Title of Invention	A METHOD FOR PROVIDING WARNING OF IMPAIRED COMMUNICATION IN A DEVICE FOR BI-DIRECTIONALLY COMMUNICATING WITH A REMOTE SITE
Abstract	This invention relates to a method for providing warning of impaired communication in a device for bi-directionally communicating with a remote site, the method comprising: retrieving a communication parameter value from a memory; comparing said retrieved parameter value indicative of a potential communiction link impairment; and initiating substantially periodic transmission of a message to said remote site indicating a system adjustment is necessary, in response to said comparison.

Title of Invention

A METHOD FOR PROVIDING WARNING OF IMPAIRED COMMUNICATION IN A DEVICE FOR BI-DIRECTIONALLY COMMUNICATING WITH A REMOTE SITE

Abstract

This invention relates to a method for providing warning of impaired communication in a device for bi-directionally communicating with a remote site, the method comprising: retrieving a communication parameter value from a memory; comparing said retrieved parameter value indicative of a potential communiction link impairment; and initiating substantially periodic transmission of a message to said remote site indicating a system adjustment is necessary, in response to said comparison.

Full Text	Communication Parameter Adjustment System in an Internet-Compatible Bi directional Communication System Field of the Invention This invention concerns a system for use in interactive bi-directional communication in a device such as a cable modem, computer, TV, VCR, or an associated peripheral device. Home entertainment systems that combine Personal Computer and television functions (PC/TV functions) are increasingly becoming generic, User interactive, multiple source and multiple destination communication devices. Such systems are required to communicate in different data formats between multiple locations for a variety of applications in response to User requests. For example, a system may receive data from satellite or terrestrial sources comprising High Definition Television (HDTV) broadcasts, Multi-point Microwave Distribution System (MMDS) broadcasts and Digital Video Broadcasts (DVB). A system may also receive and transmit data via telephone (e.g. the Internet) and coaxial lines (e.g. cable TV lines via a cable modem) and from both remote and local sources such as Digital Video Disk (DVD), CDROM, VHS and Digital VHS (DVHS™) type players, PCs, and many other types of sources. It is desirable for Internet compatible bi-directional communication systems that are used in conjunction with home entertainment systems to accommodate the network cable length and associated transmission power level variation occurring in a cable distribution network. This requirement and associated problems are addressed by a system according to the present invention. A system adaptively varies upstream transmission power level to prevent communication interruption in a cable modem network. A method for i adaptively adjusting communication operation by varying a transmission parameter involves retrieving a communication parameter from memory and comparing the retrieved parameter with a predetermined threshold. A message is transmitted to a CATV head-end at a remote site representing that the parameter value indicates adjustment of the parameter is necessary. Brief Description of the/Drawings In the drawing: Figure 1 shows a block diagram of a cable modem incorporating adaptive upstream transmission power level adjustment, according to the invention. Figure 2 shows a cable modem start up sequence, according to the invention. Figure 3 presents a flowchart of a method for adaptively adjusting i upstream transmission power level, according to the invention. Figure 1 shows a block diagram of a cable modem (e.g. DOCSIS standard compliant modem) capable of adaptively varying transmission power level of signals transmitted by the modem to the CATV head-end. The cable modem provides a communication bridge between a cable TV system and a PC (or another device such as a TV), for example. The modem communicates with the cable system head end via SNMP (Simple Network Management Protocol). The disclosed power level adjustment system reduces cable modem service interruption for subscribers. This is accomplished by providing the cable operator with an "early warning" that the transmission power level is operating too close to a performance threshold and that, as a result, a service interruption may occur soon. The particular threshold concerned is a settled upstream transmit power level from the modem to the CATV head-end. Cable operator upstream path problems are a common cause of service interruption to subscribers due to improper upstream path gain or loss between particular cable modems in the cable network and the cable operator head-end. This problem may be caused, for example, by technician mis- adjustment of cable plant amplifiers and RF splitting or combining networks. The described cable modem system advantageously automatically senses and reports problems to a central cable operator network management station. Thereby the disclosed system operates with fewer subscriber service interruptions, improves system up-time, and forestalls out-of-service conditions by detecting and correcting such conditions before they result in subscriber service interruption. The exemplary embodiment of Figure 1 supports cable modem communication and decoding of data in hierarchically arranged protocols including TCP/IP (Transmission Control Protocol/Internet Protocol), Ethernet and MPEG (Motion Picture Experts Group) protocols (e.g. per MPEG2 ISO/TEC 13818-1 of 10th June 1994, and ISO/IEC 13818-2, of 20th January 1995). In addition, the system of Figure 1 is compatible with the Multimedia Cable Networks Systems (MCNS) preliminary requirements and DOCSIS 1.0 (Data Over Cable Service Interface Specification 1.0) requirements ratified by the International Telecommunications Union (ITU) March 1998 and associated EuroDOCSIS requirements and other documents provided by the IETF (Internet Engineering Task Force) RFCs (Requests For Comment) such as RFC 2669. The RFC documents are available via the Internet and are prepared by Internet standards working groups. The principles of the invention may be applied to any bi-directional communication system and are not restricted to cable, ADSL, ISDN, conventional type modems or DOCSIS compatible modems. Further, the disclosed system processes Internet Protocol (IP) data from a variety of Internet sources including streamed video or audio data, telephone messages, computer programs, Emails or other packetized data and communications, for example. The cable modem (system 12) of Figure 1 communicates with a CATV head-end over a bi-directional broadband high speed RF link on line 10 which typically consists of coaxial cable or hybrid fiber/coax (HFC). The modem system 12 bi-directionally communicates with devices located at a User site over local area networks (LANs). Typical User-side local area networks include Digital/Intel/Xerox Ethernet compatible networks attached via connector 72. Other User-side devices communicate via a Universal Serial Bus (USB) or HPNA (Home Phone Line Network Association) compatible networks attached via connectors 82 and 77 respectively. User devices attached on the Ethernet, HPNA and USB networks may include equipment such as personal computers (PCs), network printers, video receivers, audio receivers, VCRs, DVDs, scanners, copiers, telephones, fax machines and home appliances, for example. In operation, diplexer 20 of cable modem system 12 of Figure 1 separates upstream communications (sent from modem 12 to a CATV head-end) from downstream communications (sent from a CATV head-end to modem 12) conveyed via cable line 10. Diplexer 20 separates upstream data from downstream data based on the different frequency ranges that the upstream data (typically 5-42 MHz) and downstream data (typically 88 - 860 MHz) respectively employ. Controller 60 configures the elements of cable modem 12 of Figure 1 to receive DOCSIS/MPEG2 transport data from the CATV head-end on cable line 10 and to convert the data to Ethernet, USB or HPNA compatible format for output via ports 72, 82 and 77 respectively. Similarly, controller 60 configures the elements of cable modem 12 of Figure 1 to receive Ethernet, USB or HPNA compatible data from ports 72, 82 and 77 and to convert and transmit DOCSIS transport protocol data to the CATV head-end on cable line 10. Controller 60 configures the elements of system 12 through the setting of control register values within these elements using a bi-directional data and control signal bus. Specifically, controller 60 configures tuner 15, saw filter 25, differential amplifier 30 and MCNS (Multimedia Cable Networks Systems) interface device 35 to receive a DOCSIS formatted signal on a previously identified RF channel frequency. The DOCSIS formatted signal comprises an MPEG2 transport protocol format conveying Ethernet compatible data frames including IP data content. Controller 60 employs the process shown in Figure 2 for initializing system 12 of Figure 1 and for selecting an initial power transmission level for transmitting of signals from system 12 to the CATV head end. Specifically, Figure 2 shows a series of operational states through which the Figure 1 DOCSIS compliant cable modem system 12 progresses during startup to become fully operational. Upon application of power to modem system 12 in step 250 of Figure 2, controller 60 executes