Multiplex communications – Channel assignment techniques – Using time slots
Reexamination Certificate
1998-08-03
2004-06-08
Jung, Min (Department: 2663)
Multiplex communications
Channel assignment techniques
Using time slots
C370S468000
Reexamination Certificate
active
06747985
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to communications networks and, more specifically, to an Ethernet network topology optimized for handling telecommunications traffic.
BACKGROUND OF THE INVENTION
In 1996, more than 75 million people worldwide used cellular telephones. Reliable predictions indicate that there will be over 300 million cellular telephone customers by the year 2000. Within the United States, cellular service is offered not only by dedicated cellular service providers, but also by the regional Bell companies, such as U.S. West, Bell Atlantic and Southwestern Bell, and the national long distance companies, such as AT&T and Sprint. The enhanced competition has driven the price of cellular service down to the point where it is affordable to a large segment of the population.
This competition has also led to rapid and sweeping innovations in cellular telephone technology. Analog cellular systems are now competing with digital cellular systems. Heavy investments are being made in TDMA, CDMA, FDMA, and other similar technologies. Increasingly, the cellular telephone system is being used to handle high bandwidth traffic, such as video and data, in combination with traditional voice traffic.
A wide variety of wireline backbones have been proposed to support the different requirements of different types of wireless traffic. For example, CDMA telecommunications equipment requires very reliable, high capacity, fast throughput, low delay, and simple connections for voice and signaling traffic, while command and control message traffic is typically less bandwidth demanding and can tolerate higher delays. These diverse requirements may result in two networks being implemented: one for voice and signaling traffic and one for command and control messages. In such an implementation, a star network architecture may be more suitable for one type of data traffic and a ring network architecture may be more suitable to another type of data traffic.
The comparative advantages and disadvantages of star and ring architectures are well-known. In an Ethernet star topology, for example, each interface on the network server provides a point-to-point connection between the server and a single client device, or node. Thus, the server requires a separate interface for each client device. There are numerous advantages to this star architecture. Bandwidth is available on demand on each client connection, since there are no other devices with which to contend. This results in high utilization and a fixed delay for each client connection. Additionally, the failure of single node will not interfere with communications between the server and another node.
However, the point-to-point connection also increases hardware costs, since each client requires a separate interface; increases power consumption, and, as a practical matter, limits the expansion capability of the network. The point-to-point connection also means that node-to-node communication is a multiple step process requiring the involvement of the network server. This increases processing requirements and allows a single point of failure for all network routing.
In an Ethernet ring topology, the network server and all client nodes are connected via individual interfaces to a common interconnection bus. The server and each node have an address on the common bus and communications layer addressing provides point-to-point communications. The server and the client nodes each have routing tables containing addresses of other devices. There are numerous advantages to the ring architecture. The server requires only one interface, thereby reducing hardware costs and power consumption. The shared interconnection bus allows for easy expansion of the network to a comparatively large size. Nodes can communicate directly, without intervention by the server. Additionally, failure of the server or an individual client device will completely shut down the network.
However, in a ring topology, bandwidth is limited due to the contention-oriented nature of shared bus communications. Each client node can access the common ring independently, thereby causing collisions and delays of variable and unpredictable length. Also, a failure of the communication interface of even a single node or the server can cause a hang-up on the common bus, thereby causing a communication failure for the entire network.
There is therefore a need in the art for an improved communication network that achieves the benefits of both a ring architecture and a star architecture, while eliminating or minimizing their attendant drawbacks. In particular, there is a need in the art for an improved Ethernet interconnection network that for use in a wireless communication network, such as a CDMA telecommunications network.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to provide, for use in a communication network, a network communications manager capable of controlling data transfers among a server and a plurality of client nodes coupled by a network ring. The network communications manager comprises a time quanta controller capable of dividing a time frame on the network ring into distinct time quanta and assigning to each of the plurality of client nodes a predetermined time quantum during which the each of the plurality of client nodes may transmit data.
According to one embodiment of the present invention, the predetermined time quantum has a minimum duration to thereby ensure that the each of the plurality of client nodes is able to communicate for a minimum-length time quantum during each time frame.
In another embodiment, the time quanta controller assigns to the server a predetermined time quantum during which the server may transmit data.
According to another embodiment of the present invention, the time quanta controller is capable of assigning to each of the plurality of client nodes an additional time quantum during which the each of the plurality of client nodes may transmit data.
In still another embodiment of the present invention, the predetermined time quantum and the additional time quantum allocated to each client node occur sequentially.
In yet another embodiment of the present invention, the time quanta controller is capable of assigning to the server an additional time quantum during which the server may transmit data.
According to a further embodiment of the present invention the predetermined time quantum and the additional time quantum allocated to the server occur sequentially.
In a still further embodiment of the present invention, the network communications manager transmits a synchronization signal on the network ring capable of synchronizing data transmission by the server and the plurality of client nodes.
The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
Before undertaking the DETAILED DESCRIPTION, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is, inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or
Jung Min
Lee Andy
LandOfFree
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