TW573432B - Provisioning of cable modems with transmission frequency information - Google Patents

Abstract

A system for provisioning cable modems with frequency information for communication with a cable modem termination system (CMTS) in a cable television plant. In a first embodiment, a virtual channel map of programming services (e.g., television program) is examined to determine which carrier frequencies are unused. These unused frequencies are used to form a table of available CMTS frequencies that is transmitted to the cable modems. The modems then have to only search a subset of all frequencies to locate one having a CMTS identifying signal. Alternatively, the modem can be directly informed of the CMTS frequency, so no searching is required. In a further embodiment, multiple CMTSs are used at the headend, and a traffic monitoring function dynamically adjusts the frequency used by the modems for upstream transmissions to balance the load on the CMTSs.

Description

573432

BACKGROUND OF THE INVENTION The present invention relates to cable modems used in cable television equipment to allow users to access computer networks such as the Internet, and to cable modems used at the head end of cable television equipment. The end system is "out". A cable modem is a device with which a personal computer (PC) can use a cable television network to transmit and receive data at a much faster data rate than a telephone modem. In addition to providing a faster data rate, the cable modem can keep the connection persistently without the need to establish a connection by dial-up. In addition, the cable modem can be placed outside of a video adapter (such as a terminal or integrated receiver-decoder) or a personal computer, or it can be integrated into it. Fiber modems are becoming more popular because they allow users to access the Internet at very high speeds. Either a personal computer or a TV-based device can be used. Typically, the cable modem is connected to a standard 10Base-T Ethernet card in the computer. In addition, each cable modem in each user's home or company has a coaxial cable or hybrid optical fiber coaxial cable (HFC) connected to the cable company, so as to communicate with the CMTS at the local (cable) end of the local cable company. Communicate with each other. The cable modem can receive data from the CMTS and can also send data to the CMTS. In addition, larger cable systems can use multiple CMTS to handle large amounts of cable modem traffic. _ CMTS is connected to the Internet, usually using T 1 (1.544 million bits per second) or faster. _-4- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 573432

The cable data service interface specification (D0CSIS) (and related EuroDOCSIS) has become the main standard for cable modems. With this standard, data can be transmitted downstream from the CMTS to the cable modem via Time Division Multiplexing (TDM) and video data standards (such as MPEG). The signal is transmitted in a 64 or 256 quadrature modulation (QAM) mode using a bandwidth of 42-85 million megahertz. The uplink transmission from the cable modem to the CMTS uses time-division multiple access, which is frequently seen at 5-42 MHz 'and is transmitted using orthogonal shift keying (qPSK) or i6_qam. Therefore, the cable modem must be able to determine the carrier frequency used by one or more CMTSs at the headend to transmit data downstream. Once the cable modem is properly installed (for example, at home), this judgment must be performed. Traditionally, the cable modem used a trial and error method to search all frequencies in the range of 80-86 MHz to find the CMTS (the modem will later receive data from the CMTS) ). However, this private sequence will take a considerable amount of time, up to tens of minutes; during this period, the 'cable modem' cannot be used normally by humans. Therefore, it is desired to provide a system that can quickly provide information about the carrier frequency used when transmitting the C μ T S to the cable modem to the cable modem. This system should propose a small number of frequencies for the cable modem to search for the CMTS confirmation signal. Alternatively, the system should, for example, directly use the sideband message to inform the modem of the carrier frequency used by the CMTS. This paper size applies to China National Standard (CNS) A4 (210 X 297 male)

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573432 A7 _B7 1. Description of the invention (3) ~ " " Still want to provide a system that can dynamically assign CMTS (in the head of multiple CMTS) to route the uplink modem of the cable modem to the burden Lighter CMTS to enhance the responsiveness of the system. The system should be compatible with DOCSIS and other cable modem standards. The system provided by the present invention has the above and other advantages. Summary of the invention

