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A RECONFIGURABLE CENTRAL RESOURCE SYSTEM

IP.com Disclosure Number: IPCOM000006434D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2002-Jan-03
Document File: 4 page(s) / 158K

Publishing Venue

Motorola

Related People

Steven J. Goldberg: AUTHOR

Abstract

Digital Signal Processors are being widely used in telecommunication systems. They provide a great deal of flexibility for adding new features, making adjustments in implementations, and eliminating hardware by recoding the same device to perform multiple functions.

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MOTOROLA INC. Technical Developments Volume 15 May 1992

A RECONFIGURABLE CENTRAL RESOURCE SYSTEM

by Steven J. Goldberg

  Digital Signal Processors are being widely used in telecommunication systems. They provide a great deal of flexibility for adding new features, making adjustments in implementations, and eliminating hardware by recoding the same device to perform multiple functions.

  Systems which benefit from these advantages often have the structure shown in Figure 1. Since the proces- sor is restricted to one communications path it must be able to handle the most demanding task that it could be expected to perform. An example b&g a telephone inter- face in a Paging System. A partial list of system require- ments is: Tone Generations, DTMF Detection, audio compression/expansion, Modem. etcetera.

  Since a Modem is otten the most demanding realtime function, the DSP must have the memory, speed, and characteristics for this use. A system however which did not require the Modem (or perhaps only a slower speed type) would be burdened by the overhead of a capability it did not require. (The option of modiing the hardware according to use is not desirable because of manufacturing, distribution, and support issues.)

  General telephone switching systems do not require as many functional units as there are possible commu- nication paths. This is true because functions such as DTMF decoders are typically used only for a fraction of a telephone call period. Statistically it has been found that a significantly smaller number of functional units can be provided, and randomly assigned as required. The resultant blocking is usually unnoticed by the users. The switching systems often provide functions as banks of Central Resources. Available units are therefore switched to ports requiring service dynamically (Figure 2).

  Paging Systems however have different functional utilizations than a standard telephone exchange. DTMF decoding, tone generation, etcetera are usually used a significant portion of a user access. A one to one capa- bility between function and port must therefore be maintained to prevent blocking due to lack of resources.

  Figure 3 shows the basic board of a system with superior set of attributes. It is a central resource card in the same general sense as that shown in Figure 2.

There are however several key implementation differences:

1. Digital Signal Processors are used to allow diier- ent digitized analog functions to be implemented.

2. The Time Slot Interface block allows for one or more time slots to be routed between the TDM bus and the DSP

3. The utilization of the DSPs can be both system requirement dependent, and dynamically assign- able dependent.

4. DSP pairs have a high speed interface between them. Their use or lack of it is functionally dependent.

5. A control type processor is provided which has common access to the N DSP processors on a card. This allows local control over the line and slot switching, and aS a communi...