bootloader software uploaded from flash memory within unit 60 to set all modem components to their initial power on condition. In step 255 of Figure 2, controller 60 (Figure 1) directs system 12 in determining the RF channel frequency that tuner 15 is to be configured to receive by iteratively tuning to successive candidate RF channel frequencies until a DOCSIS compliant signal is obtained. Controller 60 recognizes a DOCSIS compliant signal on a candidate channel through the successful decode by MCNS interface processor 35 of the received data and through a correspondingly acceptable error rate for the decoded data. In step 260 of Figure 2, controller 60 initiates Ranging by directing system 12 in transmitting data upstream to the CATV head-end using MCNS interface 35, amplifier 85 and RF transformer 87. The Ranging function involves adaptively and iteratively adjusting upstream and downstream communication parameters including cable modem transmission power level and timing offset. Specifically, system 12 incrementally increases the power level of signals conveying status messages periodically transmitted to the CATV head end. This is done until system 12 receives an acknowledgement from the CATV head end indicating that the messages are successfully received. The CATV head-end determines when Ranging is completed and communicates that Ranging is terminated to system 12. At completion of Ranging, communication between system 12 and the CATV head-end involving Media Access Control (MAC) layer protocol is established. In step 265 of Figure 2, controller 60 initiates Connecting by directing system 12 in establishing bi-directional communication between modem system 12 and the CATV head-end involving DHCP (Dynamic Host Configuration Protocol) communication with a remote DHCP server. Specifically, the system 12 IP (Internet Protocol) address and other configuration parameters are acquired from the DHCP server and stored in memory within unit 60. Upon successful completion of the Connecting process, the cable modem is operable as an Internet host, and has an assigned IP address. In step 270 of Figure 2, controller 60 initiates Configuring by acquiring the date and time from a remote internet TIME server using internet TIME protocol and by downloading a Configuration File for modem system 12 from a remote TFTP (Trivial File Transfer Protocol) server using TFTP. The configuration file includes SNMP compatible data conveying threshold values defining warning zones near the minimum and/or maximum operational limits for the power level to be used in transmitting signals from system 12 to the CATV head end. System 12 sends alert messages to the CATV head end if the transmission power level used by system 12 exceeds these threshold values and the power level lies within a warning zone. SNMP messages may also be used to activate and deactivate the alert messages and threshold comparison mechanism and to adjust thresholds and message repetition rate after initialization or at other times of modem operation. The configuration file SNMP data may also determine the repetition frequency at which alert messages (including the actual power level value employed by system 12) are transmitted to the CATV head end. The DOCSIS standard allows parameters such as the transmission power level threshold values and alert message repetition frequency to be incorporated into the mandatory configuration file that a cable modem downloads during its startup. Thereby the threshold and repetition frequency values may be advantageously set automatically each time a cable modem is installed and performs its DOCSIS initialization routine. If no threshold values or alert message repetition data is provided in the configuration file then predetermined default settings contained in system 12 memory are used. Upon completion of the Configuring operation, modem system 12 has received and stored sufficient information to become operational and is in condition to receive a signal from the CATV head-end to initiate becoming fully on-line and operational. In step 275 of Figure 2, controller 60 initiates Registering by directing system 12 in communicating key configuration parameters applied by the modem system 12 to the CATV head-end for final acceptance. The CATV head-end compares the configuration parameters employed by system 12 with the configuration parameters previously supplied from the CATV head-end to system 12. Upon determining that they match, the CATV head-end notifies system 12 that registration is completed and that system 12 is on-line and operational. The process of Figure 2 is complete at step 280. Figure 3 shows a flowchart of a method for use by system 12 (Figure 1) for monitoring the upstream transmitter power level of a DOCSIS-compliant cable modem and for automatically sending a warning at predetermined intervals to a CATV listening network management station if a settled power level falls outside a range of acceptable values. The DOCSIS standard requires that a compliant cable modem supports Simple Network Management Protocol (SNMP) as well as related software procedures and virtual data stores of cable modem operating information termed Management Information Bases (MIBs). The MIBs allow remote management of cable modem operations by a management station, operated from the cable head- end, or by a network operations center controlled by an Internet service provider, for example. Further, some MIBs may be defined by a modem provider. The method of Figure 3 is implemented in the form of a collection of settable MIB objects executed by controller 60 (Figure 1). In step 205 of Figure 3, following the start at step 200, if no power threshold values or alert message repetition data is provided in the configuration file received during initialization, controller 60 configures system 12 with default values. The power threshold values determine alert thresholds for the power level used in communicating signals from system 12 to the CATV head end. Also the repetition data determines the frequency at which alert messages (including the actual power level value employed by system 12) are transmitted to the CATV head end. The default values may be predetermined by a modem provider and may be viewed (or may be set in non-DOCSIS compatible applications) by User operation of an attached PC (e.g. attached to port 72 - Figure 1) through a private MIB. In step 210, the power threshold values or alert message repetition data, in use by system 12, may be accessed and viewed on a web page generated by system 12 for display on an attached PC in response to a User command via the PC. The displayed web page may be employed as the User interface supporting User viewing of these values and also, in non-DOCSIS compatible applications, the selection and update of these values. In step 215, controller 60 periodically reads the current upstream transmit power level and in step 220, compares this power level with the thresholds previously obtained in step 205. In another embodiment, the period at which this comparison is made may also be defined by a User via a configuration file or default setting or by User data entry via an attached PC. If the comparison indicates that the power level is in a warning zone, i.e. is at or above a maximum threshold, or is at or below a minimum threshold, controller 60 initiates sending of an alert message to the CATV head end in step 225. The thresholds may be selected, for example, so that an alert message is generated if the settled operating cable modem upstream transmit power is 10 dBmV or below (compared to a DOCSIS specified minimum of 8 dBmV) or 54dBmV or above (compared to a DOCSIS specified maximum of 58 dBmV). The alert message is automatically sent to the CATV head end as a SNMP compatible message (termed a Trap) at a repetition frequency (e.g. every 3 minutes) defined by the configuration repetition data obtained in step 205. The message is repeated until cable system adjustments are made that result in clearance of the condition causing the alert message. Once this occurs controller 60 periodically executes steps 215 and 220 and the alert message transmissions generated in step 225 cease. The frequency at which the power level is checked in steps 215 and 220 is determined by a configuration file parameter, or by a default value. Note, a Trap is an SNMP message type defined in the SNMP protocol that can be launched by a networking device (e.g. a cable modem) to a CATV head-end (e.g. a cable operator"s central monitoring station) at any time the network device deems necessary. In normal operation, the upstream transmission power level of system 12 of Figure 1 is within defined thresholds and no alert message is generated. In normal operation, an RF carrier is modulated with MPEG2 transport protocol data using 64 or 256 QAM (Quadrature Amplitude Modulation). The MPEG2 transport data includes Ethernet formatted data which in turn includes IP data representing a User requested HTML (HyperText Mark-Up Language) web page, for example. The MPEG transport data is provided by diplexer 20 to tuner 15. Tuner 15 down-converts the input signal from diplexer 20 to a lower frequency band which is filtered by saw filter 25 to enhance signal isolation from neighboring RF channels. The filtered signal from unit 25 is level shifted and buffered by differential amplifier 30 to provide a signal compatible with MCNS interface processor 35. The resultant down converted, level-shifted signal from amplifier 30 is demodulated by MCNS processor 35. This demodulated