Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
1997-04-25
2001-04-10
Nguyen, Chau (Department: 2732)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S252000, C370S412000
Reexamination Certificate
active
06215767
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of telecommunications and in particular, to packet-based communications on multiple access networks.
BACKGROUND OF THE INVENTION
Asynchronous Transfer Mode (“ATM”) is a networking protocol designed to support high speed digital voice and data communications. It is generally believed that within the next several years, most of the voice and data traffic generated throughout the world will be transmitted by ATM technology. Broadband packet networks based on ATM technology are enabling the integration of traffic having a wide range of characteristics within a single communications network. In order to be accepted by potential end users and communication network providers, these ATM based broadband networks must meet certain performance requirements.
In general, an ATM bearer service, e.g., the broadband network, provides a sequence-preserving, connection-oriented cell transfer service between a source and destination with an agreed upon Quality of Service (“QoS”) and throughput. That is, the underlying layers of the ATM protocol should provide the convergence and transmission functions that would preserve the traffic shape and QoS of the traffic as the ATM cells are passed between the ATM layer and the underlying layers. Although the prior art discusses in great detail how these convergence and transmission functions are supported on a point-to-point medium, e.g., 155.52 Mbps on Synchronous Optical Network (“SONET”), 52 Mbps on Unshielded Twisted Pair (“UTP”), and 155 Mbps on fiber optic networks, etc., the prior art does not discuss how these same functions can be supported on multiple access networks.
In point-to-point medium systems, at connection set-up time, an end-user device negotiates with the network, at the network layer, certain QoS parameters, e.g., Cell Delay Variation (“CDV”), Cell Loss Priority (“CLP”), etc., and traffic descriptors according to the types of connection, e.g., circuit emulation, real-time video and audio, connection-oriented data transfer, connectionless data transfer, etc. Assuming a point-to-point connection at the User-Network Interface (“UNI”), the insertion of a cell for a particular connection is scheduled by the ATM layer and hence can be done completely under the control of the end-user device, following the negotiated contract with the network.
However, if the end-user device is attached to a multiple access network, such as a Hybrid Fiber/Coaxial network (“HFC”) or a Switched Digital Video (“SDV”) network, where multiple end-user devices access shared bandwidth, the traffic shape and QoS parameters may be temporally distorted at the insertion time as a result of bandwidth contention on the access network. Accordingly, there is a need to provide a simple and effective method which mitigates the effect of bandwidth contention on the shape of traffic and QoS parameters.
SUMMARY OF THE INVENTION
The present invention teaches a method and apparatus which mitigates the effects of bandwidth contention on the QoS and traffic shape on a multiple access network by temporally adjusting the delivery time of the cell. This method properly supports the convergence and transmission functions on a multiple access medium, such as a HFC network or the shared coaxial segment of a SDV network. Importantly, the present invention can be employed with any packet-based network, e.g., the Internet.
In an exemplary embodiment of the present method, a delivery time differential is computed between the intended transmission time of a cell and the time that the same cell is successfully transmitted on a multiple access network. The delivery time differential is communicated from the client terminal, where it is initially calculated, to the lost terminal side, which utilizes the delivery time differential to compensate for the time distortions resulting from multiple end-user devices accessing shared bandwidth on the multiple access network.
Advantageously, the method and apparatus of the present invention can be utilized with any mechanism employed for access to multiple access networks, e.g., contention-based mechanisms, permit-issuing or token-passing schemes. The above factors make the present invention a versatile and efficient method for maintaining the QoS and shape of traffic on a multiple access medium.
REFERENCES:
patent: 5483677 (1996-01-01), Brydon
patent: 5790543 (1998-08-01), Cloutier
Lucent Technologies - Inc.
Nguyen Chau
Vu Thinh
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