Prioritized virtual connection transmissions in a packet to ATM cell cable network

• US 6,028,860 A
• Filed: 10/23/1996
• Issued: 02/22/2000
• Est. Priority Date: 10/23/1996
• Status: Expired due to Term

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: Com21, Inc.
• Inventors: Raissinia, Alireza, Helton, Sanford L., Thaker, Malay M., Gordon, Paul A., Laubach, Mark E., Sabin, Michael J., Nichols, Kathleen M.
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): NGUYEN, STEVEN H D
• Application Number:
  US08/731,958
• Time in Patent Office: 1,217 Days
• Field of Search: 370/395, 370/474, 370/475, 370/476, 370/478, 370/432, 370/442, 370/443, 370/444, 370/458, 370/461, 370/462, 348/6, 348/7, 348/10, 348/11, 348/12, 348/13, 348/14, 348/16, 348/17, 395/200.55, 395/200.37, 455/5.1, 709/207, 709/225
• US Class Current: 370/395.64
• CPC Class Codes: H04L 2012/561 Star, e.g. cross-connect, concentrator, subscriber group equipment, remote electronics
• CPC Class Codes: H04L 2012/5638 Services, e.g. multimedia, GOS, QOS
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

Bi-directional communications system in a CATV network utilizing cell-based Asynchronous Transfer Mode (ATM) transmissions. Packet data existing in any one of several different formats are first converted into ATM cells by a headend controller. Individual cells are then assigned a virtual connection by the headend controller. Based on the virtual connection, the cells can be prioritized and routed to their intended destinations. The cells are transmitted in a shared radio frequency spectrum over a standard cable TV network. A subscriber terminal unit demodulates the received RF signal and processes the cells for use in a computer. Likewise, computers may transmit packet data to their respective subscriber terminal units which are sent to the headend controller over the same CATV network. Hence, the present invention offers a flexible, effective, economic, and fully integrated multimedia bearer system granting immediate support for Internet services, traditional voice telephony, and digital video services over a CATV network.

Claims

1. A cable network comprising:

one or more cables for conveying radio frequency signals;

a plurality of cable modems coupled to the plurality of cables, wherein the cable modems accept data packets, convert the packet data into asynchronous transfer mode cells which are transmitted by radio frequency over the cables;

a headend controller coupled to the cables for accepting the radio frequency signals transmitted by the plurality of cable modems and wherein the headend controller sends one or more radio frequency signals containing asynchronous transfer mode cells over the cables to the plurality of cable modems according to virtual connection information assigned to individual cells;

a network interface coupled to the headend controller for inputting packet data to the headend controller and receiving packet data from the headend controller;

a converter coupled to the headend controller which converts packet data from the network interface into asynchronous transfer mode cells for transmission by the headend controller to the plurality of cable modems and also converts asynchronous transfer mode cells generated by the cable modems and received by the headend controller into packet data for output by the network interface, wherein the asynchronous transfer mode cells contain video, audio or textual information such that cells are prioritized in order for transmission according to each individual cell'"'"'s delay sensitivity;

a shared media which is used to establish a downstream channel from the headend controller to the plurality of cable modems and to establish a plurality of upstream channels from the plurality of cable modems to the headend controller;

a contention resolution circuit within the headend controller for resolving contentions which may arise according to a directed exponential backoff scheme with implicit feedback.

2. The cable network of claim 1 further comprising encryption circuitry for encrypting ATM cell payloads.

3. A cable network comprising:

one or more cables for conveying radio frequency signals;

a plurality of cable modems coupled to the plurality of cables, wherein the cable modems accept data packets, convert the packet data into asynchronous transfer mode cells which are transmitted by radio frequency over the cables;

a headend controller coupled to the cables for accepting the radio frequency signals transmitted by the plurality of cable modems, wherein the headend controller sends one or more radio frequency signals containing asynchronous transfer mode cells over the cables to the plurality of cable modems according to virtual connection information assigned to individual cells and wherein the headend controller further comprises a null-grant circuit for minimizing contention, wherein a null-grant signal is transmitted to acknowledge and remove a requesting cable modem from contention for a pre-determined amount of time;

a network interface coupled to the headend controller for inputting packet data to the headend controller and receiving packet data from the headend controller;

a converter coupled to the headend controller which converts packet data from the network interface into asynchronous transfer mode cells for transmission by the headend controller to the plurality of cable modems and also converts asynchronous transfer mode cells generated by the cable modems and received by the headend controller into packet data for output by the network interface, wherein the asynchronous transfer mode cells contain video, audio or textual information such that cells are prioritized in order for transmission according to each individual cell'"'"'s delay sensitivity;

a shared media which is used to establish a downstream channel from the headend controller to the plurality of cable modems and to establish a plurality of upstream channels from the plurality of cable modems to the headend controller.

