Optimum bandwidth utilization in a shared cable system data channel

• US 6,124,878 A
• Filed: 12/20/1996
• Issued: 09/26/2000
• Est. Priority Date: 12/20/1996
• Status: Expired due to Term

• Current Assignee: Time Warner Cable Enterprises LLC (Charter Communications Incorporated)
• Original Assignee: Time Warner Cable Inc. (Charter Communications Incorporated)
• Inventors: Williamson, Louis Dew, Adams, Michael Brian
• Primary Examiner(s): Faile, Andrew I.
• Assistant Examiner(s): BROWN, RUEBEN M
• Application Number:
  US08/771,034
• Time in Patent Office: 1,376 Days
• Field of Search: 348/6, 348/7, 348/10, 348/12, 348/13, 348/17, 348/384, 348/385, 348/387, 455/5.1, 455/4.2, 370/375, 370/468, 370/229-235, 370/412-418, 370/395, 395/876, 395/877, 395/200.47, 395/200.38, 364/239.1, 364/239.6
• US Class Current: 725/118
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 7/10 Adaptations for transmission by electrical cable H04N7/12 takes precedence
• CPC Class Codes: H04N 7/52 Systems for transmission of a pulse code modulated video signal with one or more other pulse code modulated signals, e.g. an audio signal or a synchronizing signal assembling of a multiplex stream by combining a video stream with other content or additional data, remultiplexing of multiplex streams, insertion of stuffing bits into the multiplex stream, assembling of a packetised elementary stream at server side H04N21/236; disassembling of a multiplex stream, remultiplexing of multiplex streams, extraction or processing of Service Information, disassembling of packetised elementary stream at client side H04N21/434

Abstract

A full service network (FSN) provides three communication channels that end between a headend and each set-top within the FSN, namely (1) forward-application-transport (FAT) channels that supply data from the headend to all or to only addressed ones of the set-tops, (2) a forward-data-channel (FDC) that supplies data from the headend to all or to only addressed set-tops, and (3) a reverse-data-channel (RDC) that supplies data from the set-tops to the headend. The FDC carries eight types of traffic, namely (1) conditional access message; (2) entitlement management messages; (3) broadcast data; (4) network management services messages or information; (5) general massaging; (6) application downloading; (7) Internet Protocol external device data services, and (8) VBR downloading. A fixed bandwidth FDC provides a first bandwidth portion for the high priority transmission of items (1), (2) and (3) at a continuous bit rate (CBR). All other items are transmitted over the FDC using at an available bit rate (ABR). A priority system for the selective transmission of these other items is based upon (1) how full a data buffer for an item is, as compared to a fullness reference, (2) how old the oldest data in the data buffer for the item is, as compared to an age reference. The fullness reference and the age reference are usually different for each of these other data items.

Claims

1. A method of maximizing bandwidth utilization of a cable TV system forward data channel that has a fixed bandwidth, said forward data channel being used to transmit the number X of high priority data messages and the number Y of lower priority data messages to a plurality of set-top terminals that are located within said cable TV system, comprising the steps of:

providing high priority transmission means for the transmission of said number X of high priority data messages over a portion of said forward data channel at a continuous bit rate;

providing the number Y of data buffers, each of said data buffers for receiving a different one of said number Y of lower priority data messages;

each of said data buffers providing a fullness output signal that is representative of a state of buffer fullness;

providing the number Y of buffer fullness reference values, one fullness reference value being provided for each different one of said number Y of data buffers;

providing the number Y of fullness comparison means, each of said fullness comparison means receiving as a first input a fullness output signal from a data buffer and receiving as a second input a corresponding buffer fullness reference value, and each of said fullness comparison means providing an output based upon a comparison of said first and second inputs;

each of said data buffers providing a data age output signal that is representative of how long data has resided in a corresponding data buffer;

providing the number Y of data age reference values, one data age reference value being provided for each different one of said number Y of lower priority data messages;

providing a plurality Y of data age comparison means, each of said data age comparison means receiving as a first input a data age output signal from a data buffer and receiving as a second input a corresponding data age reference value, and each of said data age comparison means providing an output based upon a comparison of said first and second inputs;

providing priority establishing means operating to utilize said high priority transmission means to provide for the selective transmission of said number Y of lower priority data messages at an available bit rate, wherein a priority of transmission of individual ones of said number Y of lower priority data messages is based upon said outputs of said fullness comparison means and said outputs of said data age comparison means; and

in the absence of any fullness output signal exceeding a corresponding buffer fullness reference value, and in the absence of any data age output signal exceeding a corresponding data age reference value, transmitting data contained in said number Y of data buffers in a round robin manner and at said available bit rate utilizing said high priority transmission means.

2. The method of claim 1 including the step of:

selecting said number Y of buffer fullness reference values and said number Y of data age reference values in a manner to achieved a desired priority ranging among said number Y of lower priority data items.