In-call DTMF transport for geostationary mobile satellite communication system

US6650895B1 · kind B1 · utility

Assignee

• HUGHES ELECTRONICS LIMITED · US

Inventors

• Channasandra Ravishankar · Clarksburg, US
• David Roos · Centreville, US
• Anthony Noerpel · Lovettsville, US
• Chandra Joshi · Saratoga, US
• James Hobza · Carlsbad, US
• Prabir Datta · Langen, DE
• Yi-Shen Chen · Wang'an Town, TW

Key dates

• Filing date: Nov 23, 1999
• Grant date: Nov 18, 2003
• Expiry date: Nov 23, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04Q1/45
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

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 A…