terminals; and

transmitting at least one of a broadcast flow and a multicast flow to the access terminals other than the first access terminal, said flow comprising data received from the first access terminal.

2. The method of claim 1 further comprising:

the at least one broadcast flow and multicast flow comprises a BCMCS flow;

transmitting unicast data in BCMCS slots to at least one of the access terminals; and

scheduling the BCMCS slots for the unicast data if no data is transmitted as the BCMCS flow.

3. The method of claim 1 further comprising the step of:

transmitting parameters to the access terminals for commonly accessing the at least one broadcast flow and multicast flow.

4. The method of claim 3 wherein:

the parameters are transmitted as one or more broadcast overhead messages sent at a fastest allowable rate of the network.

5. The method of claim 1 further comprising the step of:

registering the access terminals for a call group.

6. The method of claim 5 further comprising the step of:

scheduling the at least one broadcast flow and multicast flow, wherein said flow is scheduled only in sectors where at least one access terminal has registered for the call group.

7. The method of claim 5 further comprising the steps of:

authenticating the access terminals; and

transmitting parameters to the authenticated access terminals for commonly accessing the broadcast or multicast flow, wherein the call group is a standing call group comprising the plurality of authenticated access terminals each provided with the parameters for accessing the broadcast or multicast flow, and wherein the parameters are transmitted independent and in advance of the time the message is received for use in assigning the floor.

8. The method of claim 1 further comprising the step of:

transmitting at least one communication signaling message to one or more of the access terminals as at least one of a broadcast flow and a multicast flow.

9. The method of claim 1 wherein:

communication resource allocations for the at least one broadcast flow and multicast flow are maintained during periods when no data is being transmitted as the BCMCS flow.

10. The method of claim 1 further comprising the step of, prior to the step of transmitting data received from the first access terminal the other access terminals:

transmitting at least one control message indicating that the data is being transmitted as the at least one broadcast flow and multicast flow.

11. A method of communicating over a wireless network comprising the steps of:

registering with the network for a standing call group comprising a plurality of access terminals each provided with parameters for accessing at least one of a broadcast flow and a multicast flow; and

accessing the at least one of the broadcast flow and multicast flow based on the parameters, wherein the at least one of the broadcast flow and multicast flow comprises data from one of said plurality of access terminals.

12. The method of claim 11 further comprising the steps of:

monitoring the at least one of the broadcast flow and multicast flow while in a unicast sleep mode.

13. The method of claim 11 further comprising the step of:

transmitting an initial access probe to the network, wherein a power level of the initial access probe is selected from the group consisting of;

a maximum access probe transmit power; and

a power level greater than a power level calculated according to an open loop power estimate of the network.

14. The method of claim 11 further comprising the steps of:

transmitting an access probe to the network upon passage of a persistence test; and

setting a parameter of the persistence test so that a delay of the access probe transmission is minimized and/or at a lower level than an access probe delay associated with access terminals that have less stringent delay requirements.

15. The method of claim 11 further comprising the steps of:

transmitting a floor request message to the network upon actuation of a pressel; and

transmitting the data to the network upon receipt of a floor assignment message, wherein the floor assignment message is received over a broadcast or multicast flow.

16. The method of claim 11 wherein:

the at least one of the broadcast flow and multicast flow comprises at least one BCMCS flow having a BCMCS bearer flow and an associated BCMCS signaling flow, each having an associated BCMCS program identifier.

17. The method of claim 11 further comprising the step of:

decoding broadcast overhead messages containing information about the at least one of the broadcast flow and multicast flow.

18. A method of communicating with a plurality of wireless access terminals over a wireless network, the method comprising the steps of:

transmitting parameters to the access terminals for commonly accessing at least one of a broadcast flow and a multicast flow;

granting a floor to the first access terminal based on a message from a first of said access terminals; and

transmitting data received from the first access terminal to the other access terminals over the at least one of the broadcast flow and multicast flow.

19. The method of claim 18 further comprising:

the at least one of the broadcast flow and the multicast flow comprises a BCMCS flow;

transmitting unicast data in BCMCS slots to at least one of the access terminals; and

scheduling the BCMCS slots for the unicast data if no data is transmitted as the BCMCS flow.

20. The method of claim 18 wherein:

communication resource allocations for the at least one of the broadcast flow and multicast flow are maintained during periods when no data is being transmitted as the broadcast or multicast flow.