Reduced latency in half-duplex wireless communications

• US 20040224678A1
• Filed: 05/08/2003
• Published: 11/11/2004
• Est. Priority Date: 05/08/2003
• Status: Abandoned Application

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Starent Networks Corporation (Cisco Systems, Inc.)
• Inventors: Dahod, Ashraf M., Silva, Michael
• Application Number:
  US10/431,818
• Publication Number:
  US 20040224678A1
• Time in Patent Office: Days
• US Class Current: 455/426.1
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation

Abstract

A system and method for reducing the latency or apparent latency of half-duplex (e.g. push-to-talk “PTT” wireless communications, including storing a voice message or a portion thereof while establishing a real-time half-duplex communication session to minimize the initial wait time experienced by the PTT session originator.

Claims

1. A method for reducing apparent latency in a half-duplex wireless communication system, comprising:

receiving a request signal from a first wireless device indicating that a half-duplex communication link is to be established with a second wireless device;

returning a response signal to the first wireless device indicating that the system is ready to accept a half-duplex voice signal from the first wireless device;

receiving the half-duplex voice signal from the first wireless device;

electronically storing the half-duplex voice signal;

sending the half-duplex voice signal to the second wireless device; and

establishing a real-time half-duplex communication link between the first and second wireless devices.

2. The method of claim 1, wherein the response signal is returned prior to establishing the real-time communication link between the first and second wireless devices.

3. The method of claim 1, wherein the half-duplex wireless communication is push-to-talk (PTT) communication.

4. The method of claim 1, further comprising encoding the received half-duplex voice signal as a digital audio file prior to storing the signal.

5. The method of claim 1, further comprising decoding the stored signal prior to sending the signal to the second wireless device.

6. The method of claim 1, wherein the half-duplex communication takes place over a cellular communication channel.

7. The method of claim 1, wherein the half-duplex communication is packet-switched voice over Internet protocol (VoIP).

8. The method of claim 1, wherein the apparent latency is less than the time required to establish the real-time communication link between the first and the second wireless devices.

9. The method of claim 1, wherein the half-duplex communication link also includes a third wireless device.

10. A system for providing a half-duplex communication session between a first wireless device and a second wireless device, comprising:

a full-duplex communication network, coupled to the first and second wireless devices, that carries voice communication signals between the first and second wireless devices;

an encoder, coupled to the communication network, that receives a half-duplex voice signal from the first wireless device and generates an encoded audio file corresponding to the half-duplex voice signal;

a storage device coupled to the encoder that stores the encoded audio file;

a decoder, coupled to the storage device, that decodes the stored audio file and generates a corresponding playback signal; and

a controller that controls the half-duplex communication session, including establishing a connection to the second wireless device, delivering the playback signal to the second wireless device, and establishing a real-time half-duplex communication link between the first and second wireless devices.

11. The system of claim 10, wherein any of the first and second wireless devices comprise a cellular telephone.

12. The system of claim 10, wherein the half-duplex communication session is a push-to-talk (PTT) session.

13. The system of claim 10, wherein the controller comprises an Internet media gateway (IMG).

14. The system of claim 10, wherein the communication network comprises any of:

a telephone network, a broadband network and an Internet connection.

15. The system of claim 10, further comprising the first wireless device, wherein the first wireless device includes a memory and a processor that executes instructions stored in the memory.

16. A method for reducing apparent latency in a half-duplex wireless communication system, comprising:

receiving a request signal from a first wireless device indicating that a push-to-talk (PTT) communication link is to be established with a second wireless device;

returning a response signal to the first wireless device indicating that the system is ready to accept a PTT voice signal from the first wireless device;

receiving the PTT voice signal from the first wireless device;

encoding the received voice signal as a digital audio file;

electronically storing the digital audio file;

establishing a communication link with the second wireless device;

decoding the stored digital audio file;

sending the decoded digital audio file to the second wireless device; and

establishing a real-time half-duplex communication link between the first and second wireless devices.

17. A system for providing a half-duplex communication session between a first wireless device and a second wireless device, comprising:

means for full-duplex communication, coupled to the first and second wireless devices, that carries voice communication signals between the first and second wireless devices;

means for encoding the voice communication signals, coupled to the communication network, that receives a half-duplex voice signal from the first wireless device and generates an encoded audio file corresponding to the half-duplex voice signal;

means for storing the encoded audio file, coupled to the encoding means;

means for decoding the stored audio file, coupled to the storage means, that decodes the stored audio file and generates a corresponding playback signal; and

means for controlling the half-duplex communication session, including establishing a connection to the second wireless device, delivering the playback signal to the second wireless device, and establishing a real-time half-duplex communication link between the first and second wireless devices.

18. A method for reducing apparent latency in a half-duplex communication session over a full-duplex communication system infrastructure, the method comprising dividing a total latency in establishing a real-time half-duplex communication session into at least two parts:

a first part substantially comprising a time period from the time a request for the half-duplex session is made until a confirmation response is provided to a maker of the request; and

a second part substantially comprising a time period from the time when the confirmation response is provided to the maker of the request until the time at which the real-time half-duplex communication session is established.

19. The method of claim 18, further comprising receiving a half-duplex voice signal from the maker of the request following the first part.

20. The method of claim 19, further comprising storing the half-duplex voice signal in a storage device.

21. The method of claim 20, further comprising delivering the stored signal to a recipient prior to establishing the real-time half-duplex communication session.