data is further trellis decoded, mapped into byte aligned data segments, deinterleaved and Reed-Solomon error corrected within processor 35.; Trellis decoding, deinterleaving and Reed-Solomon error correction are known functions described, for example, in the reference text Digital Communication, Lee and Messerschmidt (Kluwer Academic Press, Boston, MA, USA, 1988). Processor 35 further converts the MPEG2 format data to Ethernet data frames that are provided to controller 60. Controller 60 parses and filters the Ethernet compatible data from unit 35 using filters configured from the CATV head-end. The filters implemented by controller 60 match data identifiers in incoming Ethernet frame packets provided by unit 35 with identifier values pre-loaded from the CATV head-end. The identifier values are pre-loaded during the previously performed initialization operation. By this means controller 60 implements a data admission control function forwarding selected data to local LAN devices and discarding other selected data content. This configurable filter system may be advantageously used to filter data based on metadata items in the incoming data for a variety of purposes including based on, (a) content rating for parental or other blocking control, (b) predetermined User preferences for targeting advertisements and "push-content", (c) firewall filtering, (d) identity of source, and (e) a data search function. The filtered Ethernet compatible serial data is communicated to a PC via Ethernet interface 65, filter and isolation transformer 70 and port 72. Interface 65 buffers and conditions the data from controller 60 for filtering and transforming by unit 70 for output to a PC via port 72. In similar fashion, controller 60 converts and filters data (conveyed in Ethernet MAC frames) from processor 35 for output in USB format via port 82 or in HPNA format via port 77. The USB data is buffered by transceiver 75 and filtered by noise and interference suppression (EMI/ESD) filter 80 prior to output to USB compatible LAN devices connected to port 82. Similarly, the HPNA data is conditioned by interface 62 and buffered by transceiver amplifier 67 prior to output to HPNA compatible LAN devices connected to port 77. Modem system 12 communicates data upstream from an attached PC, for example, to a CATV head-end using a transmission power level selected during the initialization routine. For this purpose, controller 60 of system 12 receives Ethernet compatible data from the attached PC via port 72, interface 65 and filter/isolation transformer 70 and provides it to processor 35. Processor 35 modulates an RF carrier with the received Ethernet format data using 16 QAM or QPSK (Quadrature Phase Shift Keying Modulation). The resultant modulated data is time division multiplexed onto cable line 10 for upstream communication via amplifier 85, transformer 87 and diplexer 20. Amplifier 85 outputs the data to the CATV head-end with an appropriate power level selected in the previously described initialization process. Transformer 87 provides a degree of fault and noise isolation in the event of a failure in the modem 12 or upon the occurrence of locally generated noise in the modem or in attached devices. In similar fashion, modem system 12 also communicates data upstream from devices attached via USB port 82 or via HPNA port 77. In an exemplary implementation, controller 60 of system 12 receives Ethernet compatible data from transceiver 75 and provides it to processor 35 for upstream communication in the manner previously described. For this purpose, transceiver 75 receives Ethernet data encapsulated within USB frames from port 82 via filter 80 and removes the USB frame data to provide Ethernet format data to controller 60. Similarly, interface 62 receives data encapsulated in HPNA format from port 77 via transceiver 67 and provides Ethernet format data to controller 60. Controller 60 is also responsive to on/off and reset switch 90 and performs a variety of functions in addition to those already described. Controller 60 configures modem 12 parameters using configuration information provided from a CATV head-end. Controller 60 also directs system 12 in synchronizing and multiplexing upstream communication onto cable line 10 and implements a rate limit in controlling upstream data traffic. Further, controller 60 bi-directionally filters received data and provides selected data to either the CATV head-end or LAN devices attached to ports 72, 77 and 82. Controller 60 also supports data ranging communication with the CATV head-end. The ranging communication is initiated by the CATV head-end and comprises the continuous but intermittent polling of individual modems to determine status and to identify modem or line failures. The architecture of the system of Figure 1 is not exclusive. Other architectures may be derived in accordance with the principles of the invention to accomplish the same objectives. Further, the functions of the elements of the cable modem system 12 and the process steps of Figure 3 may be implemented in whole or in part within the programmed instructions of controller 60. In addition, the principles of the invention may be applied in monitoring and threshold comparison of any communication parameters subject to iterative adjustment in an Internet compatible bi-directional communication system not just upstream transmission power level. The principles also apply in launching warning messages related to such parameters. WE CLAIM 1. A method for providing warning of impaired communication is a device for is bi-directionally communicating with a remote site, the mean comprising the steps of: retrieving a communication parameter value from a memory; comparing said retrieved parameter with a predetermined threshold to identify an excessive communication parameter value indicative of a potential communication link impairment; and initiating substantially periodic transmission of a message to said remote site indicating a system adjustment is necessary, in response to said comparison. 2. A method as claimed in claim 1, wherein said message comprises said parameter value. 3. A method as claimed in claim 1, wherein said parameter represents transmission upstream power level for communicating from said device to said remote site. 4. A method as claimed in claim 1, wherein said device is a cable modem and said transmission uses simple network management (SNMP) and comprising the step of comparing said retrieved parameter with minimum and maximum predetermined threshold values. 5. A method as claimed In claim 1, comprising the step of receiving said predetermined threshold value from said remote site. 6. A method as claimed in claim 5, comprising the step or using a aeraunt predetermined threshold value prior to said receiving of said predetermined threshold value from said remote site. 7. A method as claimed in claim 5, comprising the step of configuring said device with said received predetermined threshold during an initialization operation. 8. A method as claimed in claim 1, wherein said step of initiating substantially periodic transmission of said message comprises initiating transmission on one of, (a) a schedule, and (b) a repetition frequency, received from said remote site. 9. A method as claimed in claim 1, comprising the step of using one of a default schedule and repetition frequency values prior to receiving said schedule and repetition frequency values from said remote site. 10. A method as claimed in claim 1, comprising the step of terminating transmission of said message upon said comparison step indicating said retrieved parameter no longer exceeds said predetermined threshold. 11. A method as claimed in claim 1, comprising the step of displaying at least one of, (a) said parameter, (b) said predetermined threshold and (c) repetition frequency of said periodic transmission, in response to User command. 12. A method as claimed in claim 11, comprising fhe step of generation a web page for said displaying of said at least one of, (a) said parameter, (b) said predetermined threshold and (c) repetition frequency of said periodic transmission. 13. A method for providing warning of impaired communication, in a modem device for bi-directionally communicating with a remote site, the method comprising the steps of: retrieving a transmission power level value from a memory; comparing said retrieved transmission power level value with a predetermined threshold to identify an excessive transmission power level value indicative of a potential communication link impairment; and initiating substantially periodic transmission of a message having including said transmission power level to said remote site indicating a system adjustment is necessary, in response to said comprison. 14. A method as claimed in claim 13, comprising the step of terminating transmission of said message upon said comparison step indicating said transmission power level value no longer exceeds said predetermined threshold. This invention relates to a method for providing warning of impaired communication in a device for bi-directionally communicating with a remote site, the method comprising: retrieving a communication parameter value from a memory; comparing said retrieved parameter with a predetermined threshold to identify an excessive communication parameter value indicative of a potential communication link impairment; and initiating substantially periodic transmission of a message to said remote site indicating a system adjustment is necessary, in response to said comparison.

