In-call DTMF transport for geostationary mobile satellite communication system

• US 6,650,895 B1
• Filed: 11/23/1999
• Issued: 11/18/2003
• Est. Priority Date: 11/24/1998
• Status: Expired due to Term

• Current Assignee: Hughes Network Systems LLC (Echostar Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Chen, Yi, Roos, David, Hobza, James, Noerpel, Anthony, Ravishankar, Channasandra, Datta, Prabir, Joshi, Chandra
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): RAMPURIA, SHARAD K
• Application Number:
  US09/447,696
• Time in Patent Office: 1,456 Days
• Field of Search: 455/560, 455/564, 455/427, 455/422.1, 379/355.01, 379/355.03, 379/357.03, 379/230, 379/221.08, 379/283, 370/467, 370/469
• US Class Current: 455/422.1
• CPC Class Codes: H04B 7/19 Earth-synchronous stations
• CPC Class Codes: H04M 3/2281 Call monitoring, e.g. for law enforcement purposes; Call tracing; Detection or prevention of malicious calls
• CPC Class Codes: H04M 3/533 Voice mail systems
• CPC Class Codes: H04Q 1/45 using multi-frequency signalling H04Q1/46 takes precedence

Abstract

A system and a methodology to improve the end-user quality of service both in terms of response time and reliability for the transport of in-call DTMF signals in wireless systems, particularly in geostationary mobile satellite systems. The methodology encompasses several techniques to provide acceptable end-to-end quality of service for DTMF. A technique is applicable for transport of DTMF in the wireless subscriber to network direction, where DTMF digits are carried in the form of an out-band message. The central part of the technique is to allow multiple key presses in the same message, thereby increasing efficiency and throughput in long-delay environment. Another technique utilizes the vocoder'"'"'s functionality to carry DTMF in-band, thereby reducing system complexity. The scheme makes the use of an integrated DTMF detector which can classify a given frame of signal into several classes so that the DTMF encoded packet can carry a unique pattern across the air-interface to the voice decoder at AT, which is capable of identifying the pattern. Another technique pertains to the use of a message based DTMF transport between two-ATs on a separate logical channel with a unique Service Access point Identifier (SAPI) providing guaranteed service for DTMF transport in an AT-AT call.

Claims

1. A system for in-call DTMF transport in long delay environments, comprising:

an access terminal (AT) for coupling a dual tone multi-frequency (DTMF) transmission application to a wireless network, the AT comprising;

a DTMF presentation sublayer allowing application specific generation of DTMF signals;

a radio resource management layer coupled to said DTMF presentation sublayer for receiving AT DTMF signals;

said radio resource management layer converting DTMF digits to out-band messages;

a network communication link for receiving said out-band messages from said radio resource management layer for communicating the DTMF signals as out-band messages.

2. A system as recited in claim 1 wherein said radio resource management layer converts multiple DTMF key signals to a reduced set of out-band messages.

3. A system as recited in claim 2 wherein said radio resource management layer converts multiple DTMF signals to a single out-band message for transmission over the wireless network.

4. A system as recited in claim 3 wherein said radio resource management layer converts the DTMF signals into packet data for transmission over the wireless network.

5. A system for in-band message transport in long delay environments, comprising:

a voice encoder in gateway having an integrated DTMF detector that detects DTMF signal and encodes into a packet with a special pattern; and

a voice decoder coupled to said radio resource management layer for coding the DTMF signals as in-band signals coupled directly to a wireless network.

6. A system as recited in claim 5 wherein said vocoder is provided as an integrated DTMF detector which classifies data frames into DTMF encoded packets for transmission of unique data patterns across the wireless network via the vocoder at the AT.

7. A system as recited in claim 6 wherein said AT identifies the data patterns responding to the DTMF message signal encoded packets.

8. A system as recited in claim 5 wherein said radio resource management layer converts the DTMF signals into packet data for transmission over the wireless network.

9. A system for in-call signaling transport in long delay environments, comprising:

an access terminal (AT) for coupling a dual tone multi-frequency (DTMF) transmission application to a wireless network, the AT comprising;

a DTMF presentation sublayer allowing application specific generation of DTMF signals;

a radio resource management layer coupled to said DTMF presentation sublayer for receiving AT DTMF signals;

a network communication link for receiving out-band messages from said radio resource management layer for communicating the DTMF signals; and

a communications channel for use by said AT providing a unique service access point identifier (SAPI) for DTMF message signal transport.

10. A system as recited in claim 9 wherein said radio resource management layer converts the DTMF signals into out-band messages for transmission over the wireless network.

11. A system as recited in claim 9 comprising a second AT in communication with said first AT under the control of a gateway station subsystem, wherein the separate channel provides in-call signaling between said first and second ATs during communications therebetween.