The present invention relates to cable modems used in cable television equipment to allow users to access computer networks (such as the Internet), and also to cable data terminal systems (CMTS). The present invention is an extension of the actual channel table / map (VCM / VCT) concept. This kind of actual channel table / map has traditionally provided information about the video and data channels planned on the cable equipment (such as channel name, frequency, channel type, and modulation mode) to the cable modem space. The actual frequency table / plan of the present invention adds a new actual channel type to indicate the type of cable modem. The operator establishes the actual channel table based on the channels of the cable modem path. This table confirms the cable data model, CMTS is the original name, and frequency. During the initialization, the cable modem code will interrogate the actual channel table, the channel type of the cable modem, or the original name specified. The frequency returned by the interrogation will be the cable modem later communicating with the CMTS. The frequency used. If the channel of the modem line is changed, the actual channel table update mechanism will be used to notify the software of the channel modem that a change has occurred and can be updated when needed. — Using the actual channel table structure, the cable The modem can respond to changes in the CMTS frequency asynchronously through the standard update mechanism.--6-This paper size applies the Chinese National Standard (CNS) A4 specification (210X 297 public love) 573432

In the first embodiment, the available cmts frequencies are listed in a table and provided to the fiber modem so that the number of carrier frequencies to be searched can be reduced. Check the actual channel list for the relevant program service to find out the unused frequencies and build this list. In a second embodiment, the cable modems are directly notified of the available frequencies for receiving CMTS data < This eliminates the need for searching. In the third embodiment, the uplink traffic of each CMTS is monitored and the uplink frequency is dynamically changed to transfer the traffic to the less burdened CMts, thereby balancing the burden of each CMTS at the headend. Presents methods and devices. Brief Description of the Drawings Figure 1 shows the headend of the present invention, which can provide a cable modem with a CMTS transmission frequency diagram, or directly explain what frequency it is. The device of the present invention shown in FIG. 2 can receive the transmission frequency information of the CMTS. Figure 3 is not the headend of the present invention, which can dynamically balance the uplink cable modem traffic load between cmts. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cable modems used in cable television equipment to allow users to access computer networks (such as the Internet), and to cable modem terminal systems (CMTS); ). Figure 1 shows the headend of the present invention. Figure 1 provides a CMTS transmission frequency diagram for the cable modem, or directly illustrates what frequency it is. The headend 100 includes an interface 110, which is used to send data to a computer network (such as the Internet 1 15) or to receive data from a computer network. For example, all paper sizes are in accordance with China National Standard (CNS) A4 (210 X 297 mm)

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573432 A7 B7 Description of the invention (5: The information received can include web pages, e-mails, etc. The information can include the request signals for requesting web pages, such as-to the addresser. 8 shown in 1 2 0 is C An example of Μ TS is π J. However, more than one CMTS can be provided. The library of modulators and demodulators 丨 thick 1 3 ϋ will use a certain carrier frequency (fd0wns "eam) will be going down from the CMTS The data transmitted to the border modem can be tuned and can also be received from the downlink cable modem * 'typically demodulated with data modulated at different carrier frequencies (fUpstream). The modulator and demodulator The library 130 includes multiple modulators / programmers to modulate program service data at various carrier frequencies. This data is provided by a processing function 140. For example, the processing may include receiving compressed bits The function of transcoding the stream, or the function of encoding the decompressed source. 'The actual channel map decoding function 150 can decode the received program service signal (this signal may be a signal of the MPEG video standard) Actual channel map data The actual channel map or channel table is a data structure that can provide information about the video and data services (channels) planned on the cable TV equipment. Main 1 by f Shicang 丨 1 giant mouth pan pigeon winter afterglow DU Table] Actual channel map ~ Channel name Carrier frequency Channel negative type_Modulation mode factory ^ HBO f 1 Satellite quadrature amplitude modulation can use η ABC f3 Satellite quadrature amplitude Φ & Drama f4 Satellite forward modulation ΦΙ »Can use f5 I- NBC f6 satellite orthogonal modulation can use f7 CNN f8 satellite orthogonal amplitude modulation ESPN f9 satellite_to intermodulation amplitude This paper size applies Chinese National Standard (CNS) A4 specification (210 X 297 mm) binding 573432 A7 B7 V. Invention Description U) The CMTS frequency function 160 includes a table forming function 162, which can use the actual channel map to make an available CMTS frequency table, or includes a frequency establishment function 164, which can directly indicate the available CMTS Frequency. For example, function 162 can form the available frequency table shown in Table 2 from the actual channel legend in Table 1. Table 2-Available frequency table

