Browse Prior Art Database

ACTIVE DTE RECOVERY FROM SUSPEND

IP.com Disclosure Number: IPCOM000009577D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Sep-04
Document File: 2 page(s) / 102K

Publishing Venue

Motorola

Related People

Behzad Bamdad: AUTHOR [+3]

Abstract

In wireless, mobile data systems, such as Motorola's Private DataTAC system, messages flow from a fixed-location computer, through a radio net- work infrastructure, to a fleet of radio modems. Each radio modem is connected to a mobile comput- er (also known as Data Terminal Equipment or DTE). The protocol used on the radio channel will vary depending on the system, however, most are like Motorola's Radio Data Link Access Procedure (RD-LAP) in that they use a mechanism for posi- tively acknowledging (ACK'ing) successfully deliv- ered messages and negatively acknowledging (NACK'ing) those that are unsuccessfully delivered.

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Developments Technical m MOTOROLA

ACTIVE DTE RECOVERY FROM SUSPEND

by Behzad Bamdad, Wayne Lindemann and Steve Surwillo

BACKGROUND

  In wireless, mobile data systems, such as Motorola's Private DataTAC system, messages flow from a fixed-location computer, through a radio net- work infrastructure, to a fleet of radio modems. Each radio modem is connected to a mobile comput- er (also known as Data Terminal Equipment or DTE). The protocol used on the radio channel will vary depending on the system, however, most are like Motorola's Radio Data Link Access Procedure (RD-LAP) in that they use a mechanism for posi- tively acknowledging (ACK'ing) successfully deliv- ered messages and negatively acknowledging (NACK'ing) those that are unsuccessfully delivered.

  Presently, Motorola Private DataTAC radio modems can detect if a DTE is active and ready to receive messages (i.e., that it is physically connected and not in a power management "suspend" mode) by monitoring the Data Transmit Ready (DTR) sig- nal on the interconnecting RS-232 line. In this way, if DTR is present, the wireless modem knows the DTE is active and will therefore receive messages, ACK them and deliver them to the mobile user. If DTR is not present, the wireless modem knows the DTE is not active and will NACK messages until DTR is represented. Again, the DTE may be inac- tive because it is either not physically connected or it is in suspend mode.

MOTIVATION

  One shortcoming of this situation is that there is a significant difference between a DTE that is physi- cally disconnected from a radio modem and one that is connected but in a suspend mode. The former

obviously allows no immediate means of recovering communications between the DTE and the radio modem while the possibility for recovery does exist in the latter case of a connected but suspended state.

  The mechanism described below allows a radio modem to go beyond its current simple ability to sense the DTR signal by requiring that it attempt to wake a suspended DTE. This mechanism is enabled by the fact that most DTE devices (such as laptop compu...