Full Text

Communication Parameter Adjustment System in an Internet-Compatible
Bi directional Communication System
Field of the Invention
This invention concerns a system for use in interactive bi-directional
communication in a device such as a cable modem, computer, TV, VCR, or an
associated peripheral device.
Home entertainment systems that combine Personal Computer and
television functions (PC/TV functions) are increasingly becoming generic, User
interactive, multiple source and multiple destination communication devices. Such
systems are required to communicate in different data formats between multiple
locations for a variety of applications in response to User requests. For example, a
system may receive data from satellite or terrestrial sources comprising High
Definition Television (HDTV) broadcasts, Multi-point Microwave Distribution
System (MMDS) broadcasts and Digital Video Broadcasts (DVB). A system may also
receive and transmit data via telephone (e.g. the Internet) and coaxial lines (e.g. cable
TV lines via a cable modem) and from both remote and local sources such as Digital
Video Disk (DVD), CDROM, VHS and Digital VHS (DVHS™) type players, PCs,
and many other types of sources.
It is desirable for Internet compatible bi-directional communication
systems that are used in conjunction with home entertainment systems to
accommodate the network cable length and associated transmission power level
variation occurring in a cable distribution network. This requirement and associated
problems are addressed by a system according to the present invention.
A system adaptively varies upstream transmission power level to
prevent communication interruption in a cable modem network. A method for
i adaptively adjusting communication operation by varying a transmission parameter
involves retrieving a communication parameter from memory and comparing the
retrieved parameter with a predetermined threshold. A message is transmitted to a
CATV head-end at a remote site representing that the parameter value indicates
adjustment of the parameter is necessary.
Brief Description of the/Drawings
In the drawing:
Figure 1 shows a block diagram of a cable modem incorporating
adaptive upstream transmission power level adjustment, according to the invention.
Figure 2 shows a cable modem start up sequence, according to the
invention.
Figure 3 presents a flowchart of a method for adaptively adjusting
i upstream transmission power level, according to the invention.
Figure 1 shows a block diagram of a cable modem (e.g. DOCSIS
standard compliant modem) capable of adaptively varying transmission power level of
signals transmitted by the modem to the CATV head-end. The cable modem provides
a communication bridge between a cable TV system and a PC (or another device such
as a TV), for example. The modem communicates with the cable system head end via
SNMP (Simple Network Management Protocol). The disclosed power level
adjustment system reduces cable modem service interruption for subscribers. This is
accomplished by providing the cable operator with an "early warning" that the
transmission power level is operating too close to a performance threshold and that, as
a result, a service interruption may occur soon.
The particular threshold concerned is a settled upstream transmit power
level from the modem to the CATV head-end. Cable operator upstream path problems
are a common cause of service interruption to subscribers due to improper upstream
path gain or loss between particular cable modems in the cable network and the cable
operator head-end. This problem may be caused, for example, by technician mis-
adjustment of cable plant amplifiers and RF splitting or combining networks. The
described cable modem system advantageously automatically senses and reports
problems to a central cable operator network management station. Thereby the
disclosed system operates with fewer subscriber service interruptions, improves
system up-time, and forestalls out-of-service conditions by detecting and correcting
such conditions before they result in subscriber service interruption.
The exemplary embodiment of Figure 1 supports cable modem
communication and decoding of data in hierarchically arranged protocols including
TCP/IP (Transmission Control Protocol/Internet Protocol), Ethernet and MPEG
(Motion Picture Experts Group) protocols (e.g. per MPEG2 ISO/TEC 13818-1 of 10th
June 1994, and ISO/IEC 13818-2, of 20th January 1995). In addition, the system of
Figure 1 is compatible with the Multimedia Cable Networks Systems (MCNS)
preliminary requirements and DOCSIS 1.0 (Data Over Cable Service Interface
Specification 1.0) requirements ratified by the International Telecommunications
Union (ITU) March 1998 and associated EuroDOCSIS requirements and other
documents provided by the IETF (Internet Engineering Task Force) RFCs (Requests
For Comment) such as RFC 2669. The RFC documents are available via the Internet
and are prepared by Internet standards working groups.
The principles of the invention may be applied to any bi-directional
communication system and are not restricted to cable, ADSL, ISDN, conventional
type modems or DOCSIS compatible modems. Further, the disclosed system
processes Internet Protocol (IP) data from a variety of Internet sources including
streamed video or audio data, telephone messages, computer programs, Emails or
other packetized data and communications, for example.
The cable modem (system 12) of Figure 1 communicates with a CATV
head-end over a bi-directional broadband high speed RF link on line 10 which
typically consists of coaxial cable or hybrid fiber/coax (HFC). The modem system 12
bi-directionally communicates with devices located at a User site over local area
networks (LANs). Typical User-side local area networks include Digital/Intel/Xerox
Ethernet compatible networks attached via connector 72. Other User-side devices
communicate via a Universal Serial Bus (USB) or HPNA (Home Phone Line Network
Association) compatible networks attached via connectors 82 and 77 respectively.
User devices attached on the Ethernet, HPNA and USB networks may include
equipment such as personal computers (PCs), network printers, video receivers, audio
receivers, VCRs, DVDs, scanners, copiers, telephones, fax machines and home
appliances, for example.
In operation, diplexer 20 of cable modem system 12 of Figure 1
separates upstream communications (sent from modem 12 to a CATV head-end) from
downstream communications (sent from a CATV head-end to modem 12) conveyed
via cable line 10. Diplexer 20 separates upstream data from downstream data based on the different frequency ranges that the upstream data (typically 5-42 MHz) and
downstream data (typically 88 - 860 MHz) respectively employ. Controller 60
configures the elements of cable modem 12 of Figure 1 to receive DOCSIS/MPEG2
transport data from the CATV head-end on cable line 10 and to convert the data to
Ethernet, USB or HPNA compatible format for output via ports 72, 82 and 77
respectively. Similarly, controller 60 configures the elements of cable modem 12 of
Figure 1 to receive Ethernet, USB or HPNA compatible data from ports 72, 82 and 77
and to convert and transmit DOCSIS transport protocol data to the CATV head-end
on cable line 10. Controller 60 configures the elements of system 12 through the
setting of control register values within these elements using a bi-directional data and
control signal bus. Specifically, controller 60 configures tuner 15, saw filter 25,
differential amplifier 30 and MCNS (Multimedia Cable Networks Systems) interface
device 35 to receive a DOCSIS formatted signal on a previously identified RF channel
frequency. The DOCSIS formatted signal comprises an MPEG2 transport protocol
format conveying Ethernet compatible data frames including IP data content.