The list of available frequencies indicates the downlink carrier frequency that one or more CMTSs at the head end may use. This information will be provided to the modulation / demodulation library 130 to accept modulation of any available modulation carrier frequency, and then transmitted to one or more cable data through the wired device 170 machine. The available frequency information can also be provided to CMTS 120 from function 162 to enable the MCTS to select the frequency used to transmit its internal data (such as Internet data) to the cable modem. The cable modem searches for the received carrier frequency in the available frequency table to find the frequency used by the CMTS. The frequency of the CMTS can typically be confirmed by a pre-assigned CMTS confirmation signal, which is basically an arbitrary transmission sequence of the acknowledgement packet. This method is beneficial. This is because the number of frequencies available is generally a part of the total number of frequencies in the actual channel map, so the cable modem finds out the CMTS frequency. This paper size applies the Chinese National Standard (CNS) A4 specification. (21 × 297 mm) 573432 A7 B7 5. The speed of the invention (7) can be much faster than searching each frequency in the actual channel map and then finding the CMTS confirmation signal. Alternatively, the CMTS frequency can be specified using the function 164 code, and then transmitted to the modulation / demodulation library 130 to accept the modulation of any available modulation carrier frequency (such as the W side frequency) and pass through the modulation The wired device 170 transmits to one or more cable modems. In particular, when only one CMTS is used, this frequency data can be transmitted to all cable modems in the network. If multiple CMTS are used, the identification number of the modem (or video adapter) can be used to transmit the frequency data to the designated cable modem or modem group. This can be achieved, for example, using known video conversion addressing techniques. Function 164 may include memory to store these modem frequency assignments. The specific frequency information can be provided by the function 164 to the (:) ^ 1 ^ 120 to indicate which frequency the CMTS should use to transmit its data to the cable modem. The right is using this specific embodiment, then the The cable modem can use the frequency information it receives to immediately find the carrier frequency used by the CMTS. The advantage of this method is that the modem does not have to check every frequency in a trial and error manner to "hunt," the CMTS Acknowledgement signal. Fig. 2 is a device for receiving CMTS transmission frequency information according to the present invention. The device 200 may have various forms. For example, a single device may include a cable modem section 205 and a video / audio multiple receiver section 26 , And a personal computer (PC) section 265. Alternatively, these sections may be provided in different devices or combined in other ways. For example, the cable modem section 205 and the video / audio receiver section 260 may be combined in Together, and the individual 573432

% Shame is still separated. The output device 2 8 can be combined with other parts or separated. The example cable modem 205 includes a modulation / demodulation function 21, which is used to decode data received from a CMT s by the lower carrier frequency of the cable machine, and to alter the positive carrier frequency. Upstream to CMTS. For example, the browser 270 in the personal computer 265 can send a request signal to the modulation / demodulation function 2 10 through the interface 250. This function can modulate and transmit the request ## to the CMTS. That. "^^ The request signal is then transmitted to the Internet. In a specific embodiment, the modulation / demodulation function 21 will demodulate the available frequency table provided by function 162 in FIG. I The form will be restored (eg, decoded) and then selectively stored in function 22. Function 22 is best to use non-volatile memory so that the stored information can be turned on every time the device 200 is powered on. Then you can reply. In addition, the available frequency table or the demodulation function 2 10 (which is used for cMTS data) or the demodulation function 262 (which is used for program service data) The specific frequency is provided to the device 200. When the available channel table exists, the CMTS confirmation signal positioning function 24 can use it to find the c MT s confirmation signal by searching the carrier frequency in the table. To complete this action, The function 240 will cause the demodulator 21 to test all the carrier frequencies in the table. Once the CMTS is found and the signal is recognized, the function 24 will note the corresponding carrier frequency and store it in the memory 22. Then, The demodulator 210 will still tune to the CMTS carrier frequency carrying the confirmation signal. ____ -11- This paper size applies to China National Standard (CNS) Α4 (210 X 297 mm)

