Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1999-10-15
2001-05-29
Hsu, Alpus H. (Department: 2662)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S376000, C370S401000, C370S410000, C370S467000, C709S249000
Reexamination Certificate
active
06240086
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to digital signal processors used for allocation of resources. More particularly, the present invention is a gateway that controls and allocates a single function for each digital signal processor in a flexible manner to implement a multi-function system for transmitting Time Division Multiplexed (TDM) telecommunications over a packet network.
2. Background Information
As telecommunication technology advances, the demand for cheaper, better, and more telecommunication services increases. In the past, separate telephone and facsimile lines were sufficient for a business. Today, separate telephone and facsimile lines are insufficient even for a residence. In today's society, businesses and residences need separate telephone, facsimile, and data lines just to keep up with technology.
Thus, as the demands for telecommunication services rise, so does the demand for more telecommunications lines. As society continues to become computer savvy, the demand for more telecommunication lines is becoming an increasing problem. In short, present day telecommunication demands are becoming harder to meet.
To meet some of society's needs, businesses and residences are turning to alternative telecommunication services, such as satellite services, instead of the traditional means, i.e., telephone lines. However, even these alternative telecommunication services are insufficient to meet society's needs. Telephone companies are running out of telephone numbers, modems are becoming outdated quicker than ever, and the demand for telecommunication services continues to rise with no end in sight.
One traditional way to improve telephone service has been through the use of Time Division Multiplexed (TDM) telephony networks. TDM is based on allocating a time slot for each channel connected to the system whether the user uses the allocated time slot or not. However, even with the improvements afforded by TDM technology, telephony systems are still expensive and cannot provide sufficient telecommunication services. As a result, there is a need to migrate from the traditional TDM telephony network towards a packet based network for carrying telecommunication information such as voice/fax/data information.
A packet system adds a header to the information payload to form an information packet, and sends the information packets to a desired location. The packets can vary in size or they may be a set size. If there is too much information to fit into one packet, the information is broken up into several packets with each packet having a header thereby allowing assembly into a coherent file later. At a minimum, the header indicates where the packet is being sent and the relative ordering of the packets. Once packets are received at the desired destination, the packets are then recombined in the proper order. Ideally, packet based systems are high density and low power.
The requirement to have high density and low power for the packet based network is complicated by the desire to have a flexible system that performs many different functions on a per channel basis. The goal is to have a system that can provide a wide variety of functions per channel. For instance, it is desirable to have a system that can be used with voice coders, fax modems, and data modems, as well as operating to accommodate different standards or versions.
The system uses a universal port to handle the different types of telecommunication information. In order to deliver the different telecommunication information, the universal port accommodates different functions on a per channel basis. To make such a system, digital signal processors (DSPs) are used for processing the different telecommunication information through multiple channels. One approach is the use of multi-function, multi-channel DSPs where all functions are available at any time on all DSP channels, i.e., all of the software for running the system is present on each DSP.
Referring to
FIG. 1
, a multi-function, multi-channel DSP system architecture is illustrated. According to this approach a universal port is implemented having all functions available at all times on a given DSP. As illustrated, the microprocessor
100
contains DSP control software
102
that controls which DSP function is running at any particular time, with all of the functions being available at all times on the DSP. In this example, the DSP
104
can run functional software to handle G.729A voice compression/decompression
106
, fax traffic
108
, G.723.1 voice compression/decompression
110
, or modem traffic
112
. Similarly, the DSP
114
can run functional software to handle G.723.1 voice compression/decompression
116
, modem traffic
118
, G.729A voice compression/decompression
120
, or fax traffic
122
.
In operation, information to and from physical devices, such as a modem
126
, a telephone
128
, and fax machine
130
, pass through a TDM input
124
and the individual DSPs (
104
,
114
) for processing. The TDM input
124
assigns times slots for each physical device. In this case, each physical device is assigned a time slot regardless of whether that physical device is in use or not.
The DSP control software
102
in microprocessor
100
determines which function each of the channels in each DSP will operate to process. For example, the DSP
104
can be running voice compression/decompression according to G.729A on channel
1
, fax relaying on channels
2
and
3
, and a V.90 modem on channel
4
. The processed information is passed to and from an Internet Protocol (IP) network
132
. The IP network
132
may be a WAN or LAN type of IP network.
An advantage of this approach is that any channel within a DSP can be executing any of the configured algorithms. The disadvantage of this approach in DSP utilization is that it is expensive to have all of the algorithms available for use at all times on a large array of individual DSPs. This approach is also an inefficient use of both memory and power. The increased cost in terms of money, space, and power is a function of the product of the number of channels and the number of functions supported.
Therefore there is a need for a gateway that interfaces between traditional telephone equipment and a packet network, which processes and translates telephone network information to packets, and which does so in an efficient manner.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a gateway that allows telecommunication information from a TDM system to be transmitted over a packet network.
It is still a further object of the present invention to use a universal port to allow various forms of telecommunications to be sent over a packet network.
It is still a further object of the present invention to use single-function, multi-channel DSP system that includes a plurality of DSPs with each DSP running a single function on all of the channels in the particular DSP thereby, transmitting telecommunications information over a packet network.
The present invention is a gateway that allows packets to be sent over a TDM system. The gateway is a universal port that includes a plurality of DSPs that are controlled by software. The controlling software determines what single function the DSP will perform over multiple channels.
Some of the above objects are achieved by a telecommunications gateway for interfacing telecommunications traffic between a TDM network and a packet switched network. The telecommunications gateway includes a time slot interchanger, plural DSPs and a microprocessor controller. The time slot interchanger is connected to handle traffic from the TDM network. The plural DSPs are connected to handle TDM traffic routed according to allocation of time slots by the time slot interchanger. The plural DSPs convert TDM traffic into packets for transport via the packet switched network and converting packet traffic from the packet switched network for transport via the TDM network. The microprocessor operates according
Crupi Joseph
Morgan Edward
Witowsky William
Brady III Wade James
Franz Warren L.
Hsu Alpus H.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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