4. The cable network of claim 3, wherein the headend controller identifies a virtual path for routing an asynchronous transfer mode cell to a specific set of cable modem(s).

5. The cable network of claim 3, wherein the packet data correspond to Ethernet format.

6. The cable network of claim 3, wherein there are a plurality of upstream channels and a plurality of downstream channels between the headend controller and the cable modems.

7. A cable modem for transmitting and receiving RF signals over a cable network, comprising:

a computer interface for handling packet data between the cable modem and a computer;

a processor coupled to the computer interface for converting the packet data into ATM cells and for converting ATM cells to data packets;

an RF transmitter coupled to the processor for generating RF signals conveying ATM cell information to a headend controller, wherein the computer generates packet data which are converted into ATM cells and transmitted over the cable network as RF to the headend controller and wherein the ATM cell information contains video, audio, or textual information and individual cells are prioritized according to their respective sensitivity for incurred delays;

an RF receiver coupled to the processor for receiving RF signals having ATM cell information from the headend controller, wherein the headend controller broadcasts RF signals over the network which are received by the cable modem according to virtual connection information assigned to individual cells, converted into packet data and output to the computer;

a shared medium is used to establish a downstream channel from the headend controller to the cable modem and to establish an upstream channel from the cable modem to the headend controller;

a contention circuit for handling contentions according to a directed exponential backoff scheme with implicit feedback.

8. The cable modem of claim 7 further comprising encryption circuitry for encrypting ATM cell payloads associated with transmissions.

9. The cable modem of claim 7 further comprising a circuit for recognizing a null-grant signal generated by the headend controller, wherein the null-grant signal minimizes contention by acknowledging that the cable modem has indicated a request to transmit and removes the cable modem for a pre-determined amount of time.

10. The cable modem of claim 7, wherein RF signals are received by the cable modem according to a virtual path identifying the cable modem as belonging to a specific set of cable modem(s).

11. The cable modem of claim 7, wherein the packet data correspond to Ethernet packets.

12. A headend controller comprising:

a headend controller for transmitting RF signals over a cable network to a plurality of subscriber units and for receiving a plurality of RF signals from the subscriber units, comprising;

a network interface for handling packet data between the headend controller and a computer network;

a processor coupled to the network interface for converting the packet data into ATM cells and for converting ATM cells to data packets;

an RF transmitter coupled to the processor for generating RF signals conveying ATM cells according to virtual connection information assigned to individual cells for routing to the plurality of subscriber units, wherein the network interface accepts packet data which are converted into ATM cells and transmitted over the cable network as RF to designated subscriber units and wherein the ATM cells contain video, audio, or textual information which are prioritized for transmission on a cell basis according to an individual cell'"'"'s sensitivity for incurred delays;

an RF receiver coupled to the processor for receiving RF signals having ATM cell information from the plurality of subscriber units, wherein the subscriber units transmit RF signals over the cable network to the headend controller which converts the RF signals into packet data for output to the computer network;

a shared medium is used to establish a downstream channel from the headend controller to the cable modems and to establish a plurality of upstream channels from the cable modems to the headend controller;

a contention circuit for handling contentions according to a directed exponential backoff scheme with implicit feedback.

13. The headend controller of claim 12 further comprising encryption circuitry for encrypting an ATM cell payload.

14. The headend controller of claim 12 further comprising a circuit for generating a null-grant signal to minimize contention by acknowledging that the cable modem has indicated a request to transmit and removing that cable modem from contention for a pre-determined amount of time.

15. The headend controller of claim 12, wherein one or more cable modems are identified according to a virtual path established by the headend controller.

