Browse Prior Art Database

Dynamic Time Slot Assignment Architecture for a Digital Telephone Switch

IP.com Disclosure Number: IPCOM000039534D
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Chang, LL: AUTHOR [+2]

Abstract

This article describes a technique of adaptive time slot assignment in a digital telephone switch which avoids assignment of slots to inactive user lines. In a conventional digital switching system, every line is assigned to a fixed time slot (TS) on a particular bus for receiving or transmitting digitized voice samples.

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Dynamic Time Slot Assignment Architecture for a Digital Telephone Switch

This article describes a technique of adaptive time slot assignment in a digital telephone switch which avoids assignment of slots to inactive user lines. In a conventional digital switching system, every line is assigned to a fixed time slot (TS) on a particular bus for receiving or transmitting digitized voice samples.

The call processor is programmed to handle the switching function by looking up the line/time slot table and exchanging the voice samples at the proper TS. Due to the nature of telecommunication traffic distribution, on most occasions only a portion of all the lines will be busy (e.g., only a portion of all time slots will be used in a conventional digital switching system) at any time. Those unused time slots at that specific time are wasted. The dynamic TS assignment method disclosed herein is an alternative to the conventional fixed TS assignment method. It utilizes the idea of sharing resources by dynamically assigning time slots to the lines that need to be served. In conventional systems using the newest technologies, a single line appearance uses a voice encoder/decoder (CODEC) attached to a single TS (1 out of 24, or 1 out of 32) on a particular bus. All time slots are assigned. Therefore, a bus may serve a maximum of 32 lines. The implied implementation is the standard mu-law, Pulse Code Modulated/Time Division Multiplexed bus assignments. In the implementation of this disclosure, each line appearance (line card) has access to two or more busses, each of which contain 32 unassigned time slots. As service is requested by a telephone user, an available TS on one of the busses is assigned to this call for the duration of the call. This is not the same concept as statistically multiplexing time slots on a dynamic basis as is used in satellite links. The number of potential line appearance users per bus should be greater than 32; how much greater depends on the traffic engineering for the switch application. The drawing shows the dynamic scheme of this disclosure in block diagram. Tri-state buffers 6 supply the paths of access. Each line of the system may have access to any TS on the same pulse code...