Browse Prior Art Database

METHOD FOR COORDINATED SIMULTANEOUS TRANSMISSION OF VOICE AND DATA USING MOBILE CHANNELS

IP.com Disclosure Number: IPCOM000008662D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-02
Document File: 4 page(s) / 168K

Publishing Venue

Motorola

Related People

Gregory Cox: AUTHOR [+3]

Abstract

Many wireless applications could be enabled or enhanced by providing simultaneous voice and data through wireless mobile communications systems such as iDEN (Motorola's integrated Digital Enhanced Network) or GSM. Limited bandwidth, the need to minimize subscriber cost, and the requirement for maintaining voice quality conspire against simultaneous voice and data.

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MOTOROLA Technical Drvelopments

METHOD FOR COORDINATED SIMULTANEOUS TRANSMISSION OF VOICE AND DATA USING MOBILE CHANNELS

by Gregory Cox, Mark Gannon and Steve Emeott

BACKGROUND

  Many wireless applications could be enabled or enhanced by providing simultaneous voice and data through wireless mobile communications systems such as iDEN (Motorola's integrated Digital Enhanced Network) or GSM. Limited bandwidth, the need to minimize subscriber cost, and the requirement for maintaining voice quality conspire against simultaneous voice and data.

  Voice Activity Detection is a known technology which does not solve the problem of truly simulta- neous voice and data. The sender must stop speaking in order to transmit data. Additionally, the technique is not sensitive to data backlog, and it does not exploit good channel conditions.

  Variable-Rate Speech Coding is another known technoiogy which depends on the time-varying entropy of the speech source. However, it does not exploit good channel conditions, and it is not sensitive to data backlog.

SOLUTION

  The voice coder, a voice FEC scheme, and a data FEC scheme along with the portion of the available throughput allocated to voice and to data may be dynamically selected according to: channel conditions, voice activity, data backlog, and voice/data priority as specified below.

  Before transmitting each transmission unit, the subscriber unit determines whether there is voice activity. If there is no voice activity, then the entire transmission unit is dedicated to data transmission or may be skipped to save battery power if no data is waiting for transmission. If there is voice activity and the data backlog does not exceed a backlog threshold, then the entire transmission unit is dedicated to voice transmission. If there is a data

backlog which exceeds a backlog threshold, then the subscriber unit must select from among a set of vocoder/FEC combinations and data FEC's for this transmission unit.

  For this proposed solution, there are N vocoder/FEC combinations delivering a range of trade-offs between data throughput and voice data error protection.

  For example, for iDEN we might have 3 FEC's used with the 3:l vocoder to allow 3 different com- promises between data and voice along with an iDEN 6: I vocoder option:

  Scheme 3-iDEN 6: I Vocoder using Current FEC Scheme wi 50% of 3: I slots allocated for data (lower 6: 1 voice quality may be acceptable in order to clear data backlog in low signal area

  Scheme 2-iDEN 3: 1 Vocoder using Current FEC Scheme (best voice quality, but no room for data)

Scheme l-iDEN 3:1 Vocoder with ACP symbol stealing (weakens error protection but opens

hole for data throughput)

  Scheme 0-iDEN 3:1 Vocoder with Group I and Group 2 data encoded using 64QAM rate 213 code. (further weakens error protection, but provides maximum simultaneous data throughput w/ 3: I coder among example schemes shown)

  The method for selecting between the available schemes involves calculating an est...