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Reduction Of The Effects Of Freeze-Out On Voice Channels

IP.com Disclosure Number: IPCOM000048035D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Brennen, JF: AUTHOR [+3]

Abstract

Modern time division multiple access (TDMA) communications controllers move information from voice and digital data ports to a burst modem under the control of a control processor via parameters which are specified by the processor and retained in a sequentially addressed switch control memory (SCM). These parameters specify a specific port and where information from that port is to be retained prior to transfer to the burst modem via a transmit burst buffer.

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Reduction Of The Effects Of Freeze-Out On Voice Channels

Modern time division multiple access (TDMA) communications controllers move information from voice and digital data ports to a burst modem under the control of a control processor via parameters which are specified by the processor and retained in a sequentially addressed switch control memory (SCM). These parameters specify a specific port and where information from that port is to be retained prior to transfer to the burst modem via a transmit burst buffer.

In a given TDMA frame, not all active ports require transmission of a channel due to voice activity compression (VAC) and data activity compression (DAC). Advantage is taken of this fact, and as a result, the communications controller will have fewer channels allocated to it than would be required if the ports operated without VAC and DAC. It is possible, therefore, that the number of channels to be sent may exceed the number allocated to the communications controller. Those ports with channels which require transmission but were not sent are referred to as being frozen out.

Freeze-out of a channel can be applied on a priority basis with the lowest priority messages being frozen out first. Since voice messages can undergo the freeze-out operation for small segments without substantially impairing the intelligibility of the speech transmission, voice traffic can be preferentially frozen out during periods of peak transmission density.

To assure that high priority data channels are transmitted without interruption, the switch control memory (SCM) scans those portions corresponding to the data ports first. The SCM scanning cycle is in synchronization with the transmission frames. The locations in the SCM corresponding to the voice ports are then scanned, and thus voice channels are transmitted in the latter portion of each TDMA burst. If a peak in data transmission activity occurs during a particular frame, those voice channels occurri...