Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
2000-07-18
2004-08-24
Duong, Frank (Department: 2666)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S535000
Reexamination Certificate
active
06782002
ABSTRACT:
BACKGROUND
The present invention relates generally to providing a customer with a first type of access to a network when lines that typically provide the desired access are not available between the customer's premises (CP) and a point of presence (POP) (or central office (CO)) associated with the network. More particularly, the present invention relates to utilizing a single multiplexer at a CP to map two or more lines of the first type of data onto three or more lines that typically provide another service and utilizing a single multiplexer at a network POP (or CO) to receive the data from the three or more lines that typically provide another service and map the data back onto the original number of lines.
In Europe, the most popular standard for transmitting digital voice data is known as E1. E1 was devised by the International Telecommunications Union—Telecommunication Standardization Sector (ITU-T). The name E1 was given by the Conference of European Postal and Telecommunication Administration (CEPT). In accordance with the E1 standard, 32 standardized 64 Kbps channels (also referred to herein as “timeslots”) carry digital data at a rate of 2.048 Mbps. In the United States, the most popular standard for transmitting digital voice data is known as T1. T1 was introduced by the Bell System in the 1960's. In accordance with the T1 standard, 24 standardized 64 Kbps channels carry digital data at a rate of 1.544 Mbps.
Although many networks in the United States (such as the AT&T network) are able to accommodate the transmission of E1 format data, many customers in the United States are unable to obtain an E1 line between their CP and a POP or CO associated with these E1-compatible networks. The United States customer may desire an E1 line so that they might transmit E1 format data from their CP to a location in Europe. One known solution to this problem is to provision two T1 lines between the CP and the POP for each desired E1 line. A first multiplexer at the CP puts an E1 onto the two T1s. A second multiplexer at the POP recreates the E1 from the two T1 lines. Thus, 48 T1 channels are utilized to transport 32 E1 channels between the CP and the POP. With this solution, managing the number of T1s and multiplexers becomes more burdensome as the number of E1 s increases. For three E1s, for example, six T1s and six dedicated multiplexers (three at the CP and three at the POP) are required and 144 data channels of the six T1 s are used to transport the 96 channels of the three E1 s.
Another current solution is to provision a T3 (45 MB) line between the network POP and the CP, utilize a multiplexer at the CP to put the E1 data onto the T3, and utilize a second multiplexer at the POP to extract the E1 data from the T3. The extracted E1 data is then transported over the network. One of the drawbacks of this solution is the monetary cost. Even without factoring in the monetary cost of the multiplexers, this solution is not cost-effective when less than eight E1 lines are involved.
Yet another known solution is to provision T1 lines between the CP and the POP, install a cross-connect box at the CP, use the cross-connect box to connect each individual channel of each E1 line to a corresponding mapped channel of the provisioned T1 lines, and (at the POP or elsewhere in the network) cross-connect the T1 channels to E1 channels. In addition to being highly complex and monetarily expensive, this solution requires implementing a service not currently provided by the long-distance carrier.
In view of the above, it can be appreciated that there is a need for a method and apparatus which solves the above described problems.
SUMMARY OF THE INVENTION
According to one embodiment of the present invention, a single multiplexer at a customer premises (CP) and a single multiplexer at a network point of presence (POP) are utilized to provide E1 access between the CP and the network POP. Each multiplexer comprises three E1 interfaces and four T1 interfaces. One separate E1 line from the CP is connected to each of the three E1 interfaces of the CP multiplexer. Similarly, one E1 line from an E1-compatible network is connected to each of the three E1 interfaces of the POP multiplexer. Each of the four T1 interfaces of the CP multiplexer is connected to one of the four T1 interfaces of the POP multiplexer. The CP multiplexer receives data from the three CP E1 lines and maps this data onto the four T1 lines. The POP multiplexer receives the data from the four T1 lines and maps the data onto three network E1 lines. In a similar manner, the CP multiplexer and the POP multiplexer enable E1 format data to flow from the network POP to the CP.
REFERENCES:
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patent: 5799019 (1998-08-01), Kim et al.
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patent: 6122288 (2000-09-01), Dashiff et al.
RAD Data Communications, IMX-4T1, T1 Inverse Multiplexer, pp. 1-A10, 1999.*
Digital Link Corporation, IMUX Fundamentals, pp. 1-60, 1999.
AT&T Corp.
Duong Frank
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