Binding

Line 573432 A7 B7 V. Description of the invention (9 The information from the CMTS is then received, such as a signal from the Internet requesting a web page. Note 'This specific embodiment allows the modem 205 to find the CMTS very quickly Carrier frequency, without testing all possible frequencies. In a specific embodiment, function 210 demodulates the specific frequency information provided by function 164 in Figure i. The specific frequency information is restored (for example, decoded) And later) and optionally stored in function 22. This particular frequency will be used by the remote demodulator 2 10, and immediately adjusted to the specified CMTS carrier frequency to accept the data from cmtS. & Gt Wang Yi 'This specific embodiment allows the modem to immediately find the CMTS carrier frequency. The price of this specific embodiment is that for a head that uses multiple CMTSs, it must explain which To which cable modem or modem group a CMTS is to be transmitted, the frequency used or the modem associated with it may change. In addition, it is necessary to Model or group identification number to find the modem or cluster of modems to which the specific frequency information is to be transmitted. If there is no new frequency meter or specific frequency is transmitted from the headend, the demodulator 210 can , Automatically retune to the confirmed CMTS carrier frequency. If a new CMTS carrier frequency table is transmitted from the head end, the CMTS confirmation signal will be confirmed again to see if the relevant carrier frequency has changed. Or, adjust Go to this new specific frequency. The video / audio receiver 26 shown in the figure is used simultaneously with the cable modem 205. However, this is not necessary. In some cases, it comes from the Internet Or other network data can be received through the cable modem

573432 A7 ___B7 V. Description of the invention (10) It is displayed on the output device 28 with the program service (for example, a TV program). In other cases, the user only uses the cable modem and does not receive such program services. The video / audio receiver 26 receives program services from the head end and demodulates them at a demodulator 264. Then, the data is decoded and other necessary programs are executed to provide a signal to the output device 280 (such as a TV). Note that the browser 270 shown also provides a signal to the output device 28. Alternatively, or in addition, the browser 270 may have its own dedicated output, such as a personal computer monitor. However, the arrangement shown is suitable for integrating TV and Internet systems. The headend of the present invention shown in FIG. 3 can dynamically balance the traffic burden of the uplink cable modem among multiple CMTSs. Elements with the same number are the same in each drawing. Larger cable TV networks usually use multiple CMTS (such as n CMTS 120 '..., 122 in the example have Internet interfaces 1 1 0,., 1 1 2)' to handle a larger number of cables Modems and Internet traffic. For example, 'Each CMTS can establish its own connection to the Internet via the τ 1 line, for example. Here, the traffic monitor 31 monitors the amount of uplink cable modem data received by each CMTS 120, ..., 122. For example, a method that can be used as a traffic monitor 3 1 0 to monitor the amount of received data is, for example, using a bit counter or some other method of measuring traffic, such as measuring the reception of a certain CMTS. The number of messages received measures the amount or amount of time that a certain CMTS is busy receiving uplink messages, and so on. ---------- -13- _ This paper size applies to China National Standard (CNS) A4 specifications (210X297 tolerance :) 573432 A7