Controller 60 employs the process shown in Figure 2 for initializing
system 12 of Figure 1 and for selecting an initial power transmission level for
transmitting of signals from system 12 to the CATV head end. Specifically, Figure 2
shows a series of operational states through which the Figure 1 DOCSIS compliant
cable modem system 12 progresses during startup to become fully operational. Upon
application of power to modem system 12 in step 250 of Figure 2, controller 60
executes bootloader software uploaded from flash memory within unit 60 to set all
modem components to their initial power on condition. In step 255 of Figure 2,
controller 60 (Figure 1) directs system 12 in determining the RF channel frequency
that tuner 15 is to be configured to receive by iteratively tuning to successive
candidate RF channel frequencies until a DOCSIS compliant signal is obtained.
Controller 60 recognizes a DOCSIS compliant signal on a candidate channel through
the successful decode by MCNS interface processor 35 of the received data and
through a correspondingly acceptable error rate for the decoded data.
In step 260 of Figure 2, controller 60 initiates Ranging by directing
system 12 in transmitting data upstream to the CATV head-end using MCNS interface
35, amplifier 85 and RF transformer 87. The Ranging function involves adaptively
and iteratively adjusting upstream and downstream communication parameters
including cable modem transmission power level and timing offset. Specifically,
system 12 incrementally increases the power level of signals conveying status
messages periodically transmitted to the CATV head end. This is done until system 12
receives an acknowledgement from the CATV head end indicating that the messages
are successfully received. The CATV head-end determines when Ranging is
completed and communicates that Ranging is terminated to system 12. At completion
of Ranging, communication between system 12 and the CATV head-end involving
Media Access Control (MAC) layer protocol is established.
In step 265 of Figure 2, controller 60 initiates Connecting by directing
system 12 in establishing bi-directional communication between modem system 12
and the CATV head-end involving DHCP (Dynamic Host Configuration Protocol)
communication with a remote DHCP server. Specifically, the system 12 IP (Internet
Protocol) address and other configuration parameters are acquired from the DHCP
server and stored in memory within unit 60. Upon successful completion of the
Connecting process, the cable modem is operable as an Internet host, and has an
assigned IP address.
In step 270 of Figure 2, controller 60 initiates Configuring by acquiring
the date and time from a remote internet TIME server using internet TIME protocol
and by downloading a Configuration File for modem system 12 from a remote TFTP
(Trivial File Transfer Protocol) server using TFTP. The configuration file includes
SNMP compatible data conveying threshold values defining warning zones near the
minimum and/or maximum operational limits for the power level to be used in
transmitting signals from system 12 to the CATV head end. System 12 sends alert
messages to the CATV head end if the transmission power level used by system 12
exceeds these threshold values and the power level lies within a warning zone. SNMP
messages may also be used to activate and deactivate the alert messages and threshold
comparison mechanism and to adjust thresholds and message repetition rate after
initialization or at other times of modem operation. The configuration file SNMP data
may also determine the repetition frequency at which alert messages (including the
actual power level value employed by system 12) are transmitted to the CATV head
end. The DOCSIS standard allows parameters such as the transmission power level
threshold values and alert message repetition frequency to be incorporated into the
mandatory configuration file that a cable modem downloads during its startup.
Thereby the threshold and repetition frequency values may be advantageously set
automatically each time a cable modem is installed and performs its DOCSIS
initialization routine. If no threshold values or alert message repetition data is
provided in the configuration file then predetermined default settings contained in
system 12 memory are used. Upon completion of the Configuring operation, modem
system 12 has received and stored sufficient information to become operational and is
in condition to receive a signal from the CATV head-end to initiate becoming fully
on-line and operational.
In step 275 of Figure 2, controller 60 initiates Registering by directing
system 12 in communicating key configuration parameters applied by the modem
system 12 to the CATV head-end for final acceptance. The CATV head-end compares
the configuration parameters employed by system 12 with the configuration
parameters previously supplied from the CATV head-end to system 12. Upon
determining that they match, the CATV head-end notifies system 12 that registration
is completed and that system 12 is on-line and operational. The process of Figure 2 is
complete at step 280.
Figure 3 shows a flowchart of a method for use by system 12 (Figure 1)
for monitoring the upstream transmitter power level of a DOCSIS-compliant cable
modem and for automatically sending a warning at predetermined intervals to a
CATV listening network management station if a settled power level falls outside a
range of acceptable values. The DOCSIS standard requires that a compliant cable
modem supports Simple Network Management Protocol (SNMP) as well as related
software procedures and virtual data stores of cable modem operating information
termed Management Information Bases (MIBs). The MIBs allow remote management
of cable modem operations by a management station, operated from the cable head-
end, or by a network operations center controlled by an Internet service provider, for
example. Further, some MIBs may be defined by a modem provider. The method of
Figure 3 is implemented in the form of a collection of settable MIB objects executed
by controller 60 (Figure 1).
In step 205 of Figure 3, following the start at step 200, if no power
threshold values or alert message repetition data is provided in the configuration file
received during initialization, controller 60 configures system 12 with default values.
The power threshold values determine alert thresholds for the power level used in
communicating signals from system 12 to the CATV head end. Also the repetition
data determines the frequency at which alert messages (including the actual power
level value employed by system 12) are transmitted to the CATV head end. The
default values may be predetermined by a modem provider and may be viewed (or
may be set in non-DOCSIS compatible applications) by User operation of an attached
PC (e.g. attached to port 72 - Figure 1) through a private MIB. In step 210, the power
threshold values or alert message repetition data, in use by system 12, may be
accessed and viewed on a web page generated by system 12 for display on an attached
PC in response to a User command via the PC. The displayed web page may be
employed as the User interface supporting User viewing of these values and also, in
non-DOCSIS compatible applications, the selection and update of these values.
In step 215, controller 60 periodically reads the current upstream
transmit power level and in step 220, compares this power level with the thresholds
previously obtained in step 205. In another embodiment, the period at which this
comparison is made may also be defined by a User via a configuration file or default
setting or by User data entry via an attached PC. If the comparison indicates that the
power level is in a warning zone, i.e. is at or above a maximum threshold, or is at or
below a minimum threshold, controller 60 initiates sending of an alert message to the