16. The headend controller of claim 12, wherein the packet data correspond to Ethernet data packets.

17. A method of providing two-way communications between a headend controller and a plurality of cable modems comprising the step of:

the headend controller;

accepting ethernet data from a first device coupled to the headend controller;

converting the ethernet data into ATM data containing video, audio, or textual information which are prioritized according to their respective sensitivity toward incurred delays;

assigning virtual connection information to individual cells which is used to prioritize and route the cells to one or more of the cable modems;

transmitting the ATM data as RF over a shared medium to the plurality of cable modems;

the designated cable modem;

receiving the ATM data generated by the headend controller;

converting the ATM data into ethernet data;

supplying the ethernet data to a second device coupled to the designated cable modem;

converting ethernet data generated by the second device into ATM data for transmission as RF over the shared medium to the headend controller;

generating control information for managing transmissions by the cable modems, wherein the control information is sent in ATM cells;

establishing a downstream channel from the headend controller to the cable modems and a plurality of upstream channels from the cable modems to the headend controller;

resolving contentions according to a directed exponential backoff scheme with implicit feedback.

18. The method of claim 17 further comprising the step of encrypting ATM payload data for providing secure transmissions.

19. The method of claim 17, wherein one or more cable modems are identified according to a virtual path established by the headend controller.

20. The method of claim 17, wherein the packet data corresponds to an Ethernet packet data.

21. The method of claim 17 further comprising the step generating control information for managing transmissions by the cable modems, wherein the control information is set in ATM cells.

22. The method of claim 17, wherein the ATM data contain video, audio, or textual information which are prioritized according to their respective sensitivity toward incurred delays.

23. The method of claim 17, wherein a shared medium is used to establish a downstream channel from the headend controller to the cable modems and to establish a plurality of upstream channels from the cable modems to the headend controller.

24. A method of providing two-way communications between a headend controller and a plurality of cable modems comprising the step of:

the headend controller;

accepting ethernet data from a first device coupled to the headend controller;

converting the ethernet data into ATM data containing video, audio, or textual information which are prioritized according to their respective sensitivity toward incurred delays;

assigning virtual connection information to individual cells which is used to prioritize and route the cells to one or more of the cable modems;

transmitting the ATM data as RF over a shared medium to the plurality of cable modems;

the designated cable modem;

receiving the ATM data generated by the headend controller;

converting the ATM data into ethernet data;

supplying the ethernet data to a second device coupled to the designated cable modem;

converting ethernet data generated by the second device into ATM data for transmission as RF over the shared medium to the headend controller;

generating control information for managing transmissions by the cable modems, wherein the control information is sent in ATM cells;

establishing a downstream channel from the headend controller to the cable modems and a plurality of upstream channels from the cable modems to the headend controller;

generating a null-grant signal to minimizes contention by acknowledging that one of the cable modems has indicated a request to transmit and removing that cable modem from contention for a pre-determined amount of time.

25. A method for data communication between a headend controller coupled to a plurality of cable modems, comprising the steps of:

establishing by the headend controller, a set of one or more virtual connections between the headend controller and a set of one or more cable modems;

sending an ATM cell by the headend controller through a cable network to the plurality of cable modems;

the set of one or more cable modems receiving the ATM cell associated with a specific virtual connection;

establishing a virtual connection to distribute grant instruction from the headend controller to the set of one or more cable modems;

sending by the headend controller, grants to the cable modems, wherein the grants include direct grants, contention grants, or null grants;

sending of data upstream by the cable modems in response to the grants.

26. The method of claim 25, wherein a virtual path identifier of the ATM cell corresponds to the unique identifier associated with a specific cable modem.

27. The method of claim 25, wherein a virtual path identifier of the ATM cell corresponds to the unique identifier associated with a subset of cable modems on a downstream channel.

28. The method of claim 25, wherein a virtual path identifier of the ATM cell corresponds to the unique identifier associated with each cable modem on a downstream channel.

29. A method of, data communication between a headend controller coupled to a plurality of cable modems, comprising the steps of:

establishing by the headend controller, a set of one or more virtual connections between the headend controller and a set of one or more cable modems;

sending an ATM cell by the headend controller through a cable network to the plurality of cable modems;

the set of one or more cable modems receiving the ATM cell associated with a specific virtual connection;

establishing a virtual connection to distribute grant instruction from the headend controller to the set of one or more cable modems;

sending by the headend controller, grants to the cable modems;

sending of data upstream by the cable modems in response to the grants, wherein each cable modem sharing a slotted upstream channel and a channel access mechanism employs a repeating integer counting range and the cable modems share a same starting inter and the integer value on which to begin a repeat count.

30. The method of claim 29, wherein the headend controller issues grants to cable modems such that a mixture of constant bit rate and variable bit rate service allocations are scheduled on a same upstream channel.