To balance the burden of each CMTS, the traffic monitor 31 instructs Cmts to start receiving uplink cable modem data at different frequencies (i.e., different demodulator from the library " 0). The traffic monitor can also communicate with the available / specific frequency function 320, so that the cable modems use different uplink frequencies. This can be used, for example, to directly allocate the required frequencies to the modems. Way to %%. Note that the destination of the uplink data sent by the cable modem, C M T S, and the source of the downlink data it receives, CMTS, may be different. The available / specific frequency function 320 may incorporate the functions of the FIG. 1 * CMTS frequency function 160, for example, to inform the CMTS 120, ..., 122 of the available or assigned downlink frequencies. Therefore, the headend 300 selectively informs such cable modems to change the carrier frequency when it transmits uplink data (such as transmitting DOCSIS data), so that the cable equipment can dynamically select the uplink traffic. Go to these relatively lightly burdened CMTS to improve the responsiveness of the system. Thus, it can be seen that the present invention provides a system that enables a cable modem to efficiently find the downstream frequency to restore the data from the CMTS. These cable modems can be equipped with a CMTS frequency meter that can be used to reduce the number of carrier frequencies that must be searched when locating the CMTS confirmation signal, or directly inform the modems of specific frequencies to avoid searching. In addition, monitoring the upstream traffic of each CMTS and dynamically changing the upstream frequency monitored by each CMTS accordingly, transferring the traffic to a lighter CMTS 'can balance the burden of multiple cmts in the headend. Although the present invention has been described in various specific embodiments, it should be ___ 14- This paper size is applicable to China National Standard (CNS) 8-4 specification (21〇x 297 mm)

Claims (1)

