Providing constant bit rate upstream data transport in a two way cable system by scheduling preemptive grants for upstream data slots using selected fields of a plurality of grant fields

• US 5,966,163 A
• Filed: 10/16/1996
• Issued: 10/12/1999
• Est. Priority Date: 10/20/1995
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Koperda, Francis R., Lin, Bouchung
• Primary Examiner(s): Barry, Lance Leonard
• Application Number:
  US08/732,668
• Time in Patent Office: 1,091 Days
• Field of Search: 348/12, 455/5.1, 370/430, 370/439, 370/440, 370/442, 393/200.93
• US Class Current: 725/117
• CPC Class Codes: H04J 3/1694 Allocation of channels in TDM/TDMA networks, e.g. distributed multiplexers Passive Optical Networks H04Q11/0062
• CPC Class Codes: H04J 3/247 ATM or packet multiplexing
• CPC Class Codes: H04L 2012/561 Star, e.g. cross-connect, concentrator, subscriber group equipment, remote electronics
• CPC Class Codes: H04L 2012/5616 Terminal equipment, e.g. codecs, synch.
• CPC Class Codes: H04L 2012/563 Signalling, e.g. protocols, reference model
• CPC Class Codes: H04L 2012/5632 Bandwidth allocation
• CPC Class Codes: H04L 2012/5675 Timeslot assignment, e.g. TDMA
• CPC Class Codes: H04L 2012/5679 Arbitration or scheduling
• CPC Class Codes: H04N 21/2385 Channel allocation H04N21/266 takes precedence; Bandwidth allocation H04N21/24 takes precedence ; allocation of channels according to the instantaneous demands of the users in time-division multiplex systems H04J3/1682; admission control, resource allocation in open networks H04L12/5692; arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896; negotiating bandwidth in wireless networks H04W28/16
• CPC Class Codes: H04N 21/2393 involving handling client requests scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04N 21/2402 Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• CPC Class Codes: H04N 21/6583 Acknowledgement
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

In a two way cable system that includes a controller and a plurality of user terminals, a method of granting rights for upstream data transmission from the user terminals includes processing contention requests to generate contention grants and maintaining a list of connections, each connection having specified therefor a predetermined bit rate. The controller sends a downstream data stream to the user terminals and receives an upstream data stream from the user terminals. The downstream data stream includes a plurality of grant fields, and the upstream data stream includes upstream data slots and upstream control slots. The method further includes scheduling preemptive grants for upstream data slots using selected fields of the plurality of grant fields so as to provide preemptive grants for upstream data transport at a bit rate specified for each connection, sending to the user terminals a data transmission grant in a grant field of the plurality of grant fields for which a preemptive grant is scheduled, and sending to the user terminals a data transmission grant in a grant field of the plurality of grant fields in which a contention grant is pending and no preemptive grant is scheduled.

Claims

1. In a two way communication system that includes a controller and a plurality of user terminals, the controller sending a downstream data stream to the user terminals and receiving an upstream data stream from the user terminals, the downstream data stream including a plurality of grant fields, the upstream data stream including upstream data slots and upstream control slots, a method of granting rights for upstream data transmission from the user terminals, the method comprising steps of:

processing contention requests to generate contention grants;

maintaining a list of connections, each connection having specified therefor a predetermined bit rate;

scheduling preemptive grants for upstream data slots using selected fields of the plurality of grant fields so as to provide preemptive grants for upstream data transport at a bit rate specified for each connection;

sending to the user terminals a data transmission grant in a grant field of the plurality of grant fields for which a preemptive grant is scheduled; and

sending to the user terminals a data transmission grant in a grant field of the plurality of grant fields in which a contention grant is pending and no preemptive grant is scheduled.

2. The method of claim 1, wherein:

preemptive grants are scheduled to grant transport rights for one of constant bit rate data and variable bit rate data; and

contention grants are generated to grant data transport rights for available bit rate data.

3. The method of claim 1, wherein the step of maintaining includes:

initializing the list of connections when the list contains no connections and a connection is requested; and

deleting a connection when the list contains at least a first connection and deletion of the first connection is requested.

4. A controller in a two way cable system that includes a plurality of user terminals, the controller being capable of sending a downstream data stream to the user terminals and receiving an upstream data stream from the user terminals, the downstream data stream including a plurality of grant fields, the upstream data stream including upstream data slots and upstream control slots, the controller for granting rights for upstream data transmission from the user terminals, the controller comprising:

means for processing contention requests to generate contention grants;

means for maintaining a list of connections, each connection having specified therefor a predetermined bit rate;

means for scheduling preemptive grants for upstream data slots using selected fields of the plurality of grant fields so as to provide preemptive grants for upstream data transport at a bit rate specified for each connection;

means for sending to the user terminals a data transmission grant in a grant field of the plurality of grant fields for which a preemptive grant is scheduled; and

means for sending to the user terminals a data transmission grant in a grant field of the plurality of grant fields in which a contention grant is pending and no preemptive grant is scheduled.

5. The controller of claim 4, wherein:

preemptive grants are scheduled to grant transport rights for one of constant bit rate data and variable bit rate data; and

contention grants are generated to grant data transport rights for available bit rate data.

6. The controller of claim 4, wherein the means for maintaining includes:

means for initializing the list of connections when the list contains no connections and a connection is requested; and

means for deleting a connection when the list contains at least a first connection and deletion of the first connection is requested.