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A METHOD, UTILIZING MULTICASTING OF DATA, FOR ALLOWING SUBSCRIBER SCAN OPERATION IN A CONVENTIONAL INTEGRATED VOICE / DATA SYSTEM

IP.com Disclosure Number: IPCOM000008358D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2002-Jun-10
Document File: 2 page(s) / 107K

Publishing Venue

Motorola

Related People

Mark D. Chapman: AUTHOR

Abstract

Today's conventional voice / data systems allow a subscriber to use scan for voice operations. However scan is not allowed when data reception is a requirement. This is due to the fact that an outbound data message packet is an unsolicited asynchronous event that is difftcult to receive with zero errors while in scan. The act of changing fre- quencies is bound to leave the radio in most cases either on the wrong frequency or appearing on the correct frequency at the wrong time so as to miss important parts of the data packet. This results in missed packets and an avalanche of retries developing in the system.

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m MO-LA Technical Developments

 A METHOD, UTILIZING MULTICASTING OF DATA, FOR ALLOWING SUBSCRIBER SCAN OPERATION IN A CONVENTIONAL INTEGRATED VOICE / DATA SYSTEM

by Mark D. Chapman

  Today's conventional voice / data systems allow a subscriber to use scan for voice operations. However scan is not allowed when data reception is a requirement. This is due to the fact that an outbound data message packet is an unsolicited asynchronous event that is difftcult to receive with zero errors while in scan. The act of changing fre- quencies is bound to leave the radio in most cases either on the wrong frequency or appearing on the correct frequency at the wrong time so as to miss important parts of the data packet. This results in

missed packets and an avalanche of retries developing in the system.

  Simply allowing data reception will not work due to the low probability of the subscriber radio being on the correct channel at just the right time to receive the start of the correct data packet destined for that radio. In order to bring this reliability up to an acceptable level a means must be found to acquire the attention of the subscriber unit without unneces- sarily clogging up the channel with data traffic.

Ch2

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i3

Ch 1

?I Ch3

  Let's use the case of a subscriber unit with a 3 channel scan list as shown above as an example. Each of the transmitter channels is an integrated voice and data channel. As such all of the channel's Base Stations are tied via the infrastructure links to a Data Network Controller. It is the function of this controller to route data messages between various subscriber units and a set of host computers. At any point in time the subscriber may actually be listen- ing to any one of the channels.

  Today's data systems use confirmed messaging in order to transport the user data across the RF link. This insures that no data is lost in the hostile RF environment. By taking advantage of the confirmed nature of the traffic the Data Network Controller requires the correct outbound path to be used to find a subscriber unit each time an outbound packet is acked by the subscriber or when the subscriber unit initiates sending in a packet

'e Motorola, ,"C. 1997 183 September I997

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