573432 VI. Patent Application No. 090119784 g Chinese Application for Patent Scope Replacement (December 1992 p Application for Patent Scope 1. A method used at the head end of a cable television network, which can provide frequency information to at least one of the network The cable modem to allow communication with the headend 'includes the steps of: receiving, at the headend, channel map information indicating a carrier frequency that has been used to deliver program services and is unavailable, and at least one that has not yet been used Available carrier frequency for transmitting program services; providing a signal from the headend to the at least one cable modem to inform the cable modem of the at least one available carrier frequency; and the headend It plans at least one cable modem terminal system that uses the at least one available carrier frequency to provide data to the at least one cable modem. 2 · The method according to item 丨 of the scope of patent application, wherein: At least one cable modem terminal system is planned to transmit a confirmation letter on the at least one available carrier frequency For the detection of the at least one cable modem. 3 _ As for the method in the scope of the patent application, the far k number clearly states that the at least one cable modem is using the at least one Carrier frequency for receiving data from the at least one cable modem terminal system. 4 · The method of claim 1 in the patent application range, wherein: the signal clearly indicates' the at least one cable modem is Use the at least one available carrier frequency to provide data to the at least one cable modem terminal system. This paper size applies to the Chinese National Standard (CNS) A4 specification (21〇χ 297 mm) • If the method of applying for the patent I is the first, the frequency received at the headend is used to transmit the program M1. , Tu Beixun, pointed out that a number of unused carrier-class carrier rates are available; and cable modems. The carrier frequency is used to inform the at least one of the "· method as claimed in the scope of patent application No. 5 wherein: 7's borderline modem is suitable for searching for the number of carrier frequencies provided to it to find the carrier frequency ' At least one cable modem is a specific frequency used by it to provide data to the at least one cable modem. 'Such as the method of applying for the scope of patent No.6, in which: far-distance-a fiber-line modem by detecting the slow-line modem located there • The terminal system confirms the signal carrier to find the specific frequency. . ♦ A head-end device for a private cable television network, which can provide frequency information to at least one of its cable modems in the network to allow communication with the head-end, including: receiving channel map information at the head-end Device, the channel map information indicates a carrier frequency that has been used for transmitting program services and is not available, and at least one available carrier frequency that has not been used for transmitting program services; providing a signal from the headend to the at least one A cable modem to inform the cable modem of at least one device capable of using carrier frequency; and -2-this paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) 573432 Scope of patent application At least one cable modem terminal system is planned at the head end, and the at least one available carrier frequency is used to provide data to the at least one cable modem. 9. A method for enabling at least one cable modem to provide itself with frequency information in a cable television network to allow communication with the head-end of the network, comprising the steps of: receiving from the head-end A signal that confirms a plurality of available carrier frequencies that are not yet used in the transmission service; and searches for the plurality of available carrier frequencies provided to it to find at least one cable data at the headend Machine terminal systems are used to provide information to the specific frequencies of these cable modems. 10. The method according to item 9 of the scope of patent application, wherein: the available carrier frequencies are obtained from the channel map information received by the headend, and the channel map information contains the service that has been used to transmit the program service and cannot be used. Carrier frequency, and the available carrier frequency. U. The method according to item 9 of the scope of patent application, wherein: the cable modem is adapted to use the specific frequency to provide a terminal modem system. 12. The method according to item 9 of the patent application scope, wherein: the cable modem finds the specific frequency by detecting the confirmation k number of the cable modem terminal system. 13. —A cable modem device that can provide itself with low frequency information in a cable TV network to allow communication with the head-end of the network, which includes, -3- National National Standard (CNS) A4 specifications (210X297 public funds) A device that receives a signal from a head-end, the signal confirming a plurality of available carrier frequencies that are not yet used for transmitting program services; and searching for the plurality of available carrier frequencies provided to it to find the head-end At least one cable modem end system is a device used to provide information to the specific frequencies of the cable modems. 14. A method for enabling at least one of the modems to provide themselves with frequency information in an electrically-wound television network to allow communication with the head-end of the network. The method includes the following steps: A signal at the headend that indicates at least one available carrier frequency to receive data from at least one cable modem terminal system at the headend; wherein: the at least one available carrier frequency has not been used for transmission The show month service. 15. The method according to item 14 of the scope of patent application, wherein: the at least one available carrier frequency is obtained from channel map information received by the headend, and the channel map information includes services used for transmitting program services. A carrier frequency that is not available for use, and the at least one carrier frequency that is available for use. 16 · —A cable modem device that can provide itself with frequency information in a cable television network to allow communication with the head end of the network, which includes: a device that receives a signal from the head end, the signal indicating at least A carrier frequency can be used to receive data from at least one cable modem terminal system at the head end; of which: -4- this paper size ㈣ τ Seizuka standard _ M specifications _ χ tear public love) 573432 6 2. The scope of the patent application The at least one available carrier frequency has not been used for transmitting program services. 17 · —A method for receiving uplink data from multiple cable modems in a cable television network at the head end, which includes the following steps: A plurality of receivers are provided at the head end for receiving The cable modem terminal system of the uplink data, wherein each cable modem terminal system is assigned to at least one relevant uplink carrier frequency to receive a portion of the uplink data; monitoring each cable modem terminal system received The amount of uplink data; and respond to the monitoring steps to balance the burden of the uplink data of each cable modem terminal system. 18. The method according to item 17 of the scope of patent application, wherein: and the balancing step includes the step of dynamically changing the at least one uplink carrier frequency allocated to the at least one cable modem terminal system. 19. The method of claim 17 in the scope of patent application, wherein: The balancing step includes the steps of transmitting data to at least one of the radio modems, causing it to use a different uplink carrier frequency. 2〇 · -The head-end device of the video network, which receives uplink data from multiple cable modems in the network, including multiple cable modem terminals for receiving the uplink data System, which ::-The cable modem terminal system allocates to at least one relevant uplink carrier frequency for receiving a part of the uplink data; the standard is applicable _ Jia Jin Zhuan (CNS) A4 specifications (Public reply -5- 573432 8 8 8 8 A BCD VI. Patent application device for monitoring the amount of uplink data received by each cable modem terminal system; and responding to the monitoring device, the uplink of each cable modem terminal system Device for balancing data load. -6- This paper size applies to China National Standard (CNS) A4 (210 x 297 mm).