CATV head end in step 225. The thresholds may be selected, for example, so that an
alert message is generated if the settled operating cable modem upstream transmit
power is 10 dBmV or below (compared to a DOCSIS specified minimum of 8 dBmV)
or 54dBmV or above (compared to a DOCSIS specified maximum of 58 dBmV). The
alert message is automatically sent to the CATV head end as a SNMP compatible
message (termed a Trap) at a repetition frequency (e.g. every 3 minutes) defined by
the configuration repetition data obtained in step 205. The message is repeated until
cable system adjustments are made that result in clearance of the condition causing
the alert message. Once this occurs controller 60 periodically executes steps 215 and
220 and the alert message transmissions generated in step 225 cease. The frequency at
which the power level is checked in steps 215 and 220 is determined by a
configuration file parameter, or by a default value. Note, a Trap is an SNMP message
type defined in the SNMP protocol that can be launched by a networking device (e.g.
a cable modem) to a CATV head-end (e.g. a cable operator"s central monitoring
station) at any time the network device deems necessary.
In normal operation, the upstream transmission power level of system
12 of Figure 1 is within defined thresholds and no alert message is generated. In
normal operation, an RF carrier is modulated with MPEG2 transport protocol data
using 64 or 256 QAM (Quadrature Amplitude Modulation). The MPEG2 transport
data includes Ethernet formatted data which in turn includes IP data representing a
User requested HTML (HyperText Mark-Up Language) web page, for example. The
MPEG transport data is provided by diplexer 20 to tuner 15. Tuner 15 down-converts
the input signal from diplexer 20 to a lower frequency band which is filtered by saw
filter 25 to enhance signal isolation from neighboring RF channels. The filtered signal
from unit 25 is level shifted and buffered by differential amplifier 30 to provide a
signal compatible with MCNS interface processor 35. The resultant down converted, level-shifted signal from amplifier 30 is demodulated by MCNS processor 35. This
demodulated data is further trellis decoded, mapped into byte aligned data segments,
deinterleaved and Reed-Solomon error corrected within processor 35.; Trellis
decoding, deinterleaving and Reed-Solomon error correction are known functions
described, for example, in the reference text Digital Communication, Lee and
Messerschmidt (Kluwer Academic Press, Boston, MA, USA, 1988). Processor 35
further converts the MPEG2 format data to Ethernet data frames that are provided to
controller 60.
Controller 60 parses and filters the Ethernet compatible data from unit
35 using filters configured from the CATV head-end. The filters implemented by
controller 60 match data identifiers in incoming Ethernet frame packets provided by

