Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing – Computer-to-computer handshaking
Reexamination Certificate
1997-11-26
2001-04-24
Burgess, Glenton B. (Department: 2153)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
Computer-to-computer handshaking
C709S239000, C348S086000, C348S014160, C348S014160, C348S014160, C348S086000, C370S228000, C370S261000, C370S251000, C340S870030, C714S004110, C714S005110, C714S006130
Reexamination Certificate
active
06223225
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates generally to dynamically adjustable hybrid two-way data networks, and more particularly pertains to dynamically adjustable hybrid two-way data networks.
The majority of residential customers can use 33.6 Kbps (and possibly 56 Kbps) dial-up telephone connections to on-line services. The popularity of the web has increased substantially the number of people served by on-line service providers, but the slow speeds associated with surfing the web and downloading information from it via telephone modems quite often make this experience a painful one. True interactive broadband services is out of the reach of the majority of small office/home office (SOHO) and general residential customers.
The development of cable modem technologies for hybrid fiber/coaxial (HFC) CaTV networks promises the advent of multi-Mbps interactive broadband services to residential customers. The exploitation of the large excess bandwidth on an HFC CaTV plant would permit customers to cruise the web and enjoy other interactive services at speeds that are 100-fold or more than what is possible today.
While two-way communications over the telephone network has been maturing for more than a century now, two-way communication networks based upon the CaTV infrastructure is still in its infancy. Considerable effort is required for developing not only the data transport mechanisms needed for transporting data back and forth over the shared-medium CaTV plant, but also the network management protocols which will guarantee high-availability of the CaTV plant for practically uninterrupted digital services to customers.
Due to the tree-and-branch topology of a CaTV network, there is no possibility of “re-routing” transmissions around a cut in the cable network. Hence, a single cut of the cable could throw a whole community of customers out of service for a long period of time. Even worse, the frequency spectrum from 5 to 42 MHZ which will be used for upstream transmissions, i.e., from the cable modem to the CaTV headend (H/E), is prone to ingress noise interference from unterminated CaTV outlets, ham radio, short-wave radio, impulse noise, etc. All of this noise is further amplified as it travels to the H/E due to the noise funneling effect.
2. Prior Art
Currently available static CaTV/PSTN (Public Switched Telephone Network) systems use PSTN for upstream transmissions, and the CaTV plant for downstream transmissions. The use of static hybrid networks with CaTV on the downstream side and PSTN on the upstream side has been introduced during the last few years to provide a fast entry to the interactive CaTV arena, with “off-the-shelf” solutions which do not require a fully two-way operational CaTV system.
U.S. Pat. No. 5,586,121 discloses static hybrid networks where the use of the same or a different communications channel is suggested for the forward and return channels. Also, U.S. Pat. No. 5,534,913 discloses an apparatus and method for integrating downstream data transfer over a cable television channel with upstream data carrier by other media. U.S. Pat. No. 5,488,412 teaches a customer premises equipment which receives high-speed downstream data over a cable television system and transmits lower speed upstream signaling on a separate channel.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide dynamically adjustable hybrid two-way data networks.
The present invention maintains a high degree of connectivity by providing a two-way CaTV system which uses the CaTV plant most of the time, but also uses the public switched telephone network (PSTN) as a back-up whenever upstream or downstream connectivity between a cable modem and the CaTV H/E is severed.
The present invention provides management elements for a fully operational two-way (HFC) CaTV network which uses PSTN connections as an “on-the-fly” back-up mechanism for the rare occasions that the CaTV plant looses its upstream and/or downstream connectivity. On the end-user side, a hybrid two-way CaTV/PSTN network (2w-hCPN) requires added intelligence in either the cable-modem box, which may be enhanced with a regular voice-grade modem, or in the PC attached to the cable modem, to automatically handle both communications media. Similarly, on the H/E side, a 2w-hCPN requires added capabilities for processing and managing both CaTV and PSTN connections as well as managing the transitions from one medium to the other and vice versa.
The present invention is not restricted to CaTV/PSTN dynamic networks only. Different types of hybrid networks, currently existing or developed in the future, can be utilized by the subject invention. For example, the present invention can use networks which use radio frequency (RF) for downstream transmissions and PSTN for upstream transmissions, or even hybrid networks which comprise more than just two different communications media. For these other hybrid networks, the subscriber and H/E equipment modem only needs to be replaced appropriately. Without excluding these other hybrid networks, a preferred embodiment of the invention focuses on 2w-hCPNs.
REFERENCES:
patent: 5210740 (1993-05-01), Anzai et al.
patent: 5534913 (1996-07-01), Majeti et al.
patent: 5675732 (1997-10-01), Majeti et al.
patent: 5859959 (1999-01-01), Kimball et al.
de Jong, et al. A CDMA Based Bidirectional Communication System for Hybrid Fiber-Coax CATV Networks, IEEE, pp. 127-135, Jun. 1997.
Bisdikian Chatschik
Maruyama Kiyoshi
Burgess Glenton B.
Cameron Esq. Douglas W.
International Business Machines - Corporation
Le Hien C.
Scully Scott Murphy & Presser
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