unit 35 with identifier values pre-loaded from the CATV head-end. The identifier
values are pre-loaded during the previously performed initialization operation. By this
means controller 60 implements a data admission control function forwarding selected
data to local LAN devices and discarding other selected data content. This
configurable filter system may be advantageously used to filter data based on
metadata items in the incoming data for a variety of purposes including based on, (a)
content rating for parental or other blocking control, (b) predetermined User
preferences for targeting advertisements and "push-content", (c) firewall filtering, (d)
identity of source, and (e) a data search function. The filtered Ethernet compatible
serial data is communicated to a PC via Ethernet interface 65, filter and isolation
transformer 70 and port 72. Interface 65 buffers and conditions the data from
controller 60 for filtering and transforming by unit 70 for output to a PC via port 72.
In similar fashion, controller 60 converts and filters data (conveyed in
Ethernet MAC frames) from processor 35 for output in USB format via port 82 or in
HPNA format via port 77. The USB data is buffered by transceiver 75 and filtered by
noise and interference suppression (EMI/ESD) filter 80 prior to output to USB
compatible LAN devices connected to port 82. Similarly, the HPNA data is
conditioned by interface 62 and buffered by transceiver amplifier 67 prior to output to
HPNA compatible LAN devices connected to port 77.
Modem system 12 communicates data upstream from an attached PC,
for example, to a CATV head-end using a transmission power level selected during
the initialization routine. For this purpose, controller 60 of system 12 receives
Ethernet compatible data from the attached PC via port 72, interface 65 and
filter/isolation transformer 70 and provides it to processor 35. Processor 35 modulates
an RF carrier with the received Ethernet format data using 16 QAM or QPSK
(Quadrature Phase Shift Keying Modulation). The resultant modulated data is time
division multiplexed onto cable line 10 for upstream communication via amplifier 85,
transformer 87 and diplexer 20. Amplifier 85 outputs the data to the CATV head-end
with an appropriate power level selected in the previously described initialization
process. Transformer 87 provides a degree of fault and noise isolation in the event of a
failure in the modem 12 or upon the occurrence of locally generated noise in the
modem or in attached devices.
In similar fashion, modem system 12 also communicates data upstream
from devices attached via USB port 82 or via HPNA port 77. In an exemplary
implementation, controller 60 of system 12 receives Ethernet compatible data from
transceiver 75 and provides it to processor 35 for upstream communication in the
manner previously described. For this purpose, transceiver 75 receives Ethernet data
encapsulated within USB frames from port 82 via filter 80 and removes the USB
frame data to provide Ethernet format data to controller 60. Similarly, interface 62
receives data encapsulated in HPNA format from port 77 via transceiver 67 and
provides Ethernet format data to controller 60.
Controller 60 is also responsive to on/off and reset switch 90 and
performs a variety of functions in addition to those already described. Controller 60
configures modem 12 parameters using configuration information provided from a
CATV head-end. Controller 60 also directs system 12 in synchronizing and
multiplexing upstream communication onto cable line 10 and implements a rate limit
in controlling upstream data traffic. Further, controller 60 bi-directionally filters
received data and provides selected data to either the CATV head-end or LAN devices
attached to ports 72, 77 and 82. Controller 60 also supports data ranging
communication with the CATV head-end. The ranging communication is initiated by
the CATV head-end and comprises the continuous but intermittent polling of
individual modems to determine status and to identify modem or line failures.
The architecture of the system of Figure 1 is not exclusive. Other
architectures may be derived in accordance with the principles of the invention to
accomplish the same objectives. Further, the functions of the elements of the cable
modem system 12 and the process steps of Figure 3 may be implemented in whole or
in part within the programmed instructions of controller 60. In addition, the principles
of the invention may be applied in monitoring and threshold comparison of any
communication parameters subject to iterative adjustment in an Internet compatible
bi-directional communication system not just upstream transmission power level. The
principles also apply in launching warning messages related to such parameters.
WE CLAIM
1. A method for providing warning of impaired communication is a device for is
bi-directionally communicating with a remote site, the mean comprising
the steps of:
retrieving a communication parameter value from a memory;
comparing said retrieved parameter with a predetermined threshold to
identify an excessive communication parameter value indicative of a
potential communication link impairment; and
initiating substantially periodic transmission of a message to said remote
site indicating a system adjustment is necessary, in response to said
comparison.
2. A method as claimed in claim 1, wherein said message comprises said
parameter value.
3. A method as claimed in claim 1, wherein said parameter represents
transmission upstream power level for communicating from said device to
said remote site.
4. A method as claimed in claim 1, wherein said device is a cable modem
and said transmission uses simple network management (SNMP) and
comprising the step of
comparing said retrieved parameter with minimum and maximum
predetermined threshold values.
5. A method as claimed In claim 1, comprising the step of receiving said
predetermined threshold value from said remote site.
6. A method as claimed in claim 5, comprising the step or using a aeraunt
predetermined threshold value prior to said receiving of said
predetermined threshold value from said remote site.
7. A method as claimed in claim 5, comprising the step of configuring said
device with said received predetermined threshold during an initialization
operation.
8. A method as claimed in claim 1, wherein said step of initiating
substantially periodic transmission of said message comprises initiating
transmission on one of, (a) a schedule, and (b) a repetition frequency,
received from said remote site.
9. A method as claimed in claim 1, comprising the step of using one of a
default schedule and repetition frequency values prior to receiving said
schedule and repetition frequency values from said remote site.
10. A method as claimed in claim 1, comprising the step of terminating
transmission of said message upon said comparison step indicating said
retrieved parameter no longer exceeds said predetermined threshold.
11. A method as claimed in claim 1, comprising the step of displaying at least
one of, (a) said parameter, (b) said predetermined threshold and (c)
repetition frequency of said periodic transmission, in response to User
command.
12. A method as claimed in claim 11, comprising fhe step of generation a web
page for said displaying of said at least one of, (a) said parameter, (b)
said predetermined threshold and (c) repetition frequency of said periodic
transmission.
13. A method for providing warning of impaired communication, in a modem
device for bi-directionally communicating with a remote site, the method
comprising the steps of:
retrieving a transmission power level value from a memory;
comparing said retrieved transmission power level value with a
predetermined threshold to identify an excessive transmission power level
value indicative of a potential communication link impairment; and
initiating substantially periodic transmission of a message having including
said transmission power level to said remote site indicating a system
adjustment is necessary, in response to said comprison.
14. A method as claimed in claim 13, comprising the step of terminating
transmission of said message upon said comparison step indicating said
transmission power level value no longer exceeds said predetermined
threshold.
This invention relates to a method for providing warning of impaired
communication in a device for bi-directionally communicating with a remote site,
the method comprising: retrieving a communication parameter value from a
memory; comparing said retrieved parameter with a predetermined threshold to
identify an excessive communication parameter value indicative of a potential
communication link impairment; and initiating substantially periodic transmission
of a message to said remote site indicating a system adjustment is necessary, in
response to said comparison.

Documents:

447-CAL-2001-FORM-27.pdf

447-cal-2001-granted-abstract.pdf

447-cal-2001-granted-claims.pdf

447-cal-2001-granted-correspondence.pdf

447-cal-2001-granted-description (complete).pdf

447-cal-2001-granted-drawings.pdf

447-cal-2001-granted-form 1.pdf

447-cal-2001-granted-form 18.pdf

447-cal-2001-granted-form 2.pdf

447-cal-2001-granted-form 26.pdf

447-cal-2001-granted-form 3.pdf

447-cal-2001-granted-form 5.pdf

447-cal-2001-granted-letter patent.pdf

447-cal-2001-granted-reply to examination report.pdf

447-cal-2001-granted-specification.pdf

447-cal-2001-granted-translated copy of priority document.pdf

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Patent Number

212599

Indian Patent Application Number

447/CAL/2001

PG Journal Number

49/2007

Publication Date

07-Dec-2007

Grant Date

04-Dec-2007

Date of Filing

14-Aug-2001

Name of Patentee

THOMSON LICENSING S.A.

Applicant Address

46,QUAI A. LE GALLO, 92648, BOULOGNE CEDEX, FRANCE.

Inventors:

#	Inventor's Name	Inventor's Address
1	BROWN LARRY CECIL	20 EVENING ROSE WAY,WESTFIELD, INDIANA 46074,
2	GERVAIS JOHN ALAN	11388 ROYAL COURT, CARMEL, INDIANA 46032, USA.

PCT International Classification Number

H04L 1/24.

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	60/227,140	2000-08-22	U.S.A.